Cell biology
Abstract
Lineage plasticity is recognized as a critical determinant of lethality and resistance to AR pathway inhibitors in prostate cancer. Lineage plasticity is a continuum, ranging from AR activity-low tumors, AR-null tumors that do not express a neuroendocrine prostate cancer (NEPC) program (i.e., double-negative prostate cancer [DNPC]), and AR-null NEPC tumors. Factors upregulated early in lineage plasticity are not well-characterized. The clarification of such factors is essential to identify tumors undergoing lineage plasticity or at risk of this occurring. Our integrative analysis of metastatic prostate cancer patient tumors, patient-derived xenografts, and cell models determined that PROX1 is upregulated early in the lineage plasticity continuum and progressively increases as tumors lose AR activity. We determined DNA methylation is a key regulator of PROX1 expression. PROX1 suppression in DNPC and NEPC reduces cell survival and impacts apoptosis and differentiation, demonstrating PROX1’s functional importance. PROX1 is not directly targetable with standard drug development approaches. However, affinity immunopurification demonstrated histone deacetylases (HDACs) are among the top PROX1-interacting proteins; HDAC inhibition depletes PROX1 and recapitulates PROX1 suppression in DNPC and NEPC. Altogether, our results suggest PROX1 promotes the emergence of lineage plasticity, and HDAC inhibition is a promising approach to treat tumors across the lineage plasticity continuum.
Authors
Zhi Duan, Mingchen Shi, Anbarasu Kumaraswamy, Dong Lin, Dhruv Khokhani, Yong Wang, Chao Zhang, Diana Flores, Eva Rodansky, Olivia A. Swaim, William K. Storck, Hannah N. Beck, Radhika A. Patel, Erolcan Sayar, Brian P. Hanratty, Hui Xue, Xin Dong, Zoe R. Maylin, Rensheng Wan, David A. Quigley, Martin Sjöström, Ya-Mei Hu, Faming Zhao, Zheng Xia, Siyuan Cheng, Xiuping Yu, Felix Y. Feng, Li Zhang, Rahul Aggarwal, Eric J. Small, Visweswaran Ravikumar, Arvind Rao, Karan Bedi, John K. Lee, Colm Morrissey, Ilsa Coleman, Peter S. Nelson, Eva Corey, Aaron M. Udager, Ryan J. Rebernick, Marcin P. Cieslik, Arul M. Chinnaiyan, Joel A. Yates, Michael C. Haffner, Yuzhuo Wang, Joshi J. Alumkal
Abstract
Loss-of-function mutations in genome maintenance genes fuel tumorigenesis through increased genomic instability. A subset of these tumor suppressors are challenging to identify due to context dependency, including functional interactions with other genes and pathways. Here, we searched for potential causal genes that impact tumor development and/or progression in breast cancer through functional-genetic screening of candidate genes. MYH4, encoding a class II myosin, emerged as a top hit impacting genomic stability. We show that MYH4 suppresses DNA replication stress by promoting replication licensing and replication fork progression. Moreover, we observed a strong synergistic relationship among class II myosins in suppressing replication-associated DNA damage. Genomic analysis of Pan-Cancer Analysis of Whole Genomes project breast cancer samples revealed frequent concomitant loss of TP53 with MYH4 and class II myosins on chromosome 17p. Notably, Myh4 disruption accelerated mouse mammary tumorigenesis in a Trp53-deficient background. In conclusion, our results suggest an unanticipated function of MYH4 in p53-mediated tumor suppression that can explain their combined loss in breast cancer.
