剪切应力通过转录因子的乙酰化与去乙酰化影响成骨细胞增殖与分化功能的研究

To study the osteogenesis induced by mechanical factors is very important in the fields of mechanobiology and clinic.The effects of shear stress on the proliferation and differentiation of osteoblasts are its critical issue.It has been demonstrated that there exist same upstream signal for the proliferation and differentiation of osteoblasts induced by shear stress.So,we hypothesize that proliferation or differentiation of osteoblasts induced by shear stress would be dependent on the transcription factors as Runx2 and E2F.In the subject MC3T3 osteoblasts and primary osteoblasts from cranial bone of neonatal rat will be used.Moreover following protocols will be performed in order to demonstrate our hypothesis.1) to study the effects of shear stress on the proliferation and differentiation of osteoblasts in different cell cycle stages;2) To study Runx2 and E2F and their acetylation and deacetylation;3) to find the relationship between the results from above protocols;4) to study the effects of acetylation and deacetylation of Runx2 and E2F on proliferation and differntiation of osteoblasts stimulated with shear stress by related inhibitors.Anymore,we will also study the changes of proliferation and differentiation of osteoblasts stimulated by HDAC inhibitors and shear stress,and then to confirm the signal pathway and find some of reasonable way to prevent from bone loss induced by HDAC inhibitors.

力的成骨生物学效应研究有重要的理论与临床价值，剪切应力如何影响成骨细胞的增殖与分化功能是该领域的关键科学问题。已有的研究表明，剪切应力影响成骨细胞增殖与分化的上游信号途径是一致的，因此我们认为，剪切应力刺激成骨细胞后究竟发生增殖还是分化的关键在于转录因子。本课题拟以MC3T3成骨细胞、新生鼠颅骨成骨细胞为对象，通过研究剪切应力对不同细胞周期阶段增殖与分化功能的影响，及其与Runx2、E2F等转录因子在不同细胞周期阶段的存在状态以及乙酰化、去乙酰化程度之间的关系，并使用转录因子乙酰化的激动剂、抑制剂等手段，寻找剪切应力通过转录因子乙酰化与去乙酰化影响成骨细胞增殖与分化的信号通路，最后，本课题还将研究去乙酰化酶抑制剂与剪切应力共同刺激成骨细胞对其增殖与分化功能的影响，进一步验证该信号通路，并为去乙酰化酶诱导骨量减少寻找合适的预防方法。

流体剪切应力是影响成骨细胞增殖、分化的功能因子。已有的报告指出，剪切应力既可以增加成骨细胞的增殖，也能促进成骨细胞的分化。本课题围绕成骨细胞如何分别影响其增殖与分化，以剪切应力诱导的细胞内钙瞬态为核心，结合细胞因子、转录因子、组蛋白乙酰化等系统地进行了研究，取得了以下结果：.1、.G0/G1期，剪切应力促进了成骨细胞的分化，抑制了其增殖；对细胞分化的影响与Runx2、P21表达相关，由ERK与MAPK2共同促进；对细胞增殖的影响与P21、pRB有关，主要通过ERK途径。.2、.建立了剪切应力诱导的细胞内钙瞬态数学模型，阐明了剪切应力诱导细胞内钙瞬态产生的过程，并进一步阐明了成骨细胞剪切应力不应期产生的机理。.3、.研究发现，细胞内钙瞬态幅度是影响细胞增殖与分化的关键，提高剪切应力诱导的细胞内钙瞬态幅度，能够存进剪切应力诱导的细胞的增殖；不同细胞形态对增值的影响研究表明，内质网IP3R、SERCA表达与内置网钙容量决定了细胞内钙瞬态的特征，进而影响了细胞的增殖。.4、.组蛋白的乙酰化酶活性影响成骨细胞的增殖与分化，HDAC8的表达和分化相关，而HDAC1、HDAC2和HDAC8的表达与增殖相关。.5、.基于本课题共毕业博士生4名，硕士生2名，还有在研2名博士与2名硕士参与了该课题；本课题的结果已发表SCI收录文章9篇，国内会议文章2篇，还有4篇文章在写作中。