Non-coding lncRNAs 1 Flashcards
What are ncRNAs?
Non-coding RNAs
Not translated into protein (functional RNA = end product)
What are the 2 main classes of ncRNAs?
Housekeeping
Regulatory (gene regulation)
Name 3 housekeeping ncRNAs
rRNA
tRNA
snRNA
Name 4 regulatory specific ncRNAs
miRNA (micro)
siRNA (small interfering)
piRNA (Piwi interacting)
lncRNA (Long non-coding)
When was protein coding mRNA discovered?
1961
When was the 1st lncRNA (H19) discovered?
1989
What transcribes ncRNAs?
RNA polymerase II (same as protein coding RNAs)
What length are lncRNAs?
> 200 nucleotides
Do lncRNAs a polyA tail + 5’ 7-methylguanosine cap?
Yes
Name the different classes of lncRNAs
Sense overlapping transcript Intergenic Intronic Bidirectional Antisense transcript 3' UTR associated transcript
What are intergenic lncRNAs?
Don’t overlap protein coding genes
Have their own promoter
Associated w/ transcriptional control
What are the differences bet. protein coding genes + non-protein coding lncRNA genes?
lncRNAs have: = shorter transcript length = fewer no. of exons = less expressed = much more tissue specific expression
What is the advantage of lncRNAs being tissue specific?
Can be drug targets w/ minimal side effects
lncRNAs have functions in development + differentiation.
Name 2 examples
Xist = silencing of 1 X chromosome
line-MD1 = muscle differentiation
What is the most common type of variation of DNA bet. cancer patients + controls?
Single-nucleotide polymorphisms (SNPs)
How were SNPs in DNA associated with cancer?
GWAS (Genome-wide association studies)
Where are the majority of cancer associated SNPs found?
Within lncRNA loci
What types of DNA changes are associated w/ cancer?
Single-nucleotide polymorphisms (SNPs)
Somatic copy-number alterations (SCNAs)
Amplification + deletion of lncRNAs
What are focal SCNAs?
Somatic copy-number alterations that cover 1 or 2 genes
Amplified or deleted lncRNAs are mostly found where?
Short focal alteration regions that contain no known cancer-associated protein-coding genes
-> may play a role in cancer
Different cancers show different patterns in lncRNA expression
lncRNAs = expressed in tumour specific manner
lncRNA expression signatures can be used to distinguish cancer cells from normal cells
What % of cancer associated SNPs are located in the non-coding portion of the genome?
> 80%
LncRNAs expression in cancers: which one of these statements is wrong?
(A) A large number of lncRNAs are expressed in most cancers
(B) Cancers show specific patterns of lncRNA expression
(C) lncRNAs show similar patterns of expression in cancerous and normal tissue
C
What is HOTAIR lncRNA?
Acts as an oncogene
Promotes breast cancer metastasis
Powerful prognostic marker (high expression -> lower survival)
What is H19 lncRNA?
Acts as tumour suppressor
Normal function = gene imprinting
Maternally expressed
Inactivation in cancer by promoter hypermethylation
