Cell biology
Abstract
Three principal ER quality-control mechanisms, namely, unfolded protein response (UPR), ER-associated degradation (ERAD) and ER-phagy are each important for the maintenance of ER homeostasis, yet how they are integrated to regulate ER homeostasis and organellar architecture in vivo is largely unclear. Here we report intricate crosstalk among the three pathways, centered around the SEL1L-HRD1 protein complex of ERAD, in the regulation of organellar organization in β-cells. SEL1L-HRD1 ERAD deficiency in β-cells triggers activation of autophagy via IRE1α [an endogenous ERAD substrate]. In the absence of functional SEL1L-HRD1 ERAD, proinsulin is retained in the ER as high molecular weight conformers, which are subsequently cleared via ER-phagy. A combined loss of both SEL1L and autophagy in β-cells leads to diabetes in mice shortly after weaning, with premature death by ~11 weeks of age, associated with marked ER retention of proinsulin and β-cell loss. Using focus-ion beam scanning electron microscopy (FIB-SEM) powered by deep-learning automated image segmentation and 3D reconstruction, our data demonstrate a profound organellar restructuring with a massive expansion of ER volume and network in β-cells lacking both SEL1L and autophagy. These data reveal at an unprecedented detail the intimate crosstalk among the three ER quality-control mechanisms in the dynamic regulation of organellar architecture and β-cell function.
Authors
Neha Shrestha, Mauricio Torres, Jason Zhang, You Lu, Leena Haataja, Rachel B. Reinert, Jeffrey Knupp, Yu-Jie Chen, Gunes Parlakgul, Ana Paula Arruda, Billy Tsai, Peter Arvan, Ling Qi
Abstract
Invasive bacterial infections remain a major cause of human morbidity. Group B Streptococcus (GBS) are Gram-positive bacteria that cause invasive infections in humans. Here, we show that Factor XIIIA (FXIIIA) -deficient female mice exhibited significantly increased susceptibility to GBS infections. Additionally, female wild-type mice had increased levels of FXIIIA and were more resistant to GBS infection compared to isogenic male mice. We observed that administration of exogenous FXIIIA to male mice increased host resistance to GBS infection. Conversely, administration of a FXIIIA transglutaminase inhibitor to female mice decreased host resistance to GBS infection. Interestingly, male gonadectomized mice exhibited decreased sensitivity to GBS infection, suggesting a role for gonadal androgens in host susceptibility. FXIIIA promoted GBS entrapment within fibrin clots by crosslinking fibronectin with ScpB, a fibronectin binding GBS surface protein. Thus, ScpB-deficient GBS exhibited decreased entrapment within fibrin clots in vitro and increased dissemination during systemic infections. Finally, using mice where FXIIIA expression was depleted in mast cells, we observed that mast cell derived FXIIIA contributes to host defense against GBS infection. Our studies provide insights into the effect of sexual dimorphism and mast cells on FXIIIA expression and its interactions with GBS adhesins that mediate bacterial dissemination and pathogenesis.
Authors
Adrian M. Piliponsky, Kavita Sharma, Phoenicia Quach, Alyssa Brokaw, Shayla Nguyen, Austyn Orvis, Siddhartha S. Saha, Nyssa Becker Samanas, Ravin Seepersaud, Yu Ping Tang, Emily Mackey, Gauri Bhise, Claire Gendrin, Anna Furuta, Albert J. Seo, Eric Guga, Irina Miralda, Michelle M. Coleman, Erin L. Sweeney, Charlotte A. Bäuml, Diana Imhof, Jessica M. Snyder, Adam J. Moeser, Lakshmi Rajagopal
Abstract
Bone is a common site of metastasis in lung cancer but the regulatory mechanism remains incompletely understood. Osteoclasts are known to play crucial roles in osteolytic bone metastasis by digesting bone matrix and indirectly enhancing tumor colonization. In this study, we found that IL20RB mediated a direct tumoral response to osteoclasts. Tumoral expression of IL20RB was associated with bone metastasis of lung cancer, and functionally IL20RB promoted metastatic growth of lung cancer cells in bone. Mechanistically, tumor cells induced osteoclasts to secrete the IL20RB ligand IL19, and IL19 stimulated IL20RB-expressing tumor cells to activate the downstream JAK1-STAT3 signaling and enhanced proliferation of tumor cells in bone. Importantly, blocking IL20RB with a neutralizing antibody significantly suppressed bone metastasis of lung cancer. Overall, our data revealed a direct pro-tumor role of osteoclastic niche in bone metastasis and supported IL20RB-targeting approaches for metastasis treatment.
