Differentiation-dependent PTPIP51 Expression in Human Skeletal Muscle Cell Culture

Abstract

S U M M A R Y Protein tyrosine phosphatase-interacting protein 51 (PTPIP51) expression was analyzed in proliferating and differentiating human myogenic cells cultured in vitro. Satellite cell cultures derived from four different individuals were used in this study. To analyze the expression of PTPIP51, myoblasts were cultured under conditions promoting either proliferation or differentiation. In addition, further differentiation of already-differentiated myobtubes was inhibited by resubmitting the cells to conditions promoting proliferation. PTPIP51 protein and mRNA were investigated in samples taken at defined time intervals by immunostaining, immunoblotting, in situ hybridization, and PCR. Image analyses of fluorescence immunostainings were used to quantify PTPIP51 in cultured myoblasts and myotubes. Myoblasts grown in the presence of epidermal and fibroblast growth factors (EGF and FGF), both promoting proliferation, expressed PTPIP51 on a basic level. Differentiation to multinuclear myotubes displayed a linear increase in PTPIP51 expression. The rise in PTPIP51 protein was paralleled by an augmented expression of muscle-specific proteins, namely, sarcoplasmic reticulum Ca 21 ATPase and myosin heavy-chain protein, both linked to a progressive state of myotubal differentiation. This differentiation-induced increase in PTPIP51 was partly reversible by resubmission of differentiated myotubes to conditions boosting proliferation. The results clearly point toward a strong association between PTPIP51 expression and differentiation in human muscle cells. (J Histochem Cytochem 57:425-435, 2009)

Interaction of PTPIP51 with Tubulin, CGI-99 and Nuf2 During Cell Cycle Progression

“…The antibody binds to the EGFP fusion PTPIP51 protein expressed in HEK293 [ 19 ]. Preabsorbing the PTPIP51 antibody against its antigen completely abolished the immune reaction in all tested samples [ 20 , 21 , 22 ].…”

Crosstalks of the PTPIP51 interactome revealed in Her2 amplified breast cancer cells by the novel small molecule LDC3/Dynarrestin

“…Physiologically, PTPIP51 exhibits a heterogeneous panel of functions. PTPIP51 is involved in apoptosis, development, differentiation, cell elongation, migration and NFκB signaling [15–19]. Noteworthy, PTPIP51 as well interacts with VAPB in order to regulate the calcium homeostasis and formation of mitochondria-associated endoplasmic reticulum membranes (MAM) [20,21].…”

Protein tyrosine phosphatase interacting protein 51—a jack-of-all-trades protein

“…Undifferentiated myoblasts show both low mRNA and protein levels of PTPIP51. Differentiation into multinucleated myotubes results in a linear increase of PTPIP51 protein levels proceeded by an intense increase of PTPIP51 mRNA expression (Barop et al 2009). UpORF repression of translation is unlikely.…”

“…As shown by various studies, the PTPIP51 protein is associated with proliferation, differentiation and apoptosis (Barop et al 2009;Koch et al 2008;Lv et al 2006). To date, the protein structure of PTPIP51 is unclear.…”