Pre-messenger RNA cleavage factor I (CFIm): potential role in alternative polyadenylation during spermatogenesis

Area of Science:

• Molecular Biology
• Genetics
• Reproductive Biology

Background:

• Alternative polyadenylation generates cell-specific mRNAs in male germ cells, often using noncanonical polyadenylation signals.
• Cleavage factor I (CFIm) influences polyadenylation site selection in somatic cells.

Purpose of the Study:

• To investigate the role of CFIm subunits in male germ cell gene expression and alternative polyadenylation.
• To determine the expression patterns and regulation of CFIm subunits during spermatogenesis.

Main Methods:

• Comparative analysis of CFIm subunit (NUDT21/CPSF5, CPSF6) enrichment in mouse male germ cells versus somatic cells.
• mRNA sequencing and Northern blotting to analyze Nudt21 and Cpsf6 mRNA isoforms.
• Identification of CFIm binding sites in 3'-untranslated regions of germ cell transcripts.

Main Results:

• NUDT21/CPSF5 and CPSF6 are highly enriched in male germ cells.
• Shorter Nudt21 and Cpsf6 mRNA variants, generated by alternative polyadenylation, are found in spermatogenic cells.
• CFIm binding sites in 3'-UTRs suggest autoregulation of CFIm subunit expression.
• CFIm subunit levels vary during spermatogenesis, indicating stage-specific regulation.
• CFIm binding sites are prevalent near the 3' ends of male germ cell transcripts using noncanonical polyadenylation signals.

Conclusions:

• CFIm complexes are likely involved in directing alternative polyadenylation mediated by noncanonical poly(A) signals in male germ cells.
• Autoregulation and stage-dependent regulation of CFIm subunits contribute to germ cell-specific mRNA processing.