microRNA-29b knocks down collagen type I production in cultured rainbow trout (Oncorhynchus mykiss) cardiac fibroblasts

ABSTRACT Warm acclimation of rainbow trout can cause a decrease in the collagen content of the heart. This ability to remove cardiac collagen is particularly interesting considering that collagen deposition in the mammalian heart, following an injury, is permanent. We hypothesized that collagen removal can be facilitated by microRNA-29b (miR-29b), a highly conserved, small, non-coding RNA, as a reduction in this microRNA has been reported during the development of fibrosis in the mammalian heart. We also used a bioinformatics approach to investigate the binding potential of miR-29b to the seed sequences of vertebrate collagen isoforms. Cultured trout cardiac fibroblasts were transfected with zebrafish mature miR-29b mimic for 7 days with re-transfection occurring after 3 days. Transfection induced a 17.8-fold increase in miR-29b transcript abundance (P