Oxysterol-binding protein ORP3 rescues the Amyotrophic Lateral Sclerosis-linked mutant VAPB phenotype

Journal Article · Mon Feb 01 04:00:00 EST 2016 · Experimental Cell Research

DOI:https://doi.org/10.1016/J.YEXCR.2016.01.013· OSTI ID:22746407

Darbyson, Angie

A mutation in VAPB causes a familial form of Amyotrophic Lateral Sclerosis. The mutant protein (VAPB-P56S) is aggregate prone and blocks retrograde traffic from the endoplasmic reticulum (ER) Golgi intermediate compartment (ERGIC) including trafficking to the nuclear envelope (NE). Here we report a morphological screen where overexpression of oxysterol binding protein-related protein-3 (ORP3) rescued the mutant VAPB phenotype. It resolved the mutant VAPB-induced membrane expansions, restored solubility of the mutant protein in non-ionic detergent, and restored trafficking of Emerin to the NE. Knockdown of ORP3 or VAPB increased the intracellular level of phosphatidylinositol 4-phosphate (PtdIns4P). Decreasing PtdIns4P levels by inhibiting its synthesis reduced the severity of the mutant VAPB-induced membrane expansions and restored Emerin trafficking to the NE. Thus, VAPB and its interacting partners cooperatively regulate protein trafficking through the ERGIC by modulating PtdIns4P levels. - Graphical abstract: Overexpression of ORP3 rescues the mutant VAPB phenotype. It collectively regulates trafficking from the endoplasmic reticulum Golgi intermediate compartment (ERGIC) with VAPB and SAC1 by modulating intracellular levels of phosphatidylinositol 4-phosphate (PtdIns4P). - Highlights: • Co-overexpression of ORP3 rescues the mutant VAPB aggregation phenotype. • It restores mutant VAPB-induced protein trafficking defect. • VAPB and ORP3 collectively regulate intracellular PtdIns4P levels. • PtdIns4P plays a pivotal role in this VAPB-mediated protein trafficking step.

• OSTI ID: 22746407
• Journal Information: Experimental Cell Research, Journal Name: Experimental Cell Research Journal Issue: 1 Vol. 341; ISSN 0014-4827; ISSN ECREAL
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
DEFECTS
DETERGENTS
ENDOPLASMIC RETICULUM
EXPANSION
MEMBRANE PROTEINS
MEMBRANES
MUTANTS
MUTATIONS
PHENOTYPE
PHENYLALANINE
PHOSPHATES
PHOSPHOTRANSFERASES
SOLUBILITY
SYNTHESIS