Prezentacja programu PowerPointbiotka.mol.uj.edu.pl/zbm/handouts/2006_03_angiogeneza.pdf · 2009....
Transcript of Prezentacja programu PowerPointbiotka.mol.uj.edu.pl/zbm/handouts/2006_03_angiogeneza.pdf · 2009....
Hypoxia and hypoxia inducible factor-1- angiogenic and non-angiogenic functions
Lecture III
VEGFVEGF
Required for developmental angiogenesis
Ferrara et al.. Nature 1996Carmeliet et al., Nature 1996
Induced at pathologicalInduced at pathologicalconditionsconditions
Hypoxia
Inflammatory cytokines & growth factors
IL-1βTNFαIL-6
MCP-1GM-CSF
vascular endothelial growth factor
Regulation of Regulation of VEGF VEGF expression expression
1. Enhancement of VEGF mRNA expression
- activation of VEGF promoter - increased stability of VEGF mRNA
2. Enhanced translation through internal ribosome entry site (IRES)
Half-life of endogenous VEGF mRNA is about 65 minstability increases ~ 3 times in hypoxia
HuR – a member of Elav-like family of binding proteins; binds todistal AU-rich region in the VEGF 3’UTR. Stabilizes VEGF mRNA
Hypoxia Hypoxia –– one one of the strongest inducers of of the strongest inducers of VEGF VEGF expression expression
Tumor growth is dependent on angiogensis
Hypoxic area is formed inside growing tumor Hypoxic area is formed inside growing tumor
Hypoxic areas in bone marrow – EPCs home to this side
Ceradini et al., Nature Med. 2004
Pimonidazole - green
SDF-1 – red
DAPIBM – bone marrowC – cortical bone P – non-ischemicperiosteal tissue
Causes of tissue hypoxia Causes of tissue hypoxia
1. Decrease in blood oxygenation (pulmonary disorders) 2. Altered oxygen release from hemoglobin3. Impaired blood delivery (ischemia) – cardiovascular diseases
Coronary artery diseasePeripheral vascular disease
Impaired blood flow, hypoxic simulation of angiogenic factors,
JAMA & Archives Journals
Currents: Fall 2001
Ischemia in cardiovascular diseasesIschemia in cardiovascular diseases
What is hypoxiaWhat is hypoxia??
Atomospheric 21% O2
Lung capillaries 13% O2
Healthy tissues 2.5-9% O2
Diseased tissue < 1% O2
Protective physiological mechanisms against hypoxia Protective physiological mechanisms against hypoxia
1. Increased production of tyrosine hydroxylase – controls the ventilation through the carotid body
2. Increased expression of glycolytic enzymes 3. Increased synthesis of erytropoietin 4. Increased production of VEGF – stimulation of new blood
vessels
How do cells sense the changes in the oxygen level?
Acker, T. et al. J Exp Biol 2004;207:3171-3188
Dual role of HIF in regulating cell survival and cell death, depending on
The studies of hypoxia response element of the erythropoietin gene lead to the discovery of HIF-1 by
Semenza and Wang in 1992. Semenza GL & Wang GL. (1992). Mol. Cell. Biol. 12: 5447-5454.
HIFHIF--1: 1: HHypoxia ypoxia IInducible nducible FFactor actor -- 11
HIF-1 is a protein with DNA binding activity. It is composed of two subunits: HIF-1α and HIF-1β.
