Jump to content


Photo
* * * * * 1 votes

It's not Sirt1 or Sirt 2, its Sirt3!!

new research

  • Please log in to reply
49 replies to this topic

#1 PWAIN

  • Registered User
  • 1,136 posts
  • 228
  • Location:Melbourne

Posted 19 November 2010 - 05:02 AM


Looks like sirt3 is the key...

While scientists have long known that eating less prolongs life span, the UW-Madison researchers have effectively discovered how this process works.

They have identified a substance in cells known as Sirt3 which has a direct connection to the anti-aging effects seen with low calorie intake.


http://www.theaustra...y-1225956574684
  • like x 3
  • dislike x 1

#2 medievil

  • Registered User
  • 3,335 posts
  • 20
  • Location:Belguim

Posted 19 November 2010 - 05:27 AM

AT1 antagonists activate SIRT3 and the CLOCK anti aging gene.

sponsored ad

  • Advert

#3 health_nutty

  • Registered User
  • 2,380 posts
  • 86
  • Location:California

Posted 19 November 2010 - 06:59 PM

Are there any SIRT3 activators? (Methylene blue or resveratrol perhaps?) I did a quick google search and only came up with diet and exercise.

#4 health_nutty

  • Registered User
  • 2,380 posts
  • 86
  • Location:California

Posted 19 November 2010 - 07:05 PM

Yikes, I need to read the details, but a high fat diet decreased SIRT3 expression. I wonder if it is all kinds of fat or just certain types? Impossible to tell from this abstract.

Diet and exercise signals regulate SIRT3 and activate AMPK and PGC-1alpha in skeletal muscle.

OM Palacios, JJ Carmona, S Michan, KY Chen, Y Manabe, JL Iii, LJ Goodyear, Q Tong

SIRT3 is a member of the sirtuin family of NAD(+)-dependent deacetylases, which is localized to the mitochondria and is enriched in kidney, brown adipose tissue, heart, and other metabolically active tissues. We report here that SIRT3 responds dynamically to both exercise and nutritional signals in skeletal muscle to coordinate downstream molecular responses. We show that exercise training increases SIRT3 expression as well as associated CREB phosphorylation and PGC-1alpha up-regulation. Furthermore, we show that SIRT3 is more highly expressed in slow oxidative type I soleus muscle compared to fast type II extensor digitorum longus or gastrocnemius muscles. Additionally, we find that SIRT3 protein levels in skeletal muscle are sensitive to diet, for SIRT3 expression increases by fasting and caloric restriction, yet it is decreased by high-fat diet. Interestingly, the caloric restriction regimen also leads to phospho-activation of AMPK in muscle. Conversely in SIRT3 knockout mice, we find that the phosphorylation of both AMPK and CREB and the expression of PGC-1alpha are down regulated, suggesting that these key cellular factors may be important components of SIRT3-mediated biological signals in vivo.

Edited by health_nutty, 19 November 2010 - 07:06 PM.


#5 DaffyDuck

  • Registered User
  • 85 posts
  • 11

Posted 19 November 2010 - 08:46 PM

Not sure how well Kaempferol activates SIRT3 compared to other agents but it appears to be one of them. The good news is that sources of Kaempferol are simply foods known to be healthy. Green leafy vegetables and colored fruits. Apparently endives are rather rich in Kaempferol.


http://www.caspases....p?pmid=19160423

Kaempferol treatment increased the expression and the mitochondria localization of the NAD-dependent deacetylase SIRT3


http://onlinelibrary.../jcb.22044/full


Kaempferol induces apoptosis in two different cell lines via Akt inactivation, Bax and SIRT3 activation, and mitochondrial dysfunction





http://www.nature.com/ejcn/journal/v58/n6/full/1601916a.html


Endive is a rich source of kaempferol, containing up to 246 mg kaempferol per kg fresh weight (DuPont et al, 2000). Further, the majority of the kaempferol in endive is present as an uronic acid conjugate (kaempferol-3-glucuronide) rather than a glycoside



#6 health_nutty

  • Registered User
  • 2,380 posts
  • 86
  • Location:California

Posted 19 November 2010 - 09:52 PM

Endive is a rich source of kaempferol, containing up to 246 mg kaempferol per kg fresh weight (DuPont et al, 2000). Further, the majority of the kaempferol in endive is present as an uronic acid conjugate (kaempferol-3-glucuronide) rather than a glycoside



Thanks for the info.

Btw, it looks like kale is even bit higher at 26.74mg per 100g (although my source has endive at endive 4.04mg per 100g) 1

USDA Database for the Flavonoid Content of Selected Foods

#7 Logan

  • Registered User
  • 1,869 posts
  • 174
  • Location:Arlington, VA

Posted 19 November 2010 - 10:01 PM

AT1 antagonists activate SIRT3 and the CLOCK anti aging gene.


You taking any? I'm assuming that's why you know this. I'm interested.

#8 DaffyDuck

  • Registered User
  • 85 posts
  • 11

Posted 19 November 2010 - 10:08 PM

Found this interesting study showing that Kaempferol increases cell metabolism by increasing the action of Thyroid hormone and supposedly not via SIRT activation. I'm not sure it that is desirable or not or whether it is even correct.


http://diabetes.diab...t/56/3/767.full


Lastly, given that fisetin is a strong activator of the sirtuin pathway (24), we tested whether treatment with other potent sirtuin activators such as resveratrol, piaceatannol, or butein could affect D2 activity. Notably, all three compounds reduced D2 activity level to 25–60% of that of vehicle-treated cells, with resveratrol being the most active in this regard (Table 1). These results indicate that the effects of these small polyphenolic molecules on D2 are not the result of sirtuin activation.





Piaceatannol does not appear to activate SIRT3 but butein might.


Another interesting thing is that exposure to cold temperatures upregulates SIRT3, at lease in some cell types. Cold intolerance is a sign of decreased metabolism or hypothyroidism.

