Antigen-mediated aggregation of immunoglobulin E (IgE) bound to the high-affinity IgE receptor (FcεRI) initiates mast cell activation and allergic inflammation. Here, we investigated the role of ubiquitin-specific protease 5 (USP5) in IgE-mediated mast cell activation and its regulation of FcεRIγ stability. We found that USP5 knockdown inhibited the IgE-induced release of β-hexosaminidase and histamine from mast cells and attenuated allergic inflammation in mice. USP5 interacted with FcεRIγ in mast cells, leading to its deubiquitylation and stabilization. In addition, USP5 reversed the K48-linked polyubiquitylation of FcεRIγ. USP5 knockdown in mast cells or HEK293T cells increased the binding of the E3 ubiquitin ligase Cbl-b to FcεRIγ, leading to an increase in FcεRIγ polyubiquitylation and degradation. The USP5 inhibitor WP1130 attenuated IgE-mediated mast cell activation and allergic inflammation in mice. Together, these findings describe the molecular mechanism of USP5-mediated regulation of FcεRIγ stability in mast cells and identify the USP5-FcεRIγ axis as a potential drug target for the therapy of IgE/FcεRI-mediated allergic diseases.
{"title":"USP5 deubiquitylates and stabilizes FcεRIγ to enhance IgE-induced mast cell activation and allergic inflammation","authors":"Zi-Wen Zhou, Xue-Ting Xu, Qiu-Ni Liang, Yan-Mei Zhou, Wan-Zhen Hu, Shan Liu, Yu-Xin Jiao, Shu-Chen Zhang, Kunmei Ji, Jia-Jie Chen","doi":"10.1126/scisignal.adr3411","DOIUrl":"10.1126/scisignal.adr3411","url":null,"abstract":"<div >Antigen-mediated aggregation of immunoglobulin E (IgE) bound to the high-affinity IgE receptor (FcεRI) initiates mast cell activation and allergic inflammation. Here, we investigated the role of ubiquitin-specific protease 5 (USP5) in IgE-mediated mast cell activation and its regulation of FcεRIγ stability. We found that USP5 knockdown inhibited the IgE-induced release of β-hexosaminidase and histamine from mast cells and attenuated allergic inflammation in mice. USP5 interacted with FcεRIγ in mast cells, leading to its deubiquitylation and stabilization. In addition, USP5 reversed the K48-linked polyubiquitylation of FcεRIγ. USP5 knockdown in mast cells or HEK293T cells increased the binding of the E3 ubiquitin ligase Cbl-b to FcεRIγ, leading to an increase in FcεRIγ polyubiquitylation and degradation. The USP5 inhibitor WP1130 attenuated IgE-mediated mast cell activation and allergic inflammation in mice. Together, these findings describe the molecular mechanism of USP5-mediated regulation of FcεRIγ stability in mast cells and identify the USP5-FcεRIγ axis as a potential drug target for the therapy of IgE/FcεRI-mediated allergic diseases.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 897","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144725733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-29DOI: 10.1126/scisignal.adt6552
Nicole Kabella, Florian P. Bayer, Konstantinos Stamatiou, Miriam Abele, Amirhossein Sakhteman, Yun-Chien Chang, Vinona Wagner, Antje Gabriel, Johannes Krumm, Maria Reinecke, Melanie Holzner, Michael Aigner, Matthew The, Hannes Hahne, Florian Bassermann, Christina Ludwig, Paola Vagnarelli, Bernhard Kuster
Mutations that activate the small GTPase KRAS are a frequent genetic alteration in cancer, and drug discovery efforts have led to inhibitors that block KRAS activity. We sought to better understand oncogenic KRAS signaling and the cytostatic effects of drugs that target this system. We performed proteomic analyses to investigate changes in protein abundance and posttranslational modifications in inhibitor-treated human KRAS-mutant pancreatic (KRAS G12C and G12D) and lung cancer (KRAS G12C) cells. The inhibitors used target these mutant forms of KRAS, the downstream effectors MEK and ERK, and the upstream regulators SHP2 and SOS1. Comparisons of phosphoproteomes between cell lines revealed a core KRAS signaling signature and cell line–specific signaling networks. In all cell lines, phosphoproteomes were dominated by different degrees of autonomous, oncogenic KRAS activity. Comparison of phosphoproteomes after short and long drug exposures revealed the temporal dynamics of KRAS-MEK-ERK axis inhibition that resulted in cell cycle exit. This transition to a quiescent state occurred in the absence of substantial proteome remodeling but included broad changes in protein phosphorylation and ubiquitylation. The collective data reveal insights into oncogenic KRAS signaling, place many additional proteins into this functional context, and implicate cell cycle exit as a mechanism by which cells evade death upon KRAS signaling inhibition.
