Gene expression and regulation - Lecture 8

How is transcription regulated

via molecules involved in RNA synthesis (aka transcription)

molecules involved in RNA synthesis

bindings of transcription factors

presence of lipid-derived hormones

histone or DNA modification

lipid derived hormones

diffuse across plasma and organelle membrane (often hydrophobic)

lipid derived hormones - nuclear hormone receptors

recognized by _______ _______ receptors bound to DNA

lipid derived hormones - receptor site

these generally far away from transcription start site, but once activated (by hormone binding) they recruit proteins that modify histones

lipid derived hormones - recruited proteins that modify histones

may promote or hinder gene expression via chromatin remodeling

lipid derived hormones - mRNA stability

steroid hormones also impact this

steroid hormones impacting mRNA stability

estrogen for example, induces E-RmRNASE

this protein binds to particular mRNAs, preventing degradation

Modifications that promote gene expression

these modifications promote chromatin remodeling (from condensed state to open/accessible state)

Modifications that promote gene expression - acetylation

___________ of histone amino-terminal tail reduces affinity with nucleic acid

Modifications that promote gene expression - phosphorylation

Histone ______________ also reduces affinity with nucleic acid, as modification promotes acetylation

Modifications that hinder gene expression

these modifications promote chromatin remodeling (from condensed state to open/accessible state)

Modifications that hinder gene expression - Ubiquitination

______________ of histone amino-terminal tail associated with gene silencing, but the mechanism is unclear

Modifications that hinder gene expression - DNA methylation

DNA ___________ causes nucleosome beads to pack more tightly together

associated with epigenetic; DNA sequence not altered

epigenetic

heritable changes in gene expression due to environmental factors