Missense variant in TPI1 (Arg189Gln) causes neurologic deficits through structural changes in the triosephosphate isomerase catalytic site and reduced enzyme levels in vivo

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1865

Article

Roland, Bartholomew P.^1,2,3  Richards, Kristen R.⁷  Hrizo, Stacy L.^1,2,8  Eicher, Samantha^1,2  Barile, Zackery J.^1,2  Chang, Tien-Chien^1,2  Savon, Grace^1,2  Bianchi, Paola⁴  Fermo, Elisa⁴  Ricerca, Bianca Maria⁵  Tortorolo, Luca⁶  Vockley, Jerry^9,10  VanDemark, Andrew P.⁷  Palladino, Michael J.^1,2 

[1] Univ Pittsburgh, Sch Med, Dept Pharmacol & Chem Biol, Pittsburgh, PA 15261 USA

[2] Univ Pittsburgh, Sch Med, PIND, Pittsburgh, PA 15261 USA

[3] Vanderbilt Univ, Dept Pharmacol, Nashville, TN 37232 USA

[4] Fdn IRCCS Ca Granda Osped Maggiore Policlin, UOC Ematol, UOS Fisiopatol Anemie, Via F Sforza 35, I-20122 Milan, Italy

[5] Univ Hosp A Gemelli, Inst Hematol, Largo A Gemelli 8, I-00168 Rome, Italy

[6] Univ Hosp A Gemelli, Pediat Intens Care Unit, Largo A Gemelli 8, I-00168 Rome, Italy

[7] Univ Pittsburgh, Biol Sci & Struct Biol, Pittsburgh, PA 15260 USA

[8] Slippery Rock Univ, Dept Biol, Slippery Rock, PA 16057 USA

[9] Univ Pittsburgh, Sch Med, Dept Pediat & Human Genet, Pittsburgh, PA 15261 USA

[10] Univ Pittsburgh, Sch Publ Hlth, Dept Pediat & Human Genet, Pittsburgh, PA 15261 USA

关键词: Triosephosphate isomerase;    TPI deficiency;    Glycolytic enzymopathy;    Genomic engineering;   

DOI  :  10.1016/j.bbadis.2019.05.002

来源: Elsevier

【 摘 要 】

Mutations in the gene triosephosphate isomerase (TPI) lead to a severe multisystem condition that is characterized by hemolytic anemia, a weakened immune system, and significant neurologic symptoms such as seizures, distal neuropathy, and intellectual disability. No effective therapy is available. Here we report a compound heterozygous patient with a novel TPI pathogenic variant (NM_000365.5:c.569G > A:p.(Arg189Gln)) in combination with the common (NM_000365.5:c.315G > C:p.(Glu104Asp)) allele. We characterized the novel variant by mutating the homologous Arg in Drosophila using a genomic engineering system, demonstrating that missense mutations at this position cause a strong loss of function. Compound heterozygote animals were generated and exhibit motor behavioural deficits and markedly reduced protein levels. Furthermore, examinations of the TPIArg189Gln/TPIGlu104Asp patient fibroblasts confirmed the reduction of TPI levels, suggesting that Arg189Gln may also affect the stability of the protein. The Arg189 residue participates in two salt bridges on the backside of the TPI enzyme dimer, and we reveal that a mutation at this position alters the coordination of the substrate-binding site and important catalytic residues. Collectively, these data reveal a new human pathogenic variant associated with TPI deficiency, identify the Arg189 salt bridge as critical for organizing the catalytic site of the TPI enzyme, and demonstrates that reduced TPI levels are associated with human TPI deficiency. These findings advance our understanding of the molecular pathogenesis of the disease, and suggest new therapeutic avenues for pre-clinical trials.

【 授权许可】

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