• Journal of Life Science
• /
• v.30 no.8
• /
• pp.708-712
• /
• 2020

Vacuolar protein sorting (VPS) 26b is a newly discovered member of the retromer complex; it is encoded by a single-copy gene located on mouse chromosome 9, and the complex has been reported as being composed of proteins VPS26, VPS29, and VPS35. We have previously shown that mice lacking VPS26b exhibited no significant body size or health issues. Although retromer components are widely expressed in mouse tissue, their roles have not yet been completely elucidated. The current study investigates whether the VPS26b-associated retromer complex can be used as a neurodegeneration model. Previously, we observed a significant reduction in VPS35 and VPS29 in the brain cells of in VPS26b-deficient mice as well as an absence of the VPS26b-VPS29-VPS35 retromer complex despite the normal presence of VPS26a-VPS29-VPS35. Recent studies have suggested that low levels of VPS35 can lead to Alzheimer's disease-like phenotypes including cognitive memory deficits. In this study, we successfully demonstrate an association between the absence of the VPS26b-VPS29-VPS35 retromer complex, reduced cell density in the CA3 region of the hippocampus, and learning disability in VPS26b knock-out mice. The results also indicate that the VPS26b-associated retromer complex affects neurodegenerative disorders and learning processes.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.22 no.6
• /
• pp.581-587
• /
• 2019

Arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome is a rare autosomal recessive multisystemic disease that is associated with the liver, kidney, skin, and central nervous and musculoskeletal systems. ARC occurs as a result of mutations in the VPS33B (Vacuolar protein sorting 33 homolog B) or VIPAR (VPS33B interacting protein, apical-basolateral polarity regulator) genes. A female infant presented with neonatal cholestasis with a severe clinical outcome. She was diagnosed with ARC syndrome using targeted exome sequencing (TES). Exome sequencing revealed compound heterozygous mutations, c.707A>T and c.239+5G>A, in VPS33B, where c.707A>T was a novel variant; the resultant functional protein defects were predicted via in silico analysis. c.239+5G>A, a pathogenic mutation that affects splicing, is found in less than 0.1% of the general population. Invasive techniques, such as liver biopsies, did not contribute to a differential diagnosis of ARC syndrome; thus, early TES together with clinical presentations constituted an apparently accurate diagnostic procedure.