ABSTRACT

TECPR2 (tectonin beta-propeller repeat containing 2) is a large, multi-domain protein comprised of an amino-terminal WD domain, a middle unstructured region and a carboxy-terminal TEPCR domain comprises of six TECPR repeats followed by a functional LIR motif. Human TECPR2 mutations are linked to spastic paraplegia type 49 (SPG49), a hereditary neurodegenerative disorder. Here we show that basal macroautophagic/autophagic flux is impaired in SPG49 patient fibroblasts in the form of accumulated autophagosomes. Ectopic expression of either full length TECPR2 or the TECPR domain rescued autophagy in patient fibroblasts in a LIR-dependent manner. Moreover, this domain is recruited to the cytosolic leaflet of autophagosomal and lysosomal membranes in a LIR- and VAMP8-dependent manner, respectively. These findings provide evidence for a new role of the TECPR domain in particular, and TECPR2 in general, in lysosomal targeting of autophagosomes via association with Atg8-family proteins on autophagosomes and VAMP8 on lysosomes.

Abbreviations: HOPS: homotypic fusion and vacuole protein sorting; LIR: LC3-interacting region; SPG49: spastic paraplegia type 49; STX17: syntaxin 17; TECPR2: tectonin beta-propeller repeat containing 2; VAMP8: vesicle associated membrane protein 8

摘要

TECPR2（含有 2 个构造素 β-螺旋桨重复序列）是一种大型多域蛋白质，由氨基末端 WD 结构域、中间非结构化区域和羧基末端 TEPCR 结构域组成，由六个 TECPR 重复序列和一个功能性 LIR 基序组成。人类TECPR2突变与 49 型痉挛性截瘫（SPG49）有关，这是一种遗传性神经退行性疾病。在这里，我们显示 SPG49 患者成纤维细胞中的基础巨自噬/自噬通量以积累的自噬体的形式受损。全长 TECPR2 或 TECPR 结构域的异位表达以 LIR 依赖性方式挽救了患者成纤维细胞中的自噬。此外，该结构域分别以 LIR 和 VAMP8 依赖性方式被募集到自噬体和溶酶体膜的胞质小叶中。这些发现为 TECPR 结构域特别是 TECPR2 在溶酶体靶向自噬体中通过与自噬体上的 Atg8 家族蛋白和溶酶体上的 VAMP8 结合而发挥新作用提供了证据。

缩写： HOPS：同型融合和液泡蛋白分选；LIR：LC3相互作用区；SPG49：痉挛性截瘫49型；STX17：语法 17；TECPR2：含有 2 个 tectonin β-螺旋桨重复；VAMP8：囊泡相关膜蛋白 8