Dysferlin is expressed in human placenta but does not associate with caveolin

A proteomics screen of human placental microvillous syncytiotrophoblasts (STBs) revealed the expression of dysferlin (DYSF), a plasma membrane repair protein associated with certain muscular dystrophies. This was unexpected given that previous studies of DYSF have been restricted to skeletal muscle. Within the placenta, DYSF localized to the STB and, with the exception of variable labeling in the fetal placental endothelium, none of the other cell types expressed detectable levels of DYSF. Such restricted expression was recapitulated using primary trophoblast cell cultures, because the syncytia expressed DYSF, but not the prefusion mononuclear cells. The apical plasma membrane of the STB contained approximately 4-fold more DYSF than the basal membrane, suggesting polarized trafficking. Unlike skeletal muscle, DYSF in the STB is localized to the plasma membrane in the absence of caveolin. DYSF expression in the STB was developmentally regulated, because first-trimester placentas expressed approximately 3-fold more DYSF than term placentas. As the current literature indicates that few cell types express DYSF, it is of interest that the two major syncytial structures in the human body, skeletal muscle and the STB, express this protein.