Manifestation of Novel Social Challenges of the European Unionin the Teaching Material ofMedical Biotechnology Master’s Programmesat the University of Pécs and at the University of DebrecenIdentification number: TÁMOP-4.1.2-08/1/A-2009-0011

MOLECULAR / CELLULAR EFFECTS OF ACUTE AND CHRONIC STRESS –METABOLISM AND LONGEVITY PART II

Krisztián KvellMolecular and Clinical Basics of Gerontology – Lecture 24

Manifestation of Novel Social Challenges of the European Unionin the Teaching Material ofMedical Biotechnology Master’s Programmesat the University of Pécs and at the University of DebrecenIdentification number: TÁMOP-4.1.2-08/1/A-2009-0011

TÁMOP-4.1.2-08/1/A-2009-0011

Energy intake relative to control animals (%)

1.00

1.10

1.20

1.30

1.40

1.50

1.60

20 30 40 50 60 70 80 90 100

y = -0.0083x + 1.8321r2 = 0.9593P < 0.000

Prop

ortio

nate

incr

ease

in su

rviv

alov

er c

ontro

l ani

mal

sCR increases life-span

TÁMOP-4.1.2-08/1/A-2009-0011

Non-CR

65% CR55% CR25% CR

Surv

ival

(%)

Age (months)0 10 20 30 40 50 60

25

75

100

0

50

Lifespan increase due to CR

TÁMOP-4.1.2-08/1/A-2009-0011

• Reducing food-consumption by 30-50% increases mean and maximum life-span

• Opposes cancers, diabetes, renal disease, cardiovascular disease, neuronal diseases

• Major mechanism of action: decrease in ROS production (reduced mitochondrial proton leak)

CR extends life-span

TÁMOP-4.1.2-08/1/A-2009-0011

Ad libitum

NAD/NADH

AC Substrate Substrate

PNC1NA

SIR2

Glucose

Glycolysis

Calorie restriction

NAD/NADH

Respiration

AC Substrate Substrate

PNC1 NA

SIR2

Glucose

Glycolysis

Sirtuin switch inad libitum and CR mice

TÁMOP-4.1.2-08/1/A-2009-0011

• Insulin / IGF1 signaling pathway• Sirtuin signaling pathway• Redox signaling pathway• TOR signaling pathway

CR extends life-span via:

TÁMOP-4.1.2-08/1/A-2009-0011

• Subset of daf genes dramatically increase life-span

• Main target is daf 16 that is highly homologous with Foxo

• Insulin and growth-factor reduction shifts Foxo proteins to nucleus

• CR induces 50% decrease in insulin plasma levels

• CR induces 20% decrease in plasma IGF1 levels

Insulin / IGF signaling pathway

TÁMOP-4.1.2-08/1/A-2009-0011

• Snell and Ames mice (lack of GH, PRL, TSH) have increased life-span

• GHRH, GHR, IGF1R deficient mice have increased life-span

• p66shc (IGF1R substrate) deficient mice have increased life-span

• Klotho (IGF1-repressor)-transgenic mice have increased life-span

Proof of GH / IGF signaling axis in aging

TÁMOP-4.1.2-08/1/A-2009-0011

Liver

White AdiposeTissue

Pancreatic β cell

Resveratrol

Fasting

CR SIRT1

Insulin secretion

Mithocondrial biogenesis Oxidative capacityFatty acid oxidation Glucose utilization

Fat mobilization Adipogenesis

Sceletal muscle

SIRT1 N-CoR/SMRT

PPARγ

FOXO1 AC

FOXO1 AC

PGC-1α ACFOXO1 AC

?

The mechanism of action for sirtuins

UCP2

GluconeogenesisGlycolysis

Fatty acid oxidationPPARα

PPARγPGC-1α HNF-4α

PGC-1αAC

FOXO1PGC-1α

AC

FOXO1 AC

?

