Volume 6 (2022)
Autophagic degradation of CNS myelin maintains axon integrity
Niki Ktena1, Stefanos Ioannis Kaplanis1, Irina Kolotuev2, Alexandros Georgilis1, Emmanouela Kallergi3, Vasiliki Stavroulaki1, Vassiliki Nikoletopoulou3, Maria Savvaki1, and Domna Karagogeos1
(Macro)autophagy is a major lysosome-dependent degradation mechanism which engulfs, removes and recycles unwanted cytoplasmic material, including damaged organelles and toxic protein aggregates. Although a few studies implicate autophagy in CNS demyelinating pathologies, its role, particularly in mature oligodendrocytes and CNS myelin, remains poorly studied. Here, using both pharmacological and genetic inhibition of the autophagic machinery, we provide evidence that autophagy is an essential mechanism for oligodendrocyte maturation in vitro. Our study reveals that two core myelin proteins, namely proteolipid protein (PLP) and myelin basic protein (MBP) are incorporated into autophagosomes in oligodendrocytes, resulting in their degradation. Furthermore, we ablated atg5, a core gene of the autophagic machinery, specifically in myelinating (...)
Unraveling the surface proteomic profile of multiple myeloma to reveal new immunotherapeutic targets and markers of drug resistance
Bonell Patiño-Escobar1, Ian D. Ferguson1,2, Arun P. Wiita1,3,4
The cell surface proteome (“surfaceome”) serves as the interface between diseased cells and their local microenvironment. In cancer, this compartment is critical not only for defining tumor biology but also serves as a rich source of potential therapeutic targets and diagnostic markers. Recently, we profiled the surfaceome of the blood cancer multiple myeloma, an incurable plasma cell malignancy. While available small molecule agents can drive initial remissions in myeloma, resistance inevitably occurs. Several new classes of immunotherapies targeting myeloma surface antigens, including antibody therapeutics and chimeric antigen receptor (CAR) T-cells, can further prolong survival. However, new approaches are still needed for those who relapse. We thus applied the glycoprotein cell surface capture (CSC) methodology to panel of multiple myeloma cell lines, identifying key surface protein features of malignant plasma cells. We characterized the most (...)
Pyroptosis in NLRP3 inflammasome-related atherosclerosis
Xiang Zeng1,#, Dongling Liu2,3,#, Xia Huo4, Yue Wu1, Cuiqing Liu1, Qinghua Sun1
Pyroptosis is a proinflammatory form of programmed cell death in response to inflammation. It involves in the pathogenesis and outcomes of atherosclerosis characterized by NLRP3 inflammasome assembly, membrane pore formation, cell swelling, pro-inflammatory mediator and cytokine release. There are known pyroptosis molecular pathways including the caspase-1 depended canonical signaling pathway and the caspase-4/5/11 determined non-canonical signaling pathway. It is essential to explore the connection among NLRP3 inflammasome, pyroptosis and atherosclerosis, which may shed light on the potential therapeutic strategies that target pyroptosis in atherosclerotic treatment.
COX-2 upregulation by tumour cells post-chemotherapy fuels the immune evasive dark side of cancer inflammation
Charlotte R. Bell1 and Santiago Zelenay1,2
Cytotoxic therapies, such as chemotherapy and radiotherapy, are mainstays of cancer treatment for both early and unresectable, advanced disease. In addition to debulking the tumour mass through direct killing of proliferating tumour cells, these treatments can promote tumour control via immune-stimulating effects. Nonetheless, chemoresistance and tumour relapse remain huge clinical problems, suggesting that induction of anti-cancer immunity post-cytotoxic therapy is often weak, not durable and/or overcome by immune evasive mechanisms. In our recent study (Nat Commun 13:2063), we demonstrate that cancer cell-intrinsic activation of the cyclooxygenase (COX)-2/prostaglandin E2 (PGE2) pathway post-chemotherapy treatment is a prevalent phenomenon which profoundly alters the inflammatory properties of the treated cancer cells. Of particular translational relevance, our findings support a model whereby upregulation of COX-2 expression (...)
