Cell biology
Abstract
Mutations in genome maintenance factors drive sporadic and hereditary breast cancers. Here, we searched for potential drivers based on germline DNA analysis from a cohort consisting of early-onset breast cancer patients negative for BRCA1/BRCA2 mutations. This revealed candidate genes that subsequently were subjected to RNAi-based phenotype screens to reveal genome integrity impacts. We identified several genes with functional roles in genome maintenance, including Glucose-6-Phosphatase Catalytic Subunit 3 (G6PC3), SMC4, and CCDC108. Notably, G6PC3-deficient cells exhibited increased levels of γH2AX and micronuclei formation, along with defects in homologous recombination (HR) repair. Consistent with these observations, G6PC3 was required for the efficient recruitment of BRCA1 to sites of DNA double-strand breaks (DSBs). RNA sequencing analysis revealed that G6PC3 promotes the expression of multiple homologous recombination repair genes, including BRCA1. Through CRISPR-Select functional-genetic phenotype analysis of G6PC3 germline mutations, we identified two germline G6PC3 variants displaying partial loss-of-function. Furthermore, our study demonstrated that G6pc3 deficiency accelerates mammary tumor formation induced by Trp53 loss in mice. In conclusion, our cohort-based functional analysis has unveiled genome maintenance factors and identified G6PC3 as a potential candidate tumor suppressor in breast cancer.
Authors
Xin Li, Maria Rossing, Ana Moisés da Silva, Muthiah Bose, Thorkell Gudjónsson, Jan Benada, Jayashree Thatte, Jens Vilstrup Johansen, Judit Börcsök, Hanneke van der Gulden, Ji-Ying Song, Renée Menezes, Asma Tajik, Lucía Sena, Zoltan Szallasi, Morten Frödin, Jos Jonkers, Finn Cilius Nielsen, Claus Storgaard Sørensen
Abstract
The role of gamma-delta T (γδT) cells in immune responses to common allergens is poorly understood. Here, we utilized single-cell (sc) transcriptomic analysis of allergen-reactive γδT cells in humans to characterize the transcriptional landscapes and TCR repertoires in response to cockroach (CR) and mouse (MO) allergens. Using a novel Activation-Induced Marker (AIM) assay that allows detection of γδT cells combined with scRNA sequencing and TCR repertoire analysis, we identified both shared and allergen-specific γδT cell activation patterns and gene expression profiles. While CR extract activated both Vδ1 and Vδ2 subsets, MO extract primarily stimulated Vδ2 cells. Our analysis revealed allergen-specific clusters with distinct functional signatures, including enhanced inflammatory responses and cytotoxic effector functions in MO-specific γδT cells and natural killer cell-mediated immunity and IFNγ signaling in CR-specific populations. Comparison of allergic and non-allergic individuals highlighted differences in gene expression and TCR repertoires, including a higher IFNG expression in the CR-allergic compared to non-allergic cohorts, suggesting that phenotypic and functional differences are associated with γδT allergen responses. This study provides insights into the cellular and molecular heterogeneity and functionality of allergen-reactive γδT cells, offering a foundation for understanding their role in allergic diseases and potential therapeutic interventions
Authors
Kendall Kearns, Sloan A. Lewis, Esther Dawen Yu, Adam Abawi, Eric Wang, Synaida Maiche, Monalisa Mondal, Pandurangan Vijayanand, Grégory Seumois, Bjoern Peters, Alessandro Sette, Ricardo Da Silva Antunes
Abstract
The dietary sodium-to-potassium ratio is positively correlated with blood pressure, and understanding this relationship is crucial for improving hypertension treatment. Moreover, few studies have examined these effects in both sexes. In this study, we aimed to investigate how supplementing (1.41% K+; HK) or depleting (DK) dietary potassium affects the development of salt-sensitive (SS) hypertension in male and female Dahl SS rats. Potassium supplementation attenuated blood pressure during 5 weeks of high salt (4% NaCl) diet in male but not in female rats. In contrast, potassium-deficient diet prevented the development of SS hypertension in both sexes, though this effect is unlikely to be protective. Both males and females on the DK diet were hypokalemic, had diminished heart rates, reduced weight gain, and females experienced high mortality. Males and females on the DK diet excreted less urinary sodium, but only females had elevated plasma sodium. Additionally, male and female DK-fed rats showed a decrease in multiple metabolites from the renin-angiotensin-aldosterone system. RNA-Sequencing of kidney cortical tissue revealed a number of genes that may underlie the sex-specific differences in phenotype. Analysis of renal ion channel and transporter expression revealed significant increases in basolateral inwardly rectifying potassium channels in DK rats. Male rats supplemented with potassium exhibited a decreased number and size of WNK4 puncta, whereas in potassium-supplemented females, there was no difference in puncta count and an increase in puncta size. Our data indicates there are sex-dependent differences in response to dietary potassium and that the distal nephron compensates for severe potassium deficiency.