TÁMOP-4.1.2-08/1/A-2009-0011

• Sir2 family proteins, called ‘sirtuins’• Regulation of transciptional silencing• Silences telomeres, rDNA repeats• Component of RENT silencer at telomeres• Forms heterochromatin• ADP-ribosyl transferase activity• H4-specific deacetylase (NAD-dependent)• Energy sensor, links metabolism and aging

Features of Sir2 family

TÁMOP-4.1.2-08/1/A-2009-0011

• Highly conserved enzymatic core domain • Mediates life-extending effects of CR• Mammals have 7 sirtuins, Sirt 1-7• Sirt1 shows highest homology with yeast

Sir2

Sirtuins as regulators for aging

TÁMOP-4.1.2-08/1/A-2009-0011

• Pancreas: improves glucose tolerance and insulin sensitivity, represses Ucp2, deacetylates Foxo1

• Liver: promotes gluconeogenesys and inhibits glycolysis, deacetylates PGC-1a

• Fat (WAT): interacts and represses PPARg, increases adiponectin secretion

Sirt1 as regulator for aging I

TÁMOP-4.1.2-08/1/A-2009-0011

• Muscle: regulates glucose uptake and insulin sensitivity, effect also achieved via resveratrol

• Brain: beneficial in degenerative diseases like Alzheimer’s, Parkinson’s, Huntington

Sirt1 as regulator for aging II

TÁMOP-4.1.2-08/1/A-2009-0011

• Deacetylates p53, inhibits apoptosis, promotes cell survival

• Deacetylates Foxo family members affecting DNA-damage repair, cell cycle arrest, apoptosis

• Deacetylates NF-kB, a prosurvival tanscription factor (context dependent)

Sirt1 and stress resistance

TÁMOP-4.1.2-08/1/A-2009-0011

• Several beneficial effects of CR effectuated through sirtuins

• CR induces eNOS and NO, upregulating Sirt1 and mitochondrial biogenesis

• Affects brain activity and indirectly physicial activity

Sirt1 and CR

TÁMOP-4.1.2-08/1/A-2009-0011

• Sirt2: cytoplasmic, tumor supressor gene• Sirt3: mitochondrial, thermogenesis in BAT• Sirt4: mitochondrial, response to amino acids• Sirt5: mitochondrial, high in thymus,

lymphoblasts• Sirt6: nuclear, DNA repair, genome stability• Sirt7: nucleolar, lacks enzymatic activity

Properties of other mammalian sirtuins

TÁMOP-4.1.2-08/1/A-2009-0011

• Changes in redox signaling may be more important than oxidative damage?

• Redox sensitive trsncription factors include NF-kB, Nrf2, HIF1

• Thioredoxin and glutathione systems modulate redox status

• Aging decreases GSH and thioredoxin levels

• CR increases GSH and thioredoxin levels

Redox signaling pathway

TÁMOP-4.1.2-08/1/A-2009-0011

• TOR (target of rapamycin), evolutionarily highly conserved, regulates cell growth

• Targeted deletions increase life-span• Daf-16 dependent, requires Foxo• Reduction (Ames dwarf mouse) leads to

decreased ROS production

TOR signaling pathway

TÁMOP-4.1.2-08/1/A-2009-0011

Resveratrol Treated Group

Untreated Group

Dose

Perc

ent S

urvi

vors

0 1 2 3 4 5 6

10

100

Resveratrol increases life-span

TÁMOP-4.1.2-08/1/A-2009-0011

• Currently few pharmacological Sirt1 mimetics are known: resveratrol, qercetin, piceatannol

• Natural source: red grapes / wine; cardio-protective, neuro-protective, cancer suppressing

• Can efficiently mimick certain CR-induced positive effects despite high-fat diet

Resveratrol

TÁMOP-4.1.2-08/1/A-2009-0011

CHEMOSENSITIVEAPOPTOSIS

Caspase-9

Caspase-3

Resveratrol

Paclitaxel

Caspase-7

Apoptosome

Resveratrol

Paclitaxel

Combined

Gene Expression

Cytc

Bid tBid

Smac/ Diablo

PARP

Bax

Bcl-xL

Mcl-1

Apaf-1

Survivin

C-IAP-1

XIAP

Mitochondria

Resveratrol / paclitaxel combination in cancer

TÁMOP-4.1.2-08/1/A-2009-0011

GH deficiencyor

GH resistance

Reducedhepatic

output ofIGF-1

Reduced sizeof islets and

secretionof insulin

Reduced metabolism and growthReduced ROS production

Enhanced liversensitivity to

insulin

Altered output of adiposetissue products reduces

insulin resistanceReduced abdominal fat?

IncreasedbrainIGF-1

Small size, late puberty,reduced reproduction, low insulin,

reduced body temperature and increased resistance to oxidative stress

Reduced oxidative damage

Delayedagingand

long life

Insulinresistance of

skeletal muscles

Primary effects of IGF-1Secondary effects

Primary effects of GH

Mechanism of action forGH / IGF pathway

TÁMOP-4.1.2-08/1/A-2009-0011

Environmental effects in expected life-span