Effects of accumulation of lipid droplets on load transfer between and within adipocytes.
Adipogenesis, a process of cell proliferation followed by the accumulation of lipid droplets (LDs), is accompanied by morphological changes in adipocytes, leading to a gradual rise in the structural stiffness of these cells. The increase in cellular structural stiffness can potentially influence the localized deformations of adjacent adipocytes in weight-bearing fat tissues, which, based on previous work, may accelerate intracytoplasmatic lipid production to form even larger and more tightly packed intracellular LDs. This process is based on mechanotransduction phenomena which are hypothesized (again, following empirical studies), to play a critical role in "en mass" adipocyte hypertrophy, and hence are important to characterize through computational modeling. Accordingly, we examined here how maturing adipocytes may affect localized loads acting on adjacent immature cells, using a set of finite element models of adipocytes embedded in an extracellular matrix. The peak strain energy density at the plasma membrane (PM) of the adipocytes, when constructs were externally loaded, was found to depend on the levels of lipid accumulation in the neighboring cells if the external compressive and shear deformations were large enough ([Formula: see text] and [Formula: see text], respectively). The mechanosignaling transduces through the PM and could therefore affect intracellular pathways to produce more lipid contents. Our results support the theory of deformation-induced differentiation in adipocytes. The findings are thus relevant in the context of a sedentary lifestyle, in which sustained deformations of weight-bearing adipose tissues may activate a positive feedback loop that promotes the "en mass" differentiation of cells, which subsequently increases the total mass of living fat tissues.
Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel.
Mor
M
Ben-Or Frank
Naama
N
Shoham
Dafna
D
Benayahu
Amit
A
Gefen
D017667:Adipocytes / Q000166:cytology* / Q000502:physiology*; D050156:Adipogenesis / Q000502:physiology; D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D019245:Compressive Strength / Q000502:physiology; D003198:Computer Simulation; D055119:Elastic Modulus; D005109:Extracellular Matrix / Q000502:physiology*; D006801:Humans; D066292:Lipid Droplets / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008954:Models, Biological; D033081:Shear Strength / Q000502:physiology; D013314:Stress, Mechanical