{"title":"Proteomic analyses identify targets, pathways, and cellular consequences of oncogenic KRAS signaling","authors":"Nicole Kabella, Florian P. Bayer, Konstantinos Stamatiou, Miriam Abele, Amirhossein Sakhteman, Yun-Chien Chang, Vinona Wagner, Antje Gabriel, Johannes Krumm, Maria Reinecke, Melanie Holzner, Michael Aigner, Matthew The, Hannes Hahne, Florian Bassermann, Christina Ludwig, Paola Vagnarelli, Bernhard Kuster","doi":"10.1126/scisignal.adt6552","DOIUrl":"10.1126/scisignal.adt6552","url":null,"abstract":"<div >Mutations that activate the small GTPase KRAS are a frequent genetic alteration in cancer, and drug discovery efforts have led to inhibitors that block KRAS activity. We sought to better understand oncogenic KRAS signaling and the cytostatic effects of drugs that target this system. We performed proteomic analyses to investigate changes in protein abundance and posttranslational modifications in inhibitor-treated human KRAS-mutant pancreatic (KRAS G12C and G12D) and lung cancer (KRAS G12C) cells. The inhibitors used target these mutant forms of KRAS, the downstream effectors MEK and ERK, and the upstream regulators SHP2 and SOS1. Comparisons of phosphoproteomes between cell lines revealed a core KRAS signaling signature and cell line–specific signaling networks. In all cell lines, phosphoproteomes were dominated by different degrees of autonomous, oncogenic KRAS activity. Comparison of phosphoproteomes after short and long drug exposures revealed the temporal dynamics of KRAS-MEK-ERK axis inhibition that resulted in cell cycle exit. This transition to a quiescent state occurred in the absence of substantial proteome remodeling but included broad changes in protein phosphorylation and ubiquitylation. The collective data reveal insights into oncogenic KRAS signaling, place many additional proteins into this functional context, and implicate cell cycle exit as a mechanism by which cells evade death upon KRAS signaling inhibition.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 897","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144725732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-22DOI: 10.1126/scisignal.adp6006
Yan Sun, Abhishek Kumar Mishra, Vasanth Chanrasekhar, Michaela Door, Chase W. Kessinger, Bing Xu, Peiyang Tang, Yunan Gao, Sarah Kamli-Salino, Katherine Nelson, Mirela Delibegovic, E. Dale Abel, Jonanthan A. Kirk, Maria I. Kontaridis
Cardiomyocytes (CMs) normally use fatty acid oxidation (FAO) as their primary energy source. In response to pathological stress, the substrate preference of CMs switches from FAO to glucose metabolism, leading to the development of heart failure. Obesity increases this pathological risk of cardiovascular disease. We focused on protein tyrosine phosphatase 1B (PTP1B), an inhibitor of insulin signaling, the abundance and activity of which are increased in brain, muscle, and adipose tissues in obese and/or diabetic animals and in obese human patients. We generated mice with CM-specific deficiency in PTP1B (PTP1Bfl/fl::ꭤMHCCre/+) to investigate the CM-specific role of PTP1B in response to cardiac dysfunction induced by high-fat diet (HFD) feeding. Although no physiological or functional cardiac differences were observed at baseline, PTP1Bfl/fl::ꭤMHCCre/+ mice were protected against development of cardiac hypertrophy, mitochondrial dysfunction, and cardiac steatosis induced by HFD feeding. Metabolomics data revealed that hearts with CM-specific deletion of PTP1B had increased FAO and lipolysis but reduced glucose metabolism. Furthermore, phosphoproteomics analyses and mechanistic studies identified an axis involving the kinases PKM2 and AMPK downstream of PTP1B in the heart, which collectively acted to promote FAO and suppress lipogenesis. Together, these results suggest that CM-specific deletion of PTP1B prevents a substrate switch from FAO to glucose metabolism, protecting the heart against the development of HFD-induced cardiac hypertrophy and dysfunction.
