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Sun MK, Alkon DL. Alzheimer's therapeutic development: shifting neurodegeneration to neuroregeneration. Trends Pharmacol Sci 2024; 45:197-209. [PMID: 38360510 PMCID: PMC10939773 DOI: 10.1016/j.tips.2024.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/13/2024] [Accepted: 01/22/2024] [Indexed: 02/17/2024]
Abstract
Alzheimer's disease (AD), similar to AD-related dementias, is characterized by impaired/lost neuronal structures and functions due to a long progression of neurodegeneration. Derailed endogenous signal pathways and disease processes have critical roles in neurodegeneration and are pharmacological targets in inducing neuroregeneration. Pharmacologically switching/shifting the brain status from neurodegeneration to neuroregeneration is emerging as a new therapeutic concept, one that is not only achievable, but also essential for effective therapy for AD. The results of the pharmacological-induced shift from neurodegeneration to neuroregeneration are twofold: arresting cognitive deterioration (and directing the brain toward cognitive recovery) in established AD, and preventing neurodegeneration through building up cognitive resilience in patients with preclinical or probable AD. In this review, we discuss these new developments in AD pharmacology and relevant clinical trials.
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Affiliation(s)
- Miao-Kun Sun
- Synaptogenix, Inc., 1185 Avenue of the Americas, 3rd Floor, New York, NY 10036, USA.
| | - Daniel L Alkon
- Synaptogenix, Inc., 1185 Avenue of the Americas, 3rd Floor, New York, NY 10036, USA
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2
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La Cognata V, D’Amico AG, Maugeri G, Morello G, Guarnaccia M, Magrì B, Aronica E, Alkon DL, D’Agata V, Cavallaro S. The ε-Isozyme of Protein Kinase C (PKCε) Is Impaired in ALS Motor Cortex and Its Pulse Activation by Bryostatin-1 Produces Long Term Survival in Degenerating SOD1-G93A Motor Neuron-like Cells. Int J Mol Sci 2023; 24:12825. [PMID: 37629005 PMCID: PMC10454105 DOI: 10.3390/ijms241612825] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and ultimately fatal neurodegenerative disease, characterized by a progressive depletion of upper and lower motor neurons (MNs) in the brain and spinal cord. The aberrant regulation of several PKC-mediated signal transduction pathways in ALS has been characterized so far, describing either impaired expression or altered activity of single PKC isozymes (α, β, ζ and δ). Here, we detailed the distribution and cellular localization of the ε-isozyme of protein kinase C (PKCε) in human postmortem motor cortex specimens and reported a significant decrease in both PKCε mRNA (PRKCE) and protein immunoreactivity in a subset of sporadic ALS patients. We furthermore investigated the steady-state levels of both pan and phosphorylated PKCε in doxycycline-activated NSC-34 cell lines carrying the human wild-type (WT) or mutant G93A SOD1 and the biological long-term effect of its transient agonism by Bryostatin-1. The G93A-SOD1 cells showed a significant reduction of the phosphoPKCε/panPKCε ratio compared to the WT. Moreover, a brief pulse activation of PKCε by Bryostatin-1 produced long-term survival in activated G93A-SOD1 degenerating cells in two different cell death paradigms (serum starvation and chemokines-induced toxicity). Altogether, the data support the implication of PKCε in ALS pathophysiology and suggests its pharmacological modulation as a potential neuroprotective strategy, at least in a subgroup of sporadic ALS patients.
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Affiliation(s)
- Valentina La Cognata
- Institute for Biomedical Research and Innovation, National Research Council, 95126 Catania, Italy
| | - Agata Grazia D’Amico
- Section of Human Anatomy and Histology, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Grazia Maugeri
- Section of Human Anatomy and Histology, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Giovanna Morello
- Institute for Biomedical Research and Innovation, National Research Council, 95126 Catania, Italy
| | - Maria Guarnaccia
- Institute for Biomedical Research and Innovation, National Research Council, 95126 Catania, Italy
| | - Benedetta Magrì
- Section of Human Anatomy and Histology, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Eleonora Aronica
- Department of (Neuro) Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam Neuroscience, Meibergdreef 9, 1105 Amsterdam, The Netherlands
| | | | - Velia D’Agata
- Section of Human Anatomy and Histology, Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Sebastiano Cavallaro
- Institute for Biomedical Research and Innovation, National Research Council, 95126 Catania, Italy
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Alkon DL, Sun MK, Tuchman AJ, Thompson RE. Advanced Alzheimer's Disease Patients Show Safe, Significant, and Persistent Benefit in 6-Month Bryostatin Trial. J Alzheimers Dis 2023; 96:759-766. [PMID: 37742657 PMCID: PMC10657679 DOI: 10.3233/jad-230868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2023] [Indexed: 09/26/2023]
Abstract
BACKGROUND In pre-clinical studies, Bryostatin, MW (molecular weight) 904, has demonstrated synaptogenic, anti-apoptotic, anti-amyloid, and anti-tau tangle efficacies. OBJECTIVE To identify AD patients who show significant cognitive benefit versus placebo when treated in a trial with chronic Bryostatin dosing. METHODS In this 6-month 122 AD patient Bryostatin trial, there were two cohorts: the Moderate Cohort (MMSE, Mini-Mental Status Exam: 15-18) and the Moderately Severe Cohort (MMSE 10-14) as pre-specified secondary endpoints. Patient randomization was stratified by baseline SIB to insure balance in baseline cognitive ability between treatment arms. RESULTS With no safety events noted by the data safety and monitoring board, the Moderately Severe (MMSE 10-14) Bryostatin-treated patients were significantly improved above the placebo patients for Weeks #13 through Week #42. After two cycles of 7 x i.v. Bryostatin doses over a 26-week period, the 10-14 Cohort Severe Impairment Battery (SIB), measured every 2 weeks, showed significant benefit using a Mixed Model Repeated Measures model (MMRM, 2-tailed, p < 0.05) for Weeks #13 through #42, even 16 weeks after dosing completion by Week #26. Placebo 10-14 patients showed no benefit, declining to negative 12.8 points by Week #42. Trend analyses confirmed the MMRM data for this Cohort, with a significant downward slope (equivalent to Cognitive Decline) for the placebo group, p < 0.001, 2-tailed, but no significant decline for the Bryostatin-treated group (p = 0.409, NS), treatment versus placebo p < 0.007. The Moderate Cohort patients showed no significant benefit. CONCLUSIONS The Bryostatin-treated MMSE 10-14 patients showed no significant cognitive decline throughout the 10-month trial, versus placebo patients' decline of -12.8 SIB points.
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Affiliation(s)
| | | | - Alan J. Tuchman
- Synaptogenix, Inc., New York, NY, USA
- New York Medical College, Valhalla, NY, USA
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Thompson RE, Tuchman AJ, Alkon DL. Bryostatin Placebo-Controlled Trials Indicate Cognitive Restoration Above Baseline for Advanced Alzheimer’s Disease in the Absence of Memantine1. J Alzheimers Dis 2022; 86:1221-1229. [PMID: 35124654 PMCID: PMC9108553 DOI: 10.3233/jad-215545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Background: In pre-clinical studies of Alzheimer’s disease (AD) transgenic mice, bryostatin restored synaptic connections, prevented neuronal death, reduced amyloid plaques, and reduced neurofibrillary tangles. Objective: Within pre-specified cohorts of advanced AD patients in two double-blind placebo-controlled bryostatin Phase II trials, to conduct exploratory statistical analyses of patients with identical conditions of enrollment and treatment. Methods: Severe Impairment Battery (SIB) scores above baseline at 5, 9, and 13 weeks were analyzed initially in the complete cases, with multiple imputation methods based on an iterative Markov chain Monte Carlo algorithm used for missing SIB scores. To mitigate confounding by a chance imbalance of 4.9 SIB baseline scores (Study #203), each patient was used as their own control with differences in 13-week SIB from baseline in single trial and pooled analyses to measure benefit at 13 weeks using general estimating equations (GEE) modeling. Results: Patients treated with bryostatin pre-specified at Mini-Mental State Examination scores 10–14, without memantine, showed baseline balance, complete safety, and SIB improvements at 13 weeks with multiple imputation analysis: Study #203 = 4.1 SIB points above baseline (p = 0.005), and Study #202 = 4.2 SIB points above baseline (p = 0.016). An increased power (N = 95) “pooled analysis” showed an increased SIB over time and a higher mean SIB at 13 weeks in the bryostatin treatment group (p < 0.001) but not significant (NS) for the placebo patients. Conclusion: Pre-specified exploratory analyses for the individual trials and the pooled trials confirmed significant bryostatin-induced improvement over baseline (treatment p < 0.001, placebo NS).
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Affiliation(s)
| | - Alan J. Tuchman
- New York Medical College, Valhalla, NY, USA
- Synaptogenix, Inc., New York, NY, USA
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Cogram P, Alkon DL, Crockford D, Deacon RMJ, Hurley MJ, Altimiras F, Sun MK, Tranfaglia M. Chronic bryostatin-1 rescues autistic and cognitive phenotypes in the fragile X mice. Sci Rep 2020; 10:18058. [PMID: 33093534 PMCID: PMC7581799 DOI: 10.1038/s41598-020-74848-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 10/05/2020] [Indexed: 12/20/2022] Open
Abstract
Fragile X syndrome (FXS), an X-chromosome linked intellectual disability, is the leading monogenetic cause of autism spectrum disorder (ASD), a neurodevelopmental condition that currently has no specific drug treatment. Building upon the demonstrated therapeutic effects on spatial memory of bryostatin-1, a relatively specific activator of protein kinase C (PKC)ε, (also of PKCα) on impaired synaptic plasticity/maturation and spatial learning and memory in FXS mice, we investigated whether bryostatin-1 might affect the autistic phenotypes and other behaviors, including open field activity, activities of daily living (nesting and marble burying), at the effective therapeutic dose for spatial memory deficits. Further evaluation included other non-spatial learning and memory tasks. Interestingly, a short period of treatment (5 weeks) only produced very limited or no therapeutic effects on the autistic and cognitive phenotypes in the Fmr1 KO2 mice, while a longer treatment (13 weeks) with the same dose of bryostatin-1 effectively rescued the autistic and non-spatial learning deficit cognitive phenotypes. It is possible that longer-term treatment would result in further improvement in these fragile X phenotypes. This effect is clearly different from other treatment strategies tested to date, in that the drug shows little acute effect, but strong long-term effects. It also shows no evidence of tolerance, which has been a problem with other drug classes (mGluR5 antagonists, GABA-A and -B agonists). The results strongly suggest that, at appropriate dosing and therapeutic period, chronic bryostatin-1 may have great therapeutic value for both ASD and FXS.
