The effect of adipocyte differentiation on the capacity of 3T3-L1 cells to undergo apoptosis in response to growth factor deprivation.
OBJECTIVE
Little is known about the regulation of apoptosis in the adipocyte. Using the 3T3-L1 cell model of adipogenesis, we investigated whether induction of apoptosis by serum-starvation is differentiation-specific.


METHODS
Apoptosis was assessed by phase-contrast microscopy, Hoechst staining and DNA fragmentation. Protein expression levels were evaluated by immunoblot analysis.


RESULTS
Following serum deprivation, Hoechst staining revealed chromatin condensation and formation of apoptotic bodies in 3T3-L1 preadipocytes, but not in differentiated adipocytes. Similarly, although cell cultures of serum-starved 3T3-L1 preadipocytes displayed extensive apoptotic DNA fragmentation, this was barely detectable for cell cultures subjected to differentiation medium, in which 70-90% of the cells had assumed the mature phenotype. Consistent with the ability of the adipocytes to resist apoptosis, immunoblot analysis revealed that differentiated cell cultures expressed Bcl-2 and the endonuclease DNase I at higher and lower levels, respectively.


CONCLUSIONS
Expression of cell survival genes is modulated during 3T3-L1 adipocyte differentiation, potentially contributing to the state of resistance to apoptosis observed for mature 3T3-L1 adipocytes upon growth factor deprivation.
Department of Medicine and Biochemistry, Ottawa Civic Hospital Loeb Research Institute, University of Ottawa, Canada.
R
R
Magun
D L
DL
Boone
B K
BK
Tsang
A
A
Sorisky
D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology*; D000818:Animals; D017209:Apoptosis; D001562:Benzimidazoles; D002454:Cell Differentiation; D004396:Coloring Agents; D016895:Culture Media, Serum-Free; D053938:DNA Fragmentation; D006133:Growth Substances / Q000008:administration & dosage*; D051379:Mice
D001562:Benzimidazoles; D004396:Coloring Agents; D016895:Culture Media, Serum-Free; D006133:Growth Substances