Authors
Adrian Zietara, Lashodya V. Dissanayake, Melissa Lowe, Biyang Xu, Vladislav Levchenko, Vasundhara Kain, Ganesh V. Halade, Christine A. Klemens, Oleg Palygin, Alexander Staruschenko
Abstract
Achondroplasia (ACH) and hypochondroplasia (HCH), the two most common types of dwarfism, are each caused by FGFR3 gain-of-function mutations that result in increased FGFR3 signaling, disrupting chondrogenesis and osteogenesis resulting in disproportionately shortened long bones. In this study, TYRA-300, a potent and selective FGFR3 inhibitor, was evaluated in three genetic contexts: wild-type mice, the Fgfr3Y367C/+ mouse model of ACH, and the Fgfr3N534K/+ mouse model of HCH. In each model, TYRA-300 treatment increased naso-anal length, tibia and femur length. In the two FGFR3-altered models, TYRA-300-induced growth partially restored the disproportionality of long bones. Histologic analysis of the growth plate in Fgfr3Y367C/+ mice revealed that TYRA-300 mechanistically increased both proliferation and differentiation of chondrocytes. Importantly, children with ACH can experience medical complications due to foramen magnum stenosis, and TYRA-300 significantly improved the size and shape of the skull and foramen magnum in Fgfr3Y367C/+ mice. Spinal stenosis is also a frequent complication, and TYRA-300 increased the lumbar vertebrae length and improved the shape of the intervertebral discs in both models. Taken together, these studies demonstrate that the selective FGFR3 inhibitor TYRA-300 led to a significant increase in bone growth in two independent FGFR3-driven preclinical models as well as in wild-type mice.
Authors
Jacqueline H. Starrett, Clara Lemoine, Matthias Guillo, Chantal Fayad, Nabil Kaci, Melissa Neal, Emily Pettitt, Melissandre Pache, Qing Ye, My Chouinard, Eric L. Allen, Geneviève Baujat, Robert L. Hudkins, Michael B. Bober, Todd Harris, Ronald V. Swanson, Laurence Legeai-Mallet
Abstract
Dipeptidase-1 (DPEP1) is highly upregulated in colorectal cancer (CRC), with its enzymatic function linked to invasion and metastasis. More recently, DPEP1 was found to serve as a receptor for neutrophils when expressed by activated endothelial cells. It is unknown whether neutrophils bind to DPEP1-expressing CRC cells and whether this impacts features of CRC. Neutrophils have been shown to be tumor-promoting in cancers including CRC, where they act to exclude CD8+ T cells. Herein, we show that neutrophils bind DPEP1-expressing CRC cells. In addition, DPEP1 is preferentially expressed in microsatellite stable (MSS) CRC, in which there are a paucity of CD8+ T cells, whereas DPEP1 is negatively correlated with microsatellite unstable (MSI-H) CRC, which are T cell-rich and are more responsive to immunotherapy. Remarkably, carcinogen-treated Dpep1 null mice develop multiple, large, plaque-like, locally invasive adenocarcinomas and squamous cell cancers in the distal colon. These adenocarcinomas exhibit a marked reduction of neutrophils and an influx CD8+ T cells, along with reduced expression of mismatch repair proteins, consistent with features of MSI-H CRC. These results establish DPEP1’s importance in maintaining MSS CRC and its ability to shape the tumor microenvironment.
