自噬受体NBR1介导微管骨架动态重组调控破骨细胞分化的研究

The most recent study has indicated that selective autophagy might play essential roles in the process of cell differentiation. Our current study, for the first time, found that selective autophagy was activated during osteoclastogenesis, while suppression of this pathway could significantly attenuate the differentiation of osteoclasts. In addition, our undertaken study also revealed that during osteoclastogenesis the accumulation of an autophagic receptor NBR1 expression was closely associated with the dynamic reorganization of microtubule network, and involved in the formation of F-Actin ring. The present project is designed to investigate and elucidate: (1) the relationship among NBR1 expression, microtubule reorganization and osteoclast differentiation within osteolytic diseases; (2) the role of NBR1-dependent selective autophagy in osteoclast differentiation; (3) the role and underlying mechanism of NBR1 in the regulation of dynamic reorganization of microtubule network during osteoclastogenesi. Our research may further unmask the mechanisms underlying osteoclast differentiation within the osteolytic diseases(such as osteoporosis and osteoarthritis),and more importantly provide a novel insight into drug development for treating these diseases.

最新研究表明自噬的选择性活化在细胞分化过程中可能起重要调控作用。本课题组前期研究首次在破骨细胞分化过程中检测到选择性自噬的活化，而阻断该途径可显著抑制破骨细胞分化。此外，我们的近期研究还发现在破骨细胞分化过程中自噬受体NBR1的积聚与微管骨架的重组在定位上具有一致性，且与肌动蛋白环的形成具有高度相关性。本项目旨在进一步研究和明确：(1) 自噬受体NBR1在颌面部溶骨性疾病中的表达及其与微管骨架重组和破骨细胞分化的相关性；(2)NBR1依赖性自噬对破骨细胞分化的调控作用及分子机制；(3) NBR1调控破骨细胞分化过程中微管骨架动态重组的作用和具体分子机制。该项研究将有助于进一步加深对溶骨性疾病（骨质疏松症、骨关节炎等）发病机制的理解，为治疗该类疾病的新药开发提供新的思路。

近年来研究证实，自噬在破骨细胞分化过程中发挥重要作用。本项目研究过程中，我们运用免疫组织化学及荧光染色法证实在人牙源性角化囊性瘤组织中，自噬相关基因及蛋白较正常口腔粘膜组织表达升高，提示自噬在这种骨吸收性疾病中处于活化状态；运用荧光定量PCR和免疫组化研究证实上皮标志物E-cadherin表达水平较正常口腔粘膜和根尖囊肿显著下调，而间质细胞标志物 N-cadherin 表达水平较正常口腔粘膜和根尖囊肿相比上调。此外，部分牙源性角化囊性瘤上皮组织中共表达NBR1和E-cad，提示选择性自噬可能在介导牙源性角化囊性瘤上皮间质化中起重要作用。体外细胞实验证实：正常生理状态下sRANKL诱导的破骨细胞分化过程中，可检测到自噬受体p62的活化，而采用RNAi技术沉默自噬基因p62则影响破骨细胞分化过程中肌动蛋白环的形成。在此基础上，在牙源性角化囊性瘤组织标本中，我们还拓展研究了细胞间隙连接蛋白Cx43和Cx32表达下调与人牙源性角化囊性瘤上皮细胞自噬活化的相关性。此外，我们研究发现牙源性角化囊性瘤间质组织中微血管密度明显高于口腔正常黏膜组织，且异常增多的血管生成与病变的侵袭性及骨吸收密切相关。