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7SK snRNA: a noncoding RNA that plays a major role in regulating eukaryotic transcription
Journal article   Open access   Peer reviewed

7SK snRNA: a noncoding RNA that plays a major role in regulating eukaryotic transcription

B. Matija Peterlin, John E Brogie and David H Price
Wiley interdisciplinary reviews. RNA, Vol.3(1), pp.92-103
01/2012
DOI: 10.1002/wrna.106
PMCID: PMC3223291
PMID: 21853533
url
https://doi.org/10.1002/wrna.106View
Published (Version of record) Open Access

Abstract

The human 7SK small nuclear RNA (snRNA) is an abundant noncoding RNA whose function has been conserved in evolution from invertebrates to humans. It is transcribed by RNA polymerase III (RNAPIII) and is located in the nucleus. Together with associated cellular proteins, 7SK snRNA regulates the activity of the positive transcription elongation factor, P-TEFb. In humans, this regulation is accomplished by the recruitment of P-TEFb by the 7SK snRNA-binding proteins, HEXIM1 or HEXIM2, which inhibit the kinase activity of P-TEFb. P-TEFb regulates the transition of promoter proximally paused RNA polymerase II (RNAPII) into productive elongation, thereby, allowing efficient mRNA production. The protein composition of the 7SK small nuclear ribonucleoprotein (snRNP) is regulated dynamically. Whereas the La related protein LARP7 is a constitutive component, the methyl phosphate capping enzyme MePCE associates secondarily to phosphorylate the 5' end of 7SK snRNA. The release of active P-TEFb is closely followed by release of HEXIM proteins and both are replaced by heterogeneous nuclear ribonucleoproteins (hnRNPs). The released P-TEFb activates the expression of most cellular and viral genes. Regulated release of P-TEFb determines the expression pattern of many of the genes that respond to environmental stimuli and regulate growth, proliferation and differentiation of cells.

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