线粒体动态变化对下颌下腺细胞内钙信号调控中的作用及机制研究

Mitochondria are the main organelles for ATP generation through oxidative phosphorylation and calcium storage in mammalian cells. Maintenance of mitochondrial homeostasis is essential for cell survival and function. The applicant found mitochondria was localized under the plasma membrane and close to the nuclei in the submandibular gland, and mitochondrial hyperfusin was accompanied with decreased Ca2+mobilization in NOD mice. But the exact function of mitochondria in submandibular gland need to be further studied. Based on the preliminary data, we hypothesized that inflammatory cytokine may cause mitochondria hyperfusin and impair through downregulate dynamin like protein 1(DRP1). We plan to investigate the effects of mitochondrial dynamics on regulating the Ca2+mobilization and the secretion of submandibular gland in mice. We will focus on the Ca2+mobilization, mitochondrial dynamics and DRP1. The corresponding signal transduction pathway will also be investigated in this project. The results of this research will propose a theory that mitochondrial dynamics plays a role in the regulation of submandibular gland, which can expand the knowledge about the regulatory mechanism of secretion and provide a new target for improving the secretion of submandibular gland.

线粒体是细胞能量代谢中心和钙储存器，功能正常与否决定细胞的功能及存亡。我们的预实验显示舍格伦模型NOD小鼠线粒体分裂蛋白（DRP1）减少，线粒体高度聚合且细胞内Ca2+信号降低，提出炎症因子可能通过抑制DRP1的表达引起线粒体高度聚合，进而影响线粒体功能及Ca2+信号的科学假说。我们拟在NOD模型观察DRP1表达与线粒体功能及Ca2+信号的变化，明确线粒体动态变化对Ca2+及细胞功能的调节；在培养的下颌下腺细胞敲低或过表达DRP1，明确DRP1改变及其对线粒体功能及Ca2+的影响；TNF-α处理对DRP1表达的影响，明确NOD小鼠DRP1下调及线粒体高度聚合的分子机制。上述研究将完善对下颌下腺中线粒体功能的认识，全面地揭示下颌下腺分泌的调控机制，也为揭示舍格伦综合症时下颌下腺功能低下的发病机制提供新的见解及治疗的新靶点。

线粒体是细胞能量代谢中心和Ca2+储存细胞器，功能正常与否决定细胞的功能及存亡。线粒体在唾液腺分泌中的作用目前尚未明确。本研究发现下颌下腺细胞中线粒体分布呈区域性，舍格伦模型NOD小鼠下颌下腺中线粒体高度聚合且调节线粒体分裂的分子DRP1表达下降，细胞内卡巴胆碱引起的Ca2+信号降低且分泌下降。培养的大鼠下颌下腺细胞SMG-C6，TNF-α刺激6小时后，DRP1表达出现明显下降，且细胞内卡巴胆碱引起的Ca2+信号降低，但线粒体内Ca2+信号增强；当细胞过表达DRP1分子后，可增强细胞内卡巴胆碱引起的Ca2+信号，降低线粒体内Ca2+信号。其机制与细胞内miR34a调控DRP1表达有关。本研究揭示细胞内线粒体动态影响腺泡细胞内Ca2+信号并进一步影响分泌功能，TNF-α可通过miR34a下调DRP1表达，减少线粒体分裂从而减弱细胞内Ca2+信号并进一步影响分泌功能。本研究明确线粒体动态变化在下颌下腺细胞分泌中的调节机制，丰富和完善下颌下腺分泌调节的理论。该研究将更加全面地揭示调控下颌下腺分泌的机制，也为涎腺功能低下的防治提供新的途径和靶点。