Cardiac PI3K p110α attenuation delays aging and extends lifespan
Mahmoud Abdellatif1,2,3,4, Tobias Eisenberg4,5,6, Alexander Martin Heberle7, Kathrin Thedieck7,8,9, Guido Kroemer2,3,10 and Simon Sedej1,4,11
Phosphoinositide 3-kinase (PI3K) is a key component of the insulin signaling pathway that controls cellular me-tabolism and growth. Loss-of-function mutations in PI3K signaling and other downstream effectors of the insulin signaling pathway extend the lifespan of various model organisms. However, the pro-longevity effect appears to be sex-specific and young mice with reduced PI3K signaling have increased risk of cardiac disease. Hence, it remains elusive as to whether PI3K inhibition is a valid strategy to delay aging and extend healthspan in humans. We recently demonstrated that reduced PI3K activity in cardiomyocytes delays cardiac growth, causing subnormal contractility and cardiopulmonary functional capacity, as well as increased risk of mortality at young age. In stark contrast, in aged mice, experimental attenuation of PI3K signaling reduced the age-dependent decline in cardiac function and extended maximal lifespan, suggesting (...)
A purinergic call to arms from dying brown adipocytes
Mohammed K. Hankir1
Brown adipocytes react to temperature and nutritional challenges by ramping up their metabolism and generating heat. This adaptation to changes in the environment is crucial for defending organismal homeostasis, but is impaired in obesity and during aging. Writing in Nature, Niemann et al. show that brown adipocytes become apoptotic under thermoneutral conditions and release ATP, which in turn is converted extracellularly into inosine. They further present evidence that pharmacological and genetic manipulations that enhance signalling of this purine metabolite stimulates thermo-genesis in brown adipocytes and promotes metabolic health.
Could TNF-antagonists be a novel treatment strategy for BPH patients?
Renee E. Vickman1, Omar E. Franco1 and Simon W. Hayward1
Tumor necrosis factor (TNF) is widely recognized as a pivotal player in both systemic and local inflammatory processes. Due to the critical role this molecule has in driving both chronic and acute inflammation, it was among the earliest therapeutic targets utilized for pa-tients with autoimmune (AI) diseases. While inflamma-tion in the prostate is commonly observed, the organ has not previously been considered a target of systemic inflammation associated with some AI diseases. In pa-tients with benign prostatic hyperplasia (BPH), chronic inflammation is common, and immune cells represent a significant proportion of cells in the organ. Accumulation of inflammatory cells may be a response to an initial in-sult and/or a factor in driving BPH pathogenesis. Cer-tainly, inflammation can limit the efficacy of existing medical therapies in these patients. We previously showed that a pattern of gene expression in BPH tissues from patients who had progressed to indication-specific surgery was consistent with the changes seen in AI dis-eases. Recently, we demonstrated that patients with AI disease have an approximately 50% increase in (...)
A pathological role of the Hsp40 protein Ydj1/DnaJA1 in models of Alzheimer’s disease
Jelena Tadic1,2, Julia Ring1, Andrea Jerkovic1, Selena Ristic1, Marta Maglione3,4, Jörn Dengjel5, Stephan J. Sigrist3,4 and Tobias Eisenberg1,2,6
Alzheimer’s disease (AD) is the most common form of dementia with millions of people affected worldwide. Pathophysiological manifestations of AD include the extracellular accumulation of amyloid beta (Abeta) peptides, products of the proteolytic cleavage of the amyloid precursor protein APP. Increasing evidence suggests that Abeta peptides also accumulate intracellularly, triggering neurotoxic events such as mitochondrial dysfunction. However, the molecular factors driving formation and toxicity of intracellular Abeta are poorly understood. In our recent study [EMBO Mol Med 2022 – e13952], we used different eukaryotic model systems to identify such factors. Based on a genetic screen in yeast and subsequent molecular analyses, we found that both the yeast chaperone Ydj1 and its human ortholog DnaJA1 physically interact with Abeta, facilitate the aggregation of Abeta (...)
COX4-1 promotes mitochondrial supercomplex assembly and limits reactive oxide species production in radioresistant GBM
Claudia R. Oliva1, Md Yousuf Ali1,2, Susanne Flor1 and Corinne E. Griguer1
Glioblastoma (GBM) is a fatal disease with recurrences often associated with radioresistance. Although often effective at treating newly diagnosed GBM, increasing evidence suggests that radiotherapy-induced alterations in tumor metabolism promote GBM recurrence and aggressiveness. Using isogenic radiosensitive and radioresistant GBM cell lines and patient-derived xenolines, we found that acquired radioresistance is associated with a shift from a glycolytic metabolism to a more oxidative metabolism marked by a substantial increase in the activity of the mitochondrial respiratory chain complex cytochrome c oxidase (CcO). This elevated CcO activity was associated with a switch in the isoform expression of the CcO regulatory subunit COX4, from COX4-2 to COX4-1, assembly of CcO-containing mitochondrial supercomplexes (SCs), and reduced superoxide (O2●-) production. Overexpression of COX4-1 in the radiosensitive cells was sufficient to promote the switch from glycolytic to (...)
