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Mohammadkhani M, Gholami D, Riazi G. The effects of chronic morphine administration on spatial memory and microtubule dynamicity in male mice's brain. IBRO Neurosci Rep 2024; 16:300-308. [PMID: 38390235 PMCID: PMC10881431 DOI: 10.1016/j.ibneur.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 02/09/2024] [Indexed: 02/24/2024] Open
Abstract
The examination of the influence of morphine on behavioral processes, specifically learning and memory, holds significant importance. Additionally, microtubule proteins play a pivotal role in cellular functions, and the dynamics of microtubules contribute to neural network connectivity, information processing, and memory storage. however, the molecular mechanism of morphine on microtubule dynamics, learning, and memory remains uncovered. In the present study, we examined the effects of chronic morphine administration on memory formation impairment and the kinetic alterations in microtubule proteins induced by morphine in mice. Chronic morphine administration at doses of 5 and 10 mg/kg dose-dependently decreased subjects' performance in spatial memory tasks, such as the Morris Water Maze and Y-maze spontaneous alternation behavior. Furthermore, morphine was found to stabilize microtubule structure, and increase polymerization, and total polymer mass. However, it simultaneously impaired microtubule dynamicity, stemming from structural changes in tubulin dimer structure. These findings emphasize the need for careful consideration of different doses when using morphine, urging a more cautious approach in the administration of this opioid medication.
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Affiliation(s)
- Mina Mohammadkhani
- Department of Biochemistry, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | - Dariush Gholami
- Department of Microbial Biotechnology, Faculty of Biotechnology, Amol University of Special Modern Technologies, Amol, Iran
| | - Gholamhossein Riazi
- Department of Biochemistry, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
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2
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Kumar Nelson V, Jha NK, Nuli MV, Gupta S, Kanna S, Gahtani RM, Hani U, Singh AK, Abomughaid MM, Abomughayedh AM, Almutary AG, Iqbal D, Al Othaim A, Begum SS, Ahmad F, Mishra PC, Jha SK, Ojha S. Unveiling the impact of aging on BBB and Alzheimer's disease: Factors and therapeutic implications. Ageing Res Rev 2024; 98:102224. [PMID: 38346505 DOI: 10.1016/j.arr.2024.102224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 02/01/2024] [Accepted: 02/03/2024] [Indexed: 05/12/2024]
Abstract
Alzheimer's disease (AD) is a highly prevalent neurodegenerative condition that has devastating effects on individuals, often resulting in dementia. AD is primarily defined by the presence of extracellular plaques containing insoluble β-amyloid peptide (Aβ) and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein (P-tau). In addition, individuals afflicted by these age-related illnesses experience a diminished state of health, which places significant financial strain on their loved ones. Several risk factors play a significant role in the development of AD. These factors include genetics, diet, smoking, certain diseases (such as cerebrovascular diseases, obesity, hypertension, and dyslipidemia), age, and alcohol consumption. Age-related factors are key contributors to the development of vascular-based neurodegenerative diseases such as AD. In general, the process of aging can lead to changes in the immune system's responses and can also initiate inflammation in the brain. The chronic inflammation and the inflammatory mediators found in the brain play a crucial role in the dysfunction of the blood-brain barrier (BBB). Furthermore, maintaining BBB integrity is of utmost importance in preventing a wide range of neurological disorders. Therefore, in this review, we discussed the role of age and its related factors in the breakdown of the blood-brain barrier and the development of AD. We also discussed the importance of different compounds, such as those with anti-aging properties, and other compounds that can help maintain the integrity of the blood-brain barrier in the prevention of AD. This review builds a strong correlation between age-related factors, degradation of the BBB, and its impact on AD.
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Affiliation(s)
- Vinod Kumar Nelson
- Raghavendra Institute of Pharmaceutical Education and Research, Anantapur, India.
| | - Niraj Kumar Jha
- Centre for Global Health Research, Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, India; Centre of Research Impact and Outcome, Chitkara University, Rajpura 140401, Punjab, India; School of Bioengineering & Biosciences, Lovely Professional University, Phagwara 144411, India; Department of Biotechnology Engineering and Food Technology, Chandigarh University, Mohali, India.
| | - Mohana Vamsi Nuli
- Raghavendra Institute of Pharmaceutical Education and Research, Anantapur, India
| | - Saurabh Gupta
- Department of Biotechnology, GLA University, Mathura, Uttar Pradesh, India
| | - Sandeep Kanna
- Department of pharmaceutics, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Guntur 522034, India
| | - Reem M Gahtani
- Departement of Clinical Laboratory Sciences, King Khalid University, Abha, Saudi Arabia
| | - Umme Hani
- Department of pharmaceutics, College of Pharmacy, King Khalid University, Abha, Saudi Arabia
| | - Arun Kumar Singh
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology BHU, Varanasi, Uttar Pradesh, India
| | - Mosleh Mohammad Abomughaid
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, University of Bisha, Bisha 61922, Saudi Arabia
| | - Ali M Abomughayedh
- Pharmacy Department, Aseer Central Hospital, Ministry of Health, Saudi Arabia
| | - Abdulmajeed G Almutary
- Department of Biomedical Sciences, College of Health Sciences, Abu Dhabi University, Abu Dhabi, P.O. Box 59911, United Arab Emirates
| | - Danish Iqbal
- Department of Health Information Management, College of Applied Medical Sciences, Buraydah Private Colleges, Buraydah 51418, Saudi Arabia
| | - Ayoub Al Othaim
- Department of Medical Laboratory Sciences, College of Applied Medical Science, Majmaah University, Al-Majmaah 11952, Saudi Arabia.
| | - S Sabarunisha Begum
- Department of Biotechnology, P.S.R. Engineering College, Sivakasi 626140, India
| | - Fuzail Ahmad
- Respiratory Care Department, College of Applied Sciences, Almaarefa University, Diriya, Riyadh, 13713, Saudi Arabia
| | - Prabhu Chandra Mishra
- Department of Biotechnology, School of Engineering and Technology, Sharda University, Greater Noida, India
| | - Saurabh Kumar Jha
- Department of Zoology, Kalindi College, University of Delhi, 110008, India.
| | - Shreesh Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, P.O. Box 15551, United Arab Emirates
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3
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Pal R, Hui D, Menchen H, Zhao H, Mozziconacci O, Wilkins H, Blagg BSJ, Schöneich C, Swerdlow RH, Michaelis ML, Michaelis EK. Protection against Aβ-induced neuronal damage by KU-32: PDHK1 inhibition as important target. Front Aging Neurosci 2023; 15:1282855. [PMID: 38035268 PMCID: PMC10682733 DOI: 10.3389/fnagi.2023.1282855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 10/23/2023] [Indexed: 12/02/2023] Open
Abstract
A feature of most neurodegenerative diseases is the presence of "mis-folded proteins" that form aggregates, suggesting suboptimal activity of neuronal molecular chaperones. Heat shock protein 90 (Hsp90) is the master regulator of cell responses to "proteotoxic" stresses. Some Hsp90 modulators activate cascades leading to upregulation of additional chaperones. Novobiocin is a modulator at the C-terminal ATP-binding site of Hsp90. Of several novobiocin analogs synthesized and tested for protection against amyloid beta (Aβ)-induced neuronal death, "KU-32" was the most potent in protecting primary neurons, but did not increase expression of other chaperones believed to help clear misfolded proteins. However, KU-32 reversed Aβ-induced superoxide formation, activated Complex I of the electron transfer chain in mitochondria, and blocked the Aβ-induced inhibition of Complex I in neuroblastoma cells. A mechanism for these effects of KU-32 on mitochondrial metabolism appeared to be the inhibition of pyruvate dehydrogenase kinase (PDHK), both in isolated brain mitochondria and in SH-SY5Y cells. PDHK inhibition by the classic enzyme inhibitor, dichloroacetate, led to neuroprotection from Aβ25-35-induced cell injury similarly to KU-32. Inhibition of PDHK in neurons would lead to activation of the PDH complex, increased acetyl-CoA generation, stimulation of the tricarboxylic acid cycle and Complex I in the electron transfer chain, and enhanced oxidative phosphorylation. A focus of future studies may be on the potential value of PDHK as a target in AD therapy.
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Affiliation(s)
- Ranu Pal
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, United States
| | - Dongwei Hui
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, United States
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, United States
| | - Heather Menchen
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, United States
| | - Huiping Zhao
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, United States
| | - Olivier Mozziconacci
- University of Kansas Alzheimer’s Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States
| | - Heather Wilkins
- University of Kansas Alzheimer’s Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States
| | - Brian S. J. Blagg
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, United States
- Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, IN, United States
| | - Christian Schöneich
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, United States
| | - Russell H. Swerdlow
- University of Kansas Alzheimer’s Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States
| | - Mary L. Michaelis
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, United States
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, United States
- University of Kansas Alzheimer’s Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States
| | - Elias K. Michaelis
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, United States
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, United States
- University of Kansas Alzheimer’s Disease Research Center, University of Kansas Medical Center, Kansas City, KS, United States
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4
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Glycosylated clusterin species facilitate Aβ toxicity in human neurons. Sci Rep 2022; 12:18639. [PMID: 36329114 PMCID: PMC9633591 DOI: 10.1038/s41598-022-23167-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
Clusterin (CLU) is one of the most significant genetic risk factors for late onset Alzheimer's disease (AD). However, the mechanisms by which CLU contributes to AD development and pathogenesis remain unclear. Studies have demonstrated that the trafficking and localisation of glycosylated CLU proteins is altered by CLU-AD mutations and amyloid-β (Aβ), which may contribute to AD pathogenesis. However, the roles of non-glycosylated and glycosylated CLU proteins in mediating Aβ toxicity have not been studied in human neurons. iPSCs with altered CLU trafficking were generated following the removal of CLU exon 2 by CRISPR/Cas9 gene editing. Neurons were generated from control (CTR) and exon 2 -/- edited iPSCs and were incubated with aggregated Aβ peptides. Aβ induced changes in cell death and neurite length were quantified to determine if altered CLU protein trafficking influenced neuronal sensitivity to Aβ. Finally, RNA-Seq analysis was performed to identify key transcriptomic differences between CLU exon 2 -/- and CTR neurons. The removal of CLU exon 2, and the endoplasmic reticulum (ER)-signal peptide located within, abolished the presence of glycosylated CLU and increased the abundance of intracellular, non-glycosylated CLU. While non-glycosylated CLU levels were unaltered by Aβ25-35 treatment, the trafficking of glycosylated CLU was altered in control but not exon 2 -/- neurons. The latter also displayed partial protection against Aβ-induced cell death and neurite retraction. Transcriptome analysis identified downregulation of multiple extracellular matrix (ECM) related genes in exon 2 -/- neurons, potentially contributing to their reduced sensitivity to Aβ toxicity. This study identifies a crucial role of glycosylated CLU in facilitating Aβ toxicity in human neurons. The loss of these proteins reduced both, cell death and neurite damage, two key consequences of Aβ toxicity identified in the AD brain. Strikingly, transcriptomic differences between exon 2 -/- and control neurons were small, but a significant and consistent downregulation of ECM genes and pathways was identified in exon 2 -/- neurons. This may contribute to the reduced sensitivity of these neurons to Aβ, providing new mechanistic insights into Aβ pathologies and therapeutic targets for AD.