#9 medievil

  • Registered User
  • 3,335 posts
  • 20
  • Location:Belguim

Posted 19 November 2010 - 10:24 PM


AT1 antagonists activate SIRT3 and the CLOCK anti aging gene.


You taking any? I'm assuming that's why you know this. I'm interested.

Yeah i'm normally taking a combination of telmisartan and candesartan, currently not on any tough due to hypotension, wont add them back untill i'm back on amphetamine.

Here's my old thread about this:
http://www.imminst.o...xtend-lifespan/

And a full text of one of the study's:

Angiotensin receptors as determinants of life span.
Cassis P, Conti S, Remuzzi G, Benigni A.
Pflugers Arch. 2009 Sep 11. [Epub ahead of print]
PMID: 19763608

Angiotensin II (Ang II), the central product of renin-angiotensin system,
has a role in the etiology of hypertension and in pathophysiology of cardiac
and renal diseases in humans. Other functions of Ang II include effects on
immune response, inflammation, cell growth and proliferation, which are
largely mediated by Ang II type 1 receptor (AT(1)). Several experimental
studies have demonstrated that Ang II acts through AT(1) as a mediator of
normal aging processes by increasing oxidant damage to mitochondria and in
consequences by affecting mitochondrial function. Recently, our group has
demonstrated that the inhibition of Ang II activity by targeted disruption
of the Agtr1a gene encoding Ang II type 1A receptor (AT(1A)) in mice
translates into marked prolongation of life span. The absence of AT(1A)
protected multiple organs from oxidative damage and the alleviation of
aging-like phenotype was associated with increased number of mitochondria
and upregulation of the prosurvival gene sirtuin 3. AT(1) receptor
antagonists have been proven safe and well-tolerated for chronic use and are
used as a key component of the modern therapy for hypertension and cardiac
failure, therefore Ang II/AT(1) pathway represents a feasible therapeutic
strategy to prolong life span in humans.

Keywords Oxidative stress - Mitochondria - Aging - Angiotensin -
Inflammation

Abbreviation:

RAS
renin-angiotensin system
- Ang II
angiotensin II
- ACE
angiotensin converting enzyme
- AT1
Ang II type 1 receptor
- AT2
Ang II type 2 receptor
- NO
nitric oxide
- eNOS
endothelial nitric oxide synthase
- ROS
reactive oxygen species
- ACEi
angiotensin-converting enzyme inhibitors
- ARBs
angiotensin II receptor blockers
- SIRT
sirtuin
- Nampt
nicotinamide phosphoribosyltransferase
- IGF-1
insulin growth factor-1

Introduction

The mean life span has been increasing steadily over the course of human
evolution, and in the last century, the human life expectancy in developed
countries has nearly doubled as indicated by an increase from around 50 to
75-80 years [12]. Before 1950, most of the gain in life expectancy was due
to marked decrease in death rates at younger ages. In the second half of the
20th century, the observed reduction in mortality at ages above 65 years
could be ascribed to the delay in the onset of several age-related disorders
and to the increased capacity to prevent organ damage, as a consequence of
improved biomedical and nutritional conditions [47]. Therefore, ensuring
disease-free survival and not merely survival per se represents an
attractive and desirable goal for society as a whole. Healthy aging and
longevity depend on the dynamic interaction between biological and
environmental factors, including medical care, healthy diet, and lifestyle.
However, emerging evidence from model organisms has indicated that several
genetic factors might play a role in longevity, putting the attention on
several molecular candidates involved in pathways contributing to protect
organs from degeneration and diseases.

In the last 20 years, one of the main goals of our research was to find out
therapeutic strategies to protect the kidney from progressive renal injury
with the final aim to reduce the need of dialysis in patients. To this aim,
our efforts have been devoted to identify factors implicated in the
progression of chronic kidney disease, whose incidence is increasing
worldwide at an alarming rate. Experimental and clinical evidence is
available that blockade of the renin angiotensin system (RAS) by angiotensin
converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers
(ARB) is effective in slowing the progression of kidney disease due to the
drugs' ability to reduce proteinuria [53]. When ACEi and ARB were given in
combination to rats genetically predisposed to progressive nephropathy,
reduction of glomerular sclerosis was even more evident, particularly in
those glomeruli that had less severe lesion to begin with. This shows that
remodeling of glomerular architecture is possible, which would imply some
form of regeneration of the capillary network [53]. Recent clinical trials
suggested that inhibition of RAS might actually prevent nephropathy in
patients with chronic renal failure of nondiabetic origin (the Ramipril
Efficacy in Nephropathy study) [57]. The effectiveness of ACEi in protecting
the kidney against the development of microalbuminuria, which is a major
risk factor for cardiovascular events and death, has been also documented in
patients with type 2 diabetes (the Bergamo Nephrologic Diabetes
Complications Trial study) [56].

Strategies able to reduce renal disease progression could translate into a
decreased incidence of cardiovascular events. A tremendous body of research,
both experimental and clinical, has unequivocally shown that pharmacologic
blockade of RAS, beyond the renal protection, reduces cardiovascular risk
more effectively than other antihypertensive treatments [54]. Inhibition of
RAS prevents end-organ damage associated with aging [14], in line with
evidence that angiotensin II (Ang II) promotes the onset and the progression
of vascular senescence, associated with vascular, functional, and structural
changes contributing to age-related vascular disease [43].

In the present review, we focus on the recent emerging data suggesting a
role of Ang II in aging. In addition we highlight the mechanisms by which
Ang II via AT1 could affect life span in mammals.

The renin-angiotensin system

Renin-angiotensin system is considered to be the major regulator of blood
pressure and fluid homeostasis. The main effector molecule of the RAS, Ang
II, is produced from the substrate angiotensinogen through sequential
enzymatic cleavages by renin and angiotensin converting enzyme (ACE). In
particular renin cleaves angiotensinogen, forming Ang I that in turn is
converted to Ang II by ACE (Fig. 1). ACE is a circulating enzyme found in
the endothelial cells of the lung, vascular endothelium, and cell membranes
of the kidney, heart, and brain. ACE also degrades bradykinin to inactive
fragments, reducing the serum levels of endogenous vasodilators [8].

