Kopp Johannes, Jahn Denise, Vogt Guido, Psoma Anthi, Ratto Edoardo, Morelle Willy, Stelzer Nina, Hausser Ingrid, Hoffmann Anne, de Los Santos Miguel Rodriguez, Koch Leonard A, Fischer-Zirnsak Björn, Thiel Christian, Palm Wilhelm, Meierhofer David, van den Bogaart Geert, Foulquier François, Meinhardt Andreas, Kornak Uwe
Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität Zu Berlin, Institute of Medical Genetics and Human Genetics, 13353, Berlin, Germany.
Max Planck Institute for Molecular Genetics, RG Development & Disease, 14195, Berlin, Germany.
Cell Mol Life Sci. 2024 Dec 16;82(1):4. doi: 10.1007/s00018-024-05506-7.
Loss-of-function variants in ATP6V0A2, encoding the trans Golgi V-ATPase subunit V0a2, cause wrinkly skin syndrome (WSS), a connective tissue disorder with glycosylation defects and aberrant cortical neuron migration. We used knock-out (Atp6v0a2) and knock-in (Atp6v0a2) mice harboring the R755Q missense mutation selectively abolishing V0a2-mediated proton transport to investigate the WSS pathomechanism. Homozygous mutants from both strains displayed a reduction of growth, dermis thickness, and elastic fiber formation compatible with WSS. A hitherto unrecognized male infertility due to globozoospermia was evident in both mouse lines with impaired Golgi-derived acrosome formation and abolished mucin-type O-glycosylation in spermatids. Atp6v0a2 mutants showed enhanced fucosylation and glycosaminoglycan modification, but reduced levels of glycanated decorin and sialylation in skin and/or fibroblasts, which were absent or milder in Atp6v0a2. Atp6v0a2 mutants displayed more abnormal migration of cortical neurons, correlating with seizures and a reduced O-mannosylation of α-dystroglycan. While anterograde transport within the secretory pathway was similarly delayed in both mutants the brefeldin A-induced retrograde fusion of Golgi membranes with the endoplasmic reticulum was less impaired in Atp6v0a2. Measurement of the pH in the trans Golgi compartment revealed a shift from 5.80 in wildtype to 6.52 in Atp6v0a2 and 6.25 in Atp6v0a2. Our findings suggest that altered O-glycosylation is more relevant for the WSS pathomechanism than N-glycosylation and leads to a secondary dystroglycanopathy. Most phenotypic and cellular properties correlate with the different degrees of trans Golgi pH elevation in both mutants underlining the fundamental relevance of pH regulation in the secretory pathway.
编码反式高尔基体V-ATP酶亚基V0a2的ATP6V0A2功能丧失变体导致皱纹皮肤综合征（WSS），这是一种伴有糖基化缺陷和皮质神经元迁移异常的结缔组织疾病。我们使用携带R755Q错义突变的基因敲除（Atp6v0a2）和基因敲入（Atp6v0a2）小鼠，该突变选择性地消除了V0a2介导的质子转运，以研究WSS的发病机制。两种品系的纯合突变体均表现出生长、真皮厚度和弹性纤维形成减少，与WSS相符。在这两种小鼠品系中，由于精子头异常导致的前所未有的男性不育明显，高尔基体衍生的顶体形成受损，精子细胞中的粘蛋白型O-糖基化缺失。Atp6v0a2突变体在皮肤和/或成纤维细胞中显示岩藻糖基化和糖胺聚糖修饰增强，但糖化核心蛋白聚糖和唾液酸化水平降低，在Atp6v0a2中不存在或较轻。Atp6v0a2突变体显示皮质神经元迁移异常更多，这与癫痫发作和α-肌营养不良聚糖的O-甘露糖基化减少相关。虽然在两个突变体中分泌途径内的顺向转运同样延迟，但布雷菲德菌素A诱导的高尔基体膜与内质网的逆向融合在Atp6v0a2中受损较小。反式高尔基体区室pH值的测量显示，从野生型的5.80转变为Atp6v0a2中的6.52和Atp6v0a2中的6.25。我们的研究结果表明，O-糖基化改变比N-糖基化与WSS发病机制更相关，并导致继发性肌营养不良聚糖病。大多数表型和细胞特性与两个突变体中反式高尔基体pH值升高的不同程度相关，强调了分泌途径中pH调节的基本相关性。