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Eshraghi M, Ahmadi M, Afshar S, Lorzadeh S, Adlimoghaddam A, Rezvani Jalal N, West R, Dastghaib S, Igder S, Torshizi SRN, Mahmoodzadeh A, Mokarram P, Madrakian T, Albensi BC, Łos MJ, Ghavami S, Pecic S. Enhancing autophagy in Alzheimer's disease through drug repositioning. Pharmacol Ther 2022; 237:108171. [PMID: 35304223 DOI: 10.1016/j.pharmthera.2022.108171] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/18/2022] [Accepted: 03/08/2022] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is one of the biggest human health threats due to increases in aging of the global population. Unfortunately, drugs for treating AD have been largely ineffective. Interestingly, downregulation of macroautophagy (autophagy) plays an essential role in AD pathogenesis. Therefore, targeting autophagy has drawn considerable attention as a therapeutic approach for the treatment of AD. However, developing new therapeutics is time-consuming and requires huge investments. One of the strategies currently under consideration for many diseases is "drug repositioning" or "drug repurposing". In this comprehensive review, we have provided an overview of the impact of autophagy on AD pathophysiology, reviewed the therapeutics that upregulate autophagy and are currently used in the treatment of other diseases, including cancers, and evaluated their repurposing as a possible treatment option for AD. In addition, we discussed the potential of applying nano-drug delivery to neurodegenerative diseases, such as AD, to overcome the challenge of crossing the blood brain barrier and specifically target molecules/pathways of interest with minimal side effects.
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Affiliation(s)
- Mehdi Eshraghi
- Department of Human Anatomy and Cell Science, University of Manitoba College of Medicine, Winnipeg, MB R3E 0V9, Canada
| | - Mazaher Ahmadi
- Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran; Autophagy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Saeid Afshar
- Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Shahrokh Lorzadeh
- Department of Human Anatomy and Cell Science, University of Manitoba College of Medicine, Winnipeg, MB R3E 0V9, Canada
| | - Aida Adlimoghaddam
- Autophagy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; St. Boniface Hospital Albrechtsen Research Centre, Division of Neurodegenerative Disorders, Winnipeg, MB R2H2A6, Canada
| | | | - Ryan West
- Department of Chemistry and Biochemistry, California State University, Fullerton, United States of America
| | - Sanaz Dastghaib
- Endocrinology and Metabolism Research Center, Shiraz University of Medical Sciences, Shiraz Iran
| | - Somayeh Igder
- Department of Clinical Biochemistry, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | | | - Amir Mahmoodzadeh
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah 6734667149, Iran
| | - Pooneh Mokarram
- Autophagy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Tayyebeh Madrakian
- Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran; Autophagy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Benedict C Albensi
- St. Boniface Hospital Albrechtsen Research Centre, Division of Neurodegenerative Disorders, Winnipeg, MB R2H2A6, Canada; Nova Southeastern Univ. College of Pharmacy, Davie, FL, United States of America; University of Manitoba, College of Medicine, Winnipeg, MB R3E 0V9, Canada
| | - Marek J Łos
- Biotechnology Center, Silesian University of Technology, 44-100 Gliwice, Poland
| | - Saeid Ghavami
- Department of Human Anatomy and Cell Science, University of Manitoba College of Medicine, Winnipeg, MB R3E 0V9, Canada; Autophagy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Research Institutes of Oncology and Hematology, Cancer Care Manitoba-University of Manitoba, Winnipeg, MB R3E 0V9, Canada; Biology of Breathing Theme, Children Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB R3E 0V9, Canada; Faculty of Medicine in Zabrze, University of Technology in Katowice, Academia of Silesia, 41-800 Zabrze, Poland
| | - Stevan Pecic
- Department of Chemistry and Biochemistry, California State University, Fullerton, United States of America.
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Boiarska Z, Passarella D. Microtubule-targeting agents and neurodegeneration. Drug Discov Today 2020; 26:604-615. [PMID: 33279455 DOI: 10.1016/j.drudis.2020.11.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/17/2020] [Accepted: 11/28/2020] [Indexed: 11/25/2022]
Abstract
The association of microtubule (MT) breakdown with neurodegeneration and neurotoxicity has provided an emerging therapeutic approach for neurodegenerative diseases. Tubulin binders are able to modulate MT dynamics and, as a result, are of particular interest both as potential therapeutics and experimental tools used to validate this strategy. Here, we provide a comprehensive overview of current knowledge and recent advancements regarding MT-targeting approaches for neurodegeneration and evaluate the potential application of MT-targeting agents (MTAs) based on available preclinical and clinical data.
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Affiliation(s)
- Zlata Boiarska
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Daniele Passarella
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy.
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Talwar P, Gupta R, Kushwaha S, Agarwal R, Saso L, Kukreti S, Kukreti R. Viral Induced Oxidative and Inflammatory Response in Alzheimer's Disease Pathogenesis with Identification of Potential Drug Candidates: A Systematic Review using Systems Biology Approach. Curr Neuropharmacol 2019; 17:352-365. [PMID: 29676229 PMCID: PMC6482477 DOI: 10.2174/1570159x16666180419124508] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 03/19/2018] [Accepted: 04/10/2018] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease (AD) is genetically complex with multifactorial etiology. Here, we aim to identify the potential viral pathogens leading to aberrant inflammatory and oxidative stress response in AD along with potential drug candidates using systems biology approach. We retrieved protein interactions of amyloid precursor protein (APP) and tau protein (MAPT) from NCBI and genes for oxidative stress from NetAge, for inflammation from NetAge and InnateDB databases. Genes implicated in aging were retrieved from GenAge database and two GEO expression datasets. These genes were individually used to create protein-protein interaction network using STRING database (score≥0.7). The interactions of candidate genes with known viruses were mapped using virhostnet v2.0 database. Drug molecules targeting candidate genes were retrieved using the Drug- Gene Interaction Database (DGIdb). Data mining resulted in 2095 APP, 116 MAPT, 214 oxidative stress, 1269 inflammatory genes. After STRING PPIN analysis, 404 APP, 109 MAPT, 204 oxidative stress and 1014 inflammation related high confidence proteins were identified. The overlap among all datasets yielded eight common markers (AKT1, GSK3B, APP, APOE, EGFR, PIN1, CASP8 and SNCA). These genes showed association with hepatitis C virus (HCV), Epstein- Barr virus (EBV), human herpes virus 8 and Human papillomavirus (HPV). Further, screening of drugs targeting candidate genes, and possessing anti-inflammatory property, antiviral activity along with a suggested role in AD pathophysiology yielded 12 potential drug candidates. Our study demonstrated the role of viral etiology in AD pathogenesis by elucidating interaction of oxidative stress and inflammation causing candidate genes with common viruses along with the identification of potential AD drug candidates.
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Affiliation(s)
- Puneet Talwar
- Genomics and Molecular Medicine Unit, Institute of Genomics and Integrative Biology (IGIB), Council of Scientific and Industrial Research (CSIR), Delhi, India
| | - Renu Gupta
- Institute of Human Behaviour & Allied Sciences (IHBAS), Dilshad Garden, Delhi 110 095, India
| | - Suman Kushwaha
- Institute of Human Behaviour & Allied Sciences (IHBAS), Dilshad Garden, Delhi 110 095, India
| | - Rachna Agarwal
- Institute of Human Behaviour & Allied Sciences (IHBAS), Dilshad Garden, Delhi 110 095, India
| | - Luciano Saso
- Department of Physiology and Pharmacology, Sapienza University of Rome, Italy
| | | | - Ritushree Kukreti
- Genomics and Molecular Medicine Unit, Institute of Genomics and Integrative Biology (IGIB), Council of Scientific and Industrial Research (CSIR), Delhi, India
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Mondal P, Das G, Khan J, Pradhan K, Mallesh R, Saha A, Jana B, Ghosh S. Potential Neuroprotective Peptide Emerged from Dual Neurotherapeutic Targets: A Fusion Approach for the Development of Anti-Alzheimer's Lead. ACS Chem Neurosci 2019; 10:2609-2620. [PMID: 30840820 DOI: 10.1021/acschemneuro.9b00115] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Amyloid-beta (Aβ) peptide misfolds into fibrillary aggregates (β-sheet) and is deposited as amyloid plaques in the cellular environment, which severely damages intraneuronal connections leading to Alzheimer's disease (AD) pathogenesis. Furthermore, neurons are rich in tubulin/microtubules, and the intracellular network of microtubules also gets disrupted by the accumulation of Aβ fiber in the brain. Hence, development of new potent molecules, which can simultaneously inhibit Aβ fibrillations and stabilize microtubules, is particularly needed for the efficient therapeutic application in AD. To address these issues, here we introduced an innovative fusion strategy to design and develop next generation anti-AD therapeutic leads. This unexplored fusion strategy entails design and development of a potent nonapeptide by taking into account both the hydrophobic core (17-21) of Aβ peptide and the taxol binding region of β-tubulin. In vitro results suggest that this newly designed peptide interacts at the taxol binding region of β-tubulin with a moderate binding affinity and promotes microtubule polymerization. It has the ability to bind at the hydrophobic core (17-21) of Aβ, responsible for its aggregation, and prevent amyloid fibril as well as plaque formation. In addition, it interacts at the CAS site (catalytic anionic site) of acetylcholinesterase (AChE) and significantly inhibits AChE induced Aβ fibrillation, stimulates neurite branching, and provides stability to intracellular microtubules and extensive protection of neurons against nerve growth factor (NGF) deprived neuron toxicity. Moreover, this newly designed peptide shows good stability in serum obtained from humans and efficiently permeates the blood-brain barrier (BBB) without showing any toxicity toward differentiated PC12 neurons as well as primary rat cortical neurons. This excellent feature of protecting the neurons by stabilizing the microtubules without showing any toxicity toward neurons will make this peptide a potent therapeutic agent of AD in the near future.
