Rab25 regulates integrin expression in polarized colonic epithelial cells.
Rab25 is a tumor suppressor for colon cancer in humans and mice. To identify elements of intestinal polarity regulated by Rab25, we developed Caco2-BBE cell lines stably expressing short hairpin RNA for Rab25 and lines rescuing Rab25 knockdown with reexpression of rabbit Rab25. Rab25 knockdown decreased α2-, α5-, and β1-integrin expression. We observed colocalization and direct association of Rab25 with α5β1-integrins. Rab25 knockdown also up-regulated claudin-1 expression, increased transepithelial resistance, and increased invasive behavior. Rab25-knockdown cells showed disorganized brush border microvilli with decreases in villin expression. All of these changes were reversed by reintroduction of rabbit Rab25. Rab25 knockdown altered the expression of 29 gene transcripts, including the loss of α5-integrin transcripts. Rab25 loss decreased expression of one transcription factor, ETV4, and overexpression of ETV4 in Rab25-knockdown cells reversed losses of α5β1-integrin. The results suggest that Rab25 controls intestinal cell polarity through the regulation of gene expression.
Section of Surgical Sciences and the Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Moorthy
M
Krishnan
Lynne A
LA
Lapierre
Byron C
BC
Knowles
James R
JR
Goldenring
D017500:Adenovirus E1A Proteins / Q000378:metabolism; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D016764:Cell Polarity; D062445:Claudin-1 / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D006801:Humans; D039421:Integrin alpha2 / Q000378:metabolism; D039482:Integrin alpha5 / Q000235:genetics / Q000378:metabolism; D039081:Integrin alpha5beta1 / Q000378:metabolism; D019012:Integrin beta1 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008871:Microvilli / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050783:Proto-Oncogene Proteins c-ets; D034622:RNA Interference; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D017500:Adenovirus E1A Proteins; D062445:Claudin-1; C079853:ETV4 protein, human; D039421:Integrin alpha2; D039482:Integrin alpha5; D039081:Integrin alpha5beta1; D019012:Integrin beta1; D016023:Integrins; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; C509763:Rab25 protein, human; D020691:rab GTP-Binding Proteins