Phosphorylation of the alternative mRNA splicing factor 45 (SPF45) by Clk1 regulates its splice site utilization, cell migration and invasion

Yuying Liu; LaShardai Conaway; Jennifer Rutherford Bethard; Adnan M. Al-Ayoubi; Amber Thompson Bradley; Hui Zheng; Scott A. Weed; Scott T. Eblen

doi:10.1093/nar/gkt170

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Phosphorylation of the alternative mRNA splicing factor 45 (SPF45) by Clk1 regulates its splice site utilization, cell migration and invasion

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Phosphorylation of the alternative mRNA splicing factor 45 (SPF45) by Clk1 regulates its splice site utilization, cell migration and invasion

Yuying Liu, LaShardai Conaway, Jennifer Rutherford Bethard, Adnan M. Al-Ayoubi, Amber Thompson Bradley, Hui Zheng, Scott A. Weed and Scott T. Eblen

Nucleic acids research, Vol.41(9), pp.4949-4962

05/01/2013

DOI: 10.1093/nar/gkt170

PMCID: PMC3643583

PMID: 23519612

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Abstract

Alternative mRNA splicing is a mechanism to regulate protein isoform expression and is regulated by alternative splicing factors. The alternative splicing factor 45 (SPF45) is overexpressed in cancer, although few biological effects of SPF45 are known, and few splicing targets have been identified. We previously showed that Extracellular Regulated Kinase 2 (ERK2) phosphorylation of SPF45 regulates cell proliferation and adhesion to fibronectin. In this work, we show that Cdc2-like kinase 1 (Clk1) phosphorylates SPF45 on eight serine residues. Clk1 expression enhanced, whereas Clk1 inhibition reduced, SPF45-induced exon 6 exclusion from Fas mRNA. Mutational analysis of the Clk1 phosphorylation sites on SPF45 showed both positive and negative regulation of splicing, with a net effect of inhibiting SPF45-induced exon 6 exclusion, correlating with reduced Fas mRNA binding. However, Clk1 enhanced SPF45 protein expression, but not mRNA expression, whereas inhibition of Clk1 increased SPF45 degradation through a proteasome-dependent pathway. Overexpression of SPF45 or a phospho-mimetic mutant, but not a phospho-inhibitory mutant, stimulated ovarian cancer cell migration and invasion, correlating with increased fibronectin expression, ERK activation and enhanced splicing and phosphorylation of full-length cortactin. Our results demonstrate for the first time that SPF45 overexpression enhances cell migration and invasion, dependent on biochemical regulation by Clk1.

Molecular Biology

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Title: Subtitle: Phosphorylation of the alternative mRNA splicing factor 45 (SPF45) by Clk1 regulates its splice site utilization, cell migration and invasion
Creators: Yuying Liu - Medical University of South Carolina
LaShardai Conaway - Medical University of South Carolina
Jennifer Rutherford Bethard - Medical University of South Carolina
Adnan M. Al-Ayoubi - Medical University of South Carolina
Amber Thompson Bradley - Medical University of South Carolina
Hui Zheng - Medical University of South Carolina
Scott A. Weed - Medical University of South Carolina
Scott T. Eblen - Medical University of South Carolina
Resource Type: Journal article
Publication Details: Nucleic acids research, Vol.41(9), pp.4949-4962
DOI: 10.1093/nar/gkt170
PMID: 23519612
PMCID: PMC3643583
NLM abbreviation: Nucleic Acids Res
ISSN: 0305-1048
eISSN: 1362-4962
Publisher: Oxford University Press
Number of pages: 14
Language: English
Date published: 05/01/2013
Academic Unit: Cardiothoracic Surgery
Record Identifier: 9984701732502771

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