Autophagy pathway upregulation in a human iPSC-derived neuronal model of Cohen syndrome with VPS13B missense mutations

You-Kyung Lee,Bong-Kiun Kaang,Ji-Hye Kwak,Soo-Kyeong Lee,Deok-Jin Jang,Jin-A Lee,Kyungmin Lee,Jae-Hyung Lee,Yang Hoon Huh,Suin Choi,Yong-Seok Lee,Chae-Seok Lim

doi:10.1186/s13041-020-00611-7

Abstract

Significant clinical symptoms of Cohen syndrome (CS), a rare autosomal recessive disorder, include intellectual disability, facial dysmorphism, postnatal microcephaly, retinal dystrophy, and intermittent neutropenia. CS has been associated with mutations in the VPS13B (vacuolar protein sorting 13 homolog B) gene, which regulates vesicle-mediated protein sorting and transport; however, the cellular mechanism underlying CS pathogenesis in patient-derived neurons remains uncertain. This report states that autophagic vacuoles accumulate in CS fibroblasts and the axonal terminals of CS patient-specific induced pluripotent stem cells (CS iPSC)-derived neurons; additionally, autophagic flux was significantly increased in CS-derived neurons compared to control neurons. VPS13B knockout HeLa cell lines generated using the CRISPR/Cas9 genome editing system showed significant upregulation of autophagic flux, indicating that VSP13B may be associated with autophagy in CS. Transcriptomic analysis focusing on the autophagy pathway revealed that genes associated with autophagosome organization were dysregulated in CS-derived neurons. ATG4C is a mammalian ATG4 paralog and a crucial regulatory component of the autophagosome biogenesis/recycling pathway. ATG4C was significantly upregulated in CS-derived neurons, indicating that autophagy is upregulated in CS neurons. The autophagy pathway in CS neurons may be associated with the pathophysiology exhibited in the neural network of CS patients.

Highlights

Cohen syndrome (CS) is a rare congenital, neurodevelopmental disorder that manifests clinical features such as obesity, hypotonia, intellectual disabilities, microcephaly, and distinctive facial features [1]
There were no gross defects regarding the morphology of the nuclei, ER, or mitochondria in CS fibroblasts, autophagic vacuoles (AVs), which are a hallmark of autophagy, accumulated tremendously in the cytosol of CS fibroblasts when compared to control fibroblasts (Fig. 1a)
To further examine autophagic activity in control and CS fibroblasts, autophagic flux assays were performed in the presence or absence of lysosomal inhibitors

Summary

Introduction

Cohen syndrome (CS) is a rare congenital, neurodevelopmental disorder that manifests clinical features such as obesity, hypotonia, intellectual disabilities, microcephaly, and distinctive facial features [1]. * Correspondence: cslimwk1@wku.ac.kr; leeja@hnu.kr 8Department of Pharmacology, Wonkwang University School of Medicine, 460 Iksan-daero, Iksan 54538, Korea 1Department of Biological Sciences and Biotechnology, Hannam University, 1646 Yuseongdaero, Yuseong-gu, Daejeon 34054, Korea Full list of author information is available at the end of the article gene ( known as COH1), which harbors up to 62 exons, and an open reading frame encoding 4022 amino acids and is generally involved in vesicle-mediated trafficking and intracellular protein transport [2].

Results

Conclusion