Cloning and characterization of two neural-salient serine/arginine-rich (NSSR) proteins involved in the regulation of alternative splicing in neurones.
BACKGROUND
In neurones, alternative splicing regulates the functions of many gene products. However, the molecular basis of neural-specific splicing, and how splicing regulation is modulated in different neurones remains to be determined.


RESULTS
We cloned two new SR proteins, Neural-salient SR proteins (NSSR) 1 and 2, which are present at higher levels in brain and testis. During the differentiation, NSSR 1 is detected only in the neuronal stage. Both the purified recombinant NSSR 1 and 2 proteins enhance the in vitro splicing activity of nuclear extract. Moreover, recombinant NSSR 1 protein enhances the assembly of ribonucleoprotein complexes with S100 fraction. Over-expression of NSSR 2 prevents the inclusion of either the Flip or Flop exons in the splicing of the GluR-B gene, resulting in an increase in the abnormal exon-skipping product. In contrast, transient transfection with NSSR 1 promotes the inclusion of the Flip exon so that the abnormal product is spliced to the mature spliced form. This suppression of exon skipping by NSSR 1 is observed even with co-transfection of NSSR 2.


CONCLUSIONS
NSSR 1 and 2 were cloned from mouse cDNA libraries. Results indicate that NSSR 1 may play a crucial role in the regulation of alternative splicing in neurones.
Komatsu
M
M
Department of Neuromuscular Research, National Institute of Neuroscience, NCNP, Ogawahigashi 4-1-1, Kodaira, Tokyo 187-8502, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan.
Kominami
E
E
Arahata
K
K
Tsukahara
T
T
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009928:Organ Specificity; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA / Q000378:metabolism; D012097:Repressor Proteins; D016415:Sequence Alignment; D014162:Transfection
D018797:Cell Cycle Proteins; C485446:Fusip1 protein, mouse; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA; D012097:Repressor Proteins; C115953:glutamate receptor type B