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Intrinsic depot-specific differences in the secretome of adipose tissue, preadipocytes, and adipose tissue-derived microvascular endothelial cells.

Hocking SL, Wu LE, Guilhaus M, Chisholm DJ, James DE - Diabetes (2010)

Bottom Line: 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.In view of the number of angiogenic factors in the adipose tissue secretome, we propose that VAT represents a more readily expandable tissue depot.

View Article: PubMed Central - PubMed

Affiliation: Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.

ABSTRACT

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.

Research design and 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.

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Related in: MedlinePlus

A: White adipose tissue (WAT) explants secretory proteins are secreted in greater amounts from VAT. B: Preadipocyte secreted proteins are secreted at greater amounts from visceral-derived preadipocytes. C: Endothelial cell secretory proteins are secreted at greater amounts from visceral-derived endothelial cells. WAT explants, preadipocytes, and microvascular endothelial cells from visceral and subcutaneous WAT depots were cultured in media containing two different isotopes of arginine and lysine. LAC–CILAIR mass spectrometry was performed, and isotopic ratios were calculated. The histogram shows distribution of visceral-to-subcutaneous ratios for proteins detected. Note the use of the natural log scale.
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Figure 2: A: White adipose tissue (WAT) explants secretory proteins are secreted in greater amounts from VAT. B: Preadipocyte secreted proteins are secreted at greater amounts from visceral-derived preadipocytes. C: Endothelial cell secretory proteins are secreted at greater amounts from visceral-derived endothelial cells. WAT explants, preadipocytes, and microvascular endothelial cells from visceral and subcutaneous WAT depots were cultured in media containing two different isotopes of arginine and lysine. LAC–CILAIR mass spectrometry was performed, and isotopic ratios were calculated. The histogram shows distribution of visceral-to-subcutaneous ratios for proteins detected. Note the use of the natural log scale.

Mentions: We hypothesized there would be differences in protein secretion from VAT and SAT. Adipose tissue explants from epididymal (VAT) and inguinal (SAT) depots were incubated for 48 h in the presence of “heavy” and “medium” isotopes of arginine and lysine, respectively. Medium was collected, mixed in equal ratio, and subjected to LAC. Proteins were precipitated, resolved by SDS-PAGE, trypsin-digested, and subjected to quantitative mass spectrometry (Table 1 and supplementary data available in an online appendix at http://diabetes.diabetesjournals.org/cgi/content/full/db10-0483/DC1). A total of 145 proteins were identified, of which 86 (60%) were predicted to contain an NH2-terminal signal peptide using SignalP. Of these, 51 proteins (59%) were present at >2-fold higher abundance in conditioned medium from VAT than SAT, whereas only 18 proteins (21%) were at >2-fold higher abundance in conditioned medium from SAT than VAT. The frequency distribution of the visceral-to-subcutaneous ratio for detected proteins is shown in Fig. 2A. Proteins without a signal peptide are nonspecifically released, newly synthesized cytosolic proteins. The distribution for these background proteins with no signal peptide resembles a normal distribution, whereas the distribution for proteins with a signal peptide is skewed to the right. This indicates that release of true secretory proteins into conditioned medium is increased from VAT relative to SAT. The normal distribution of nonsecretory background proteins indicates a similar amount of tissue was present in VAT and SAT samples.


Intrinsic depot-specific differences in the secretome of adipose tissue, preadipocytes, and adipose tissue-derived microvascular endothelial cells.

Hocking SL, Wu LE, Guilhaus M, Chisholm DJ, James DE - Diabetes (2010)

A: White adipose tissue (WAT) explants secretory proteins are secreted in greater amounts from VAT. B: Preadipocyte secreted proteins are secreted at greater amounts from visceral-derived preadipocytes. C: Endothelial cell secretory proteins are secreted at greater amounts from visceral-derived endothelial cells. WAT explants, preadipocytes, and microvascular endothelial cells from visceral and subcutaneous WAT depots were cultured in media containing two different isotopes of arginine and lysine. LAC–CILAIR mass spectrometry was performed, and isotopic ratios were calculated. The histogram shows distribution of visceral-to-subcutaneous ratios for proteins detected. Note the use of the natural log scale.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 2: A: White adipose tissue (WAT) explants secretory proteins are secreted in greater amounts from VAT. B: Preadipocyte secreted proteins are secreted at greater amounts from visceral-derived preadipocytes. C: Endothelial cell secretory proteins are secreted at greater amounts from visceral-derived endothelial cells. WAT explants, preadipocytes, and microvascular endothelial cells from visceral and subcutaneous WAT depots were cultured in media containing two different isotopes of arginine and lysine. LAC–CILAIR mass spectrometry was performed, and isotopic ratios were calculated. The histogram shows distribution of visceral-to-subcutaneous ratios for proteins detected. Note the use of the natural log scale.
Mentions: We hypothesized there would be differences in protein secretion from VAT and SAT. Adipose tissue explants from epididymal (VAT) and inguinal (SAT) depots were incubated for 48 h in the presence of “heavy” and “medium” isotopes of arginine and lysine, respectively. Medium was collected, mixed in equal ratio, and subjected to LAC. Proteins were precipitated, resolved by SDS-PAGE, trypsin-digested, and subjected to quantitative mass spectrometry (Table 1 and supplementary data available in an online appendix at http://diabetes.diabetesjournals.org/cgi/content/full/db10-0483/DC1). A total of 145 proteins were identified, of which 86 (60%) were predicted to contain an NH2-terminal signal peptide using SignalP. Of these, 51 proteins (59%) were present at >2-fold higher abundance in conditioned medium from VAT than SAT, whereas only 18 proteins (21%) were at >2-fold higher abundance in conditioned medium from SAT than VAT. The frequency distribution of the visceral-to-subcutaneous ratio for detected proteins is shown in Fig. 2A. Proteins without a signal peptide are nonspecifically released, newly synthesized cytosolic proteins. The distribution for these background proteins with no signal peptide resembles a normal distribution, whereas the distribution for proteins with a signal peptide is skewed to the right. This indicates that release of true secretory proteins into conditioned medium is increased from VAT relative to SAT. The normal distribution of nonsecretory background proteins indicates a similar amount of tissue was present in VAT and SAT samples.

Bottom Line: 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.In view of the number of angiogenic factors in the adipose tissue secretome, we propose that VAT represents a more readily expandable tissue depot.

View Article: PubMed Central - PubMed

Affiliation: Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.

ABSTRACT

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.

Research design and 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.

Show MeSH
Related in: MedlinePlus