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Factors that influence retinol-binding protein 4-transthyretin interaction are not altered in overweight subjects and overweight subjects with type 2 diabetes mellitus

  • Retinol-binding protein 4 (RBP4) is an adipokine bound in plasma to transthyretin (TTR), which prevents its glomerular filtration and subsequent catabolism in the kidney. Alterations of this interaction have been Suggested to be implicated in the elevation of RBP4 that are thought to contribute to the development Of insulin resistance associated with obesity and type 2 diabetes mellitus (T2DM). However, the factors linking RBP4 to TTR in humans are not clear. Therefore, this Study evaluated parameters influencing the RBP4-TTR interaction and their relation to obesity and T2DM. The RBP4 and TTR levels were quantified in plasma of 16 lean controls, 28 overweight controls, and 14 overweight T2DM patients by enzyme-linked immunosorbent assay. Transthyretin isoforms involved in RBP4 binding were determined by linear matrix-assisted laser desorption/ionization-time of flight-mass spectrometry after RBP4 coimmunoprecipitation. Holo-RBP4 (retinol-bound) and apo-RBP4 (retinol-free) were assessed by immunoblotting using nondenaturatingRetinol-binding protein 4 (RBP4) is an adipokine bound in plasma to transthyretin (TTR), which prevents its glomerular filtration and subsequent catabolism in the kidney. Alterations of this interaction have been Suggested to be implicated in the elevation of RBP4 that are thought to contribute to the development Of insulin resistance associated with obesity and type 2 diabetes mellitus (T2DM). However, the factors linking RBP4 to TTR in humans are not clear. Therefore, this Study evaluated parameters influencing the RBP4-TTR interaction and their relation to obesity and T2DM. The RBP4 and TTR levels were quantified in plasma of 16 lean controls, 28 overweight controls, and 14 overweight T2DM patients by enzyme-linked immunosorbent assay. Transthyretin isoforms involved in RBP4 binding were determined by linear matrix-assisted laser desorption/ionization-time of flight-mass spectrometry after RBP4 coimmunoprecipitation. Holo-RBP4 (retinol-bound) and apo-RBP4 (retinol-free) were assessed by immunoblotting using nondenaturating polyacrylamide gel electrophoresis. Plasma levels of both RBP4 and TTR did not differ among the groups of lean controls, overweight controls, and overweight T2DM subjects. Using RBP4 immunoprecipitation, 4 mass signals were observed for TTR representing native, S-cysteinylated, S-cysteinglycinylated, and S-glutathionylated TTR. No differences in peak intensity of TTR isoforms were observed among the groups. Moreover, no differences in the ratio of holo- and apo-RBP4 were evident. The results suggest that circulating RBP4 and TTR were not affected by human obesity or T2DM, which might be attributed to the absence of alterations of TTR isoforms and the ratio of holo- and apo-RBP4 that might modify the TTR-RBP4 interaction.show moreshow less

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Author:Simone K. Frey, Joachim Spranger, Andrea HenzeORCiDGND, Andreas F. H. Pfeiffer, Florian J. SchweigertORCiDGND, Jens RailaORCiDGND
URL:http://www.sciencedirect.com/science/journal/00260495
DOI:https://doi.org/10.1016/j.metabol.2009.05.003
ISSN:0026-0495
Document Type:Article
Language:English
Year of first Publication:2009
Year of Completion:2009
Release Date:2017/03/25
Source:Metabolism. - ISSN 0026-0495. - 58 (2009), 10, S. 1386 - 1392
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Ernährungswissenschaft
Peer Review:Referiert