ABSTRACT
Pre-mRNA splicing is widely repressed upon heat shock in eukaryotic cells. However, it has been shown that HSP105 pre-mRNA is alternatively spliced in response to heat stress. Using RNAi screening in HeLa cells, we found that RNA-binding proteins hnRNP K and PSF/SFPQ are necessary for the exon 12 exclusion of HSP105 during heat stress. Moreover, exon array analyses showed that a group of genes is alternatively spliced during heat stress in an hnRNP K-dependent manner, whereas hnRNP K is not necessary for the stress-induced alternative splicing of the remaining genes. Among the latter group, we found that SRp38/SRSF10 and SC35/SRSF2 are necessary for the inclusion of exon 13 of TNRC6A during heat stress. Thus, our study clearly showed that several RNA-binding proteins are involved in the splicing regulation in response to heat stress in mammalian cells.
Subject(s)
Alternative Splicing , HSP110 Heat-Shock Proteins/genetics , Heat-Shock Response/genetics , Heterogeneous-Nuclear Ribonucleoprotein K/genetics , Exons , HSP110 Heat-Shock Proteins/metabolism , HeLa Cells , Heterogeneous-Nuclear Ribonucleoprotein K/metabolism , Humans , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , PTB-Associated Splicing Factor/genetics , PTB-Associated Splicing Factor/metabolism , RNA Precursors/genetics , RNA Precursors/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Ribonucleoproteins/genetics , Ribonucleoproteins/metabolismABSTRACT
HERMES, also called RBPMS, is a conserved RNA binding protein with a single RNA recognition motif (RRM) that is abundantly expressed in retinal ganglion cells (RGCs) and in the heart in vertebrates. Here, we identified NonO and PSF as the interacting proteins of HERMES only when the neuronal differentiation of the retinal cell line RGC-5 was induced. Although NonO and PSF are nuclear paraspeckle components, these proteins formed cytoplasmic granules with HERMES in the neurites. G3BP1, a component of stress granules, was also colocalized to the granules, interacting with NonO and HERMES even in the absence of cellular stress. Consistent with a previous report that KIF5 interacts with neuronal granules, the localization of KIF5A overlapped with the cytoplasmic granules in differentiated RGC-5 cells. Thus, our study strongly suggests that the cytoplasmic granule containing HERMES, NonO, PSF, and G3BP1 is a neuronal RNA-protein granule that is transported in neurites during retinal differentiation.
