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Emmerich T, Abdullah L, Crynen G, Dretsch M, Evans J, Ait-Ghezala G, Reed J, Montague H, Chaytow H, Mathura V, Martin J, Pelot R, Ferguson S, Bishop A, Phillips J, Mullan M, Crawford F. Plasma Lipidomic Profiling in a Military Population of Mild Traumatic Brain Injury and Post-Traumatic Stress Disorder with Apolipoprotein E ɛ4-Dependent Effect. J Neurotrauma 2016; 33:1331-48. [PMID: 26714394 DOI: 10.1089/neu.2015.4061] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In the military population, there is high comorbidity between mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) due to the inherent risk of psychological trauma associated with combat. These disorders present with long-term neurological dysfunction and remain difficult to diagnose due to their comorbidity and overlapping clinical presentation. Therefore, we performed cross-sectional analysis of blood samples from demographically matched soldiers (total, n = 120) with mTBI, PTSD, and mTBI+PTSD and those who were considered cognitively and psychologically normal. Soldiers were genotyped for apolipoprotein E (APOE) ɛ4, and phospholipids (PL) were examined using liquid chromatography/mass spectrometry analysis. We observed significantly lower levels of several major PL classes in TBI, PTSD, and TBI+PTSD, compared with controls. PTSD severity analysis revealed that significant PL decreases were primarily restricted to the moderate-to-severe PTSD group. An examination of the degree of unsaturation showed that monounsaturated fatty acid-containing phosphatidylcholine (PC) and phosphatidylinositol (PI) species were lower in the TBI and TBI+PTSD groups. However, these PLs were unaltered among PTSD subjects, compared with controls. Similarly, ether PC (ePC) levels were lower in PTSD and TBI+PTSD subjects, relative to controls. Ratios of arachidonic acid (AA) to docosahexaenoic acid (DHA)-containing species were significantly decreased within PC and phosphatidylethanolamine (PE) classes. APOE ɛ4 (+) subjects exhibited higher PL levels than their APOE ɛ4 (-) counterparts within the same diagnostic groups. These findings suggest that PL profiles, together with APOE genotyping, could potentially aid to differentiate diagnosis of mTBI and PTSD and warrant further validation. In conclusion, PL profiling may facilitate clinical diagnosis of mTBI and PTSD currently hindered by comorbid pathology and overlapping symptomology of these two conditions.
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Affiliation(s)
- Tanja Emmerich
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | - Laila Abdullah
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | - Gogce Crynen
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
| | - Michael Dretsch
- 4 National Intrepid Center of Excellence, Walter Reed National Military Medical Center , Bethesda, Maryland
- 5 United States Army Aeromedical Research Laboratory , Rucker, Alabama
| | | | - Ghania Ait-Ghezala
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | - Jon Reed
- 1 The Roskamp Institute , Sarasota, Florida
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | | | | | - Venkatarajan Mathura
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | | | - Robert Pelot
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | - Scott Ferguson
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
| | | | | | - Michael Mullan
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
| | - Fiona Crawford
- 1 The Roskamp Institute , Sarasota, Florida
- 2 The Open University , Buckinghamshire, United Kingdom
- 3 James A. Haley Veteran's Hospital , Tampa, Florida
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2
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Carlson SW, Yan H, Ma M, Li Y, Henchir J, Dixon CE. Traumatic Brain Injury Impairs Soluble N-Ethylmaleimide-Sensitive Factor Attachment Protein Receptor Complex Formation and Alters Synaptic Vesicle Distribution in the Hippocampus. J Neurotrauma 2015; 33:113-21. [PMID: 25923735 DOI: 10.1089/neu.2014.3839] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) impairs neuronal function and can culminate in lasting cognitive impairment. While impaired neurotransmitter release has been well established after experimental TBI, little is understood about the mechanisms underlying this consequence. In the synapse, vesicular docking and neurotransmitter release requires the formation of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex. Impairments in vesicle docking, and alterations in SNARE complex formation are associated with impaired neurotransmitter release. We hypothesized that TBI reduces SNARE complex formation and disrupts synaptic vesicle distribution in the hippocampus. To examine the effect of TBI on the SNARE complex, rats were subjected to controlled cortical impact (CCI) or sham injury, and the brains were assessed at 6 h, 1 d, one week, two weeks, or four weeks post-injury. Immunoblotting of hippocampal homogenates revealed significantly reduced SNARE complex formation at one week and two weeks post-injury. To assess synaptic vesicles distribution, rats received CCI or sham injury and the brains were processed for transmission electron microscopy at one week post-injury. Synapses in the hippocampus were imaged at 100k magnification, and vesicle distribution was assessed in pre-synaptic terminals at the active zone. CCI resulted in a significant reduction in vesicle number within 150 nm of the active zone. These findings provide the first evidence of TBI-induced impairments in synaptic vesicle docking, and suggest that reductions in the pool of readily releasable vesicles and impaired SNARE complex formation are two novel mechanisms contributing to impaired neurotransmission after TBI.
