Abstract
Aberrant mitochondrial fission plays a pivotal role in the pathogenesis of skeletal muscle insulin resistance. However, fusion-fission dynamics are physiologically regulated by inherent tissue-specific and nutrient-sensitive processes that may have distinct or even opposing effects with respect to insulin sensitivity. Based on a combination of mouse population genetics and functional in vitro assays, we describe here a regulatory circuit in which peroxisome proliferator-activated receptor γ (PPARγ), the adipocyte master regulator and receptor for the thiazolidinedione class of antidiabetic drugs, controls mitochondrial network fragmentation through transcriptional induction of Bnip3. Short hairpin RNA-mediated knockdown of Bnip3 in cultured adipocytes shifts the balance toward mitochondrial elongation, leading to compromised respiratory capacity, heightened fatty acid β-oxidation-associated mitochondrial reactive oxygen species generation, insulin resistance, and reduced triacylglycerol storage. Notably, the selective fission/Drp1 inhibitor Mdivi-1 mimics the effects of Bnip3 knockdown on adipose mitochondrial bioenergetics and glucose disposal. We further show that Bnip3 is reciprocally regulated in white and brown fat depots of diet-induced obesity and leptin-deficient ob/ob mouse models. Finally, Bnip3(-/-) mice trade reduced adiposity for increased liver steatosis and develop aggravated systemic insulin resistance in response to high-fat feeding. Together, our data outline Bnip3 as a key effector of PPARγ-mediated adipose mitochondrial network fragmentation, improving insulin sensitivity and limiting oxidative stress.
Original language | English |
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Pages (from-to) | 2591-605 |
Number of pages | 15 |
Journal | Diabetes |
Volume | 65 |
Issue number | 9 |
DOIs | |
Publication status | Published - Sept 2016 |
Keywords
- 3T3-L1 Cells
- Adipocytes/metabolism
- Animals
- Cell Differentiation/genetics
- Cell Line
- Female
- Glucose/metabolism
- Immunoblotting
- Immunohistochemistry
- Insulin Resistance/genetics
- Insulin/metabolism
- Male
- Membrane Proteins/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Fluorescence
- Mitochondria/metabolism
- Mitochondrial Dynamics/genetics
- Mitochondrial Proteins/genetics
- Obesity/genetics
- PPAR gamma/genetics
- Radioimmunoprecipitation Assay
- Reverse Transcriptase Polymerase Chain Reaction