Autophagic degradation of CNS myelin maintains axon integrity
Niki Ktena1, Stefanos Ioannis Kaplanis1, Irina Kolotuev2, Alexandros Georgilis1, Emmanouela Kallergi3, Vasiliki Stavroulaki1, Vassiliki Nikoletopoulou3, Maria Savvaki1, and Domna Karagogeos1
(Macro)autophagy is a major lysosome-dependent degradation mechanism which engulfs, removes and recycles unwanted cytoplasmic material, including damaged organelles and toxic protein aggregates. Although a few studies implicate autophagy in CNS demyelinating pathologies, its role, particularly in mature oligodendrocytes and CNS myelin, remains poorly studied. Here, using both pharmacological and genetic inhibition of the autophagic machinery, we provide evidence that autophagy is an essential mechanism for oligodendrocyte maturation in vitro. Our study reveals that two core myelin proteins, namely proteolipid protein (PLP) and myelin basic protein (MBP) are incorporated into autophagosomes in oligodendrocytes, resulting in their degradation. Furthermore, we ablated atg5, a core gene of the autophagic machinery, specifically in myelinating (...)
Unraveling the surface proteomic profile of multiple myeloma to reveal new immunotherapeutic targets and markers of drug resistance
Bonell Patiño-Escobar1, Ian D. Ferguson1,2, Arun P. Wiita1,3,4
The cell surface proteome (“surfaceome”) serves as the interface between diseased cells and their local microenvironment. In cancer, this compartment is critical not only for defining tumor biology but also serves as a rich source of potential therapeutic targets and diagnostic markers. Recently, we profiled the surfaceome of the blood cancer multiple myeloma, an incurable plasma cell malignancy. While available small molecule agents can drive initial remissions in myeloma, resistance inevitably occurs. Several new classes of immunotherapies targeting myeloma surface antigens, including antibody therapeutics and chimeric antigen receptor (CAR) T-cells, can further prolong survival. However, new approaches are still needed for those who relapse. We thus applied the glycoprotein cell surface capture (CSC) methodology to panel of multiple myeloma cell lines, identifying key surface protein features of malignant plasma cells. We characterized the most (...)
Pyroptosis in NLRP3 inflammasome-related atherosclerosis
Xiang Zeng1,#, Dongling Liu2,3,#, Xia Huo4, Yue Wu1, Cuiqing Liu1, Qinghua Sun1
Pyroptosis is a proinflammatory form of programmed cell death in response to inflammation. It involves in the pathogenesis and outcomes of atherosclerosis characterized by NLRP3 inflammasome assembly, membrane pore formation, cell swelling, pro-inflammatory mediator and cytokine release. There are known pyroptosis molecular pathways including the caspase-1 depended canonical signaling pathway and the caspase-4/5/11 determined non-canonical signaling pathway. It is essential to explore the connection among NLRP3 inflammasome, pyroptosis and atherosclerosis, which may shed light on the potential therapeutic strategies that target pyroptosis in atherosclerotic treatment.
COX-2 upregulation by tumour cells post-chemotherapy fuels the immune evasive dark side of cancer inflammation
Charlotte R. Bell1 and Santiago Zelenay1,2
Cytotoxic therapies, such as chemotherapy and radiotherapy, are mainstays of cancer treatment for both early and unresectable, advanced disease. In addition to debulking the tumour mass through direct killing of proliferating tumour cells, these treatments can promote tumour control via immune-stimulating effects. Nonetheless, chemoresistance and tumour relapse remain huge clinical problems, suggesting that induction of anti-cancer immunity post-cytotoxic therapy is often weak, not durable and/or overcome by immune evasive mechanisms. In our recent study (Nat Commun 13:2063), we demonstrate that cancer cell-intrinsic activation of the cyclooxygenase (COX)-2/prostaglandin E2 (PGE2) pathway post-chemotherapy treatment is a prevalent phenomenon which profoundly alters the inflammatory properties of the treated cancer cells. Of particular translational relevance, our findings support a model whereby upregulation of COX-2 expression (...)
