HDAC2 双酶协同致修复细胞增殖和凋亡失衡在病理性瘢痕形成中的作用及分子机制研究

The disequilibrium between cellular proliferation and apoptosis plays an important role in the formation of pathologic scars.Unfortunately the mechanism of which remains unclear. The expression of HDAC2 is a dynamic process in normal wound healing, however, high and persistent at pathologic scars. The wound-healing was significantly slow in HDAC2 knock-out mice shown in our previous experiments. It suggested that HDAC2 plays a key role in regulating wound healing, but its mechanism requires elucidation. Previous studies have shown that HDAC2 is able to silent the expression of genes related to anti-proliferation and pro-apoptosis at the transcription level through the reaction of deacetylase. In addition, we found that, similar to SUMO E3 ligase, HDAC2 is able to up-regulate the sumolation of eIF4E, which in turn boosts the translation of genes related to pro-proliferation and anti-apoptosis and thus controls the balance between cellular proliferation and apoptosis. Here we propose that through the synergic action of dual enzyme, HDAC2 selectively suppresses transcription or promotes translation of cap-dependent mRNA, and thus regulates accordingly the expression of genes related to proliferation and apoptosis. Therefore, HDAC2 plays an important role in normal wound healing and formation of pathologic scars by regulating the balance/disqquilibrium between cellular proliferation and apoptosis. In order to test for this hypothesis, we will rescue the functional structure domain gene of HDAC2 to damaged skin in HDAC2-/- KO mice as well as its fibroblast cells, and specifically inhibit the expression or activities of HDAC2 in pig hyperplastic scar tissue and fibroblast cells from patients’ pathologic scars. This study is going to explore the synergic effect of HDAC2 dual enzyme on the formation of pathologic scars as well as its mechanism of action, finally aiming to provide novel insights and approaches to improve the treatment and prevention of pathologic scars by targeting HDAC2.

修复细胞增殖和凋亡失衡是病理性瘢痕形成之关键环节，但机制不清。预实验显示正常创面HDAC2呈动态表达，病理性瘢痕则持续高表达，且其敲出小鼠创面愈合速度减慢，提示其在创面修复调控中起重要作用，但机制不清。已知HDAC2可通过去乙酰化酶功能，在转录水平沉默抗增殖和促凋亡基因的表达。而我们发现，其兼有SUMO E3连接酶功能而促进eIF4E的SUMO化修饰，在翻译水平激活促增殖和抗凋亡基因的表达。由此提出“HDAC2通过双酶协同，致转录抑制和翻译激活，选择性调节细胞增殖和凋亡基因的表达，导致修复细胞增殖和凋亡失衡，在病理性瘢痕形成中发挥重要作用”的假设。为此，本研究拟通过结构域基因回补HDAC2敲出小鼠致伤皮肤和成纤维细胞，以及特异性抑制患者病理性瘢痕来源成纤维细胞和猪增生性瘢痕中HDAC2的表达或双酶活性，探讨其在病理性瘢痕形成中的作用和机制，为靶向阻断其双酶活性抗瘢痕策略的应用奠定基础。

组蛋白去乙酰化酶II(HDAC2)在创面愈合及瘢痕生成过程中的作用及机制目前并不清楚。我们通过实验研究发现正常创面愈合过程中，HDAC2在创面的表达呈先升后降的动态模式，而其在病理性瘢痕中呈持续性的高表达状态。此外，我们通过构建HDAC2敲除小鼠模型发现，HDAC2敲除小鼠创面愈合显著降低。这表明HDAC2对创面愈合是正向调控的作用。进一步地机制研究发现，HDAC2具有SUMO E3连接酶的功能，它可以促进翻译起始复合物eIF4E的SUMO-1修饰作用。另外，HDAC2具有的SUMO E3连接酶活性还可促进成纤维细胞中增殖与凋亡相关基因的表达。最后，在本次研究中我们还意外发现低浓度的DMSO具有促进皮肤创面愈合的功能，其作用机制是一方面，低浓度DMSO活化成纤维细胞中的PI3K/AKT信号通路，导致增殖相关基因的翻译而促进成纤维细胞增殖；另一方面，增殖的成纤维细胞通过分泌TGF-β促进角质形成细胞迁移。低浓度DMSO通过这两重作用共同促进皮肤创面愈合。我们的研究揭示了HDAC2在创面愈合及瘢痕生成中的作用及分子机制，意外发现低浓度的DMSO具有促进皮肤创面愈合的功能，加深了人们对创面愈合调控机理的认识，为治疗创面及瘢痕提供了新的思路。