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tRNA methyltransferase homolog gene TRMT10A mutation in young onset diabetes and primary microcephaly in humans.

Igoillo-Esteve M, Genin A, Lambert N, Désir J, Pirson I, Abdulkarim B, Simonis N, Drielsma A, Marselli L, Marchetti P, Vanderhaeghen P, Eizirik DL, Wuyts W, Julier C, Chakera AJ, Ellard S, Hattersley AT, Abramowicz M, Cnop M - PLoS Genet. (2013)

Bottom Line: TRMT10A silencing induces rat and human β-cell apoptosis.Taken together, we propose that TRMT10A deficiency negatively affects β-cell mass and the pool of neurons in the developing brain.In light of the recent report that the type 2 diabetes candidate gene CDKAL1 is a tRNA methylthiotransferase, the findings in this family suggest broader relevance of tRNA methyltransferases in the pathogenesis of type 2 diabetes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Experimental Medicine, Université Libre de Bruxelles, Brussels, Belgium.

ABSTRACT
We describe a new syndrome of young onset diabetes, short stature and microcephaly with intellectual disability in a large consanguineous family with three affected children. Linkage analysis and whole exome sequencing were used to identify the causal nonsense mutation, which changed an arginine codon into a stop at position 127 of the tRNA methyltransferase homolog gene TRMT10A (also called RG9MTD2). TRMT10A mRNA and protein were absent in lymphoblasts from the affected siblings. TRMT10A is ubiquitously expressed but enriched in brain and pancreatic islets, consistent with the tissues affected in this syndrome. In situ hybridization studies showed that TRMT10A is expressed in human embryonic and fetal brain. TRMT10A is the mammalian ortholog of S. cerevisiae TRM10, previously shown to catalyze the methylation of guanine 9 (m(1)G9) in several tRNAs. Consistent with this putative function, in silico topology prediction indicated that TRMT10A has predominant nuclear localization, which we experimentally confirmed by immunofluorescence and confocal microscopy. TRMT10A localizes to the nucleolus of β- and non-β-cells, where tRNA modifications occur. TRMT10A silencing induces rat and human β-cell apoptosis. Taken together, we propose that TRMT10A deficiency negatively affects β-cell mass and the pool of neurons in the developing brain. This is the first study describing the impact of TRMT10A deficiency in mammals, highlighting a role in the pathogenesis of microcephaly and early onset diabetes. In light of the recent report that the type 2 diabetes candidate gene CDKAL1 is a tRNA methylthiotransferase, the findings in this family suggest broader relevance of tRNA methyltransferases in the pathogenesis of type 2 diabetes.

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Patients are homozygous for a nonsense mutation in TRMT10A and lose TRMT10A expression.(A) Sanger sequencing at the level of the mutation identified by whole exome sequencing in proband. The mutation c.379 G>A; p.Arg127Stop changes a CGA codon (Arginine) into a TGA codon (Stop), and is found homozygous in the proband (P), heterozygous in unaffected mother (M) and absent in an unrelated control subject (C). (B) TRMT10A protein and (C) mRNA expression was examined by Western blot and real-time PCR in lymphoblast from three controls (CT1-3), two patients homozygous for the nonsense mutation (P1 and P2) and one heterozygous carrier (HET). α-Tubulin was used as loading control and TRMT10A mRNA expression was normalized to the geometric mean of the reference genes GAPDH, actin and OAZ1 expression.
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pgen-1003888-g002: Patients are homozygous for a nonsense mutation in TRMT10A and lose TRMT10A expression.(A) Sanger sequencing at the level of the mutation identified by whole exome sequencing in proband. The mutation c.379 G>A; p.Arg127Stop changes a CGA codon (Arginine) into a TGA codon (Stop), and is found homozygous in the proband (P), heterozygous in unaffected mother (M) and absent in an unrelated control subject (C). (B) TRMT10A protein and (C) mRNA expression was examined by Western blot and real-time PCR in lymphoblast from three controls (CT1-3), two patients homozygous for the nonsense mutation (P1 and P2) and one heterozygous carrier (HET). α-Tubulin was used as loading control and TRMT10A mRNA expression was normalized to the geometric mean of the reference genes GAPDH, actin and OAZ1 expression.

Mentions: Exonic sequences-enriched DNA (whole exome) sequencing was performed in one proband and results were analyzed for variants that were not found in: dbSNP135 database, the Thousand Genomes database, the Exome Variant Server, or in-house exome sequencing on 51 individuals. There was only a single candidate mutation in the 3.1 Mb critical linkage segment, a homozygous G to A transition in exon 4 of gene TRMT10A (tRNA methyltransferase 10 homolog A (S. cerevisiae) at position 379 of the coding DNA sequence, predicted to replace an Arginine residue with a premature termination codon at position 127 of the polypeptide (c.379 G>A; p.Arg127Stop). Sanger sequencing confirmed the mutation (Figure 2A), which was homozygous in the three affected patients and heterozygous in both parents as well as in the unaffected brother with the critical recombination event. A comparison across species shows that Arg127 and the surrounding region are highly conserved (Figure S2). Outside the linkage region, exome analysis in the proband identified biallelic, potentially damaging mutations in the six following genes: BCLAF1; CES1; EVC2; PTPN22; ST13; ZNF626. As none were concordant in the three affected siblings, we rejected them as candidate mutations.


tRNA methyltransferase homolog gene TRMT10A mutation in young onset diabetes and primary microcephaly in humans.