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Affiliation(s)
- Shaun W Carlson
- Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Hong Yan
- Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Michelle Ma
- Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Youming Li
- Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Jeremy Henchir
- Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - C Edward Dixon
- Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh , Pittsburgh, Pennsylvania
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Merlo L, Cimino F, Angileri FF, La Torre D, Conti A, Cardali SM, Saija A, Germanò A. Alteration in synaptic junction proteins following traumatic brain injury. J Neurotrauma 2015; 31:1375-85. [PMID: 24661152 DOI: 10.1089/neu.2014.3385] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Extensive research and scientific efforts have been focused on the elucidation of the pathobiology of cellular and axonal damage following traumatic brain injury (TBI). Conversely, few studies have specifically addressed the issue of synaptic dysfunction. Synaptic junction proteins may be involved in post-TBI alterations, leading to synaptic loss or disrupted plasticity. A Synapse Protein Database on synapse ontology identified 109 domains implicated in synaptic activities and over 5000 proteins, but few of these demonstrated to play a role in the synaptic dysfunction after TBI. These proteins are involved in neuroplasticity and neuromodulation and, most importantly, may be used as novel neuronal markers of TBI for specific intervention.
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Affiliation(s)
- Lucia Merlo
- 1 Department of Neurosciences, University of Messina , Messina, Italy
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Bramlett HM, Dietrich WD. Long-Term Consequences of Traumatic Brain Injury: Current Status of Potential Mechanisms of Injury and Neurological Outcomes. J Neurotrauma 2014; 32:1834-48. [PMID: 25158206 DOI: 10.1089/neu.2014.3352] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Traumatic brain injury (TBI) is a significant clinical problem with few therapeutic interventions successfully translated to the clinic. Increased importance on the progressive, long-term consequences of TBI have been emphasized, both in the experimental and clinical literature. Thus, there is a need for a better understanding of the chronic consequences of TBI, with the ultimate goal of developing novel therapeutic interventions to treat the devastating consequences of brain injury. In models of mild, moderate, and severe TBI, histopathological and behavioral studies have emphasized the progressive nature of the initial traumatic insult and the involvement of multiple pathophysiological mechanisms, including sustained injury cascades leading to prolonged motor and cognitive deficits. Recently, the increased incidence in age-dependent neurodegenerative diseases in this patient population has also been emphasized. Pathomechanisms felt to be active in the acute and long-term consequences of TBI include excitotoxicity, apoptosis, inflammatory events, seizures, demyelination, white matter pathology, as well as decreased neurogenesis. The current article will review many of these pathophysiological mechanisms that may be important targets for limiting the chronic consequences of TBI.
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Affiliation(s)
- Helen M Bramlett
- The Miami Project to Cure Paralysis/Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida
| | - W Dalton Dietrich
- The Miami Project to Cure Paralysis/Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida
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5
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Cortes DF, Landis MK, Ottens AK. High-capacity peptide-centric platform to decode the proteomic response to brain injury. Electrophoresis 2012; 33:3712-9. [PMID: 23160985 DOI: 10.1002/elps.201200341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 09/12/2012] [Accepted: 09/20/2012] [Indexed: 02/05/2023]
Abstract
Traumatic brain injury (TBI) is a progressive disease process underlain by dynamic and interactive biochemical mechanisms; thus, large-scale and unbiased assessments are needed to fully understand its highly complex pathobiology. Here, we report on a new high-capacity label-free proteomic platform to evaluate the post-TBI neuroproteome. Six orthogonal separation stages and data-independent MS were employed, affording reproducible quantitative assessment on 18 651 peptides across biological replicates. From these data 3587 peptides were statistically responsive to TBI of which 18% were post-translationally modified. Results revealed as many as 484 proteins in the post-TBI neuroproteome, which was fully nine times the number determined from our prior study of focal cortical injury. Yet, these data were generated using 25 times less brain tissue per animal relative to former methodology, permitting greater anatomical specificity and proper biological replication for increased statistical power. Exemplified by these data, we discuss benefits of peptide-centric differential analysis to more accurately infer novel biological findings testable in future hypothesis-driven research. The high-capacity label-free proteomic platform is designed for multi-factor studies aimed at expanding our knowledge on the molecular underpinnings of TBI and to develop better diagnostics and therapeutics.