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Affiliation(s)
- Prasenjit Mondal
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Gaurav Das
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Juhee Khan
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Krishnangsu Pradhan
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Rathnam Mallesh
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
- National Institute of Pharmaceutical Education and Research, Kolkata, CSIR-Indian Institute of Chemical Biology Campus, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Abhijit Saha
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Batakrishna Jana
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
| | - Surajit Ghosh
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
- National Institute of Pharmaceutical Education and Research, Kolkata, CSIR-Indian Institute of Chemical Biology Campus, 4, Raja S. C. Mullick Road, Jadavpur, Kol-32, West Bengal, India
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9
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Mondal P, Das G, Khan J, Pradhan K, Ghosh S. Crafting of Neuroprotective Octapeptide from Taxol-Binding Pocket of β-Tubulin. ACS Chem Neurosci 2018; 9:615-625. [PMID: 29155559 DOI: 10.1021/acschemneuro.7b00457] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Microtubules play a crucial role in maintaining the shape and function of neurons. During progression of Alzheimer's disease (AD), severe destabilization of microtubules occurs, which leads to the permanent disruption of signal transduction processes and memory loss. Thus, microtubule stabilization is one of the key requirements for the treatment of AD. Taxol, a microtubule stabilizing anticancer drug, has been considered as a potential anti-AD drug but was never tested in AD patients, likely because of its' toxic nature and poor brain exposure. However, other microtubule-targeting agents such as epothilone D (BMS-241027) and TPI-287 (abeotaxane) and NAP peptide (davunetide) have entered in AD clinical programs. Therefore, the taxol binding pocket of tubulin could be a potential site for designing of mild and noncytotoxic microtubule stabilizing molecules. Here, we adopted an innovative strategy for the development of a peptide based microtubule stabilizer, considering the taxol binding pocket of β-tubulin, by using alanine scanning mutagenesis technique. This approach lead us to a potential octapeptide, which strongly binds to the taxol pocket of β-tubulin, serves as an excellent microtubule stabilizer, increases the expression of acetylated tubulin, and acts as an Aβ aggregation inhibitor and neuroprotective agent. Further, results revealed that this peptide is nontoxic against both PC12 derived neurons and primary cortical neurons. We believe that our strategy and discovery of peptide-based microtubule stabilizer will open the door for the development of potential anti-AD therapeutics in near future.
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Affiliation(s)
- Prasenjit Mondal
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032 West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4 Raja S. C. Mullick Road, Kolkata 700032, India
| | - Gaurav Das
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032 West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4 Raja S. C. Mullick Road, Kolkata 700032, India
| | - Juhee Khan
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032 West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4 Raja S. C. Mullick Road, Kolkata 700032, India
| | - Krishnangsu Pradhan
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032 West Bengal, India
| | - Surajit Ghosh
- Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032 West Bengal, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Chemical Biology Campus, 4 Raja S. C. Mullick Road, Kolkata 700032, India
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10
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Penazzi L, Bakota L, Brandt R. Microtubule Dynamics in Neuronal Development, Plasticity, and Neurodegeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 321:89-169. [PMID: 26811287 DOI: 10.1016/bs.ircmb.2015.09.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neurons are the basic information-processing units of the nervous system. In fulfilling their task, they establish a structural polarity with an axon that can be over a meter long and dendrites with a complex arbor, which can harbor ten-thousands of spines. Microtubules and their associated proteins play important roles during the development of neuronal morphology, the plasticity of neurons, and neurodegenerative processes. They are dynamic structures, which can quickly adapt to changes in the environment and establish a structural scaffold with high local variations in composition and stability. This review presents a comprehensive overview about the role of microtubules and their dynamic behavior during the formation and maturation of processes and spines in the healthy brain, during aging and under neurodegenerative conditions. The review ends with a discussion of microtubule-targeted therapies as a perspective for the supportive treatment of neurodegenerative disorders.
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Affiliation(s)
- Lorène Penazzi
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
| | - Lidia Bakota
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
| | - Roland Brandt
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
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11
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Atarod D, Eskandari-Sedighi G, Pazhoohi F, Karimian SM, Khajeloo M, Riazi GH. Microtubule Dynamicity Is More Important than Stability in Memory Formation: an In Vivo Study. J Mol Neurosci 2015; 56:313-9. [DOI: 10.1007/s12031-015-0535-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 02/23/2015] [Indexed: 12/31/2022]
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12
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Erez H, Shemesh OA, Spira ME. Rescue of tau-induced synaptic transmission pathology by paclitaxel. Front Cell Neurosci 2014; 8:34. [PMID: 24574970 PMCID: PMC3918585 DOI: 10.3389/fncel.2014.00034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 01/23/2014] [Indexed: 12/30/2022] Open
Abstract
Behavioral and electrophysiological studies of Alzheimer’s disease (AD) and other tauopathies have revealed that the onset of cognitive decline correlates better with synaptic dysfunctions than with hallmark pathologies such as extracellular amyloid-β plaques, intracellular hyperphosphorylated tau or neuronal loss. Recent experiments have also demonstrated that anti-cancer microtubule (MT)-stabilizing drugs can rescue tau-induced behavioral decline and hallmark neuron pathologies. Nevertheless, the mechanisms underlying tau-induced synaptic dysfunction as well as those involved in the rescue of cognitive decline by MTs-stabilizing drugs remain unclear. Here we began to study these mechanisms using the glutaminergic sensory-motoneuron synapse derived from Aplysia ganglia, electrophysiological methods, the expression of mutant-human tau (mt-htau) either pre or postsynaptically and the antimitotic drug paclitaxel. Expression of mt-htau in the presynaptic neurons led to reduced excitatory postsynaptic potential (EPSP) amplitude generated by rested synapses within 3 days of mt-htau expression, and to deeper levels of homosynaptic depression. mt-htau-induced synaptic weakening correlated with reduced releasable presynaptic vesicle pools as revealed by the induction of asynchronous neurotransmitter release by hypertonic sucrose solution. Paclitaxel totally rescued tau-induced synaptic weakening by maintaining the availability of the presynaptic vesicle stores. Postsynaptic expression of mt-htau did not impair the above described synaptic-transmission parameters for up to 5 days. Along with earlier confocal microscope observations from our laboratory, these findings suggest that tau-induced synaptic dysfunction is the outcome of impaired axoplasmic transport and the ensuing reduction in the releasable presynaptic vesicle stores rather than the direct effects of mt-htau or paclitaxel on the synaptic release mechanisms.
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Affiliation(s)
- Hadas Erez
- Department of Neurobiology, The Life Sciences Institute, The Hebrew University of Jerusalem Jerusalem, Israel
| | - Or A Shemesh
- Department of Neurobiology, The Life Sciences Institute, The Hebrew University of Jerusalem Jerusalem, Israel
| | - Micha E Spira
- Department of Neurobiology, The Life Sciences Institute, The Hebrew University of Jerusalem Jerusalem, Israel
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13
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Pianu B, Lefort R, Thuiliere L, Tabourier E, Bartolini F. The Aβ₁₋₄₂ peptide regulates microtubule stability independently of tau. J Cell Sci 2014; 127:1117-27. [PMID: 24424028 DOI: 10.1242/jcs.143750] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Interference with microtubule stability by beta-amyloid peptide (Aβ) has been shown to disrupt dendritic function and axonal trafficking, both early events in Alzheimer's disease. However, it is unclear whether Aβ regulation of microtubule dynamics can occur independently of its action on tau. RhoA has been implicated in neurotoxicity by Aβ but the mechanism by which this activation generates cytoskeletal changes is also unclear. We found that oligomeric Aβ1-42 induced the formation of stable detyrosinated microtubules in NIH3T3 cells and this function resulted from the activation of a RhoA-dependent microtubule stabilization pathway regulated by integrin signaling and the formin mDia1. Induction of microtubule stability by Aβ was also initiated by dimerization of APP and required caspase activity, two previously characterized regulators of neurotoxicity downstream of Aβ. Finally, we found that this function was conserved in primary neurons and abolished by Rho inactivation, reinforcing a link between induction of stable detyrosinated microtubules and neuropathogenesis by Aβ. Our study reveals a novel activity of Aβ on the microtubule cytoskeleton that is independent of tau and associated with pathways linked to microtubule stabilization and Aβ-mediated neurotoxicity.
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Affiliation(s)
- Barbara Pianu
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
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14
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Ballatore C, Brunden KR, Huryn DM, Trojanowski JQ, Lee VMY, Smith AB. Microtubule stabilizing agents as potential treatment for Alzheimer's disease and related neurodegenerative tauopathies. J Med Chem 2012; 55:8979-96. [PMID: 23020671 PMCID: PMC3493881 DOI: 10.1021/jm301079z] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The microtubule (MT) associated protein tau, which is highly expressed in the axons of neurons, is an endogenous MT-stabilizing agent that plays an important role in axonal transport. Loss of MT-stabilizing tau function, caused by misfolding, hyperphosphorylation, and sequestration of tau into insoluble aggregates, leads to axonal transport deficits with neuropathological consequences. Several in vitro and preclinical in vivo studies have shown that MT-stabilizing drugs can be utilized to compensate for the loss of tau function and to maintain/restore effective axonal transport. These findings indicate that MT-stabilizing compounds hold considerable promise for the treatment of Alzheimer disease and related tauopathies. The present article provides a synopsis of the key findings demonstrating the therapeutic potential of MT-stabilizing drugs in the context of neurodegenerative tauopathies, as well as an overview of the different classes of MT-stabilizing compounds.
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Affiliation(s)
- Carlo Ballatore
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, 231 South 34 St., Philadelphia, PA 19104-6323
- Center for Neurodegenerative Diseases Research and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104-6323
| | - Kurt R. Brunden
- Center for Neurodegenerative Diseases Research and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104-6323
| | - Donna M. Huryn
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, 231 South 34 St., Philadelphia, PA 19104-6323
| | - John Q. Trojanowski
- Center for Neurodegenerative Diseases Research and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104-6323
| | - Virginia M.-Y. Lee
- Center for Neurodegenerative Diseases Research and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104-6323
| | - Amos B. Smith
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, 231 South 34 St., Philadelphia, PA 19104-6323
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15
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Fujiwara T, Morimoto K. Cooperative effect of p150Glued and microtubule stabilization to suppress excitotoxicity-induced axon degeneration. Biochem Biophys Res Commun 2012; 424:82-8. [PMID: 22728878 DOI: 10.1016/j.bbrc.2012.06.071] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Accepted: 06/18/2012] [Indexed: 10/28/2022]
Abstract
Glutamate excitotoxicity is implicated in chronic neurological disorders and acute CNS insults and causes neuronal degeneration including axons. The molecular mechanism underlying excitotoxicity-induced axon degeneration is poorly understood. Recently, we found that components of the dynein-dynactin complex that governs microtubule-dependent retrograde transport play important roles in modulating the process of excitotoxicity-induced neurodegeneration. Here we used hippocampal cultures and searched for pathways that function in concert with the components of the dynein-dynactin complex and identified microtubule stabilization as a cooperative pathway to suppress axon degeneration. We find that overexpression of p150Glued, a major component of the dynactin complex, and microtubule stabilization cooperatively suppress axon degeneration. The protective effect of p150Glued is dependent on the C-terminal region as excitotoxicity-induced C-terminal truncated form of p150Glued was unable to interact with APP cargo and altered the localization of APP in neurites when overexpressed. C-terminal truncation of p150Glued is not rescued by microtubule stabilization suggesting that the downstream effects of p150Glued and microtubule stabilization to protect axon degeneration are mutually exclusive.