Authors
Sarah E. Glass, Matthew E. Bechard, Zheng Cao, Radhika Aramandla, Ping Zhao, Samuel T. Ellis, Emily H. Green, Elizabeth G. Fisher, Ryan T. Smith, Chelsie K. Sievers, Maria Johnson Irudayam, Frank Revetta, M. Kay Washington, Gregory D. Ayers, Cody N. Heiser, Alan J. Simmons, Yanwen Xu, Yu Wang, Annika Windon, Martha J. Shrubsole, Nicholas O. Markham, Qi Liu, Ken S. Lau, Robert J. Coffey
Abstract
Non–small cell lung cancer (NSCLC) is a common cause of cancer-related deaths worldwide, and its incidence has been increasing in recent years. While targeted therapies like osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor, have brought about notable improvements in patient outcomes for advanced NSCLC, the challenge of acquired drug resistance persists. Here, we found that cellular mesenchymal-epithelial transition factor (c-Met) was highly expressed in osimertinib-resistant cells, and depletion of c-Met markedly inhibited the growth of osimertinib-resistant cells ex vivo and in vivo, suggesting that c-Met is a potential target to address osimertinib resistance. Through a screening process using a natural product compound library, we identified piperlongumine as a potent inhibitor to overcome osimertinib resistance. Furthermore, the combined treatment of piperlongumine and osimertinib exhibited robust antitumor effects in resistant cells, partially restoring their sensitivity to osimertinib. Additionally, we discovered that piperlongumine could enhance the interaction between E3 ligase RNF4 and Sp1, inhibit the phosphorylation of Sp1 at Thr739, facilitate the ubiquitination and degradation of Sp1, lead to c-Met destabilization, and trigger intrinsic apoptosis in resistant cells. In summary, our study sheds light on the potential of piperlongumine in overcoming osimertinib resistance, offering new strategies and perspectives for the clinical management of drug-resistant NSCLC.
Authors
Ruirui Wang, Qiang Wang, Jinzhuang Liao, Xinfang Yu, Wei Li
Abstract
The osteo-oto-hepato-enteric (O2HE) syndrome is a severe autosomal recessive disease ascribed to loss-of-function mutations in the Unc-45 myosin chaperone A (UNC45A) gene. The clinical spectrum includes bone fragility, hearing loss, cholestasis, and life-threatening diarrhea associated with microvillus inclusion disease–like enteropathy. Here, we present molecular and functional analysis of the UNC45A c.710T>C (p.Leu237Pro) missense variant, which revealed a unique pathogenicity compared with other genetic variants causing UNC45A deficiency. The UNC45A p.Leu237Pro mutant retained chaperone activity, prevented myosin aggregation, and supported proper nonmuscle myosin II (NMII) filament formation in patient fibroblasts and human osteosarcoma (U2OS) cells. However, the mutant formed atypically stable oligomers and prevented chaperone-myosin complex dissociation, thereby inhibiting NMII functions. Similar to biallelic UNC45A deficiency, this resulted in impaired intracellular trafficking, defective recycling, and abnormal retention of transferrin at various endocytic sites. In particular, coexpression of wild-type protein attenuated the pathogenic effects of the variant by inhibiting excessive oligomer formation. Our results elucidate the pathogenic mechanisms and recessive characteristics of this variant and may aid in the development of targeted therapies.
