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Kadyan P, Singh L. Unraveling the mechanistic interplay of mediators orchestrating the neuroprotective potential of harmine. Pharmacol Rep 2024; 76:665-678. [PMID: 38758470 DOI: 10.1007/s43440-024-00602-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/27/2024] [Accepted: 05/07/2024] [Indexed: 05/18/2024]
Abstract
Neurodegenerative diseases (NDDs) encompass a range of conditions characterized by the specific dysfunction and continual decline of neurons, glial cells, and neural networks within the brain and spinal cord. The majority of NDDs exhibit similar underlying causes, including oxidative stress, neuroinflammation, and malfunctioning of mitochondria. Elevated levels of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), alongside decreased expression of brain-derived neurotrophic factor (BDNF) and glutamate transporter subtype 1 (GLT-1), constitute significant factors contributing to the pathogenesis of NDDs. Additionally, the dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A) gene has emerged as a significant target for the treatment of NDDs at the preclinical level. It significantly contributes to developmental brain defects, early onset neurodegeneration, neuronal loss, and dementia in Down syndrome. Moreover, an impaired ubiquitin-proteosome system (UPS) also plays a pathological role in NDDs. Malfunctioning of UPS leads to abnormal protein buildup or aggregation of α-synuclein. α-Synuclein is a highly soluble unfolded protein that accumulates in Lewy bodies and Lewy neurites in Parkinson's disease and other synucleinopathies. Recent research highlights the promising potential of natural products in combating NDDs relative to conventional therapies. Alkaloids have emerged as promising candidates in the fight against NDDs. Harmine is a tricyclic β-carboline alkaloid (harmala alkaloid) with one indole nucleus and a six-membered pyrrole ring. It is extracted from Banisteria caapi and Peganum harmala L. and exhibits diverse pharmacological properties, encompassing neuroprotective, antioxidant, anti-inflammatory, antidepressant, etc. Harmine has been reported to mediate its neuroprotective via reducing the level of inflammatory mediators, NADPH oxidase, AChE, BChE and reactive oxygen species (ROS). Whereas, it has been observed to increase the levels of BDNF, GLT-1 and anti-oxidant enzymes, along with protein kinase-A (PKA)-mediated UPS activation. This review aims to discuss the mechanistic interplay of various mediators involved in the neuroprotective effect of harmine.
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Affiliation(s)
- Pankaj Kadyan
- University Institute of Pharma Sciences, Chandigarh University, Mohali, Punjab, India
| | - Lovedeep Singh
- University Institute of Pharma Sciences, Chandigarh University, Mohali, Punjab, India.
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Chuah JJ, Daugherty MR, Smith DM. Occupancy of the HbYX hydrophobic pocket is sufficient to induce gate opening in the archaeal 20S proteasomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.21.595185. [PMID: 38826226 PMCID: PMC11142061 DOI: 10.1101/2024.05.21.595185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Enhancing proteasome function has been a long-standing but challenging target of interest for the potential treatment of neurodegenerative diseases, emphasizing the importance of understanding proteasome activation mechanisms. Most proteasome activator complexes use the C-terminal HbYX motif to bind and trigger gate-opening in the 20S proteasome. This study defines a critical molecular interaction in the HbYX mechanism that triggers gate opening. Here, we focus on the Hb site interaction and find it plays a surprisingly central and crucial role in driving the allosteric conformational changes that induce gate opening in the archaeal 20S. We examined the cryo-EM structure of two mutant archaeal proteasomes, αV24Y T20S and αV24F T20S. These two mutants were engineered to place a bulky aromatic residue in the HbYX hydrophobic pocket and both mutants are highly active, though their mechanisms of activation are undefined. Collectively, our findings indicate that the interaction between the Hb group of the HbYX motif and its corresponding hydrophobic pocket is sufficient to induce gate opening in a mechanistically similar way to the HbYX motif. The involved activation mechanism appears to involve expansion of this hydrophobic binding site affecting the state of the IT switch to triggering gate-opening. Furthermore, we show that the canonical αK66 residue, understood to be critical for proteasome activator binding, plays a key role in stabilizing the open gate, irrespective of activator binding. This study differentiates between the residues in the HbYX motif that support binding interactions ("YX") versus those that allosterically contribute to gate opening (Hb). The insights reported here will guide future drug development efforts, particularly in designing small molecule proteasome activators, by targeting the identified hydrophobic pocket.
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Affiliation(s)
- Janelle J.Y. Chuah
- Department of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 64 Medical Center Dr., Morgantown, WV USA
| | - Madalena R. Daugherty
- Department of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 64 Medical Center Dr., Morgantown, WV USA
| | - David M. Smith
- Department of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 64 Medical Center Dr., Morgantown, WV USA
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV USA
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Zhao T, Liu C, Liu L, Wang X, Liu C. Aging-accelerated differential production and aggregation of STAT3 protein in neuronal cells and neural stem cells in the male mouse spinal cord. Biogerontology 2023; 24:137-148. [PMID: 36550376 DOI: 10.1007/s10522-022-10004-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022]
Abstract
Aging-affected cellular compositions of the spinal cord are diverse and region specific. Age leads to the accumulation of abnormal protein aggregates and dysregulation of proteostasis. Dysregulated proteostasis and protein aggregates result from dysfunction of the ubiquitin-proteasome system (UPS) and autophagy. Understanding the molecular mechanisms of spinal cord aging is essential and important for scientists to discover new therapies for rejuvenation. We found age-related increases in STAT3 and decreases in Tuj1 in aging mouse spinal cords, which was characterized by increased expression of P16. Coaggregation of lysine-48 and lysine-63 ubiquitin with STAT3 was revealed in aging mouse spinal cords. STAT3-ubiquitin aggregates formed via lysine-48 and lysine-63 linkages were increased significantly in the aging spinal cords but not in central canal ependymal cells or neural stem cells in the spinal cord. These results highlight the increase in STAT3 and its region-specific aggregation and ubiquitin-conjugation during spinal cord aging.
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Affiliation(s)
- Tianyi Zhao
- Department of Histology and Embryology, School of Basic Medical Sciences, Institute of Stem Cell and Tissue Engineering, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Chang Liu
- Department of Orthopedics and Spine Surgery, The First Affiliated Hospital, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Lihua Liu
- Institute of Clinical Pharmacology, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Xinmeng Wang
- Department of Histology and Embryology, School of Basic Medical Sciences, Institute of Stem Cell and Tissue Engineering, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Chao Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Institute of Stem Cell and Tissue Engineering, Anhui Medical University, 81 Meishan Road, Hefei, 230032, Anhui, China.
