HIF Pathway Flashcards

1
Q

In which situations does the hif pathway get activated

A

Hypoxic environments Eg altitudes

Hif is hypoxia indictable factor

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2
Q

What can happen to cells in hyperoxia

A

Oxidative stress

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3
Q

Why is hypoxia relevant to cancer and what does hif and nfkb do

A

Cancer tumours become hypoxic because no vessels

Hif and nfkb promote angiogenesis

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4
Q

Name ways cells can react to hypoxia to restore survival or induce death

A

Dna replication blocked

Translation blocked to conserve energy

Transcriptional changes

Chromatin change

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5
Q

What makes up a hif dimer

A

Hif 1a and hif 1b

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6
Q

How is hif 1a different to hif 2a

A

Hif 1a is expressed in all tissues

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7
Q

How is hif 3a different

A

Lacks c terminal activation domain CTAD and nuclear localisation signal

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8
Q

Is hif 1a regulated or hif 1b

A

Hif 1a

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9
Q

Which dna binding domain does Hif have

A

Basic HLH helix loop helix

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10
Q

Which domain is important for HIF1a/2a degradation in presence of oxygen

A

ODD oxygen dependant domain

N terminal domain

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11
Q

What does hif 1b not have

A

ODD/NTAD
NLS
CTAD

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12
Q

What gets hydroxylated on the ODD of hif1a

A

Proline

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13
Q

What gets hydroxylsted on the CTAD of Hif 1a which inhibits the transactivated domain via FIH

A

Asparagine

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14
Q

During high oxygen levels what keeps hif being degraded and how

A

Phd

They hydroxylate the proline on the ODD

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15
Q

What does hydroxylation of proline on ODD of Hif 1a do

A

Attracts protein called VHL which causes ubiquitination of hif1a

Then degraded by proteasome

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16
Q

When in hypoxic conditions what happens to hif 1a

A

Phd can’t hydroxylase proline on the odd which means VHL isn’t attracted and ubiquitination can’t occur so hif1a stays active

17
Q

When is FIH active to inactivate the CTAD via asparagine hydroxylstion

A

When o2 is present

18
Q

Which part of the hif1a hif1b heterodimer binds to coactivators like p300/cbp HAT to regulate gene expression

A

CTAD on hif1a

19
Q

What types of genes does hif target in hypoxia

A

Erythropoietin to increase RBC Carry of oxygen

20
Q

Other than hypoxic gene responses what other genes does hif dimer regulate with coactivator p300/cbp

A

Metabolism
Cell death
Cell growth