Authors
Jayashree Thatte, Ana Moisés da Silva, Judit Börcsök, Thorkell Gudjónsson, Jan Benada, Xin Li, Muthiah Bose, Hanneke van der Gulden, Ji-Ying Song, Renée Menezes, Elena Martín-Doncel, Luis Toledo, Valdemaras Petrosius, Cord Brakebusch, Jos Jonkers, Finn Cilius Nielsen, Maria Rossing, Claus S. Sørensen
Abstract
Glycogenolysis and gluconeogenesis ensure sufficient hepatic glucose production during energy shortages. Here, we report that hepatic glycogen levels control the phosphorylation of a transcriptional coactivator to determine the amplitude of gluconeogenesis. Decreased liver glycogen during fasting promotes gluconeogenic gene expression, while feeding-induced glycogen accumulation suppresses it. Liver-specific deletion of the glycogen scaffolding protein, protein targeting to glycogen (PTG), reduces glycogen levels, increases the expression of gluconeogenic genes, and promotes glucose production in primary hepatocytes. In contrast, liver glycogen phosphorylase (PYGL) knockdown or inhibition increases glycogen levels and represses gluconeogenic gene expression. These changes in hepatic glycogen levels are sensed by AMP-activated protein kinase (AMPK). AMPK activity is increased when glycogen levels decline, resulting in the phosphorylation and stabilization of CREB-regulated transcriptional coactivator 2 (CRTC2), which is crucial for the full activation of the cAMP-responsive transcriptional factor CREB. High glycogen allosterically inhibits AMPK, leading to CRTC2 degradation and reduced CREB transcriptional activity. Hepatocytes with low glycogen levels or high AMPK activity show higher CRTC2 protein levels, priming the cell for gluconeogenesis through transcriptional regulation. Thus, glycogen plays a regulatory role in controlling hepatic glucose metabolism through the glycogen/AMPK/CRTC2 signaling axis, safeguarding efficient glucose output during fasting and suppressing it during feeding.
Authors
Bichen Zhang, Morgan M. Johnson, Timothy Yuan, Tammy-Nhu Nguyen, Junichi Okada, Fajun Yang, Alus M. Xiaoli, Liana H. Melikian, Songran Xu, Benyamin Dadpey, Jeffrey E. Pessin, Alan R. Saltiel
Abstract
Anemia is the primary clinical manifestation of myelodysplastic syndromes (MDS), but the molecular pathogenesis of ineffective erythropoiesis remains incompletely understood. Luspatercept, an activin receptor 2B (ACVRIIB-Fc) ligand trap, has been approved to treat anemia, however its molecular mechanism of action is unclear. We found that the ACVR2B, its ligand GDF11, and effector, SMAD2, are upregulated in MDS patient samples. GDF11 inhibited human erythropoiesis in vitro and caused anemia in zebrafish, effects that were abrogated by luspatercept. Upon GDF11 stimulation of human erythroid progenitors, SMAD2 binding occurred in the erythroid regulatory regions, including at GATA1 intron. Intronic SMAD2 binding led to skipping of exon 2 of GATA1, resulting in a shorter, hypomorphic isoform (GATA1s). CRISPR deletion of the SMAD2 binding intronic region decreased GATA1s production upon GDF11 stimulation. Expression of gata1s in a mouse model led to anemia, rescued by a murine ActRIIB-Fc (RAP-536). Finally, RNA-seq analysis of samples from the Phase 3 MEDALIST trial revealed that responders to Luspatercept had a higher proportion of GATA1s compared to non-responders. Moreover, the increase RBCs post-treatment was linked to a relative decrease in GATA1s isoform. Our study indicates that GDF11-mediated SMAD2 activation results in an increase in functionally impaired GATA1 isoforms, consequently contributing to anemia and influencing responses to Luspatercept in MDS.
Authors
Srinivas Aluri, Te Ling, Ellen Fraint, Samarpana Chakraborty, Kevin Zhang, Aarif Ahsan, Leah Kravets, Gowri Poigaialwar, Rongbao Zhao, Kith Pradhan, Anitria Cotton, Kimo Bachiashvili, Jung-In Yang, Anjali Budhathoki, Beamon Agarwal, Shanisha Gordon-Mitchell, Milagros Carbajal, Srabani Sahu, Jacqueline Boultwood, Andrea Pellagatti, Ulrich Steidl, Amittha Wickrema, Satish Nandakumar, Aditi Shastri, Rajasekhar N.V.S. Suragani, Teresa V. Bowman, John D. Crispino, Sadanand Vodala, Amit Verma
Abstract
Air pollution is a serious environmental threat to public health; however, the molecular basis underlying its detrimental effects on respiratory fitness remains poorly understood. Here, we show that exposure to particulate matter ≤2.5 µm (PM2.5), a significant fraction of air pollutants, induces the generation of reactive aldehyde species in the airway. We identified aldehyde dehydrogenase 1A1 (ALDH1A1), which is selectively expressed in airway epithelium, as an enzyme responsible for detoxifying these reactive aldehyde species. Loss of ALDH1A1 function results in the accumulation of aldehyde adducts in the airway, which selectively impairs mucociliary clearance (MCC), a critical defense mechanism against respiratory pathogens. Thus, ALDH1A1-deficient mice pre-exposed to PM2.5 exhibited increased susceptibility to pneumonia. Conversely, pharmacological enhancement of ALDH1A1 activity promoted the restoration of MCC function. These findings elucidate the critical role of aldehyde metabolism in protecting against PM2.5 exposure, offering a potential target to mitigate the negative health consequences of air pollution.