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Affiliation(s)
- Takeshi Fujiwara
- Department of Biochemistry and Molecular Biology, Osaka University Graduate School of Medicine, Osaka, Japan.
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16
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Kumar S, Okello EJ, Harris JR. Experimental inhibition of fibrillogenesis and neurotoxicity by amyloid-beta (Aβ) and other disease-related peptides/proteins by plant extracts and herbal compounds. Subcell Biochem 2012; 65:295-326. [PMID: 23225009 DOI: 10.1007/978-94-007-5416-4_13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Amyloid-β (Aβ) fibrillogenesis and associated cyto/neurotoxicity are major pathological events and hallmarks in diseases such as Alzheimer's disease (AD). The understanding of Aβ molecular pathogenesis is currently a pharmacological target for rational drug design and discovery based on reduction of Aβ generation, inhibition of Aβ fibrillogenesis and aggregation, enhancement of Aβ clearance and amelioration of associated cytotoxicity. Molecular mechanisms for other amyloidoses, such as transthyretin amyloidosis, AL-amyloidosis, as well as α-synuclein and prion protein are also pharmacological targets for current drug therapy, design and discovery. We report on natural herbal compounds and extracts that are capable binding to and inhibiting different targets associated with AD and other amyloid-associated diseases, providing a basis for future therapeutic strategies. Many herbal compounds, including curcumin, galantamine, quercetin and other polyphenols, are under active investigation and hold considerable potential for future prophylactic and therapeutic treatment against AD and other neurodegenerative diseases, as well as systemic amyloid diseases. A common emerging theme throughout many studies is the anti-oxidant and anti-inflammatory properties of the compounds or herbal extracts under investigation, within the context of the inhibition of cyto/neurotoxicity and anti-amyloid activity.
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Affiliation(s)
- Suresh Kumar
- University School of Biotechnology, GGS Indraprastha University, Sector 16C, 10075, Dwarka, Delhi, India,
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17
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Qi SH, Zhao H, Gong JJ, Sun FM, Yue J, Guan QH, Wang M. Neuroprotection of paclitaxel against cerebral ischemia/reperfusion-induced brain injury through JNK3 signaling pathway. J Recept Signal Transduct Res 2011; 31:402-7. [PMID: 22060185 DOI: 10.3109/10799893.2011.621070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this study, we investigated the neuroprotective effects of paclitaxel in transient cerebral ischemia and possible regulatory mechanism of these neuroprotection. Our data showed that paclitaxel can down-regulate the increased MLK3, JNK3, c-Jun, Bcl-2, and caspase-3 phosphorylation induced by ischemia injury. Cresyl violet staining and immunohistochemistry results demonstrated that paclitaxel had neuroprotective effect against ischemia/reperfusion-induced neuronal cell death. These results indicated that paclitaxel has neuroprotection in ischemic injury through JNK3 signaling pathway and provided a novel possible drug in therapeutics of brain ischemia.
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Affiliation(s)
- Su-Hua Qi
- Research Center for Biochemistry and Molecular Biology and Provincial Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical College , Xuzhou, P. R. China.
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18
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Rescue of neurons from undergoing hallmark tau-induced Alzheimer's disease cell pathologies by the antimitotic drug paclitaxel. Neurobiol Dis 2011; 43:163-75. [DOI: 10.1016/j.nbd.2011.03.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/14/2011] [Accepted: 03/06/2011] [Indexed: 11/18/2022] Open
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19
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Couturier J, Paccalin M, Morel M, Terro F, Milin S, Pontcharraud R, Fauconneau B, Page G. Prevention of the β-amyloid peptide-induced inflammatory process by inhibition of double-stranded RNA-dependent protein kinase in primary murine mixed co-cultures. J Neuroinflammation 2011; 8:72. [PMID: 21699726 PMCID: PMC3131234 DOI: 10.1186/1742-2094-8-72] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Accepted: 06/23/2011] [Indexed: 12/28/2022] Open
Abstract
Background Inflammation may be involved in the pathogenesis of Alzheimer's disease (AD). There has been little success with anti-inflammatory drugs in AD, while the promise of anti-inflammatory treatment is more evident in experimental models. A new anti-inflammatory strategy requires a better understanding of molecular mechanisms. Among the plethora of signaling pathways activated by β-amyloid (Aβ) peptides, the nuclear factor-kappa B (NF-κB) pathway could be an interesting target. In virus-infected cells, double-stranded RNA-dependent protein kinase (PKR) controls the NF-κB signaling pathway. It is well-known that PKR is activated in AD. This led us to study the effect of a specific inhibitor of PKR on the Aβ42-induced inflammatory response in primary mixed murine co-cultures, allowing interactions between neurons, astrocytes and microglia. Methods Primary mixed murine co-cultures were prepared in three steps: a primary culture of astrocytes and microglia for 14 days, then a primary culture of neurons and astrocytes which were cultured with microglia purified from the first culture. Before exposure to Aβ neurotoxicity (72 h), co-cultures were treated with compound C16, a specific inhibitor of PKR. Levels of tumor necrosis factor-α (TNFα), interleukin (IL)-1β, and IL-6 were assessed by ELISA. Levels of PT451-PKR and activation of IκB, NF-κB and caspase-3 were assessed by western blotting. Apoptosis was also followed using annexin V-FITC immunostaining kit. Subcellular distribution of PT451-PKR was assessed by confocal immunofluorescence and morphological structure of cells by scanning electron microscopy. Data were analysed using one-way ANOVA followed by a Newman-Keuls' post hoc test Results In these co-cultures, PKR inhibition prevented Aβ42-induced activation of IκB and NF-κB, strongly decreased production and release of tumor necrosis factor (TNFα) and interleukin (IL)-1β, and limited apoptosis. Conclusion In spite of the complexity of the innate immune response, PKR inhibition could be an interesting anti-inflammatory strategy in AD.
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Affiliation(s)
- J Couturier
- Research Group on Brain Aging, GReViC EA 3808, 6 rue de la Milétrie BP 199, 86034 Poitiers Cedex, France
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20
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Kumar S, Seal CJ, Howes MJR, Kite GC, Okello EJ. In vitro protective effects of Withania somnifera (L.) dunal root extract against hydrogen peroxide and β-amyloid(1-42)-induced cytotoxicity in differentiated PC12 cells. Phytother Res 2011; 24:1567-74. [PMID: 20680931 DOI: 10.1002/ptr.3261] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Withania somnifera L. Dunal (Solanaceae), also known as 'ashwagandha' in Sanskrit and as 'Indian ginseng', is used widely in Ayurvedic medicine as a nerve tonic and memory enhancer, with antiaging, antistress, immunomodulatory and antioxidant properties. There is a paucity of data on the potential neuroprotective effects of W. somnifera root, as traditionally used, against H(2)O(2)- and Aβ((1-42))-induced cytotoxicity which are current targets for novel approaches to treat dementia, especially dementia of the Alzheimer's type (AD). In this study, an aqueous extract prepared from the dried roots of W. somnifera was assessed for potential protective effects against H(2)O(2)- and Aβ((1-42))-aggregated fibril cytotoxicity by an MTT assay using a differentiated rat pheochromocytoma PC12 cell line. The results suggest that pretreatments of differentiated PC12 cells with aqueous extracts of W. somnifera root significantly protect differentiated PC12 cells against both H(2)O(2)- and Aβ((1-42))-induced cytotoxicity, in a concentration dependent manner. To investigate the compounds that could explain the observed effects, the W. somnifera extract was analysed by liquid chromatography-serial mass spectrometry and numerous withanolide derivatives, including withaferin A, were detected. These results demonstrate the neuroprotective properties of an aqueous extract of W. somnifera root and may provide some explanation for the putative ethnopharmacological uses of W. somnifera for cognitive and other neurodegenerative disorders that are associated with oxidative stress.
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Affiliation(s)
- S Kumar
- Medicinal Plant Research Group, School of Agriculture, Food and Rural Development, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
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21
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Henriques AG, Vieira SI, da Cruz E Silva EF, da Cruz E Silva OAB. Abeta promotes Alzheimer's disease-like cytoskeleton abnormalities with consequences to APP processing in neurons. J Neurochem 2010; 113:761-71. [PMID: 20345756 DOI: 10.1111/j.1471-4159.2010.06643.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abeta is proteolytically produced from the Alzheimer's amyloid precursor protein (APP). Major properties attributed to Abeta include neurotoxic effects that contribute to Alzheimer's disease neurodegeneration. However, Abeta can also affect APP processing and trafficking that, in neurons, is anterogradelly transported via microtubules in a kinesin-associated manner. Herein we show that Abeta can induce accumulation of intracellular sAPP in primary neuronal cultures. Subcellular fractionation studies and immunofluorescence analysis revealed that upon Abeta exposure sAPP retention was localized to cytoskeleton associated vesicular structures along the neurite processes, positive for an APP N-terminal antibody and negative for an APP C-terminal antibody. These vesicular structures were also positive for kinesin light chain 1 (KLC). We confirm that Abeta alters both actin and microtubule networks. It increases F-actin polymerization and we report for the first time that Abeta decreases alpha-tubulin acetylation. The use of cytoskeleton associated drugs partially reversed the Abeta-induced effects on sAPP secretion. The data here presented show that Abeta causes intracellular sAPP retention by inducing alterations in the cytoskeleton network, thus contributing to impaired APP/sAPP vesicular transport. Moreover, the data strengthens the hypothesis that Abeta-induces neurodegeneration and provides a potential mechanism of action, as impaired vesicular and axonal transport have been linked to Alzheimer's disease pathology.
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Affiliation(s)
- Ana Gabriela Henriques
- Laboratório de Neurociências, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
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22
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Desino KE, Ansar S, Georg GI, Himes RH, Michaelis ML, Powell DR, Reiff EA, Telikepalli H, Audus KL. (3R,5S,7as)-(3,5-Bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol, a novel neuroprotective agent. J Med Chem 2009; 52:7537-43. [PMID: 19728715 PMCID: PMC2788673 DOI: 10.1021/jm900254k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Compounds that interact with microtubules, such as paclitaxel, have been shown to possess protective properties against beta-amyloid (Abeta) induced neurodegeneration associated with Alzheimer's disease. In this work, the novel agent (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol was investigated for effectiveness in protecting neurons against several toxic stimuli and its interaction with the microtubule network. Exposure of neuronal cultures to Abeta peptide in the presence of 5 nM (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol resulted in a 50% increase in survival. Neuronal cultures treated with other toxic stimuli such as staurosporine, thapsigargin, paraquat, and H(2)O(2) showed significantly enhanced survival in the presence of (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol. Microtubule binding and tubulin assembly studies revealed differences compared to paclitaxel but confirmed the interaction of (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol with microtubules. Furthermore, in vitro studies using bovine brain microvessel endothelial cells experiments suggest that (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol can readily cross the blood-brain barrier in a passive manner.
