GCK-MODY diabetes as a protein misfolding disease: The mutation R275C promotes protein misfolding, self-association and cellular degradation

MOLECULAR AND CELLULAR ENDOCRINOLOGY

卷:382

Article

Negahdar, Maria^1,2  Aukrust, Ingvild^1,2,3,4  Molnes, Janne^1,3,5  Solheim, Marie H.^1,2,3  Johansson, Bente B.^1,2,5  Sagen, Jorn V.^1,6,7  Dahl-Jorgensen, Knut^8,9  Kulkarni, Rohit N.⁴  Sovik, Oddmund¹  Flatmark, Torgeir³  Njolstad, Pal R.^1,5  Bjorkhaug, Lise^1,2,3 

[1] Univ Bergen, Dept Clin Sci, KG Jebsen Ctr Diabet Res, Bergen, Norway

[2] Haukeland Hosp, Ctr Med Genet & Mol Med, N-5021 Bergen, Norway

[3] Univ Bergen, Dept Biomed, Bergen, Norway

[4] Harvard Univ, Brigham & Womens Hosp, Sect Islet Cell Biol & Regenerat Med, Joslin Diabet Ctr,Med Sch, Boston, MA 02115 USA

[5] Haukeland Hosp, Dept Pediat, N-5021 Bergen, Norway

[6] Univ Bergen, Inst Med, Bergen, Norway

[7] Haukeland Hosp, Hormone Lab, N-5021 Bergen, Norway

[8] Oslo Univ Hosp, Pediat Dept Ullevaal, Oslo, Norway

[9] Univ Oslo, Fac Med, Oslo, Norway

关键词: Aggregation;    Catalytic activity;    Cellular protein degradation;    GCK-MODY diabetes;    Protein misfolding;    Self-association;   

DOI  :  10.1016/j.mce.2013.08.020

来源: Elsevier

【 摘 要 】

GCK-MODY, dominantly inherited mild hyperglycemia, is associated with more than 600 mutations in the glucokinase gene. Different molecular mechanisms have been shown to explain GCK-MODY. Here, we report a Pakistani family harboring the glucokinase mutation c.823C > T (p.R275C). The recombinant and in cellulo expressed mutant pancreatic enzyme revealed slightly increased enzyme activity (kat) and normal affinity for ct-D-glucose, and resistance to limited proteolysis by trypsin comparable with wildtype. When stably expressed in HEK293 cells and MIN6 13-cells (at different levels), the mutant protein appeared misfolded and unstable with a propensity to form dimers and aggregates. Its degradation rate was increased, involving the lysosomal and proteasomal quality control systems. On mutation, a hydrogen bond between the R275 side-chain and the carbonyl oxygen of D267 is broken, destabilizing the F260-L271 loop structure and the protein. This promotes the formation of dimers/aggregates and suggests that an increased cellular degradation is the molecular mechanism by which R275C causes GCK-MODY. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

【 授权许可】

Free