Previous studies have shown the essential roles of O-GlcNAc transferase (Ogt) and O-GlcNAcylation in neuronal development, function and neurologic diseases. However, the function of Ogt and O-GlcNAcylation in the adult cerebellum has not been well elucidated. Here, we have found that cerebellum has the highest level of O-GlcNAcylation relative to cortex and hippocampus of adult male mice. Specific deletion of Ogt in granule neuron precursors (GNPs) induces abnormal morphology and decreased size of the cerebellum in adult male Ogt deficient [conditional knock-out (cKO)] mice. Adult male cKO mice show the reduced density and aberrant distribution of cerebellar granule cells (CGCs), the disrupted arrangement of Bergman glia (BG) and Purkinje cells. In addition, adult male cKO mice exhibit aberrant synaptic connection, impaired motor coordination, and learning and memory abilities. Mechanistically, we have identified G-protein subunit α12 (Gα12) is modified by Ogt-mediated O-GlcNAcylation. O-GlcNAcylation of Gα12 facilitates its binding to Rho guanine nucleotide exchange factor 12 (Arhgef12) and consequently activates RhoA/ROCK signaling. RhoA/ROCK pathway activator LPA can rescue the developmental deficits of Ogt deficient CGCs. Therefore, our study has revealed the critical function and related mechanisms of Ogt and O-GlcNAcylation in the cerebellum of adult male mice.

SIGNIFICANCE STATEMENT Cerebellar function are regulated by diverse mechanisms. To unveil novel mechanisms is critical for understanding the cerebellar function and the clinical therapy of cerebellum-related diseases. In the present study, we have shown that O-GlcNAc transferase gene (Ogt) deletion induces abnormal cerebellar morphology, synaptic connection, and behavioral deficits of adult male mice. Mechanistically, Ogt catalyzes O-GlcNAcylation of Gα12, which promotes the binding to Arhgef12, and regulates RhoA/ROCK signaling pathway. Our study has uncovered the important roles of Ogt and O-GlcNAcylation in regulating cerebellar function and cerebellum-related behavior. Our results suggest that Ogt and O-GlcNAcylation could be potential targets for some cerebellum-related diseases.

先前的研究表明 O-GlcNAc 转移酶 (Ogt) 和 O-GlcNAc 酰化在神经元发育、功能和神经系统疾病中的重要作用。然而，Ogt 和 O-GlcNAcNA 酰化在成人小脑中的功能尚未得到很好的阐明。在这里，我们发现相对于成年雄性小鼠的皮质和海马，小脑具有最高水平的 O-GlcNAcNAclation。颗粒神经元前体 (GNP) 中Ogt的特异性缺失会导致成年雄性Ogt缺陷 [条件敲除 (cKO)] 小鼠的小脑形态异常和尺寸减小。成年雄性 cKO 小鼠显示小脑颗粒细胞 (CGC) 密度降低和分布异常，伯格曼胶质细胞 (BG) 和浦肯野细胞排列紊乱。此外，成年雄性 cKO 小鼠表现出异常的突触连接、运动协调能力以及学习和记忆能力受损。从机制上讲，我们已经确定 G 蛋白亚基 α12 (Gα12) 是通过 Ogt 介导的 O-GlcNAcylation 进行修饰的。 Gα12 的 O-GlcNAc 酰化促进其与 Rho 鸟嘌呤核苷酸交换因子 12 (Arhgef12) 的结合，从而激活 RhoA/ROCK 信号传导。 RhoA/ROCK 通路激活剂 LPA 可以挽救Ogt缺陷 CGC 的发育缺陷。因此，我们的研究揭示了成年雄性小鼠小脑中Ogt和O-GlcNAcNA酰化的关键功能和相关机制。

意义陈述小脑功能受多种机制调节。揭示新机制对于了解小脑功能和小脑相关疾病的临床治疗至关重要。在本研究中，我们发现O-GlcNAc转移酶基因（ Ogt ）缺失会导致成年雄性小鼠的小脑形态、突触连接和行为缺陷异常。从机制上讲，Ogt 催化 Gα12 的 O-GlcNAc 酰化，促进与 Arhgef12 的结合，并调节 RhoA/ROCK 信号通路。我们的研究揭示了 Ogt 和 O-GlcNAcylation 在调节小脑功能和小脑相关行为中的重要作用。我们的结果表明 Ogt 和 O-GlcNAcNAc 化可能是一些小脑相关疾病的潜在靶点。