Research Article
Abstract
Orphan GPCRs of the GPRC5 family regulate macrophage activity and vascular contractility by dimerizing with other GPCRs, but pharmacological modulation of this process has not been explored. We previously identified the dimerization interface of receptor GPRC5B and show here that both its mutation and inhibition by a decoy peptide disturbed the interaction with the prostaglandin E2 receptor EP2 in macrophages, resulting in reduced EP2 signaling, enhanced migration and phagocytosis, and protection from bacterial peritonitis in mice. Furthermore, we show that a similar interface exists in related receptor GPRC5C, and, the same as in GPRC5B, mutation or inhibition by decoy peptide improved host defense. Through a virtual docking screen, we identified a small molecule inhibitor of both GPRC5B and GPRC5C dimerization, K303MP20, and showed that it reduced EP2 signaling, enhanced macrophage activity, and improved host defense in bacterial peritonitis and influenza A infection. Interestingly, K303MP20 not only blocked dimerization between GPRC5B/C and EP2, but also with prostacyclin receptor IP and angiotensin II receptor AT1, resulting in reduced AT1-dependent contraction and enhanced IP-dependent relaxation in human and murine smooth muscle cells. In vivo, K303MP20 did not affect basal blood pressure, but protected mice from angiotensin II–induced hypertension. Taken together, inhibition of orphan GPCR dimerization by small molecules is feasible and improves infection control and arterial hypertension.
Authors
Jeonghyeon Kwon, Margherita Persechino, Jingchen Shao, Jamal Shamsara, Birgit Spitznagel, Isabelle Salwig, Miloslav Sanda, Stefan Offermanns, Peter Kolb, Nina Wettschureck
Abstract
Glioblastoma (GBM), isocitrate dehydrogenase-WT (IDH-WT) (WHO grade 4) is the most common malignant glioma in adults and is characterized by a hypoxic and immunosuppressive tumor microenvironment (TME). Bone marrow–derived tumor-associated macrophages (TAMs) dominate the immune landscape in GBM and are recruited to the perinecrotic niche following the onset of necrosis. C-type lectin domain–containing 5A (CLEC5A) has the strongest association with poor clinical outcomes among immune-related genes in GBM and is preferentially expressed in hypoxic, perinecrotic TAMs. CLEC5A overexpression promotes TAM polarization toward an immunosuppressive phenotype and secretion of immunoregulatory cytokines. Using the replication-competent avian sarcoma-leukosis virus long terminal repeat with a splice acceptor (RCAS)/tumor virus A (tv-a) system GBM model with bone marrow transplantation from Clec5a–/– donor mice, we demonstrated that CLEC5A loss prolonged survival, delayed tumor progression, and attenuated TME immunosuppression. Mechanistically, podoplanin (PDPN) expressed on glioma cells directly engaged CLEC5A and triggered downstream Syk/JAK/STAT3 signaling in TAMs. Pharmacologic Syk inhibition suppressed glioma growth, diminished TAM infiltration and polarization, reversed the immunosuppressive TME, and prolonged survival in vivo. Collectively, our findings indicate that the PDPN/CLEC5A/Syk/STAT3 axis orchestrates TAM polarization and TME immunosuppression in the perinecrotic niche of GBM, highlighting CLEC5A/Syk as a promising therapeutic target for reversing the immunosuppressive TME and improving outcomes.
Authors
Jiabo Li, Xuya Wang, Luqing Tong, Bo Feng, Ling-kai Shih, Steven M. Markwell, Hannah Nuszen, Tomasz Gruchala, Nicholas G. Lam, Petros Basakis, Erika Ruiz-Yamamoto, Deyu Fang, Roger Stupp, Xuejun Yang, Daniel J. Brat
Abstract
The liver plays a critical role in lipid homeostasis, where lipids are either secreted as VLDLs or stored in lipid droplets (LDs). However, the regulatory mechanisms governing these 2 interconnected processes remain poorly understood. Here, we demonstrate that SEC16B functions as a lipid-responsive regulator in the liver, promoting VLDL secretion and LD expansion to handle lipid flux and maintain lipid homeostasis. Genome-wide association studies have identified SNPs in SEC16B to be highly associated with serum lipid levels in humans. Hepatic Sec16b deficiency decreases serum lipid levels by impairing VLDL secretion via disruption of COPII-mediated intracellular trafficking and through mechanisms partially independent of microsomal triglyceride transfer protein–mediated ApoB lipidation. SEC16B partially localizes at ER-LD contact sites and promotes LD expansion by facilitating the targeting of ER proteins to LDs. More importantly, suppression of Sec16b dramatically lowers serum lipid levels and reduces atherosclerotic lesion size in Ldlr null mice. These data reveal a mechanism that coordinates VLDL and LD metabolism and suggest SEC16B as a potential therapeutic target for atherosclerosis treatment.