Igoillo-Esteve M, Genin A, Lambert N, Désir J, Pirson I, Abdulkarim B, Simonis N, Drielsma A, Marselli L, Marchetti P, Vanderhaeghen P, Eizirik DL, Wuyts W, Julier C, Chakera AJ, Ellard S, Hattersley AT, Abramowicz M, Cnop M - PLoS Genet. (2013)

Patients are homozygous for a nonsense mutation in TRMT10A and lose TRMT10A expression.(A) Sanger sequencing at the level of the mutation identified by whole exome sequencing in proband. The mutation c.379 G>A; p.Arg127Stop changes a CGA codon (Arginine) into a TGA codon (Stop), and is found homozygous in the proband (P), heterozygous in unaffected mother (M) and absent in an unrelated control subject (C). (B) TRMT10A protein and (C) mRNA expression was examined by Western blot and real-time PCR in lymphoblast from three controls (CT1-3), two patients homozygous for the nonsense mutation (P1 and P2) and one heterozygous carrier (HET). α-Tubulin was used as loading control and TRMT10A mRNA expression was normalized to the geometric mean of the reference genes GAPDH, actin and OAZ1 expression.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814312&req=5

pgen-1003888-g002: Patients are homozygous for a nonsense mutation in TRMT10A and lose TRMT10A expression.(A) Sanger sequencing at the level of the mutation identified by whole exome sequencing in proband. The mutation c.379 G>A; p.Arg127Stop changes a CGA codon (Arginine) into a TGA codon (Stop), and is found homozygous in the proband (P), heterozygous in unaffected mother (M) and absent in an unrelated control subject (C). (B) TRMT10A protein and (C) mRNA expression was examined by Western blot and real-time PCR in lymphoblast from three controls (CT1-3), two patients homozygous for the nonsense mutation (P1 and P2) and one heterozygous carrier (HET). α-Tubulin was used as loading control and TRMT10A mRNA expression was normalized to the geometric mean of the reference genes GAPDH, actin and OAZ1 expression.
Mentions: Exonic sequences-enriched DNA (whole exome) sequencing was performed in one proband and results were analyzed for variants that were not found in: dbSNP135 database, the Thousand Genomes database, the Exome Variant Server, or in-house exome sequencing on 51 individuals. There was only a single candidate mutation in the 3.1 Mb critical linkage segment, a homozygous G to A transition in exon 4 of gene TRMT10A (tRNA methyltransferase 10 homolog A (S. cerevisiae) at position 379 of the coding DNA sequence, predicted to replace an Arginine residue with a premature termination codon at position 127 of the polypeptide (c.379 G>A; p.Arg127Stop). Sanger sequencing confirmed the mutation (Figure 2A), which was homozygous in the three affected patients and heterozygous in both parents as well as in the unaffected brother with the critical recombination event. A comparison across species shows that Arg127 and the surrounding region are highly conserved (Figure S2). Outside the linkage region, exome analysis in the proband identified biallelic, potentially damaging mutations in the six following genes: BCLAF1; CES1; EVC2; PTPN22; ST13; ZNF626. As none were concordant in the three affected siblings, we rejected them as candidate mutations.

Bottom Line: TRMT10A silencing induces rat and human β-cell apoptosis.Taken together, we propose that TRMT10A deficiency negatively affects β-cell mass and the pool of neurons in the developing brain.In light of the recent report that the type 2 diabetes candidate gene CDKAL1 is a tRNA methylthiotransferase, the findings in this family suggest broader relevance of tRNA methyltransferases in the pathogenesis of type 2 diabetes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Experimental Medicine, Université Libre de Bruxelles, Brussels, Belgium.

ABSTRACT
We describe a new syndrome of young onset diabetes, short stature and microcephaly with intellectual disability in a large consanguineous family with three affected children. Linkage analysis and whole exome sequencing were used to identify the causal nonsense mutation, which changed an arginine codon into a stop at position 127 of the tRNA methyltransferase homolog gene TRMT10A (also called RG9MTD2). TRMT10A mRNA and protein were absent in lymphoblasts from the affected siblings. TRMT10A is ubiquitously expressed but enriched in brain and pancreatic islets, consistent with the tissues affected in this syndrome. In situ hybridization studies showed that TRMT10A is expressed in human embryonic and fetal brain. TRMT10A is the mammalian ortholog of S. cerevisiae TRM10, previously shown to catalyze the methylation of guanine 9 (m(1)G9) in several tRNAs. Consistent with this putative function, in silico topology prediction indicated that TRMT10A has predominant nuclear localization, which we experimentally confirmed by immunofluorescence and confocal microscopy. TRMT10A localizes to the nucleolus of β- and non-β-cells, where tRNA modifications occur. TRMT10A silencing induces rat and human β-cell apoptosis. Taken together, we propose that TRMT10A deficiency negatively affects β-cell mass and the pool of neurons in the developing brain. This is the first study describing the impact of TRMT10A deficiency in mammals, highlighting a role in the pathogenesis of microcephaly and early onset diabetes. In light of the recent report that the type 2 diabetes candidate gene CDKAL1 is a tRNA methylthiotransferase, the findings in this family suggest broader relevance of tRNA methyltransferases in the pathogenesis of type 2 diabetes.

Show MeSH
Related in: MedlinePlus