Peroxisome proliferator-activated receptor gamma (PPARγ) is a critical regulator of carbohydrate and lipid metabolism, adipocyte differentiation and inflammatory response. Post-translational modification of PPARγ and its degradation involve several pathways, including the ubiquitin-proteasome system. Here, we identified F-box only protein 9 (FBXO9) as an E3 ubiquitin ligase of PPARγ. We screened interacting partners of PPARγ using immunoprecipitation and mass spectrometric analysis and identified FBXO9 as an E3 ubiquitin ligase of PPARγ. FBXO9 directly interacted with PPARγ through the activation function-1 domain and ligand-binding domain. FBXO9 decreased the protein stability of PPARγ through induction of ubiquitination. We found that the F-box motif of FBXO9 was required for its ubiquitination function. The activity of PPARγ was significantly decreased by FBXO9 overexpression. Furthermore, FBXO9 overexpression in 3T3-L1 adipocytes resulted in decreased levels of endogenous PPARγ and suppression of adipogenesis. These results suggest that FBXO9 is an important enzyme that regulates the stability and activity of PPARγ through ubiquitination.
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http://dx.doi.org/10.1038/emm.2016.31 | DOI Listing |
J Biol Chem
January 2025
The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada, M5G 1X8; Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, ON, Canada, M5G 2M9. Electronic address:
The NUMB gene encodes a conserved adaptor protein with roles in asymmetric cell division and cell fate determination. First described as an inhibitor of Notch signaling, multi-functional NUMB proteins regulate multiple cellular pathways through protein complexes with ubiquitin ligases, polarity proteins and the endocytic machinery. The vertebrate NUMB protein isoforms were identified over two decades ago, yet the majority of functional studies exploring NUMB function in endocytosis, cell migration and adhesion, development and disease have largely neglected the potential for distinct isoform activity in design and interpretation.
View Article and Find Full Text PDFJ Biol Chem
January 2025
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA. Electronic address:
Carboxyl-terminus of Hsp70-Interacting Protein (CHIP) is an E3 ubiquitin ligase that marks misfolded substrates for degradation. Hyper-activation of CHIP has been implicated in multiple diseases, including cystic fibrosis and cancer, suggesting that it may be a potential drug target. However, there are few tools available for exploring this possibility.
View Article and Find Full Text PDFPharm Biol
December 2025
The Affiliated Hospital, Changchun University of Chinese Medicine, Changchun, China.
Context: The decline in ovarian reserve is a major concern in female reproductive health, often associated with oxidative stress and mitochondrial dysfunction. Although ginsenoside Rg1 is known to modulate mitophagy, its effectiveness in mitigating ovarian reserve decline remains unclear.
Objective: To investigate the role of ginsenoside Rg1 in promoting mitophagy to preserve ovarian reserve.
Viruses
January 2025
Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
The tripartite-motif protein 56 (TRIM56) is a RING-type E3 ubiquitin ligase whose functions were recently beginning to be unveiled. While the physiological role(s) of TRIM56 remains unclear, emerging evidence suggests this protein participates in host innate defense mechanisms that guard against viral infections. Interestingly, TRIM56 has been shown to pose a barrier to viruses of distinct families by utilizing its different domains.
View Article and Find Full Text PDFPlants (Basel)
January 2025
Corteva Agriscience, 7000 NW 62nd Ave, Johnston, IA 50131, USA.
Maize lethal necrosis (MLN) is a significant threat to food security in Sub-Saharan Africa (SSA), with limited commercial inbred lines displaying tolerance. This study analyzed the transcriptomes of four commercially used maize inbred lines and a non-adapted inbred line, all with varying response levels to MLN. RNA-Seq revealed differentially expressed genes in response to infection by maize chlorotic mottle virus (MCMV) and sugarcane mosaic virus (SCMV), the causative agents of MLN.
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