Authors
Wei Lu, Zhiming Zhao, Donald Molina, Huaxun Fan, Ruicheng Shi, Ye Tian, Raja Gopoju, Tiantian Yang, Xinyuan Zhang, Yanqiao Zhang, Kai Zhang, Jaume Amengual, Bo Wang
Abstract
The inflammatory response resulting from the abnormal accumulation of metabolites has been implicated in the pathogenesis of organ fibrosis; however, its role and underlying mechanisms in renal fibrosis remain unclear. In this study, we observed a negative correlation between fumarate hydratase (FH) expression and the degree of renal fibrosis. Loss of FH function was associated with heightened inflammation and exacerbated tubulointerstitial damage in the kidney. Moreover, FH deficiency aggravated fibrosis in both the liver and lungs. Mechanistically, the depletion of FH in renal tubular cells led to fumarate accumulation. Fumarate directly succinated A-kinase anchoring protein 12 at cysteine 670, thereby diminishing its capacity to inhibit the activity of protein kinase Cζ (PKCζ). This process exacerbated renal inflammation and fibrosis by activating the downstream PKCζ/NF-κB and PKCζ/β-catenin pathways. Additionally, the upregulation of FH through adeno-associated virus 2/9–mediated FH overexpression markedly mitigated renal inflammation and fibrosis. These findings highlighted the important role of fumarate accumulation in the advancement of renal fibrosis, supporting FH as a potential therapeutic target in renal fibrosis.
Authors
Shuai Sun, Xu-yang Yan, Yu-hang Dong, Jian-min You, Zhen-yu Guo, Dong-xue Lv, Shuai-shuai Xie, Rui Hou, Xiang-yu Li, Ju-tao Yu, Xiao-yu Shen, Jie Wei, Zhen-yu Song, Zi-qi Chen, Yun-long Zhu, Xing-xin Xu, Juan Jin, Jia-gen Wen, Hao Wang, Xiao-ming Meng, Wei Wang
Abstract
Dominant mutations in progranulin (GRN) gene cause frontotemporal lobar degeneration (FTLD-GRN), whereas homozygous GRN mutations lead to neuronal ceroid lipofuscinosis, a childhood neurodegenerative disorder. While recent transcriptomic studies reveal profound glial and neuronal pathology in FTLD-GRN at the disease end stage, the mechanism that disrupts glia-neuron homeostasis remains unclear. Using induced pluripotent stem cell–derived cortical organoids, we showed that GRN–/– and GRNR493X mutations led to precocious astrogliosis that promoted neuronal stress and synaptic loss. Single-cell transcriptomics and histopathology analyses revealed a robust activation in the TGF-β signaling pathway in GRN–/– and GRNR493X/R493X astrocytes, which was accompanied by features of immune activation, loss of synaptic support, and abundant pTDP-43+ fibrils in astroglial cytoplasm, a feature characteristic of FTLD-GRN. Intriguingly, blocking TGF-β signaling mitigated astroglial activation and pTDP-43 proteinopathy in GRN–/– organoids. Together, these results provide insights into the cell-autonomous role of astroglial activation in neurodegeneration caused by progranulin deficiency.
Authors
Arren C. Ramsey, Xiao-Yan Tang, Magdalena J. Macias, Patricia R. Nano, Rufei Lu, Brian Benito, Cameron M. Lau, Jisu Park, Jiasheng Zhang, Wandy Beatty, Tanzila Mukhtar, Arnold R. Kriegstein, Aparna Bhaduri, Elise Marsan, Eric J. Huang
Abstract
De novo heterozygous variants in CUGBP Elav-like family member 2 (CELF2) have recently been associated with a rare neurodevelopmental disorder, yet the mechanisms linking specific variants to distinct clinical phenotypes remain poorly understood. Here, we reported a cohort of 18 individuals and provided evidence that variants causing CELF2 mislocalization, but not protein-null variants, were associated with seizures. Using proband-derived human cortical neurons and transgenic mouse models, we demonstrated that CELF2 underwent activity-dependent nucleocytoplasmic shuttling in excitatory neurons and that its cytoplasmic retention caused neuronal hyperactivity, elevated seizure susceptibility, and learning and memory deficits. We further found that cytoplasmic CELF2 regulated mRNAs critical for synaptic function and neuronal excitability and implicated in epileptic seizures and intellectual disability. Drug screening further identified AKT signaling as a key regulator of CELF2 nucleocytoplasmic shuttling and a candidate target for reversing neuronal hyperactivity. Together, our findings expand the clinical and genetic spectrum of CELF2-related neurodevelopmental disorders and establish a variant-specific mechanism that links CELF2 mislocalization to neuronal hyperactivity, seizures, and cognitive impairment.