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PKR Protects the Major Catalytic Subunit of PKA Cpk1 from FgBlm10-Mediated Proteasome Degradation in Fusarium graminearum. Int J Mol Sci 2022; 23:ijms231810208. [PMID: 36142119 PMCID: PMC9499325 DOI: 10.3390/ijms231810208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/17/2022] Open
Abstract
For optimal proteolytic function, the proteasome core (CP or 20S) must associate with activators. The cAMP-PKA pathway is reported to affect the activity of the proteasome in humans. However, the relationship between the proteasome and PKA is not well characterized. Our results showed that the major catalytic subunit Cpk1 was degraded without the protection of Pkr. Eleven (out of 67) pkr suppressors had FgBlm10 C-terminal truncation, one suppressor had an amino acid change mutation in the PRE6 ortholog (FGRRES_07282), and one in the PRE5 ortholog (FGRRES_05222). These mutations rescued the defects in growth and conidial morphology, Cpk1 stability, and PKA activities in the pkr mutant. The interaction of FgBlm10 with FgPre5 and FgPre6 were detected by co-immunoprecipitation, and the essential elements for their interaction were characterized, including the FgBlm10 C-terminus, amino acid D82 of FgPre6 and K62 of FgPre5. Additional FgBlm10-interacting proteins were identified in the wild type and pkr mutant, suggesting that PKA regulates the preference of FgBlm10-mediated proteasome assembly. In addition, PKA indirectly affected the phosphorylation of FgBlm10, and its localization in the nucleus. The truncation of the FgBlm10 C terminus also enhanced nuclear import and bleomycin resistance, suggesting its role in proteasome assembly at DNA damage sites. Collectively, our data demonstrated that regulation between PKA and proteasome degradation is critical for the vegetative growth of F. graminearum.
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Anderson RT, Bradley TA, Smith DM. Hyperactivation of the proteasome in Caenorhabditis elegans protects against proteotoxic stress and extends lifespan. J Biol Chem 2022; 298:102415. [PMID: 36007615 PMCID: PMC9486566 DOI: 10.1016/j.jbc.2022.102415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Virtually all age-related neurodegenerative diseases (NDs) can be characterized by the accumulation of proteins inside and outside the cell that are thought to significantly contribute to disease pathogenesis. One of the cell’s primary systems for the degradation of misfolded/damaged proteins is the ubiquitin proteasome system (UPS), and its impairment is implicated in essentially all NDs. Thus, upregulating this system to combat NDs has garnered a great deal of interest in recent years. Various animal models have focused on stimulating 26S activity and increasing 20S proteasome levels, but thus far, none have targeted intrinsic activation of the 20S proteasome itself. Therefore, we constructed an animal model that endogenously expresses a hyperactive, open gate proteasome in Caenorhabditis elegans. The gate-destabilizing mutation that we introduced into the nematode germline yielded a viable nematode population with enhanced proteasomal activity, including peptide, unstructured protein, and ubiquitin-dependent degradation activities. We determined these nematodes showed a significantly increased lifespan and substantial resistance to oxidative and proteotoxic stress but a significant decrease in fecundity. Our results show that introducing a constitutively active proteasome into a multicellular organism is feasible and suggests targeting the proteasome gating mechanism as a valid approach for future age-related disease research efforts in mammals.
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Affiliation(s)
- Raymond T Anderson
- Department of Biochemistry, West Virginia University School of Medicine, 64 Medical Center Dr., Morgantown, WV 26506
| | - Thomas A Bradley
- Department of Biochemistry, West Virginia University School of Medicine, 64 Medical Center Dr., Morgantown, WV 26506
| | - David M Smith
- Department of Biochemistry, West Virginia University School of Medicine, 64 Medical Center Dr., Morgantown, WV 26506.
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Beamish SB, Frick KM. A Putative Role for Ubiquitin-Proteasome Signaling in Estrogenic Memory Regulation. Front Behav Neurosci 2022; 15:807215. [PMID: 35145382 PMCID: PMC8821141 DOI: 10.3389/fnbeh.2021.807215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/20/2021] [Indexed: 12/31/2022] Open
Abstract
Sex steroid hormones such as 17β-estradiol (E2) are critical neuromodulators of hippocampal synaptic plasticity and hippocampus-dependent memory in both males and females. However, the mechanisms through which E2 regulates memory formation in both sexes remain unclear. Research to date suggests that E2 regulates hippocampus-dependent memory by activating numerous cell-signaling cascades to promote the synthesis of proteins that support structural changes at hippocampal synapses. However, this work has largely overlooked the equally important contributions of protein degradation mediated by the ubiquitin proteasome system (UPS) in remodeling the synapse. Despite being critically implicated in synaptic plasticity and successful formation of long-term memories, it remains unclear whether protein degradation mediated by the UPS is necessary for E2 to exert its beneficial effects on hippocampal plasticity and memory formation. The present article provides an overview of the receptor and signaling mechanisms so far identified as critical for regulating hippocampal E2 and UPS function in males and females, with a particular emphasis on the ways in which these mechanisms overlap to support structural integrity and protein composition of hippocampal synapses. We argue that the high degree of correspondence between E2 and UPS activity warrants additional study to examine the contributions of ubiquitin-mediated protein degradation in regulating the effects of sex steroid hormones on cognition.
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Mechanisms That Activate 26S Proteasomes and Enhance Protein Degradation. Biomolecules 2021; 11:biom11060779. [PMID: 34067263 PMCID: PMC8224753 DOI: 10.3390/biom11060779] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 02/07/2023] Open
Abstract
Although ubiquitination is widely assumed to be the only regulated step in the ubiquitin–proteasome pathway, recent studies have demonstrated several important mechanisms that regulate the activities of the 26S proteasome. Most proteasomes in cells are inactive but, upon binding a ubiquitinated substrate, become activated by a two-step mechanism requiring an association of the ubiquitin chain with Usp14 and then a loosely folded protein domain with the ATPases. The initial activation step is signaled by Usp14’s UBL domain, and many UBL-domain-containing proteins (e.g., Rad23, Parkin) also activate the proteasome. ZFAND5 is a distinct type of activator that binds ubiquitin conjugates and the proteasome and stimulates proteolysis during muscle atrophy. The proteasome’s activities are also regulated through subunit phosphorylation. Agents that raise cAMP and activate PKA stimulate within minutes Rpn6 phosphorylation and enhance the selective degradation of short-lived proteins. Likewise, hormones, fasting, and exercise, which raise cAMP, activate proteasomes and proteolysis in target tissues. Agents that raise cGMP and activate PKG also stimulate 26S activities but modify different subunit(s) and stimulate also the degradation of long-lived cell proteins. Both kinases enhance the selective degradation of aggregation-prone proteins that cause neurodegenerative diseases. These new mechanisms regulating proteolysis thus have clear physiological importance and therapeutic potential.
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Expanding the role of proteasome homeostasis in Parkinson's disease: beyond protein breakdown. Cell Death Dis 2021; 12:154. [PMID: 33542205 PMCID: PMC7862491 DOI: 10.1038/s41419-021-03441-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 02/06/2023]
Abstract
Proteasome is the principal hydrolytic machinery responsible for the great majority of protein degradation. The past three decades have testified prominent advances about proteasome involved in almost every aspect of biological processes. Nonetheless, inappropriate increase or decrease in proteasome function is regarded as a causative factor in several diseases. Proteasome abundance and proper assembly need to be precisely controlled. Indeed, various neurodegenerative diseases including Parkinson's disease (PD) share a common pathological feature, intracellular protein accumulation such as α-synuclein. Proteasome activation may effectively remove aggregates and prevent the neurodegeneration in PD, which provides a potential application for disease-modifying treatment. In this review, we build on the valuable discoveries related to different types of proteolysis by distinct forms of proteasome, and how its regulatory and catalytic particles promote protein elimination. Additionally, we summarize the emerging ideas on the proteasome homeostasis regulation by targeting transcriptional, translational, and post-translational levels. Given the imbalanced proteostasis in PD, the strategies for intensifying proteasomal degradation are advocated as a promising approach for PD clinical intervention.
