Cell Biology, Stem Cells, and Developmental Biology Graduate Program. University of Colorado Anschutz School of Medicine, Aurora, CO, USA, 80045; Department of Molecular, Cellular, and Developmental Biology. University of Colorado Boulder, Boulder, CO, USA, 80309.
Department of Craniofacial Biology, University of Colorado Anschutz School of Dentistry, Aurora, CO, USA, 80045.
Dev Biol. 2020 Aug 1;464(1):24-34. doi: 10.1016/j.ydbio.2020.05.006. Epub 2020 May 22.
Development of the craniofacial structures requires the precise differentiation of cranial neural crest cells into osteoblasts or chondrocytes. Here, we explore the epigenetic and non-epigenetic mechanisms that are required for the development of craniofacial chondrocytes. We previously demonstrated that the acetyltransferase activity of the highly conserved acetyltransferase GCN5, or KAT2A, is required for murine craniofacial development. We show that Gcn5 is required cell autonomously in the cranial neural crest. Moreover, GCN5 is required for chondrocyte development following the arrival of the cranial neural crest within the pharyngeal arches. Using a combination of in vivo and in vitro inhibition of GCN5 acetyltransferase activity, we demonstrate that GCN5 is a potent activator of chondrocyte maturation, acting to control chondrocyte maturation and size increase during pre-hypertrophic maturation to hypertrophic chondrocytes. Rather than acting as an epigenetic regulator of histone H3K9 acetylation, our findings suggest GCN5 primarily acts as a non-histone acetyltransferase to regulate chondrocyte development. Here, we investigate the contribution of GCN5 acetylation to the activity of the mTORC1 pathway. Our findings indicate that GCN5 acetylation is required for activation of this pathway, either via direct activation of mTORC1 or through indirect mechanisms. We also investigate one possibility of how mTORC1 activity is regulated through RAPTOR acetylation, which is hypothesized to enhance mTORC1 downstream phosphorylation. This study contributes to our understanding of the specificity of acetyltransferases, and the cell type specific roles in which these enzymes function.
颅面结构的发育需要颅神经嵴细胞精确地分化为成骨细胞或软骨细胞。在这里，我们探讨了颅面软骨细胞发育所必需的表观遗传和非表观遗传机制。我们之前证明了高度保守的乙酰转移酶 GCN5（或 KAT2A）的乙酰转移酶活性对于鼠类颅面发育是必需的。我们显示 Gcn5 在颅神经嵴中具有细胞自主的作用。此外，在颅神经嵴到达咽弓内后，GCN5 对于软骨细胞的发育也是必需的。通过体内和体外抑制 GCN5 乙酰转移酶活性的联合使用，我们证明 GCN5 是软骨细胞成熟的有效激活剂，能够控制软骨细胞在预肥大成熟为肥大软骨细胞过程中的成熟和大小增加。我们的研究结果表明，GCN5 主要作为一种非组蛋白乙酰转移酶来调节软骨细胞的发育，而不是作为组蛋白 H3K9 乙酰化的表观遗传调节剂。在这里，我们研究了 GCN5 乙酰化对 mTORC1 途径活性的贡献。我们的发现表明，GCN5 乙酰化对于该途径的激活是必需的，无论是通过直接激活 mTORC1 还是通过间接机制。我们还研究了一种通过 RAPTOR 乙酰化来调节 mTORC1 活性的可能性，这被假设为增强 mTORC1 下游磷酸化。这项研究有助于我们理解乙酰转移酶的特异性，以及这些酶在特定细胞类型中发挥的作用。
