Gene Regulation and RNA Interference

Flashcards covering key concepts related to gene regulation, RNA interference, and the roles of Dicer, RISC, siRNA, and miRNA.

What is Dicer?

The siRNA producing double-stranded endoribonuclease.

How does Dicer work?

It binds and cleaves as a dimer, processing dsRNA into ~22n+ ds-siRNA.

What is RISC?

Silencing complex activated by ATP-dependent unwinding of ds-siRNA.

What is Ago2?

A protein in the RISC that degrades ss-siRNA mRNA.

What is siRNA?

Small interfering RNA that can induce RNA interference.

Why don't long dsRNAs lead to RNAi in mammalian cells?

They trigger the anti-viral response leading to degradation by RNase L.

What is the difference in the production of siRNA and miRNA?

siRNA is produced exogenously by Dicer with a perfectly complementary antisense strand. miRNA is transcribed from the genome and processed from hairpin precursors.

What are the differences between the miRNA gene silencing pathways?

Imperfect pairing with 3'UTR leads to translation block; mRNA cleavage occurs with perfect pairing.

What are miRNAs?

MicroRNAs, 18-25n+ RNAs produced in plants and animals by cleavage from 75nt stem-loop precursor RNA.

How does miRNA work in gene silencing?

Single strand (ss) miRNA pairs with mRNA for gene silencing.

How is miRNA processed?

In the nucleus, pri-miRNA is reduced by Drosha to pre-miRNA, then processed by Dicer to form a miRNA duplex.

What is the role of miRNAs in humans?

They are involved in cancer development, cardiac development, muscle disorders, hematopoiesis, immune response, and neurological diseases.

What is the role of miRNAs in tumor suppressor genes?

Gene amplification of miRNAs negatively regulates tumor suppressor genes, leading to tumor formation.

What is the role of miRNAs in oncogenes?

Gene deletion/mutation leads to overexpression of oncogenes; miRNAs may serve as cancer biomarkers.

What is the role of miRNAs in heart disease?

MiRNAs are involved in cardiac fibrosis.

What is the role of miRNAs in the immune system?

MiRNAs play key roles in the innate immune cell development and B cell and T cell function.

What happens in miRNA processing in the cytoplasm?

Drosha processes pri-miRNA to pre-miRNA, then Dicer produces miRNA duplex.

What is the length range of miRNAs produced?

MiRNAs are typically 18-25 nucleotides long.

What type of RNA structure do miRNAs originate from?

MiRNAs are derived from 75nt stem-loop precursor RNA.

How do miRNAs affect translation?

They can cause translation blocks through imperfect pairing with mRNA.