Cardiac PI3K p110α attenuation delays aging and extends lifespan
Mahmoud Abdellatif1,2,3,4, Tobias Eisenberg4,5,6, Alexander Martin Heberle7, Kathrin Thedieck7,8,9, Guido Kroemer2,3,10 and Simon Sedej1,4,11
Phosphoinositide 3-kinase (PI3K) is a key component of the insulin signaling pathway that controls cellular me-tabolism and growth. Loss-of-function mutations in PI3K signaling and other downstream effectors of the insulin signaling pathway extend the lifespan of various model organisms. However, the pro-longevity effect appears to be sex-specific and young mice with reduced PI3K signaling have increased risk of cardiac disease. Hence, it remains elusive as to whether PI3K inhibition is a valid strategy to delay aging and extend healthspan in humans. We recently demonstrated that reduced PI3K activity in cardiomyocytes delays cardiac growth, causing subnormal contractility and cardiopulmonary functional capacity, as well as increased risk of mortality at young age. In stark contrast, in aged mice, experimental attenuation of PI3K signaling reduced the age-dependent decline in cardiac function and extended maximal lifespan, suggesting (...)
A purinergic call to arms from dying brown adipocytes
Mohammed K. Hankir1
Brown adipocytes react to temperature and nutritional challenges by ramping up their metabolism and generating heat. This adaptation to changes in the environment is crucial for defending organismal homeostasis, but is impaired in obesity and during aging. Writing in Nature, Niemann et al. show that brown adipocytes become apoptotic under thermoneutral conditions and release ATP, which in turn is converted extracellularly into inosine. They further present evidence that pharmacological and genetic manipulations that enhance signalling of this purine metabolite stimulates thermo-genesis in brown adipocytes and promotes metabolic health.
Unraveling the surface proteomic profile of multiple myeloma to reveal new immunotherapeutic targets and markers of drug resistance
Bonell Patiño-Escobar1, Ian D. Ferguson1,2, Arun P. Wiita1,3,4
The cell surface proteome (“surfaceome”) serves as the interface between diseased cells and their local microenvironment. In cancer, this compartment is critical not only for defining tumor biology but also serves as a rich source of potential therapeutic targets and diagnostic markers. Recently, we profiled the surfaceome of the blood cancer multiple myeloma, an incurable plasma cell malignancy. While available small molecule agents can drive initial remissions in myeloma, resistance inevitably occurs. Several new classes of immunotherapies targeting myeloma surface antigens, including antibody therapeutics and chimeric antigen receptor (CAR) T-cells, can further prolong survival. However, new approaches are still needed for those who relapse. We thus applied the glycoprotein cell surface capture (CSC) methodology to panel of multiple myeloma cell lines, identifying key surface protein features of malignant plasma cells. We characterized the most (...)
Pyroptosis in NLRP3 inflammasome-related atherosclerosis
Xiang Zeng1,#, Dongling Liu2,3,#, Xia Huo4, Yue Wu1, Cuiqing Liu1, Qinghua Sun1
Pyroptosis is a proinflammatory form of programmed cell death in response to inflammation. It involves in the pathogenesis and outcomes of atherosclerosis characterized by NLRP3 inflammasome assembly, membrane pore formation, cell swelling, pro-inflammatory mediator and cytokine release. There are known pyroptosis molecular pathways including the caspase-1 depended canonical signaling pathway and the caspase-4/5/11 determined non-canonical signaling pathway. It is essential to explore the connection among NLRP3 inflammasome, pyroptosis and atherosclerosis, which may shed light on the potential therapeutic strategies that target pyroptosis in atherosclerotic treatment.
COX-2 upregulation by tumour cells post-chemotherapy fuels the immune evasive dark side of cancer inflammation
Charlotte R. Bell1 and Santiago Zelenay1,2
Cytotoxic therapies, such as chemotherapy and radiotherapy, are mainstays of cancer treatment for both early and unresectable, advanced disease. In addition to debulking the tumour mass through direct killing of proliferating tumour cells, these treatments can promote tumour control via immune-stimulating effects. Nonetheless, chemoresistance and tumour relapse remain huge clinical problems, suggesting that induction of anti-cancer immunity post-cytotoxic therapy is often weak, not durable and/or overcome by immune evasive mechanisms. In our recent study (Nat Commun 13:2063), we demonstrate that cancer cell-intrinsic activation of the cyclooxygenase (COX)-2/prostaglandin E2 (PGE2) pathway post-chemotherapy treatment is a prevalent phenomenon which profoundly alters the inflammatory properties of the treated cancer cells. Of particular translational relevance, our findings support a model whereby upregulation of COX-2 expression (...)
Could TNF-antagonists be a novel treatment strategy for BPH patients?
