Lecture 10 Post-transcriptional Regulation Gene Expression

eukaryotic gene expression being regulated at multiple levels slide

alternative splicing slide

gene expression can be regulated through RNA —-

stability and degradation

alternative splicing drosophila slide

_ are constantly trying to destroy mRNA, especially —

enzymes that are highly regulated are constantly trying to destroy mRNA especially in the cytosol

some of these enzymes cause complete destruction while others

are just removing some markers such as the poly-A-tail or the 5’ cap

regulation through RAN stability and degradation slide

some proteins need to be expressed for only

a specific amount of time

ubiquitin can used in so many ways other than just

destruction

ubiquitin destruction pathway

_ target specific mRNAs for destruction

small RNAs

the endogenous “—“ called —- is process to form a mature miRNA

“noncoding RNA“ called precursor microRNA (miRNA)

miRNA assemble with

a set of proteins into RNA induced silencing complex (RISC)

miRNA guides RISC to

mRNAs that have a complementary nucleotide sequence

RNA interference is what type of regulation of gene expression

post transcriptional

RNA interference slide

what are siRNAS

derived from long double-stranded RNA molecules (viral infection or the expression of transposons may synthesize dsRNA, Lab derived)

RNAi may have evolved as a mechanism to ___

recognize these dsRNAs and inactivate them, protecting the cell from external (viral) or internal (transposon) assaults.

when dsRNAs are present in cytoplasm they are

cleaved into around 22-nt long siRNAs by an enzyme called dicer

siRNAs associate with

RISC

RISC contains

argonaute family protein, binds RNA and has endoribonucleases or slicer activity

RISC does what to a strand of siRNA

cleaves and evicts it, retains other strand as siRNA “guide“ to recruit RISC to complementary mRNA

RISC cleaves the mRNA where

in the middle of the region of the siRNA-mRNA complementarity

genes for miRNAs represent what percentage of the human genome

around 4%

which represents a greater percentage of the human genome protein coding genes or miRNA coding genes

miRNA coding genes

a miRNA may affect the regulation of up to

400 target genes

expression of at least _% of all human protein encoding genes is regulated in part by miRNAs

60

miRNAs in everyday life slide

therapies with RNAi slide

daphnia are

water fleas

Long Noncoding RNAs are also called

LINK

LINK can influence

gene expression

Long noncoding RNAs are often processed like

mRNAs

long noncoding RNAs are linked to divers regulatory functions such as

influence condensation, associating with TFs, post-transcriptional regulation, and miRNA sequestration

long noncoding RNAs slide