Authors
Yunfei He, Wenqian Luo, Yingjie Liu, Yuan Wang, Chengxin Ma, Qiuyao Wu, Pu Tian, Dasa He, Zhenchang Jia, Xianzhe Lv, Yu-Shui Ma, Haitang Yang, Ke Xu, Xue Zhang, Yansen Xiao, Peiyuan Zhang, Yajun Liang, Da Fu, Feng Yao, Guohong Hu
Abstract
The switch from anchorage-dependent to anchorage-independent growth is essential for epithelial metastasis. The underlying mechanism, however, is not fully understood. Here in this study, we identified growth factor independent-1 (GFI1), a transcription factor that drives transition from adherent endothelial cells to suspended hematopoietic cells during hematopoiesis, as a critical regulator of anchorage-independence in lung cancer cells. GFI1 elevated the numbers of circulating and lung infiltrating tumor cells in xenograft models and predicted poor prognosis of lung cancer patients. Mechanistically, GFI1 inhibited the expression of multiple adhesion molecules and facilitated substrate detachment. Concomitantly, GFI1 reconfigured chromatin structure of the RASGRP2 gene and increased its expression, causing Rap1 activation and subsequent sustained ERK activation upon detachment, and this leaded to ERK signaling dependency in tumor cells. Our studies unveiled a mechanism by which carcinoma cells hijacked a hematopoietic factor to gain anchorage independence and suggested that the intervention of ERK signaling may suppress metastasis and improve the therapeutic outcome of GFI1-positive lung cancer patients.
Authors
Hao Wang, Zhenzhen Lin, Zhe Nian, Wei Zhang, Wenxu Liu, Fei Yan, Zengtuan Xiao, Xia Wang, Zhenfa Zhang, Zhenyi Ma, Zhe Liu
Abstract
Lymph node (LN) fibroblastic reticular cells (FRCs) define LN niches and regulate lymphocyte homeostasis through producing diverse extracellular matrix (ECM) components. We examined the role of ECM laminin α4 (Lama4) using FRC-Lama4 conditional KO Pdgfrb-Cre–/– × Lama4fl/fl mice. Single-cell RNA-sequencing (scRNA-Seq) data showed the promoter gene Pdgfrb was exclusively expressed in FRCs. Depleting FRC-Lama4 reduced Tregs and dendritic cells, decreased high endothelial venules, impaired the conduit system, and downregulated T cell survival factors in LNs. FRC-Lama4 depletion impaired the homing of lymphocytes to LNs in homeostasis and after allografting. Alloantigen-specific T cells proliferated, were activated to greater degrees in LNs lacking FRC-Lama4, and were more prone to differentiate into effector phenotypes relative to the Treg phenotype. In murine cardiac transplantation, tolerogenic immunosuppression was not effective in FRC-Lama4 recipients, which produced more alloantibodies than WT. After lung transplantation, FRC-Lama4–KO mice had more severe graft rejection with fewer Tregs in their LNs. Overall, FRC-Lama4 critically contributes to a tolerogenic LN niche by supporting T cell migration, constraining T cell activation and proliferation, and promoting Treg differentiation. Hence, it serves as a therapeutic target for immunoengineering.
