Secreted cyclophilin A, a peptidylprolyl cis-trans isomerase, mediates matrix assembly of hensin, a protein implicated in epithelial differentiation.
Hensin is a rabbit ortholog of DMBT1, a multifunctional, multidomain protein implicated in the regulation of epithelial differentiation, innate immunity, and tumorigenesis. Hensin in the extracellular matrix (ECM) induced morphological changes characteristic of terminal differentiation in a clonal cell line (clone C) of rabbit kidney intercalated cells. Although hensin is secreted in monomeric and various oligomeric forms, only the polymerized ECM form is able to induce these phenotypic changes. Here we report that hensin secretion and matrix assembly were inhibited by the peptidylprolyl cis-trans isomerase (PPIase) inhibitors cyclosporin A (CsA) and a derivative of cyclosporin A with modifications in the d-Ser side chain (Cs9) but not by the calcineurin pathway inhibitor FK506. PPIase inhibition led to failure of hensin polymerization in the medium and ECM, plus the loss of apical cytoskeleton, apical microvilli, and the columnar epithelial shape of clone C cells. Cyclophilin A was produced and secreted into the media to a much greater extent than cyclophilins B and C. Our results also identified the direct CsA-sensitive interaction of cyclophilin A with hensin, suggesting that cyclophilin A is the PPIase that mediates the polymerization and matrix assembly of hensin. These results are significant because this is the first time a direct role of peptidylprolyl cis-trans isomerase activity has been implicated in the process of epithelial differentiation.
Peng
Hu
H
Department of Pediatrics, University of Rochester School of Medicine, Rochester, New York 14642, USA.
Vijayakumar
Soundarapandian
S
Schiene-Fischer
Cordelia
C
Li
Hui
H
Purkerson
Jeffrey M
JM
Malesevic
Miroslav
M
Liebscher
Jürgen
J
Al-Awqati
Qais
Q
Schwartz
George J
GJ
D000818:Animals; D002460:Cell Line; D021984:Cyclophilin A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D011817:Rabbits; D051116:Receptors, Scavenger; D016559:Tacrolimus / Q000494:pharmacology
D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D007166:Immunosuppressive Agents; D051116:Receptors, Scavenger; C495130:hensin protein, rabbit; D016572:Cyclosporine; D021984:Cyclophilin A; D016559:Tacrolimus