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Affiliation(s)
- Patricia Cogram
- FRAXA-DVI, FRAXA, Santiago, Chile. .,IEB, Faculty of Science, University of Chile, Santiago, Chile.
| | | | | | - Robert M J Deacon
- FRAXA-DVI, FRAXA, Santiago, Chile.,IEB, Faculty of Science, University of Chile, Santiago, Chile
| | - Michael J Hurley
- Neuroimmunology, Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK
| | - Francisco Altimiras
- Faculty of Engineering, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.,Faculty of Engineering and Business, Universidad de las Américas, Santiago, Chile
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Alkon DL, Thompson R, Wei LJ, Tuchman A. P4-661: REPLICATION TRIAL TO CONFIRM REVERSAL OF COGNITIVE DECLINE WITH BRYOSTATIN FOR ADVANCED ALZHEIMER'S PATIENTS IN THE ABSENCE OF MEMANTINE. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.09.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Farlow MR, Thompson RE, Wei LJ, Tuchman AJ, Grenier E, Crockford D, Wilke S, Benison J, Alkon DL. A Randomized, Double-Blind, Placebo-Controlled, Phase II Study Assessing Safety, Tolerability, and Efficacy of Bryostatin in the Treatment of Moderately Severe to Severe Alzheimer's Disease. J Alzheimers Dis 2019; 67:555-570. [PMID: 30530975 PMCID: PMC6398557 DOI: 10.3233/jad-180759] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2018] [Indexed: 01/17/2023]
Abstract
BACKGROUND Bryostatin-activated PKC epsilon pre-clinically induces synaptogenesis, anti-apoptosis, anti-amyloid-β oligomers, and anti-hyperphosphorylated tau. OBJECTIVES To investigate bryostatin safety, tolerability, and efficacy to improve cognition in advanced Alzheimer's disease (AD) patients. METHODS A double-blind, randomized, placebo-controlled Phase II, 12-week trial of i.v. bryostatin for 150 advanced AD patients (55-85) with MMSE-2 of 4-15, randomized 1:1:1 into 20 μg and 40 μg bryostatin, and placebo arms. The Full Analysis Set (FAS) and the Completer Analysis Set (CAS) were pre-specified alternative assessments (1-sided, p < 0.1 for primary efficacy, and 2-sided, p < 0.05 for pre-specified and post hoc exploratory analyses). RESULTS The safety profile was similar for 20 μg treatment and placebo patients. The 40 μg patients showed safety and drop-out issues, but no efficacy. Primary improvement of Severe Impairment Battery (SIB) scores at 13 weeks was not significant (p = 0.134) in the FAS, although in the CAS, the SIB comparison favored 20 μg bryostatin compared to placebo patients (p < 0.07). Secondary analyses at weeks 5 and 15 (i.e., 30 days post-final dosing) also favored 20 μg bryostatin compared to placebo patients. A pre-specified ANCOVA for baseline memantine blocking bryostatin and positive post-hoc trend analyses were statistically significant (2-sided, p < 0.05). CONCLUSION Although the primary endpoint was not significant in the FAS, primary and secondary analyses in the CAS, and pre-specified and post-hoc exploratory analyses did favor bryostatin 20 μg compared to the placebo cohort. These promising Phase II results support further trials of 20 μg bryostatin- without memantine- to treat AD.
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Nelson TJ, Sun MK, Lim C, Sen A, Khan T, Chirila FV, Alkon DL. Bryostatin Effects on Cognitive Function and PKCɛ in Alzheimer's Disease Phase IIa and Expanded Access Trials. J Alzheimers Dis 2018; 58:521-535. [PMID: 28482641 PMCID: PMC5438479 DOI: 10.3233/jad-170161] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Bryostatin 1, a potent activator of protein kinase C epsilon (PKCɛ), has been shown to reverse synaptic loss and facilitate synaptic maturation in animal models of Alzheimer’s disease (AD), Fragile X, stroke, and other neurological disorders. In a single-dose (25 μg/m2) randomized double-blind Phase IIa clinical trial, bryostatin levels reached a maximum at 1-2 h after the start of infusion. In close parallel with peak blood levels of bryostatin, an increase of PBMC PKCɛ was measured (p = 0.0185) within 1 h from the onset of infusion. Of 9 patients with a clinical diagnosis of AD, of which 6 received drug and 3 received vehicle within a double-blind protocol, bryostatin increased the Mini-Mental State Examination (MMSE) score by +1.83±0.70 unit at 3 h versus –1.00±1.53 unit for placebo. Bryostatin was well tolerated in these AD patients and no drug-related adverse events were reported. The 25 μg/m2 administered dose was based on prior clinical experience with three Expanded Access advanced AD patients treated with bryostatin, in which return of major functions such as swallowing, vocalization, and word recognition were noted. In one Expanded Access patient trial, elevated PKCɛ levels closely tracked cognitive benefits in the first 24 weeks as measured by MMSE and ADCS-ADL psychometrics. Pre-clinical mouse studies showed effective activation of PKCɛ and increased levels of BDNF and PSD-95. Together, these Phase IIa, Expanded Access, and pre-clinical results provide initial encouragement for bryostatin 1 as a potential treatment for AD.
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Affiliation(s)
- Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,West Virginia University, Morgantown, WV, USA
| | - Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,West Virginia University, Morgantown, WV, USA
| | - Chol Lim
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,West Virginia University, Morgantown, WV, USA
| | - Abhik Sen
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,West Virginia University, Morgantown, WV, USA
| | - Tapan Khan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,West Virginia University, Morgantown, WV, USA
| | - Florin V Chirila
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,Neurodiagnostics, LLC, Rockville, MD, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.,Neurotrope Biosciences, LLC, New York, NY, USA
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Sen A, Nelson TJ, Alkon DL, Hongpaisan J. Loss in PKC Epsilon Causes Downregulation of MnSOD and BDNF Expression in Neurons of Alzheimer's Disease Hippocampus. J Alzheimers Dis 2018; 63:1173-1189. [PMID: 29710707 DOI: 10.3233/jad-171008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Oxidative stress and amyloid-β (Aβ) oligomers have been implicated in Alzheimer's disease (AD). The growth and maintenance of neuronal networks are influenced by brain derived neurotrophic factor (BDNF) expression, which is promoted by protein kinase C epsilon (PKCɛ). We investigated the reciprocal interaction among oxidative stress, Aβ, and PKCɛ levels and subsequent PKCɛ-dependent MnSOD and BDNF expression in hippocampal pyramidal neurons. Reduced levels of PKCɛ, MnSOD, and BDNF and an increased level of Aβ were also found in hippocampal neurons from autopsy-confirmed AD patients. In cultured human primary hippocampal neurons, spherical aggregation of Aβ (amylospheroids) decreased PKCɛ and MnSOD. Treatment with t-butyl hydroperoxide (TBHP) increased superoxide, the oxidative DNA/RNA damage marker, 8-OHG, and Aβ levels, but reduced PKCɛ, MnSOD, BDNF, and cultured neuron density. These changes were reversed with the PKCɛ activators, bryostatin and DCPLA-ME. PKCɛ knockdown suppressed PKCɛ, MnSOD, and BDNF but increased Aβ. In cultured neurons, the increase in reactive oxygen species (ROS) associated with reduced PKCɛ during neurodegeneration was inhibited by the SOD mimetic MnTMPyP and the ROS scavenger NAc, indicating that strong oxidative stress suppresses PKCɛ level. Reduction of PKCɛ and MnSOD was prevented with the PKCɛ activator bryostatin in 5-6-month-old Tg2576 AD transgenic mice. In conclusion, oxidative stress and Aβ decrease PKCɛ expression. Reciprocally, a depression of PKCɛ reduces BDNF and MnSOD, resulting in oxidative stress. These changes can be prevented with the PKCɛ-specific activators.
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Affiliation(s)
- Abhik Sen
- Center for Neurodegenerative Diseases, Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV, USA
| | - Thomas J Nelson
- Center for Neurodegenerative Diseases, Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV, USA
| | | | - Jarin Hongpaisan
- Center for Neurodegenerative Diseases, Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV, USA
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Khan TK, Wender PA, Alkon DL. Bryostatin and its synthetic analog, picolog rescue dermal fibroblasts from prolonged stress and contribute to survival and rejuvenation of human skin equivalents. J Cell Physiol 2017; 233:1523-1534. [PMID: 28590053 DOI: 10.1002/jcp.26043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 06/06/2017] [Indexed: 11/09/2022]
Abstract
Skin health is associated with the day-to-day activity of fibroblasts. The primary function of fibroblasts is to synthesize structural proteins, such as collagen, extracellular matrix proteins, and other proteins that support the structural integrity of the skin and are associated with younger, firmer, and more elastic skin that is better able to resist and recover from injury. At sub-nanomolar concentrations (0.03-0.3 nM), bryostatin-1 and its synthetic analog, picolog (0.1-10 nM) sustained the survival and activation of human dermal fibroblasts cultured under the stressful condition of prolonged serum deprivation. Bryostatin-1 treatment stabilized human skin equivalents (HSEs), a bioengineered combination of primary human skin cells (keratinocytes and dermal fibroblasts) on an extracellular matrix composed of mainly collagen. Fibroblasts activated by bryostatin-1 protected the structural integrity of HSEs. Bryostatin-1 and picolog prolonged activation of Erk in fibroblasts to promote cell survival. Chronic stress promotes the progression of apoptosis. Dermal fibroblasts constitutively express all components of Fas associated apoptosis, including caspase-8, an initiator enzyme of apoptosis. Prolong bryostatin-1 treatment reduced apoptosis by decreasing caspase-8 and protected dermal fibroblasts. Our data suggest that bryostatin-1 and picolog could be useful in anti-aging skincare, and could have applications in tissue engineering and regenerative medicine.