Hammond Hammond et al., et al., Mol Mol Cell Biol Cell Biol 20022002
Stabilisation of Stabilisation of HIFHIF--11αα proteinprotein in hypoxia in hypoxia
HypoxiaHypoxia inducibleinducible factorfactor ––a master regulator a master regulator of oxygen homeostasis of oxygen homeostasis
HIF
Erythropoiesis & iron metabolismErythropoietinTransferrinTransferrin receptorCeruloplasminHeme oxygenase-1 (rodents)
Vasomotor controlNOS II
Cell proliferation & viability IGF-1IGFBP-1&3TGFβ3NOS II
Energy metabolismGLUT1,2 & 3PEPCKLDH APGK3Aldolase A & C PFK L & C Pyruvate kinaseEnolase
AngiogenesisVEGFVEGFR-1PlGFPDGFTGFβ
O2
Structure of Structure of VEGF VEGF human promoter human promoter
HIFHIF--1 1 binds binds to to hypoxia responsive hypoxia responsive element element present in regulating present in regulating regions of many genesregions of many genes
Zagórska & Dulak Acta Biochim Pol 2004
Various HRE
Mole et al., IUBM, 2001
Activation and degradation of Activation and degradation of HIFHIF--11αα
HIF-1β &
- Both α and β subunits are members of basic helix/loop/helix (Per/Arnt/Sim) (PAS) family
- there are three HIFα family members: HIF-1α, HIF-2α, HIF-3αand three HIFβ members: HIF-1β/ARNT1, HIF-2β/ARNT2, HIF-3β/ARNT3,
- IPAS3, a HIF-3α isoform, can act as inhibitor of HIF
- HIF-α members exclusively dimerize with HIF-β members, while the oppositeis not true
- over 100 HIF-dependent genes
- canonical HIF binding site: 5’-RCGTG
MoreMore on HIF on HIF transcription factorstranscription factors
HIF-1 transcription factors
HIF-1α – knockouts die at E 9.0
HIF-2α – expressed in fetal type 2 pneumocytes
- knockouts die in utero – adrenal insufficiency
Activation and degradation of Activation and degradation of HIFHIF--11αα
Zagórska & Dulak, Acta Biochimica Polonica, 2004
Prolyl hydroxylases are ironProlyl hydroxylases are iron--dependent dependent dioxygenasesdioxygenasesinvolved ininvolved in HIFHIF--11αα degradation degradation
PHD1 PHD1 –– hydroxylateshydroxylates P 402 & P564P 402 & P564
PHD2 PHD2 -- hydroxylateshydroxylates P 402 & P564 P 402 & P564
PHD3 PHD3 -- hydroxylateshydroxylates P564 P564
Asparaginyl hydroxylase Asparaginyl hydroxylase (FIH)(FIH) modifiesmodifies HIFHIF--11αα and prevents binding and prevents binding ofof p300 cop300 co--activator activator
CoCo--factors of PHDsfactors of PHDs: : ironiron, , oxygenoxygen, 2, 2--oxoglutarate oxoglutarate , , ascorbic acidascorbic acid
Hypoxia enhances Hypoxia enhances VEGF VEGF expression and activity in several ways expression and activity in several ways
IRES A is located within the 300 nucleotides upstream from the AUG start codon. RNA secondary structure prediction and site-directed mutagenesis allowed the identification of a 49-nucleotide structural domain (D4) essential to IRES A activity. UV cross-linking experiments revealed that IRES A activity was correlated with binding of a 100-kDa protein to the D4 domain. IRES B is located in the first half of the 5' UTR. An element between nucleotides 379 and 483 is required for its activity.Immunoprecipitation experiments demonstrated that a main IRES B-bound protein was the polypyrimidine tract binding protein (PTB), a well-known regulator of picornavirus IRESs
VEGF VEGF mRNA has two mRNA has two IRESIRESHuez I et al., Mol Cell Biol, 1998
IRES IRES initiates translation initiates translation independent independent of of capcap
Hypoxia Hypoxia upup--regulatesregulates VEGF VEGF expressionexpressionin in humanhuman microvascular microvascular endothelialendothelial cellscells
(HMEC(HMEC--1)1)
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EF2EF2
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VEGF promoter luciferase
HRE
HRE luciferase
Activation of Activation of VEGF VEGF promoter and promoter and HRE HRE part part by by hypoxia hypoxia
Regulation of Regulation of VEGF VEGF expression expression by by hypoxia is cellhypoxia is cell--type type dependent dependent
hypoxianormoxia
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VEGF mRNA expressionVEGF protein
NIH 3T3 NIH 3T3 fibroblastsfibroblasts
HMECHMEC--11
Łoboda A et al., in preparation
How to modulate HIFHow to modulate HIF--1 activity?1 activity?
• Hypoxia • Iron chelators: desferrioxamine, CoCL2
• Dominant positive/negative forms, siRNA, oligonucleotide decoys
• Chemical compounds: DMOG (dimethyloxallyl glycine)
Other mechanisms of stabilisation of Other mechanisms of stabilisation of HIFHIF--1 1
1. Iron chelators – eg. desferroxiamine effect was reversed by ferrous amonium sulfate
- induction of VEGF synthesis by desferroxiamine
2. Heavy metal – cobalt chloride
CoClCoCl2 2 is known is known to to potently activate potently activate HIFHIF--11
Increase in HIF- protein levels by cobalt stimulation in osteoblast-like cells.
Kim at al.,Cytokine. 2002 Jan 7;17(1):14-27.
CoClCoCl22 activates activates VEGF VEGF promoter in its promoter in its HRE HRE site site
VEGF promoter luciferase
HRE
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DMOG (Dimethyloxallyl glycine)
• Competitive inhibitor of the oxygen-sensing enzymes - prolyl hydroxylases (PHDs), which destruct HIF-1 α when hydroxylated at a specific proline residues.
