The new role of chromatin protein hmgb2 on adipogenesis and rotator cuff rupture

5 THE NEW ROLE OF CHROMATIN PROTEIN HMGB2 ON ADIPOGENESIS AND ROTATOR CUFF RUPTURE Noboru Taniguchi, Hiroaki Yano, Yasuyuki Ishida, Naoki Suenaga, Etsuo Chosa, Department of Orthopaedic Surgery, Miyazaki University, Hokushin Orthopaedic Hospital Fatty degeneration is observed in the ruptured rotator cuff, but the responsible genes for this mechanism are unknown.We have reported that chromatin protein HMGB2 is highly expressed in mesenchymal stem cells (MSC) and is involved in chondrogenesis. In this study we sought to clarify the possible role of HMGB2 on adipogenesis. We established bone marrow-derived MSC from wildtype and Hmgb2-/mice and found that Hmgb2-/MSC did not differentiate to adipocyte by oil-red staining and real-time PCR. DNAmicroarray analysis showed that adipogenesis related genes such as Pparg, Ppargc1a, Fabp4, and Lpl were apparently decreased in Hmgb2-/MSC. HMGB2 was augmented during early adipogenic differentiation of 3T3L1 cells, and this differentiation was attenuated by gene knockdown for Hmgb2. These results suggest a new role of HMGB2on adipogenesis that might regulate fatty degeneration in a ruptured rotator cuff.