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Affiliation(s)
- Tapan K Khan
- Center for Neurodegenerative Diseases, Blanchette Rockefeller Neurosciences Institute at West Virginia University, Morgantown, West Virginia
| | - Paul A Wender
- Department of Chemistry, Stanford University, Stanford, California.,Department of Chemical and Systems Biology, Stanford University, Stanford, California
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Alkon DL, Hongpaisan J, Sun MK. Effects of chronic bryostatin-1 on treatment-resistant depression in rats. Eur J Pharmacol 2017; 807:71-74. [DOI: 10.1016/j.ejphar.2017.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/11/2017] [Accepted: 05/01/2017] [Indexed: 01/05/2023]
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Abstract
Apolipoprotein E4 (ApoE4) is a major genetic risk factor for sporadic or late onset Alzheimer’s disease (AD). Brain-derived neurotrophic factor (BDNF) is decreased by 3 to 4-fold in the brains of AD patients at autopsy. ApoE4 mice also have reduced BDNF levels. However, there have been no reports relating the different ApoE isoforms or AD to differential regulation of BDNF. Here we report that in the hippocampal regions of AD patients both prepro-BDNF and pro-BDNF expression showed a 40 and 60% decrease respectively compared to that expression in the hippocampi of age-matched control patients. We further report that ApoE isoforms differentially regulate maturation and secretion of BDNF from primary human astrocytes. After 24 h, ApoE3 treated astrocytes secreted 1.75- fold higher pro-BDNF than ApoE2-treated astrocytes, and ApoE2-treated astrocytes secreted 3-fold more mature-BDNF (m-BDNF) than ApoE3-treated astrocytes. In contrast, ApoE4-treated cells secreted negligible amounts of m-BDNF or pro-BDNF. ApoE2 increased the level of intracellular pre-pro BDNF by 19.04 ± 6.68%, while ApoE4 reduced the pre-pro BDNF by 21.61 ± 5.9% compared to untreated cells. Similar results were also seen in ApoE2, ApoE3 or ApoE4 treated cells at 4 h. Together, these results indicate that an ApoE2 or ApoE3 mediated positive regulation of BDNF may be protective while ApoE4 related defects in BDNF processing could lead to AD pathophysiology. These interactions of the ApoE isoforms with BDNF may help explain the increased risk of AD associated with the ApoE4 isoform.
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Affiliation(s)
- Abhik Sen
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV, 26505, USA.
| | - Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV, 26505, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV, 26505, USA
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Lim CS, Alkon DL. Inhibition of coactivator-associated arginine methyltransferase 1 modulates dendritic arborization and spine maturation of cultured hippocampal neurons. J Biol Chem 2017; 292:6402-6413. [PMID: 28264928 DOI: 10.1074/jbc.m117.775619] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 02/24/2017] [Indexed: 01/11/2023] Open
Abstract
An improved understanding of the molecular mechanisms in synapse formation provides insight into both learning and memory and the etiology of neurodegenerative disorders. Coactivator-associated arginine methyltransferase 1 (CARM1) is a protein methyltransferase that negatively regulates synaptic gene expression and inhibits neuronal differentiation. Despite its regulatory function in neurons, little is known about the CARM1 cellular location and its role in dendritic maturation and synapse formation. Here, we examined the effects of CARM1 inhibition on dendritic spine and synapse morphology in the rat hippocampus. CARM1 was localized in hippocampal post-synapses, with immunocytochemistry and electron microscopy revealing co-localization of CARM1 with post-synaptic density (PSD)-95 protein, a post-synaptic marker. Specific siRNA-mediated suppression of CARM1 expression resulted in precocious dendritic maturation, with increased spine width and density at sites along dendrites and induction of mushroom-type spines. These changes were accompanied by a striking increase in the cluster size and number of key synaptic proteins, including N-methyl-d-aspartate receptor subunit 2B (NR2B) and PSD-95. Similarly, pharmacological inhibition of CARM1 activity with the CARM1-specific inhibitor AMI-1 significantly increased spine width and mushroom-type spines and also increased the cluster size and number of NR2B and cluster size of PSD-95. These results suggest that CARM1 is a post-synaptic protein that plays roles in dendritic maturation and synaptic formation and that spatiotemporal regulation of CARM1 activity modulates neuronal connectivity and improves synaptic dysfunction.
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Affiliation(s)
- Chol Seung Lim
- From the Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, West Virginia 26505
| | - Daniel L Alkon
- From the Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, West Virginia 26505
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Denvir J, Neitch S, Fan J, Niles RM, Boskovic G, Schreurs BG, Primerano DA, Alkon DL. Identification of the PS1 Thr147Ile Variant in a Family with Very Early Onset Dementia and Expressive Aphasia. J Alzheimers Dis 2016; 46:483-90. [PMID: 25812849 PMCID: PMC4583332 DOI: 10.3233/jad-150051] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Early onset dementias have variable clinical presentations and are often difficult to diagnose. We established a family pedigree that demonstrated consistent recurrence of very early onset dementia in successive generations. OBJECTIVE AND METHOD In order to refine the diagnosis in this family, we sequenced the exomes of two affected family members and relied on discrete filtering to identify disease genes and the corresponding causal variants. RESULTS Among the 720 nonsynonymous single nucleotide polymorphisms (SNPs) shared by two affected members, we found a C to T transition that gives rise to a Thr147Ile missense substitution in the presenilin 1 (PS1) protein. The presence of this same mutation in a French early-onset Alzheimer's disease family, other affected members of the family, and the predicted high pathogenicity of the substitution strongly suggest that it is the causal variant. In addition to exceptionally young age of onset, we also observed significant limb spasticity and early loss of speech, concurrent with progression of dementia in affected family members. These findings extend the clinical presentation associated with the Thr147Ile variant. Lastly, one member with the Thr147Ile variant was treated with the PKC epsilon activator, bryostatin, in a compassionate use trial after successful FDA review. Initial improvements with this treatment were unexpectedly clear, including return of some speech, increased attentional focus, ability to swallow, and some apparent decrease in limb spasticity. CONCLUSIONS Our findings confirm the role of the PS1 Thr147Ile substitution in Alzheimer's disease and expand the clinical phenotype to include expressive aphasia and very early onset of dementia.
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Affiliation(s)
- James Denvir
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Shirley Neitch
- Department of Internal Medicine, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Jun Fan
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Richard M Niles
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Goran Boskovic
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Bernard G Schreurs
- Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV, USA
| | - Donald A Primerano
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV, USA
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Khan TK, Alkon DL. Alzheimer's Disease Cerebrospinal Fluid and Neuroimaging Biomarkers: Diagnostic Accuracy and Relationship to Drug Efficacy. J Alzheimers Dis 2016; 46:817-36. [PMID: 26402622 DOI: 10.3233/jad-150238] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Widely researched Alzheimer's disease (AD) biomarkers include in vivo brain imaging with PET and MRI, imaging of amyloid plaques, and biochemical assays of Aβ 1 - 42, total tau, and phosphorylated tau (p-tau-181) in cerebrospinal fluid (CSF). In this review, we critically evaluate these biomarkers and discuss their clinical utility for the differential diagnosis of AD. Current AD biomarker tests are either highly invasive (requiring CSF collection) or expensive and labor-intensive (neuroimaging), making them unsuitable for use in the primary care, clinical office-based setting, or to assess drug efficacy in clinical trials. In addition, CSF and neuroimaging biomarkers continue to face challenges in achieving required sensitivity and specificity and minimizing center-to-center variability (for CSF-Aβ 1 - 42 biomarkers CV = 26.5% ; http://www.alzforum.org/news/conference-coverage/paris-standardization-hurdle-spinal-fluid-imaging-markers). Although potentially useful for selecting patient populations for inclusion in AD clinical trials, the utility of CSF biomarkers and neuroimaging techniques as surrogate endpoints of drug efficacy needs to be validated. Recent trials of β- and γ-secretase inhibitors and Aβ immunization-based therapies in AD showed no significant cognitive improvements, despite changes in CSF and neuroimaging biomarkers. As we learn more about the dysfunctional cellular and molecular signaling processes that occur in AD, and how these processes are manifested in tissues outside of the brain, new peripheral biomarkers may also be validated as non-invasive tests to diagnose preclinical and clinical AD.
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16
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Sen A, Hongpaisan J, Wang D, Nelson TJ, Alkon DL. Protein Kinase Cϵ (PKCϵ) Promotes Synaptogenesis through Membrane Accumulation of the Postsynaptic Density Protein PSD-95. J Biol Chem 2016; 291:16462-76. [PMID: 27330081 DOI: 10.1074/jbc.m116.730440] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 11/06/2022] Open
Abstract
Protein kinase Cϵ (PKCϵ) promotes synaptic maturation and synaptogenesis via activation of synaptic growth factors such as BDNF, NGF, and IGF. However, many of the detailed mechanisms by which PKCϵ induces synaptogenesis are not fully understood. Accumulation of PSD-95 to the postsynaptic density (PSD) is known to lead to synaptic maturation and strengthening of excitatory synapses. Here we investigated the relationship between PKCϵ and PSD-95. We show that the PKCϵ activators dicyclopropanated linoleic acid methyl ester and bryostatin 1 induce phosphorylation of PSD-95 at the serine 295 residue, increase the levels of PSD-95, and enhance its membrane localization. Elimination of the serine 295 residue in PSD-95 abolished PKCϵ-induced membrane accumulation. Knockdown of either PKCϵ or JNK1 prevented PKCϵ activator-mediated membrane accumulation of PSD-95. PKCϵ directly phosphorylated PSD-95 and JNK1 in vitro Inhibiting PKCϵ, JNK, or calcium/calmodulin-dependent kinase II activity prevented the effects of PKCϵ activators on PSD-95 phosphorylation. Increase in membrane accumulation of PKCϵ and phosphorylated PSD-95 (p-PSD-95(S295)) coincided with an increased number of synapses and increased amplitudes of excitatory post-synaptic potentials (EPSPs) in adult rat hippocampal slices. Knockdown of PKCϵ also reduced the synthesis of PSD-95 and the presynaptic protein synaptophysin by 30 and 44%, respectively. Prolonged activation of PKCϵ increased synapse number by 2-fold, increased presynaptic vesicle density, and greatly increased PSD-95 clustering. These results indicate that PKCϵ promotes synaptogenesis by activating PSD-95 phosphorylation directly through JNK1 and calcium/calmodulin-dependent kinase II and also by inducing expression of PSD-95 and synaptophysin.