{"title":"Deletion of PTP1B in cardiomyocytes alters cardiac metabolic signaling to protect against cardiomyopathy induced by a high-fat diet","authors":"Yan Sun, Abhishek Kumar Mishra, Vasanth Chanrasekhar, Michaela Door, Chase W. Kessinger, Bing Xu, Peiyang Tang, Yunan Gao, Sarah Kamli-Salino, Katherine Nelson, Mirela Delibegovic, E. Dale Abel, Jonanthan A. Kirk, Maria I. Kontaridis","doi":"10.1126/scisignal.adp6006","DOIUrl":"10.1126/scisignal.adp6006","url":null,"abstract":"<div >Cardiomyocytes (CMs) normally use fatty acid oxidation (FAO) as their primary energy source. In response to pathological stress, the substrate preference of CMs switches from FAO to glucose metabolism, leading to the development of heart failure. Obesity increases this pathological risk of cardiovascular disease. We focused on protein tyrosine phosphatase 1B (PTP1B), an inhibitor of insulin signaling, the abundance and activity of which are increased in brain, muscle, and adipose tissues in obese and/or diabetic animals and in obese human patients. We generated mice with CM-specific deficiency in PTP1B (<i>PTP1B<sup>fl/fl</sup>::ꭤMHC<sup>Cre/+</sup></i>) to investigate the CM-specific role of PTP1B in response to cardiac dysfunction induced by high-fat diet (HFD) feeding. Although no physiological or functional cardiac differences were observed at baseline, <i>PTP1B<sup>fl/fl</sup>::ꭤMHC<sup>Cre/+</sup></i> mice were protected against development of cardiac hypertrophy, mitochondrial dysfunction, and cardiac steatosis induced by HFD feeding. Metabolomics data revealed that hearts with CM-specific deletion of PTP1B had increased FAO and lipolysis but reduced glucose metabolism. Furthermore, phosphoproteomics analyses and mechanistic studies identified an axis involving the kinases PKM2 and AMPK downstream of PTP1B in the heart, which collectively acted to promote FAO and suppress lipogenesis. Together, these results suggest that CM-specific deletion of PTP1B prevents a substrate switch from FAO to glucose metabolism, protecting the heart against the development of HFD-induced cardiac hypertrophy and dysfunction.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 896","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.science.org/doi/reader/10.1126/scisignal.adp6006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144681637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-22DOI: 10.1126/scisignal.adr3738
Oleksandra Aust, Moritz R. T. Thiel, Eric Blanc, Mareen Lüthen, Viola Hollek, Rosario Astaburuaga-García, Bertram Klinger, Francisca Böhning, Alexandra Trinks, Dieter Beule, Björn Papke, David Horst, Nils Blüthgen, Christine Sers, Channing J. Der, Markus Morkel
Therapy-induced acquired resistance limits the clinical effectiveness of mutation-specific KRAS inhibitors in colorectal cancer (CRC). Here, we investigated whether broad-spectrum, active-state RAS inhibitors meet similar limitations. We found that KRAS-mutant CRC cell lines were sensitive to the RAS(ON) multiselective RAS inhibitor RMC-7977, given that treatment resulted in RAS-RAF-MEK-ERK pathway inhibition; halted proliferation; and, in some cases, induced apoptosis. RMC-7977 initially reduced the activity of a compartment-specific, dual-color reporter of ERK activity, with reporter reactivation emerging after long-term dose escalation. These drug-resistant cell populations exhibited distinct patterns of phospho-protein abundance, transcriptional activities, and genomic mutations, including a Y71H mutation in KRAS and an S257L mutation in RAF1. Transgenic expression of KRASG13D, Y71H or RAF1S257L in drug-sensitive CRC cells induced resistance to RMC-7977. CRC cells that were resistant to RMC-7977 and harboring RAF1S257L exhibited synergistic sensitivity to concurrent inhibition of RAS and RAF. Our findings demonstrate the power of reporter-assisted screening together with single-cell analyses for dissecting the complex landscape of therapy resistance. The strategy offers opportunities to develop clinically relevant combinatorial treatments to counteract the emergence of resistant cancer cells.