• Stabilizes HIF-1 α expression at normal oxygen tensions at concentrations between 0.1 and 1 mM
DimethyloxallylDimethyloxallyl glycineglycine (DMOG)(DMOG)
HIFHIF--11 hydroxylationhydroxylation andand actionaction ofofDMOGDMOG
HIFHIF--11αα HIFHIF--11αα
22--OXOGLUTARATEOXOGLUTARATE
OO22 COCO22
PROLYL HYDROXYLASESPROLYL HYDROXYLASES
OH OHOH OHpVHLpVHL
FeFe2+2+
SUCCINATESUCCINATE
NORMOXIANORMOXIAHYPOXIAHYPOXIA
proteasomalproteasomaldegradationdegradation
stabilizationstabilization
e.g. VEGFe.g. VEGF
• Potent VEGF stimulation both at mRNA and protein level
Effect of HIF-1 activation on VEGF synthesis in HMEC-1
EF 2EF 2
VEGFVEGF
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Diseases caused by disturbances in HIF-1 signaling
-von Hippel Lindau disease
Diseases dependent on enhanced HIF-1 activity- cancer
- atherosclerosis
-wound healing
VHL protein VHL protein
Von Hippel Lindau protein
Von Von Hippel Lindau disease Hippel Lindau disease
Hemangioblastoma of the retina
Brigham and Women’s Hospital, Boston
-rare (1:36 000 live births) dominantly inherited cancer syndrome
- multiple hemangioblastomas of CNS and retina, renal cell carcinomaspancreatic islet cell tumors and others
Desrcibed in 1911 by Eugene von Hippel and further studied in 1926 by Arvid Lindau
Defect in Defect in VHL VHL tumor suppresor gene tumor suppresor gene in chromosome in chromosome 3p253p25--p26p26
Mutations in VHL occur also in the majority of kidney cancers
Is it not known which HIF-1αresidues are ubiquitinated
Mutation in VHL gene causes disruption in HIF-1 degradation process
Nature Genetics, 2001: 28: 131-138
Generation of VEGFGeneration of VEGFδδ/δ/δ micemice
Deletion of Deletion of HRE region HRE region of of VEGF VEGF promoter causes promoter causes ALS ALS in in mice mice
-Cre/Lox deletion of HRE – VEGFδ/δ
- reduced hypoxic expression of VEGF in neural tissues, but not in cultured fibroblast
- no changes in other gene
real-time RT-PCR analysis
TissueTissue--specific regulation of specific regulation of VEGF VEGF expression in hypoxia expression in hypoxia
Muscle weakness in VEGFMuscle weakness in VEGFδδ/δ/δ micemice
Oosthuyse et al., Nature Genetics, 28: 131-138, 2001
atrophic muscles
-~ 60% VEGFVEGFδδ/δ /δ died beforedied before or around birth or around birth - remaining – at around 5 months of age developed symptoms of motor neuron disease
Impaired motor performance
Muscle and neuronal atrophy in VEGFMuscle and neuronal atrophy in VEGFδδ/δ/δ micemice
Axonal spheroid swelling
- muscle atrophy - motor neuron degeneration - axon degeneration - abnormal neural vascular perfusion – reduced blood flow
in the spinal cord
Vacuolized mitochondria
Which human disease does this mouse Which human disease does this mouse model model resembleresemble? ?
Amyotrophic lateral sclerosisAmyotrophic lateral sclerosis –– Lou Gehring diseaseLou Gehring disease
Spinal cord – the atrophy is apparent in ALS
Amyotrophic lateral sclerosis Amyotrophic lateral sclerosis
AmyotrophicAmyotrophic lateral sclerosis lateral sclerosis (ALS) (1) (ALS) (1)
1869 – Jean Martin Charcot
Famous patients:
-Lou Gehring- Dimitir Shostakovich - Mao Zedong (infamous patient...) - Stephen Hawking – suffers from unusually slowly progressing
form of a disease
1903-19411942 –
Diagnosed at age of 21
Famous Famous AML AML patientspatientsLou Gehring Stephen Hawking
AmyotrophicAmyotrophic lateral sclerosis lateral sclerosis (ALS) (1) (ALS) (1)
Incidence – 2-3:100 000
Onset at 50-60 years
Sporadic (SALS) – most instances (90-95%)Familial (FALS) – 5-10% - of these 20-25% are mapped to CuZnSOD
gene
Degeneration of motor neurons – progressive loss of the ability to move, speak,
Usually fatal within 1-5 years of onset
No treatment available
Amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS) (3)(ALS) (3)90-95 % of cases – no apparent genetic linkage 5-10 % - familial ALS – mutation in SOD1 gene are responsible
for 10-20 % of cases of FALS
-about 100 different mutations in SOD1 gene
-mutations do not cause the lost of functions, but rather gaining of a toxic phenotype
-among others, the formation of hydroxyl radicals and peroxy-nitrite has been suggested
Yuan J & Yankner BA, Nature 407, 802 - 809 (2000)
SOD1 and AML
How does How does VEGF VEGF protect nervesprotect nerves??
