Autocrine transforming growth factor-{beta}1 activation mediated by integrin {alpha}V{beta}3 regulates transcriptional expression of laminin-332 in Madin-Darby canine kidney epithelial cells.
Laminin (LM)-332 is an extracellular matrix protein that plays a structural role in normal tissues and is also important in facilitating recovery of epithelia from injury. We have shown that expression of LM-332 is up-regulated during renal epithelial regeneration after ischemic injury, but the molecular signals that control expression are unknown. Here, we demonstrate that in Madin-Darby canine kidney (MDCK) epithelial cells LM-332 expression occurs only in subconfluent cultures and is turned-off after a polarized epithelium has formed. Addition of active transforming growth factor (TGF)-β1 to confluent MDCK monolayers is sufficient to induce transcription of the LM α3 gene and LM-332 protein expression via the TGF-β type I receptor (TβR-I) and the Smad2-Smad4 complex. Significantly, we show that expression of LM-332 in MDCK cells is an autocrine response to endogenous TGF-β1 secretion and activation mediated by integrin αVβ3 because neutralizing antibodies block LM-332 production in subconfluent cells. In confluent cells, latent TGF-β1 is secreted apically, whereas TβR-I and integrin αVβ3 are localized basolaterally. Disruption of the epithelial barrier by mechanical injury activates TGF-β1, leading to LM-332 expression. Together, our data suggest a novel mechanism for triggering the production of LM-332 after epithelial injury.
Moyano
Jose V
JV
Department of Surgery, Committee on Cell Physiology, and Committee on Molecular Pathogenesis and Molecular Medicine, The University of Chicago, Chicago, IL 60637, USA. jvmoyano@uchicago.edu
Greciano
Patricia G
PG
Buschmann
Mary M
MM
Koch
Manuel
M
Matlin
Karl S
KS
D000818:Animals; D015815:Cell Adhesion Molecules / Q000096:biosynthesis* / Q000235:genetics; D002460:Cell Line; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005786:Gene Expression Regulation; D039302:Integrin alphaVbeta3 / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism; D051901:Smad4 Protein / Q000378:metabolism; D014158:Transcription, Genetic; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D039302:Integrin alphaVbeta3; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins; D051899:Smad2 Protein; D051901:Smad4 Protein; D053773:Transforming Growth Factor beta1; D000097794:Kalinin