Accessible Requires Authentication Published by De Gruyter September 18, 2018

Adipocyte aquaporin 7 (AQP7) expression in lean children and children with obesity. Possible involvement in molecular mechanisms of childhood obesity

Eleni Oikonomou, Eirini Kostopoulou, Andrea Paola Rojas-Gil, George Georgiou and Bessie E. Spiliotis

Abstract

Background

Aquaporin 7 (AQP7), a water/glycerol transporting protein, regulates adipocyte glycerol efflux and influences lipid and glucose homeostasis. Altered AQP7 expression in adults leads to impaired glycerol dynamics, adipocyte hypertrophy and it predisposes them to obesity and diabetes. To assess its possible involvement in childhood obesity, this study investigated the expression of adipocyte AQP7 in cultured adipocytes of children.

Methods

Primary in vitro differentiated adipocyte cultures were developed from surgical biopsies of subcutaneous abdominal adipose tissue from 61 (46 prepubertal, 15 pubertal) lean children (body mass index [BMI] <85%) and 41 (22 prepubertal, 19 pubertal) children with obesity (BMI >95%). AQP7 expression was studied by reverse transcription polymerase chain reaction and Western immunoblotting and insulin by enzyme-linked immunosorbent assay.

Results

AQP7 messenger RNA (mRNA) was increased in the younger obese prepubertal (YOP) children but decreased in the obese adolescents (OA) (p=0.014) who also had increased insulin and homeostatic model assessment – insulin resistance (HOMA-IR). Lean pubertal (LP) children and YOP had increased 41 kDa AQP7 protein expression (p=0.001 and p=0.005, respectively). The OA who expressed 34 kDa AQP7 had lower triglyceride (TG) levels than those who did not express it (p=0.013). In the lean children, TG were negatively correlated with 34 kDa AQP7 (p=0.033).

Conclusions

The lower AQP7 mRNA expression in the OA may reflect a predisposition to adipocyte hypertrophy and metabolic dysfunction, as in the adults, whereas the YOP may be protected from this. The increased 41 kDa AQP7 protein expression in the LP may reflect the increased energy requirements of puberty for glycerol while in the YOP it may also be protective against the development of adipocyte hypertrophy.


Corresponding author: Bessie E. Spiliotis, MD, Research Laboratory of the Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, University of Patras School of Medicine, 26504 Rio, Patras, Greece

  1. Disclosure statement: None declared.

  2. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  3. Research funding: IKY fellowships of excellence for postgraduate studies in Greece – Siemens program. State Scholarships Foundation, Funder Id: 10.13039/ 501100003447, Grant Number: SPhD/11230/13ß.

  4. Employment or leadership: None declared.

  5. Honorarium: None declared.

  6. Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

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Received: 2018-06-27
Accepted: 2018-08-13
Published Online: 2018-09-18
Published in Print: 2018-10-25

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