{"title":"Reporter-based screening identifies RAS-RAF mutations as drivers of resistance to active-state RAS inhibitors in colorectal cancer","authors":"Oleksandra Aust, Moritz R. T. Thiel, Eric Blanc, Mareen Lüthen, Viola Hollek, Rosario Astaburuaga-García, Bertram Klinger, Francisca Böhning, Alexandra Trinks, Dieter Beule, Björn Papke, David Horst, Nils Blüthgen, Christine Sers, Channing J. Der, Markus Morkel","doi":"10.1126/scisignal.adr3738","DOIUrl":"10.1126/scisignal.adr3738","url":null,"abstract":"<div >Therapy-induced acquired resistance limits the clinical effectiveness of mutation-specific KRAS inhibitors in colorectal cancer (CRC). Here, we investigated whether broad-spectrum, active-state RAS inhibitors meet similar limitations. We found that KRAS-mutant CRC cell lines were sensitive to the RAS(ON) multiselective RAS inhibitor RMC-7977, given that treatment resulted in RAS-RAF-MEK-ERK pathway inhibition; halted proliferation; and, in some cases, induced apoptosis. RMC-7977 initially reduced the activity of a compartment-specific, dual-color reporter of ERK activity, with reporter reactivation emerging after long-term dose escalation. These drug-resistant cell populations exhibited distinct patterns of phospho-protein abundance, transcriptional activities, and genomic mutations, including a Y71H mutation in KRAS and an S257L mutation in RAF1. Transgenic expression of KRAS<sup>G13D, Y71H</sup> or RAF1<sup>S257L</sup> in drug-sensitive CRC cells induced resistance to RMC-7977. CRC cells that were resistant to RMC-7977 and harboring RAF1<sup>S257L</sup> exhibited synergistic sensitivity to concurrent inhibition of RAS and RAF. Our findings demonstrate the power of reporter-assisted screening together with single-cell analyses for dissecting the complex landscape of therapy resistance. The strategy offers opportunities to develop clinically relevant combinatorial treatments to counteract the emergence of resistant cancer cells.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 896","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144681636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Serena Muratcioglu, Christopher A. Eide, Chien-Lun Hung, Kent Gorday, Emily Sumpena, Wenqi Zuo, Jay T. Groves, Brian J. Druker, John Kuriyan
Chromosomal translocations that fuse ABL1 to BCR or TEL cause human leukemias. In BCR-ABL and TEL-ABL fusion proteins, oligomerization and loss of an autoinhibitory myristoylation site in the SH3 domain of ABL lead to increased ABL tyrosine kinase activity. We assessed the ability of asciminib, an allosteric inhibitor of BCR-ABL that binds to the myristoyl-binding site in the ABL kinase domain, to inhibit these fusion proteins. Although the ABL components of the two fusion proteins have identical sequences, asciminib was much less effective against TEL-ABL than it was against BCR-ABL in cell-growth assays. In contrast, ATP-competitive tyrosine kinase inhibitors, such as imatinib and ponatinib, were equally effective against both fusion proteins. A helix in the ABL kinase domain that closes over bound asciminib was required for the sensitivity of BCR-ABL to the drug but had no effect on that of TEL-ABL, suggesting that the native autoinhibitory mechanism that asciminib engages in BCR-ABL is disrupted in TEL-ABL. Single-molecule microscopy demonstrated that BCR-ABL was mainly dimeric in cells, whereas TEL-ABL formed higher-order oligomers, which promoted trans-autophosphorylation, including of a regulatory phosphorylation site (Tyr89) in the SH3 domain of ABL. Nonphosphorylated TEL-ABL was intrinsically susceptible to inhibition by asciminib, but phosphorylation at Tyr89 disassembled the autoinhibited conformation of ABL, thereby preventing asciminib from binding. Our results demonstrate that phosphorylation determines whether an ABL fusion protein is sensitive to allosteric inhibition.