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Affiliation(s)
- Diego F Cortes
- Department of Anatomy & Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
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Ottens AK, Bustamante L, Golden EC, Yao C, Hayes RL, Wang KKW, Tortella FC, Dave JR. Neuroproteomics: a biochemical means to discriminate the extent and modality of brain injury. J Neurotrauma 2010; 27:1837-52. [PMID: 20698760 DOI: 10.1089/neu.2010.1374] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Diagnosis and treatment of stroke and traumatic brain injury remain significant health care challenges to society. Patient care stands to benefit from an improved understanding of the interactive biochemistry underlying neurotrauma pathobiology. In this study, we assessed the power of neuroproteomics to contrast biochemical responses following ischemic and traumatic brain injuries in the rat. A middle cerebral artery occlusion (MCAO) model was employed in groups of 30-min and 2-h focal neocortical ischemia with reperfusion. Neuroproteomes were assessed via tandem cation-anion exchange chromatography-gel electrophoresis, followed by reversed-phase liquid chromatography-tandem mass spectrometry. MCAO results were compared with those from a previous study of focal contusional brain injury employing the same methodology to characterize homologous neocortical tissues at 2 days post-injury. The 30-min MCAO neuroproteome depicted abridged energy production involving pentose phosphate, modulated synaptic function and plasticity, and increased chaperone activity and cell survival factors. The 2-h MCAO data indicated near complete loss of ATP production, synaptic dysfunction with degraded cytoarchitecture, more conservative chaperone activity, and additional cell survival factors than those seen in the 30-min MCAO model. The TBI group exhibited disrupted metabolism, but with retained malate shuttle functionality. Synaptic dysfunction and cytoarchitectural degradation resembled the 2-h MCAO group; however, chaperone and cell survival factors were more depressed following TBI. These results underscore the utility of neuroproteomics for characterizing interactive biochemistry for profiling and contrasting the molecular aspects underlying the pathobiological differences between types of brain injuries.
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Affiliation(s)
- Andrew K Ottens
- Department of Anatomy, Medical College of Virginia at Virginia Commonwealth University, Richmond, Virginia 23298-0709, USA.
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7
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Brophy GM, Pineda JA, Papa L, Lewis SB, Valadka AB, Hannay HJ, Heaton SC, Demery JA, Liu MC, Tepas JJ, Gabrielli A, Robicsek S, Wang KKW, Robertson CS, Hayes RL. alphaII-Spectrin breakdown product cerebrospinal fluid exposure metrics suggest differences in cellular injury mechanisms after severe traumatic brain injury. J Neurotrauma 2009; 26:471-9. [PMID: 19206997 PMCID: PMC2848834 DOI: 10.1089/neu.2008.0657] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) produces alphaII-spectrin breakdown products (SBDPs) that are potential biomarkers for TBI. To further understand these biomarkers, the present study examined (1) the exposure and kinetic characteristics of SBDPs in cerebrospinal fluid (CSF) of adults with severe TBI, and (2) the relationship between these exposure and kinetic metrics and severity of injury. This clinical database study analyzed CSF concentrations of 150-, 145-, and 120-kDa SBDPs in 38 severe TBI patients. Area under the curve (AUC), mean residence time (MRT), maximum concentration (C(max)), time to maximum concentration (T(max)), and half-life (t(1/2)) were determined for each SBDP. Markers of calpain proteolysis (SBDP150 and SBDP145) had a greater median AUC and C(max) and a shorter MRT than SBDP120, produced by caspase-3 proteolysis in the CSF in TBI patients ( p < 0.001). AUC and MRT for SBDP150 and SBDP15 were significantly greater in patients with worse Glasgow Coma Scale (GCS) scores at 24 h after injury compared to those whose GCS scores improved (AUC p=0.013, MRT p=0.001; AUC p=0.009, MRT p=0.021, respectively). A positive correlation was found between patients with longer elevations in intracranial pressure (ICP) measurements of 25mmHg or higher and those with a greater AUC and MRT for all three biomarkers. This is the first study to show that the biomarkers of proteolysis differentially associated with calpain and caspase-3 activity have distinct CSF exposure profiles following TBI that suggest a prominent role for calpain activity. Further studies are being conducted to determine if exposure and kinetic metrics for biofluid-based biomarkers can predict clinical outcome.
