ANHB3323 Lecture Notes - Lecture 5: Metastasis, Adenocarcinoma Of The Lung, Xist (Gene)
3 Jun 2018
School
Course
Professor
LECTURE FIVE: Non-Coding RNA
Regulatory RNA:
• Proteins are not the only regulatory molecules in cell biology
• RNA does not need to be translated to encode regulatory function
• RNA can work through mRNA recognition while also acting as a scaffold
for complexes of proteins
• Key forms of regulatory RNAs
o miRNAs → natural in genome
o Long non-coding RNAs → natural in genome
o Long dsRNA → pathological/viral genomes
o siRNA → synthetic/synthesized by companies, development
derived from development of miRNA
• RNA is adaptable → not tied to a chromosome like DNA or an end-point
like proteins
• Proportion of non-coding DNA increases with the complexity of an
organism → humans have the most non-coding DNA
Micro RNA (miRNA):
• Small non-protein coding RNAs
• 21-22 nucleotides long
• Double stranded
• Found in almost all plants and animals
• Genes for miRNAs are found throughout genome → often in introns or
intergenic
• Predicted to be approximately 1000 miRNA genes in humans
miRNA Function:
• Post-transcriptional gene regulators
• Recognize targets in 3 un-translated region (UTR) of mRNAs by sequence
specific binding
• If the match is perfect → degrade mRNA target
• If match is not perfect → inhibit translation (i.e. making protein)
• Can regulate gene networks to control diverse biological processes
• miRNA can have multiple target mRNAs → some being degraded, others
translationally inhibited
• Most miRNAs imperfectly match their targets → allow reversible fine-
tuning of gene expression
Case Studies:
• Mir7 → tumor suppressor miRNA
o Down-regulated in cancer
o Targets central oncogenic factors in cancer-associated signaling
pathways
o Plays a role in preventing invasion and migration in melanoma
o Melanoma cells express less mir7 than control
o The melanoma cell lines cannot migrate well when mir7 is
overexpressed
find more resources at oneclass.com
find more resources at oneclass.com
