MCL-1 is modulated in Crohn?s disease fibrosis by miR-29b via IL-6 and IL-8

ANKE NIJHUIS; ROGER FEAKINS; SHAMEER MEHTA; ANDREW SILVER; RENATA CURCIARELLO; JAMES O LINDSAY

CELL AND TISSUE RESEARCH

SPRINGER

Lugar: Berlin; Año: 2017

0302-766X

The miR-29 family is involved in fibrosis in multiple organs, including the intestine wheremiR-29b facilitates TGF-β-mediated up-regulation of collagen in mucosal fibroblasts fromCrohn?s disease (CD) patients. Myeloid cell leukemia-1 (MCL-1), a member of the B-cellCLL/Lymphoma 2 (BCL-2) apoptosis family is involved in liver fibrosis and is targeted bymiR-29b via its 3?-UTR in cultured cell lines. We investigated the role of MCL-1 and miR-29b in primary intestinal fibroblasts and tissue from structuring CD patients. Transfection ofCD intestinal fibroblasts with pre-miR-29b resulted in a significant increase in the mRNAexpression of MCL-1 isoforms (MCL-1Long (L)/Extra Short (ES) and MCL-1Short (S)),although MCL-1S was expressed at significantly lower levels. Western blotting detected theanti-apoptotic MCL-1L isoform predominantly, and immunofluorescence showed stainingwas localised in discrete nuclear foci. Transfection with pre-miR-29b or anti-miR-29bresulted in a significant increase or decrease, respectively, in MCL-1L foci. CD fibroblaststreated with IL-6 and IL-8, inflammatory cytokines upstream of MCL-1, increased the totalmass of MCL-1L-positive foci. Furthermore, transfection of intestinal fibroblasts with premiR-29bresulted in an increase in mRNA and protein levels of IL-6 and IL-8. Finally,immunohistochemistry showed reduced MCL-1 protein expression in fibrotic CD samplescompared to non-stricturing controls. Together, our findings suggest that induction of MCL-1by IL-6/IL-8 may surmount any direct down-regulation by miR-29b via its 3?-UTR. Wepropose that an anti-fibrotic miR-29b/IL-6 IL-8/MCL-1L axis may influence intestinalfibrosis in CD. In the future, therapeutic modulation of this pathway might contribute to themanagement of fibrosis in CD.