Lecture 10 Flashcards
(22 cards)
In the absence of the hormone, what keeps the glucocorticoid receptor in the cytosol?
Hsp90
Chaperone protein
What is the general role of chaperones?
Prevent inappropriate interactions
What happens when the glucocorticoid hormone enters the cell by diffusion?
It binds to the glucocorticoid receptor in the cytosol. Causes Hsp90 to dissociate by changing the shape of the receptor
What happens when Hsp90 dissociates?
The glucocortiosoid receptor moves into the nucleus as the nuclear localisation signal is now not masked by Hsp90
What happens in the nucleus with the glucocorticoid receptor?
The receptor binds to GRE in genes and activates transcription
How does the glucocorticoid bind to GRE?
As a dimer; one member of the dimer binds to each half sequence (GRE is an approximate palindrome)
What are steroid hormone receptors ? What protein?
Zinc finger proteins; zinc fingers are loops of amino acids stabilised by zinc ions
What is the role of AP1?
Increases general chromatin accessibility and helps glucocorticoid receptor bind to GRE
What do fibroblast cells normally form?
Extracellular matrix
What do fibroblast cells differentiate into and what causes them to?
Differentiate into muscle cells when the gene for and any of the 4 TFs is expressed in them
What are the 4 TFs that can reprogram fibroblast cell development?
MyoD, myogenin, Myf5, Mrf4
What does the process of normal formation of muscle cells start from?
Somites
What are somites?
Segmented paired blocks of cells that form on either side of the notochord.
In undifferentiated somite cells, signals from neighbouring cels induce transcription of genes for what?
MyoD and Myf5
What do MyoD and Myf5 do to somite cels>
Convert somite cells to undifferentiated muscle precursor cells called myoblasts
What would happen to mice that had myoD and myf5 genes knocked out?
They wouldn’t form myoblasts.
What gene is transcribed in myoblasts?
Myogenin
What does myogenin cause?
Causes myoblasts to fuse and form multinucleate mature muscle cells called myotubes
Which cells produce insulin?
Islet beta cells
Which transcription factors can reprogram exocrine cells of the pancreas to islet beta cells ?
Pdx1
Nhn3
MafA
What is ferritin?
Iron storage protein
What happens to ferritin when iron concentration is high?
The cell needs to store the pro so ferritin mRNA is translated
