FAM20A Mutations Can Cause Enamel-Renal Syndrome (ERS)

Wang, Shih‐Kai; Aref, Parissa; Hu, Yuanyuan; Milkovich, Rachel N.; Simmer, James P.; El-Khateeb, Mohammad; Daggag, Hinda; Baqain, Zaid H.; Hu, Jan C.‐C.

doi:10.1371/journal.pgen.1003302

Cited by 87 publications

(94 citation statements)

References 47 publications

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“…The proband of Family 3, who was untested at the time of our previous publication (Wang et al, 2013a), eventually underwent kidney ultrasound analysis and tested positive for nephrocalcinosis at Fig. 6).…”

Section: Discussionmentioning

confidence: 99%

FAM20A Mutations Associated with Enamel Renal Syndrome

et al. 2013

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We identified two families with an autosomal-recessive disorder manifested by severe enamel hypoplasia, delayed and failed tooth eruption, misshapen teeth, intrapulpal calcifications, and localized gingival hyperplasia. Genetic analyses identified novel FAM20A mutations associated with the disease phenotype in both families. The proband of Family 1 had an altered splice junction in Intron 1 (g.502011G>C; c.405-1G>C) and a missense mutation in Exon 8 (g.65094G>A; c.1207G>A; p.D403N). The missense mutation is notable because D403 is strictly conserved among FAM20A homologues, and the corresponding defect in FAM20C caused osteosclerotic bone dysplasia and a loss of kinase activity. The proband at age 12 yrs tested negative for nephrocalcinosis. The proband and her affected father in Family 2 were homozygous for a single nucleotide deletion that altered a splice junction in Intron 10 (g.66622del; c.1361+4del). Minigene analyses demonstrated that this alteration precluded normal splicing. Immunohistochemistry (IHC) of mouse maxillary first molars localized FAM20A in secretory-stage ameloblasts, in odontoblasts, and in the eruption pathway. IHC of kidneys localized FAM20A in the renal tubules. We conclude that FAM20A is likely a secretory pathway kinase and that loss-of-function mutations cause pathology where its phosphorylations are necessary for normal development or homeostasis.

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Section: Discussionmentioning

confidence: 99%

FAM20A Mutations Associated with Enamel Renal Syndrome

et al. 2013

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“…Fam20A, a paralog of Fam20C, is a pseudokinase that binds Fam20C and stimulates its kinase activity (15). Consequently, loss-of-function mutations in FAM20A cause enamel renal syndrome and amelogenesis imperfecta in humans (16,17). Fam20B is a proteoglycan kinase that phosphorylates the 2-hydroxyl of a xylose residue within the tetrasaccharide linkage region of proteoglycans (7).…”

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confidence: 99%

Phosphorylation of spore coat proteins by a family of atypical protein kinases

Nguyen

Sreelatha

Durrant

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The modification of proteins by phosphorylation occurs in all life forms and is catalyzed by a large superfamily of enzymes known as protein kinases. We recently discovered a family of secretory pathway kinases that phosphorylate extracellular proteins. One member, family with sequence similarity 20C (Fam20C), is the physiological Golgi casein kinase. While examining distantly related protein sequences, we observed low levels of identity between the spore coat protein H (CotH), and the Fam20C-related secretory pathway kinases. CotH is a component of the spore in many bacterial and eukaryotic species, and is required for efficient germination of spores in Bacillus subtilis; however, the mechanism by which CotH affects germination is unclear. Here, we show that CotH is a protein kinase. The crystal structure of CotH reveals an atypical protein kinase-like fold with a unique mode of ATP binding. Examination of the genes neighboring cotH in B. subtilis led us to identify two spore coat proteins, CotB and CotG, as CotH substrates. Furthermore, we show that CotH-dependent phosphorylation of CotB and CotG is required for the efficient germination of B. subtilis spores. Collectively, our results define a family of atypical protein kinases and reveal an unexpected role for protein phosphorylation in spore biology.

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“…Genetic deletion of Fam20B in mice results in embryonic lethality at E13.5, and mutations in Danio rerio result in reduced cartilage matrix production and skeletal defects (19,25). The substrates for Fam20A are unknown; however, mutations in FAM20A are known to cause amelogenesis imperfecta (AI) and enamel renal syndrome (ERS) in humans (26)(27)(28)(29). AI is a clinically and genetically heterogeneous group of disorders characterized by improper formation of enamel, a highly mineralized tissue comprising the outer surface of the vertebrate tooth (30).…”

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confidence: 99%

Crystal structure of the Golgi casein kinase

Xiao

Tagliabracci

Wen

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The family with sequence similarity 20 (Fam20) kinases phosphorylate extracellular substrates and play important roles in biomineralization. Fam20C is the Golgi casein kinase that phosphorylates secretory pathway proteins within Ser-x-Glu/pSer motifs. Mutations in Fam20C cause Raine syndrome, an osteosclerotic bone dysplasia. Here we report the crystal structure of the Fam20C ortholog from Caenorhabditis elegans. The nucleotide-free and Mn/ ADP-bound structures unveil an atypical protein kinase-like fold and highlight residues critical for activity. The position of the regulatory αC helix and the lack of an activation loop indicate an architecture primed for efficient catalysis. Furthermore, several distinct elements, including the presence of disulfide bonds, suggest that the Fam20 family diverged early in the evolution of the protein kinase superfamily. Our results reinforce the structural diversity of protein kinases and have important implications for patients with disorders of biomineralization.P rotein phosphorylation is a fundamental mechanism that regulates numerous physiological processes (1, 2). Protein kinases have evolved to function as dynamic switches relaying signals in response to various stimuli by transferring a phosphate from ATP to target proteins (3-5). Most phosphoproteins are found within the cell, residing in the nuclei and cytosol; however, secreted proteins, including casein and other members of the secretory calciumbinding phosphoprotein family, are phosphorylated as well (6). We recently identified a family of kinases that reside in the secretory pathway and function to phosphorylate extracellular substrates (7,8). One member of this family, Fam20C (family with sequence similarity 20, member C), is the physiological casein kinase that phosphorylates multiple secreted proteins within a Ser-x-Glu/pSer motif (7, 9, 10). The importance of this discovery is underscored by the fact that some 75% of the phosphoproteins identified in human serum and cerebrospinal fluid contain phosphate within this motif (11-13). Furthermore, mutations in FAM20C cause Raine syndrome, a deadly osteosclerotic bone dysplasia characterized by generalized osteosclerosis, ectopic calcifications, and characteristic facial features (14-16). Most individuals with Raine syndrome die within a few weeks after birth; however, nonlethal cases with dental abnormalities and clinical features of hypophosphatemia have been reported (17,18). Loss of Fam20C in mice also results in severe bone and tooth anomalies, as well as hypophosphatemia (19)(20)(21).Two other closely related Fam20C paralogs, Fam20A and Fam20B, are present in humans (22). Fam20B is ubiquitously expressed and phosphorylates xylose within the tetrasaccharide linkage region of proteoglycans (23). This phosphorylation event may influence glycosaminoglycan biosynthesis (24). Genetic deletion of Fam20B in mice results in embryonic lethality at E13.5, and mutations in Danio rerio result in reduced cartilage matrix production and skeletal defects (19,25). The substra...

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FAM20A Mutations Can Cause Enamel-Renal Syndrome (ERS)

Cited by 87 publications

References 47 publications

FAM20A Mutations Associated with Enamel Renal Syndrome

FAM20A Mutations Associated with Enamel Renal Syndrome

Phosphorylation of spore coat proteins by a family of atypical protein kinases

Crystal structure of the Golgi casein kinase

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