Enterocyte STAT5 promotes mucosal wound healing via suppression of myosin light chain kinase-mediated loss of barrier function and inflammation.
Bottom Line: However, mechanism, redundancy by STAT5 or cell types involved remained foggy.Consistently, knockdown of stat5 in IEC monolayers led to increased NF-κB DNA binding to MLCK promoter, myosin light chain phosphorylation and tight junction (TJ) permeability, which were potentiated by administration of tumour necrosis factor-α (TNF-α), and prevented by concurrent NF-κB knockdown.Targeting IEC STAT5 signalling may be a novel therapeutic approach for treating intestinal barrier dysfunction in IBD.
Affiliation: Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, OH, USA.Show MeSH
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Mentions: To further demonstrate that STAT5 regulates NF-κB activity in IECs, further modulates MLC phosphorylation, we performed a simultaneous knockdown of STAT5 and RelA/p65 in HT-29 monolayers. We observed that paracellular permeability was increased in STAT5 knockdown monolayers, but not in HT-29 monolayers following RelA/p65 knock down (Fig 9A). Monolayer permeability induced by STAT5 knockdown was further potentiated by IFN-γ (10 ng/ml) and TNF-α (10 ng/ml) co-administration, while RelA/p65 knockdown promoted resistance of proinflammatory cytokine-induced hyperpermeability in monolayers (Fig 9A). Surprisingly, STAT5 and RelA/p65 double knockdown rescued the hyperpermeability that was induced by pro-inflammatory cytokines in single STAT5 knockdown monolayers (Fig 9A). Thus, the reduction of NF-κB may prevent hyperpermeability caused by the loss of STAT5 in IEC monolayers. Furthermore, we consistently found that STAT5 knockdown increased the levels of pMLC and potentiated cytokine-induced pMLC, which was restored by concurrent RelA/p65 knockdown (Fig 9B). Knockdown of STAT5 and basolateral stimulation with cytokines, however, did not increase the expression of the pro-apoptotic protein Bax (Fig 9B). Taken together, STAT5 in enterocytes may negatively regulate NF-κB activation of MLCK and facilitates the protection of intestinal hyperpermeability induced by pro-inflammatory cytokines (STAT5⊣ NF-κB → MLCK; Fig 9C).
Affiliation: Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, OH, USA.