Authors
Noriko Shinjyo, Haruna Kimura, Tomomi Yoshihara, Jun Suzuki, Masaya Yamaguchi, Shigetada Kawabata, Yasutaka Okabe
Abstract
Germinal centre (GC) B cells are pivotal in establishing a robust humoral immune response and long-term serological immunity while maintaining antibody self-tolerance. GC B cells rely on autophagy for antigen presentation and homeostatic maintenance. However, these functions, primarily associated with the light zone, cannot explain the spatiotemporal autophagy upregulation in the dark zone of GCs. Here, we define a functional mechanism controlling chromatin accessibility in GC B cells during their dark zone transition. This mechanism links autophagy and nuclear Lamin B1 dynamics with their downstream effects, including somatic hypermutation and antibody affinity maturation. Moreover, the autophagy-Lamin B1 axis is highly active in the aberrant ectopic germinal centres in the salivary glands of Sjogren’s disease, defining its role in autoimmunity.
Authors
Marta C Sallan, Filip Filipsky, Christina H. Shi, Elena Pontarini, Manuela Terranova-Barberio, Gordon Beattie, Andrew Clear, Michele Bombardieri, Kevin Y. Yip, Dinis Parente Calado, Mark S. Cragg, Sonya James, Matthew J. Carter, Jessica Okosun, John G. Gribben, Tanya Klymenko, Andrejs Braun
Abstract
Mitral valve prolapse is often benign but progression to mitral regurgitation may require invasive intervention and there is no specific medical therapy. An association of mitral valve prolapse with Marfan syndrome resulting from pathogenic FBN1 variants supports the use of hypomorphic fibrillin-1 mgR mice to investigate mechanisms and therapy for mitral valve disease. mgR mice developed severe myxomatous mitral valve degeneration with mitral regurgitation by 12 weeks of age. Persistent activation of TGF-β and mTOR signaling along with macrophage recruitment preceded histological changes at 4 weeks of age. Short-term mTOR inhibition with rapamycin from 4 to 5 weeks of age prevented TGF-β overactivity and leukocytic infiltrates, while long-term inhibition of mTOR or TGF-β signaling from 4 to 12 weeks of age rescued mitral valve leaflet degeneration. Transcriptomic analysis identified integrins as key receptors in signaling interactions and serologic neutralization of integrin signaling or a chimeric integrin receptor altering signaling prevented mTOR activation. We confirmed increased mTOR signaling and a conserved transcriptome signature in human specimens of sporadic mitral valve prolapse. Thus, mTOR activation from abnormal integrin-dependent cell-matrix interactions drives TGF-β overactivity and myxomatous mitral valve degeneration, and mTOR inhibition may prevent disease progression of mitral valve prolapse.
