title: The role of alkaline phosphatase in intracellular lipid accumulation in the human hepatocarcinoma cell line, HepG2.
abstract: Inhibition of tissue non-specific alkaline phosphatase (TNALP) decreases intracellular lipid accumulation in human preadipocytes and the murine preadipocyte cell line, 3T3-L1. Therefore, the current study was performed to determine if TNALP is required for intracellular lipid deposition in the human hepatocyte cell line, HepG2. Intracellular lipid accumulation, TNALP activity and peroxisome proliferator activated receptor (PPAR) γ gene expression were measured in HepG2 and 3T3-L1 cells in the presence and absence of the TNALP inhibitors levamisole and histidine. Sub-cellular TNALP activity was localized using cytochemical analysis. Both PPARγ gene expression and TNALP activity increased during intracellular lipid accumulation in HepG2 and 3T3-L1 cells. Inhibition of TNALP blocked intracellular lipid accumulation but did not alter expression of the PPARγ gene. In HepG2 cells, TNALP co-localized with adipophilin on the lipid droplet membrane. These data suggest a role for TNALP in lipid droplet formation, possibly downstream from PPARγ, within HepG2 and 3T3-L1 cells.
authors.affiliation: Department of Chemical Pathology, National Health Laboratory Service, University of Witwatersrand Medical School, Johannesburg, South Africa; Department of Biochemistry, College Of Medicine, University of Malawi, Blantyre, Malawi. Electronic address: chirambog1@gmail.com.
authors.forename: George M
authors.initials: GM
authors.lastname: Chirambo
authors.affiliation: Department of Chemical Pathology, National Health Laboratory Service, University of Witwatersrand Medical School, Johannesburg, South Africa. Electronic address: chantal.vanniekerk@up.ac.za.
authors.forename: Chantal
authors.initials: C
authors.lastname: van Niekerk
authors.affiliation: Department of Chemical Pathology, National Health Laboratory Service, University of Witwatersrand Medical School, Johannesburg, South Africa. Electronic address: nigel.crowther@nhls.ac.za.
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Crowther
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism; D050156:Adipogenesis; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D003593:Cytoplasm / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D050356:Lipid Metabolism; D051379:Mice; D047495:PPAR gamma / Q000378:metabolism*
chemical_list: D047495:PPAR gamma; C548267:ALPL protein, human; D000469:Alkaline Phosphatase
keywords: Adipogenesis; Alkaline phosphatase; HepG2; Lipid droplet; PPARgamma