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Published on: February 8, 2016
Decreased expression of mouse Rbm3, a cold-shock protein, in Sertoli cells of cryptorchid testis
1Department of Clinical Molecular Biology, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Abstract:
Physiological scrotal hypothermia is necessary for normal spermatogenesis and fertility in mammals. Human RNA binding motif protein 3 (RBM3) is structurally highly similar to the cold-inducible RNA-binding protein (Cirp), and both mRNAs are induced in human cells at the scrotal temperature (32 degrees C). We report here the cloning of mouse Rbm3 cDNA, which encoded an 18-kd protein with 94% identity in amino acid sequence to that of human RBM3. In the testis of adult mice, Rbm3 mRNA and protein were detected in Sertoli cells, but not germ cells, of seminiferous tubules at all stages. The expression was not observed in Sertoli cells of fetuses, but was observed in newborn and older mice. In the TAMA26 mouse Sertoli cell line, the Rbm3 expression level was increased or decreased within 12 hours after temperature shift from 37 degrees C to 32 degrees C or 39 degrees C, respectively. In contrast to Cirp, the cold-induced growth suppression of TAMA26 cells was not affected by suppression of the Rbm3 expression. When mouse testis was exposed to heat stress by experimental cryptorchidism, the level of Rbm3 was decreased in Sertoli cells. Rbm3 may play important roles distinct from those played by Cirp in spermatogenesis and cryptorchidism by regulating the gene expression in Sertoli cells.
Insights
RNA binding motif protein 3 (RBM3) is crucial for male fertility, with expression in mouse testes responding to temperature changes. RBM3 plays roles in spermatogenesis and heat stress, distinct from Cirp.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Cell Biology
Background:
- Spermatogenesis and mammalian fertility depend on physiological scrotal hypothermia.
- RNA binding motif protein 3 (RBM3) and cold-inducible RNA-binding protein (Cirp) are cold-induced proteins.
- RBM3 shares structural similarity with Cirp, with both mRNAs upregulated at scrotal temperatures.
Purpose of the Study:
- To clone mouse Rbm3 cDNA and characterize its expression and function in the testis.
- To investigate the role of RBM3 in Sertoli cells under varying temperatures and heat stress.
- To compare the function of RBM3 with Cirp in cellular responses to cold.
Main Methods:
- Cloning of mouse Rbm3 cDNA and sequencing.
- Detection of Rbm3 mRNA and protein in mouse testes using various stages and ages.
- Analysis of Rbm3 expression in TAMA26 mouse Sertoli cell line after temperature shifts.
- Assessment of Rbm3 levels during experimental cryptorchidism (heat stress).
Main Results:
- Mouse Rbm3 cDNA encodes an 18-kd protein with 94% amino acid identity to human RBM3.
- Rbm3 mRNA and protein are present in adult mouse Sertoli cells, but not germ cells, and expression increases after birth.
- Rbm3 expression in TAMA26 cells is temperature-dependent, increasing at 32°C and decreasing at 39°C.
- Rbm3 is downregulated in Sertoli cells under heat stress induced by cryptorchidism.
- Suppression of Rbm3 did not affect cold-induced growth suppression in TAMA26 cells, unlike Cirp.
Conclusions:
- Rbm3 is expressed in adult mouse Sertoli cells and its expression is regulated by temperature.
- Rbm3 plays a role in spermatogenesis and responds to heat stress (cryptorchidism) in a manner distinct from Cirp.
- RBM3 may regulate gene expression in Sertoli cells, contributing to distinct functions in spermatogenesis and response to testicular heat stress.