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Affiliation(s)
- Abhik Sen
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Jarin Hongpaisan
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Desheng Wang
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Thomas J Nelson
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Daniel L Alkon
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
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17
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Sun MK, Hongpaisan J, Alkon DL. Rescue of Synaptic Phenotypes and Spatial Memory in Young Fragile X Mice. ACTA ACUST UNITED AC 2016; 357:300-10. [PMID: 26941170 DOI: 10.1124/jpet.115.231100] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/02/2016] [Indexed: 01/01/2023]
Abstract
Fragile X syndrome (FXS) is characterized by synaptic immaturity, cognitive impairment, and behavioral changes. The disorder is caused by transcriptional shutdown in neurons of thefragile X mental retardation 1gene product, fragile X mental retardation protein. Fragile X mental retardation protein is a repressor of dendritic mRNA translation and its silencing leads to dysregulation of synaptically driven protein synthesis and impairments of intellect, cognition, and behavior, and FXS is a disorder that currently has no effective therapeutics. Here, young fragile X mice were treated with chronic bryostatin-1, a relatively selective protein kinase Cεactivator, which induces synaptogenesis and synaptic maturation/repair. Chronic treatment with bryostatin-1 rescues young fragile X mice from the disorder phenotypes, including normalization of most FXS abnormalities in 1) hippocampal brain-derived neurotrophic factor expression, 2) postsynaptic density-95 levels, 3) transformation of immature dendritic spines to mature synapses, 4) densities of the presynaptic and postsynaptic membranes, and 5) spatial learning and memory. The therapeutic effects were achieved without downregulation of metabotropic glutamate receptor (mGluR) 5 in the hippocampus and are more dramatic than those of a late-onset treatment in adult fragile X mice. mGluR5 expression was in fact lower in fragile X mice and its expression was restored with the bryostatin-1 treatment. Our results show that synaptic and cognitive function of young FXS mice can be normalized through pharmacological treatment without downregulation of mGluR5 and that bryostatin-1-like agents may represent a novel class of drugs to treat fragile X mental retardation at a young age and in adults.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia
| | - Jarin Hongpaisan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia
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18
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Lucke-Wold BP, Logsdon AF, Smith KE, Turner RC, Alkon DL, Tan Z, Naser ZJ, Knotts CM, Huber JD, Rosen CL. Bryostatin-1 Restores Blood Brain Barrier Integrity following Blast-Induced Traumatic Brain Injury. Mol Neurobiol 2015; 52:1119-1134. [PMID: 25301233 PMCID: PMC5000781 DOI: 10.1007/s12035-014-8902-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/24/2014] [Indexed: 02/08/2023]
Abstract
Recent wars in Iraq and Afghanistan have accounted for an estimated 270,000 blast exposures among military personnel. Blast traumatic brain injury (TBI) is the 'signature injury' of modern warfare. Blood brain barrier (BBB) disruption following blast TBI can lead to long-term and diffuse neuroinflammation. In this study, we investigate for the first time the role of bryostatin-1, a specific protein kinase C (PKC) modulator, in ameliorating BBB breakdown. Thirty seven Sprague-Dawley rats were used for this study. We utilized a clinically relevant and validated blast model to expose animals to moderate blast exposure. Groups included: control, single blast exposure, and single blast exposure + bryostatin-1. Bryostatin-1 was administered i.p. 2.5 mg/kg after blast exposure. Evan's blue, immunohistochemistry, and western blot analysis were performed to assess injury. Evan's blue binds to albumin and is a marker for BBB disruption. The single blast exposure caused an increase in permeability compared to control (t = 4.808, p < 0.05), and a reduction back toward control levels when bryostatin-1 was administered (t = 5.113, p < 0.01). Three important PKC isozymes, PKCα, PKCδ, and PKCε, were co-localized primarily with endothelial cells but not astrocytes. Bryostatin-1 administration reduced toxic PKCα levels back toward control levels (t = 4.559, p < 0.01) and increased the neuroprotective isozyme PKCε (t = 6.102, p < 0.01). Bryostatin-1 caused a significant increase in the tight junction proteins VE-cadherin, ZO-1, and occludin through modulation of PKC activity. Bryostatin-1 ultimately decreased BBB breakdown potentially due to modulation of PKC isozymes. Future work will examine the role of bryostatin-1 in preventing chronic neurodegeneration following repetitive neurotrauma.
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Affiliation(s)
- Brandon P Lucke-Wold
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Aric F Logsdon
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV, 26506, USA
| | - Kelly E Smith
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV, 26506, USA
| | - Ryan C Turner
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, 26506, USA
| | - Zhenjun Tan
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Zachary J Naser
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Office of Professional Studies in Health Sciences, Drexel University College of Medicine, Philadelphia, PA, 19102, USA
| | - Chelsea M Knotts
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Jason D Huber
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV, 26506, USA
| | - Charles L Rosen
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, 26506, USA.
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, 26506, USA.
- Department of Neurosurgery, West Virginia University School of Medicine, One Medical Center Drive, Suite 4300, Health Sciences Center, PO Box 9183, Morgantown, WV, 26506-9183, USA.
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19
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Abstract
Currently available diagnostic tests have moved the field closer to early diagnosis of Alzheimer's disease (AD); however, a definitive diagnosis is made only with the development of clinical dementia and the presence of amyloid plaques and neurofibrillary tangles at autopsy. An ideal antemortem AD biomarker should satisfy the following criteria: the ability to diagnose AD with high sensitivity and specificity as confirmed by the gold standard of autopsy validation; the ability to detect early-stage disease and track the progression of AD; and monitor therapeutic efficacy. AD biomarker technologies currently under development include in vivo brain imaging with PET and MRI (i.e., imaging of amyloid plaques, biochemical assays in cerebrospinal fluid (CSF) and peripheral tissues. CSF biomarkers have received increased attention in the past decade. However, it is unclear whether these biomarkers are capable of early diagnosis of AD, prior to Aβ accumulation, or whether they can differentiate between AD and non-AD dementias. In addition, CSF biomarkers may not lend themselves to diagnostic screening of elderly patients, given the invasiveness of lumbar puncture, inter-laboratory variability in techniques and sample handling, and the circadian fluctuation of CSF components. Although commonly viewed as an abnormality of the brain, AD is a systemic disease with associated dysfunction in metabolic, oxidative, inflammatory, and biochemical pathways in peripheral tissues, such as the skin and blood cells. This has led researchers to investigate and develop assays of peripheral AD biomarkers (a few with high sensitivity and specificity) that require minimally invasive skin or blood samples.
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Affiliation(s)
- Tapan K Khan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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20
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Tan Z, Lucke-Wold BP, Logsdon AF, Turner RC, Tan C, Li X, Hongpaison J, Alkon DL, Simpkins JW, Rosen CL, Huber JD. Bryostatin extends tPA time window to 6 h following middle cerebral artery occlusion in aged female rats. Eur J Pharmacol 2015; 764:404-412. [PMID: 26189021 PMCID: PMC4698807 DOI: 10.1016/j.ejphar.2015.07.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 07/14/2015] [Accepted: 07/15/2015] [Indexed: 02/08/2023]
Abstract
Blood-brain barrier (BBB) disruption and hemorrhagic transformation (HT) following ischemic/reperfusion injury contributes to post-stroke morbidity and mortality. Bryostatin, a potent protein kinase C (PKC) modulator, has shown promise in treating neurological injury. In the present study, we tested the hypothesis that administration of bryostatin would reduce BBB disruption and HT following acute ischemic stroke; thus, prolonging the time window for administering recombinant tissue plasminogen activator (r-tPA). Acute cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery (MCAO) in 18-20-month-old female rats using an autologous blood clot with delayed r-tPA reperfusion. Bryostatin (or vehicle) was administered at 2 h post-MCAO and r-tPA was administered at 6 h post-MCAO. Functional assessment, lesion volume, and hemispheric swelling measurements were performed at 24 h post-MCAO. Assessment of BBB permeability, measurement of hemoglobin, assessment of matrix metalloproteinase (MMP) levels by gel zymography, and measurement of PKCε, PKCα, PKCδ expression by western blot were conducted at 24 h post-MCAO. Rats treated with bryostatin prior to r-tPA administration had decreased mortality and hemispheric swelling when compared with rats treated with r-tPA alone. Administration of bryostatin also limited BBB disruption and HT and down-regulated MMP-9 expression while up-regulating PKCε expression at 24 h post-MCAO. Bryostatin administration ameliorates BBB disruption and reduces the risk of HT by down-regulating MMP-9 activation and up-regulating PKCε. In this proof-of-concept study, bryostatin treatment lengthened the time-to-treatment window and enhanced the efficacy and safety of thrombolytic therapy.
