Targeting of RBM10 to S1-1 Nuclear Bodies: Targeting Sequences and its Biological Significance

AbstractRBM10 is an RNA-binding protein that regulates alternative splicing (AS). This protein localizes to the extra-nucleolar nucleoplasm and S1-1 nuclear bodies (NBs). We investigated the biological significance of RBM10 localization to S1-1 NBs, which is poorly understood. Our analyses revealed that RBM10 possesses two S1-1 NB-targeting sequences (NBTSs), one in the KEKE motif region and another in the C2H2 Zn finger (ZnF). These NBTSs acted synergistically and were sufficient for localization of RBM10 to S1-1 NBs. Furthermore, the C2H2 ZnF not only acted as an NBTS, but was also essential for regulation of AS by RBM10. RBM10 did not participate in S1-1 NB formation. We confirmed the previous finding that localization of RBM10 to S1-1 NBs increases as cellular transcriptional activity decreases and vice versa. These results indicate that RBM10 is a transient component of S1-1 NBs and is sequestered in these structures via its NBTSs when cellular transcription decreases. We propose that the NB-targeting activity of the C2H2 ZnF is induced when it is not bound to pre-mRNA or the splicing machinery complex under conditions of reduced transcription.

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Sequestration of RBM10 in Nuclear Bodies: Targeting Sequences and Biological Significance

International Journal of Molecular Sciences ◽

10.3390/ijms221910526 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10526

Author(s):

Ling-Yu Wang ◽

Sheng-Jun Xiao ◽

Hiroyuki Kunimoto ◽

Kazuaki Tokunaga ◽

Hirotada Kojima ◽

...

Keyword(s):

Alternative Splicing ◽

Transcriptional Activity ◽

Rna Binding ◽

Rna Binding Protein ◽

Biological Significance ◽

Nuclear Bodies ◽

Deletion Mutants ◽

Molecular Function ◽

Protein Levels ◽

Cellular Transcription

RBM10 is an RNA-binding protein that regulates alternative splicing (AS). It localizes to the extra-nucleolar nucleoplasm and S1-1 nuclear bodies (NBs) in the nucleus. We investigated the biological significance of this localization in relation to its molecular function. Our analyses, employing deletion mutants, revealed that RBM10 possesses two S1-1 NB-targeting sequences (NBTSs), one in the KEKE motif region and another in the C2H2 Zn finger (ZnF). These NBTSs act synergistically to localize RBM10 to S1-1 NBs. The C2H2 ZnF not only acts as an NBTS, but is also essential for AS regulation by RBM10. Moreover, RBM10 does not participate in S1-1 NB formation, and without alterations of RBM10 protein levels, its NB-localization changes, increasing as cellular transcriptional activity declines, and vice versa. These results indicate that RBM10 is a transient component of S1-1 NBs and is sequestered in NBs via its NBTSs when cellular transcription decreases. We propose that the C2H2 ZnF exerts its NB-targeting activity when RBM10 is unbound by pre-mRNAs, and that NB-localization of RBM10 is a mechanism to control its AS activity in the nucleus.

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The RNA-binding protein Sam68 modulates the alternative splicing of Bcl-x

The Journal of Cell Biology ◽

10.1083/jcb.200701005 ◽

2007 ◽

Vol 176 (7) ◽

pp. 929-939 ◽

Cited By ~ 182

Author(s):

Maria Paola Paronetto ◽

Tilman Achsel ◽

Autumn Massiello ◽

Charles E. Chalfant ◽

Claudio Sette

Keyword(s):

Alternative Splicing ◽

Tyrosine Phosphorylation ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Live Cells ◽

Hnrnp A1 ◽

Splice Site Selection ◽

Subnuclear Localization ◽

Mrna Targets

The RNA-binding protein Sam68 is involved in apoptosis, but its cellular mRNA targets and its mechanism of action remain unknown. We demonstrate that Sam68 binds the mRNA for Bcl-x and affects its alternative splicing. Depletion of Sam68 by RNA interference caused accumulation of antiapoptotic Bcl-x(L), whereas its up-regulation increased the levels of proapoptotic Bcl-x(s). Tyrosine phosphorylation of Sam68 by Fyn inverted this effect and favored the Bcl-x(L) splice site selection. A point mutation in the RNA-binding domain of Sam68 influenced its splicing activity and subnuclear localization. Moreover, coexpression of ASF/SF2 with Sam68, or fusion with an RS domain, counteracted Sam68 splicing activity toward Bcl-x. Finally, Sam68 interacted with heterogenous nuclear RNP (hnRNP) A1, and depletion of hnRNP A1 or mutations that impair this interaction attenuated Bcl-x(s) splicing. Our results indicate that Sam68 plays a role in the regulation of Bcl-x alternative splicing and that tyrosine phosphorylation of Sam68 by Src-like kinases can switch its role from proapoptotic to antiapoptotic in live cells.

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