Authors
Lushen Li, Marina W. Shirkey, Tianshu Zhang, Wenji Piao, Xiaofei Li, Jing Zhao, Zhongcheng Mei, Yizhan Guo, Vikas Saxena, Allison Kensiski, Samuel J. Gavzy, Yang Song, Bing Ma, Jing Wu, Yanbao Xiong, Long Wu, Xiaoxuan Fan, Holly Roussey, Meng Li, Alexæander S. Krupnick, Reza Abdi, Jonathan S. Bromberg
Abstract
Maladaptive changes of nerve injury–associated genes in dorsal root ganglia (DRGs) are critical for neuropathic pain genesis. Emerging evidence supports the role of long noncoding RNAs (lncRNAs) in regulating gene transcription. Here we identified a conserved lncRNA, named nerve injury–specific lncRNA (NIS-lncRNA) for its upregulation in injured DRGs exclusively in response to nerve injury. This upregulation was triggered by nerve injury–induced increase in DRG ELF1, a transcription factor that bound to the NIS-lncRNA promoter. Blocking this upregulation attenuated nerve injury–induced CCL2 increase in injured DRGs and nociceptive hypersensitivity during the development and maintenance periods of neuropathic pain. Mimicking NIS-lncRNA upregulation elevated CCL2 expression, increased CCL2-mediated excitability in DRG neurons, and produced neuropathic pain symptoms. Mechanistically, NIS-lncRNA recruited more binding of the RNA-interacting protein FUS to the Ccl2 promoter and augmented Ccl2 transcription in injured DRGs. Thus, NIS-lncRNA participates in neuropathic pain likely by promoting FUS-triggered DRG Ccl2 expression and may be a potential target in neuropathic pain management.
Authors
Shibin Du, Shaogen Wu, Xiaozhou Feng, Bing Wang, Shangzhou Xia, Lingli Liang, Li Zhang, Gokulapriya Govindarajalu, Alexander Bunk, Feni Kadakia, Qingxiang Mao, Xinying Guo, Hui Zhao, Tolga Berkman, Tong Liu, Hong Li, Jordan Stillman, Alex Bekker, Steve Davidson, Yuan-Xiang Tao
Abstract
Acquired resistance is inevitable in non-small cell lung cancers (NSCLCs) treated with osimertinib (OSI), and the mechanisms are not well defined. The MERTK ligand GAS6 promoted downstream oncogenic signaling in EGFR-mutated (EGFRMT) NSCLC cells treated with OSI, suggesting a role for MERTK activation in OSI resistance. Indeed, treatment with MRX-2843, a first-in-class MERTK kinase inhibitor, re-sensitized GAS6-treated NSCLC cells to OSI. Both GAS6 and EGF stimulated downstream PI3K-AKT and MAPK-ERK signaling in parental cells, but only GAS6 activated these pathways in OSI resistant (OSIR) derivative cell lines. Functionally, OSIR cells were more sensitive to MRX-2843 than parental cells, suggesting acquired dependence on MERTK signaling. Furthermore, MERTK and/or its ligands were dramatically upregulated in EGFRMT tumors after treatment with OSI in both xenograft models and patient samples, consistent with induction of autocrine/paracrine MERTK activation. Moreover, treatment with MRX-2843 in combination with OSI, but not OSI alone, provided durable suppression of tumor growth in vivo, even after treatment was stopped. These data identify MERTK as a driver of bypass signaling in treatment-naïve and EGFRMT-OSIR NSCLC cells and predict that MRX-2843 and OSI combination therapy will provide clinical benefit in patients with EGFRMT NSCLC.
Authors
Dan Yan, Justus M. Huelse, Dmitri Kireev, Zikang Tan, Luxiao Chen, Subir Goyal, Xiaodong Wang, Stephen V. Frye, Madhusmita Behera, Frank Schneider, Suresh S. Ramalingam, Taofeek K. Owonikoko, H. Shelton Earp, Deborah DeRyckere, Douglas K. Graham
Abstract
The crosstalk between the BM microenvironment (niche) and hematopoietic stem cells (HSCs) is critical for HSC regeneration. Here, we show that in mice, deletion of the Fanconi anemia (FA) genes Fanca and Fancc dampened HSC regeneration through direct effects on HSCs and indirect effects on BM niche cells. FA HSCs showed persistent upregulation of the Wnt target Prox1 in response to total body irradiation (TBI). Accordingly, lineage-specific deletion of Prox1 improved long-term repopulation of the irradiated FA HSCs. Forced expression of Prox1 in WT HSCs mimicked the defective repopulation phenotype of FA HSCs. WT mice but not FA mice showed significant induction by TBI of BM stromal Wnt5a protein. Mechanistically, FA proteins regulated stromal Wnt5a expression, possibly through modulating the Wnt5a transcription activator Pax2. Wnt5a treatment of irradiated FA mice enhanced HSC regeneration. Conversely, Wnt5a neutralization inhibited HSC regeneration after TBI. Wnt5a secreted by LepR+CXCL12+ BM stromal cells inhibited β-catenin accumulation, thereby repressing Prox1 transcription in irradiated HSCs. The detrimental effect of deregulated Wnt5a/Prox1 signaling on HSC regeneration was also observed in patients with FA and aged mice. Irradiation induced upregulation of Prox1 in the HSCs of aged mice, and deletion of Prox1 in aged HSCs improved HSC regeneration. Treatment of aged mice with Wnt5a enhanced hematopoietic repopulation. Collectively, these findings identified the paracrine Wnt5a/Prox1 signaling axis as a regulator of HSC regeneration under conditions of injury and aging.
