Durin Zoé, Layotte Aurore, Morelle Willy, Houdou Marine, Folcher Antoine, Legrand Dominique, Lefeber Dirk, Prevarskaya Natalia, Von Blume Julia, Cormier-Daire Valérie, Foulquier François
Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale Et Fonctionnelle, 59000, Lille, France.
Inserm U1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, Equipe Labellisée Par La Ligue Nationale Contre Le Cancer, GIS ONCO Lille, University of Lille, Lille, France.
Cell Mol Life Sci. 2025 Jan 8;82(1):40. doi: 10.1007/s00018-024-05551-2.
Glycans are known to be fundamental for many cellular and physiological functions. Congenital disorders of glycosylation (CDG) currently encompassing over 160 subtypes, are characterized by glycan synthesis and/or processing defects. Despite the increasing number of CDG patients, therapeutic options remain very limited as our knowledge on glycan synthesis is fragmented. The emergence of CDG resulting from defects in ER/ Golgi homeostasis makes this even more difficult. SLC10A7 belongs to the SLC10 protein family, known as bile acid and steroid transport family, exhibiting a unique structure. It shows a ubiquitous expression and is linked to negative calcium regulation in cells. The mechanisms by which SLC10A7 deficiency leads to Golgi glycosylation abnormalities are unknown. The present study identifies major O-glycosylation defects in both SLC10A7 KO HAP1 cells and SLC10A7-CDG patient fibroblasts and reveals an increased ER and Golgi calcium contents. We also show that the abundance of COSMC and C1GALT1 is altered in SLC10A7-CDG patient cells, as well as the subcellular Golgi localization of the Ca-binding Cab45 protein. Finally, we demonstrate that supraphysiological manganese supplementation suppresses the deficient electrophoretic mobility of TGN46 by an aberrant transfer of GalNAc residues, and reveal COSMC Mn sensitivity. These findings provide novel insights into the mechanisms of Golgi glycosylation defects in SLC10A7-deficient cells. They show that SLC10A7 is a key Golgi transmembrane protein maintaining the tight regulation of Ca homeostasis in the ER and Golgi compartments, both essential for glycosylation.
已知聚糖对许多细胞和生理功能至关重要。目前，先天性糖基化障碍（CDG）包含160多种亚型，其特征是聚糖合成和/或加工缺陷。尽管CDG患者数量不断增加，但由于我们对聚糖合成的了解零散，治疗选择仍然非常有限。内质网/高尔基体稳态缺陷导致的CDG的出现使这一情况更加困难。SLC10A7属于SLC10蛋白家族，即胆汁酸和类固醇转运家族，具有独特的结构。它在全身广泛表达，并与细胞内的负钙调节有关。SLC10A7缺乏导致高尔基体糖基化异常的机制尚不清楚。本研究确定了SLC10A7基因敲除的HAP1细胞和SLC10A7-CDG患者成纤维细胞中主要的O-糖基化缺陷，并揭示了内质网和高尔基体钙含量增加。我们还表明，COSMC和C1GALT1的丰度在SLC10A7-CDG患者细胞中发生改变，以及钙结合蛋白Cab45在高尔基体的亚细胞定位也发生改变。最后，我们证明超生理剂量的锰补充通过异常转移N-乙酰半乳糖胺残基抑制了TGN46的电泳迁移率不足，并揭示了COSMC对锰的敏感性。这些发现为SLC10A7缺陷细胞中高尔基体糖基化缺陷的机制提供了新的见解。它们表明，SLC10A7是一种关键的高尔基体跨膜蛋白，维持内质网和高尔基体区室中钙稳态的严格调节，而这两者对于糖基化都是必不可少的。