Ang II causes increases in systemic and local blood pressure via its
vasoconstrictive effect, influences renal tubuli to retain sodium and water,
and stimulates aldosterone release from adrenal gland [69]. Besides being a
potent vasoconstrictor, Ang II exerts several prominent nonhemodynamic
effects including proliferative, proinflammatory, and profibrotic activities
[58].

At the cellular level, responsiveness to Ang II is conferred by the
expression of two classes of pharmacologically distinct rhodopsin-like G
protein-associated receptors, the type 1 and the type 2 receptors (AT1 and
AT2) [61, 69]. AT1 has been cloned in a number of species and two subtypes
[59], named AT1A and AT1B, have been identified in rat and mouse. AT1A is
the predominantly expressed receptor in different body districts including
kidney, liver, heart, blood vessels, adrenal glands, and cardiovascular
control centers in the brain [11], and is considered the closest murine
homolog to the single human AT1. AT1A confers most of the classical actions
of Ang II such as blood pressure increase [36], aldosterone release from the
adrenal zona glomerulosa [1], salt retention in renal proximal tubuli [42],
and stimulation of the sympathetic nervous system via receptors in the brain
[17]. The expression of the AT1B appears to be more prominent in the
anterior pituitary gland and the adrenal zona glomerulosa. AT1B regulates
blood pressure when AT1A is absent [48].

The expression of the AT2 is high in the fetus, but low in adult tissues.
AT2 is expressed in the adrenal medulla, uterus, ovary, vascular
endothelium, and distinct brain areas [65]. AT2 interacts with and modulates
actions perpetuated by the AT1, possibly antagonizing many of its effects.
The binding of Ang II to the AT2 activates vasorelaxation of conduit and
resistant arteries and improves resistance artery remodeling, promotes
cardiovascular protection against ischemia-reperfusion injury and acute
myocardial infarction, inhibits cardiac fibrosis, and protects the kidney
from ischemic injury [60]. In a mouse model of renal ablation, the lack of
AT2 aggravates renal injury and reduces survival [6].

Link between angiotensin II and oxidative stress

Angiotensin II is known to contribute to oxidative stress damage by
stimulating the generation of both nitric oxide (NO) and NAD(P)H
oxidase-derived superoxide in the cytosol of different cell types including
endothelial, vascular smooth muscle, fibroblast and tubular epithelial cells
[51, 55]. The interaction between NO and superoxide generates peroxynitrite,
a cytotoxic anion that inhibits mitochondrial electron transport, destroys
DNA and cellular proteins, leading to oxidative stress damage [52].
Furthermore, Ang II can induce endothelial nitric oxide synthase (eNOS)
uncoupling, switching from NO to superoxide production [46]. Ang II
stimulates both cytosolic and mitochondrial reactive oxygen species (ROS)
generation [64] (Fig. 2). The direct interaction between Ang II and
mitochondrial components has been suggested by the presence of Ang II in
mitochondria of brain, heart, and smooth muscle cell in rodent [22];
moreover, renin, angiotensinogen, and ACE were also detected within
intramitochondrial dense bodies [50].

One of the most prominent theories to explain aging is the "free-radical
theory" of aging which was initially proposed by Harman in 1950 s [30]. It
postulates that the loss of cell functional capacity associated to
senescence results from the accumulation of ROS-inflicted oxidative stress
damage to different molecules, leading to lipid peroxidation, protein
oxidation and oxidative modifications in nuclear and mitochondrial DNA [21].

Reactive oxygen species are generated in multiple compartments and by
multiple enzymes within the cells, including NAD(P)H oxidases on plasma
membranes, lipid metabolism within the peroxisomes, and various cytosolic
enzymes such as cyclooxygenase. The majority of intracellular ROS production
derives from mitochondrial matrix and the space between the inner and outer
mitochondrial membrane. Mitochondria utilize more than 90% of cellular
oxygen to produce energy. While most oxygen is transformed into water, 1-2%
of it forms superoxide [7]. Reactive oxygen species compromise mitochondrial
integrity and function, leading to a decreased mitochondrial ATP generation,
with a subsequent increased release of ROS by the mitochondria themselves,
initiating a vicious cycle of progressively increasing oxidative stress
[23]. The aging process is frequently associated to a reduction in
mitochondrial number and several changes in mitochondrial structure, such as
swelling, shortening of the cristae, and matrix vacuolization [10, 31, 67].

Under normal physiological conditions, the capacity of Ang II to promote
oxidative stress is tightly regulated [20, 27]. By contrast, in conditions
associated with RAS overactivation, such as aging [3, 68, 70], the
dysregulation of Ang II-dependent ROS generation may become a significant
contributor to cell oxidation and tissue damage. RAS overactivation exerts
deleterious effects on renal and cardiac functions documented by the
increase of Ang II peptide in urines [25] and increased generation of Ang II
in the heart [28] of old animals. A recent in vitro study has demonstrated
that the production of ROS induced by Ang II via AT1 led to DNA damage, and
consequently to accelerated aging of human vascular smooth muscle cells
[32]. Cell senescence following ROS production has been proposed to be
mediated by two different mechanisms of DNA damage: a telomere-independent
pathway via the induction of stress induced premature senescence (SIPS) and
a telomere-dependent mechanism via accelerated attrition of telomeres. This
hypothesis has been confirmed by data showing that the critical DNA damage
induced by AT1-mediated ROS production both increased SIPS expressions that
promoted cell cycle arrest and markedly accelerated the rate of telomere
loss that is associated with reduced cellular proliferation and premature
cell senescence [32].

All these findings demonstrate the crucial role of oxidative stress on the
aging process and strongly support the involvement of Ang II in tissue
senescence by virtue of its ability to mediate the release of oxidant
species.

Protective effect of inhibiting angiotensin II on aging

Angiotensin-converting enzyme inhibitors and ARBs are two widely used
classes of anti-hypertensive drugs that inhibit RAS at different levels.
ACEi inhibit Ang II formation by binding to the active site of the enzyme
that converts Ang I into Ang II, and ARBs prevent Ang II from binding to its
receptors.

