Alkaline phosphatase is involved in the control of adipogenesis in the murine preadipocyte cell line, 3T3-L1.
OBJECTIVE
As alkaline phosphatase may play a role in cell differentiation, our aim was to study the possible role of this enzyme in the differentiation of preadipocytes (3T3-L1 cells) into adipocytes.


METHODS
3T3-L1 cells were grown in medium containing insulin, dexamethasone and IBMX to induce adipogenesis. Adipogenesis was measured using the triglyceride-specific dye, oil red O at 0, 3, 7 and 11 days after initiation of adipogenesis in the presence or absence of the alkaline phosphatase inhibitors, levamisole, histidine and Phe-Gly-Gly. Intracellular localisation of the enzyme was detected using ELF-phosphatase, a fluorescent substrate and alkaline phosphatase gene expression was assessed using RT-PCR.


RESULTS
Alkaline phosphatase activity was detected in untransformed cells (1.91+/-0.62 mU/mg protein) and activity increased 11.5+/-1.4-fold after 11 days treatment with transformation medium and 5.3+/-0.3-fold in transformation medium containing levamisole (p<0.05). Triglyceride content of cells increased 3.1+/-0.2-fold after 11 days treatment with transformation medium and 2.1+/-0.3-fold in the presence of levamisole (p<0.005). Histidine inhibited adipogenesis and alkaline phosphatase to a greater extent than did levamisole, but Phe-Gly-Gly had no effect on these variables. Alkaline phosphatase was localised around the lipid droplets of the cells. Gene expression of alkaline phosphatase increased during adipogenesis.


CONCLUSIONS
This study demonstrates that tissue-nonspecific alkaline phosphatase is present in 3T3-L1 cells and that it may play a role in the control of adipogenesis.
Ali
Aus Tariq
AT
Department of Chemical Pathology, National Health Laboratory Service, School of Anatomical Sciences, University of the Witwatersrand Medical School, Johannesburg, South Africa.
Penny
Clem B
CB
Paiker
Janice E
JE
van Niekerk
Chantal
C
Smit
Aletta
A
Ferris
William F
WF
Crowther
Nigel J
NJ
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006639:Histidine / Q000494:pharmacology; D007978:Levamisole / Q000494:pharmacology; D050356:Lipid Metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013997:Time Factors
D003470:Culture Media; D007978:Levamisole; D006639:Histidine; D000469:Alkaline Phosphatase