Thyroid-Stimulating Hormone Receptor Expression on Primary Cultured Human Extraocular Muscle Myoblasts ChoiHee-Young JeonHyeShin YangJae Wook AhnJeong Hyo JungJae Ho 2018 <p>To isolate and culture human extraocular muscle (EOM) myoblasts and facilitate their differentiation to myotubes <i>in vitro</i>, and to determine whether these myoblasts express thyroid-stimulating hormone receptor (TSHR).</p> <p>Human EOM myoblasts were isolated from EOM samples, and identified by immunostaining for PAX7 and MYOD1 (markers of human skeletal myoblasts), and western blot for desmin (muscle marker). In addition, we investigated the expressions of <i>SHOX2</i> (a genetic marker of EOM myoblasts) and <i>HOXC10</i> (an exclusive marker of hind-limb muscle-derived myoblasts) by RT-PCR. Fusion index and myotube area were measured to quantify myotube differentiation. TSHR immunostaining and western blot were used to determine the presence of TSHR on human EOM myoblasts and investigate its expression during myogenesis.</p> <p>Human EOM myoblasts were immunopositive for PAX7 and MYOD1 staining, and had desmin expression during myogenesis. The EOM-specific gene <i>SHOX2</i> was detected by RT-PCR, but <i>HOXC10</i> was not detected. The significant change in both fusion index and myotubes were shown at 8 days after induction of differentiation myotubes. Immunostaining revealed TSHR was expressed on human EOM myoblasts and western blot demonstrated the presence of TSHR protein and highest TSHR protein expression was shown at 10 days after myogenic differentiation.</p> <p>Human EOM myoblasts were cultured and underwent myogenic differentiation <i>in vitro</i>. TSHR protein was detected on human EOM myoblasts and increasing TSHR expression during myogenic differentiation.</p>