In aging animals, the cardiovascular protective effects occurred after RAS
inhibition was associated with an increased NOS activity [26]. Moreover, in
old animals, both enalapril and losartan treatments significantly increased
NO production in heart homogenate, while reduced hydrogen peroxide formation
[15]. In spontaneously hypertensive rats, the inhibition of RAS was able to
reverse the naturally age-related and advanced myocardial hypertrophy and
fibrosis by attenuating Ang II-mediated oxidative stress, as documented by
reduced expression of NAD(P)H oxidative components p22phox, p47phox, and
gp91phox in old hearts [37]. Furthermore, oxygen radicals mediated the
accelerated cerebral endothelial dysfunction that occurs with age, and more
importantly, old mice lacking AT1 did not develop these age-related cerebral
circulation damages [45].

Other studies performed in normal adult rats have clearly shown that chronic
treatment with ACEi or ARB reduced kidney damage associated with age. Old
animals treated with enalapril and losartan presented lower glomerular and
tubulointerstitial fibrosis, reduced monocyte or macrophage infiltrates, and
decreased tubular atrophy than untreated aged animals [24].

The beneficial effect of RAS inhibition involves the preservation of renal
mitochondria from aging in rats. Enalapril and losartan treatments prevented
the age-associated decline in the renal mitochondrial capacity for energy
production and attenuated the age-associated increase in mitochondrial
oxidant production [19].

A similar protective effect of RAS inhibition was also observed in the liver
from old rats. In these animals the maintenance of an adequate mitochondrial
function during aging was due to the enhanced transcription levels of the
genes nuclear respiratory factor 1 and peroxisome proliferators activator
receptor gamma coactivator-1alpha that are involved in mitochondrial
respiration and biogenesis, respectively. These positive effects on
mitochondria maintained the integrity of the hepatocyte system, and
prevented liver fibrosis and the infiltration of inflammatory cells during
aging [18].

The development of gene-targeting technology in mice has provided new
insight into the role of RAS genes in regulating blood pressure, body fluid
homeostasis, and fetal development. Mice that are unable to generate Ang II
because of targeted mutation in the angiotensinogen (Agt -/-) or
angiotensin-converting enzyme (Ace -/-) genes had a severe phenotype
characterized by reduced survival, low blood pressure, and abnormal kidney
morphology. A similar phenotype was observed in mice lacking both Ang II
type 1 receptors (AT1A-/- AT1B-/-) [49].

The disruption of the gene encoding AT1A (Agtr1a) -- the major mouse AT1
receptor isoform -- did not cause severe postnatal mortality or the
structural abnormalities seen in the kidneys of the knockout models
described above. Taking advantage from this mouse model, we have recently
investigated the role of the AT1 in end-stage organ damage. A prospective
observational study was performed in homozygous mice deficient for the AT1A
and wild-type controls. AT1A-/- mice substantially outlived their wild-type
littermates by 26% (Fig. 3) and had normal body weight and physical activity
as reflected by their ability to perform on a rotating system that evaluates
motor coordination and vitality. Reduction in food intake of 20% and 40% in
laboratory animals extends their life span by up to 50% [29]. Reduced
caloric intake did not contribute to prolonged survival in AT1A-/- mice,
since daily food intake was virtually identical between AT1A-/- and
wild-type mice. AT1A-/- grew up normally, and the body weights increased
comparably to wild-type littermates ruling out the possibility that small
body size could be responsible of extended life span as previously described
[9].

Aging AT1A-/- mice developed fewer aortic atherosclerotic lesions and less
cardiac injury, as reflected by the reduction of myocyte size and fibrosis,
with lower deposition of interstitial collagen with respect to wild-type
mice [5]. These data point to a direct effect of Ang II via AT1A on
atherosclerotic lesion generation and on extracellular matrix deposition by
cardiac fibroblasts.

Furthermore, aging mice lacking the AT1A showed reduced production of
peroxinitrite in hearts and aortas, as compared to wild-type animals,
indicating a possible role of Ang II via AT1A into the production of ROS
[5]. Given the crucial role of mitochondria in producing peroxynitrite
during aging processes [39], ultrastructural analysis of mitochondria was
performed in proximal tubular cells of the kidney of AT1A-/- mice that
possess a large number of mitochondria and are highly dependent on
mitochondrial energy production for proper function [33]. The lack of AT1A
protected the cells from the loss of mitochondria during aging [5],
demonstrating that Ang II negatively influences mitochondrial number and
function by promoting oxidative stress, and that the absence of AT1A
strongly attenuated the functional and structural changes that occur in
kidney mitochondria following oxidative stress increase upon age [5].

Role of sirtuins in longevity associated with AT1A-/- mice

Recent evidences have suggested that mitochondrial activity could be
regulated by the expression of enzymes belonging to the Sirtuin family [16].
Sirtuins are nicotinamide adenine dinucleotide (NAD)-dependent deacetylases
proteins highly conserved from Escherichia Coli to humans and associated
with longevity, mitochondrial and cell cycle regulation, apoptosis, and DNA
damage repair [29]. In humans and mice, there are seven different sirtuins
(SIRT1-7), and three are located in the mitochondria (SIRT3, 4, and 5).
Among them, SIRT3 has an apparent direct link to extended life span in
humans, in fact mutations in an enhancer region of the Sirt3 gene that
potentially upregulate its expression were found at a high frequency in
long-lived individuals [4]. Under oxidative stress, SIRT3 overexpression
protects the cardiomyocytes against Bax-mediated apoptosis by deacetylating
the substrate Ku70, promoting the binding of Ku70 to Bax, and hence blocking
the Bax activation [66]. Of note, SIRT3 regulates adaptive thermogenesis and
decreases mitochondrial membrane potential and reactive oxygen species
production, while increasing cellular respiration [62]. For these reasons
SIRT3 acts as sensor of small reactive oxygen species that could lead to
mitochondrial damage and activates specific cellular signaling pathway to
counteract oxidative stress such as the expression of MnSOD antioxidant
protein [38]. The recent identification of the two substrates such as acetyl
coenzyme A synthetase and glutamate dehydrogenase as targets of SIRT3
revealed that this molecule controls a regulatory network involved in energy
metabolism and in mechanisms of caloric restriction and life span
determination [40, 41].

