Katoku-Kikyo Nobuko, Kawakami Hiroko, Cantor Max, Kawakami Yasuhiko, Kikyo Nobuaki
Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA.
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA.
Nat Commun. 2025 Apr 30;16(1):4072. doi: 10.1038/s41467-025-59346-5.
mA RNA methylation is essential for many aspects of mammalian development but its roles in chondrogenesis remain largely unknown. Here, we show that mA is necessary for chondrogenesis and limb morphogenesis using limb progenitor-specific knockout mice of Mettl14, an essential subunit in the mA methyltransferase complex. The knockout disrupts cartilage anlagen formation in limb buds with 11 downregulated proteins known to dysregulate chondrogenesis and shorten limb skeletons upon mutation in mice and humans. Further studies show a gene regulatory hierarchy among the 11 proteins. mA stabilizes the transcript and increases the protein level of GDF5, a BMP family member. This activates the chondrogenic transcription factor genes Runx2 and Runx3, whose mRNAs are also stabilized by mA. They promote the transcription of six collagen genes and two other chondrogenic genes, Ddrgk1 and Pbxip1. Thus, this study uncovers an mA-based cascade essential for chondrogenesis during limb skeletal development.
N6-甲基腺苷（m6A）RNA甲基化对哺乳动物发育的多个方面至关重要，但其在软骨形成中的作用仍 largely未知。在此，我们利用Mettl14（m6A甲基转移酶复合体中的一个必需亚基）的肢体祖细胞特异性敲除小鼠，表明m6A对软骨形成和肢体形态发生是必需的。敲除破坏了肢芽中软骨原基的形成，有11种下调的蛋白质，已知这些蛋白质在小鼠和人类发生突变时会失调软骨形成并缩短肢体骨骼。进一步研究显示了这11种蛋白质之间的基因调控层次。m6A稳定转录本并增加骨形态发生蛋白（BMP）家族成员生长分化因子5（GDF5）的蛋白质水平。这激活了软骨形成转录因子基因Runx2和Runx3，其mRNA也由m6A稳定。它们促进六个胶原蛋白基因以及另外两个软骨形成基因Ddrgk1和Pbxip1的转录。因此，本研究揭示了一个基于m6A的级联反应，对肢体骨骼发育过程中的软骨形成至关重要。