Authors
Fu Gao, Qixin Chen, Makoto Mori, Sufang Li, Giovanni Ferrari, Markus Krane, Rong Fan, George Tellides, Yang Liu, Arnar Geirsson
Abstract
Glycosylation controls immune evasion, tumor progression, and metastasis. However, how tumor cell sialylation regulates immune evasion remains poorly characterized. ST6GalNAc-I, a sialyltransferase that conjugates sialic acid to the glycans in glycoproteins, was overexpressed in an aggressive-type KPA (KrasG12D/+ Trp53R172H/+ Ad-Cre) lung adenocarcinoma (LUAD) model and patient samples. Proteomic and biochemical analysis indicated that ST6GalNAc-I mediated NECTIN2 sialylation in LUAD cells. ST6GalNAc-I–deficient tumor cells cocultured with T cells were more susceptible to T cell–mediated tumor cell killing, indicating a key role for NECTIN2 in T cell dysfunction. Mice injected with St6galnac-I–knockdown syngeneic cells showed reduced lung tumor incidence and Nectin2/Tigit-associated immunosuppression. ST6GalNAc-I–deficient cells exhibited reduced P-DMEA metabolite levels, while administration of P-DMEA promoted LUAD cell proliferation via MUC5AC. MUC5AC interacted and colocalized with PRRC1 in the Golgi, suggesting a potential role for PRRC1 in MUC5AC glycosylation. Mice injected with ST6GalNAc-I/MUC5AC-deficient cells (human LUAD) exhibited reduced lung tumor incidence, angiogenesis, and liver metastases. Mechanistically, ST6GalNAc-I/MUC5AC regulates VCAN-V1, a key factor in tumor matrix remodeling during angiogenesis and metastasis. These findings demonstrate that ST6GalNAc-I–mediated sialylation of NECTIN2/MUC5AC is critical for immune evasion and tumor angiogenesis. Targeting this pathway may prevent LUAD development and/or metastasis.
Authors
Muthamil Iniyan Appadurai, Sanjib Chaudhary, Ashu Shah, Gopalakrishnan Natarajan, Zahraa W. Alsafwani, Parvez Khan, Dhananjay D. Shinde, Subodh M. Lele, Lynette M. Smith, Mohd Wasim Nasser, Surinder Kumar Batra, Apar Kishor Ganti, Imayavaramban Lakshmanan
Abstract
Autosomal Dominant Optic Atrophy (ADOA), the most prevalent hereditary optic neuropathy, leads to retinal ganglion cell (RGC) degeneration and vision loss. ADOA is primarily caused by mutations in the OPA1 gene, which encodes a conserved GTPase important for mitochondrial inner membrane dynamics. To date, the disease mechanism remains unclear, and no therapies are available. We generated a mouse model carrying the pathogenic Opa1R290Q/+ allele that recapitulated key features of human ADOA, including mitochondrial defects, age-related RGC loss, optic nerve degeneration, and reduced RGC functions. We identified SARM1, a neurodegeneration switch, as a key driver of RGC degeneration in these mice. Sarm1 knockout nearly completely suppressed all the degeneration phenotypes without reversing mitochondrial fragmentation. Additionally, we showed that a portion of SARM1 localized within the mitochondrial intermembrane space (IMS). These findings indicated that SARM1 was activated downstream of mitochondrial dysfunction in ADOA, highlighting it as a promising therapeutic target.
Authors
Chen Ding, Papa S. Ndiaye, Sydney R. Campbell, Michelle Y. Fry, Jincheng Gong, Sophia R. Wienbar, Whitney Gibbs, Philippe Morquette, Luke H. Chao, Michael Tri H. Do, Thomas Schwarz
Abstract
The activated JAK2/STAT pathway is characteristic of myeloproliferative neoplasms (MPNs). Pleckstrin-2 (PLEK2) signalosome is downstream of the JAK2/STAT5 pathway and plays an important role in MPN development. The detailed molecular composition of this signalosome is unclear. Here, we revealed peptidylprolyl isomerase-like 2 (PPIL2) as a critical component of the complex in regulating human and murine erythropoiesis. PPIL2 was a direct target of STAT5 and was upregulated in MPN patients and a Jak2V617F MPN mouse model. Mechanistically, PPIL2 interacted with and catalyzed p53 polyubiquitination and proteasome-mediated degradation to promote cell growth. Ppil2 deficiency, or inhibition by cyclosporin A, led to a marked upregulation of p53 in vivo and ameliorated myeloproliferative phenotypes in Jak2V617F mice. Cyclosporin A also markedly reduced JAK2 mutated erythroid and myeloid proliferation in an induced pluripotent stem cell-derived human bone marrow organoid model. Our findings revealed PPIL2 as a critical component of the PLEK2 signalosome in driving MPN pathogenesis through negatively regulating p53, thus providing a target and an opportunity for drug repurposing by using cyclosporin A to treat MPNs.
Authors
Pan Wang, Xu Han, Kehan Ren, Ermin Li, Honghao Bi, Inci Aydemir, Madina Sukhanova, Yijie Liu, Jing Yang, Peng Ji
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ISSN: 0021-9738 (print), 1558-8238 (online)