{"title":"Autophosphorylation of oncoprotein TEL-ABL in myeloid and lymphoid cells confers resistance to the allosteric ABL inhibitor asciminib","authors":"Serena Muratcioglu, Christopher A. Eide, Chien-Lun Hung, Kent Gorday, Emily Sumpena, Wenqi Zuo, Jay T. Groves, Brian J. Druker, John Kuriyan","doi":"","DOIUrl":"","url":null,"abstract":"<div >Chromosomal translocations that fuse <i>ABL1</i> to <i>BCR</i> or <i>TEL</i> cause human leukemias. In BCR-ABL and TEL-ABL fusion proteins, oligomerization and loss of an autoinhibitory myristoylation site in the SH3 domain of ABL lead to increased ABL tyrosine kinase activity. We assessed the ability of asciminib, an allosteric inhibitor of BCR-ABL that binds to the myristoyl-binding site in the ABL kinase domain, to inhibit these fusion proteins. Although the ABL components of the two fusion proteins have identical sequences, asciminib was much less effective against TEL-ABL than it was against BCR-ABL in cell-growth assays. In contrast, ATP-competitive tyrosine kinase inhibitors, such as imatinib and ponatinib, were equally effective against both fusion proteins. A helix in the ABL kinase domain that closes over bound asciminib was required for the sensitivity of BCR-ABL to the drug but had no effect on that of TEL-ABL, suggesting that the native autoinhibitory mechanism that asciminib engages in BCR-ABL is disrupted in TEL-ABL. Single-molecule microscopy demonstrated that BCR-ABL was mainly dimeric in cells, whereas TEL-ABL formed higher-order oligomers, which promoted trans-autophosphorylation, including of a regulatory phosphorylation site (Tyr<sup>89</sup>) in the SH3 domain of ABL. Nonphosphorylated TEL-ABL was intrinsically susceptible to inhibition by asciminib, but phosphorylation at Tyr<sup>89</sup> disassembled the autoinhibited conformation of ABL, thereby preventing asciminib from binding. Our results demonstrate that phosphorylation determines whether an ABL fusion protein is sensitive to allosteric inhibition.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 895","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marissa Lindman, Irving Estevez, Eduard Marmut, Evan M. DaPrano, Tsui-Wen Chou, Kimberly Newman, Colm Atkins, Natasha M. O’Brown, Brian P. Daniels
Flaviviruses pose a substantial threat to public health because of their ability to infect the central nervous system (CNS). Receptor-interacting protein kinase 3 (RIPK3) is a central coordinator that promotes neuroinflammation during viral infection of the CNS, a role that occurs independently of its canonical function in inducing necroptosis. Here, we used mouse genetic tools to induce astrocyte-specific deletion, overexpression, and chemogenetic activation of RIPK3 to demonstrate an anti-inflammatory function for astrocytic RIPK3. RIPK3 activation in astrocytes promoted host survival during flavivirus encephalitis by limiting immune cell recruitment to the CNS. Despite inducing a proinflammatory transcriptional program, astrocytic RIPK3 restrained neuroinflammation by increasing the abundance of the protease inhibitor SerpinA3N, which preserved blood-brain barrier integrity, reduced leukocyte infiltration, and improved survival outcomes during flavivirus encephalitis. These findings highlight a previously unappreciated role for astrocytic RIPK3 in suppressing pathologic neuroinflammation.
黄病毒具有感染中枢神经系统（CNS）的能力，对公众健康构成重大威胁。受体相互作用蛋白激酶3 （Receptor-interacting protein kinase 3, RIPK3）是中枢协调物，在中枢神经系统病毒感染期间促进神经炎症，其作用独立于其诱导坏死性坏死的规范功能。在这里，我们使用小鼠遗传工具诱导星形胶质细胞特异性的RIPK3缺失、过表达和化学发生激活，以证明星形胶质细胞RIPK3的抗炎功能。星形胶质细胞中的RIPK3激活通过限制免疫细胞向中枢神经系统的募集来促进黄病毒脑炎期间宿主的存活。尽管诱导了促炎转录程序，星形细胞RIPK3通过增加蛋白酶抑制剂SerpinA3N的丰度来抑制神经炎症，从而保持了血脑屏障的完整性，减少了白细胞浸润，提高了黄病毒脑炎期间的生存结果。这些发现突出了星形细胞RIPK3在抑制病理性神经炎症中的作用。
{"title":"Astrocytic RIPK3 exerts protective anti-inflammatory activity in mice with viral encephalitis by transcriptional induction of serpins","authors":"Marissa Lindman, Irving Estevez, Eduard Marmut, Evan M. DaPrano, Tsui-Wen Chou, Kimberly Newman, Colm Atkins, Natasha M. O’Brown, Brian P. Daniels","doi":"","DOIUrl":"","url":null,"abstract":"<div >Flaviviruses pose a substantial threat to public health because of their ability to infect the central nervous system (CNS). Receptor-interacting protein kinase 3 (RIPK3) is a central coordinator that promotes neuroinflammation during viral infection of the CNS, a role that occurs independently of its canonical function in inducing necroptosis. Here, we used mouse genetic tools to induce astrocyte-specific deletion, overexpression, and chemogenetic activation of RIPK3 to demonstrate an anti-inflammatory function for astrocytic RIPK3. RIPK3 activation in astrocytes promoted host survival during flavivirus encephalitis by limiting immune cell recruitment to the CNS. Despite inducing a proinflammatory transcriptional program, astrocytic RIPK3 restrained neuroinflammation by increasing the abundance of the protease inhibitor SerpinA3N, which preserved blood-brain barrier integrity, reduced leukocyte infiltration, and improved survival outcomes during flavivirus encephalitis. These findings highlight a previously unappreciated role for astrocytic RIPK3 in suppressing pathologic neuroinflammation.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 895","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-08DOI: 10.1126/scisignal.adw4165
Kun Wang, Sophie E. Lockwood, Brendan D. Manning
The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) integrates signals from factors that both stimulate (exogenous growth factors) and are essential for (intracellular nutrients and energy) cellular growth. Activation of the protein kinase mTOR within mTORC1 results in the phosphorylation of downstream substrates that collectively stimulate biomass accumulation to drive cell growth. Many upstream signals, especially growth factors, regulate mTORC1 by inducing the phosphorylation of the tuberous sclerosis complex 2 (TSC2) subunit of the TSC protein complex, a conserved brake on mTORC1 activation and its promotion of cell growth. Cryo–electron microscopy studies of the TSC protein complex have revealed that this phosphoregulation of TSC2 occurs almost exclusively on residues in loops that are outside of the evolutionarily conserved core structural elements and that did not resolve in these structures. These phosphorylation-rich unstructured loops evolved with metazoans, suggesting that the regulation of mTORC1 by diverse growth factors likely evolved with the emergence of complex body plans and diverse cell types to coordinate cell growth and metabolism within and across distinct tissues. Unlike the core structure of TSC2, these loops lack disease-associated missense mutations. These features suggest that the regulatory loops on TSC2 are more amenable to evolutionary changes that enable diverse signals to converge on the TSC protein complex to regulate mTORC1.