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Affiliation(s)
- Kelly E. Desino
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, Kansas 66047
| | - Sabah Ansar
- Department of Pharmacology and Toxicology, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045
| | - Gunda I. Georg
- Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045
| | - Richard H. Himes
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas 66045
| | - Mary Lou Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045
| | - Douglas R. Powell
- X-Ray Crystallography Laboratory, The University of Kansas, 1251 Wescoe Hall Drive Lawrence, Kansas 66045
| | - Emily A. Reiff
- Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045
| | - Hanumaiah Telikepalli
- Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045
| | - Kenneth L. Audus
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, Kansas 66047
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Zaidi A, Fernandes D, Bean JL, Michaelis ML. Effects of paraquat-induced oxidative stress on the neuronal plasma membrane Ca(2+)-ATPase. Free Radic Biol Med 2009; 47:1507-14. [PMID: 19715754 PMCID: PMC2789485 DOI: 10.1016/j.freeradbiomed.2009.08.018] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 08/17/2009] [Accepted: 08/20/2009] [Indexed: 12/25/2022]
Abstract
Oxidative stress leads to the disruption of calcium homeostasis in brain neurons; however, the direct effects of oxidants on proteins that regulate intracellular calcium ([Ca(2+)](i)) are not known. The calmodulin (CaM)-stimulated plasma membrane Ca(2+)-ATPase (PMCA) plays a critical role in regulating [Ca(2+)](i). Our previous in vitro studies showed that PMCA present in brain synaptic membranes is readily inactivated by a variety of reactive oxygen species (ROS). The present studies were conducted to determine the vulnerability of PMCA to ROS generated in neurons as would probably occur in vivo. Primary cortical neurons were exposed to paraquat (PQ), a redox cycling agent that generates intracellular ROS. Low concentrations of PQ (5-10 microM) increased PMCA basal activity by two-fold but abolished its sensitivity to CaM. Higher concentrations (25-100 microM) inhibited both components of PMCA activity. Immunoblots showed the formation of high-molecular-weight PMCA aggregates. Additionally, PMCA showed evidence of proteolytic degradation. PMCA proteolysis was prevented by a calpain inhibitor, suggesting a role for calpain. Our findings suggest that PMCA is a sensitive target of oxidative stress in primary neurons. Inactivation of this Ca(2+) transporter under prolonged oxidative stress could alter neuronal Ca(2+) signaling.
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Affiliation(s)
- Asma Zaidi
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS 66045, USA.
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24
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Folwell J, Cowan CM, Ubhi KK, Shiabh H, Newman TA, Shepherd D, Mudher A. Abeta exacerbates the neuronal dysfunction caused by human tau expression in a Drosophila model of Alzheimer's disease. Exp Neurol 2009; 223:401-9. [PMID: 19782075 DOI: 10.1016/j.expneurol.2009.09.014] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 09/11/2009] [Accepted: 09/17/2009] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease (AD) is characterised by neurofibrillary tangles composed of hyper-phosphorylated tau, and neuritic plaques composed of misfolded amyloid peptide (Abeta(42)). It is generally believed that the hyper-phosphorylated tau and oligomeric Abeta(42) are responsible for the neuronal dysfunction and cognitive impairments that underlie the early stages of AD, but the mechanism by which they interact in the pathogenic process is not clear. Mounting evidence suggests that Abeta(42) pathology lies upstream of hyper-phosphorylated tau pathology. Similarly much is being learnt about how each protein affects neuronal function. However, the impact that either pathological protein has on neuronal dysfunction caused by the other is not extensively studied. We have investigated this in a Drosophila model of AD in which we express both phosphorylated human tau (tau(wt)) and oligomeric Abeta(42). We find that expression of tau(wt) causes neuronal dysfunction by disrupting axonal transport and synaptic structure, and that this leads to behavioural impairments and reduced lifespan. Co-expression of Abeta(42) with tau(wt) increases tau phosphorylation and exacerbates all these tau-mediated phenotypes. Treatment of tau(wt)/Abeta(42) and flies with LiCl ameliorates the exacerbating effect of Abeta(42), suggesting that GSK-3beta may be involved in the mechanism by which Abeta(42) and tau(wt) interact to cause neuronal dysfunction. Conversely to the effect of Abeta(42), mimicking the wingless signalling pathway by co-expression of dishevelled with tau(wt) reduces tau phosphorylation and suppresses the tau-mediated phenotypes. It is therefore possible to speculate that the mechanism by which Abeta(42) interacts with tau in the pathogenesis of AD is by down-regulating endogenous wnt signalling.
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Affiliation(s)
- James Folwell
- Department of Neurosciences, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK
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25
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Desino KE, Pignatello R, Guccione S, Basile L, Ansar S, Michaelis ML, Ramsay RR, Audus KL. TCP-FA4: a derivative of tranylcypromine showing improved blood-brain permeability. Biochem Pharmacol 2009; 78:1412-7. [PMID: 19679106 DOI: 10.1016/j.bcp.2009.07.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 07/31/2009] [Accepted: 07/31/2009] [Indexed: 11/25/2022]
Abstract
A variety of approaches have been taken to improve the brain penetration of pharmaceutical agents. The amphipathic character of a compound can improve its interaction with the lipid bilayer within cell membranes, and as a result improve permeability. Fatty acid chains or lipoamino acids of various lengths were attached to tranylcypromine (TCP), in an attempt to improve the blood-brain barrier (BBB) permeability by increasing the lipophilicity as well as the amphiphatic character of the drug. TCP-FA4, one of the derivatives containing a four carbon alkyl acid chain, showed the greatest improvement in permeability. This molecule was slightly neuroprotective in a beta-amyloid-induced neurodegeneration assay and may also be capable of upregulating brain derived neurotrophic factor (BDNF), as indicated by cell culture assays using human umbilical vein endothelial cells. Since decreased levels of BDNF are observed in many CNS disorders, and direct injection of BDNF is not a viable option due to its poor permeability across the BBB, small molecules capable of regulating BDNF that also cross the BBB may be an interesting treatment option.
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Affiliation(s)
- Kelly E Desino
- The University of Kansas, Department of Pharmaceutical Chemistry, 2095 Constant Ave, Lawrence, KS 66047, USA.
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Genomic and biochemical approaches in the discovery of mechanisms for selective neuronal vulnerability to oxidative stress. BMC Neurosci 2009; 10:12. [PMID: 19228403 PMCID: PMC2677396 DOI: 10.1186/1471-2202-10-12] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Accepted: 02/19/2009] [Indexed: 12/12/2022] Open
Abstract
Background Oxidative stress (OS) is an important factor in brain aging and neurodegenerative diseases. Certain neurons in different brain regions exhibit selective vulnerability to OS. Currently little is known about the underlying mechanisms of this selective neuronal vulnerability. The purpose of this study was to identify endogenous factors that predispose vulnerable neurons to OS by employing genomic and biochemical approaches. Results In this report, using in vitro neuronal cultures, ex vivo organotypic brain slice cultures and acute brain slice preparations, we established that cerebellar granule (CbG) and hippocampal CA1 neurons were significantly more sensitive to OS (induced by paraquat) than cerebral cortical and hippocampal CA3 neurons. To probe for intrinsic differences between in vivo vulnerable (CA1 and CbG) and resistant (CA3 and cerebral cortex) neurons under basal conditions, these neurons were collected by laser capture microdissection from freshly excised brain sections (no OS treatment), and then subjected to oligonucleotide microarray analysis. GeneChip-based transcriptomic analyses revealed that vulnerable neurons had higher expression of genes related to stress and immune response, and lower expression of energy generation and signal transduction genes in comparison with resistant neurons. Subsequent targeted biochemical analyses confirmed the lower energy levels (in the form of ATP) in primary CbG neurons compared with cortical neurons. Conclusion Low energy reserves and high intrinsic stress levels are two underlying factors for neuronal selective vulnerability to OS. These mechanisms can be targeted in the future for the protection of vulnerable neurons.
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Limpeanchob N, Jaipan S, Rattanakaruna S, Phrompittayarat W, Ingkaninan K. Neuroprotective effect of Bacopa monnieri on beta-amyloid-induced cell death in primary cortical culture. JOURNAL OF ETHNOPHARMACOLOGY 2008; 120:112-117. [PMID: 18755259 DOI: 10.1016/j.jep.2008.07.039] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 07/09/2008] [Accepted: 07/28/2008] [Indexed: 05/26/2023]
Abstract
AIM OF THE STUDY Bacopa monnieri (Brahmi) is extensively used in traditional Indian medicine as a nerve tonic and thought to improve memory. To examine the neuroprotective effects of Brahmi extract, we tested its protection against the beta-amyloid protein (25-35) and glutamate-induced neurotoxicity in primary cortical cultured neurons. MATERIALS AND METHODS Neuroprotective effects were determined by measuring neuronal cell viability following beta-amyloid and glutamate treatment with and without Brahmi extract. Mechanisms of neuroprotection were evaluated by monitoring cellular oxidative stress and acetylcholinesterase activity. RESULTS Our result demonstrated that Brahmi extract protected neurons from beta-amyloid-induced cell death, but not glutamate-induced excitotoxicity. This neuroprotection was possibly due to its ability to suppress cellular acetylcholinesterase activity but not the inhibition of glutamate-mediated toxicity. In addition, culture medium containing Brahmi extract appeared to promote cell survival compared to neuronal cells growing in regular culture medium. Further study showed that Brahmi-treated neurons expressed lower level of reactive oxygen species suggesting that Brahmi restrained intracellular oxidative stress which in turn prolonged the lifespan of the culture neurons. Brahmi extract also exhibited both reducing and lipid peroxidation inhibitory activities. CONCLUSIONS From this study, the mode of action of neuroprotective effects of Brahmi appeared to be the results of its antioxidant to suppress neuronal oxidative stress and the acetylcholinesterase inhibitory activities. Therefore, treating patients with Brahmi extract may be an alternative direction for ameliorating neurodegenerative disorders associated with the overwhelming oxidative stress as well as Alzheimer's disease.
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Affiliation(s)
- Nanteetip Limpeanchob
- Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand.
