ATP-binding cassette transporter A1 (ABCA1) expression in adipose tissue and its modulation with insulin resistance in obesity
Received 19 November 2018
Accepted for publication 8 January 2019
Published 25 February 2019 Volume 2019:12 Pages 275—284
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 2
Editor who approved publication: Dr Konstantinos Tziomalos
Vinnyfred Vincent,1 Himani Thakkar,1 Sandeep Aggarwal,2 Asit Ranjan Mridha,3 Lakshmy Ramakrishnan,4 Archna Singh1
1Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India; 2Department of Surgical Disciplines, All India Institute of Medical Sciences, New Delhi, India; 3Department of Pathology, All India Institute of Medical Sciences, New Delhi, India; 4Department of Cardiac Biochemistry, All India Institute of Medical Sciences, New Delhi, India
Purpose: Adipose tissue dysfunction is at the center of metabolic dysfunctions associated with obesity. Through studies in isolated adipocytes and mouse models, ATP-binding cassette transporter A1 (ABCA1) expression in the adipose tissue has been shown to regulate high-density lipoprotein (HDL) cholesterol levels in the circulation and insulin sensitivity at both adipose tissue and whole-body levels. We aimed to explore the possible link between ABCA1 expression in the adipose tissue and metabolic derangements associated with obesity in humans.
Patients and methods: This exploratory study among individuals who were lean (body mass index [BMI]: 22.3±0.34 kg/m2, n=28) and obese (BMI: 44.48±5.3 kg/m2, n=34) compared the expression of ABCA1, adiponectin and GLUT4 (SLC2A4) in visceral and subcutaneous adipose tissue using quantitative real-time PCR and immunohistochemistry. Homeostatic model assessment for insulin resistance (HOMA-IR) and adipose tissue insulin resistance (adipo-IR) were used as insulin resistance markers.
Results: Visceral adipose tissue from individuals who were obese had significantly lower ABCA1 (P=0.04 for mRNA and protein) and adiponectin (P=0.001 for mRNA) expression compared to that from lean individuals. Subcutaneous adipose tissue did not show any significant difference in the expression. When individuals were divided into insulin-sensitive (IS) and insulin-resistant (IR) groups based on HOMA-IR, IR individuals had lower ABCA1 (P=0.0001 for mRNA and P=0.009 for protein) expression compared to IS individuals in visceral adipose tissue, but not in subcutaneous adipose tissue. The difference was significant after adjusting for age, gender and BMI. ABCA1 mRNA expression in visceral adipose tissue correlated negatively with both HOMA-IR (r=–0.44, P=0.0003) and adipo-IR (r=–0.35, P=0.005) after adjusting for age, gender and BMI. ABCA1 expression in either visceral or subcutaneous adipose tissue did not have any significant correlation with HDL cholesterol levels or mean adipocyte area.
Conclusion: Obesity and insulin resistance are associated with lower expression of ABCA1 in visceral adipose tissue in humans.
Keywords: metabolic syndrome, cholesterol, diabetes, adiponectin
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