SIRT3 could exert its action only in the presence of the cosubstrate NAD+,
and the concentration of NAD+ determines cell survival. In the context of
nutrient restriction, mitochondria dictate cell survival through the
upregulation of nicotinamide phosphoribosyltransferase (Nampt) that boosts
mitochondrial NAD+ concentration [71]. Altogether these findings prompted us
to study Sirt3 and Nampt survival genes in AT1A-/- mice. Transcript levels
of both Nampt and Sirt3 were increased in kidneys from AT1A-/- mice with
respect to wild-type animals. The finding that candesartan, an AT1 receptor
antagonist, prevented Ang II-induced Nampt and Sirt3 mRNA reduction in
cultured tubular epithelial cells suggested a possible biochemical link
between Ang II and survival genes, which conceivably operates via the AT1A.
Furthermore, experiments showing that Nampt gene silencing by siRNA limited
the reduction of Sirt3 mRNA induced by Ang II would indicate a causative
role of Nampt in modulating Sirt3 gene transcription in response to Ang II
[5].

Caloric restriction prolongs the life span through an increase of sirtuins
[29, 63]. In rodents and humans the levels of Sir2 ortholog SIRT1, that
targets numerous regulatory factors affecting stress management and
metabolism, increase in response to caloric restriction and this increase
causes favorable changes in metabolism and stress tolerance [13].

The sirtuins are also involved in prolonged survival induced by resveratrol
[2], a small molecule found in red wine which activates SIRT1 and mimics the
anti-aging effect of caloric restriction. The effect of resveratrol on life
span is associated with increased mitochondrial number and is dependent on
the upregulation of Sir2 [35]. Moreover, resveratrol downregulates AT1
through SIRT1 activation in cultured vascular smooth muscle cells and mouse
aorta implying that inhibition of the AT1 contributes to resveratrol-induced
longevity [44].

In the kidney from AT1A-/- mice the levels of SIRT1 were comparable to
wild-type mice, suggesting that the increased longevity of this mouse strain
is independent from the SIRT1 pathway.

All these findings support a role of SIRT3 in the prolongation of life span,
and the manipulation of the RAS system provides a remarkable beneficial
effect on longevity by reducing oxidative stress and upregulating survival
genes (Fig. 4).

Conclusions

Chronic activation of RAS plays an important role in the promotion of
end-stage organ damage associated with aging by increasing tissue and
mitochondrial oxidative stress. Therapies targeting RAS (ACEi and ARBs)
reduce age-associated cardiovascular and renal damage and preserve the
number and the function of mitochondria. A stronger protective effect,
demonstrated by a significant prolongation of life span, was observed in
genetically modified mice, which lack the AT1A gene. In these mice, the
longevity is the consequence of reduced mitochondrial damage due to the
attenuation of oxidative stress and the upregulation of Nampt and Sirt3
survival genes.

The extension of the life span observed in AT1A-/- mice is comparable to
that of mice lacking the insulin growth factor-1 (IGF-1) receptor [34].
However the manipulation of the latter pathway in humans is not imminently
feasible. In contrast, Ang II type 1 receptor antagonists have been proven
safe, well-tolerated for chronic use and represent a key component of the
modern therapy for hypertension and cardiac failure. Thus, the inhibition of
AT1 could represent a possible therapeutic strategy for diseases of aging
and possibly for extending the life span. Further studies are necessary to
deepen the role of AT1 in humans and to understand whether the receptor
function is similar to that found in animals.



#10 maxwatt

  • Member, Moderator
  • 4,564 posts
  • 1,421
  • Location:New York

Posted 19 November 2010 - 11:21 PM

Resveratrol does, in fact, up-regulate SIRT3"

Phytother Res. 2008 Oct;22(10):1367-71.
Resveratrol induces apoptosis and inhibits adipogenesis in 3T3-L1 adipocytes.
Rayalam S, Yang JY, Ambati S, Della-Fera MA, Baile CA.

Department of Animal & Dairy Science, University of Georgia, Athens, GA 30602-2771, USA.
Abstract
Resveratrol, a phytoallexin, has recently been reported to slow aging by acting as a sirtuin activator. Resveratrol also has a wide range of pharmacological effects on adipocytes. In this study, we investigated the effects of resveratrol on adipogenesis and apoptosis using 3T3-L1 cells. In mature adipocytes, 100 and 200 microM resveratrol decreased cell viability dose-dependently by 23 +/- 2.7%, and 75.3 +/- 2.8% (p < 0.0001), respectively, after 48 h treatment, and 100 microM resveratrol increased apoptosis by 76 +/- 8.7% (p < 0.0001). Resveratrol at 25 and 50 microM decreased lipid accumulation in maturing preadipocytes significantly by 43 +/- 1.27% and 94.3 +/- 0.3% (p < 0.0001) and decreased cell viability by 25 +/- 1.3% and 70.4 +/- 1.6% (p < 0.0001), respectively. In order to understand the anti-adipogenic effects of resveratrol, maturing 3T3-L1 preadipocytes were treated with 25 microM resveratrol and the change in the expression of several adipogenic transcription factors and enzymes was investigated using real-time RT-PCR. Resveratrol down-regulated the expression of PPAR gamma, C/EBP alpha, SREBP-1c, FAS, HSL, LPL and up-regulated the expression of genes regulating mitochondrial activity (SIRT3, UCP1 and Mfn2). These results indicate that resveratrol may alter fat mass by directly affecting cell viability and adipogenesis in maturing preadipocytes and inducing apoptosis in adipocytes and thus may have applications for the treatment of obesity.