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Turunen BJ, Ge H, Oyetunji J, Desino KE, Vasandani V, Güthe S, Himes RH, Audus KL, Seelig A, Georg GI. Paclitaxel succinate analogs: Anionic and amide introduction as a strategy to impart blood-brain barrier permeability. Bioorg Med Chem Lett 2008; 18:5971-4. [PMID: 18926701 DOI: 10.1016/j.bmcl.2008.09.103] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 09/19/2008] [Accepted: 09/22/2008] [Indexed: 11/29/2022]
Abstract
A focused library of TX-67 (C10 hemi-succinate) analogs has been prepared, including C7 regioisomers, esters, amides, and one-carbon homologs. These were prepared to investigate whether the lack of TX-67 interaction with P-glycoprotein (Pgp) is due to the presence of the carboxylic acid moiety and whether this phenomenon was restricted to C10 analogs. Tubulin stabilization ability, cytotoxicity, and Pgp interactions were evaluated. All carboxylic acid analogs and several of the amides had no apparent interactions with Pgp at the concentrations used, whereas the ester variants displayed characteristics of Pgp substrates. Furthermore, it was demonstrated that hydrogen-bonding properties were significant with respect to Pgp interactions. Calculations of logD and cross-sectional areas revealed that these analogs are predicted to partition into the membrane and can compete for Pgp binding sites. The anionic and amide introduction strategy may allow for delivery of paclitaxel into the CNS and may be a potential approach for the delivery of other, structurally complex and lipophilic non-CNS permeable drugs.
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Affiliation(s)
- Brandon J Turunen
- Department of Medicinal Chemistry, University of Kansas, Malott Hall 4070, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA
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Smith AB, Freeze BS. (+)-Discodermolide: Total Synthesis, Construction of Novel Analogues, and Biological Evaluation. Tetrahedron 2008; 64:261-298. [PMID: 21113402 DOI: 10.1016/j.tet.2007.10.039] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Amos B Smith
- Department of Chemistry, Monell Chemical Senses Center, Penn Center for Molecular Discovery, and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104
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Jiang L, Fernandes D, Mehta N, Bean JL, Michaelis ML, Zaidi A. Partitioning of the plasma membrane Ca2+-ATPase into lipid rafts in primary neurons: effects of cholesterol depletion. J Neurochem 2007; 102:378-88. [PMID: 17596212 DOI: 10.1111/j.1471-4159.2007.04480.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Spatial and temporal alterations in intracellular calcium [Ca(2+)](i) play a pivotal role in a wide array of neuronal functions. Disruption in Ca(2+) homeostasis has been implicated in the decline in neuronal function in brain aging and in neurodegenerative disorders. The plasma membrane Ca(2+)-ATPase (PMCA) is a high affinity Ca(2+) transporter that plays a crucial role in the termination of [Ca(2+)](i) signals and in the maintenance of low [Ca(2+)](i) essential for signaling. Recent evidence indicates that PMCA is uniquely sensitive to its lipid environment and is stimulated by lipids with ordered acyl chains. Here we show that both PMCA and its activator calmodulin (CaM) are partitioned into liquid-ordered, cholesterol-rich plasma membrane microdomains or 'lipid rafts' in primary cultured neurons. Association of PMCA with rafts was demonstrated in preparations isolated by sucrose density gradient centrifugation and in intact neurons by confocal microscopy. Total raft-associated PMCA activity was much higher than the PMCA activity excluded from these microdomains. Depletion of cellular cholesterol dramatically inhibited the activity of the raft-associated PMCA with no effect on the activity of the non-raft pool. We propose that association of PMCA with rafts represents a novel mechanism for its regulation and, consequently, of Ca(2+) signaling in the central nervous system.
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Affiliation(s)
- Lei Jiang
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, Kansas 66045, USA
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Affiliation(s)
- David W Christianson
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA.
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32
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Seyb KI, Ansar S, Li G, Bean J, Michaelis ML, Dobrowsky RT. p35/Cyclin-dependent kinase 5 is required for protection against beta-amyloid-induced cell death but not tau phosphorylation by ceramide. J Mol Neurosci 2007; 31:23-35. [PMID: 17416967 DOI: 10.1007/bf02686115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 11/30/1999] [Accepted: 06/03/2006] [Indexed: 12/19/2022]
Abstract
Ceramide is a bioactive sphingolipid that can prevent calpain activation and beta-amyloid (A beta) neurotoxicity in cortical neurons. Recent evidence supports A beta induction of a calpain-dependent cleavage of the cyclin-dependent kinase 5 (cdk5) regulatory protein p35 that contributes to tau hyperphosphorylation and neuronal death. Using cortical neurons isolated from wild-type and p35 knockout mice, we investigated whether ceramide required p35/cdk5 to protect against A beta-induced cell death and tau phosphorylation. Ceramide inhibited A beta-induced calpain activation and cdk5 activity in wild-type neurons and protected against neuronal death and tau hyperphosphorylation. Interestingly, A beta also increased cdk5 activity in p35-/- neurons, suggesting that the alternate cdk5 regulatory protein, p39, might mediate this effect. In p35 null neurons, ceramide blocked A beta-induced calpain activation but did not inhibit cdk5 activity or cell death. However, ceramide blocked tau hyperphosphorylation potentially via inhibition of glycogen synthase kinase-3beta. These data suggest that ceramide can regulate A beta cell toxicity in a p35/cdk5-dependent manner.
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Affiliation(s)
- Kathleen I Seyb
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS 66045, USA
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Fernandes D, Zaidi A, Bean J, Hui D, Michaelis ML. RNA--induced silencing of the plasma membrane Ca2+-ATPase 2 in neuronal cells: effects on Ca2+ homeostasis and cell viability. J Neurochem 2007; 102:454-65. [PMID: 17488275 DOI: 10.1111/j.1471-4159.2007.04592.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intraneuronal calcium ([Ca(2+)](i)) regulation is altered in aging brain, possibly because of the changes in critical Ca(2+) transporters. We previously reported that the levels of the plasma membrane Ca(2+)-ATPase (PMCA) and the V(max) for enzyme activity are significantly reduced in synaptic membranes in aging rat brain. The goal of these studies was to use RNA(i) techniques to suppress expression of a major neuronal isoform, PMCA2, in neurons in culture to determine the potential functional consequences of a decrease in PMCA activity. Embryonic rat brain neurons and SH-SY5Y neuroblastoma cells were transfected with in vitro--transcribed short interfering RNA or a short hairpin RNA expressing vector, respectively, leading to 80% suppression of PMCA2 expression within 48 h. Fluorescence ratio imaging of free [Ca(2+)](i) revealed that primary neurons with reduced PMCA2 expression had higher basal [Ca(2+)](i), slower recovery from KCl-induced Ca(2+) transients, and incomplete return to pre-stimulation Ca(2+) levels. Primary neurons and SH-SY5Y cells with PMCA2 suppression both exhibited significantly greater vulnerability to the toxicity of various stresses. Our results indicate that a loss of PMCA such as occurs in aging brain likely leads to subtle disruptions in normal Ca(2+) signaling and enhanced susceptibility to stresses that can alter the regulation of Ca(2+) homeostasis.
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Butler D, Bendiske J, Michaelis ML, Karanian DA, Bahr BA. Microtubule-stabilizing agent prevents protein accumulation-induced loss of synaptic markers. Eur J Pharmacol 2007; 562:20-7. [PMID: 17336290 DOI: 10.1016/j.ejphar.2007.01.053] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 01/15/2007] [Accepted: 01/17/2007] [Indexed: 11/18/2022]
Abstract
Synaptic pathology is associated with protein accumulation events, and is thought by many to be the best correlate of cognitive impairment in normal aging and different types of dementia including Alzheimer's disease. Numerous studies point to the disruption of microtubule-based transport mechanisms as a contributor to synaptic degeneration. Reported reductions in a microtubule stability marker, acetylated alpha-tubulin, suggest that disrupted transport occurs in Alzheimer's disease neurons, and such a reduction is known to be associated with transport failure and synaptic compromise in a hippocampal slice model of protein accumulation. The slice model exhibits accumulated proteins in response to chloroquine-mediated lysosomal dysfunction, resulting in corresponding decreases in acetylated tubulin and pre- and postsynaptic markers (synaptophysin and glutamate receptors). To test whether the protein deposition-induced loss of synaptic proteins is due to disruption of microtubule integrity, a potent microtubule-stabilizing agent, the taxol derivative TX67 (10-succinyl paclitaxel), was applied to the hippocampal slice cultures. In the absence of lysosomal stress, TX67 (100-300 nM) provided microtubule stabilization as indicated by markedly increased levels of acetylated tubulin. When TX67 was applied to the slices during the chloroquine treatment period, pre- and postsynaptic markers were maintained at control levels. In addition, a correlation was evident across slice samples between levels of acetylated tubulin and glutamate receptor subunit GluR1. These data indicate that disruption of microtubule integrity accounts for protein deposition-induced synaptic decline. They also suggest that microtubule-stabilizing drugs can be used to slow or halt the progressive synaptic deterioration linked to Alzheimer-type pathogenesis.
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Affiliation(s)
- David Butler
- Department of Pharmaceutical Sciences and the Neurosciences Program, University of Connecticut, Storrs, CT 06269-3092, USA
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35
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Ansar S, Burlison JA, Hadden MK, Yu XM, Desino KE, Bean J, Neckers L, Audus KL, Michaelis ML, Blagg BSJ. A non-toxic Hsp90 inhibitor protects neurons from Abeta-induced toxicity. Bioorg Med Chem Lett 2007; 17:1984-90. [PMID: 17276679 DOI: 10.1016/j.bmcl.2007.01.017] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Accepted: 01/08/2007] [Indexed: 12/12/2022]
Abstract
The molecular chaperones have been implicated in numerous neurodegenerative disorders in which the defining pathology is misfolded proteins and the accumulation of protein aggregates. In Alzheimer's disease, hyperphosphorylation of tau protein results in its dissociation from microtubules and the formation of pathogenic aggregates. An inverse relationship was demonstrated between Hsp90/Hsp70 levels and aggregated tau, suggesting that Hsp90 inhibitors that upregulate these chaperones could provide neuroprotection. We recently identified a small molecule novobiocin analogue, A4 that induces Hsp90 overexpression at low nanomolar concentrations and sought to test its neuroprotective properties. A4 protected neurons against Abeta-induced toxicity at low nanomolar concentrations that paralleled its ability to upregulate Hsp70 expression. A4 exhibited no cytotoxicity in neuronal cells at the highest concentration tested, 10 microM, thus providing a large therapeutic window for neuroprotection. In addition, A4 was transported across BMECs in vitro, suggesting the compound may permeate the blood-brain barrier in vivo. Taken together, these data establish A4, a C-terminal inhibitor of Hsp90, as a potent lead for the development of a novel class of compounds to treat Alzheimer's disease.
