A myosin chaperone, UNC-45A, is a novel regulator of intestinal epithelial barrier integrity and repair

• Published in: bioRxiv
• Main Authors: Lechuga, Susana, Cartagena-Rivera, Alexander X., Khan, Afshin, Crawford, Bert I., Narayanan, Vani, Conway, Daniel E., Lehtimäki, Jaakko, Lappalainen, Pekka, Rieder, Florian, Longworth, Michelle S., Ivanov, Andrei I.
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Laboratory 11.11.2021
• Edition: 1.1
• Subjects: Cell Biology
• ISSN: 2692-8205
• DOI: 10.1101/2021.11.10.467974

The actomyosin cytoskeleton serves as a key regulator of the integrity and remodeling of epithelial barriers by controlling assembly and functions of intercellular junctions and cell-matrix adhesions. While biochemical mechanisms that regulate activity of non-muscle myosin II (NM-II) in epithelial cells have been extensively investigated, little is known about assembly of the contractile myosin structures at the epithelial adhesion sites. UNC-45A is a cytoskeletal chaperone that is essential for proper folding of NM II heavy chains and myofilament assembly. We found abundant expression of UNC-45A in human intestinal epithelial cell (IEC) lines and in the epithelial layer of the normal human colon. Interestingly, protein levels of UNC-45A were decreased in colonic epithelium of patients with ulcerative colitis. CRISPR/Cas9-mediated knock-out of UNC-45A in HT-29 and SK-CO15 IEC disrupted epithelial barrier integrity, impaired assembly of epithelial adherence and tight junctions and attenuated cell migration. Consistently, decreased UNC-45 expression increased permeability of the Drosophila gut in vivo. The mechanisms underlying barrier disruptive and anti-migratory effects of UNC-45A depletion involved disorganization of the actomyosin bundles at epithelial junctions and the migrating cell edge. Loss of UNC-45A also decreased contractile forces at epithelial junctions and matrix adhesions. Expression of deletion mutants revealed roles for the myosin binding domain of UNC-45A in controlling IEC junctions and motility. Our findings uncover a novel mechanism that regulates integrity and restitution of the intestinal epithelial barrier, which may be impaired during mucosal inflammation.