TY - JOUR
T1 - Single-cell analysis of insulin-regulated fatty acid uptake in adipocytes
AU - Varlamov, Oleg
AU - Somwar, Romel
AU - Cornea, Anda
AU - Kievit, Paul
AU - Grove, Kevin L.
AU - Roberts, Charles T.
PY - 2010/9
Y1 - 2010/9
N2 - Increased body fat correlates with the enlargement of average fat cell size and reduced adipose tissue insulin sensitivity. It is currently unclear whether adipocytes, as they accumulate more triglycerides and grow in size, gradually become less insulin sensitive or whether obesity-related factors independently cause both the enlargement of adipocyte size and reduced adipose tissue insulin sensitivity. In the first instance, large and small adipocytes in the same tissue would exhibit differences in insulin sensitivity, whereas, in the second instance, adipocyte size per se would not necessarily correlate with insulin response. To analyze the effect of adipocyte size on insulin sensitivity, we employed a new single-cell imaging assay that resolves fatty acid uptake and insulin response in single adipocytes in subcutaneous adipose tissue explants. Here, we report that subcutaneous adipocytes are heterogeneous in size and intrinsic insulin sensitivity. Whereas smaller adipocytes respond to insulin by increasing lipid uptake, adipocytes with cell diameters larger than 80-100 μm are insulin resistant. We propose that, when cell size approaches a critical boundary, adipocytes lose insulin-dependent fatty acid transport. This negative feedback mechanism may protect adipocytes from lipid overload and restrict further expansion of adipose tissue, which leads to obesity and metabolic complications.
AB - Increased body fat correlates with the enlargement of average fat cell size and reduced adipose tissue insulin sensitivity. It is currently unclear whether adipocytes, as they accumulate more triglycerides and grow in size, gradually become less insulin sensitive or whether obesity-related factors independently cause both the enlargement of adipocyte size and reduced adipose tissue insulin sensitivity. In the first instance, large and small adipocytes in the same tissue would exhibit differences in insulin sensitivity, whereas, in the second instance, adipocyte size per se would not necessarily correlate with insulin response. To analyze the effect of adipocyte size on insulin sensitivity, we employed a new single-cell imaging assay that resolves fatty acid uptake and insulin response in single adipocytes in subcutaneous adipose tissue explants. Here, we report that subcutaneous adipocytes are heterogeneous in size and intrinsic insulin sensitivity. Whereas smaller adipocytes respond to insulin by increasing lipid uptake, adipocytes with cell diameters larger than 80-100 μm are insulin resistant. We propose that, when cell size approaches a critical boundary, adipocytes lose insulin-dependent fatty acid transport. This negative feedback mechanism may protect adipocytes from lipid overload and restrict further expansion of adipose tissue, which leads to obesity and metabolic complications.
KW - Cell size
KW - Insulin resistance
KW - Obesity
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U2 - 10.1152/ajpendo.00330.2010
DO - 10.1152/ajpendo.00330.2010
M3 - Article
C2 - 20570821
AN - SCOPUS:77956850352
SN - 0193-1849
VL - 299
SP - E486-E496
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 3
ER -