Recruiting a Silent Partner for Activation of the Protein Kinase SRPK1

Aubol, Brandon E.; Adams, Joseph A.

doi:10.1021/bi500483m

Cited by 9 publications

(7 citation statements)

References 31 publications

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“…Expression and Purification of Recombinant Proteins. All forms of recombinant SRPK1 and SRSF1 were expressed and purified from pET19b vectors containing an N-terminal His tag as previously described (43). CLK1 virus was transfected and expressed in Hi5 insect cells, and CLK1 protein was purified with a nickel resin using a previously described procedure (20).…”

Section: Methodsmentioning

confidence: 99%

CLK1 reorganizes the splicing factor U1-70K for early spliceosomal protein assembly

Aubol

Wozniak

Fattet

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Early spliceosome assembly requires phosphorylation of U1-70K, a constituent of the U1 small nuclear ribonucleoprotein (snRNP), but it is unclear which sites are phosphorylated, and by what enzyme, and how such modification regulates function. By profiling the proteome, we found that the Cdc2-like kinase 1 (CLK1) phosphorylates Ser-226 in the C terminus of U1-70K. This releases U1-70K from subnuclear granules facilitating interaction with U1 snRNP and the serine-arginine (SR) protein SRSF1, critical steps in establishing the 5′ splice site. CLK1 breaks contacts between the C terminus and the RNA recognition motif (RRM) in U1-70K releasing the RRM to bind SRSF1. This reorganization also permits stable interactions between U1-70K and several proteins associated with U1 snRNP. Nuclear induction of the SR protein kinase 1 (SRPK1) facilitates CLK1 dissociation from U1-70K, recycling the kinase for catalysis. These studies demonstrate that CLK1 plays a vital, signal-dependent role in early spliceosomal protein assembly by contouring U1-70K for protein–protein multitasking.

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Section: Methodsmentioning

confidence: 99%

CLK1 reorganizes the splicing factor U1-70K for early spliceosomal protein assembly

Aubol

Wozniak

Fattet

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…All forms of recombinant SRPK1 and SRSF1 were expressed in E.coli and purified from pET19b vectors containing an N-terminal His tag as previously described [26]. CLK1 virus was transfected and expressed in Hi5 insect cells.…”

Section: Methodsmentioning

confidence: 99%

Mobilization of a splicing factor through a nuclear kinase–kinase complex

Aubol

Keshwani

Fattet

et al. 2018

Biochemical Journal

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The splicing of mRNA is dependent on serine-arginine (SR) proteins that are mobilized from membrane-free, nuclear speckles to the nucleoplasm by the Cdc2-like kinases (CLKs). This movement is critical for SR protein-dependent assembly of the macromolecular spliceosome. Although CLK1 facilitates such trafficking through the phosphorylation of serine-proline dipeptides in the prototype SR protein SRSF1, an unrelated enzyme known as SR protein kinase 1 (SRPK1) performs the same function but does not efficiently modify these dipeptides in SRSF1. We now show that the ability of SRPK1 to mobilize SRSF1 from speckles to the nucleoplasm is dependent on active CLK1. Diffusion from speckles is promoted by the formation of an SRPK1-CLK1 complex that facilitates dissociation of SRSF1 from CLK1 and enhances the phosphorylation of several serine-proline dipeptides in this SR protein. Down-regulation of either kinase blocks EGF-stimulated mobilization of nuclear SRSF1. These findings establish a signaling pathway that connects SRPKs to SR protein activation through the associated CLK family of kinases.

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“…RS domain proteins are involved in precursor mRNA translation, processing and splicing, chromatin reconstruction, cell cycle progression, and remodeling of cellular structures [9]. The spacer region of SRPK1 determines the cellular residence of SRPK1 that moves from cytoplasm to nuclei [10].…”

Section: Introductionmentioning

confidence: 99%

The crucial role of SRPK1 in TGF-β-induced proliferation and apoptosis in the esophageal squamous cell carcinomas

Ren

Sheng

et al. 2015

Med Oncol

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In recent years, transforming growth factor-β (TGF-β) and the serine-arginine protein kinase 1 (SRPK1) have been recommended as a key signal mediator that is involved in oncogenesis. However, the mechanisms underlying TGF-β-SRPK1 pathway-mediated proliferation and apoptosis in the esophageal squamous cell carcinomas (ESCC) have not been well featured till now. We used immunohistochemistry, immunoblotting, and RT-PCR to assess the expression of SRPK1 in 120 cases of ESCC samples and cell lines. Subsequently, some in vitro assays were also applied where cells were administrated with TGF-β. We found that SRPK1 was highly expressed in ESCC tissues and acts as an independent prognostic factor for ESCC patients. In vitro studies indicated that overexpression of wild-type SRPK1 promoted ESCC cell proliferation, while overexpression of the kinase-dead mutant of SRPK1 or RNA interference against SRPK1 suppressed cell growth and enhanced apoptosis. The knockdown of SRPK1 also inhibited subcutaneous xenografts' growth of ESCC cells in nude mice. Furthermore, Western bolt analysis showed SRPK1 can activate Akt phosphorylation and inhibit JNK phosphorylation. In conclusion, SRPK1 mediates TGF-β-induced proliferation and apoptosis by regulating AKT and JNK in ESCC, which indicates TGF-β-SRPK1 pathway may be suggested as a useful target to affect the progression of ESCC.

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Recruiting a Silent Partner for Activation of the Protein Kinase SRPK1

Cited by 9 publications

References 31 publications

CLK1 reorganizes the splicing factor U1-70K for early spliceosomal protein assembly

CLK1 reorganizes the splicing factor U1-70K for early spliceosomal protein assembly

Mobilization of a splicing factor through a nuclear kinase–kinase complex

The crucial role of SRPK1 in TGF-β-induced proliferation and apoptosis in the esophageal squamous cell carcinomas

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