Development and function of smooth muscle cells is modulated by Hic1 in mouse testis

Area of Science:

• Reproductive biology
• Developmental biology
• Molecular genetics

Background:

• Peritubular myoid cells (PMCs) are crucial for mammalian testicular function, supporting the stem cell niche.
• The role of testicular smooth muscle cells in postnatal testicular development remains largely unexplored.
• Hypermethylated in cancer 1 (Hic1) is a gene with potential roles in cell growth and differentiation.

Purpose of the Study:

• To investigate the age-dependent expression of Hic1 in testicular smooth muscle cells.
• To determine the function of Hic1 in regulating postnatal testicular smooth muscle cell proliferation and function.
• To elucidate the impact of Hic1 on seminiferous tubule development and spermatogenesis.

Main Methods:

• Analysis of age-dependent Hic1 expression in mouse testicular smooth muscle cells (PMCs and vascular smooth muscle cells).
• Generation of mice with postnatal deletion of Hic1 specifically in smooth muscle cells.
• Histological and molecular analyses of testicular structure, cell populations, basement membrane components, and gene expression in Hic1-deficient mice.

Main Results:

• Hic1 expression is observed in testicular smooth muscle cells during postnatal development.
• Postnatal deletion of Hic1 leads to increased proliferation of smooth muscle cells, seminiferous tubule dilatation, and increased PMC numbers.
• Hic1 deficiency results in fewer Sertoli cells, more spermatogonia, absence of fibronectin in the basement membrane, and reduced expression of smooth muscle contractile genes (Acta2, Cnn1), leading to impaired tubule contractility.

Conclusions:

• Hic1 plays a critical role in regulating postnatal smooth muscle cell proliferation in the testis.
• Hic1 is essential for maintaining seminiferous tubule size and basement membrane integrity.
• Disruption of Hic1 function negatively impacts spermatogenesis by affecting testicular cell composition and function.