Muscle-specific lack of Gfpt1 triggers ER stress to alleviate misfolded protein accumulation.

IF 4 3区 医学 Q2 CELL BIOLOGY
Disease Models & Mechanisms Pub Date : 2024-08-01 Epub Date: 2024-07-25 DOI:10.1242/dmm.050768
Ruchen Zhang, Paniz Farshadyeganeh, Bisei Ohkawara, Kazuki Nakajima, Jun-Ichi Takeda, Mikako Ito, Shaochuan Zhang, Yuki Miyasaka, Tamio Ohno, Madoka Mori-Yoshimura, Akio Masuda, Kinji Ohno
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引用次数: 0

Abstract

Pathogenic variants in GFPT1, encoding a key enzyme to synthesize UDP-N-acetylglucosamine (UDP-GlcNAc), cause congenital myasthenic syndrome (CMS). We made a knock-in (KI) mouse model carrying a frameshift variant in Gfpt1 exon 9, simulating that found in a patient with CMS. As Gfpt1 exon 9 is exclusively expressed in striated muscles, Gfpt1-KI mice were deficient for Gfpt1 only in skeletal muscles. In Gfpt1-KI mice, (1) UDP-HexNAc, CMP-NeuAc and protein O-GlcNAcylation were reduced in skeletal muscles; (2) aged Gfpt1-KI mice showed poor exercise performance and abnormal neuromuscular junction structures; and (3) markers of the unfolded protein response (UPR) were elevated in skeletal muscles. Denervation-mediated enhancement of endoplasmic reticulum (ER) stress in Gfpt1-KI mice facilitated protein folding, ubiquitin-proteasome degradation and apoptosis, whereas autophagy was not induced and protein aggregates were markedly increased. Lack of autophagy was accounted for by enhanced degradation of FoxO1 by increased Xbp1-s/u proteins. Similarly, in Gfpt1-silenced C2C12 myotubes, ER stress exacerbated protein aggregates and activated apoptosis, but autophagy was attenuated. In both skeletal muscles in Gfpt1-KI mice and Gfpt1-silenced C2C12 myotubes, maladaptive UPR failed to eliminate protein aggregates and provoked apoptosis.

基因敲入小鼠肌肉特异性缺乏 GFPT1 会引发 ER 应激,从而缓解折叠错误的蛋白质。
编码合成 UDP-N-乙酰葡糖胺(UDP-GlcNAc)的关键酶 GFPT1 的致病变体会导致先天性肌无力综合征(CMS)。我们制作了一个基因敲入(KI)小鼠模型,该小鼠携带 Gfpt1 第 9 号外显子的框架移位变体,模拟 CMS 患者。由于 Gfpt1 第 9 外显子只包含在横纹肌中,因此 Gfpt1-KI 小鼠只在骨骼肌中缺乏 Gfpt1。在 Gfpt1-KI 小鼠中,(i) 骨骼肌中的 UDP-HexNAc、CMP-NeuAc 和蛋白质 O-GlcNAcylations 减少;(ii) 老龄 Gfpt1-KI 小鼠的运动表现较差,神经肌肉接头结构异常;(iii) 骨骼肌中的未折叠蛋白反应(UPR)标记升高。Gfpt1-KI 小鼠去神经介导的ER应激增强促进了蛋白质折叠、泛素-蛋白酶体降解和细胞凋亡,而自噬没有被诱导,蛋白质聚集明显增加。Xbp1-s/u蛋白增加导致的FoxO1降解增强是缺乏自噬的原因。同样,在被 Gfpt1 沉默的 C2C12 肌细胞管中,ER 应激加剧了蛋白质聚集并激活了细胞凋亡,但自噬作用却减弱了。在Gfpt1-KI小鼠的骨骼肌和Gfpt1沉默的C2C12肌细胞管中,不适应性UPR未能消除蛋白质聚集并引发细胞凋亡。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Disease Models & Mechanisms
Disease Models & Mechanisms 医学-病理学
CiteScore
6.60
自引率
7.00%
发文量
203
审稿时长
6-12 weeks
期刊介绍: Disease Models & Mechanisms (DMM) is an online Open Access journal focusing on the use of model systems to better understand, diagnose and treat human disease.
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