Differentiation-dependent regulation of the cyclooxygenase cascade during adipogenesis suggests a complex role for prostaglandins.
OBJECTIVE
A thorough understanding of the mechanisms of adipocyte differentiation and metabolism is important for the prevention and/or treatment of obesity and its complications, including type 2 diabetes mellitus. A complex role for prostaglandins (PGs) in adipogenesis is suggested. We examined the expression and cellular localization of enzymes in the cyclooxygenase (COX) cascade that synthesize PGs as well as the PG profile as a function of differentiation status in 3T3-L1 cells.


METHODS
Murine 3T3-L1 preadipocytes were used as a model for studies of adipocyte differentiation induced by a hormone cocktail and compared with the parental fibroblastic line NIH 3T3. Both cell lines were incubated in maintenance medium or differentiation medium. Nine days after differentiation, the expression of enzymes in the COX cascade was evaluated by immunoblot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry, and PG formation was examined using enzyme immunoassay.


RESULTS
A differentiation-dependent diminution of COX-1 and COX-2 mRNA and cognate proteins in 3T3-L1 cells was observed. PG release, including PGE(2), 6-keto PGF(1alpha), PGD(2) and 15d-PGJ(2), significantly decreased following differentiation in 3T3-L1 cells (anova/Tukey, p < 0.05). However, microsomal PGE synthase (mPGES) and lipocalin-type PGD synthase (L-PGDS) were selectively upregulated. Immunocytochemistry revealed that COX-1 and COX-2 became intracellularly more diffuse upon differentiation, whereas mPGES was redistributed to the nuclear compartment.


CONCLUSIONS
Regulation of PG formation and COX-2 expression in 3T3-L1 cells is differentiation-dependent and involves changes in the levels of gene expression of the individual isoforms as well as redistribution of the enzymes within cellular compartments.
Xie
Y
Y
Department of Obstetrics and Gynecology, Laboratory of Perinatal Research, The Ohio State University, College of Medicine and Public Health, Columbus, OH 43210, USA.
Kang
X
X
Ackerman
W E
WE
Belury
M A
MA
Koster
C
C
Rovin
B H
BH
Landon
M B
MB
Kniss
D A
DA
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000201:enzymology; D050156:Adipogenesis / Q000502:physiology*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D051545:Cyclooxygenase 1 / Q000032:analysis; D051546:Cyclooxygenase 2 / Q000032:analysis; D005786:Gene Expression Regulation / Q000502:physiology; D007150:Immunohistochemistry / Q000379:methods; D007155:Immunologic Factors / Q000096:biosynthesis; D051379:Mice; D041681:NIH 3T3 Cells; D047495:PPAR gamma / Q000032:analysis; D015230:Prostaglandin D2 / Q000031:analogs & derivatives / Q000096:biosynthesis; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*; D011453:Prostaglandins / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis
C097240:15-deoxy-delta(12,14)-prostaglandin J2; D007155:Immunologic Factors; D047495:PPAR gamma; D011453:Prostaglandins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015230:Prostaglandin D2