褪黑素通过BMPs-Smad1/5/8信号通路调控间充质干细胞(MSCs)成软骨分化的机制研究

Melatonin (N-acetyl-5-methoxytrypta-mine), a neurohormone mainly synthesized and secreted by the pineal gland. Melatonin, is involved in a number of physiological processes. Our recent study (J Pineal Res, 2014) found that melatonin can enhance the chondrogenic differentiation of human bone marrow mesenchymal stem cells (MSCs), but the underlying mechanism is unknown. BMPs-Smad1/5/8 signaling pathway is known to play an critical role in regulating chondrogenesis. In our pre-experiments, we found that melatonin treatment can upregulate the expression of BMP2 and stimulate phosphorylation of Smad1/5/8 during the chondrogenic differentiation of human MSCs. Thus we proposed the hypothesis that melatonin may enhance chondrogenic differentiation of human MSCs via BMP-Smad1/5/8 signaling pathway. In this project, we plan to verify this hypothesis by conducting the following studies. Firstly, we will further prove that melatonin can activate BMPs-Smad1/5/8 signaling pathway. Then, we will try to identify that whether BMPs-Smad1/5/8 pathway is involved in the process of melatonin-enhanced chondrogenic differentiation of human MSCs. At last, we want to find out that through which signal transduction mechanism melatonin activates BMPs-Smad1/5/8 pathway. The goal of this project is to identify the mechanism of melatonin-enhanced MSCs chondrogenic differentiation, which can provide evidences for application of melatonin in tissue engineering of cartilage injury.

褪黑素作为一种内分泌激素在调控软骨代谢分化中发挥重要作用。我们研究发现褪黑素能够促进间充质干细胞(MSCs)成软骨分化(Gao W, J Pineal Res, 2014)，但具体机制尚不清楚。BMPs-Smad1/5/8信号通路是介导软骨分化发育的关键通路。我们前期预实验发现在MSCs成软骨分化中，褪黑素能够上调BMP2分子的表达、并增加Smad1/5/8的磷酸化水平，提示褪黑素能够激活该通路。因此，我们推测褪黑素可能是通过该通路调控MSCs的成软骨分化。为了探讨该科学问题，本项目拟开展以下研究:1.进一步明确在MSCs成软骨分化中，褪黑素能够激活BMPs-Smad1/5/8通路；2.探讨褪黑素是否通过该通路促进MSCs成软骨分化；3.对褪黑素如何激活该通路的信号转导机制进行研究。研究成果有望阐明褪黑素调控MSCs成软骨分化的机制，为将褪黑素应用于软骨损伤的干细胞组织工程等领域奠定基础

在国家自然科学基金资助下，项目负责人主要开展了以下工作：一、深入探讨褪黑素在局部炎症微环境下对间充质干细胞(mesenchymal stem cells, MSCs)成软骨分化的保护作用及相关机制。研究发现褪黑素能够通过减弱炎症介质IL-1β对NF-κB信号通路的活化而对其抑制MSCs成软骨分化的效应起到逆转保护作用 (Stem cell research & therapy, 2018, 共同第一作者, IF 4.627)，为将褪黑素应用于干细胞组织工程等领域奠定了理论基础。二、对青少年特发性脊柱侧凸(Adolescent idiopathic scoliosis, AIS)这一常见脊柱骨骼发育畸形疾病的发病机制进行研究。我们利用一个包括6名患者在内的11人AIS大家系，通过全基因组外显子测序及基因连锁分析定位出该家系中存在位于17号染色体MAPK7基因的异常突变。进一步，我们利用CRISPR/Cas9基因编辑技术构建mapk7基因特异性敲除的斑马鱼模型，发现突变体斑马鱼中轴骨出现了类似于AIS的侧方偏曲畸形，表明MAPK7基因突变确实是AIS的致病突变 (Human Mutation, 2017, 第一作者, IF=4.453)。三、对项目负责人本专业常见疾病临床诊疗的相关问题进行了研究，包括：1.总结了AIS患者脊椎椎弓根畸形发育规律(Clinical Orthopaedics and Related Research, 2017, 第二作者, IF=4.154)；2.探讨了氨甲环酸在减少颈椎后路手术术中出血的作用(Medicine, 2017, 共同第一作者, IF=1.87)；3.探讨了肠道菌群多样性分布对骨质疏松发生的影响 (PeerJ, 2017, 共同第一作者，IF=2.353)；4.对通过前路手术治疗下颈椎骨折脱位的疗效进行了总结分析(World Neurosurgery, 2018, 第一作者, IF=1.723)；5.分析了经短节段联合骨水泥强化治疗陈旧性骨质疏松骨折的疗效(BMC Musculoskeletal Disorders, 2019, 共同通讯作者, IF=2.002)；6.对微创经椎间孔入路腰椎椎间融合术治疗青少年双侧峡部裂型滑脱的疗效进行了分析(中国医师进修杂志, 2016, 通讯作者)。