Epigenetics III Flashcards
Non-Coding RNAs
do not code for protein
- short vs long (>200nts)
snoRNAs
small nucleolar RNA
- post-transcriptional modification *splicing
- encoded in introns
snRNAs
small nuclear RNA
- catalyze splicing of pre-mRNA (excise introns)
- associated with snRNPS in Cajal bodies
piRNA and exRNA
piwi-interacting RNA
- transposon silencing = stabilize genome
extracellular RNA
- cell communication
miRNA vs siRNA
miRNA
- single-stranded + bind to 3’UTR
- target hundreds of mRNA
- regulate genes other than ones that expressed them
- inhibit translation of mRNA
- therapeutic use
siRNA
- double stranded
- knock down specific genes
- regulate same genes that expressed them
- cleave mRNA (silence gene)
- laboratory tool to knock down
Pathway of miRNA and siRNA
- dsRNA or mRNA cleaved by DICER = siRNA/miRNA
- RISC targets complementary strand + rids passenger
- AGO recognizes mRNA
— 1-4 = miRNA
— 2 = siRNA - siRNA = complementary guide-target = mRNA cleave
- miRNA = non-complementary guide-target = repress translation
Long Non-Coding RNAs
- regulate expression of adjacent protein-coding genes
gene1 lncRNA gene 2 (prevent expression of 1+2) - Barr body = inactivate X chromosome