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Phang MWL, Lew SY, Chung I, Lim WKS, Lim LW, Wong KH. Therapeutic roles of natural remedies in combating hereditary ataxia: A systematic review. Chin Med 2021; 16:15. [PMID: 33509239 PMCID: PMC7841890 DOI: 10.1186/s13020-020-00414-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 11/17/2020] [Accepted: 12/11/2020] [Indexed: 12/30/2022] Open
Abstract
Background Hereditary ataxia (HA) represents a group of genetically heterogeneous neurodegenerative diseases caused by dysfunction of the cerebellum or disruption of the connection between the cerebellum and other areas of the central nervous system. Phenotypic manifestation of HA includes unsteadiness of stance and gait, dysarthria, nystagmus, dysmetria and complaints of clumsiness. There are no specific treatments for HA. Management strategies provide supportive treatment to reduce symptoms. Objectives This systematic review aimed to identify, evaluate and summarise the published literature on the therapeutic roles of natural remedies in the treatment of HA to provide evidence for clinical practice. Methods A systematic literature search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Web of Science, PubMed and Science Direct Scopus were thoroughly searched for relevant published articles from June 2007 to July 2020. Results Ten pre-clinical and two clinical studies were eligible for inclusion in this systematic review. We identified the therapeutic roles of medicinal plants Brassica napus, Gardenia jasminoides, Gastrodia elata, Ginkgo biloba, Glycyrrhiza inflata, Paeonia lactiflora, Pueraria lobata and Rehmannia glutinosa; herbal formulations Shaoyao Gancao Tang and Zhengan Xifeng Tang; and medicinal mushroom Hericium erinaceus in the treatment of HA. In this review, we evaluated the mode of actions contributing to their therapeutic effects, including activation of the ubiquitin–proteasome system, activation of antioxidant pathways, maintenance of intracellular calcium homeostasis and regulation of chaperones. We also briefly highlighted the integral cellular signalling pathways responsible for orchestrating the mode of actions. Conclusion We reviewed the therapeutic roles of natural remedies in improving or halting the progression of HA, which warrant further study for applications into clinical practice.
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Affiliation(s)
- Michael Weng Lok Phang
- Department of Anatomy, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Sze Yuen Lew
- Department of Anatomy, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Ivy Chung
- Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - William Kiong-Seng Lim
- Faculty of Medicine and Health Sciences, Universiti Malaysia Sarawak, Kuching, Sarawak, 94300, Malaysia
| | - Lee Wei Lim
- Neuromodulation Laboratory, School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, China.
| | - Kah Hui Wong
- Department of Anatomy, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia.
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Paradiso A, Domingo G, Blanco E, Buscaglia A, Fortunato S, Marsoni M, Scarcia P, Caretto S, Vannini C, de Pinto MC. Cyclic AMP mediates heat stress response by the control of redox homeostasis and ubiquitin-proteasome system. PLANT, CELL & ENVIRONMENT 2020; 43:2727-2742. [PMID: 32876347 DOI: 10.1111/pce.13878] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 08/22/2020] [Indexed: 06/11/2023]
Abstract
Heat stress (HS), causing impairment in several physiological processes, is one of the most damaging environmental cues for plants. To counteract the harmful effects of high temperatures, plants activate complex signalling networks, indicated as HS response (HSR). Expression of heat shock proteins (HSPs) and adjustment of redox homeostasis are crucial events of HSR, required for thermotolerance. By pharmacological approaches, the involvement of cAMP in triggering plant HSR has been recently proposed. In this study, to investigate the role of cAMP in HSR signalling, tobacco BY-2 cells overexpressing the 'cAMP-sponge', a genetic tool that reduces intracellular cAMP levels, have been used. in vivo cAMP dampening increased HS susceptibility in a HSPs-independent way. The failure in cAMP elevation during HS caused a high accumulation of reactive oxygen species, due to increased levels of respiratory burst oxidase homolog D, decreased activities of catalase and ascorbate peroxidase, as well as down-accumulation of proteins involved in the control of redox homeostasis. In addition, cAMP deficiency impaired proteasome activity and prevented the accumulation of many proteins of ubiquitin-proteasome system (UPS). By a large-scale proteomic approach together with in silico analyses, these UPS proteins were identified in a specific cAMP-dependent network of HSR.
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Affiliation(s)
| | - Guido Domingo
- Department of Biotechnology and Life Science, University of Insubria, Varese, Italy
| | - Emanuela Blanco
- Institute of Biosciences and Bioresources, National Research Council, Bari, Italy
| | - Alessio Buscaglia
- Department of Biology, University of Bari "Aldo Moro", Bari, Italy
- Department of Biotechnology and Life Science, University of Insubria, Varese, Italy
| | | | - Milena Marsoni
- Department of Biotechnology and Life Science, University of Insubria, Varese, Italy
| | - Pasquale Scarcia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Sofia Caretto
- Institute of Sciences of Food Production, CNR, Research Division Lecce, Lecce, Italy
| | - Candida Vannini
- Department of Biotechnology and Life Science, University of Insubria, Varese, Italy
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Protein Degradome of Spinal Cord Injury: Biomarkers and Potential Therapeutic Targets. Mol Neurobiol 2020; 57:2702-2726. [PMID: 32328876 DOI: 10.1007/s12035-020-01916-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 03/31/2020] [Indexed: 12/13/2022]
Abstract
Degradomics is a proteomics sub-discipline whose goal is to identify and characterize protease-substrate repertoires. With the aim of deciphering and characterizing key signature breakdown products, degradomics emerged to define encryptic biomarker neoproteins specific to certain disease processes. Remarkable improvements in structural and analytical experimental methodologies as evident in research investigating cellular behavior in neuroscience and cancer have allowed the identification of specific degradomes, increasing our knowledge about proteases and their regulators and substrates along with their implications in health and disease. A physiologic balance between protein synthesis and degradation is sought with the activation of proteolytic enzymes such as calpains, caspases, cathepsins, and matrix metalloproteinases. Proteolysis is essential for development, growth, and regeneration; however, inappropriate and uncontrolled activation of the proteolytic system renders the diseased tissue susceptible to further neurotoxic processes. In this article, we aim to review the protease-substrate repertoires as well as emerging therapeutic interventions in spinal cord injury at the degradomic level. Several protease substrates and their breakdown products, essential for the neuronal structural integrity and functional capacity, have been characterized in neurotrauma including cytoskeletal proteins, neuronal extracellular matrix glycoproteins, cell junction proteins, and ion channels. Therefore, targeting exaggerated protease activity provides a potentially effective therapeutic approach in the management of protease-mediated neurotoxicity in reducing the extent of damage secondary to spinal cord injury.