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Affiliation(s)
- Zhenjun Tan
- Department of Neurosurgery, School of Medicine, United States
| | | | - Aric F Logsdon
- Department of Basic Pharmaceutical Science, School of Pharmacy, United States
| | - Ryan C Turner
- Department of Neurosurgery, School of Medicine, United States
| | - Cong Tan
- Department of Physiology and Pharmacology, School of Medicine, United States
| | - Xinlan Li
- Department of Neurosurgery, School of Medicine, United States
| | - Jarin Hongpaison
- Blanchette Rockfeller Neuroscience Institute, West Virginia University, United States
| | - Daniel L Alkon
- Blanchette Rockfeller Neuroscience Institute, West Virginia University, United States
| | - James W Simpkins
- Department of Physiology and Pharmacology, School of Medicine, United States
| | - Charles L Rosen
- Department of Neurosurgery, School of Medicine, United States
| | - Jason D Huber
- Department of Basic Pharmaceutical Science, School of Pharmacy, United States.
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Abstract
In Alzheimer's disease (AD) transgenic mice, activation of synaptogenic protein kinase C ε (PKCε) was found to prevent synaptotoxic amyloid-β (Aβ)-oligomer elevation, PKCε deficits, early synaptic loss, cognitive deficits, and amyloid plaque formation. In humans, to study the role of PKCε in the pathophysiology of AD and to evaluate its possible use as an early AD-biomarker, we examined PKCε and Aβ in the brains of autopsy-confirmed AD patients (n = 20) and age-matched controls (AC, n = 19), and in skin fibroblast samples from AD (n = 14), non-AD dementia patients (n = 14), and AC (n = 22). Intraneuronal Aβ levels were measured immunohistochemically (using an Aβ-specific antibody) in hippocampal pyramidal cells of human autopsy brains. PKCε was significantly lower in the hippocampus and temporal pole areas of AD brains, whereas Aβ levels were significantly higher. The ratio of PKCε to Aβ in individual CA1 pyramidal cells was markedly lower in the autopsy AD brains versus controls. PKCε was inversely correlated with Aβ levels in controls, whereas in AD patients, PKCε showed no significant correlation with Aβ. In autopsy brains, PKCε decreased as the Braak score increased. Skin fibroblast samples from AD patients also demonstrated a deficit in PKCε compared to controls and an AD-specific change in the Aβ-oligomer effects on PKCε. Together, these data demonstrate that the relationship between Aβ levels and PKCε is markedly altered in AD patients' brains and skin fibroblasts, reflecting a loss of protective effect of PKCε against toxic Aβ accumulation. These changes of PKCε levels in human skin fibroblasts may provide an accurate, non-invasive peripheral AD biomarker.
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Affiliation(s)
- Tapan K Khan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Abhik Sen
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Jarin Hongpaisan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Chol S Lim
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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Sun MK, Nelson TJ, Alkon DL. Towards universal therapeutics for memory disorders. Trends Pharmacol Sci 2015; 36:384-94. [DOI: 10.1016/j.tips.2015.04.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 12/22/2022]
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Lucke-Wold BP, Turner RC, Logsdon AF, Simpkins JW, Alkon DL, Smith KE, Chen YW, Tan Z, Huber JD, Rosen CL. Common mechanisms of Alzheimer's disease and ischemic stroke: the role of protein kinase C in the progression of age-related neurodegeneration. J Alzheimers Dis 2015; 43:711-24. [PMID: 25114088 PMCID: PMC4446718 DOI: 10.3233/jad-141422] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ischemic stroke and Alzheimer's disease (AD), despite being distinct disease entities, share numerous pathophysiological mechanisms such as those mediated by inflammation, immune exhaustion, and neurovascular unit compromise. An important shared mechanistic link is acute and chronic changes in protein kinase C (PKC) activity. PKC isoforms have widespread functions important for memory, blood-brain barrier maintenance, and injury repair that change as the body ages. Disease states accelerate PKC functional modifications. Mutated forms of PKC can contribute to neurodegeneration and cognitive decline. In some cases the PKC isoforms are still functional but are not successfully translocated to appropriate locations within the cell. The deficits in proper PKC translocation worsen stroke outcome and amyloid-β toxicity. Cross talk between the innate immune system and PKC pathways contribute to the vascular status within the aging brain. Unfortunately, comorbidities such as diabetes, obesity, and hypertension disrupt normal communication between the two systems. The focus of this review is to highlight what is known about PKC function, how isoforms of PKC change with age, and what additional alterations are consequences of stroke and AD. The goal is to highlight future therapeutic targets that can be applied to both the treatment and prevention of neurologic disease. Although the pathology of ischemic stroke and AD are different, the similarity in PKC responses warrants further investigation, especially as PKC-dependent events may serve as an important connection linking age-related brain injury.
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Affiliation(s)
- Brandon P. Lucke-Wold
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Ryan C. Turner
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Aric F. Logsdon
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV, USA
| | - James W. Simpkins
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Daniel L. Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Kelly E. Smith
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV, USA
| | - Yi-Wen Chen
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Zhenjun Tan
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Jason D. Huber
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV, USA
| | - Charles L. Rosen
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV, USA
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
- Correspondence to: Charles L. Rosen, MD, PhD, Department of Neurosurgery, West Virginia University School of Medicine, One Medical Center Drive, Suite 4300, Health Sciences Center, PO Box 9183, Morgantown, WV 26506-9183, USA. Tel.: +1 304 293 5041; Fax: +1 304 293 4819;
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Chirila FV, Khan TK, Alkon DL. Fibroblast Aggregation Rate Converges with Validated Peripheral Biomarkers for Alzheimer's Disease. ACTA ACUST UNITED AC 2014; 42:1279-94. [DOI: 10.3233/jad-140672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | - Tapan K. Khan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
| | - Daniel L. Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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Lim CS, Alkon DL. PKCε promotes HuD-mediated neprilysin mRNA stability and enhances neprilysin-induced Aβ degradation in brain neurons. PLoS One 2014; 9:e97756. [PMID: 24848988 PMCID: PMC4029802 DOI: 10.1371/journal.pone.0097756] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 04/23/2014] [Indexed: 01/12/2023] Open
Abstract
Amyloid-beta (Aβ) peptide accumulation in the brain is a pathological hallmark of all forms of Alzheimer’s disease. An imbalance between Aβ production and clearance from the brain may contribute to accumulation of neurotoxic Aβ and subsequent synaptic loss, which is the strongest correlate of the extent of memory loss in AD. The activity of neprilysin (NEP), a potent Aβ-degrading enzyme, is decreased in the AD brain. Expression of HuD, an mRNA-binding protein important for synaptogenesis and neuronal plasticity, is also decreased in the AD brain. HuD is regulated by protein kinase Cε (PKCε), and we previously demonstrated that PKCε activation decreases Aβ levels. We hypothesized that PKCε acts through HuD to stabilize NEP mRNA, modulate its localization, and support NEP activity. Conversely, loss of PKCε-activated HuD in AD leads to decreased NEP activity and accumulation of Aβ. Here we show that HuD is associated with NEP mRNA in cultures of human SK-N-SH cells. Treatment with bryostatin, a PKCε-selective activator, enhanced NEP association with HuD and increased NEP mRNA stability. Activation of PKCε also increased NEP protein levels, increased NEP phosphorylation, and induced cell surface expression. In addition, specific PKCε activation directly stimulated NEP activity, leading to degradation of a monomeric form of Aβ peptide and decreased Aβ neuronal toxicity, as measured by cell viability. Bryostatin treatment also rescued Aβ-mediated inhibition of HuD-NEP mRNA binding, NEP protein expression, and NEP cell membrane translocation. These results suggest that PKCε activation reduces Aβ by up-regulating, via the mRNA-binding protein HuD, Aβ-degrading enzymes such as NEP. Thus, PKCε activation may have therapeutic efficacy for AD by reducing neurotoxic Aβ accumulation as well as having direct anti-apoptotic and synaptogenic effects.
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Affiliation(s)
- Chol Seung Lim
- Blanchette Rockefeller Neurosciences Institute at West Virginia University, Morgantown, West Virginia, United States of America
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute at West Virginia University, Morgantown, West Virginia, United States of America
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Sun MK, Hongpaisan J, Lim CS, Alkon DL. Bryostatin-1 Restores Hippocampal Synapses and Spatial Learning and Memory in Adult Fragile X Mice. J Pharmacol Exp Ther 2014; 349:393-401. [DOI: 10.1124/jpet.114.214098] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Xu C, Liu QY, Alkon DL. PKC activators enhance GABAergic neurotransmission and paired-pulse facilitation in hippocampal CA1 pyramidal neurons. Neuroscience 2014; 268:75-86. [PMID: 24637095 DOI: 10.1016/j.neuroscience.2014.03.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 03/05/2014] [Accepted: 03/06/2014] [Indexed: 11/18/2022]
Abstract
Bryostatin-1, a potent agonist of protein kinase C (PKC), has recently been found to enhance spatial learning and long-term memory in rats, mice, rabbits and the nudibranch Hermissenda, and to exert profound neuroprotective effects on Alzheimer's disease (AD) in transgenic mice. However, details of the mechanistic effects of bryostatin on learning and memory remain unclear. To address this issue, whole-cell recording, a dual-recording approach and extracellular recording techniques were performed on young (2-4months) Brown-Norway rats. We found that bath-applied bryostatin-1 significantly increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). The firing rate of GABAergic interneurons significantly was also increased as recorded with a loosely-attached extracellular recording configuration. Simultaneous recordings from communicating cell pairs of interneuron and pyramidal neuron revealed unique activity-dependent properties of GABAergic synapses. Furthermore, the bryostatin-induced increase of the frequency and amplitude of IPSCs was blocked by methionine enkephalin which selectively suppressed the excitability of interneurons. Pretreatment with RO-32-0432, a relatively specific PKCα antagonist, blocked the effect of bryostatin on sIPSCs. Finally, bryostatin increased paired-pulse ratio of GABAergic synapses that lasted for at least 20min while pretreatment with RO-32-0432 significantly reduced the ratio. In addition, 8-[2-(2-pentyl-cyclopropylmethl)-cyclopropyl]-octanoic acid (DCP-LA), a selective PKCε activator, also increased the frequency and amplitude of sIPSCs. Taken together, these results suggest that bryostatin enhances GABAergic neurotransmission in pyramidal neurons by activating the PKCα & ε-dependent pathway and by a presynaptic mechanism with excitation of GABAergic interneurons. These effects of bryostatin on GABAergic transmissions and modifiability may contribute to the improvement of learning and memory previously observed to be induced by bryostatin.
