Intrinsic depot-specific differences in the secretome of adipose tissue, preadipocytes, and adipose tissue-derived microvascular endothelial cells.
OBJECTIVE
Visceral adipose tissue (VAT) is more closely linked to insulin resistance than subcutaneous adipose tissue (SAT). We conducted a quantitative analysis of the secretomes of VAT and SAT to identify differences in adipokine secretion that account for the adverse metabolic consequences of VAT.


METHODS
We used lectin affinity chromatography followed by comparison of isotope-labeled amino acid incorporation rates to quantitate relative differences in the secretomes of VAT and SAT explants. Because adipose tissue is composed of multiple cell types, which may contribute to depot-specific differences in secretion, we isolated preadipocytes and microvascular endothelial cells (MVECs) and compared their secretomes to those from whole adipose tissue.


RESULTS
Although there were no discrete depot-specific differences in the secretomes from whole adipose tissue, preadipocytes, or MVECS, VAT exhibited an overall higher level of protein secretion than SAT. More proteins were secreted in twofold greater abundance from VAT explants compared with SAT explants (59% versus 21%), preadipocytes (68% versus 0%), and MVECs (62% versus 15%). The number of proteins in the whole adipose tissue secretome was greater than the sum of its cellular constituents. Finally, almost 50% of the adipose tissue secretome was composed of factors with a role in angiogenesis.


CONCLUSIONS
VAT has a higher secretory capacity than SAT, and this difference is an intrinsic feature of its cellular components. In view of the number of angiogenic factors in the adipose tissue secretome, we propose that VAT represents a more readily expandable tissue depot.
Hocking
Samantha L
SL
Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.
Wu
Lindsay E
LE
Guilhaus
Michael
M
Chisholm
Donald J
DJ
James
David E
DE
D017667:Adipocytes / Q000166:cytology / Q000502:physiology; D000273:Adipose Tissue / Q000502:physiology*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D003470:Culture Media; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D007333:Insulin Resistance / Q000502:physiology*; D050152:Intra-Abdominal Fat / Q000502:physiology*; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000502:physiology; D010446:Peptide Fragments / Q000302:isolation & purification; D010455:Peptides / Q000302:isolation & purification; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000276:immunology; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D050151:Subcutaneous Fat / Q000502:physiology*
D000596:Amino Acids; D003470:Culture Media; D010446:Peptide Fragments; D010455:Peptides; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011506:Proteins