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Rao MS, Abd-El-Basset EM. dBcAMP Rescues the Neurons From Degeneration in Kainic Acid-Injured Hippocampus, Enhances Neurogenesis, Learning, and Memory. Front Behav Neurosci 2020; 14:18. [PMID: 32194381 PMCID: PMC7065045 DOI: 10.3389/fnbeh.2020.00018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/24/2020] [Indexed: 01/17/2023] Open
Abstract
Dibutyryl cyclic adenosine monophosphate (dBcAMP) is a cell-permeable synthetic analog of cyclic adenosine monophosphate (cAMP). Although the elevation of cAMP levels was reported to promote the functional recovery in spinal cord injury, its role in neurogenesis or functional recovery after hippocampal injury is unknown. The objective of the study was to investigate the effects of dBcAMP on learning, memory, and hippocampal neurogenesis in the excitotoxically lesioned hippocampus. An excitotoxic lesion was induced in the hippocampi of 4-month-old male BALB/c mice by injecting 0.25 μg/μl into the lateral ventricles of both sides. The lesioned mice (L) were divided into L+dBcAMP and L+phosphate-buffered saline (PBS) groups. Sham surgery (S) was done by the injection of 1 μl of sterile saline into the lateral ventricles. The sham surgery mice were divided into S+dBcAMP and S+PBS groups. Mice in the L+dBcAMP and S+dBcAMP groups were treated with dBcAMP for 1 week (i.p., 50 mg/kg), whereas mice in the L+PBS and S+PBS groups were treated with PBS. The mice in all groups were subjected to water maze and passive avoidance tests at the end of the 4th week. Cresyl violet staining and NeuN and doublecortin immunostaining were done to analyze the morphology and neurogenesis. The water maze learning sessions did not show a significant difference in escape latency between the groups, suggesting an unimpaired learning ability of mice in all groups. The L+dBcAMP mice had significantly short entry latency and higher target quadrant time/distance traveled compared to the L+PBS group, suggesting better memory retention. The L+dBcAMP group had a significantly improved memory retention compared to the L+PBS mice during the passive avoidance test. Morphological studies showed significantly greater adult neurons and increased hippocampal neurogenesis in the hippocampus of mice in the L+dBcAMP group compared to those in the L+PBS group. There was no significant difference between the S+dBcAMP and S+PBS groups in the water maze/passive avoidance tests and the number of neurons. In conclusion, dBcAMP protects the hippocampal neuron from degeneration and enhances hippocampal neurogenesis, learning, and memory.
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Pueraria lobata and Daidzein Reduce Cytotoxicity by Enhancing Ubiquitin-Proteasome System Function in SCA3-iPSC-Derived Neurons. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8130481. [PMID: 31687087 PMCID: PMC6800904 DOI: 10.1155/2019/8130481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/07/2019] [Accepted: 07/23/2019] [Indexed: 12/27/2022]
Abstract
Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion within the ATXN3/MJD1 gene. The expanded CAG repeats encode a polyglutamine (polyQ) tract at the C-terminus of the ATXN3 protein. ATXN3 containing expanded polyQ forms aggregates, leading to subsequent cellular dysfunctions including an impaired ubiquitin-proteasome system (UPS). To investigate the pathogenesis of SCA3 and develop potential therapeutic strategies, we established induced pluripotent stem cell (iPSC) lines from SCA3 patients (SCA3-iPSC). Neurons derived from SCA3-iPSCs formed aggregates that are positive to the polyQ marker 1C2. Treatment with the proteasome inhibitor, MG132, on SCA3-iPSC-derived neurons downregulated proteasome activity, increased production of radical oxygen species (ROS), and upregulated the cleaved caspase 3 level and caspase 3 activity. This increased susceptibility to the proteasome inhibitor can be rescued by a Chinese herbal medicine (CHM) extract NH037 (from Pueraria lobata) and its constituent daidzein via upregulating proteasome activity and reducing protein ubiquitination, oxidative stress, cleaved caspase 3 level, and caspase 3 activity. Our results successfully recapitulate the key phenotypes of the neurons derived from SCA3 patients, as well as indicate the potential of NH037 and daidzein in the treatment for SCA3 patients.
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Abstract
The proteasome degrades most cellular proteins in a controlled and tightly regulated manner and thereby controls many processes, including cell cycle, transcription, signalling, trafficking and protein quality control. Proteasomal degradation is vital in all cells and organisms, and dysfunction or failure of proteasomal degradation is associated with diverse human diseases, including cancer and neurodegeneration. Target selection is an important and well-established way to control protein degradation. In addition, mounting evidence indicates that cells adjust proteasome-mediated degradation to their needs by regulating proteasome abundance through the coordinated expression of proteasome subunits and assembly chaperones. Central to the regulation of proteasome assembly is TOR complex 1 (TORC1), which is the master regulator of cell growth and stress. This Review discusses how proteasome assembly and the regulation of proteasomal degradation are integrated with cellular physiology, including the interplay between the proteasome and autophagy pathways. Understanding these mechanisms has potential implications for disease therapy, as the misregulation of proteasome function contributes to human diseases such as cancer and neurodegeneration.
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Schaler AW, Myeku N. Cilostazol, a phosphodiesterase 3 inhibitor, activates proteasome-mediated proteolysis and attenuates tauopathy and cognitive decline. Transl Res 2018; 193:31-41. [PMID: 29232559 PMCID: PMC10075247 DOI: 10.1016/j.trsl.2017.11.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 10/25/2017] [Accepted: 11/16/2017] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease and several variants of frontotemporal degeneration including progressive supranuclear palsy and corticobasal degeneration are characterized by the accumulation of abnormal tau protein into aggregates. Most proteins, including tau, are degraded via the ubiquitin proteasome system, but when abnormal tau accumulates, the function of 26S proteasomes is downregulated. The negative effect of tau aggregates on the function of the proteasome can have deleterious consequences on protein homeostasis and disease progression. Developing therapies aimed at clearing abnormal tau are thus of considerable interest. In the present study, we investigated the effect of cilostazol, an FDA-approved selective phosphodiesterase 3 inhibitor, on a mouse model of tauopathy (line rTg4510). Administration of cilostazol for 30 days enhanced proteasome function via the cyclic adenosine 3',5'-monophosphate/protein kinase A pathway and attenuated tauopathy and cognitive decline in rTg4510 mice. These results suggest that cilostazol, or other FDA-approved drugs acting via the same pathway, has the potential to be repurposed for the treatment of patients with early-stage tauopathy.
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Affiliation(s)
- Ari W Schaler
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY
| | - Natura Myeku
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY.
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16
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Myeku N, Duff KE. Targeting the 26S Proteasome To Protect Against Proteotoxic Diseases. Trends Mol Med 2017; 24:18-29. [PMID: 29233753 DOI: 10.1016/j.molmed.2017.11.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/21/2017] [Accepted: 11/21/2017] [Indexed: 12/16/2022]
Abstract
Aggregates of misfolded proteins can compromise the function of the 26S proteasome complex, leaving neurons susceptible to accelerated and impaired protein homeostasis, thereby contributing to the pathogenesis of neurodegeneration. Strategies aimed at enhancing the function of the 26S proteasome via phosphorylation of key subunit epitopes have been effective in reducing protein aggregates in mouse models of disease. We discuss how phosphodiesterase (PDE) inhibitors and G protein-coupled receptor (GPCR)-targeted drugs might be considered as candidate therapeutics, acting on second messenger signal transduction. The range of candidates might address the need for region-, cell-, or even cellular compartment-specific modulation. Given the array of clinical and experimental drugs targeting cAMP/cGMP signaling, we propose that proteasome activators targeting secondary messengers might be exploited as novel agents for the treatment or prevention of some neurodegenerative diseases.