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Affiliation(s)
- C Xu
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV 26506, United States of America.
| | - Q-Y Liu
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV 26506, United States of America
| | - D L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV 26506, United States of America
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Takigami S, Sunada H, Lukowiak K, Kuzirian AM, Alkon DL, Sakakibara M. Protein kinase C mediates memory consolidation of taste avoidance conditioning in Lymnaea stagnalis. Neurobiol Learn Mem 2014; 111:9-18. [PMID: 24613854 DOI: 10.1016/j.nlm.2014.02.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 02/05/2014] [Accepted: 02/23/2014] [Indexed: 11/25/2022]
Abstract
In Lymnaea stagnalis, in order to obtain a 10 min short-term memory (STM) of taste avoidance conditioning (TAC) at least 10 paired presentations of a conditioned stimulus (CS), sucrose, and an unconditioned stimulus (US), tactile stimulation to the animal's head, are required. Pre-exposure of snails to the protein kinase C (PKC) α and ε activator bryostatin (Bryo) facilitated STM formation in that only 5 paired CS-US trials were required. Typically 20 paired presentations of the CS-US are required for formation of STM and LTM. However, 20 paired presentations do not result in STM or LTM if snails are pre-incubated with a PKC inhibitor, Ro-32-0432. We also found that LTM lasting longer than 48 h was acquired with Bryo incubation for 45 min even after termination of the conditioning paradigm. These data suggest that activation of the α and ε isozymes of PKC is crucially involved in the formation of LTM and provide further support for a mechanism that has been conserved across the evolution of species ranging from invertebrate molluscs to higher mammals.
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Affiliation(s)
- Satoshi Takigami
- Graduate School of Bioscience, Tokai University, 410-0321 Numazu, Shizuoka, Japan
| | - Hiroshi Sunada
- Hotchkiss Brain Institute, University of Calgary, Faculty of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Faculty of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Alan M Kuzirian
- Program in Sensory Physiology & Behavior, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neuroscience Institute, 9601 Medical Center Drive, Rockville, MD 20850-3332, USA
| | - Manabu Sakakibara
- Graduate School of Bioscience, Tokai University, 410-0321 Numazu, Shizuoka, Japan; School of High-Technology for Human Welfare, Tokai University, 410-0321 Numazu, Shizuoka, Japan.
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Nelson TJ, Sen A, Alkon DL, Sun MK. Adduct formation in liquid chromatography-triple quadrupole mass spectrometric measurement of bryostatin 1. J Chromatogr B Analyt Technol Biomed Life Sci 2013; 944:55-62. [PMID: 24291721 DOI: 10.1016/j.jchromb.2013.11.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 11/05/2013] [Accepted: 11/10/2013] [Indexed: 11/25/2022]
Abstract
Bryostatin 1, a potential anti-Alzheimer drug, is effective at subnanomolar concentrations. Measurement is complicated by the formation of low m/z degradation products and the formation of adducts with various cations, which make accurate quantitation difficult. Adduct formation caused the sample matrix or mobile phase to partition bryostatin 1 into products of different mass. Degradation of the 927 [M+Na](+) ion to a 869m/z product was strongly influenced by ionization conditions. We validated a bryostatin 1 assay in biological tissues using capillary column HPLC with nanospray ionization (NSI) in a triple-quadrupole mass spectrometer in selected reaction monitoring (SRM) mode. Adduct formation was controlled by adding 1mM acetic acid and 0.1mM sodium acetate to the HPLC buffer, maximizing the formation of the [M+Na](+) ion. Efficient removal of contaminating cholesterol from the sample during solvent extraction was also critical. The increased sensitivity provided by NSI and capillary-bore columns and the elimination of signal partitioning due to adduct formation and degradation in the ionization source enabled a detection limit of 1×10(-18)mol of bryostatin 1 and a LLOQ of 3×10(-18)mol from 1μl of sample. Bryostatin 1 at low pmol/l concentrations enabled measurement in brain and other tissues without the use of radioactive labels. Despite bryostatin 1's high molecular weight, considerable brain access was observed, with peak brain concentrations exceeding 8% of the peak blood plasma concentrations. Bryostatin 1 readily crosses the blood-brain barrier, reaching peak concentrations of 0.2nM, and specifically activates and translocates brain PKCɛ.
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Affiliation(s)
- Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV 26505, USA.
| | - Abhik Sen
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV 26505, USA
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV 26505, USA
| | - Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, 8 Medical Center Drive, Morgantown, WV 26505, USA
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Tan Z, Turner RC, Leon RL, Li X, Hongpaisan J, Zheng W, Logsdon AF, Naser ZJ, Alkon DL, Rosen CL, Huber JD. Bryostatin improves survival and reduces ischemic brain injury in aged rats after acute ischemic stroke. Stroke 2013; 44:3490-7. [PMID: 24172582 DOI: 10.1161/strokeaha.113.002411] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND AND PURPOSE Bryostatin, a potent protein kinase C (PKC) activator, has demonstrated therapeutic efficacy in preclinical models of associative memory, Alzheimer disease, global ischemia, and traumatic brain injury. In this study, we tested the hypothesis that administration of bryostatin provides a therapeutic benefit in reducing brain injury and improving stroke outcome using a clinically relevant model of cerebral ischemia with tissue plasminogen activator reperfusion in aged rats. METHODS Acute cerebral ischemia was produced by reversible occlusion of the right middle cerebral artery (MCAO) in 18- to 20-month-old female Sprague-Dawley rats using an autologous blood clot with tissue plasminogen activator-mediated reperfusion. Bryostatin was administered at 6 hours post-MCAO, then at 3, 6, 9, 12, 15, and 18 days after MCAO. Functional assessment was conducted at 2, 7, 14, and 21 days after MCAO. Lesion volume and hemispheric swelling/atrophy were performed at 2, 7, and 21 days post-MCAO. Histological assessment of PKC isozymes was performed at 24 hours post-MCAO. RESULTS Bryostatin-treated rats showed improved survival post-MCAO, especially during the first 4 days. Repeated administration of bryostatin post-MCAO resulted in reduced infarct volume, hemispheric swelling/atrophy, and improved neurological function at 21 days post-MCAO. Changes in αPKC expression and εPKC expression in neurons were noted in bryostatin-treated rats at 24 hours post-MCAO. CONCLUSIONS Repeated bryostatin administration post-MCAO protected the brain from severe neurological injury post-MCAO. Bryostatin treatment improved survival rate, reduced lesion volume, salvaged tissue in infarcted hemisphere by reducing necrosis and peri-infarct astrogliosis, and improved functional outcome after MCAO.
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Affiliation(s)
- Zhenjun Tan
- From the Department of Neurosurgery, School of Medicine (Z.T., R.C.T., R.L.L., X.L., Z.J.N., C.L.R.), Blanchette Rockefeller Neuroscience Institute (J.H., W.Z., D.L.A.), and Department of Basic Pharmaceutical Science, School of Pharmacy (A.F.L., J.D.H.), West Virginia University Health Sciences Center, Morgantown, WV
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Abstract
Drugs to treat Alzheimer's disease (AD) have been unsuccessful in preventing its devastating cognitive deficits and progressive neurodegeneration. The lack of a definitive diagnostic for AD has been a major obstacle to AD drug discovery. Here, we describe a novel, highly accurate peripheral diagnostic for AD patients based on quantitatively measured complexity of skin-sampled fibroblast networks. A significant number of samples were studied under double-blind conditions and had autopsy and/or genetic validation. An additional sample confirmed the diagnostic discrimination on freshly obtained skin samples. A sub-sample of these diagnostic differences were induced by oligomerized amyloid-β1-42. Based on the accuracy of these measures that utilize physical principles such as fractal dimension and lacunarity as well as the significant correlation with disease duration, this biomarker profile appears to identify accurately AD patients for therapeutic intervention.
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Affiliation(s)
- Florin V Chirila
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV 26506, USA
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32
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Hongpaisan J, Xu C, Sen A, Nelson TJ, Alkon DL. PKC activation during training restores mushroom spine synapses and memory in the aged rat. Neurobiol Dis 2013; 55:44-62. [DOI: 10.1016/j.nbd.2013.03.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 03/14/2013] [Accepted: 03/19/2013] [Indexed: 01/24/2023] Open
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Lim CS, Alkon DL. Protein kinase C stimulates HuD-mediated mRNA stability and protein expression of neurotrophic factors and enhances dendritic maturation of hippocampal neurons in culture. Hippocampus 2012; 22:2303-19. [DOI: 10.1002/hipo.22048] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2012] [Indexed: 01/19/2023]
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Sen A, Alkon DL, Nelson TJ. Apolipoprotein E3 (ApoE3) but not ApoE4 protects against synaptic loss through increased expression of protein kinase C epsilon. J Biol Chem 2012; 287:15947-58. [PMID: 22427674 DOI: 10.1074/jbc.m111.312710] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Synaptic loss is the earliest pathological change in Alzheimer disease (AD) and is the pathological change most directly correlated with the degree of dementia. ApoE4 is the major genetic risk factor for the age-dependent form of AD, which accounts for 95% of cases. Here we show that in synaptic networks formed from primary hippocampal neurons in culture, apoE3, but not apoE4, prevents the loss of synaptic networks produced by amyloid β oligomers (amylospheroids). Specific activators of PKCε, such as 8-(2-(2-pentyl-cyclopropylmethyl)-cyclopropyl)-octanoic acid methyl ester and bryostatin 1, protected against synaptic loss by amylospheroids, whereas PKCε inhibitors blocked this synaptic protection and also blocked the protection by apoE3. Blocking LRP1, an apoE receptor on the neuronal membrane, also blocked the protection by apoE. ApoE3, but not apoE4, induced the synthesis of PKCε mRNA and expression of the PKCε protein. Amyloid β specifically blocked the expression of PKCε but had no effect on other isoforms. These results suggest that protection against synaptic loss by apoE is mediated by a novel intracellular PKCε pathway. This apoE pathway may account for much of the protective effect of apoE and reduced risk for the age-dependent form of AD. This finding supports the potential efficacy of newly developed therapeutics for AD.