© 2008 John Wiley & Sons, Ltd.
PMID: 18688788



#11 JLL

  • Registered User
  • 2,192 posts
  • 156

Posted 20 November 2010 - 07:57 PM

If resveratrol upregulates SIRT3, why doesn't resveratrol extend lifespan in healthy mice?

#12 maxwatt

  • Member, Moderator
  • 4,564 posts
  • 1,421
  • Location:New York

Posted 20 November 2010 - 09:54 PM

If resveratrol upregulates SIRT3, why doesn't resveratrol extend lifespan in healthy mice?

Whatever it is mice die of, resveratrol did not protect against that. It's not like "aging" is one thing. It is a collection of insults to an organism/

SIRT3 is a mitochondrial sirtuin, and resveratrol did increase the number and size of mitochondria in the muscle tissue of mice. There is some evidence it does the same in humans, and could be a useful treatment for sarcopenia, the weakening and wasting of muscle in aging humans.

Some researchers have come up with an assay for SIRT1 activation which does not use the fluorophone in the original Biomol assay; Sirt1 activation was thought to be an artifact of the assay, and not due to resveratrol. Their measurements obtained very different results. The were looking primarily at inhibition of SIRT1, and found a better inhibitor than Sirtinol. They also looked at activation. While they found resveratrol did activate SIRT1, it was weaker than the activation by either fisetin or piceatannol. They found that quercetin inhibited Sirt1. They used their assay to measure some 32 compounds. I've been meaning to post this paper, if there is interest in it. It does look as if several other flavonols, stilbenes and flavones are worth investigating.

The full text is available HERE.

J Pharmacol Sci. 2008 Nov;108(3):364-71. Epub 2008 Nov 13.
A novel chalcone polyphenol inhibits the deacetylase activity of SIRT1 and cell growth in HEK293T cells.
Kahyo T, Ichikawa S, Hatanaka T, Yamada MK, Setou M.

Mitsubishi Kagaku Institute of Life Sciences (MITILS), Machida, Tokyo, Japan. aynoken@mitils.jp
Abstract
SIRT1 is one of seven mammalian orthologs of yeast silent information regulator 2 (Sir2), and it functions as a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase. Recently, resveratrol and its analogues, which are polyphenols, have been reported to activate the deacetylase activity of SIRT1 in an in vitro assay and to expand the life-span of several species through Sir2 and the orthologs. To find activators or inhibitors to SIRT1, we examined thirty-six polyphenols, including stilbenes, chalcones, flavanones, and flavonols, with the SIRT1 deacetylase activity assay using the acetylated peptide of p53 as a substrate. The results showed that 3,2',3',4'-tetrahydroxychalcone, a newly synthesized compound, inhibited the SIRT1-mediated deacetylation of a p53 acetylated peptide and recombinant protein in vitro. In addition, this agent induced the hyperacetylation of endogenous p53, increased the endogenous p21CIP1/WAF1 in intact cells, and suppressed the cell growth. These results indicated that 3,2',3',4'-tetrahydroxychalcone had a stronger inhibitory effect on the SIRT1-pathway than sirtinol, a known SIRT1-inhibitor. Our results mean that 3,2',3',4'-tetrahydroxychalcone is a novel inhibitor of SIRT1 and produces physiological effects on organisms probably through inhibiting the deacetylation by SIRT1.

PMID: 19008647



#13 curious_sle

  • Registered User
  • 454 posts
  • 11
  • Location:Switzerland

Posted 25 November 2010 - 10:54 AM

Am i mistaken in seeing oxaloacetic acid (Benagene) as a potential sort3 activator?
( http://www.ncbi.nlm....les/PMC2841477/ nadh/nad+ ratio as inducer, thats what benagene does, eh? )

Opinions?

#14 JLL

  • Registered User
  • 2,192 posts
  • 156

Posted 25 November 2010 - 10:39 PM

Can someone explain to me why HDAC inhibitors are often mentioned in anti-aging studies as a good thing, and yet sirtuins are HDACs. If activating Sirt3 is what we're after, wouldn't HDAC inhibitors be a bad idea? I'm confused.

#15 AdamI

  • Registered User
  • 175 posts
  • 4
  • Location:Oslo

Posted 01 February 2013 - 10:26 AM

New study on SIRT3
SIRT3 Reverses Aging-Associated Degeneration
http://www.cell.com/...2-0?script=true

#16 hav

  • Member
  • 942 posts
  • 163
  • Location:Cape Cod
  • no

Posted 01 February 2013 - 06:10 PM

New study on SIRT3
SIRT3 Reverses Aging-Associated Degeneration
http://www.cell.com/...2-0?script=true


I thought the most interesting part of the paper was the section: "SIRT3 Upregulation Rescues Functional Defects of Aged HSCs". But although I reread it a few times, I couldn't pick up on exactly how they triggered the upregulation

Howard

#17 AdamI

  • Registered User
  • 175 posts
  • 4
  • Location:Oslo

Posted 01 February 2013 - 06:40 PM

Neither did I. Soo should one start taking SOD2 now:)?
This was news in swedish media soo thought this place would like to read it. But seems rather dead here on Longecity. Is it all old news or just the wrong thread?

#18 Kevnzworld

  • Registered User
  • 761 posts
  • 254
  • Location:Los Angeles

Posted 01 February 2013 - 07:07 PM

Neither did I. Soo should one start taking SOD2 now:)?
This was news in swedish media soo thought this place would like to read it. But seems rather dead here on Longecity. Is it all old news or just the wrong thread?