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Affiliation(s)
- Gretchen M Brophy
- Departments of Pharmacy and Neurosurgery, Virginia Commonwealth University, Medical College of Virginia Campus, Richmond, Virginia 23298-0533, USA.
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8
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Oli MW, Hayes RL, Robinson G, Wang KKW. Traumatic brain injury biomarkers: from pipeline to diagnostic assay development. Methods Mol Biol 2009; 566:293-302. [PMID: 20058179 DOI: 10.1007/978-1-59745-562-6_19] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In recent years, the term proteomics is often mentioned together with biomarker discovery, as proteomic studies have the capability of identifying unique and unobvious protein biomarkers from tissues or biofluids derived from animal models or human clinical samples inflicted with various diseases. Proteomics has yielded hundreds of potential biomarker candidates. However, biomarker discovery is only the beginning of a long road for generating a validated, clinically relevant, and FDA-approved biomarker assay. Many technical, financial, legal, and regulatory hurdles have to be overcome before the components can be commercially produced (1, 2). This chapter outlines in a condensed version the steps to successfully develop clinically acceptable biomarkers, given the marker of choice withstands the rigor of developmental challenges along the road.
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Affiliation(s)
- Monika W Oli
- Research and Development Department, Banyan Biomarkers Inc., Alachua, FL, USA.
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9
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Camenisch U, Nägeli H. XPA gene, its product and biological roles. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 637:28-38. [PMID: 19181108 DOI: 10.1007/978-0-387-09599-8_4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 31 kDa XPA protein is part of the core incision complex of the mammalian nucleotide excision repair (NER) system and interacts with DNA as well as with many other NER subunits. In the absence of XPA, no incision complex can form and no excision of damaged DNA damage occurs. A comparative analysis of the DNA-binding properties in the presence of different substrate conformations indicated that XPA protein interacts preferentially with kinked DNA backbones. The DNA-binding domain of XPA protein displays a positively charged deft that is involved in an indirect readout mechanism, presumably by detecting the increased negative potential encountered at sharp DNA bends. We propose that this indirect recognition function contributes to damage verification by probing the susceptibility of the DNA substrate to be kinked during the assembly of NER complexes.
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Affiliation(s)
- Ulrike Camenisch
- Institute of Pharmacology and Toxicology, University of Zürich-Vetsuisse, Zürich, Switzerland.
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10
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Ottens AK, Golden EC, Bustamante L, Hayes RL, Denslow ND, Wang KKW. Proteolysis of multiple myelin basic protein isoforms after neurotrauma: characterization by mass spectrometry. J Neurochem 2007; 104:1404-14. [PMID: 18036155 DOI: 10.1111/j.1471-4159.2007.05086.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neurotrauma, as in the case of traumatic brain injury, promotes protease over-activation characterized by the select fragmentation of brain proteins. The resulting polypeptides are indicators of biochemical processes, which can be used to study post-injury dynamics and may also be developed into biomarkers. To this end, we devised a novel mass spectrometry approach to characterize post-injury calpain proteolytic processing of myelin basic protein (MBP), a biomarker of brain injury that denotes white matter damage and recovery. Our approach exceeds conventional immunological assays in its deconvolution of multiple protein isoforms, its absolute quantification of proteolytic fragments and its polypeptide selectivity. We quantified and characterized post-injury proteolytic processing of all MBP isoforms identified in adult rat cortex. Further, the translation of calpain-cleaved MBP into CSF was verified following brain injury. We ascertained that the exon-6 sequence of MBP resulted in a characteristic shift in gel migration for intact and fragmented protein alike. We also found evidence for a second post-TBI cleavage event within exon-2 and for the dimerization of the post-TBI 4.3 kDa fragment. Ultimately, the novel methodology described here can be used to study MBP dynamics and other similar proteolytic events of relevance to brain injury and other CNS processes.
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Affiliation(s)
- Andrew K Ottens
- Department of Psychiatry, Centers for Neuroproteomics and Biomarker Research and Traumatic Brain Injury Studies at the McKnight Brain Institute of the University of Florida, Gainesville, Florida 32610-0256, USA.