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Affiliation(s)
- Abhik Sen
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505, USA
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35
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Abstract
Memories are much more easily impaired than improved. Dementias, a lasting impairment of memory function, occur in a variety of cognitive disorders and become more clinically dominant as the population ages. Protein kinase C is one of the "cognitive kinases," and plays an essential role in both memory acquisition and maintenance. Deficits in protein kinase C (PKC) signal cascades in neurons represent one of the earliest changes in the brains of patients with Alzheimer's disease (AD) and other types of memory impairment, including those related to cerebral ischemia and ischemic stroke. Inhibition or impairment of PKC activity results in compromised learning and memory, whereas an appropriate activation of certain PKC isozymes leads to an enhancement of learning and memory and/or antidementic effects. In preclinical studies, PKC activators have been shown to increase the expression and activity of PKC isozymes, thereby restoring PKC signaling and downstream activity, including stimulation of neurotrophic activity, synaptic/structural remodeling, and synaptogenesis in the hippocampus and related cortical areas. PKC activators also reduce the accumulation of neurotoxic amyloid and tau protein hyperphosphorylation and support anti-apoptotic processes in the brain. These observations strongly suggest that PKC pharmacology may represent an attractive area for the development of effective cognition-enhancing therapeutics for the treatment of dementias.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA
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36
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Alkon DL. New developments in the search for a cure. W V Med J 2011; 107:10-13. [PMID: 21702408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, West Virginia University School of Medicine, USA
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37
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Abstract
Three days of training consisting of trials of light paired with rotation produces a long-term modification of photopositive behavior in Hermissenda crassicornis. The behavioral modification depends on the temporal association of light and rotation. For animals that received light paired with rotation, significant increases in the spontaneous activity of type B photoreceptors were correlated with changes in photopositive behavior after training. A persistent tonic depolarization of type B photoreceptors can explain the cellular changes correlated with the long-term behavioral modification produced by the temporal association of light and rotation.
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Sun MK, Alkon DL. Pharmacology of protein kinase C activators: cognition-enhancing and antidementic therapeutics. Pharmacol Ther 2010; 127:66-77. [PMID: 20382181 DOI: 10.1016/j.pharmthera.2010.03.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 03/25/2010] [Indexed: 11/17/2022]
Abstract
Evidence is accumulating indicating that some protein kinase C (PKC) isozymes play an essential role in various phases as well as types of learning and memory. Abnormal functions of PKC signal cascades in the brains have been found to represent one of the earliest changes in patients with Alzheimer's disease (AD) and other types of memory deficits, including those related to cerebral ischemic/stroke events. In preclinical studies, an inhibition or impairment of PKC activity leads to compromised learning and memory, whereas an appropriate activation of some PKC isozymes results in an enhancement of learning and memory and/or antidementic effects against memory disorders. PKC activators not only increase activity of PKC isozymes and thereby restore PKC signaling activity, including neurotrophic activity, synaptic/structural remodeling, and synaptogenesis in the hippocampus and related cortical areas, but also reduce the accumulation of neurotoxic amyloid and tau protein hyperphosphorylation in the brain. These observations strongly suggest that PKC isoform pharmacology may represent an attractive area for the development of cognition-enhancing agents and therapeutics against memory loss in the future.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, 9601 Medical Center Drive, Academic and Research Building, Rockville, MD 20850, USA.
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Abstract
The last decade has witnessed a rapid progress in understanding of the molecular cascades that may underlie memory and memory disorders. Among the critical players, activity of protein kinase C (PKC) isoforms is essential for many types of learning and memory and their dysfunction, and is critical in memory disorders. PKC inhibition and functional deficits lead to an impairment of various types of learning and memory, consistent with the observations that neurotoxic amyloid inhibits PKC activity and that transgenic animal models with PKCbeta deficit exhibit impaired capacity in cognition. In addition, PKC isozymes play a regulatory role in amyloid production and accumulation. Restoration of the impaired PKC signal pathway pharmacologically results in an enhanced memory capacity and synaptic remodeling / repair and synaptogenesis, and, therefore, represents a potentially important strategy for the treatment of memory disorders, including Alzheimer's dementia. The PKC activators, especially those that are isozyme-specific, are a new class of drug candidates that may be developed as future memory therapeutics.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Rockville, MD 20850, USA.
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Sun MK, Nelson TJ, Alkon DL. PKC and Insulin Pathways in Memory Storage: Targets for Synaptogenesis, Anti-apoptosis, and the Treatment of AD. Diabetes, Insulin and Alzheimer's Disease 2010. [DOI: 10.1007/978-3-642-04300-0_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Nelson TJ, Cui C, Luo Y, Alkon DL. Reduction of beta-amyloid levels by novel protein kinase C(epsilon) activators. J Biol Chem 2009; 284:34514-21. [PMID: 19850930 PMCID: PMC2787312 DOI: 10.1074/jbc.m109.016683] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 10/20/2009] [Indexed: 12/12/2022] Open
Abstract
Isoform-specific protein kinase C (PKC) activators may be useful as therapeutic agents for the treatment of Alzheimer disease. Three new epsilon-specific PKC activators, made by cyclopropanation of polyunsaturated fatty acids, have been developed. These activators, AA-CP4, EPA-CP5, and DHA-CP6, activate PKCepsilon in a dose-dependent manner. Unlike PKC activators that bind to the 1,2-diacylglycerol-binding site, such as bryostatin and phorbol esters, which produce prolonged down-regulation, the new activators produced sustained activation of PKC. When applied to cells expressing human APPSwe/PS1delta, which produce large quantities of beta-amyloid peptide (Abeta), DCP-LA and DHA-CP6 reduced the intracellular and secreted levels of Abeta by 60-70%. In contrast to the marked activation of alpha-secretase produced by PKC activators in fibroblasts, the PKC activators produced only a moderate and transient activation of alpha-secretase in neuronal cells. However, they activated endothelin-converting enzyme to 180% of control levels, suggesting that the Abeta-lowering ability of these PKCepsilon activators is caused by increasing the rate of Abeta degradation by endothelin-converting enzyme and not by activating nonamyloidogenic amyloid precursor protein metabolism.
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Affiliation(s)
- Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26506, USA.
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42
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Xu C, Cui C, Alkon DL. Age-dependent enhancement of inhibitory synaptic transmission in CA1 pyramidal neurons via GluR5 kainate receptors. Hippocampus 2009; 19:706-17. [PMID: 19123252 DOI: 10.1002/hipo.20544] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Changes in hippocampal synaptic networks during aging may contribute to age-dependent compromise of cognitive functions such as learning and memory. Previous studies have demonstrated that GABAergic synaptic transmission exhibits age-dependent changes. To better understand such age-dependent changes of GABAergic synaptic inhibition, we performed whole-cell recordings from pyramidal cells in the CA1 area of acute hippocampal slices on aged (24-26 months old) and young (2-4 months old) Brown-Norway rats. We found that the frequency and amplitude of spontaneous inhibitory postsynaptic current (IPSCs) were significantly increased in aged rats, but the frequency and amplitude of mIPSCs were decreased. Furthermore, the regulation of GABAergic synaptic transmission by GluR5 containing kainate receptors was enhanced in aged rats, which was revealed by using LY382884 (a GluR5 kainate receptor antagonist) and ATPA (a GluR5 kainate receptor agonist). Moreover, we demonstrated that vesicular glutamate transporters are involved in the kainate receptor dependent regulation of sIPSCs. Taken together, these results suggest that GABAergic synaptic transmission is potentiated in aged rats, and GluR5 containing kainate receptors regulate the inhibitory synaptic transmission through endogenous glutamate. These alterations of GABAergic input with aging could contribute to age-dependent cognitive decline.
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Affiliation(s)
- Changqing Xu
- Blanchette Rockefeller Neurosciences Institute, Rockville, Maryland 20850-3332, USA.
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43
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Nelson TJ, Alkon DL. Neuroprotective versus tumorigenic protein kinase C activators. Trends Biochem Sci 2009; 34:136-45. [PMID: 19233655 DOI: 10.1016/j.tibs.2008.11.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
Abstract
Protein kinase C (PKC) activators possess potent neurotrophic and neuroprotective activity, thus indicating potential applications in treating neurodegenerative diseases, stroke and traumatic brain injury. Although some activators, such as bryostatin and gnidimacrin, have been tested as antitumor agents, others, such as phorbol esters, are potent tumor promoters. All PKC activators downregulate PKC at high concentrations and long application times. However, tumorigenic activators downregulate certain PKC isozymes, especially PKCdelta, more strongly. Tumorigenic activators possess unique structural features that could account for this difference. At concentrations that minimize PKC downregulation, PKC activators can improve long-term memory, reduce beta-amyloid levels, induce synaptogenesis, promote neuronal repair and inhibit cell proliferation. Intermittent, low concentrations of structurally specific, non-tumorigenic PKC activators, therefore, could offer therapeutic benefit for a variety of neurologic disorders.
