Genomics methodologies have significantly improved elucidation of Mendelian disorders. The combination with high-throughput functional-omics technologies potentiates the identification and confirmation of causative genetic variants, especially in singleton families of recessive inheritance. In a cohort of 99 individuals with abnormal Golgi glycosylation, 47 of which being unsolved, glycomics profiling was performed of total plasma glycoproteins. Combination with whole-exome sequencing in 31 cases revealed a known genetic defect in 15 individuals. To identify additional genetic factors, hierarchical clustering of the plasma glycomics data was done, which indicated a subgroup of four patients that shared a unique glycomics signature of hybrid type N-glycans. In two siblings, compound heterozygous mutations were found in SLC10A7, a gene of unknown function in human. These included a missense mutation that disrupted transmembrane domain 4 and a mutation in a splice acceptor site resulting in skipping of exon 9. The two other individuals showed a complete loss of SLC10A7 mRNA. The patients' phenotype consisted of amelogenesis imperfecta, skeletal dysplasia, and decreased bone mineral density compatible with osteoporosis. The patients' phenotype was mirrored in SLC10A7 deficient zebrafish. Furthermore, alizarin red staining of calcium deposits in zebrafish morphants showed a strong reduction in bone mineralization. Cell biology studies in fibroblasts of affected individuals showed intracellular mislocalization of glycoproteins and a defect in post-Golgi transport of glycoproteins to the cell membrane. In contrast to yeast, human SLC10A7 localized to the Golgi. Our combined data indicate an important role for SLC10A7 in bone mineralization and transport of glycoproteins to the extracellular matrix.

• MeSH
• dánio pruhované genetika   růst a vývoj   metabolismus   MeSH
• dospělí MeSH
• exom MeSH
• fenotyp MeSH
• fibroblasty metabolismus   patologie   MeSH
• fyziologická kalcifikace * MeSH
• genomika * MeSH
• glykomika * MeSH
• glykopeptidasa nedostatek   MeSH
• glykosylace MeSH
• Golgiho aparát metabolismus   patologie   MeSH
• kohortové studie MeSH
• kojenec MeSH
• kultivované buňky MeSH
• lidé MeSH
• mladý dospělý MeSH
• mutace * MeSH
• přenašeče organických aniontů závislé na sodíku genetika   metabolismus   MeSH
• rodokmen MeSH
• symportéry genetika   metabolismus   MeSH
• transport proteinů MeSH
• vrozené poruchy glykosylace komplikace   MeSH
• vývojové onemocnění kostí etiologie   metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• kojenec MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The formation of glycoconjugates depends on nucleotide sugars, which serve as donor substrates for glycosyltransferases in the lumen of Golgi vesicles and the endoplasmic reticulum (ER). Import of nucleotide sugars from the cytosol is an important prerequisite for these reactions and is mediated by nucleotide sugar transporters. Here, we report the identification of REPRESSOR OF CYTOKININ DEFICIENCY 1 (ROCK1, At5g65000) as an ER-localized facilitator of UDP-N-acetylglucosamine (UDP-GlcNAc) and UDP-N-acetylgalactosamine (UDP-GalNAc) transport in Arabidopsis thaliana. Mutant alleles of ROCK1 suppress phenotypes inferred by a reduced concentration of the plant hormone cytokinin. This suppression is caused by the loss of activity of cytokinin-degrading enzymes, cytokinin oxidases/dehydrogenases (CKXs). Cytokinin plays an essential role in regulating shoot apical meristem (SAM) activity and shoot architecture. We show that rock1 enhances SAM activity and organ formation rate, demonstrating an important role of ROCK1 in regulating the cytokinin signal in the meristematic cells through modulating activity of CKX proteins. Intriguingly, genetic and molecular analysis indicated that N-glycosylation of CKX1 was not affected by the lack of ROCK1-mediated supply of UDP-GlcNAc. In contrast, we show that CKX1 stability is regulated in a proteasome-dependent manner and that ROCK1 regulates the CKX1 level. The increased unfolded protein response in rock1 plants and suppression of phenotypes caused by the defective brassinosteroid receptor bri1-9 strongly suggest that the ROCK1 activity is an important part of the ER quality control system, which determines the fate of aberrant proteins in the secretory pathway.

• MeSH
• Arabidopsis metabolismus   ultrastruktura   MeSH
• biologický transport MeSH
• cytokininy metabolismus   MeSH
• endoplazmatické retikulum metabolismus   MeSH
• fenotyp MeSH
• meristém metabolismus   ultrastruktura   MeSH
• proteiny huseníčku metabolismus   MeSH
• transportní proteiny metabolismus   MeSH
• uridindifosfát-N-acetylgalaktosamin metabolismus   MeSH
• uridindifosfát-N-acetylglukosamin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH