Nucleic Acids Research, Vol 27, Issue 23 4577-4584, Copyright © 1999 by Oxford University Press
TA Gray, MJ Smithwick, MA Schaldach, DL Martone, JA Graves, JR McCarrey and RD Nicholls
The human small nuclear ribonucleoprotein SNRPB ' /B gene is alternatively
spliced to produce the SmB or SmB' spliceosomal core proteins. An ancestral
duplication gave rise to the closely related SNRPN paralog whose protein
product, SmN, replaces SmB'/B in brain. However, the precise evolutionary
and functional relationship between these loci has not been clear. Genomic,
cDNA and protein analyses presented here in chicken, two marsupials (South
American opossum and tammar wallaby), and hedgehog, suggest that the
vertebrate ancestral locus produced the SmB' isoform. Interestingly, three
eutherians exhibit radically distinct splice choice expression profiles,
producing either exclusively SmB in mouse, both SmB and SmB' in human, or
exclusively SmB' in hedgehog. The human SNRPB ' /B locus is biallelically
unmethylated, unlike the imprinted SNRPN locus which is unmethyl-ated only
on the expressed paternal allele. Western analysis demonstrates that a
compensatory feedback loop dramatically upregulates SmB'/B levels in
response to the loss of SmN in Prader-Willi syndrome brain tissue,
potentially reducing the phenotypic severity of this syndrome. These
findings imply that these two genes encoding small nuclear
ribonucleoprotein components are subject to dosage compensation. Therefore,
a more global regulatory network may govern the maintenance of
stoichiometric levels of spliceosomal components and may constrain their
evolution.
ARTICLES
Concerted regulation and molecular evolution of the duplicated SNRPB'/B and SNRPN loci
Department of Genetics, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, 10900 Euclid Avenue, Cleveland, OH 44106-4955, USA,
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
S. B. Patel and M. Bellini The assembly of a spliceosomal small nuclear ribonucleoprotein particle Nucleic Acids Res., November 1, 2008; 36(20): 6482 - 6493. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. G. Scofield and M. Lynch Evolutionary Diversification of the Sm Family of RNA-Associated Proteins Mol. Biol. Evol., November 1, 2008; 25(11): 2255 - 2267. [Abstract] [Full Text] [PDF] |
||||