Neurotrophic functions of VEGF
Oosthuyse et al., Nature Genetics, 28: 131-138, 2001
VEGF165 (but not VEGF121) prevents neuronal apoptosis
survival effect of VEGF165 is blocked by antibodies against Kdr and Nrp
Neuroprotective functions of Neuroprotective functions of VEGF VEGF
Oosthuyse et al., Nature Genetics, 28: 131-138, 2001
Storkebaum E & Carmeliet P, JCI 2004
Both Kdr and Nrp-1 are required
Neuroprotective functions of Neuroprotective functions of VEGF VEGF
Neuroprotective functions of Neuroprotective functions of VEGF VEGF –– other other data data - increased axonal outgrowth and cell survival in peripheral neuronal culture
- protects immortalized hippocampal cell culture from serumwithdrawal and hypoxia in vitro – mediated by VEGFR2, PI3K, Akt, NF-kB
- reduced hypoxic death of cultured cereberal cortical neurons –due to activation of VEGR2, PI3K, decrease in caspase 3
- protects hippocampal neurons from glutamate toxicity
- Stimulate the birth of new neurons (neurogenesis)
- Neuroprotective at in vivo ischemia
Questions created Questions created by by seminal paper of Oosthuyse seminal paper of Oosthuyse et al. et al.
- what is the level of VEGF in patients with ALS? – search for VEGF gene polymorphism
- if SOD1 mutation causes the neuronal damage, what will be the result of a combined effect of SOD1 mutation and VEGFδ/δ ?
- will VEGF prevent ALS development?
Single nucleotide polymorphisms or SNPs (pronounced "snips") areDNA sequence variations that occur when a single nucleotide (A,T,C,orG) in the genome sequence is altered. For example a SNP might change the DNA sequence AAGGCTAA to ATGGCTAA. For a variation to beconsidered a SNP, it must occur in at least 1% of the population. SNPs,which make up about 90% of all human genetic variation, occur every100 to 300 bases along the 3-billion-base human genome. Two of every three SNPs involve the replacement of cytosine (C) with thymine (T).SNPs can occur in both coding (gene) and noncoding regions of the genome. Many SNPs have no effect on cell function, but scientists believe others could predispose people to disease or influence their response to a drug.
Single Single nucleotide polymorphisms and diseasesnucleotide polymorphisms and diseases
A common polymorphism in 5’UTR of VEGF gene is associated with diabetic retinopathy in type 2 diabetes
Awata T et al., Diabetes, 51: 1635-1639, 2002
Proliferative diabetic retinopathy
Hemorrhages in non-proliferative diabetic retinopathy
New blood vessels around optic nerve in proliferative diabetic retinopathy
Hemorrhage from new blood vessel growth in proliferative diabetic retinopathy
Normal macula
Polymorphism in 5’UTR changes the structure of mRNA
VEGF VEGF promoter polymorphism and promoter polymorphism and ALS ALS
-no sequence alterations in HRE in individuals with ALS
-three VEGF promoter and 5’UTR polymorphism and ALS
VEGF plasma level was the lowest in ALS patient with AAG/AAG and AGG/AGG haplotypes
Correlation of Correlation of median serum VEGF median serum VEGF values with the different values with the different genotypes in Belgian control population genotypes in Belgian control population
Effect of combined mutation in Effect of combined mutation in SOD SOD and and VEGFVEGF
Shorter survival of Shorter survival of SOD1SOD1G93A G93A VEGFVEGFdd/d/d mice mice relative relative to SOD1to SOD1G93A G93A VEGFVEGF+/++/+
score 1 score 4Unable to walkLimbs immobile when lifted by tail
Administration of VEGF improves motor recovery after acute spinal cord ischemia
PGF was not effective
Gene therapy with Gene therapy with VEGF VEGF can prolong survival in can prolong survival in a a mouse mouse model model of of ALSALS
Azzouz et al, Nature 27 May 2004
single injection of VEGF-expressing lentiviral vector into various muscles delayed onset and slowed progression of of ALS in mice engineered to overexpress the G93A mutated form of SOD1, even when treatment was only initiated at the onset of paralysis
Survival of Survival of mice mice injected at three weeks of age and at injected at three weeks of age and at 90 90 days of agedays of age
Multitasking Multitasking VEGFVEGF
Velde & Cleveland, Nature Neuroscience 2005