Epithelial JAM-A is fundamental for intestinal wound repair in vivo
Shuling Fan, … , Miguel Quiros, Charles A. Parkos
Shuling Fan, … , Miguel Quiros, Charles A. Parkos
Published August 9, 2022
Citation Information: JCI Insight. 2022;7(17):e158934. https://doi.org/10.1172/jci.insight.158934.
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Research Article Cell biology Gastroenterology

Epithelial JAM-A is fundamental for intestinal wound repair in vivo

Abstract

Junctional adhesion molecule-A (JAM-A) is expressed in several cell types, including epithelial and endothelial cells, as well as some leukocytes. In intestinal epithelial cells (IEC), JAM-A localizes to cell junctions and plays a role in regulating barrier function. In vitro studies with model cell lines have shown that JAM-A contributes to IEC migration; however, in vivo studies investigating the role of JAM-A in cell migration–dependent processes such as mucosal wound repair have not been performed. In this study, we developed an inducible intestinal epithelial–specific JAM-A–knockdown mouse model (Jam-aERΔIEC). While acute induction of IEC-specific loss of JAM-A did not result in spontaneous colitis, such mice had significantly impaired mucosal healing after chemically induced colitis and after biopsy colonic wounding. In vitro primary cultures of JAM-A–deficient IEC demonstrated impaired migration in wound healing assays. Mechanistic studies revealed that JAM-A stabilizes formation of protein signaling complexes containing Rap1A/Talin/β1 integrin at focal adhesions of migrating IECs. Loss of JAM-A in primary IEC led to decreased Rap1A activity and protein levels of Talin and β1 integrin, and it led to a reduction in focal adhesion structures. These findings suggest that epithelial JAM-A plays a critical role in controlling mucosal repair in vivo through dynamic regulation of focal adhesions.

Authors

Shuling Fan, Kevin Boerner, Chithra K. Muraleedharan, Asma Nusrat, Miguel Quiros, Charles A. Parkos

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Figure 2

Epithelial expressed JAM-A is required for recovery from DSS-induced mucosal injury in vivo.

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Epithelial expressed JAM-A is required for recovery from DSS-induced muc...
(A) Naive and tamoxifen-treated Jam-afl/fl and Jam-aERΔIEC mice were analyzed for expression of Jam-a in IEC. Mice were treated with tamoxifen to induce acute depletion of JAM-A specifically in IEC and analyzed 30 days after treatment. Freshly frozen sections of colonic mucosa from tamoxifen-treated Jam-afl/fl and Jam-aERΔIEC mice were stained with anti–JAM-A antibody (white). Following tamoxifen treatment, JAM-A expression was observed to be depleted in IEC and preserved in lamina propria cells of Jam-aERΔIEC mice. Scale bars: 100 μm. (B) After withdrawal of DSS, mice lacking epithelial JAM-A (Jam-aERΔIEC) exhibited greater body weight loss and worse clinical scores (DAI) compared with controls. Data are representative of 2 independent experiments with 6 animals per group and are expressed as mean ± SEM. *P < 0.05, **P < 0.01, and ***P < 0.001 by 2-way ANOVA. (C) Representative H&E staining of colon tissue harvested after 5 days of recovery revealed extensive mucosal injury, erosion, and ulceration in Jam-aERΔIEC mice compared with controls. Scale bars: 800 μm. Results are representative of 2 independent experiments with 3 animals per group. (D) Histological analysis of H&E-stained tissue sections of colon mucosa as seen in C. After 5 days of recovery on water, HCS in Jam-aERΔIEC mice revealed greater mucosal damage following depletion of epithelial JAM-A. Jam-aERΔIEC colon tissue contained more areas with mucosal injury and eroded/ulcerated regions compared with control tissue. Dots represent individual mice. Data are representative of 2 independent experiments with 3 animals per group and are expressed as mean ± SEM. *P < 0.05 by 2-tailed Student’s t test.