{"title":"Evolution of growth factor signaling to the TSC complex to regulate mTORC1","authors":"Kun Wang, Sophie E. Lockwood, Brendan D. Manning","doi":"10.1126/scisignal.adw4165","DOIUrl":"10.1126/scisignal.adw4165","url":null,"abstract":"<div >The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) integrates signals from factors that both stimulate (exogenous growth factors) and are essential for (intracellular nutrients and energy) cellular growth. Activation of the protein kinase mTOR within mTORC1 results in the phosphorylation of downstream substrates that collectively stimulate biomass accumulation to drive cell growth. Many upstream signals, especially growth factors, regulate mTORC1 by inducing the phosphorylation of the tuberous sclerosis complex 2 (TSC2) subunit of the TSC protein complex, a conserved brake on mTORC1 activation and its promotion of cell growth. Cryo–electron microscopy studies of the TSC protein complex have revealed that this phosphoregulation of TSC2 occurs almost exclusively on residues in loops that are outside of the evolutionarily conserved core structural elements and that did not resolve in these structures. These phosphorylation-rich unstructured loops evolved with metazoans, suggesting that the regulation of mTORC1 by diverse growth factors likely evolved with the emergence of complex body plans and diverse cell types to coordinate cell growth and metabolism within and across distinct tissues. Unlike the core structure of TSC2, these loops lack disease-associated missense mutations. These features suggest that the regulatory loops on TSC2 are more amenable to evolutionary changes that enable diverse signals to converge on the TSC protein complex to regulate mTORC1.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"18 894","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144589981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-08DOI: 10.1126/scisignal.adt0983
Jacklyn Levey, Md. Abedin, Chi Zhang, Emmanuel Odame, Lingling Zhang, Ha-Neul Jo, Kaia Douglas, Heidi Roehrich, Zhe Chen, Harald J. Junge
Norrin-induced activation of β-catenin–dependent signaling through the receptor frizzled4 in endothelial cells (ECs) is essential for establishing and maintaining blood-CNS barrier function. We sought to determine how this pathway is modulated under stress or disease conditions. Specifically, we investigated the role of p53 in endothelial blood-CNS barriers because increased abundance of the transcription factor p53 in ECs correlates with leaky CNS blood vessels in type 2 diabetes. Using transcriptomic, cell-based, and mouse genetic approaches, we identified interplay between p53 and its negative regulator MDM2 and norrin/frizzled4 signaling. Mice with an EC-specific ablation of Mdm2 showed decreased norrin/frizzled4 signaling, reduced EC proliferation and retinal angiogenesis, and disrupted blood-retina barrier function, all of which were largely restored by concurrent Trp53 deletion. Decreased norrin/frizzled4 signaling and inhibition of EC proliferation in response to p53 were associated with reduced expression of the condensin I complex component non-SMC condensin I complex subunit H (NCAPH). This study identifies a regulator of norrin/frizzled4 signaling and suggests that the clinical use of MDM2 inhibitors might impair the blood-CNS barrier. In addition, NCAPH may be a downstream effector of p53 in ECs and a candidate gene for familial exudative vitreoretinopathy (FEVR), which is caused by defects in norrin signaling.
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