Dimethyl sulfoxide reduces hepatocellular lipid accumulation through autophagy induction.
Induction of autophagy is known not only to regulate cellular homeostasis but also to decrease triglyceride accumulation in hepatocytes. The aim of this study is to investigate whether DMSO (dimethyl sulfoxide) has a beneficial role in free fatty acid-induced hepatic fat accumulation.   In HepG2 cells, treatment with 0.5 mM palmitate for six hours significantly increased lipid and triglyceride (TG) accumulation, assessed by Oil-red O staining and TG quantification assay. Treatment with 0.01% DMSO for 16 h statistically reduced palmitate-induced TG contents. Pretreatment of 10 mM 3-methyladenine (3MA) for 2 h restored hepatocellular lipid contents, which were attenuated by treatment with DMSO. DMSO increased LC3-II conversion and decreased SQSTM1/p62 expression in a time and dose-dependent manner. In addition, the number of autophagosomes and autolysosomes, as seen under an electron microscopy, as well as the percentage of RFP-LAMP1 colocalized with GFP-LC3 dots in cells transfected with both GFP-LC3 and RFP-LAMP1, as seen under a fluorescent microscopy, also increased in DMSO-treated HepG2 cells. DMSO also suppressed p-eIF2α/p-EIF2S1, ATF4, p-AKT1, p-MTOR and p-p70s6k/p-RPS6KB2 expression as assessed by western blotting. Knockdown of ATF4 expression using siRNA suppressed ATF4 expression and phosphorylation of AKT1, MTOR and RPS6KB2, but increased LC3-II conversion. DMSO reduced not only soluble but also insoluble mtHTT (mutant huntingtin aggregates) expressions, which were masked in the presence of autophagy inhibitor. DMSO, a kind of chemical chaperone, activated autophagy by suppressing ATF4 expression and might play a protective role in the development of fatty acid-induced hepatosteatosis.
Brain Korea 21 Project for Medical Science; Yonsei University College of Medicine; Seoul, Korea.
Young Mi
YM
Song
Sun-Ok
SO
Song
Yong-Keun
YK
Jung
Eun-Seok
ES
Kang
Bong Soo
BS
Cha
Hyun Chul
HC
Lee
Byung-Wan
BW
Lee
D051701:Activating Transcription Factor 4 / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D050356:Lipid Metabolism / Q000187:drug effects*; D019308:Palmitic Acid / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D020836:Protein Structure, Quaternary; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism
C497109:ATF4 protein, human; D015415:Biomarkers; D010455:Peptides; D051701:Activating Transcription Factor 4; C097188:polyglutamine; D019308:Palmitic Acid; D051057:Proto-Oncogene Proteins c-akt; D004121:Dimethyl Sulfoxide