Authors
Stephanie Waich, Karin Kreidl, Julia Vodopiutz, Arzu Meltem Demir, Adam R. Pollio, Vojtěch Dostál, Kristian Pfaller, Marianna Parlato, Nadine Cerf-Bensussan, Rüdiger Adam, Georg F. Vogel, Holm H. Uhlig, Frank M. Ruemmele, Thomas Müller, Michael W. Hess, Andreas R. Janecke, Lukas A. Huber, Taras Valovka
Abstract
Mitogen-activated protein kinase 8 interacting protein 3 (MAPK8IP3/JIP3) is a member of the kinesin family known to play a role in axonal transport of cargo. Mutations in the gene have been linked to severe neurodevelopmental disorders, resulting in developmental delay, intellectual disability, ataxia, tremor, autism, seizures, and visual impairment. A patient who has a missense mutation in the MAPK8IP3 gene (c. 1714 C>T, Arg578Cys) (R578C) manifests dystonia, gross motor delay and developmental delay. Here we show that the mutation is a toxic gain of function mutation which alters the interactome of JIP3, disrupts axonal transport of late endosomes, increases signaling via c-Jun N-terminal kinase (JNK), resulting in apoptosis, and disrupts the dopamine receptor 1 (D1) signaling while not affecting the dopamine receptor 2 (D2) signaling. Further, in the presence of the mutant protein, we show that 80% reduction of mutant JIP3>80% and 60% reduction of wild-type JIP3 by non-allele selective phosphorothioate (PS)-modified antisense oligonucleotides (ASOs) is well tolerated by several types of cells in vitro. Our study identifies several important new roles for JIP3 and provides important insights for therapeutic approaches, including antisense oligonucleotide reduction of JIP3.
Authors
Wei Zhang, Swapnil Mittal, Ria Thomas, Anahid Foroughishafiei, Ricardo Nunes Bastos, Wendy K. Chung, Konstantina Skourti-Stathaki, Stanley T. Crooke
Abstract
Inflammation is a critical pathological process in myocardial infarction. Although immunosuppressive therapies can mitigate inflammatory responses and improve outcomes in myocardial infarction, they also increase the risk of infections. Identifying novel regulators of local cardiac inflammation could provide safer therapeutic targets for myocardial ischemia/reperfusion injury. In this study, we identified a previously unknown micropeptide, which we named Inflammation Associated MicroPeptide (IAMP). IAMP is predominantly expressed in cardiac fibroblasts, and its expression is closely associated with cardiac inflammation. Down-regulation of IAMP promotes, whereas its overexpression prevents, the transformation of cardiac fibroblasts into a more inflammatory phenotype under stressed/stimulated conditions, as evidenced by changes in the expression and secretion of pro-inflammatory cytokines. Consequently, loss of IAMP function leads to uncontrolled inflammation and worsens cardiac injury following ischemia/reperfusion surgery. Mechanistically, IAMP promotes the degradation of HIF-1α by interacting with its stabilizing partner HSP90, and thus suppresses the transcription of pro-inflammatory genes downstream of HIF-1α. This study underscores the significance of fibroblast-mediated inflammation in cardiac ischemia/reperfusion injury and highlights the therapeutic potential of targeting micropeptides for myocardial infarction.
Authors
Youchen Yan, Tingting Zhang, Xin He, Tailai Du, Gang Dai, Xingfeng Xu, Zhuohui chen, Jialing Wu, Huimin Zhou, Yazhi Peng, Yan Li, Chen Liu, Xinxue Liao, Yugang Dong, Jing-song Ou, Zhan-Peng Huang
Abstract
Neurofilament accumulation is associated with many neurodegenerative diseases, but it is the primary pathology in giant axonal neuropathy (GAN). This childhood-onset autosomal recessive disease is caused by loss-of-function mutations in gigaxonin, the E3 adaptor protein that enables neurofilament degradation. Using a combination of genetic and RNA interference approaches, we found that dorsal root ganglia from mice lacking gigaxonin have impaired autophagy and lysosomal degradation through 2 mechanisms. First, neurofilament accumulations interfere with the distribution of autophagic organelles, impairing their maturation and fusion with lysosomes. Second, the accumulations attract the chaperone 14-3-3, which is responsible for the proper localization of the key autophagy regulator transcription factor EB (TFEB). We propose that this dual disruption of autophagy contributes to the pathogenesis of other neurodegenerative diseases involving neurofilament accumulations.
Authors
Jean-Michel Paumier, James Zewe, Chiranjit Panja, Melissa R. Pergande, Meghana Venkatesan, Eitan Israeli, Shikha Prasad, Natasha Snider, Jeffrey N. Savas, Puneet Opal
No posts were found with this tag.