Authors
Michelle Hua, Mohamad-Reza Aghanoori, Melissa J. MacPherson, Yi Ren, Shehani V. Siripala, Yifan Yang, Yvonne Yan Yan Or, Malea Nguyen, Robert Duba-Kiss, Daniel Feng, Laura Williams, Christopher J. Gafuik, GengYi Wang, Chloe Quelin, Boris Keren, Sarah Schuhmann, Georgia Vasileiou, Alexia Bourgois, Antonio Vitobello, Christophe Philippe, Zornitza Stark, Richard J. Leventer, George McGillivray, Frederic Tran Mau-Them, Marine Tessarech, Clément Prouteau, Phillis Lakeman, Mahdi M. Motazacker, Donald R. Latner, Raymond C. Caylor, Yvette van Ierland, Eloise Prijoles, Angie Lichty, Evangelos Theodorou, David A. Sweetser, Edward Steel, Jan Cobben, Majed J. Dasouki, Daniel G. Calame, Bertrand Isidor, Benjamin Cogné, Mitchell Kesler, Brooke Rackel, Isabel Clark, Deborah M. Kurrasch, G. Campbell Teskey, James Ellis, Guiqiong He, Scott D. Ryan, Douglas J. Mahoney, A. Micheil Innes, Jonathan R. Epp, Guang Yang
Abstract
Plasmodium falciparum (Pf) induces the clonal expansion of antigen-specific type 1 regulatory T (Tr1) cells capable of long-term memory. Tr1 cells comprise nearly 90% of the Pf blood stage antigen-specific CD4+ T cell pool in children. Though, whether Tr1 cells contribute to protection from malaria remains undetermined. To address this critical knowledge gap, we first performed scRNA-seq on gated cell populations and validated CXCR6+ CD127– as new phenotypic markers to enrich for bona fide Tr1 cells. Importantly, these Tr1 cells potently suppressed the proliferation of other CD4+ T cells in vitro via IL-10 secretion. Among children living in malaria-endemic Uganda, CXCR6+ CD127– Tr1 cells were the dominant responding subset to Pf-infected red blood cell stimulation in vitro. They also rapidly expanded following malaria and expressed IL-10 and IFN-γ during infection in vivo. Tr1 abundance correlated with plasma concentrations of granzyme A, IFN-γ, IL-10, and LAG3, suggesting that these cells act systemically. Higher CXCR6+ CD127– Tr1 cell frequencies correlated with a lower probability of symptoms given parasitemia but were also associated with delayed parasite clearance among untreated, asymptomatic children. These data suggest that Tr1 cells help mediate clinical immunity to malaria but may also facilitate parasite persistence through mechanisms of immune regulation.
Authors
Jason Nideffer, Florian Bach, Steven Strubbe, Luis Lopez, Maato Zedi, Felistas Nankya, Jessica Briggs, Kattria van der Ploeg, Kenneth Musinguzi, Soyeon Kim, Aracely Garcia Romero, Arefin Keya, Kylie Camanag, Savannah Lewis, Muhammad Abdelbasset, Bing Wang, Allison Boss, Evelyn Nansubuga, Joaniter I. Nankabirwa, Emmanuel Arinaitwe, Saki Takahashi, Grant Dorsey, Bryan Greenhouse, Isabel Rodriguez-Barraquer, Moses R. Kamya, Rosa Bacchetta, Isaac Ssewanyana, Ashraful Haque, Maria Grazia Roncarolo, Prasanna Jagannathan
Abstract
Immune checkpoint blockade (ICB), including PD-1/PD-L1 inhibitors, has transformed cancer therapy but benefits only a subset of patients. Understanding how PD-L1 is regulated and identifying strategies to overcome resistance remain critical. Here, we identify SIRT2 as a key positive regulator of PD-L1 across multiple human cancers. Unexpectedly, SIRT2 did not act at the transcriptional level but stabilized PD-L1 protein by preventing ubiquitin-mediated degradation. Mechanistically, SIRT2 maintained the protein stability of USP22, a PD-L1 deubiquitinase. Loss of SIRT2 reduced USP22 levels, whereas ectopic USP22 fully rescued PD-L1 expression and reversed the enhanced antitumor immunity induced by SIRT2 inhibition. We further show that SIRT2 directly deacetylates USP22 at K382 and K505 within its catalytic domain, promoting USP22 deubiquitinase activity and protecting both itself and its substrates from degradation. Our findings reveal a molecular mechanism by which an acetylation–deacetylation switch dynamically regulates deubiquitinase catalytic activity. Therapeutically, SIRT2 inhibition synergized with PD-1/PD-L1 blockade and USP22 inhibition to enhance antitumor immunity. Consistently, protein, but not mRNA, levels of SIRT2, USP22, and PD-L1 positively correlated in human bladder cancer and melanoma. Together, these findings define a SIRT2/USP22/PD-L1 axis driving tumor immune evasion and highlight SIRT2 as a promising target to improve ICB efficacy.