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Affiliation(s)
- Sabah Ansar
- Department of Pharmacology and Toxicology, The University of Kansas, Malott 5064, 1251 Wescoe Hall Drive, Lawrence, KS 66045-7563, USA
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36
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Spletstoser JT, Turunen BJ, Desino K, Rice A, Datta A, Dutta D, Huff JK, Himes RH, Audus KL, Seelig A, Georg GI. Single-site chemical modification at C10 of the baccatin III core of paclitaxel and Taxol C reduces P-glycoprotein interactions in bovine brain microvessel endothelial cells. Bioorg Med Chem Lett 2006; 16:495-8. [PMID: 16289636 DOI: 10.1016/j.bmcl.2005.10.063] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2005] [Revised: 10/18/2005] [Accepted: 10/19/2005] [Indexed: 11/20/2022]
Abstract
A single-site modification of paclitaxel analogs at the C10 position on the baccatin III core that reduces interaction with P-glycoprotein in bovine brain microvessel endothelial cells is described. Modification and derivatization of the C10 position were carried out using a substrate controlled hydride addition to a key C9 and C10 diketone intermediate. The analogs were tested for tubulin assembly and cytotoxicity, and were shown to retain potency similar to paclitaxel. P-glycoprotein interaction was examined using a rhodamine assay and it was found that simple hydrolysis or epimerization of the C10 acetate of paclitaxel and Taxol C can reduce interaction with the P-glycoprotein transporter that may allow for increased permeation of taxanes into the brain.
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Affiliation(s)
- Jared T Spletstoser
- Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA
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Kuret J, Chirita CN, Congdon EE, Kannanayakal T, Li G, Necula M, Yin H, Zhong Q. Pathways of tau fibrillization. Biochim Biophys Acta Mol Basis Dis 2005; 1739:167-78. [PMID: 15615636 DOI: 10.1016/j.bbadis.2004.06.016] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 06/02/2004] [Indexed: 11/22/2022]
Abstract
New methods for analyzing tau fibrillization have yielded insights into the biochemical transitions involved in the process. Here we review the parallels between the sequential progression of tau fibrillization observed macroscopically in Alzheimer's disease (AD) lesions and the pathway of tau aggregation observed in vitro with purified tau preparations. In addition, pharmacological agents for further dissection of fibrillization mechanism and lesion formation are discussed.
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Affiliation(s)
- Jeff Kuret
- Center for Molecular Neurobiology, Department of Molecular and Cellular Biochemistry, Ohio St. University College of Medicine and Public Health, 1060 Carmack Rd., Columbus, OH 43210, USA.
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Castoldi D, Caggiano L, Bayón P, Costa AM, Cappella P, Sharon O, Gennari C. Synthesis of novel, simplified, C-7 substituted eleutheside analogues with potent microtubule-stabilizing activity. Tetrahedron 2005. [DOI: 10.1016/j.tet.2004.12.039] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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39
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Mercado-Gómez O, Ferrera P, Arias C. Histopathologic changes induced by the microtubule-stabilizing agent Taxol in the rat hippocampus in vivo. J Neurosci Res 2004; 78:553-62. [PMID: 15449327 DOI: 10.1002/jnr.20264] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Microtubules and their associated proteins play a prominent role in neuronal morphology, axonal transport, neuronal plasticity, and neuronal degeneration. It has been proposed that microtubule damage is sufficient to induce neuronal death. In this regard, the microtubule-stabilizing agent Taxol could be a useful tool to reproduce some aspects of neurodegenerative diseases associated with disturbances of the cytoskeleton and alterations in axonal transport. Although differential effects of Taxol on neuronal viability have been found in vitro, Taxol toxicity in the central nervous system remains to be addressed. We studied the effects of Taxol on neuronal morphology and viability as well as changes in microtubule-associated proteins MAP2 and tau in rat hippocampus. Our results show that Taxol induces dose-dependent neuronal death accompanied by the loss of MAP2 and the presence of dystrophic neurites. Interestingly paired helical filament (PHF)-1 immunoreactivity, which is associated with a phosphorylated epitope of tau proteins, was induced in the damaged hippocampus. Our results suggest that microtubule dynamics have a role in maintenance of neuronal morphology and survival in vivo, and that modifications in microtubule dynamics, may alter the content and neuronal distribution of MAP2 and promote alterations in the phosphorylation state of tau.
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Affiliation(s)
- Octavio Mercado-Gómez
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México
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40
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Michaelis ML, Ansar S, Chen Y, Reiff ER, Seyb KI, Himes RH, Audus KL, Georg GI. β-Amyloid-Induced Neurodegeneration and Protection by Structurally Diverse Microtubule-Stabilizing Agents. J Pharmacol Exp Ther 2004; 312:659-68. [PMID: 15375176 DOI: 10.1124/jpet.104.074450] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Deposition of beta-amyloid peptide (Abeta) and hyperphosphorylation of the tau protein are associated with neuronal dysfunction and cell death in Alzheimer's disease. Although the relationship between these two processes is not yet understood, studies have shown that both in vitro and in vivo exposure of neurons to Abeta leads to tau hyperphosphorylation and neuronal dystrophy. We previously reported that the microtubule-stabilizing drug paclitaxel (Taxol) protects primary neurons against toxicity induced by the Abeta(25-35) peptide. The studies in this report were undertaken to characterize the actions of paclitaxel more fully, to assess the effectiveness of structurally diverse microtubulestabilizing agents in protecting neurons, and to determine the time course of the protective effects of the drugs. Primary neurons were exposed to Abeta in the presence or absence of several agents shown to interact with microtubules, and neuronal survival was monitored. Paclitaxel protected neurons against Abeta(1-42) toxicity, and paclitaxel-treated cultures exposed to Abeta showed enhanced survival over Abeta-only cultures for several days. Neuronal apoptosis induced by Abeta was blocked by paclitaxel. Other taxanes and three structurally diverse microtubule-stabilizing compounds also significantly increased survival of Abeta-treated cultures. At concentrations below 100 nM, the drugs that protected the neurons did not produce detectable toxicity when added to the cultures alone. Although multiple mechanisms are likely to contribute to the neuronal cell death induced by oligomeric or fibrillar forms of Abeta, low concentrations of drugs that preserve the integrity of the cytoskeletal network may help neurons survive the toxic cascades initiated by these peptides.
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Affiliation(s)
- M L Michaelis
- Department of Pharmacology and Toxicology, 1251 Wescoe Hall Dr., 5064 Malott Hall, University of Kansas, Lawrence, KS 66045, USA.
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Furukawa K, Wang Y, Yao PJ, Fu W, Mattson MP, Itoyama Y, Onodera H, D'Souza I, Poorkaj PH, Bird TD, Schellenberg GD. Alteration in calcium channel properties is responsible for the neurotoxic action of a familial frontotemporal dementia tau mutation. J Neurochem 2003; 87:427-36. [PMID: 14511120 DOI: 10.1046/j.1471-4159.2003.02020.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tau, a microtubule binding protein, is not only a major component of neurofibrillary tangles in Alzheimer's disease, but also a causative gene for hereditary frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). We show here that an FTDP-17 tau mutation (V337M) in SH-SY5Y cells reduces microtubule polymerization, increases voltage-dependent calcium current (ICa) density, and decreases ICa rundown. The reduced rundown of ICa by V337M was significantly inhibited by nifedipine (L-type Ca channel blocker), whereas omega-conotoxin GVIA (N-type Ca channel blocker) showed smaller effects, indicating that tau mutations affect L-type calcium channel activity. The depolarization-induced increase in intracellular calcium was also significantly augmented by the V337M tau mutation. Treatment with a microtubule polymerizing agent (taxol), an adenylyl cyclase inhibitor, or a protein kinase A (PKA) inhibitor, counteracted the effects of mutant tau on ICa. Taxol also attenuated the Ca2+ response to depolarization in cells expressing mutant tau. Apoptosis in SH-SY5Y cells induced by serum deprivation was exacerbated by the V337M mutation, and nifedipine, taxol, and a PKA inhibitor significantly protected cells against apoptosis. Our results indicate that a tau mutation which decreases its microtubule-binding ability augments calcium influx by depolymerizing microtubules and activating adenylyl cyclase and PKA.
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Affiliation(s)
- Katsutoshi Furukawa
- Laboratory of Neurosciences, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA.
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Cytoskeletal and morphological alterations underlying axonal sprouting after localized transection of cortical neuron axons in vitro. J Neurosci 2003. [PMID: 12736342 DOI: 10.1523/jneurosci.23-09-03715.2003] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We examined the cytoskeletal dynamics that characterize neurite sprouting after axonal injury to cortical neurons maintained in culture for several weeks and compared these with initial neurite development. Cultured neocortical neurons, derived from embryonic day 18 rats, were examined at 3 d in vitro (DIV) and at various time points after axotomy at 21 DIV. The postinjury neuritic response was highly dynamic, progressing through an initial phase of retraction, followed by substantial axonal sprouting within 4-6 hr. Postinjury sprouts were motile and slender with expanded growth cone-like end structures. Microtubule markers were localized to sprout shafts and the proximal regions of putative growth cones and filamentous actin was distributed throughout growth cones, whereas neurofilament proteins were restricted to sprout shafts. A similar distribution of cytoskeletal proteins was present in developing neurites at 3 DIV. Exposure of developing and mature, injured cultures to the microtubule stabilizing agent taxol (10 microg/ml) caused growth inhibition, process distension, the transformation of growth cones into bulbous structures, and abnormal neurite directionality. Microtubule and neurofilament segregation occurred after taxol exposure in developing neurites and postinjury sprouts. Exposure to the microtubule destabilizing agent nocodazole (100 microg/ml) resulted in substantial morphological alteration of developing neurons and inhibited neurite growth and postinjury axonal sprouting. Our results indicate that the axons of cortical neurons have an intrinsic ability to sprout after transection, and similar cytoskeletal dynamics underlie neurite development and postinjury axonal sprouting.