Renee E. Vickman1, Omar E. Franco1 and Simon W. Hayward1
Tumor necrosis factor (TNF) is widely recognized as a pivotal player in both systemic and local inflammatory processes. Due to the critical role this molecule has in driving both chronic and acute inflammation, it was among the earliest therapeutic targets utilized for pa-tients with autoimmune (AI) diseases. While inflamma-tion in the prostate is commonly observed, the organ has not previously been considered a target of systemic inflammation associated with some AI diseases. In pa-tients with benign prostatic hyperplasia (BPH), chronic inflammation is common, and immune cells represent a significant proportion of cells in the organ. Accumulation of inflammatory cells may be a response to an initial in-sult and/or a factor in driving BPH pathogenesis. Cer-tainly, inflammation can limit the efficacy of existing medical therapies in these patients. We previously showed that a pattern of gene expression in BPH tissues from patients who had progressed to indication-specific surgery was consistent with the changes seen in AI dis-eases. Recently, we demonstrated that patients with AI disease have an approximately 50% increase in (...)
A pathological role of the Hsp40 protein Ydj1/DnaJA1 in models of Alzheimer’s disease
Jelena Tadic1,2, Julia Ring1, Andrea Jerkovic1, Selena Ristic1, Marta Maglione3,4, Jörn Dengjel5, Stephan J. Sigrist3,4 and Tobias Eisenberg1,2,6
Alzheimer’s disease (AD) is the most common form of dementia with millions of people affected worldwide. Pathophysiological manifestations of AD include the extracellular accumulation of amyloid beta (Abeta) peptides, products of the proteolytic cleavage of the amyloid precursor protein APP. Increasing evidence suggests that Abeta peptides also accumulate intracellularly, triggering neurotoxic events such as mitochondrial dysfunction. However, the molecular factors driving formation and toxicity of intracellular Abeta are poorly understood. In our recent study [EMBO Mol Med 2022 – e13952], we used different eukaryotic model systems to identify such factors. Based on a genetic screen in yeast and subsequent molecular analyses, we found that both the yeast chaperone Ydj1 and its human ortholog DnaJA1 physically interact with Abeta, facilitate the aggregation of Abeta (...)
Genotoxic stress signalling as a driver of macrophage diversity
Ana Kasapi1,2 and Antigoni Triantafyllopoulou1,2
Tissue macrophages arise from yolk sac, fetal liver and hematopoietic progenitors and adopt diverse transcriptional programs and phenotypes, instructed by their microenvironment. In chronic inflammation, such as in chronic infections, autoimmunity, or cancer, tissue microenvironments change dramatically thus imprinting new programs on tissue macrophages. While stress is a known driver of carcinogenesis in epithelial cells, emerging evidence suggests that macrophage responses to genotoxic stress are embedded in their ‘physiologic’ immune and tissue healing programs and in most cases do not lead to myeloid malignancies. The role of genotoxic stress as an instructor of macrophage-mediated immune defense and tissue remodeling is only beginning to be understood. Here, we review the evidence showing that genotoxic stress, which macrophages and their precursors face (...)
Cardiac PI3K p110α attenuation delays aging and extends lifespan
Mahmoud Abdellatif1,2,3,4, Tobias Eisenberg4,5,6, Alexander Martin Heberle7, Kathrin Thedieck7,8,9, Guido Kroemer2,3,10 and Simon Sedej1,4,11
Phosphoinositide 3-kinase (PI3K) is a key component of the insulin signaling pathway that controls cellular me-tabolism and growth. Loss-of-function mutations in PI3K signaling and other downstream effectors of the insulin signaling pathway extend the lifespan of various model organisms. However, the pro-longevity effect appears to be sex-specific and young mice with reduced PI3K signaling have increased risk of cardiac disease. Hence, it remains elusive as to whether PI3K inhibition is a valid strategy to delay aging and extend healthspan in humans. We recently demonstrated that reduced PI3K activity in cardiomyocytes delays cardiac growth, causing subnormal contractility and cardiopulmonary functional capacity, as well as increased risk of mortality at young age. In stark contrast, in aged mice, experimental attenuation of PI3K signaling reduced the age-dependent decline in cardiac function and extended maximal lifespan, suggesting (...)
A purinergic call to arms from dying brown adipocytes
Mohammed K. Hankir1
Brown adipocytes react to temperature and nutritional challenges by ramping up their metabolism and generating heat. This adaptation to changes in the environment is crucial for defending organismal homeostasis, but is impaired in obesity and during aging. Writing in Nature, Niemann et al. show that brown adipocytes become apoptotic under thermoneutral conditions and release ATP, which in turn is converted extracellularly into inosine. They further present evidence that pharmacological and genetic manipulations that enhance signalling of this purine metabolite stimulates thermo-genesis in brown adipocytes and promotes metabolic health.