Heparan sulfate (HS) is an important component of the kidney anionic filtration barrier, the glomerular basement membrane (GBM). HS chains attached to proteoglycan protein cores are modified by sulfotransferases in a highly ordered series of biosynthetic steps resulting in immense structural diversity due to negatively charged sulfate modifications. 3--sulfation is the least abundant modification generated by a family of seven isoforms but creates the most highly sulfated HS domains. We analyzed the kidney phenotypes in the and -knockout (KO) mice, the isoforms enriched in kidney podocytes. Individual KO mice show no overt kidney phenotype, although kidneys were smaller than wildtype (WT). Furthermore, double knockout (DKO) kidneys were smaller but also had a reduction in glomerular size relative to wildtype (WT). Mass spectrometry analysis of kidney HS showed reduced 3--sulfation in and , but not in kidneys. Glomerular HS showed reduced HS staining and reduced ligand-and-carbohydrate engagement (LACE) assay, a tool that detects changes in binding of growth factor receptor-ligand complexes to HS. Interestingly, DKO mice have increased levels of blood urea nitrogen, although no differences were detected in urinary levels of albumin, creatinine and nephrin. Finally, transmission electron microscopy showed irregular and thickened GBM and podocyte foot process effacement in the DKO compared to WT. Together, our data suggest that loss of 3--HS domains disrupts the kidney glomerular architecture without affecting the glomerular filtration barrier and overall kidney function.

中文翻译：

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3-O-磺基转移酶 Hs3st3a1 和 Hs3st3b1 的损失会减小肾脏和肾小球的大小并破坏肾小球结构


硫酸乙酰肝素 (HS) 是肾脏阴离子滤过屏障、肾小球基底膜 (GBM) 的重要组成部分。附着在蛋白聚糖蛋白核心上的 HS 链在一系列高度有序的生物合成步骤中被磺基转移酶修饰，由于带负电荷的硫酸盐修饰而导致巨大的结构多样性。 3--硫酸化是七种亚型家族产生的最不丰富的修饰，但产生了最高硫酸化的 HS 结构域。我们分析了 和 敲除（KO）小鼠的肾脏表型，肾足细胞中富含亚型。尽管肾脏比野生型（WT）小，但个体 KO 小鼠没有表现出明显的肾脏表型。此外，与野生型（WT）相比，双敲除（DKO）肾脏更小，但肾小球尺寸也减小。肾脏 HS 的质谱分析显示 和 中的 3-硫酸化减少，但肾脏中没有。肾小球 HS 显示 HS 染色减少，配体与碳水化合物结合 (LACE) 测定减少，LACE 测定是一种检测生长因子受体-配体复合物与 HS 结合变化的工具。有趣的是，DKO 小鼠的血液尿素氮水平升高，但尿液中的白蛋白、肌酐和去氧肾上腺素水平没有检测到差异。最后，透射电子显微镜显示与 WT 相比，DKO 中 GBM 不规则且增厚，足细胞足突消失。总之，我们的数据表明，3--HS 结构域的丢失会破坏肾小球结构，但不会影响肾小球滤过屏障和整体肾功能。