Maung et al. report that mutations in the laminin A (LMNA) gene in patients with familial partial lipodystrophy 2 associate with suppressed lipid metabolism and mitochondrial pathways, as well as increased inflammation. The cover art is a pseudocolored transmission electron micrograph of swollen and disorganized adipocyte mitochondria in Lmna-knockout adipocytes. Image credit: Jessica N. Maung.
MRE11, a breast tumor suppressor and component of the MRE11-RAD50-NBS1 (MRN) complex, plays a critical role in DNA end resection and initiation of ATM-dependent DNA damage signaling. However, the precise mechanisms governing MRE11 function in the DNA damage response (DDR) remain incompletely understood. Here, we found that MRE11 is deacetylated by the SIRT2 sirtuin deacetylase and breast tumor suppressor, which promotes DNA binding to facilitate DNA end resection and ATM-dependent signaling. SIRT2 deacetylase activity promoted DNA end resection. SIRT2 further complexed with and deacetylated MRE11 at conserved lysine (K) 393 in response to DNA double-strand breaks (DSBs), which promoted MRE11 localization and DNA binding at DSBs but not interaction with RAD50, NBS1, or CtIP. Moreover, MRE11 K393 deacetylation by SIRT2 promoted ATM-dependent signaling. Our findings define a mechanism regulating MRE11 binding to DNA through SIRT2 deacetylation, elucidating a critical upstream signaling event directing MRE11 function in the DDR and providing insight into how SIRT2 dysregulation leads to genomic instability and tumorigenesis.
Fatmata Sesay, Hui Zhang, Priya Kapoor-Vazirani, Andrew T. Jung, Mark E. Essien, Amanda J. Bastien, Nho C. Luong, Xu Liu, PamelaSara E. Head, Duc M. Duong, Xiaofeng Yang, Zachary S. Buchwald, Xingming Deng, Nicholas T. Seyfried, David S. Yu
Large-cohort genome-wide association studies (GWAS) for alcohol use disorder (AUD) drug treatment outcomes and AUD risk have repeatedly identified genetic loci which are splicing quantitative trait loci for the fibronectin III domain containing 4 (FNDC4) gene in the brain. However, FNDC4 function in the brain and how it might contribute to AUD pathophysiology remain unclear. In the present study, we characterized GWAS loci-associated FNDC4 splice isoforms and demonstrated that FNDC4 alternative splicing results in loss-of-function for FNDC4. We also investigated FNDC4 function using CRISPR/cas9 editing, and the creation of human induced pluripotent stem cell (iPSC)-derived neural organoids joined with single-nucleus RNA sequencing, a series of studies which showed that FNDC4 knock-out (KO) resulted in a striking shift in the relative proportions of glutamatergic and GABAergic neurons in iPSC-derived forebrain organoids as well as changes in their electrical activity. We further explored potential mechanism(s) of FNDC4-dependent neurogenesis with results that suggested a role for FNDC4 in mediating neural cell surface interactions. In summary, this series of experiments indicates that FNDC4 plays a role in regulating cerebral cortical neurogenesis in the brain. This regulation may contribute to the response to AUD pharmacotherapy as well as the effects of alcohol on the brain.
Xiujuan Zhu, August J. John, Sooan Kim, Li Wang, Enci Ding, Jing Zheng, Ateka Saleh, Irene Marín-Goñi, Abedalrahman Jomaa, Huanyao Gao, Meijie Wang, Ching Man Wai, Irene Moon, Cindy Chen, Alireza Agahi, Brandon J. Coombes, Tony M. Kerr, Nobuyoshi Suto, Liewei Wang, Mark A. Frye, Joanna M. Biernacka, Victor M. Karpyak, Hu Li, Richard M. Weinshilboum, Duan Liu
WHIM syndrome is an immunodeficiency caused by autosomal dominant hyperfunctional mutations in chemokine receptor CXCR4 that promote panleukopenia due to BM retention. We previously reported a preclinical gene therapy protocol involving allele-nonspecific Cxcr4 CRISPR/Cas9 inactivation, leveraging the known in vivo dominance of Cxcr4+/o (+, WT; o, inactivated) hematopoietic stem cells (HSCs) for autologous BM engraftment and leukocyte reconstitution over HSCs with other Cxcr4 genotypes. Here, we show that without BM conditioning, this approach is not able to correct leukopenia in WHIM mice. We therefore modified the protocol by adding conditioning with a non-genotoxic CD117-targeted immunotoxin, CD117-antibody-saporin-conjugate (CD117-ASC). With this change, donor-derived blood cells rapidly reached ~95% chimerism after transplantation, which was stable without adverse events for more than 400 days. Mice receiving edited HSCs showed rapid normalization of absolute myeloid cell counts, the key blood subset responsible for WHIM syndrome. In competitive transplants using equal numbers of edited and unedited donor HSCs, over 80% of blood cells originated from the edited population, predominantly with the Cxcr4+/o genotype. These results provide proof of principle that CRISPR/Cas9-mediated inactivation of the Cxcr4 disease allele, combined with non-genotoxic HSC-targeted conditioning, may offer a safe and effective gene therapy strategy generalizable to all WHIM mutations.
