TRPV4-dependent induction of a novel mammalian cold-inducible protein SRSF5 as well as CIRP and RBM3

Takanori Fujita,Motoi Fukumoto,Hiroyuki Nishiyama,Takahiro Kojima,Yu Liu,Manabu Fukumoto,Hisako Higashitsuji,Toshiharu Sakurai,Jun Fujita,Hiroaki Higashitsuji,Koji Shibasaki,Shuya Kandori,Katsuhiko Itoh

doi:10.1038/s41598-017-02473-x

Abstract

Cold-inducible RNA-binding protein (CIRP) and RNA-binding motif protein 3 (RBM3) are two evolutionarily conserved RNA-binding proteins that are structurally related to hnRNPs and upregulated in response to moderately low temperatures in mammalian cells. Although contributions of splicing efficiency, the gene promoters activated upon mild hypothermia and the transcription factor Sp1 to induction of CIRP have been reported, precise mechanisms by which hypothermia and other stresses induce the expression of mammalian cold-inducible proteins (CIPs) are poorly understood. By screening the serine/arginine-rich splicing factors (SRSFs), we report that the transcript and protein levels of SRSF5 were increased in mammalian cells cultured at 32 °C. Expression of SRSF5 as well as CIRP and RBM3 were also induced by DNA damage, hypoxia, cycloheximide and hypotonicity. Immunohistochemical studies demonstrated that SRSF5 was constitutively expressed in male germ cells and the level was decreased in human testicular germ cell tumors. SRSF5 facilitated production of p19 H-RAS, and increased sensitivity to doxorubicin in human U-2 OS cells. Induction of CIPs was dependent on transient receptor potential vanilloid 4 (TRPV4) channel protein, but seemed independent of its ion channel activity. These findings indicate a previously unappreciated role for the TRP protein in linking environmental stress to splicing.

Highlights

By screening the serine/arginine-rich splicing factors (SRSFs), we report that the transcript and protein levels of SRSF5 were increased in mammalian cells cultured at 32 °C
We found that SRSF5 protein is inducible by mild hypothermia and other stresses like Cold-inducible RNA-binding protein (CIRP) and RNA-binding motif protein 3 (RBM3)
Hypothermia induced SRSF5 protein in mouse embryonic fibroblasts derived from wild-type and CIRP-knockout (KO) mice, NIH/3T3 cells, human HEK293 cells and NC65 cells (Supplementary Fig. S1)

Summary

Introduction

Induction of CIPs was dependent on transient receptor potential vanilloid 4 (TRPV4) channel protein, but seemed independent of its ion channel activity These findings indicate a previously unappreciated role for the TRP protein in linking environmental stress to splicing. The transient receptor potential (TRP) channels are, in general, non-selective cation channels that open in response to changes in temperature, ligand binding and other alterations of the channel protein[1, 2]. They play major roles in a variety of sensory modalities such as vision, thermosensation, olfaction, hearing, taste sensation, and mechanosensation, allowing animals to perceive the external environment. TRPV3 and TRPV4 have been proposed to be molecular sensors that are involved in the detection of non-noxious warmth

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Conclusion