Authors
Qiqi Lin, Limei Wu, Srinivas Chatla, Fabliha A. Chowdhury, Neha Atale, Jonathan Joseph, Wei Du
Abstract
Mitochondrial stress triggers a response in the cell’s mitochondria and nucleus, but how these stress responses are coordinated in vivo is poorly understood. Here, we characterize a family with myopathy caused by a dominant p.G58R mutation in the mitochondrial protein CHCHD10. To understand the disease etiology, we developed a knock-in mouse model and found that mutant CHCHD10 aggregates in affected tissues, applying a toxic protein stress to the inner mitochondrial membrane. Unexpectedly, survival of CHCHD10 knock-in mice depended on a protective stress response mediated by OMA1. The OMA1 stress response acted both locally within mitochondria, causing mitochondrial fragmentation, and signaled outside the mitochondria, activating the integrated stress response through cleavage of DELE1. We additionally identified an isoform switch in the terminal complex of the electron transport chain as a component of this response. Our results demonstrate that OMA1 is critical for neonatal survival conditionally in the setting of inner mitochondrial membrane stress, coordinating local and global stress responses to reshape the mitochondrial network and proteome.
Authors
Mario K. Shammas, Xiaoping Huang, Beverly P. Wu, Evelyn Fessler, Insung Song, Nicholas P. Randolph, Yan Li, Christopher K.E. Bleck, Danielle A. Springer, Carl Fratter, Ines A. Barbosa, Andrew F. Powers, Pedro M. Quirós, Carlos Lopez-Otin, Lucas T. Jae, Joanna Poulton, Derek P. Narendra
Abstract
Mitochondrial proteostasis, regulated by the mitochondrial unfolded protein response (UPRmt), is crucial for maintenance of cellular functions and survival. Elevated oxidative and proteotoxic stress in mitochondria must be attenuated by the activation of ubiquitous UPRmt to promote prostate cancer (PCa) growth. Here we show that the two key components of the UPRmt, heat shock protein 60 (HSP60, a mitochondrial chaperonin) and caseinolytic protease (ClpP, a mitochondrial protease) were required for the development of advanced PCa. HSP60 regulated ClpP expression via c-Myc and physically interacted with ClpP to restore mitochondrial functions promoting cancer cell survival. HSP60 maintained the ATP-producing functions of mitochondria, which activated β-catenin pathway leading to the upregulation of c-Myc. We identified an UPRmt inhibitor that blocked HSP60 interaction with ClpP and abrogated survival signaling without altering HSP60 chaperonin function. Disruption of HSP60-ClpP interaction by UPRmt inhibitor triggered metabolic stress and impeded PCa promoting signaling. Treatment with UPRmt inhibitor, or genetic ablation of Hsp60, inhibited PCa growth and progression. Together, our findings identify that HSP60-ClpP mediated UPRmt is essential for prostate tumorigenesis and HSP60-ClpP interaction represents a therapeutic vulnerability in PCa.
Authors
Rahul Kumar, Ajay Kumar Chaudhary, Jordan Woytash, Joseph R. Inigo, Abhiram A. Gokhale, Wiam Bshara, Kristopher Attwood, Jianmin Wang, Joseph A. Spernyak, Eva Rath, Neelu Yadav, Dirk Haller, David W. Goodrich, Dean G. Tang, Dhyan Chandra
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ISSN: 0021-9738 (print), 1558-8238 (online)