Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, 39011, Spain.
Commun Biol. 2020 Jun 5;3(1):283. doi: 10.1038/s42003-020-1012-3.
Digits shape is sculpted by interdigital programmed cell death during limb development. Here, we show that DNA breakage in the periphery of 5-methylcytosine nuclei foci of interdigital precursors precedes cell death. These cells showed higher genome instability than the digit-forming precursors when exposed to X-ray irradiation or local bone morphogenetic protein (BMP) treatments. Regional but not global DNA methylation differences were found between both progenitors. DNA-Methyl-Transferases (DNMTs) including DNMT1, DNMT3B and, to a lesser extent, DNMT3A, exhibited well-defined expression patterns in regions destined to degenerate, as the interdigital tissue and the prospective joint regions. Dnmt3b functional experiments revealed an inverse regulation of cell death and cartilage differentiation, by transcriptional regulation of key genes including Sox9, Scleraxis, p21 and Bak1, via differential methylation of CpG islands across their promoters. Our findings point to a regulation of cell death versus chondrogenesis of limb skeletal precursors based on epigenetic mechanisms.
在肢体发育过程中，指（趾）间的程序性细胞死亡会塑造指（趾）的形状。在这里，我们发现指间前体细胞中 5-甲基胞嘧啶核小体焦点周围的 DNA 断裂先于细胞死亡。与形成指（趾）的前体细胞相比，这些细胞在暴露于 X 射线照射或局部骨形态发生蛋白（BMP）处理时表现出更高的基因组不稳定性。在这两种前体细胞之间发现了区域而非整体 DNA 甲基化差异。包括 DNMT1、DNMT3B 在内的 DNA-甲基转移酶（DNMTs），以及在较小程度上的 DNMT3A，在指间组织和潜在的关节区域等注定要退化的区域表现出明确的表达模式。Dnmt3b 功能实验通过 Sox9、Scleraxis、p21 和 Bak1 等关键基因的转录调控，揭示了细胞死亡与软骨分化之间的反向调节，这是通过启动子上 CpG 岛的差异甲基化实现的。我们的研究结果表明，基于表观遗传机制，对肢体骨骼前体细胞的细胞死亡与软骨生成进行了调控。
