It has long been recognized that central (visceral) obesity is associated with adverse metabolic health including insulin resistance, yet peripheral (subcutaneous) body fat is healthful or benign, a distinction believed to underlie the sexually dimorphic risk of cardiometabolic disease with obesity. However, the molecular determinants that control the origins and physiology of these functionally distinct depots are poorly defined. Using conditional genetic engineering, we have identified a surprising role for the B cell lymphoma 6 (BCL6) transcriptional repressor in depot-specific adipose tissue programming. We find that BCL6 co-localizes with key adipocytic transcriptional regulators PPAR?, C/EBP, and EBF1 to control a metabolic gene regulatory network through cis-regulatory sites in differentiated adipocytes. Consequently, adipocyte-specific loss of BCL6 in utero results in spontaneous and selective expansion of subcutaneous, but not visceral, adipose tissue, identifying BCL6 as a new key regulator of sexually dimorphic obesity and distribution. Herein, we propose to dissect the genomic integration of BCL6 with nuclear receptor and hormonal signaling pathways to determine its role as a key regulator of adipose tissue distribution and function, using comprehensive cell and molecular, genomic, and physiologic approaches with endpoints of insulin sensitivity by euglycemic-hyperinsulinemic clamp, adipokine production, and lipid metabolism. Given that distinct adipose tissue depots exert differential risk of insulin resistance and cardiometabolic disease, our studies of BCL6 will reveal new therapeutic pathways to reduce the morbidity of obesity including type 2 diabetes mellitus (DM2).

Public Health Relevance

Abdominal obesity is highly associated with cardiac and metabolic disease, yet fat distributed just underneath the skin is healthful or benign. In this project, we elucidate a gene switch controlling body fat distribution. Insights from these studies may identify a therapeutic pathway to render obesity more healthful and treat type 2 diabetes mellitus.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK108987-04
Application #
9664609
Study Section
Molecular and Cellular Endocrinology Study Section (MCE)
Program Officer
Haft, Carol R
Project Start
2016-05-10
Project End
2021-03-31
Budget Start
2019-04-01
Budget End
2020-03-31
Support Year
4
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Northwestern University at Chicago
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
005436803
City
Chicago
State
IL
Country
United States
Zip Code
60611
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Hong, Hee-Kyung; Maury, Eleonore; Ramsey, Kathryn Moynihan et al. (2018) Requirement for NF-?B in maintenance of molecular and behavioral circadian rhythms in mice. Genes Dev 32:1367-1379