Isolation of cDNA clones encoding small nuclear ribonucleoparticle-associated proteins with different tissue...

Area of Science:

• Molecular Biology
• Genetics
• Neuroscience

Background:

• Alternative RNA processing generates tissue-specific transcripts like calcitonin gene-related peptide (CGRP).
• Tissue-specific factors are believed to mediate these differential RNA processing events.

Purpose of the Study:

• To identify and characterize novel small nuclear ribonucleoparticle (snRNP)-associated proteins involved in tissue-specific RNA processing.
• To investigate the expression patterns of these proteins in different rat tissues.

Main Methods:

• Cloning of three distinct cDNAs (Sm51, Sm11, Sm21) encoding snRNP-associated proteins from rat PC12 cells.
• Analysis of RNA transcript expression patterns using techniques like in situ hybridization.
• Study of splice choice in transgenic mice using a metallothionein I promoter-calcitonin/CGRP fusion gene.

Main Results:

• Sm51 transcript is selectively expressed in rat brain and pituitary, while Sm11 transcript is abundant in heart.
• Sm51 and Sm11 likely encode brain and heart-specific 28-kDa snRNP-associated proteins, respectively.
• Sm51 RNA is found in neuronal structures, and its expression in the pituitary correlates with CGRP splice choice in transgenic mice.

Conclusions:

• Closely related snRNP-associated proteins exhibit discrete tissue-specific expression patterns.
• These proteins are potential mediators of differential RNA processing events, contributing to tissue-specific gene expression.
• While not solely sufficient, Sm51's expression pattern supports its role in CGRP splicing regulation.