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Affiliation(s)
- Natura Myeku
- Department of Pathology and Cell Biology, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
| | - Karen E Duff
- Department of Pathology and Cell Biology, The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA; Division of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY, USA.
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17
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Sun YY, Zhang WJ, Dong CL, Zhang XF, Ji J, Wang X, Wang L, Hu WL, Du WJ, Cui CL, Zhang CF, Li F, Wang CZ, Yuan CS. Baicalin Alleviates Nitroglycerin-induced Migraine in Rats via the Trigeminovascular System. Phytother Res 2017; 31:899-905. [DOI: 10.1002/ptr.5811] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 03/07/2017] [Accepted: 03/16/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Yu-Yao Sun
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Wen-Jun Zhang
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Cui-Lan Dong
- The People's Hospital of Zhangqiu; Zhangqiu 250200 China
| | - Xiao-Fan Zhang
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Jun Ji
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Xue Wang
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Ling Wang
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Wan-Li Hu
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Wen-Juan Du
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Cheng-Long Cui
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Chun-Feng Zhang
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
- Tang Center of Herbal Medicine Research and Department of Anesthesia & Critical Care; The University of Chicago; Chicago IL 60637 USA
| | - Fei Li
- State Key Laboratory of Natural Medicines; China Pharmaceutical University; Nanjing JS 210009 China
| | - Chong-Zhi Wang
- Tang Center of Herbal Medicine Research and Department of Anesthesia & Critical Care; The University of Chicago; Chicago IL 60637 USA
| | - Chun-Su Yuan
- Tang Center of Herbal Medicine Research and Department of Anesthesia & Critical Care; The University of Chicago; Chicago IL 60637 USA
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18
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Guo X, Huang X, Chen MJ. Reversible phosphorylation of the 26S proteasome. Protein Cell 2017; 8:255-272. [PMID: 28258412 PMCID: PMC5359188 DOI: 10.1007/s13238-017-0382-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/26/2017] [Indexed: 01/09/2023] Open
Abstract
The 26S proteasome at the center of the ubiquitin-proteasome system (UPS) is essential for virtually all cellular processes of eukaryotes. A common misconception about the proteasome is that, once made, it remains as a static and uniform complex with spontaneous and constitutive activity for protein degradation. Recent discoveries have provided compelling evidence to support the exact opposite insomuch as the 26S proteasome undergoes dynamic and reversible phosphorylation under a variety of physiopathological conditions. In this review, we summarize the history and current understanding of proteasome phosphorylation, and advocate the idea of targeting proteasome kinases/phosphatases as a new strategy for clinical interventions of several human diseases.
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Affiliation(s)
- Xing Guo
- The Life Sciences Institute of Zhejiang University, Hangzhou, 310058, China.
| | - Xiuliang Huang
- Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Mark J Chen
- Department of Bioinformatics and Computational Biology, Genentech Inc., South San Francisco, CA, 94080, USA
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19
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Hansen SK, Stummann TC, Borland H, Hasholt LF, Tümer Z, Nielsen JE, Rasmussen MA, Nielsen TT, Daechsel JCA, Fog K, Hyttel P. Induced pluripotent stem cell - derived neurons for the study of spinocerebellar ataxia type 3. Stem Cell Res 2016; 17:306-317. [PMID: 27596958 DOI: 10.1016/j.scr.2016.07.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 06/09/2016] [Accepted: 07/18/2016] [Indexed: 11/29/2022] Open
Abstract
The neurodegenerative disease spinocerebellar ataxia type 3 (SCA3) is caused by a CAG-repeat expansion in the ATXN3 gene. In this study, induced pluripotent stem cell (iPSC) lines were established from two SCA3 patients. Dermal fibroblasts were reprogrammed using an integration-free method and the resulting SCA3 iPSCs were differentiated into neurons. These neuronal lines harbored the disease causing mutation, expressed comparable levels of several neuronal markers and responded to the neurotransmitters, glutamate/glycine, GABA and acetylcholine. Additionally, all neuronal cultures formed networks displaying synchronized spontaneous calcium oscillations within 28days of maturation, and expressed the mature neuronal markers NeuN and Synapsin 1 implying a relatively advanced state of maturity, although not comparable to that of the adult human brain. Interestingly, we were not able to recapitulate the glutamate-induced ataxin-3 aggregation shown in a previously published iPSC-derived SCA3 model. In conclusion, we have generated a panel of SCA3 patient iPSCs and a robust protocol to derive neurons of relatively advanced maturity, which could potentially be valuable for the study of SCA3 disease mechanisms.
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Affiliation(s)
- Susanne K Hansen
- Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Groennegårdsvej 7, 1870 Frb C, Denmark; H. Lundbeck A/S, Ottiliavej 9, Valby 2500, Denmark.
| | | | | | - Lis F Hasholt
- Institute of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 N, Denmark
| | - Zeynep Tümer
- Applied Human Molecular Genetics, Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Gl. Landevej 7, Glostrup 2600, Denmark
| | - Jørgen E Nielsen
- Institute of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 N, Denmark; Neurogenetics Clinic & Research Laboratory, Danish Dementia Research Centre, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Mikkel A Rasmussen
- Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Groennegårdsvej 7, 1870 Frb C, Denmark
| | - Troels T Nielsen
- Neurogenetics Clinic & Research Laboratory, Danish Dementia Research Centre, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | | | - Karina Fog
- H. Lundbeck A/S, Ottiliavej 9, Valby 2500, Denmark
| | - Poul Hyttel
- Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Groennegårdsvej 7, 1870 Frb C, Denmark
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21
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Gong B, Radulovic M, Figueiredo-Pereira ME, Cardozo C. The Ubiquitin-Proteasome System: Potential Therapeutic Targets for Alzheimer's Disease and Spinal Cord Injury. Front Mol Neurosci 2016; 9:4. [PMID: 26858599 PMCID: PMC4727241 DOI: 10.3389/fnmol.2016.00004] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 01/07/2016] [Indexed: 01/20/2023] Open
Abstract
The ubiquitin-proteasome system (UPS) is a crucial protein degradation system in eukaryotes. Herein, we will review advances in the understanding of the role of several proteins of the UPS in Alzheimer’s disease (AD) and functional recovery after spinal cord injury (SCI). The UPS consists of many factors that include E3 ubiquitin ligases, ubiquitin hydrolases, ubiquitin and ubiquitin-like molecules, and the proteasome itself. An extensive body of work links UPS dysfunction with AD pathogenesis and progression. More recently, the UPS has been shown to have vital roles in recovery of function after SCI. The ubiquitin hydrolase (Uch-L1) has been proposed to increase cellular levels of mono-ubiquitin and hence to increase rates of protein turnover by the UPS. A low Uch-L1 level has been linked with Aβ accumulation in AD and reduced neuroregeneration after SCI. One likely mechanism for these beneficial effects of Uch-L1 is reduced turnover of the PKA regulatory subunit and consequently, reduced signaling via CREB. The neuron-specific F-box protein Fbx2 ubiquitinates β-secretase thus targeting it for proteasomal degradation and reducing generation of Aβ. Both Uch-L1 and Fbx2 improve synaptic plasticity and cognitive function in mouse AD models. The role of Fbx2 after SCI has not been examined, but abolishing ß-secretase reduces neuronal recovery after SCI, associated with reduced myelination. UBB+1, which arises through a frame-shift mutation in the ubiquitin gene that adds 19 amino acids to the C-terminus of ubiquitin, inhibits proteasomal function and is associated with increased neurofibrillary tangles in patients with AD, Pick’s disease and Down’s syndrome. These advances in understanding of the roles of the UPS in AD and SCI raise new questions but, also, identify attractive and exciting targets for potential, future therapeutic interventions.
