Block 3 Lecture 4 -- Regulation of Gene Expression Flashcards
What is euchromatin?
loosely packed DNA, active transcription present
What is heterochromatin?
tightly packed DNA
How long is miRNA?
19-21 bases
What are the effects of miRNA binding to mRNA?
translational repression or mRNA cleavage
What is epigenetics?
heritable information encoded by modifications of the genome and chromatin affecting gene expression
Acetylation’s effect on this histone:
acetylated = activated
In what cancers is HAT/HDAC altered?
epithelial tumors
leukemia
HAT:
histone acetyltransferase
HDAC:
histone deacetylase
DNMT:
DNA methyltransferase
What is methylation’s effect on transcription?
repression
Where is DNA methylated?
CpG island (Cs and Gs in promoter)
MoA of vorinostat:
inhibits HDAC to induce growth arrest proteins
– ex p21
MoA of 5-azaC:
5’ modified dCTP analog that covalently inhibits DNMT
– produces DNA instability
What are the limitations to vorinostat use?
1) can’t tell if HDAC is overexpressed
2) HAT has to work for effect
Estrogen Receptor commonly not expressed in ovarian cancer. Why?
hypermethylation of promoter
What mechanisms are involved in epigenetics?
1) histone acetylation
2) DNA methylation
What things regulate gene transcription?
1) eu/heterochromatin modifications
2) DNA modifications
3) DNA sequence
4) miRNA regulation
What are steroid transcription factor examples and where are they located?
retinoic acid receptor, TH receptor
– cytosol
What are the domains of the TH and retinoic acid receptor?
DNA and ligand-binding
How do steroid transcription factors regulate transcription?
1) bind ligand
2) dimerize, translocate
3) bind DNA
