An ancient testis-specific IQ motif-containing H gene regulates specific transcript isoform expression during...

Area of Science:

• Molecular Biology
• Genetics
• Reproductive Biology

Background:

• Spermatogenic cells exhibit complex alternative splicing (AS) patterns, but the regulatory mechanisms remain largely unknown.
• Alternative splicing is critical for generating diverse protein isoforms essential for cellular function.

Purpose of the Study:

• To investigate the function of the testis-specific IQ motif-containing H gene (Iqch) in spermatogenesis.
• To elucidate the role of Iqch in the regulation of RNA splicing and gene expression during male germ cell development.

Main Methods:

• Utilized a mutant mouse model to study Iqch function.
• Employed immunohistochemistry to determine Iqch localization within testicular cells.
• Performed RNA sequencing (RNA-seq) to analyze gene expression and splicing alterations in wild-type and mutant mice.

Main Results:

• Iqch is essential for specific RNA isoform expression during spermatogenesis, localized to the nucleus of spermatocytes and spermatids.
• Mutant Iqch led to downregulation of testis-specific long non-coding RNAs (lncRNAs) and protein-coding genes at the spermatid stage.
• Significant AS modifications, primarily increased intron retention, were observed in mutant Iqch, resulting in male infertility.
• Identified novel spliced transcripts in wild-type testes and observed altered isoform usage in mutants, favoring canonical forms.

Conclusions:

• Iqch plays a vital role in a splicing control mechanism essential for germ cell biology.
• Disruption of Iqch function severely impacts RNA splicing, leading to male infertility.
• Iqch interacts with SRRM2 and ERSP1 in nuclear speckles, suggesting a coordinated regulation of alternative splicing.