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Affiliation(s)
- Bing Gong
- Department of Medicine, Mount Sinai School of MedicineNew York, NY, USA; Medicine, James J. Peters Veteran Affairs Medical CenterBronx, NY, USA
| | - Miroslav Radulovic
- Department of Medicine, Mount Sinai School of MedicineNew York, NY, USA; Medicine, James J. Peters Veteran Affairs Medical CenterBronx, NY, USA; National Center of Excellence for the Medical Consequences of Spinal Cord Injury (SCI)Bronx, NY, USA
| | - Maria E Figueiredo-Pereira
- Department of Biological Sciences, Hunter College, and the Graduate School and University Center, The City University of New York New York, NY, USA
| | - Christopher Cardozo
- Department of Medicine, Mount Sinai School of MedicineNew York, NY, USA; Medicine, James J. Peters Veteran Affairs Medical CenterBronx, NY, USA; National Center of Excellence for the Medical Consequences of Spinal Cord Injury (SCI)Bronx, NY, USA
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22
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Pentoxifylline triggers autophagy via ER stress response that interferes with Pentoxifylline induced apoptosis in human melanoma cells. Biochem Pharmacol 2016; 103:17-28. [PMID: 26793997 DOI: 10.1016/j.bcp.2015.12.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 12/22/2015] [Indexed: 12/17/2022]
Abstract
Pentoxifylline (PTX), a non-specific phosphodiesterase inhibitor is known to inhibit the growth of various cancer cells including melanoma. Here in this study, we have found that PTX induces autophagy in human melanoma cell lines (A375 and MeWo). Induction of autophagy is associated with the increase in Atg5 expression as knockdown of Atg5 effectively inhibited PTX mediated autophagy. A decrease in mTOR activation was also observed after PTX treatment. We observed that autophagy was activated as a downstream effector mechanism of ER stress induced by PTX. ER stress response was confirmed by upregulation of IRE-1α, GRP78 and CHOP expression. PTX treatment also resulted in an increase in intracellular calcium (Ca(2+)) level. Ca(2+) is the central player as blocking Ca(2+) by intracellular calcium chelator (BAPTA-AM) effectively inhibited the PTX induced ER stress response as well as autophagy. Moreover, silencing of CHOP also resulted in autophagy inhibition with a decrease in Atg5 expression. Collectively, PTX triggers ER stress response followed by induction of autophagy via involvement of Ca(2+)→CHOP→Atg5 signalling cascade. Interestingly, inhibition of intracellular calcium level by BAPTA-AM significantly increased PTX mediated cell death by augmenting intrinsic apoptotic pathway. Inhibition of autophagy by the ATG5 siRNA and pharmacological inhibitor, chloroquine also enhances PTX induced cell death. Taken together, our results clearly indicate that activation of ER stress response and autophagy provides resistance to PTX mediated apoptosis, and thus, interferes with the anticancer activity of PTX in human melanoma cells.
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Tau-driven 26S proteasome impairment and cognitive dysfunction can be prevented early in disease by activating cAMP-PKA signaling. Nat Med 2015; 22:46-53. [PMID: 26692334 DOI: 10.1038/nm.4011] [Citation(s) in RCA: 308] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 11/17/2015] [Indexed: 12/12/2022]
Abstract
The ubiquitin proteasome system (UPS) degrades misfolded proteins including those implicated in neurodegenerative diseases. We investigated the effects of tau accumulation on proteasome function in a mouse model of tauopathy and in a cross to a UPS reporter mouse (line Ub-G76V-GFP). Accumulation of insoluble tau was associated with a decrease in the peptidase activity of brain 26S proteasomes, higher levels of ubiquitinated proteins and undegraded Ub-G76V-GFP. 26S proteasomes from mice with tauopathy were physically associated with tau and were less active in hydrolyzing ubiquitinated proteins, small peptides and ATP. 26S proteasomes from normal mice incubated with recombinant oligomers or fibrils also showed lower hydrolyzing capacity in the same assays, implicating tau as a proteotoxin. Administration of an agent that activates cAMP-protein kinase A (PKA) signaling led to attenuation of proteasome dysfunction, probably through proteasome subunit phosphorylation. In vivo, this led to lower levels of aggregated tau and improvements in cognitive performance.
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cAMP-induced phosphorylation of 26S proteasomes on Rpn6/PSMD11 enhances their activity and the degradation of misfolded proteins. Proc Natl Acad Sci U S A 2015; 112:E7176-85. [PMID: 26669444 DOI: 10.1073/pnas.1522332112] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although rates of protein degradation by the ubiquitin-proteasome pathway (UPS) are determined by their rates of ubiquitination, we show here that the proteasome's capacity to degrade ubiquitinated proteins is also tightly regulated. We studied the effects of cAMP-dependent protein kinase (PKA) on proteolysis by the UPS in several mammalian cell lines. Various agents that raise intracellular cAMP and activate PKA (activators of adenylate cyclase or inhibitors of phosphodiesterase 4) promoted degradation of short-lived (but not long-lived) cell proteins generally, model UPS substrates having different degrons, and aggregation-prone proteins associated with major neurodegenerative diseases, including mutant FUS (Fused in sarcoma), SOD1 (superoxide dismutase 1), TDP43 (TAR DNA-binding protein 43), and tau. 26S proteasomes purified from these treated cells or from control cells and treated with PKA degraded ubiquitinated proteins, small peptides, and ATP more rapidly than controls, but not when treated with protein phosphatase. Raising cAMP levels also increased amounts of doubly capped 26S proteasomes. Activated PKA phosphorylates the 19S subunit, Rpn6/PSMD11 (regulatory particle non-ATPase 6/proteasome subunit D11) at Ser14. Overexpression of a phosphomimetic Rpn6 mutant activated proteasomes similarly, whereas a nonphosphorylatable mutant decreased activity. Thus, proteasome function and protein degradation are regulated by cAMP through PKA and Rpn6, and activation of proteasomes by this mechanism may be useful in treating proteotoxic diseases.