Ji-Liang Gao, Zhanzhuo Li, Rafael Calderon-Perez, Antonia Pavek, Lina Kim, David H. McDermott, Philip M. Murphy
Vessels encapsulating tumor clusters (VETC), a distinct vascular pattern in hepatocellular carcinoma (HCC), facilitates non-invasive metastasis in whole cluster. The interaction between VETC and tumor microenvironment requires exploration. Here, we found that compared to human Non-VETC-HCCs, VETC-tumors exhibited more PD1+CD8+ T cells and Tregs, especially TNFRSF4+Tregs and Ki67+Tregs which showed increased immunosuppressive and proliferative activity. Such immunosuppressive status was also detected in tumor emboli of VETC-HCCs, and Treg density in emboli was positively associated with metastatic cell proliferation. VETC-HCCs revealed abundance correlation, closer spatial proximity, and stronger immunosuppressive ligand-receptor interactions between TNFRSF4+Tregs/Ki67+Tregs and PD1+CD8+ T cells. Depleting Tregs in mice reduced PD1+CD8+ T cells in primary lesions, tumor emboli and metastatic foci of VETC-allografts, and attenuated allograft metastasis. TGF-β1 levels were upregulated in endothelial cells of VETC-HCCs and associated with TNFRSF4+Tregs/Ki67+Tregs enrichment. Disrupting VETC formation decreased endothelial TGF-β1 expression, and reduced TNFRSF4+Tregs/Ki67+Tregs, PD1+CD8+ T cells, Treg/CD8+ T cells ratio. Collectively, VETC may enhance Tregs’ activity via TGF-β1, while Tregs promote and sustain CD8+ T cell exhaustion through immune inhibitory ligand-receptor interaction, thereby shaping immunosuppressive microenvironment and enabling tumor cluster to carry such niche to disseminate. These findings disclose mechanisms of tumor immune microenvironment formation and provide rationales for precision medicine.
Bi-Yu Huang, Zheng-Qi Mi, Xiao-Yu Zhang, Yu-Chen Ji, Meng-Zhi Wu, Zi-Feng Cheng, Chen Xie, Shuai He, Jing Zhu, Jian-Hong Fang, Chong Wu, Bin-Kui Li, Yun-Fei YUAN, Limin Zheng, Shi-Mei Zhuang
Aged individuals with somatic TP53 mutations manifest clonal hematopoiesis (CH) and are at high risk of developing myeloid neoplasms. However, the underlying mechanisms are not fully understood. Here we show that inflammatory stress confers a competitive advantage to p53 mutant hematopoietic stem and progenitor cells (HSPCs) by activating the NLRP1 inflammasome and increasing the secretion of pro-inflammatory cytokines such as IL-1β, inhibiting wild type (WT) HSPC fitness in a paracrine fashion. During aging, mutant p53 dysregulates pre-mRNA splicing in HSPCs, leading to enhanced NF-κB activation and increased secretion of IL-1β and IL-6, thereby generating a chronic inflammatory bone marrow microenvironment. Furthermore, blocking IL-1β with IL-1β neutralizing antibody or inhibiting IL-1β secretion using gasdermin D (GSDMD) inhibitor decreases the fitness of p53 mutant HSPCs. Thus, our findings uncover an important role for mutant p53 in regulating inflammatory signaling in CH and suggest that curbing inflammation may prevent the progression of TP53-mutant clonal hematopoiesis to myeloid neoplasms.
Sisi Chen, Sergio Barajas, Sasidhar Vemula, Yuxia Yang, Ed Simpson, Hongyu Gao, Rudong Li, Farzaneh Behzadnia, Sarah C. Nabinger, David A. Schmitz, Hongxia Chen, Wenjie Cai, Shiyu Xiao, Ruyue Luo, Mohammed Abdullahel Amin, Maegan L. Capitano, James P. Ropa, Aidan Fahey, Shuyi Zhou, Tiffany M. Mays, Magdalena Sotelo, Hao Pan, Sophie K. Hu, Sophia Veranga, Moiez Ali, Maria Shumilina, Reuben Kapur, Kehan Ren, Yuzhi Jia, Huiping Liu, Irum Khan, Yasmin Abaza, Jessica K. Altman, Elizabeth A. Eklund, Lucy A. Godley, Christine R. Zhang, Peng Ji, Seth L. Masters, Ben A. Croker, H. Scott Boswell, George E. Sandusky, Zhonghua Gao, Lindsey D. Mayo, Sharon A. Savage, Stephanie Halene, Yali Dou, Leonidas C. Platanias, Madina Sukhanova, Yunlong Liu, Omar Abdel-Wahab, Yan Liu
Therapies targeting the glucagon-like peptide 1 (GLP-1) receptor have revolutionized the treatment of obesity and diabetes. This series of reviews, curated by Dr. Dan Drucker, describes the latest research in this fast-moving in field, from our evolving understanding of the mechanism of GLP-1 receptor signaling to the medicines’ impact on inflammation and the consequences for heart, kidney, and brain health. The reviews also explore the impact of these medicines on conditions beyond their initial indications, including cancer and neurodegenerative disease risk.
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In this episode, Dr. Seth J. Zost presents an antibody lineage from a single donor that binds the active site of influenza neuraminidase, cross-reacts with antigenically diverse viruses, and protects mice from infection...