Commitment of 3T3-F442A cells to adipocyte differentiation takes place during the first 24-36 h after adipogenic stimulation: TNF-alpha inhibits commitment.
We studied the commitment of 3T3-F442A cells during stimulation with adipogenic serum or growth hormone. Confluent 3T3-F442A preadipocytes were incubated with adipogenic medium for increasing times; the number of adipose clusters, GPDH activity, and lipid accumulation were evaluated. Results show that cell commitment took place during the first 24-36 h after stimulation under adipogenic conditions. Then, cultures underwent a 2-fold increase in total cell number through selective multiplication of committed cells, followed by a dramatic decrease in colony-forming ability and 300- to 1000-fold raise in GPDH activity. Cell commitment was not modulated by insulin, but this hormone stimulated clonal expansion of committed cells and lipogenesis. Commitment was inhibited by TNF-alpha at concentrations as low as 5 ng/ml, and by retinoic acid. The results show that TNF-alpha inhibits adipose conversion at two different levels: at concentrations as low as 5 ng/ml, it blocks commitment, and at concentrations of 100 ng/ml or higher the cytokine seems to block mitotic expansion and other steps of differentiation after cell commitment. The identification of a specific time for cell commitment would allow the study of the early genes that might regulate cell reprogramming into adipocytes.
Castro-Muñozledo
Federico
F
Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del I.P.N. Apdo. Postal 14-740, Mexico City, 07000, Mexico.
Beltrán-Langarica
Alicia
A
Kuri-Harcuch
Walid
W
D016475:3T3 Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D019070:Cell Lineage / Q000187:drug effects / Q000502:physiology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D050536:Glycerol-3-Phosphate Dehydrogenase (NAD+); D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D008055:Lipids / Q000096:biosynthesis; D051379:Mice; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
D017077:Culture Media, Conditioned; D007328:Insulin; D008055:Lipids; D014409:Tumor Necrosis Factor-alpha; D014212:Tretinoin; D005993:Glycerolphosphate Dehydrogenase; D050536:Glycerol-3-Phosphate Dehydrogenase (NAD+)