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Affiliation(s)
- T J Nelson
- Blanchette Rockefeller Neurosciences Institute, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
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Khan TK, Nelson TJ, Verma VA, Wender PA, Alkon DL. A cellular model of Alzheimer's disease therapeutic efficacy: PKC activation reverses Abeta-induced biomarker abnormality on cultured fibroblasts. Neurobiol Dis 2009; 34:332-9. [PMID: 19233276 DOI: 10.1016/j.nbd.2009.02.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2008] [Accepted: 02/03/2009] [Indexed: 12/21/2022] Open
Abstract
PKC signaling is critical for the non-toxic degradation of amyloid precursor protein (APP) and inhibition of GSK3beta, which controls phosphorylation of tau protein in Alzheimer's disease (AD). Thus the misregulation of PKC signaling could contribute to the origins of AD. Bryostatin, a potent PKC modulator, has the potential to ameliorate both the neurodegeneration and the recent memory loss associated with AD. As reported herein bryostatin and a potent synthetic analog (picolog) are found to cause stimulation of non-amyloidogenic pathways by increasing alpha-secretase activity and thus lowering the amount of toxic Abeta produced. Both bryostatin and picolog increased the secretion of the alpha-secretase product (s-APP-alpha) of APP at sub-nanomolar to nanomolar concentrations. A peripheral AD-Biomarker has previously been autopsy-validated. This Biomarker, based on bradykinin-induced differential phosphorylation of Erk1 and Erk2, has been used here to test the therapeutic efficacy both for bryostatin and picolog. Both of these PKC activators are then shown to convert the AD Erk1/2 phenotype of fibroblasts into the phenotype of "normal" control skin fibroblasts. This conversion occurred for both the abnormal Erk1/2 phenotype induced by application of Abeta(1-42) to the fibroblasts or the phenotype observed for fibroblasts of AD patients. The Abeta(1-42)-induction, and PKC modulator reversal of the AD Erk1/2 biomarker phenotype demonstrate the AD-Biomarker's potential to monitor both disease progression and treatment response. Additionally, this first demonstration of the therapeutic potential in AD of a synthetically accessible bryostatin analog warrants further preclinical advancement.
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Affiliation(s)
- Tapan K Khan
- Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, 26506, USA.
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45
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Khan TK, Alkon DL. Early diagnostic accuracy and pathophysiologic relevance of an autopsy-confirmed Alzheimer's disease peripheral biomarker. Neurobiol Aging 2008; 31:889-900. [PMID: 18760507 DOI: 10.1016/j.neurobiolaging.2008.07.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 07/10/2008] [Accepted: 07/11/2008] [Indexed: 11/28/2022]
Abstract
Treatment of Alzheimer's disease (AD) and the discovery of promising drug candidates depend on early diagnosis. Few currently available diagnostic tests have significantly improved this early uncertainty, while the "gold standard" diagnosis continues to require clinical dementia in life and the presence of pathologic brain lesions of amyloid plaques and neurofibrillary tangles in the brain at autopsy. Here, the inflammatory agonist bradykinin, a small nano-peptide, that induces PKC-mediated phosphorylation of Erk1 and Erk2 in fibroblasts, was applied to punch-biopsy-obtained human skin fibroblasts. Quantitative imaging of the phosphorylated Erk1 and Erk2 bands was then used in a ratio that is mathematically configured into an AD-Biomarker Index (AD-Index). In the population described here (N=264), there were 64 autopsy examinations. Demented individuals were clinically diagnosed as AD with an overall accuracy of 78%. Among the 42 autopsy-confirmed cases for which there were also AD-Biomarker measurements, the overall accuracy of the AD-Biomarker was 98%. Among both the autopsy-confirmed and the clinically diagnosed patients, the AD-Index values were inversely correlated with the duration of disease, i.e., the time from the onset of dementia symptoms. Among the autopsy-confirmed cases, the AD-Biomarker diagnosis showed remarkably high sensitivity (97%) and specificity (100%) compared to clinical diagnosis (sensitivity: 78% and specificity: 20%). Using autopsy validation, the clinical diagnosis was only accurate at 52% level vs. the AD-Biomarker accuracy of 100% for cases with dementia not larger than 4 years of duration. Finally, application of soluble Abeta(1-42) to the fibroblasts of normal controls induced the abnormal AD-Biomarker phenotype, suggesting the pathophysiologic relevance of this AD-Biomarker measurement. In summary, the AD-Biomarker, as confirmed by autopsy validation, showed significantly higher sensitivity and specificity than did clinical diagnosis, particularly at early stages of disease, and pathophysiological relevance was demonstrated for the mechanistic basis of the AD-Biomarker measurements.
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Affiliation(s)
- Tapan Kumar Khan
- Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV 26506-9301, USA
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Ito E, Oka K, Collin C, Schreurs BG, Sakakibara M, Alkon DL. Tumor Necrosis Factor-α (TNF-α), Interferon-γ, and Interleukin-6 but Not TNF-β Induce Differentiation of Neuroblastoma Cells: The Role of Nitric Oxide. J Neurochem 2008. [DOI: 10.1046/j.1471-4159.1994.62041337.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Micale V, Scapagnini G, Colombrita C, Mazzola C, Alkon DL, Drago F. Behavioral effects of dietary cholesterol in rats tested in experimental models of mild stress and cognition tasks. Eur Neuropsychopharmacol 2008; 18:462-71. [PMID: 18222653 DOI: 10.1016/j.euroneuro.2007.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2007] [Revised: 09/03/2007] [Accepted: 11/21/2007] [Indexed: 11/17/2022]
Abstract
Abnormalities in serum cholesterol levels of patients with mood disorders have been identified in epidemiological studies. However, evidence for an influence of dietary cholesterol on behavioral models is poor. Here, we investigated the behavioral changes of Wistar male rats fed a 2% cholesterol-enriched diet for 2 months in experimental models of depression and anxiety, such as the forced swim test (FST) paradigm and the novelty-induced grooming sampling test (NGT). The correlation between behavioral depression and impaired cognitive capacity was also examined testing rats in the Morris water maze (MWM) task one day after the FST. Different groups of rats fed various dietary regimens, were subjected to acute or repeated treatment (14 days) with clomipramine hydrochloride (50 or 25 mg/kg), diazepam (1 mg/kg) or with the peripheral benzodiazepine receptors (PBRs) antagonist, isoquinoline PK11195 (1 mg/kg) injected intraperitoneally (i.p.). Rats fed the cholesterol-enriched diet showed a significant decrease of grooming score in the NGT and of immobility time in the FST in comparison to animals fed a standard diet. Furthermore, the anxiolytic and antidepressant effects of diazepam and clomipramine were not affected by the different diets. Only after repeated treatment, PK11195 impaired the performance of animals fed a standard diet in the FST, and exhibited an anxiolytic-like profile in animals fed either the cholesterol-enriched or the standard diet. The improved performance in the FST was followed by a better learning performance in the acquisition phase of the MWM. These results suggest that effects of cholesterol-enriched diet on the behavioral reaction of rats in experimental models of mild stress may involve PBRs. They deserve attention in order to clarify the clinical correlation between plasma cholesterol levels and mood disorders in humans.
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MESH Headings
- Analysis of Variance
- Animals
- Antidepressive Agents, Tricyclic/therapeutic use
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Behavior, Animal/drug effects
- Cholesterol, Dietary/pharmacology
- Cholesterol, Dietary/therapeutic use
- Clomipramine/therapeutic use
- Cognition/drug effects
- Cognition/physiology
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Grooming/drug effects
- Grooming/physiology
- Immobility Response, Tonic/drug effects
- Immobility Response, Tonic/physiology
- Isoquinolines/pharmacology
- Isoquinolines/therapeutic use
- Male
- Maze Learning/drug effects
- Maze Learning/physiology
- Rats
- Rats, Wistar
- Stress, Psychological/diet therapy
- Stress, Psychological/drug therapy
- Swimming
- Time Factors
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Affiliation(s)
- Vincenzo Micale
- Department of Experimental and Clinical Pharmacology, University of Catania, Catania, Italy
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Sun MK, Alkon DL. Synergistic effects of chronic bryostatin-1 and α-tocopherol on spatial learning and memory in rats. Eur J Pharmacol 2008; 584:328-37. [DOI: 10.1016/j.ejphar.2008.02.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 01/16/2008] [Accepted: 02/06/2008] [Indexed: 10/22/2022]
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Nelson TJ, Sun MK, Hongpaisan J, Alkon DL. Insulin, PKC signaling pathways and synaptic remodeling during memory storage and neuronal repair. Eur J Pharmacol 2008; 585:76-87. [PMID: 18402935 DOI: 10.1016/j.ejphar.2008.01.051] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 11/29/2007] [Accepted: 01/21/2008] [Indexed: 01/04/2023]
Abstract
Protein kinase C (PKC) is involved in synaptic remodeling, induction of protein synthesis, and many other processes important in learning and memory. Activation of neuronal protein kinase C correlates with, and may be essential for, all phases of learning, including acquisition, consolidation, and reconsolidation. Protein kinase C activation is closely tied to hydrolysis of membrane lipids. Phospholipases C and A2 produce 1,2-diacylglycerol and arachidonic acid, which are direct activators of protein kinase C. Phospholipase C also produces inositol triphosphate, which releases calcium from internal stores. Protein kinase C interacts with many of the same pathways as insulin; therefore, it should not be surprising that insulin signaling and protein kinase C activation can both have powerful effects on memory storage and synaptic remodeling. However, investigating the possible roles of insulin in memory storage can be challenging, due to the powerful peripheral effects of insulin on glucose and the low concentration of insulin in the brain. Although peripheral for insulin, synthesized in the beta-cells of the pancreas, is primarily involved in regulating glucose, small amounts of insulin are also present in the brain. The functions of this brain insulin are inadequately understood. Protein kinase C may also contribute to insulin resistance by phosphorylating the insulin receptor substrates required for insulin signaling. Insulin is also responsible insulin-long term depression, a type of synaptic plasticity that is also dependent on protein kinase C. However, insulin can also activate PKC signaling pathways via PLC gamma, Erk 1/2 MAP kinase, and src stimulation. Taken together, the available evidence suggests that the major impact of protein kinase C and its interaction with insulin in the mature, fully differentiated nervous system appears to be to induce synaptogenesis, enhance memory, reduce Alzheimer's pathophysiology, and stimulate neurorepair.
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Affiliation(s)
- Thomas J Nelson
- Blanchette Rockefeller Neurosciences Institute, 9601 Medical Center Drive, Rockville, Maryland 20850 USA
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Nelson TJ, Alkon DL. Protection against β-amyloid-induced apoptosis by peptides interacting with β-amyloid. VOLUME 282 (2007) PAGES 31238-31249. J Biol Chem 2008. [DOI: 10.1016/s0021-9258(20)57238-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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