A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase.
A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase.
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DOI：
10.1016/j.bbagen.2016.08.021
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发表时间：
2017-01
影响因子：
3
通讯作者：
Piercy, R. J.
中科院分区：
文献类型：
--
作者：
Maile, C. A.;Hingst, J. R.;Mahalingan, K. K.;O'Reilly, A. O.;Cleasby, M. E.;Mickelson, J. R.;McCue, M. E.;Anderson, S. M.;Hurley, T. D.;Wojtaszewski, J. F. P.;Piercy, R. J.
马1型多糖沉积性肌病（PSSM 1）与糖原合酶（GYS 1）基因中的错义突变（R309 H）、增强的糖原合酶（GS）活性以及肌肉中过多的糖原和支链淀粉内含物相关。马肌肉生化和重组酶动力学试验在体外和同源模拟，被用来调查的假设，即较高的GS活性在受影响的马肌肉是由较高的GS表达，失调，或通过构象变化组成型激活。PSSM 1影响的马肌肉有显着较高的糖原含量比对照马肌肉，尽管GS表达没有差异。GS活性显着高于纯合子突变体的肌肉比杂合子和对照马，在不存在和存在的变构调节剂，葡萄糖6磷酸（G6 P）。与对照组相比，纯合子突变马肌肉中2+2a位点的GS磷酸化水平显著增加，AMPKα1（一种上游激酶）表达显著升高，这可能反映了降低GS酶活性的生理学尝试。重组突变GS是高度活跃的，与一个相当低的Km UDP-葡萄糖，在G6 P的存在和不存在下，当与野生型GS相比，尽管它的磷酸化。突变酶的活性升高与通过磷酸化的无效调节相关，从而使其具有组成型活性。模型表明，突变破坏了通常稳定基础状态的盐桥，将平衡转移到酶的活性状态。这项研究解释了这种高度流行的葡聚糖肌病的功能发病机制的获得。
Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower Km for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation. Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state. This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.
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影响因子：
3
作者：
Jensen, Jorgen;Lai, Yu-Chiang
通讯作者：
Lai, Yu-Chiang
影响因子：
4.4
作者：
McCue, Molly E.;Valberg, Stephanie J.;Mickelson, James R.
通讯作者：
Mickelson, James R.
影响因子：
7.7
作者：
Jorgensen, SB;Nielsen, JN;Wojtaszewski, JFP
通讯作者：
Wojtaszewski, JFP
影响因子：
56.9
作者：
Lohi, H;Young, EJ;Minassian, BA
通讯作者：
Minassian, BA
影响因子：
14.9
作者：
Landau M;Mayrose I;Rosenberg Y;Glaser F;Martz E;Pupko T;Ben-Tal N
通讯作者：
Ben-Tal N