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11
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Falkner KC, Prough RA. Regulation of the rat glutathione S-transferase A2 gene by glucocorticoids: crosstalk through C/EBPs. Drug Metab Rev 2007; 39:401-18. [PMID: 17786629 PMCID: PMC2423428 DOI: 10.1080/03602530701511216] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Regulation of the rat glutathione S-transferase A2 (GSTA2) gene by glucocorticoids is biphasic in its concentration dependence to glucocorticoids, with concentrations of 10-100 nM repressing gene activity (GR-dependent), and concentrations above 1 microM increasing transactivation (PXR-dependent) in adult rat hepatocytes or transient transfection assays. Over-expression of either C/EBP alpha or beta negatively regulates basal and inducible expression of a 1.65 Kb GSTA2 luciferase reporter, and synergizes the response to glucocorticoids (GC). C/EBP responsive elements have been identified in the GSTA2 5'-flanking sequence, associated with the palindrominic Glucocorticoid Responsive Element (GRE), the Ah receptor response elements, and the antioxidant response element. In reporters lacking the palindromic GRE, negative regulation by GC is observed only when C/EBP alpha is co-expressed. Co-transfection of C/EBP alpha/beta induced gene expression of the GSTA2 XRE reporter, but negatively regulated the GSTA2 ARE-reporter. In contrast, the ARE from the rat NAD(P)H quinone oxidoreductase gene was induced by co-transfection of C/EBPs, but was still negatively regulated by GC. PXR-induction of the GSTA2 reporter was partially ablated by co-transfection of C/EBP alpha and enhanced by co-transfection of C/EBPbeta. We conclude that C/EBP alpha and beta are involved in GC-dependent repression of GSTA2 gene expression and ARE sequences that bind C/EBPs appears to be critical for these responses.
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Affiliation(s)
- K Cameron Falkner
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA
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Evans JS, Turner MD. Emerging functions of the calpain superfamily of cysteine proteases in neuroendocrine secretory pathways. J Neurochem 2007; 103:849-59. [PMID: 17666040 DOI: 10.1111/j.1471-4159.2007.04815.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The first calpain protease was discovered over 40 years ago now, yet despite the vast amount of literature that has subsequently emerged detailing their involvement in the pathophysiology of a variety of human diseases, it is only in the last decade that calpain-mediated actions along the secretory pathway have begun to emerge. However, the number of secretory pathway substrates identified and their diversity of function continues to grow. This review summarizes our current knowledge of calpain-mediated mechanisms of action that are pertinent to synaptic vesicle assembly and budding, cytoskeletal organization, endosomal recycling, and exocytotic membrane fusion.
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Affiliation(s)
- Joanne S Evans
- Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, London, UK
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Chen Q, Wang S, Thompson SN, Hall ED, Guttmann RP. Identification and characterization of PEBP as a calpain substrate. J Neurochem 2006; 99:1133-41. [PMID: 17018026 DOI: 10.1111/j.1471-4159.2006.04160.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Calpains are calcium- and thiol-dependent proteases whose dysregulation has been implicated in a number of diseases and conditions such as cardiovascular dysfunction, ischemic stroke, and Alzheimer's disease (AD). While the effects of calpain activity are evident, the precise mechanism(s) by which dysregulated calpain activity results in cellular degeneration are less clear. In order to determine the impact of calpain activity, there is a need to identify the range of specific calpain substrates. Using an in vitro proteomics approach we confirmed that phosphatidylethanolamine-binding protein (PEBP) as a novel in vitro and in situ calpain substrate. We also observed PEBP proteolysis in a model of brain injury in which calpain is clearly activated. In addition, with evidence of calpain dysregulation in AD, we quantitated protein levels of PEBP in postmortem brain samples from the hippocampus of AD and age-matched controls and found that PEBP levels were approximately 20% greater in AD. Finally, with previous evidence that PEBP may act as a serine protease inhibitor, we tested PEBP as an inhibitor of the proteasome and found that PEBP inhibited the chymostrypsin-like activity of the proteasome by approximately 30%. Together these data identify PEBP as a potential in vivo calpain substrate and indicate that increased PEBP levels may contribute to impaired proteasome function.
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Affiliation(s)
- Qinghua Chen
- Department of Gerontology, University of Kentucky, Lexington, Kentucky 40536, USA
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