Sirt3 upregulates SOD 2, not the reverse.
Quote:
" Prominently, SIRT3 regulates the global acetylation landscape of mitochondrial proteins, and SIRT3-initiated metabolic adapta- tions enhance mitochondrial management of ROS. SIRT3 increases the activity of antioxidants, such as superoxide dismu- tase 2 (SOD2) and reduced glutathione, and promotes ROS scavenging (Qiu et al., 2010; Someya et al., 2010; Tao et al., 2010). Additionally, SIRT3 initiates metabolic reprogramming toward more efficient electron transport and fuel usage away from carbohydrate catabolism, which is thought to result in reduced ROS production (Ahn et al., 2008; Hirschey et al., 2010). Thus, SIRT3 provides a unique tool to understand mito- chondrial metabolism and management of ROS. "


#19 niner

  • Member, Moderator
  • 14,617 posts
  • 3,546
  • Location:Philadelphia

Posted 01 February 2013 - 07:51 PM

I thought the most interesting part of the paper was the section: "SIRT3 Upregulation Rescues Functional Defects of Aged HSCs". But although I reread it a few times, I couldn't pick up on exactly how they triggered the upregulation


It was done by genetic engineering, so there's nothing I know of that we can take to upregulate SIRT3. We could starve ourselves; that would do it...

Soo should one start taking SOD2 now:)?


No. They did use an in vitro dose of NAC to rescue sirt3 knockout cells. C60-oo would probably work better in a human to compensate for inadequate SIRT3 expression, at least some of the downstream effects of it. It wouldn't, however, be expected to increase expression of SIRT3.

#20 ihatesnow

  • Registered User
  • 661 posts
  • 238
  • Location:rochester new york

Posted 02 February 2013 - 07:56 AM

http://news.discover...red-1301311.htm

#21 prophets

  • Registered User
  • 1,778 posts
  • 157
  • Location:US

Posted 02 February 2013 - 08:38 AM

IDK why people aren't focused on SIRT3/AMPK more.

this forum has like 100 pages worth of this buckyballs craziness... most likely just another bunch of crap that some huckster can stick in a bottle and sell to people at $49.99.

#22 niner

  • Member, Moderator
  • 14,617 posts
  • 3,546
  • Location:Philadelphia

Posted 02 February 2013 - 02:43 PM

IDK why people aren't focused on SIRT3/AMPK more.

this forum has like 100 pages worth of this buckyballs craziness... most likely just another bunch of crap that some huckster can stick in a bottle and sell to people at $49.99.


I don't blame you for thinking that if you haven't looked into it at all, but you have it backwards. This SIRT3 paper is all over the media, and it's a cool thing and all, but actionable relevance to humans today? Zero. Maybe someday.

On the other hand, c60-oo is a paradigm shift. It has profound physiological effects in humans. There are a number of disease states where it would make a big difference. In some cases, a major, life-altering difference. This is real, not hype. This is not resveratrol. Interestingly, is there any "hype" in the media about c60? Precious little. A few mentions, then nothing. Maybe that should tell you something, what with the media being something of a contrary indicator.

#23 prophets

  • Registered User
  • 1,778 posts
  • 157
  • Location:US

Posted 02 February 2013 - 06:50 PM

I don't blame you for thinking that if you haven't looked into it at all, but you have it backwards. This SIRT3 paper is all over the media, and it's a cool thing and all, but actionable relevance to humans today? Zero. Maybe someday.


I read the French study 2x. The best I can say about it is that it is interesting and I hope it gets repeated (hopefully by someone with enough of a brain to use a study population of N=30, and not 6 rats only). I personally find the paper to be very suspect. Anyone who is supplementing based on that paper is really taking a leap of faith, IMO.

As for SIRT3, I'm not sure I agree there is nothing that can be done.

Edited by prophets, 02 February 2013 - 06:57 PM.

  • like x 1

#24 niner

  • Member, Moderator
  • 14,617 posts
  • 3,546
  • Location:Philadelphia

Posted 02 February 2013 - 07:37 PM


I don't blame you for thinking that if you haven't looked into it at all, but you have it backwards. This SIRT3 paper is all over the media, and it's a cool thing and all, but actionable relevance to humans today? Zero. Maybe someday.


I read the French study 2x. The best I can say about it is that it is interesting and I hope it gets repeated (hopefully by someone with enough of a brain to use a study population of N=30, and not 6 rats only). I personally find the paper to be very suspect. Anyone who is supplementing based on that paper is really taking a leap of faith, IMO.


They got a little sloppy and made some mistakes in the figures, which have since been corrected. Moussa is legit- he's been working with fullerenes for a long time. The small number of animals is irrelevant because the effects are so huge and so consistent. You only need large numbers of animals when the effects are small and variable. The experiment will be repeated (people here are already working on that), but I'm not waiting five years before I avail myself of this substance. "Leap of faith"? I don't know- fullerenes have been in a lot of different organisms, with consistently good results, and now they've been in thousands of humans. Some of the human results are shockingly good. I don't really care if it does or doesn't increase human lifespan- I've felt the effects. Any LE will be icing on the cake.

As for SIRT3, I'm not sure I agree there is nothing that can be done.


Well, we can starve ourselves. But we already knew about that. I don't see what else we can do with it today, outside of a molecular biology lab. Maybe someday there will be a compound that upregulates it or increases its activity in some way.

#25 xEva

  • Registered User
  • 932 posts
  • 469
  • Location:USA

Posted 03 February 2013 - 06:29 AM

Fasting, cold and moderate exercise upregulate SIRT3.

Some quotes:
  • The sirtuin family has emerged as key regulators of the nutrient-sensitive metabolic regulatory circuit. [1]
  • SIRT3 initiates metabolic reprogramming toward more efficient electron transport and fuel usage away from carbohydrate catabolism [1].
  • Proteomics analysis of mitochondrial proteins revealed the acetylation levels of numerous mitochondrial proteins change during fasting. The dependence of SIRT3 enzymatic activity on NAD+ suggests that SIRT3 could serve as a metabolic sensor and couples the energy status of the cell with the level of mitochondrial protein acetylation. [2]
  • acetylation as a novel regulatory mechanism for mitochondrial fatty acid oxidation and demonstrate that SIRT3 modulates mitochondrial intermediary metabolism and fatty acid utilization during fasting.[2]
  • SIRT3 functions to trigger mitochondrial reprogramming toward reduced oxidative stress.[1]
  • While hepatic SIRT3 expression was low under basal conditions, its expression was induced during fasting. The increase in SIRT3 protein expression during fasting was concomitant with a relative decrease in the acetylation levels of some mitochondrial proteins, suggesting that SIRT3 mediated their deacetylation. [2]

