Many intracellular proteins are modified by N-acetylglucosamine, a post-translational modification termed O-GlcNAc. This modification is found on serine and threonine side chains and has the potential to regulate signaling pathways through interplay with phosphorylation. Here, we discover and characterize one such example. We find that O-GlcNAc levels control the sensitivity of fibroblasts to actin contraction induced by the signaling lipid sphingosine-1-phosphate (S1P), culminating in the phosphorylation of myosin light chain (MLC) and cellular contraction. Specifically, O-GlcNAc modification of the phosphatase subunit MYPT1 inhibits this pathway by blocking MYPT1 phosphorylation, maintaining its activity and causing the dephosphorylation of MLC. Finally, we demonstrate that O-GlcNAc levels alter the sensitivity of primary human dermal fibroblasts in a collagen-matrix model of wound healing. Our findings have important implications for the role of O-GlcNAc in fibroblast motility and differentiation, particularly in diabetic wound healing.

许多细胞内蛋白质被N-乙酰氨基葡萄糖修饰，一种称为O - GlcNAc的翻译后修饰。这种修饰存在于丝氨酸和苏氨酸侧链上，有可能通过与磷酸化的相互作用来调节信号通路。在这里，我们发现并描述了一个这样的例子。我们发现O- GlcNAc 水平控制成纤维细胞对由信号脂质 1-磷酸鞘氨醇 (S1P) 诱导的肌动蛋白收缩的敏感性，最终导致肌球蛋白轻链 (MLC) 的磷酸化和细胞收缩。具体来说，O磷酸酶亚基 MYPT1 的 -GlcNAc 修饰通过阻断 MYPT1 磷酸化、维持其活性和导致 MLC 去磷酸化来抑制该途径。最后，我们证明了O- GlcNAc 水平改变了伤口愈合的胶原基质模型中原代人真皮成纤维细胞的敏感性。我们的发现对O- GlcNAc 在成纤维细胞运动和分化中的作用具有重要意义，特别是在糖尿病伤口愈合中。