title: ALS-associated P56S-VAPB mutation restrains 3T3-L1 preadipocyte differentiation.
abstract: Amyotrophic lateral sclerosis (ALS), which is the most common motor neuron disease in adults, is a neurodegenerative disease that involves the selective and systematic death of upper and lower motor neurons. In addition to the motor neuron death, altered metabolic functions, such as dyslipidemia, have also been reported for ALS patients; however, the underlying mechanism remains unknown. In the present study, we investigated the effects of ALS-associated P56S-vesicle-associated membrane proteinassociated protein B (VAPB), P56S-VAPB on 3T3-L1 preadipocyte differentiation and on the expression of differentiation-associated genes and unfolded protein response (UPR)-related genes. Experiments with 3T3-L1 cells transfected with wild-type (Wt)-VAPB and P56S-VAPB expression vectors showed that the size of lipid droplets was markedly smaller in P56S-VAPB-expressing cells, although fat accumulated intracellularly. In P56S-VAPB-expressing cells, increased the expression of PPARγ2, aP2, and C/EBPα, the genes deeply involved in adipocyte differentiation, was not observed. Furthermore, the expression levels of the UPR-related ATF4 and CHOP genes were found to be enhanced in the P56S-VAPB-expressing cells. From these results, P56S-VAPB was found to suppress adipocyte differentiation by promoting the activation of the ATF4-CHOP pathway. Given previous reports showing increased ATF4 and CHOP expression levels in neurons of ALS patients, results from the present study suggest that dyslipidemia is caused by enhanced ATF4-CHOP pathway in the adipose tissue of ALS patients.
authors.affiliation: Interdisciplinary Graduate School of Science and Technology, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Tokutake
authors.affiliation: Graduate School of Agriculture, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Gushima
authors.affiliation: Graduate School of Agriculture, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan.
authors.forename: Honami
authors.initials: H
authors.lastname: Miyazaki
authors.affiliation: Department of Interdisciplinary Genome Sciences and Cell Metabolism, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shimosato
authors.affiliation: Interdisciplinary Graduate School of Science and Technology, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan; Graduate School of Agriculture, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan; Department of Interdisciplinary Genome Sciences and Cell Metabolism, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 8304 Minamiminowa, Kamiina, Nagano 399-4598, Japan. Electronic address: yonekura@shinshu-u.ac.jp.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yonekura
mesh_terms: D041721:3T3-L1 Cells; D051701:Activating Transcription Factor 4 / Q000378:metabolism; D017667:Adipocytes / Q000166:cytology*; D000690:Amyotrophic Lateral Sclerosis; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D017931:DNA Primers; D051379:Mice; D009154:Mutation; D016133:Polymerase Chain Reaction; D051742:Transcription Factor CHOP / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics*
chemical_list: C081452:Atf4 protein, mouse; D017931:DNA Primers; C497250:Ddit3 protein, mouse; C496748:VAPB protein, human; D033921:Vesicular Transport Proteins; D051701:Activating Transcription Factor 4; D051742:Transcription Factor CHOP
keywords: ALS; Adipocyte; Differentiation; UPR; VAPB