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25
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Repeated Mu-Opioid Exposure Induces a Novel Form of the Hyperalgesic Priming Model for Transition to Chronic Pain. J Neurosci 2015; 35:12502-17. [PMID: 26354917 DOI: 10.1523/jneurosci.1673-15.2015] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The primary afferent nociceptor was used as a model system to study mechanisms of pain induced by chronic opioid administration. Repeated intradermal injection of the selective mu-opioid receptor (MOR) agonist DAMGO induced mechanical hyperalgesia and marked prolongation of prostaglandin E2 (PGE2) hyperalgesia, a key feature of hyperalgesic priming. However, in contrast to prior studies of priming induced by receptor-mediated (i.e., TNFα, NGF, or IL-6 receptor) or direct activation of protein kinase Cε (PKCε), the pronociceptive effects of PGE2 in DAMGO-treated rats demonstrated the following: (1) rapid induction (4 h compared with 3 d); (2) protein kinase A (PKA), rather than PKCε, dependence; (3) prolongation of hyperalgesia induced by an activator of PKA, 8-bromo cAMP; (4) failure to be reversed by a protein translation inhibitor; (5) priming in females as well as in males; and (6) lack of dependence on the isolectin B4-positive nociceptor. These studies demonstrate a novel form of hyperalgesic priming induced by repeated administration of an agonist at the Gi-protein-coupled MOR to the peripheral terminal of the nociceptor. Significance statement: The current study demonstrates the molecular mechanisms involved in the sensitization of nociceptors produced by repeated activation of mu-opioid receptors and contributes to our understanding of the painful condition observed in patients submitted to chronic use of opioids.
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Chou AH, Chen YL, Chiu CC, Yuan SJ, Weng YH, Yeh TH, Lin YL, Fang JM, Wang HL. T1-11 and JMF1907 ameliorate polyglutamine-expanded ataxin-3-induced neurodegeneration, transcriptional dysregulation and ataxic symptom in the SCA3 transgenic mouse. Neuropharmacology 2015; 99:308-17. [PMID: 26254860 DOI: 10.1016/j.neuropharm.2015.08.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 08/04/2015] [Accepted: 08/04/2015] [Indexed: 11/24/2022]
Abstract
More studies are required to develop therapeutic agents for treating spinocerebellar ataxia type 3 (SCA3), which is caused by mutant polyglutamine-expanded ataxin-3 and is the most prevalent subtype of spinocerebellar ataxias. T1-11 [N6-(4-Hydroxybenzyl) adenosine], isolated from a Chinese medicinal herb Gastordia elata, is an adenosine A2A receptor agonist. SCA3 and Huntington's disease (HD) belong to a family of polyglutamine neurodegenerative diseases. T1-11 exerted a therapeutic effect on HD transgenic mouse by decreasing protein level of polyglutamine-expanded huntingtin in the striatum. In the present study, we test the possibility that T1-11 or JMF1907 [N6-(3-Indolylethyl) adenosine], a synthetic analog of T1-11, alleviates pontine neuronal death, cerebellar transcriptional downregulation and ataxic symptom in the SCA3 transgenic mouse expressing HA-tagged polyglutamine-expanded ataxin-3-Q79 (ataxin-3-Q79HA). Daily oral administration of T1-11 or JMF1907 prevented neuronal death of pontine nuclei in the SCA3 mouse with a dose-dependent manner. Oral application of T1-11 or JMF1907 reversed mutant ataxin-3-Q79-induced cerebellar transcriptional repression in the SCA3 transgenic mouse. T1-11 or JMF1907 ameliorated the symptom of motor incoordination displayed by SCA3 mouse. Oral administration of T1-11 or JMF1907 significantly decreased protein level of ataxin-3-Q79HA in the pontine nuclei or cerebellum of SCA3 mouse. T1-11 or JMF1907 significantly augmented the chymotrypsin-like activity of proteasome in the pontine nuclei or cerebellum of SCA3 mouse. Our results suggests that T1-11 and JMF1907 alleviate pontine neuronal death, cerebellar transcriptional downregulation and ataxic symptom of SCA3 transgenic mouse by augmenting the proteasome activity and reducing the protein level of polyglutamine-expanded ataxin-3-Q79 in the pontine nuclei and cerebellum.
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Affiliation(s)
- An-Hsun Chou
- Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC
| | - Ying-Ling Chen
- Chang Gung University of Science and Technology, Taoyuan, Taiwan, ROC
| | - Ching-Chi Chiu
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC
| | - Shin-Je Yuan
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan, ROC
| | - Yi-Hsin Weng
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC; Department of Neurology, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC; College of Medicine, Chang Gung University, Taoyuan, Taiwan, ROC
| | - Tu-Hsueh Yeh
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC; Department of Neurology, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC; College of Medicine, Chang Gung University, Taoyuan, Taiwan, ROC
| | - Yun-Lian Lin
- National Research Institute of Chinese Medicine, Taipei, Taiwan, ROC
| | - Jim-Min Fang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan, ROC
| | - Hung-Li Wang
- Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan, ROC; Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan, ROC; Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan, ROC.
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Abstract
Three theories of regeneration dominate neuroscience today, all purporting to explain why the adult central nervous system (CNS) cannot regenerate. One theory proposes that Nogo, a molecule expressed by myelin, prevents axonal growth. The second theory emphasizes the role of glial scars. The third theory proposes that chondroitin sulfate proteoglycans (CSPGs) prevent axon growth. Blockade of Nogo, CSPG, and their receptors indeed can stop axon growth in vitro and improve functional recovery in animal spinal cord injury (SCI) models. These therapies also increase sprouting of surviving axons and plasticity. However, many investigators have reported regenerating spinal tracts without eliminating Nogo, glial scar, or CSPG. For example, many motor and sensory axons grow spontaneously in contused spinal cords, crossing gliotic tissue and white matter surrounding the injury site. Sensory axons grow long distances in injured dorsal columns after peripheral nerve lesions. Cell transplants and treatments that increase cAMP and neurotrophins stimulate motor and sensory axons to cross glial scars and to grow long distances in white matter. Genetic studies deleting all members of the Nogo family and even the Nogo receptor do not always improve regeneration in mice. A recent study reported that suppressing the phosphatase and tensin homolog (PTEN) gene promotes prolific corticospinal tract regeneration. These findings cannot be explained by the current theories proposing that Nogo and glial scars prevent regeneration. Spinal axons clearly can and will grow through glial scars and Nogo-expressing tissue under some circumstances. The observation that deleting PTEN allows corticospinal tract regeneration indicates that the PTEN/AKT/mTOR pathway regulates axonal growth. Finally, many other factors stimulate spinal axonal growth, including conditioning lesions, cAMP, glycogen synthetase kinase inhibition, and neurotrophins. To explain these disparate regenerative phenomena, I propose that the spinal cord has evolved regenerative mechanisms that are normally suppressed by multiple extrinsic and intrinsic factors but can be activated by injury, mediated by the PTEN/AKT/mTOR, cAMP, and GSK3b pathways, to stimulate neural growth and proliferation.
