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A novel CDX2 isoform regulates alternative splicing.

Witek ME, Snook AE, Lin JE, Blomain ES, Xiang B, Magee MS, Magee M, Waldman SA - PLoS ONE (2014)

Bottom Line: CDX2/AS did not activate the CDX2-dependent promoter of guanylyl cyclase C nor inhibit transcriptional activity of CDX2.Unlike CDX2, CDX2/AS co-localized with the putative splicing factors ASF/SF2 and SC35.These data demonstrate unique dual functions of the CDX2 gene enabling it to regulate gene expression through both transcription (CDX2) and pre-mRNA processing (CDX2/AS).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Kimmel Cancer Center & Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America.

ABSTRACT
Gene expression is a dynamic and coordinated process coupling transcription with pre-mRNA processing. This regulation enables tissue-specific transcription factors to induce expression of specific transcripts that are subsequently amplified by alternative splicing allowing for increased proteome complexity and functional diversity. The intestine-specific transcription factor CDX2 regulates development and maintenance of the intestinal epithelium by inducing expression of genes characteristic of the mature enterocyte phenotype. Here, sequence analysis of CDX2 mRNA from colonic mucosa-derived tissues revealed an alternatively spliced transcript (CDX2/AS) that encodes a protein with a truncated homeodomain and a novel carboxy-terminal domain enriched in serine and arginine residues (RS domain). CDX2 and CDX2/AS exhibited distinct nuclear expression patterns with minimal areas of co-localization. CDX2/AS did not activate the CDX2-dependent promoter of guanylyl cyclase C nor inhibit transcriptional activity of CDX2. Unlike CDX2, CDX2/AS co-localized with the putative splicing factors ASF/SF2 and SC35. CDX2/AS altered splicing patterns of CD44v5 and Tra2-β1 minigenes in Lovo colon cancer cells independent of CDX2 expression. These data demonstrate unique dual functions of the CDX2 gene enabling it to regulate gene expression through both transcription (CDX2) and pre-mRNA processing (CDX2/AS).

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Co-localization of CDX2/AS with putative splicing factors.(A) F-IHC analysis of 293T and RKO cells transiently transfected with CDX2/AS-His and co-stained for CDX2/AS-His and either, SC35 or ASF/SF2. All proteins localized to the nucleus and merged images revealed co-localization of CDX2/AS with both SC35 and ASF/SF2. CDX2-Flag did not co-localize with either protein.
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pone-0104293-g005: Co-localization of CDX2/AS with putative splicing factors.(A) F-IHC analysis of 293T and RKO cells transiently transfected with CDX2/AS-His and co-stained for CDX2/AS-His and either, SC35 or ASF/SF2. All proteins localized to the nucleus and merged images revealed co-localization of CDX2/AS with both SC35 and ASF/SF2. CDX2-Flag did not co-localize with either protein.

Mentions: To investigate a possible role for CDX2/AS in alternative splicing, we performed F-IHC co-localization studies in transiently transfected 293T cells. Indeed, CDX2/AS co-localized with the putative SR splicing factors ASF/SF2 and SC35 whereas CDX2 did not. To confirm these findings in an endogenous system, F-IHC was performed using RKO human colorectal cells. As in 293T cells, CDX2/AS, but not CDX2, co-localized with nuclear ASF/SF2 and SC35 (Fig. 5).


A novel CDX2 isoform regulates alternative splicing.

Witek ME, Snook AE, Lin JE, Blomain ES, Xiang B, Magee MS, Magee M, Waldman SA - PLoS ONE (2014)

Co-localization of CDX2/AS with putative splicing factors.(A) F-IHC analysis of 293T and RKO cells transiently transfected with CDX2/AS-His and co-stained for CDX2/AS-His and either, SC35 or ASF/SF2. All proteins localized to the nucleus and merged images revealed co-localization of CDX2/AS with both SC35 and ASF/SF2. CDX2-Flag did not co-localize with either protein.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4125279&req=5

pone-0104293-g005: Co-localization of CDX2/AS with putative splicing factors.(A) F-IHC analysis of 293T and RKO cells transiently transfected with CDX2/AS-His and co-stained for CDX2/AS-His and either, SC35 or ASF/SF2. All proteins localized to the nucleus and merged images revealed co-localization of CDX2/AS with both SC35 and ASF/SF2. CDX2-Flag did not co-localize with either protein.
Mentions: To investigate a possible role for CDX2/AS in alternative splicing, we performed F-IHC co-localization studies in transiently transfected 293T cells. Indeed, CDX2/AS co-localized with the putative SR splicing factors ASF/SF2 and SC35 whereas CDX2 did not. To confirm these findings in an endogenous system, F-IHC was performed using RKO human colorectal cells. As in 293T cells, CDX2/AS, but not CDX2, co-localized with nuclear ASF/SF2 and SC35 (Fig. 5).

Bottom Line: CDX2/AS did not activate the CDX2-dependent promoter of guanylyl cyclase C nor inhibit transcriptional activity of CDX2.Unlike CDX2, CDX2/AS co-localized with the putative splicing factors ASF/SF2 and SC35.These data demonstrate unique dual functions of the CDX2 gene enabling it to regulate gene expression through both transcription (CDX2) and pre-mRNA processing (CDX2/AS).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Kimmel Cancer Center & Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America.

ABSTRACT
Gene expression is a dynamic and coordinated process coupling transcription with pre-mRNA processing. This regulation enables tissue-specific transcription factors to induce expression of specific transcripts that are subsequently amplified by alternative splicing allowing for increased proteome complexity and functional diversity. The intestine-specific transcription factor CDX2 regulates development and maintenance of the intestinal epithelium by inducing expression of genes characteristic of the mature enterocyte phenotype. Here, sequence analysis of CDX2 mRNA from colonic mucosa-derived tissues revealed an alternatively spliced transcript (CDX2/AS) that encodes a protein with a truncated homeodomain and a novel carboxy-terminal domain enriched in serine and arginine residues (RS domain). CDX2 and CDX2/AS exhibited distinct nuclear expression patterns with minimal areas of co-localization. CDX2/AS did not activate the CDX2-dependent promoter of guanylyl cyclase C nor inhibit transcriptional activity of CDX2. Unlike CDX2, CDX2/AS co-localized with the putative splicing factors ASF/SF2 and SC35. CDX2/AS altered splicing patterns of CD44v5 and Tra2-β1 minigenes in Lovo colon cancer cells independent of CDX2 expression. These data demonstrate unique dual functions of the CDX2 gene enabling it to regulate gene expression through both transcription (CDX2) and pre-mRNA processing (CDX2/AS).

Show MeSH
Related in: MedlinePlus