Static Mechanical Stretching Accelerates Lipid Production in 3T3-L1 Adipocytes by Activating the MEK Signaling Pathway

Naama Shoham, Ruth Gottlieb, Orna Shaharabani-Yosef, Uri Zaretsky, Dafna Benayahu, Amit Gefen


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 weeks. The ratio of %-lipid area per field of view (FOV) in the stretched over non-stretched 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 non-stretched cultures, starting from experimental day ~10 (p<0.05), and due to significantly more LDs per cell in-between days ~10 and ~17 (p<0.05). The statically-stretched cells also differentiated significantly faster than the non-stretched cells within the first ~10 days (p<0.05). Adding PPARγ antagonist did not change these trends, as the %-lipid area per FOV in the stretched cultures which received this treatment was still significantly greater than in the non-stretched cultures without the PPARγ antagonist (14.44±1.96% versus 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 non-stretched 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.

  • Mechanotransduction
  • Obesity
  • Tensile strain
  • 3T3-L1 preadipocytes
  • Differentiation