C6ORF32, AN HDAC6-BINDING PROTEIN THAT REGULATES MYOBLAST DIFFERENTIATION

描述（由申请方提供）：骨骼肌由成肌细胞融合形成的多核合胞体组成。通过微阵列研究，发现当肌管含有2-5个肌核时，C6 ORF 32的表达在人成肌细胞融合的早期上调（Cerletti等人，2006年）。C6 ORF 32表达的下调由于成肌蛋白表达的显著降低而导致成肌细胞融合的阻断（Yoon等人，2007年）。通过计算分析，预测的C6 ORF 32蛋白只包含一个已知功能的结构域，一个假定的HDAC结合结构域。发现C6 ORF 32与HDAC 6结合，HDAC 6是一种IIb类HDAC，已知其在促进细胞运动性中的功能。假设HDAC 6和C6 ORF 32在功能上是连接的，并且HDAC 6和C6 ORF 32之间的相互作用通过降低HDAC 6的去乙酰化活性来正向调节肌源性分化。本研究将在体外和体内研究HDAC 6和C6 ORF 32在骨骼肌中的调控关系，具体目的如下：1）确定C6 ORF 32与HDAC 6的关键结合区域，并证明这两种蛋白在体内发生结合; 2）确定HDAC 6是否通过调节C6 ORF 32乙酰化/去乙酰化来调节成肌细胞分化; 3）评估C6 ORF 32是否通过调节HDAC 6活性来调节成肌细胞分化; 4）确定体内C6 ORF 32表达的消除是否通过影响HDAC 6功能而导致肌肉发育、功能和再生的缺陷。这些研究将为了解未来靶向C6 ORF 32和HDAC 6之间的调节相互作用的药物治疗是否适合增强肌源性修复奠定基础。

DESCRIPTION (provided by applicant): Skeletal muscle is comprised of multinucleated syncytia formed by the fusion of myoblasts. Through microarray studies, it was found that expression of C6ORF32 is upregulated early during human myoblast fusion, when myotubes contain between 2-5 myonuclei (Cerletti et al., 2006). Downregulation of C6ORF32 expression causes a block in myoblast fusion due to a significant decrease in myogenin expression (Yoon et al., 2007). By computational analyses, the predicted C6ORF32 protein contains only one domain of known function, a putative HDAC-binding domain. It was found that C6ORF32 binds to HDAC6, a class IIb HDAC known for its function in promoting cell motility. It is hypothesized that HDAC6 and C6ORF32 are functionally connected, and the interaction between HDAC6 and C6ORF32 positively regulates myogenic differentiation by reducing the de-acetylation activity of HDAC6. The regulatory connection between HDAC6 and C6ORF32 in skeletal muscle will be studied both in vitro and in vivo via the following specific aims: 1) Define the critical binding region of C6ORF32 to HDAC6, and demonstrate that binding of these two proteins occurs in vivo; 2) Determine if HDAC6 regulates myoblast differentiation by modulating C6ORF32 acetylation/de-acetylation; 3) Evaluate if C6ORF32 regulates myoblast differentiation by modulating HDAC6 activity; 4) Determine if ablation of C6ORF32 expression in vivo yields to defects in muscle development, function and regeneration by affecting HDAC6 function. These studies will constitute the groundwork for understanding whether future pharmacological therapies targeting the regulatory interaction between C6ORF32 and HDAC6 are amenable to enhance myogenic repair.