Static mechanical stretching accelerates lipid production in 3T3-L1 adipocytes by activating the MEK signaling pathway.
Understanding mechanotransduction in adipocytes is important for research of obesity and related diseases. We cultured 3T3-L1 preadipocytes on elastic substrata and applied static tensile strains of 12% to the substrata while inducing differentiation. Using an image processing method, we monitored lipid production for a period of 3-4 wk. The ratio of %-lipid area per field of view (FOV) in the stretched over nonstretched cultures was significantly greater than unity (P < 0.05), reaching ∼1.8 on average starting from experimental day ∼10. The superior coverage of the FOV by lipids in the stretched cultures was due to significantly greater sizes of lipid droplets (LDs) with respect to nonstretched cultures, starting from experimental day ∼10 (P < 0.05), and due to significantly more LDs per cell between days ∼10 and ∼17 (P < 0.05). The statically stretched cells also differentiated significantly faster than the nonstretched cells within the first ∼10 days (P < 0.05). Adding peroxisome proliferator-activated receptor-γ (PPARγ) antagonist did not change these trends, as the %-lipid area per FOV in the stretched cultures that received this treatment was still significantly greater than in the nonstretched cultures without the PPARγ antagonist (14.44 ± 1.96% vs. 10.21 ± 3%; P < 0.05). Hence, the accelerated adipogenesis in the stretched cultures was not mediated through PPARγ. Nonetheless, inhibiting the MEK/MAPK signaling pathway reduced the extent of adipogenesis in the stretched cultures (13.53 ± 5.63%), bringing it to the baseline level of the nonstretched cultures without the MEK inhibitor (10.21 ± 3.07%). Our results hence demonstrate that differentiation of adipocytes can be enhanced by sustained stretching, which activates the MEK signaling pathway.
Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Israel.
Naama
N
Shoham
Ruth
R
Gottlieb
Orna
O
Sharabani-Yosef
Uri
U
Zaretsky
Dafna
D
Benayahu
Amit
A
Gefen
D041721:3T3-L1 Cells / Q000166:cytology / Q000378:metabolism; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D050156:Adipogenesis / Q000502:physiology; D000328:Adult; D000818:Animals; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D002478:Cells, Cultured; D002648:Child; D006801:Humans; D020738:Leptin / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009765:Obesity / Q000503:physiopathology; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000378:metabolism; D013314:Stress, Mechanical; D014280:Triglycerides / Q000378:metabolism
D020738:Leptin; D008055:Lipids; D047495:PPAR gamma; D014280:Triglycerides; D020929:Mitogen-Activated Protein Kinase Kinases