  • overexpression of SIRT3 increases oxygen consumption [3]

  • metformin downregulates SIRT3 expression in the liver and this results in increased mitochondrial protein acetylation. [3]
  • Metformin prevented induction of SIRT3 by glucagon and also reduced SIRT3 expression per se in mouse primary hepatocytes. A similar effect was observed in vivo. By contrast, but in agreement with previous studies, SIRT1 was upregulated by the drug. These findings indicate that metformin distinctively regulates exp<b></b>ression of different Sirtuin family members. [3]
  • Because of SIRT3 enzymatic function as a mitochondrial deacetylase, its lower expression should lead to stronger mitochondrial acetylation. Indeed, acetylation of several mitochondrial proteins was enhanced, suggesting that metformin can regulate mitochondrial function through a SIRT3-mediated mechanism, and this may contribute to a reduced intracellular ATP level. This was further supported by the fact that overexpression of SIRT3 in HepG2 attenuated the inhibitory effect of metformin on ATP synthesis. Furthermore, SIRT3 overexpression increased the ATP/ADP ratio.[3]

[1] SIRT3 Reverses Aging-Associated Degeneration. 2013. http://www.cell.com/...eports/fulltext

[2] SIRT3 regulates fatty acid oxidation via reversible enzyme deacetylation. 2010. http://www.ncbi.nlm....les/PMC2841477/

[3] Metformin Reduces Hepatic Exp<b></b>ression of SIRT3, the Mitochondrial Deacetylase Controlling Energy Metabolism. http://www.plosone.o...al.pone.0049863

PS

1. Why OP's first post is downvoted?

2. What's up with the code inserting <b><b> in the middle of e.x.p.r.e.s.s.i.o.n? It's very annoyng.

#26 xEva

  • Registered User
  • 932 posts
  • 469
  • Location:USA

Posted 03 February 2013 - 08:57 AM

SIRT3 Controls Cancer Metabolic Reprogramming by Regulating ROS and HIF

Cancer Cell. 2011 March 8; 19(3): 299–300.
doi: 10.1016/j.ccr.2011.03.001
http://www.ncbi.nlm....les/PMC3087169/

Quotes:
  • ...genetic loss of the deacetylase SIRT3 leads to metabolic re-programming toward glycolysis. This shift is mediated by an increase in cellular reactive oxygen species (ROS) generation that amplifies HIF-&alpha; stabilization and HIF-dependent gene exp<b></b>ression, thereby driving the tumor phenotype.
  • ... genetic deletion of SIRT3 pushes the cell in the direction of oncogenic transformation.
  • SIRT3 functions as a tumor suppressor. The mechanistic basis for SIRT3's tumor-suppressive role seems to reside in its ability to regulate reactive oxygen species (ROS) generation or clearance by the cell. Kim et al. noted that ROS levels were increased in SIRT3-/- cells, as a consequence of a decreased exp<b></b>ression of antioxidant enzymes such as catalase and MnSOD. The transcription factor FOXO3a plays an important role in regulating the exp<b></b>ression of MnSOD and other antioxidants, and SIRT3-mediated deacetylation of FOXO3a promotes its nuclear localization. Thus, loss of SIRT3 activity suppresses FOXO3a, leading to an increase in cellular ROS signaling. Enhanced ROS levels have been linked to cancer, and Kim et al. observed an increase in the incidence of mammary tumors in the SIRT3 knockout mice.
  • The loss of SIRT3 appears to drive HIF activation even under basal normoxic conditions, and to enhance the HIF response to hypoxia through a ROS-dependent mechanism. Treatment of SIRT3 knockout cells with the antioxidant, N-acetyl cysteine (NAC), returns the normoxic HIF to wild type levels
  • over-exp<b></b>ression of SIRT3 shifts the cell away from the Warburg effect and suppresses the hypoxic response
  • Finley et al. provide correlative evidence showing an association between the loss of SIRT3 in human breast cancers and the enhanced exp<b></b>ression of HIF-1-dependent genes.

Regulation of tumor cell phenotype by SIRT3.


Posted Image



#27 xEva

  • Registered User
  • 932 posts
  • 469
  • Location:USA

Posted 03 February 2013 - 09:01 AM

PS
_____________________________________________________________

More and more reasons to start starving ourselves on a regular basis

..while running barefoot on the snow..

Living longer has just become more fun :)

Edited by xEva, 03 February 2013 - 09:04 AM.

  • like x 1

#28 Mind

  • Lifetime Member, Moderator, Secretary
  • 13,402 posts
  • 3,814
  • Location:Wausau, WI
  • yes

Posted 03 February 2013 - 12:56 PM

C60 is pretty safe - according to the published literature, so it has that going for it as well. I don't take it, but I have given it to one of my cats.

#29 mikeinnaples

  • Registered User
  • 1,671 posts
  • 256
  • Location:Florida

Posted 04 February 2013 - 04:27 PM

So I found and read this while trying to understand this a little better: http://lab.hirschey....cetylation.html

At one point it directly says that both fasting and calorie restricted mice display an increase in mitochondrial protein acetylation. Then I read this up above: metformin downregulates SIRT3 expression in the liver and this results in increased mitochondrial protein acetylation. Then knowing the research out there about metformin decreasing certain cancer risk, I see above that it reduces SIRT3 expression and that SIRT3 is a tumor suppressor (and actual deletion is oncogenic).

This seems a little contradictory to me and I want to make sure I understand what this means in regards to metformin. As this isn't my field of expertise, can someone explain it to me in layman's terms? Thanks

sponsored ad

  • Advert

#30 mikeinnaples

  • Registered User
  • 1,671 posts
  • 256
  • Location:Florida

Posted 05 February 2013 - 01:38 PM

I guess nobody knows?





Also tagged with one or more of these keywords: new research

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users