PexRAP Inhibits PRDM16-Mediated Thermogenic Gene Expression

Abstract

Summary How the nuclear receptor PPARγ regulates the development of two functionally distinct types of adipose tissue, brown and white fat, as well as the browning of white fat, remains unclear. Our previous studies suggest that PexRAP, a peroxisomal lipid synthetic enzyme, regulates PPARγ signaling and white adipogenesis. Here we show that PexRAP is an inhibitor of brown adipocyte gene expression. PexRAP inactivation promoted adipocyte browning, increased energy expenditure and decreased adiposity. Identification of PexRAP-interacting proteins suggests that PexRAP function extends beyond its role as a lipid synthetic enzyme. Notably, PexRAP interacts with importin-β1, a nuclear import factor, and knockdown of PexRAP in adipocytes reduced the levels of nuclear phospholipids. PexRAP also interacts with PPARγ, as well as PRDM16, a critical transcriptional regulator of thermogenesis, and disrupts the PRDM16-PPARγ complex, providing a potential mechanism for PexRAP-mediated inhibition of adipocyte browning. These results identify PexRAP as an important regulator of adipose tissue remodeling.

Fetal alcohol spectrum disorder predisposes to metabolic abnormalities in adulthood

“…Genes directly associated with adipogenesis and obesity, including growth hormone 1 (gh1) and dehydrogenase/reductase 7 (dhrs7b), were also uniquely dysregulated in EAE larvae in response to HFHC diet ( Figure 6, I and J, and refs. [51][52][53]. Although no gene appears to singlehandedly explain the propensity for diet-induced VAT gain in EAE individuals, shifts in the expression of genes relevant to metabolism and lipid handling suggest that a suite of transcriptional changes likely contributes to this phenotype.…”

Peroxisome-derived lipids regulate adipose thermogenesis by mediating cold-induced mitochondrial fission

“…OCR in control and Pex16-knockdown BAT SVF cells was measured using an XF24 Extracellular Flux Analyzer with a FluxPak (Seahorse Bioscience). The cells were seeded and grown to confluence on XF24 cell culture microplates before treatment with differentiation media, as previously described (46). On day 2, the cells were treated with scrambled or Pex16 shRNA lentivirus in the maintenance media.…”

“…Human embryonic kidney 293T (HEK293T) cells and COS-7 cells were maintained in DMEM supplemented with 10% FBS. Stromal vascular fractions from mouse iWAT and BAT were isolated, immortalized, and differentiated into adipocytes as previously reported (46). Briefly, confluent BAT SVF cells were treated with DMEM/F12 supplemented with 0.5 μM isobutylmethylxanthine, 5 μM dexamethasone, 125 μM indomethacin, 1 μM rosiglitazone, 1 nM T3, and 0.02 μM insulin.…”

“…Mitochondrial morphology assay. BAT SVF cells stably expressing Mito-roGFP were seeded in 24-well plates with high performance #1.5 cover glass bottoms (Cellvis P24-1.5H-N), grown to confluence and then treated with brown adipocyte differentiation cocktail as previously described (46). Four days after the initiation of differentiation, the cells were infected with scrambled, Pex16, or GNPAT shRNA lentivirus in the differentiation medium.…”

Deciphering the Roles of PPARγ in Adipocytes via Dynamic Change of Transcription Complex

“…For example, TLE3 is a white-selective cofactor that competes with PRDM16 for PPARγ interaction to specify lipid storage or thermogenic gene programs ( 66 ). In addition to transcriptional factors and cofactors, PexRAP, a peroxisomal lipid synthetic enzyme interacts with PPARγ and PRDM16 and disrupts PRDM16-mediated gene expression ( 67 ). Last but not least, it has to be noted that nuclear factor I-A (NFIA) is recently reported to co-localize with PPARγ at the brown fat specific enhancers and facilitate PPARγ chromatin accessibility for induction of brown fat gene programs through mechanisms independent of the PPARγ/PRDM16 complex ( 68 ).…”