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Michaelis ML. Drugs targeting Alzheimer's disease: some things old and some things new. J Pharmacol Exp Ther 2003; 304:897-904. [PMID: 12604663 DOI: 10.1124/jpet.102.035840] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Enormous effort is now being devoted to developing drugs that slow neurodegeneration in Alzheimer's disease (AD), although insights into AD genetics and molecular pathogenesis only arose in the last 15 years. Acetylcholinesterase inhibitors that temporarily slow loss of cognitive function remain the only approved AD drugs. Discovery of mutations in three genes leading to severe early onset AD was critical in focusing attention on the role of amyloid peptides (Abeta) in neuronal cell death, and enhanced understanding of the biology of these peptides has led to an array of mechanism-based drug discovery strategies. These include inhibitors for Abeta-generating proteases, agents that prevent or reverse Abeta oligomerization, immunotherapies to reduce Abeta in brain and plasma, and drugs to modulate cholesterol-mediated effects on Abeta transport. Strategies are also underway to minimize toxic effects of Abeta fibrils on neurons, and these include antioxidants, blockers of glutamate-mediated excitotoxicity, and modulators of inflammatory responses within the brain. Although several approaches involve new agents for recently discovered targets, many are based on new applications of existing drugs such as statins and nonsteroidal anti-inflammatory drugs. Discovery of abnormally phosphorylated tau protein in neurofibrillary tangles in AD brain has led to strategies for identifying selective inhibitors of tau kinases and central nervous system/brain-permeable drugs that help maintain microtubule integrity. Clearly, a large gap exists between our understanding of the cellular cascades targeted in drug discovery and widespread failure of the nervous system that AD represents. Nevertheless, the pace of recent research clearly supports optimism that slowing progression of AD will soon be possible.
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Affiliation(s)
- Mary L Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, Kansas 66045-7582, USA.
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Sponne I, Fifre A, Drouet B, Klein C, Koziel V, Pinçon-Raymond M, Olivier JL, Chambaz J, Pillot T. Apoptotic neuronal cell death induced by the non-fibrillar amyloid-beta peptide proceeds through an early reactive oxygen species-dependent cytoskeleton perturbation. J Biol Chem 2003; 278:3437-45. [PMID: 12435748 DOI: 10.1074/jbc.m206745200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the present study, we have determined the nature and the kinetics of the cellular events triggered by the exposure of cells to non-fibrillar amyloid-beta peptide (A beta). When cortical neurons were treated with low concentrations of soluble A beta (1-40), an early reactive oxygen species (ROS)-dependent cytoskeleton disruption precedes caspase activation. Indeed, caspase activation and neuronal cell death were prevented by the microtubule-stabilizing drug taxol. A perturbation of the microtubule network was noticeable after being exposed to A beta for 1 h, as revealed by electron microscopy and immunocytochemistry. Microtubule disruption and neuronal cell death induced by A beta were inhibited in the presence of antioxidant molecules, such as probucol. These data highlight the critical role of ROS production in A beta-mediated cytoskeleton disruption and neuronal cell death. Finally, using FRAP (fluorescence recovery after photo bleaching) analysis, we observed a time-dependent biphasic modification of plasma membrane fluidity, as early as microtubule disorganization. Interestingly, molecules that inhibited neurotubule perturbation and cell death did not affect the membrane destabilizing properties of A beta, suggesting that the lipid phase of the plasma membrane might represent the earliest target for A beta. Altogether our results convey the idea that upon interaction with the plasma membrane, the non-fibrillar A beta induces a rapid ROS-dependent disorganization of the cytoskeleton, which results in apoptosis.
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Affiliation(s)
- Isabelle Sponne
- INSERM EMI 0014, Université de Nancy I, 54505 Vandoeuvre, France
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Li G, Faibushevich A, Turunen BJ, Yoon SO, Georg G, Michaelis ML, Dobrowsky RT. Stabilization of the cyclin-dependent kinase 5 activator, p35, by paclitaxel decreases beta-amyloid toxicity in cortical neurons. J Neurochem 2003; 84:347-62. [PMID: 12558997 DOI: 10.1046/j.1471-4159.2003.01526.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One hallmark of Alzheimer's disease (AD) is the formation of neurofibrillary tangles, aggregated paired helical filaments composed of hyperphosphorylated tau. Amyloid-beta (Abeta) induces tau hyperphosphorylation, decreases microtubule (MT) stability and induces neuronal death. MT stabilizing agents have been proposed as potential therapeutics that may minimize Abeta toxicity and here we report that paclitaxel (taxol) prevents cell death induced by Abeta peptides, inhibits Abeta-induced activation of cyclin-dependent kinase 5 (cdk5) and decreases tau hyperphosphorylation. Taxol did not inhibit cdk5 directly but significantly blocked Abeta-induced calpain activation and decreased formation of the cdk5 activator, p25, from p35. Taxol specifically inhibited the Abeta-induced activation of the cytosolic cdk5-p25 complex, but not the membrane-associated cdk5-p35 complex. MT-stabilization was necessary for neuroprotection and inhibition of cdk5 but was not sufficient to prevent cell death induced by overexpression of p25. As taxol is not permeable to the blood-brain barrier, we assessed the potential of taxanes to attenuate Abeta toxicity in adult animals using a succinylated taxol analog (TX67) permeable to the blood-brain barrier. TX67, but not taxol, attenuated the magnitude of both basal and Abeta-induced cdk5 activation in acutely dissociated cortical cultures prepared from drug treated adult mice. These results suggest that MT-stabilizing agents may provide a therapeutic approach to decrease Abeta toxicity and neurofibrillary pathology in AD and other tauopathies.
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Affiliation(s)
- Guibin Li
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence 66045, USA
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Michaelis ML, Dobrowsky RT, Li G. Tau neurofibrillary pathology and microtubule stability. J Mol Neurosci 2002; 19:289-93. [PMID: 12540054 DOI: 10.1385/jmn:19:3:289] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2002] [Accepted: 10/28/2002] [Indexed: 11/11/2022]
Abstract
We previously reported that nonomolar concentrations of Taxol and several structurally diverse microtubule (MT)-stabilizing agents significantly enhanced the survival of neurons in the presence of fibrils of amyloid beta peptide (Abeta). Pretreatment of neurons with MT-stabilizing drugs also blocked Abeta-induced activation of tau hyperphosphorylation. Although tau is a substrate for several kinases, we initially focused on cdk5, as this tau kinase has been shown to be activated in Abeta-treated neurons and Alzheimer's disease (AD) brain. In an in vitro kinase assay, Taxol inhibited activation of cdk5 by Abeta. In addition, the proposed cellular cascade in which calpain activation leads to cleavage of the cdk5 regulator, p35, to the strong kinase activator p25 was also prevented. Taxol did not directly inhibit the activity of either cdk5 or calpain, indicating that other cellular components are required for the effect of the drug on Abeta activation of tau phosphorylation. Our results suggest that drugs that interact with MTs can alter signaling events in neurons, possibly because some MTs play a role in organizing protein complexes involved in responses to Abeta. Thus the cytoskeletal network may serve as a biosensor of cellular well-being.
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Affiliation(s)
- Mary L Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, Malott Hall 5064, 1251 Wescoe Hall Drive, Lawrence, KS 66045-7582, USA.
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Kingston DGI, Jagtap PG, Yuan H, Samala L. The chemistry of taxol and related taxoids. FORTSCHRITTE DER CHEMIE ORGANISCHER NATURSTOFFE = PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS. PROGRES DANS LA CHIMIE DES SUBSTANCES ORGANIQUES NATURELLES 2002; 84:53-225. [PMID: 12132389 DOI: 10.1007/978-3-7091-6160-9_2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- D G I Kingston
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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Michaelis ML, Chen Y, Hill S, Reiff E, Georg G, Rice A, Audus K. Amyloid peptide toxicity and microtubule-stabilizing drugs. J Mol Neurosci 2002; 19:101-5. [PMID: 12212764 DOI: 10.1007/s12031-002-0018-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2001] [Accepted: 10/16/2001] [Indexed: 11/26/2022]
Abstract
Based on microtubule (MT) disruption observed in primary neurons exposed to fibrillar amyloid peptides (A beta), we tested the potential protective effect of MT-stabilizing drugs such as Taxol against A beta-induced disruption of the cytoskeleton. Although Taxol was strongly protective, the fact that it does not cross the blood brain barrier (BBB) led us to synthesize and test other agents with MT-stabilizing properties and possible penetration into the brain. Our studies have thus far demonstrated that several MT-stabilizing agents, including some with structures quite different from that of Taxol, showed significant protective effects. However, not all agents that promoted MT-assembly were protective, suggesting additional mechanisms are involved in the actions of the drugs. A small number of neuroprotective compounds appear to have potential to enter the brain and thus might be tested to see if they slow progression of neurodegeneration in an appropriate animal model of Alzheimer's disease.
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Affiliation(s)
- Mary L Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence 66045, USA.
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Edelstein-keshet L, Spiros A. Exploring the formation of Alzheimer's disease senile plaques in silico. J Theor Biol 2002; 216:301-26. [PMID: 12183120 DOI: 10.1006/jtbi.2002.2540] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An experimental simulation environment suitable for exploring the neuroinflammatory hypothesis of Alzheimer's disease (AD) has been developed. Using scientific literature, we have calculated parameters and rates and constructed an interactive model system. The simulation can be manipulated to explore competing hypotheses about AD pathology, i.e. can be used as an experimental "in silico" system. In this paper, we outline the assumptions and aspects of the model, and illustrate qualitative and quantitative findings. The interactions of amyloid beta deposits, glial cell dynamics, inflammation and secreted cytokines, and the stress, recovery, and death of neuronal tissue are investigated. The model leads to qualitative insights about relative roles of the cells and chemicals in the disease pathology.
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Affiliation(s)
- Leah Edelstein-keshet
- Department of Mathematics, University of British Columbia, Vancouver, BC, Canada,V6 T 1Z2.
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Abstract
Bcl-2, an antiapoptotic protein, protects cells against many but not all forms of apoptosis. For example, Bcl-2 does not protect non-neuronal cells against taxol, a microtubule-stabilizing agent. The underlying mechanism for the ineffectiveness of Bcl-2 against taxol has been the subject of intense interest. Data from non-neuronal cells indicate that taxol-induced apoptosis requires activation of N-terminal c-Jun protein kinase (JNK) that phosphorylates and inactivates Bcl-2. This suggests the interesting possibility that the apoptotic activity of JNK may be caused by phosphorylation of Bcl-2 and inhibition of the antiapoptotic activity of Bcl-2. Here we report that taxol induces apoptosis in cortical neurons but by a mechanism significantly different from that in non-neuronal cells. In contrast to human embryonic kidney 293 cells, expression of wild-type Bcl-2 in cortical neurons protected against taxol-induced apoptosis, and taxol did not induce Bcl-2 phosphorylation. Furthermore, cortical neurons express high basal JNK activity, and taxol did not stimulate total JNK activity. However, taxol activated a subpool of JNK in the nucleus and stimulated c-Jun phosphorylation. JNK inhibition or expression of a dominant-negative c-Jun abrogated taxol-induced apoptosis in cortical neurons, suggesting a role for JNK and JNK-mediated transcription in taxol-stimulated apoptosis. Furthermore, taxol-induced apoptosis in cortical neurons required inhibition of phosphatidylinositol 3-kinase signaling. These data suggest that taxol induces apoptosis in neurons by a mechanism quite distinct from that of non-neuronal cell lines and emphasize the importance of elucidating apoptotic mechanisms specific for neurons in the CNS.
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