Bedelbaeva Kamila, Cameron Benjamin, Latella John, Aslanukov Azamat, Gourevitch Dmitri, Davuluri Ramana, Heber-Katz Ellen
Lankenau Institute for Medical Research (LIMR), Wynnewood, PA, United States.
The Wistar Institute, Philadelphia, PA, United States.
Front Cell Dev Biol. 2023 Oct 26;11:1101480. doi: 10.3389/fcell.2023.1101480. eCollection 2023.
The MRL mouse strain is one of the few examples of a mammal capable of healing appendage wounds by regeneration, a process that begins with the formation of a blastema, a structure containing de-differentiating mesenchymal cells. HIF-1α expression in the nascent MRL wound site blastema is one of the earliest identified events and is sufficient to initiate the complete regenerative program. However, HIF-1α regulates many cellular processes modulating the expression of hundreds of genes. A later signal event is the absence of a functional G1 checkpoint, leading to G2 cell cycle arrest with increased cellular DNA but little cell division observed in the blastema. This lack of mitosis in MRL blastema cells is also a hallmark of regeneration in classical invertebrate and vertebrate regenerators such as planaria, hydra, and newt. Here, we explore the cellular events occurring between HIF-1α upregulation and its regulation of the genes involved in G2 arrest (, , , and ), and identify epithelial-mesenchymal transition (EMT) (Twist and Slug) and chromatin remodeling (EZH-2 and H3K27me3) as key intermediary processes. The locus of these cellular events is highly regionalized within the blastema, occurring in the same cells as determined by double staining by immunohistochemistry and FACS analysis, and appears as EMT and chromatin remodeling, followed by G2 arrest determined by kinetic expression studies.
MRL小鼠品系是少数能够通过再生愈合附肢伤口的哺乳动物例子之一，这一过程始于芽基的形成，芽基是一种包含去分化间充质细胞的结构。新生MRL伤口部位芽基中的HIF-1α表达是最早被确定的事件之一，并且足以启动完整的再生程序。然而，HIF-1α调节许多细胞过程，调控数百个基因的表达。随后的一个信号事件是缺乏功能性的G1检查点，导致G2期细胞周期停滞，芽基中细胞DNA增加，但细胞分裂很少。MRL芽基细胞中这种有丝分裂的缺乏也是经典无脊椎动物和脊椎动物再生者（如涡虫、水螅和蝾螈）再生的一个标志。在这里，我们探讨了HIF-1α上调与其对参与G2期停滞的基因（、、和）的调控之间发生的细胞事件，并确定上皮-间充质转化（EMT）（Twist和Slug）和染色质重塑（EZH-2和H3K27me3）是关键的中间过程。这些细胞事件的发生位点在芽基内高度区域化，通过免疫组织化学和FACS分析的双重染色确定发生在相同的细胞中，并且表现为EMT和染色质重塑，随后通过动力学表达研究确定为G2期停滞。