Authors
Na Li, Qiong Gao, Huijun Jia, Guoqing Xue, Yuanzhang Zhou, Shengnan Wang, Suxian Ma, Bingjin Hu, Zhuoyue Zhao, Chen Su, Yinghong Liu, Wenxuan Xi, Zhonghao Li, Donna D. Zhang, Peng Chu, Zhaolin Sun, Deyu Fang
Abstract
Klinefelter syndrome (KS), the most common sex chromosome aneuploidy (affecting approximately 1 in 650 live male births), causes severe infertility. The extra X chromosome can impair the development of fetal germ cells, but its effects on somatic cells, especially Leydig cells, are still not well known. We performed single-cell RNA-sequencing analysis of fetal KS and control testicular cells and found 2 clusters of KS Sertoli cells, with the XIST-negative cluster showing distinct gene expression pattern and abnormally increased G2/M ratio. Fetal KS Leydig cells showed increased proliferation and immature differentiation with high level of MAPK signaling pathway and X-linked EIF1AX. Inhibition of MAPK signaling partially rescued overproliferation and defective differentiation and androgen secretion in KS Leydig cells, while overexpression of EIF1AX recapitulated the phenotypes of increased proliferation and decline in testosterone synthesis capacity in the Leydig cell line. These findings reveal the early pathological mechanisms of KS somatic cells and lay the groundwork for developing early intervention strategies.
Authors
Tong Yan, Guancheng Chen, Jie Zhang, Wenjing Jia, Nan Lu, Shuping Jin, Haotian Zhang, Yichen Zhao, Lu Jiang, Jing Wu, Qing Liu, Chenghao Situ, Hui Zhu, Yan Li, Quan Wang, Xiaoyu Yang, Chao Qin, Xiaofeng Song, Qing Cheng, Xuejiang Guo
Abstract
Clonal hematopoiesis (CH) is the age-related expansion of mutated hematopoietic stem cells without hematologic abnormalities. In patients with solid tumors, CH is associated with higher mortality and may evolve to therapy-related myeloid neoplasms; however, the mechanisms by which cancer treatments promote CH dynamics remain largely unknown. Here, we analyzed 392 serial samples from a prospective cohort of patients with breast cancer and show that cytotoxic treatments led to strong therapeutic bottlenecks, resulting in significant reductions in hematopoietic allelic populations and differential clonal selection. Positively selected CH that expanded through dose-dependent therapeutic bottlenecks harbored mutations in TP53, PPM1D, SRCAP, DNMT3A, and YLPM1. Patients with positively selected CH during treatment had the shortest progression-free and overall survival compared with patients with unchanging or negatively selected CH across all therapies. These findings, validated in independent breast cancer and pan-cancer cohorts, provide strong evidence for the clinical relevance of monitoring CH during cancer treatment.
Authors
Mona Arabzadeh, Yi-Han Tang, Christelle Colin-Leitzinger, Sadegh Marzban, Daniel Walgenbach, Stefania Morganti, Vaidhyanathan Mahaganapathy, Erika Harper, Mingxiang Teng, Jacob K. Kresovich, Iman Washington, Heather A. Parsons, Judy E. Garber, Jeffrey West, Shridar Ganesan, Hossein Khiabanian, Nancy Gillis
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ISSN: 0021-9738 (print), 1558-8238 (online)