Browsing by Author "Xu, Jiazhi"

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    ATG14 plays a critical role in hepatic lipid droplet homeostasis
    (Elsevier, 2023) Huang, Menghao; Zhang, Yang; Park, Jimin; Chowdhury, Kushan; Xu, Jiazhi; Lu, Alex; Wang, Lu; Zhang, Wenjun; Ekser, Burcin; Yu, Liqing; Dong, X. Charlie; Biochemistry and Molecular Biology, School of Medicine
    Background & aims: Autophagy-related 14 (ATG14) is a key regulator of autophagy. ATG14 is also localized to lipid droplet; however, the function of ATG14 on lipid droplet remains unclear. In this study, we aimed to elucidate the role of ATG14 in lipid droplet homeostasis. Methods: ATG14 loss-of-function and gain-of-function in lipid droplet metabolism were analyzed by fluorescence imaging in ATG14 knockdown or overexpression hepatocytes. Specific domains involved in the ATG14 targeting to lipid droplets were analyzed by deletion or site-specific mutagenesis. ATG14-interacting proteins were analyzed by co-immunoprecipitation. The effect of ATG14 on lipolysis was analyzed in human hepatocytes and mouse livers that were deficient in ATG14, comparative gene identification-58 (CGI-58), or both. Results: Our data show that ATG14 is enriched on lipid droplets in hepatocytes. Mutagenesis analysis reveals that the Barkor/ATG14 autophagosome targeting sequence (BATS) domain of ATG14 is responsible for the ATG14 localization to lipid droplets. Co-immunoprecipitation analysis illustrates that ATG14 interacts with adipose triglyceride lipase (ATGL) and CGI-58. Moreover, ATG14 also enhances the interaction between ATGL and CGI-58. In vitro lipolysis analysis demonstrates that ATG14 deficiency remarkably decreases triglyceride hydrolysis. Conclusions: Our data suggest that ATG14 can directly enhance lipid droplet breakdown through interactions with ATGL and CGI-58.
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    Genetically programmed alternative splicing of NEMO mediates an autoinflammatory disease phenotype
    (The American Society for Clinical Investigation, 2022) Lee, Younglang; Wessel, Alex W.; Xu, Jiazhi; Reinke, Julia G.; Lee, Eries; Kim, Somin M.; Hsu, Amy P.; Zilberman-Rudenko, Jevgenia; Cao, Sha; Enos, Clinton; Brooks, Stephen R.; Deng, Zuoming; Lin, Bin; de Jesus, Adriana A.; Hupalo, Daniel N.; Piotto, Daniela G.P.; Terreri, Maria T.; Dimitriades, Victoria R.; Dalgard, Clifton L.; Holland, Steven M.; Goldbach-Mansky, Raphaela; Siegel, Richard M.; Hanson, Eric P.; Pediatrics, School of Medicine
    Host defense and inflammation are regulated by the NF-κB essential modulator (NEMO), a scaffolding protein with a broad immune cell and tissue expression profile. Hypomorphic mutations in inhibitor of NF-κB kinase regulatory subunit gamma (IKBKG) encoding NEMO typically present with immunodeficiency. Here, we characterized a pediatric autoinflammatory syndrome in 3 unrelated male patients with distinct X-linked IKBKG germline mutations that led to overexpression of a NEMO protein isoform lacking the domain encoded by exon 5 (NEMO-Δex5). This isoform failed to associate with TANK binding kinase 1 (TBK1), and dermal fibroblasts from affected patients activated NF-κB in response to TNF but not TLR3 or RIG-I-like receptor (RLR) stimulation when isoform levels were high. By contrast, T cells, monocytes, and macrophages that expressed NEMO-Δex5 exhibited increased NF-κB activation and IFN production, and blood cells from these patients expressed a strong IFN and NF-κB transcriptional signature. Immune cells and TNF-stimulated dermal fibroblasts upregulated the inducible IKK protein (IKKi) that was stabilized by NEMO-Δex5, promoting type I IFN induction and antiviral responses. These data revealed how IKBKG mutations that lead to alternative splicing of skipping exon 5 cause a clinical phenotype we have named NEMO deleted exon 5 autoinflammatory syndrome (NDAS), distinct from the immune deficiency syndrome resulting from loss-of-function IKBKG mutations.
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    Go to the scene: TH9 cells superior migration ability to the lungs explains their exceptional anticancer efficacy
    (BMJ, 2025-04-28) Xu, Jiazhi; Apetoh, Lionel; Microbiology and Immunology, School of Medicine
    Antibodies against immune checkpoints are now routinely administered as a first line of treatment against metastatic lung cancer. Resistance to immune checkpoint inhibitors is, however, frequent, underscoring the need to find alternative treatments. Adoptive T-cell therapy has recently proven effective in treating patient's refractory to immune checkpoint inhibitors. This provides impetus to characterize the T-cell subsets best able to tackle tumors. The anticancer activities of IL-9-producing CD4 T helper cells (TH9 cells) were identified in melanoma in 2012. TH9 cells feature strong antimelanoma effects thanks to their production of interleukin (IL)-9 and the activation of innate and adaptive immune effectors. The ability of TH9 cells to prevent the growth of triple-negative breast cancer (TNBC) and osteosarcoma (OS), which commonly metastasize to the lungs, is elusive. In this commentary, we discuss the findings of Chen et al reported in the JITC demonstrating that TH9 cells are lung-tropic and eliminate TNBC and OS cells developing in the lungs. We also highlight how these investigations are in line with recent studies indicating that the adoptive transfer of IL-9-producing T cells eliminate aggressive cancers, including hematological tumors like leukemia and solid tumors such as glioblastoma. Altogether, these findings over the past 13 years support the clinical evaluation of TH9 cells in the adoptive therapy of cancer.