Insulin resistance in African-American and Caucasian women: Differences in lipotoxicity, adipokines, and gene expression in adipose tissue and muscle

Latasha M. Smith, Aiwei Yao-Borengasser, Tasha Starks, Mark Tripputi, Philip A. Kern, Neda Rasouli

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Objectives: We tested whether African-American (AA) women are different from Caucasian women in regard to lipotoxicity, adipokines, and gene expression in adipose tissue and muscle. Design: Insulin sensitivity (SI), plasma adipocytokine levels, intramyocellular lipid (IMCL), and the expression of candidate genes in adipose tissue and muscle were measured in AA and Caucasian women. Setting: This study was performed in an ambulatory general clinical research center. Subjects: Subjects were healthy, nondiabetic AA and Caucasian women. Interventions: There were no interventions. Main Outcome Measures: Comparison of SI, IMCL, plasma adiponectin, and the expression of candidate genes regulating adipogenesis, lipogenesis, and inflammation in adipose tissue and muscle. Results: AA had lower plasma adiponectin and IMCL when compared with Caucasian women with similar SI. In sc adipose tissue (SAT), the expression of genes involved in adipogenesis including peroxisomal proliferator-activated receptor-γ(PPARγ) and lipin-1β were also reduced in SAT of AA subjects (19%, P = 0.06, and 25%, P = 0.05, respectively). Similarly, 1-acylglycerol-3-phosphate acyltransferase 2 (AGPAT 2), stearoyl-coenzyme A desaturase-1 (SCD1), and CD36 mRNA expression was significantly reduced in SAT by 19, 54, and 28% respectively (P < 0.01 for all) in AA compared with Caucasian women. Yet the expression of CD68 in SAT was similar in both ethnic groups. Gene expression studies in muscle revealed a 31% reduction in expression of AGPAT 2 and a 72% reduction in SCD1 genes in AA. Conclusion: AA women demonstrated lower expression of several PPARγ-responsive genes in adipose tissue, lower plasma adiponectin, and decreased IMCL levels as compared with Caucasians, which suggests that African-Americans may be protected from lipotoxicity. Together these data suggest significant ethnic differences in the pathophysiology of insulin resistance.

Original languageEnglish
Pages (from-to)4441-4448
Number of pages8
JournalJournal of Clinical Endocrinology and Metabolism
Volume95
Issue number9
DOIs
StatePublished - Sep 2010

Bibliographical note

Funding Information:
This work was supported by a Merit Review Grant from the Veterans Administration (to N.R.) , Grants DK080327 and DK071349 (to P.A.K.), and Grant UL1RR029884 from the National Center for Research Resources.

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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