Regional difference in insulin inhibition of non-esterified fatty acid release from human adipocytes: relation to insulin receptor phosphorylation and intracellular signalling through the insulin receptor substrate-1 pathway (original) (raw)

Summary

Increased mobilization of non-esterified fatty acids (NEFA) from visceral as opposed to peripheral fat depots can lead to metabolic disturbances because of the direct portal link between visceral fat and the liver. Compared with peripheral fat, visceral fat shows a decreased response to insulin. The mechanisms behind these site variations were investigated by comparing insulin action on NEFA metabolism with insulin receptor signal transduction through the insulin receptor substrate-1 (IRS-1) pathway in omental (visceral) and subcutaneous human fat obtained during elective surgery. Insulin inhibited lipolysis and stimulated NEFA re-esterification. This was counteracted by wortmannin, an inhibitor of phosphaditylinositol (PI) 3-kinase. The effects of insulin on antilipolysis and NEFA re-esterification were greatly reduced in omental fat cells. Insulin receptor binding capacity, mRNA and protein expression did not differ between the cell types. Insulin was four times more effective in stimulating tyrosine phosporylation of the insulin receptor in subcutaneous fat cells (p < 0.001). Similarly, insulin was two to three times more effective in stimulating tyrosine phosphorylation of IRS-1 in subcutaneous fat cells (p < 0.01). This finding could be explained by finding that IRS-1 protein expression was reduced by 50 ± 8 % in omental fat cells (p < 0.01). In omental fat cells, maximum insulin-stimulated association of the p85 kDa subunit of PI 3-kinase to phosphotyrosine proteins and phosphotyrosine associated PI 3-kinase activity were both reduced by 50 % (p < 0.05 or better). Thus, the ability of insulin to induce antilipolysis and stimulate NEFA re-esterification is reduced in visceral adipocytes. This reduction can be explained by reduced insulin receptor autophosphorylation and signal transduction through an IRS-1 associated PI 3-kinase pathway in visceral adipocytes. [Diabetologia (1998) 41: 1343–1354]

Article PDF

Similar content being viewed by others

Author information

Authors and Affiliations

1. Department of Clinical Physiology, Karolinska Institute at Karolinska Hospital, Sweden, , , , , , SE
   J. R. Zierath
2. Bayer, West Haven, Connecticut, USA, , , , , , US
   J. N. Livingston
3. Department of Surgery, Karolinska Institute at Huddinge Hospital, Sweden, , , , , , SE
   Anders Thörne
4. Department of Medicine and Research Center, Karolinska Institute at Karolinska Hospital, Sweden, , , , , , SE
   Jan Bolinder, Signy Reynisdottir, Fredrik Lönnqvist & Peter Arner

Authors

1. J. R. Zierath
2. J. N. Livingston
3. Anders Thörne
4. Jan Bolinder
5. Signy Reynisdottir
6. Fredrik Lönnqvist
7. Peter Arner

Additional information

Received: 27 February 1998 and in revised form: 12 May 1998

Rights and permissions

About this article

Cite this article

Zierath, J., Livingston, J., Thörne, A. et al. Regional difference in insulin inhibition of non-esterified fatty acid release from human adipocytes: relation to insulin receptor phosphorylation and intracellular signalling through the insulin receptor substrate-1 pathway.Diabetologia 41, 1343–1354 (1998). https://doi.org/10.1007/s001250051075

Download citation

• Issue date: October 1998
• DOI: https://doi.org/10.1007/s001250051075