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Affiliation(s)
- Wise Young
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, State University of New Jersey, Piscataway, NJ, USA
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28
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Shivers KY, Nikolopoulou A, Machlovi SI, Vallabhajosula S, Figueiredo-Pereira ME. PACAP27 prevents Parkinson-like neuronal loss and motor deficits but not microglia activation induced by prostaglandin J2. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1707-19. [PMID: 24970746 DOI: 10.1016/j.bbadis.2014.06.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 06/11/2014] [Accepted: 06/17/2014] [Indexed: 12/16/2022]
Abstract
Neuroinflammation is a major risk factor in Parkinson's disease (PD). Alternative approaches are needed to treat inflammation, as anti-inflammatory drugs such as NSAIDs that inhibit cyclooxygenase-2 (COX-2) can produce devastating side effects, including heart attack and stroke. New therapeutic strategies that target factors downstream of COX-2, such as prostaglandin J2 (PGJ2), hold tremendous promise because they will not alter the homeostatic balance offered by COX-2 derived prostanoids. In the current studies, we report that repeated microinfusion of PGJ2 into the substantia nigra of non-transgenic mice, induces three stages of pathology that mimic the slow-onset cellular and behavioral pathology of PD: mild (one injection) when only motor deficits are detectable, intermediate (two injections) when neuronal and motor deficits as well as microglia activation are detectable, and severe (four injections) when dopaminergic neuronal loss is massive accompanied by microglia activation and motor deficits. Microglia activation was evaluated in vivo by positron emission tomography (PET) with [(11)C](R)PK11195 to provide a regional estimation of brain inflammation. PACAP27 reduced dopaminergic neuronal loss and motor deficits induced by PGJ2, without preventing microglia activation. The latter could be problematic in that persistent microglia activation can exert long-term deleterious effects on neurons and behavior. In conclusion, this PGJ2-induced mouse model that mimics in part chronic inflammation, exhibits slow-onset PD-like pathology and is optimal for testing diagnostic tools such as PET, as well as therapies designed to target the integrated signaling across neurons and microglia, to fully benefit patients with PD.
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Affiliation(s)
- Kai-Yvonne Shivers
- Department of Biological Sciences, Hunter College, Graduate School and University Center, CUNY, New York, NY 10065, USA
| | - Anastasia Nikolopoulou
- Department of Radiology, Citigroup Biomedical Imaging Center, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
| | - Saima Ishaq Machlovi
- Department of Biological Sciences, Hunter College, Graduate School and University Center, CUNY, New York, NY 10065, USA
| | - Shankar Vallabhajosula
- Department of Radiology, Citigroup Biomedical Imaging Center, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
| | - Maria E Figueiredo-Pereira
- Department of Biological Sciences, Hunter College, Graduate School and University Center, CUNY, New York, NY 10065, USA.
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Coffey EE, Beckel JM, Laties AM, Mitchell CH. Lysosomal alkalization and dysfunction in human fibroblasts with the Alzheimer's disease-linked presenilin 1 A246E mutation can be reversed with cAMP. Neuroscience 2014; 263:111-24. [PMID: 24418614 PMCID: PMC4028113 DOI: 10.1016/j.neuroscience.2014.01.001] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 12/30/2013] [Accepted: 01/02/2014] [Indexed: 12/27/2022]
Abstract
Mutation in presenilin 1 (PS1) is one of the leading causes of familial Alzheimer's disease (fAD). PS1 mutation exacerbates the autophagic and lysosomal pathology in AD patients, leading to accumulation of partially degraded material in bloated lysosomes and autophagosomes - a pathology that bears some resemblance to other diseases characterized by elevated lysosomal pH, like age-related macular degeneration. In this study, we examined the effect of the PS1-fAD mutation A246E on lysosomal pH and lysosomal function, and asked whether restoration of lysosomal pH could reverse some of these changes. Lysosomal pH was elevated by 0.2-0.3 pH units in human fibroblasts with the PS1-fAD mutation. The lysosomal alkalization in PS1-fAD fibroblasts was supported by a reduction in the pH-dependent cleavage of cathepsin D and by a reduction in binding of boron-dipyrromethene (BODIPY) FL-pepstatin A to the cathepsin D active site. PS1-fAD cells had increased LC3B-II/-I ratios and p62 levels, consistent with impaired lysosomal degradation and analogous to changes induced by lysosomal alkalinization with chloroquine. PS1-fAD fibroblasts had increased expression of ATP6V1B2, ATG5, BECN1 TFEB mRNA, and of ATP6V1B2, ATG5 and beclin at the protein level, consistent with chronic impairment of autophagic and lysosomal functions in the mutant cells. Critically, cyclic adenosine monophosphate (cAMP) treatment reacidified lysosomal pH in mutant PS1-fAD; cAMP also increased the availability of active cathepsin D and lowered the LC3B-II/-I ratio. These results confirm a small elevation in the lysosomal pH of human PS1-fAD fibroblasts, demonstrate that this lysosomal alkalization is associated with chronic changes in autophagy and degradation, and suggest that treatment to reacidify the lysosomes with cAMP can reverse these changes.
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Affiliation(s)
- E E Coffey
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - J M Beckel
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - A M Laties
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - C H Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, United States; Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, United States.
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Huang H, Wang H, Figueiredo-Pereira ME. Regulating the ubiquitin/proteasome pathway via cAMP-signaling: neuroprotective potential. Cell Biochem Biophys 2014; 67:55-66. [PMID: 23686612 DOI: 10.1007/s12013-013-9628-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The cAMP-signaling pathway has been under intensive investigation for decades. It is a wonder that such a small simple molecule like cAMP can modulate a vast number of diverse processes in different types of cells. The ubiquitous involvement of cAMP-signaling in a variety of cellular events requires tight spatial and temporal control of its generation, propagation, compartmentalization, and elimination. Among the various steps of the cAMP-signaling pathway, G-protein-coupled receptors, adenylate cyclases, phosphodiesterases, the two major cAMP targets, i.e., protein kinase A and exchange protein activated by cAMP, as well as the A-kinase anchoring proteins, are potential targets for drug development. Herein we review the recent progress on the regulation and manipulation of different steps of the cAMP-signaling pathway. We end by focusing on the emerging role of cAMP-signaling in modulating protein degradation via the ubiquitin/proteasome pathway. New discoveries on the regulation of the ubiquitin/proteasome pathway by cAMP-signaling support the development of new therapeutic approaches to prevent proteotoxicity in chronic neurodegenerative disorders and other human disease conditions associated with impaired protein turnover by the ubiquitin/proteasome pathway and the accumulation of ubiquitin-protein aggregates.
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Affiliation(s)
- He Huang
- Department of Biological Sciences, Hunter College and Graduate Center, City University of New York, 695 Park Avenue, New York, NY 10065, USA
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Time-resolved characterization of cAMP/PKA-dependent signaling reveals that platelet inhibition is a concerted process involving multiple signaling pathways. Blood 2013; 123:e1-e10. [PMID: 24324209 DOI: 10.1182/blood-2013-07-512384] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
One of the most important physiological platelet inhibitors is endothelium-derived prostacyclin which stimulates the platelet cyclic adenosine monophosphate/protein kinase A (cAMP/PKA)-signaling cascade and inhibits virtually all platelet-activating key mechanisms. Using quantitative mass spectrometry, we analyzed time-resolved phosphorylation patterns in human platelets after treatment with iloprost, a stable prostacyclin analog, for 0, 10, 30, and 60 seconds to characterize key mediators of platelet inhibition and activation in 3 independent biological replicates. We quantified over 2700 different phosphorylated peptides of which 360 were significantly regulated upon stimulation. This comprehensive and time-resolved analysis indicates that platelet inhibition is a multipronged process involving different kinases and phosphatases as well as many previously unanticipated proteins and pathways.
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