Cysteine proteases are the major ?-secretase in the regulated secretory pathway that provides most of the ?-amyloid in Alzheimer's disease: Role of BACE 1 in the constitutive secretory pathway

2003 ◽  
Vol 74 (3) ◽  
pp. 393-405 ◽  
Author(s):  
Vivian Y.H. Hook ◽  
Terry D. Reisine
2005 ◽  
Vol 386 (9) ◽  
Author(s):  
Vivian Hook ◽  
Thomas Toneff ◽  
Matthew Bogyo ◽  
Doron Greenbaum ◽  
Katalin F. Medzihradszky ◽  
...  

AbstractThe regulated secretory pathway of neurons is the major source of extracellular Aβ that accumulates in Alzheimer's disease (AD). Extracellular Aβ secreted from that pathway is generated by β-secretase processing of amyloid precursor protein (APP). Previously, cysteine protease activity was demonstrated as the major β-secretase activity in regulated secretory vesicles of neuronal chromaffin cells. In this study, the representative cysteine protease activity in these secretory vesicles was purified and identified as cathepsin B by peptide sequencing. Immunoelectron microscopy demonstrated colocalization of cathepsin B with Aβ in these vesicles. The selective cathepsin B inhibitor, CA074, blocked the conversion of endogenous APP to Aβ in isolated regulated secretory vesicles. In chromaffin cells, CA074Me (a cell permeable form of CA074) reduced by about 50% the extracellular Aβ released by the regulated secretory pathway, but CA074Me had no effect on Aβ released by the constitutive pathway. Furthermore, CA074Me inhibited processing of APP into the COOH-terminal β-secretase-like cleavage product. These results provide evidence for cathepsin B as a candidate β-secretase in regulated secretory vesicles of neuronal chromaffin cells. These findings implicate cathepsin B as β-secretase in the regulated secretory pathway of brain neurons, suggesting that inhibitors of cathepsin B may be considered as therapeutic agents to reduce Aβ in AD.


2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Gang Luo ◽  
Hongxia Xu ◽  
Yinuo Huang ◽  
Dapeng Mo ◽  
Ligang Song ◽  
...  

The main causes of Alzheimer’s disease remain elusive. Previous data have implicated the BACE-1 protein as a central player in the pathogenesis of Alzheimer’s disease. However, many inhibitors of BACE-1 have failed during preclinical and clinical trials for AD treatment. Therefore, uncovering the exact role of BACE-1 in AD may have significant impact on the future development of therapeutic agents. Three- and six-month-old female APP/PS1 double transgenic mice were used to study abnormal accumulation of BACE-1 protein in brains of mice here. Immunofluorescence, immunohistochemistry, and western blot were performed to measure the distributing pattern and expression level of BACE-1. We found obvious BACE-1 protein accumulation in 3-month-old APP/PS1 mice, which had increased by the time of 6 months. Coimmunostaining results showed BACE-1 surrounded amyloid plaques in brain sections. The abnormal protein expression might not be attributable to the upregulation of BACE-1 protein, as no significant difference of protein expression was observed between wild-type and APP/PS1 mice. With antibodies against BACE-1 and CD31, we found a high immunoreactive density of BACE-1 protein on the outer layer of brain blood vessels. The aberrant distribution of BACE-1 in APP/PS1 mice suggests BACE-1 may be involved in the microvascular abnormality of AD.


2011 ◽  
Vol 44 (06) ◽  
Author(s):  
K Lerche ◽  
M Willem ◽  
K Kleinknecht ◽  
C Romberg ◽  
U Konietzko ◽  
...  

2020 ◽  
Vol 3 (2) ◽  
pp. 216-242 ◽  
Author(s):  
Mayuri Shukla ◽  
Areechun Sotthibundhu ◽  
Piyarat Govitrapong

The revelation of adult brain exhibiting neurogenesis has established that the brain possesses great plasticity and that neurons could be spawned in the neurogenic zones where hippocampal adult neurogenesis attributes to learning and memory processes. With strong implications in brain functional homeostasis, aging and cognition, various aspects of adult neurogenesis reveal exuberant mechanistic associations thereby further aiding in facilitating the therapeutic approaches regarding the development of neurodegenerative processes in Alzheimer’s Disease (AD). Impaired neurogenesis has been significantly evident in AD with compromised hippocampal function and cognitive deficits. Melatonin the pineal indolamine augments neurogenesis and has been linked to AD development as its levels are compromised with disease progression. Here, in this review, we discuss and appraise the mechanisms via which melatonin regulates neurogenesis in pathophysiological conditions which would unravel the molecular basis in such conditions and its role in endogenous brain repair. Also, its components as key regulators of neural stem and progenitor cell proliferation and differentiation in the embryonic and adult brain would aid in accentuating the therapeutic implications of this indoleamine in line of prevention and treatment of AD.   


2020 ◽  
Vol 37 (2) ◽  
pp. 1-12
Author(s):  
Sara M. Kamal ◽  
Aliaa R.H. Mostafa ◽  
Sanaa M.R. Wahba

2020 ◽  
Vol 21 (12) ◽  
pp. 1164-1173
Author(s):  
Siju Ellickal Narayanan ◽  
Nikhila Sekhar ◽  
Rajalakshmi Ganesan Rajamma ◽  
Akash Marathakam ◽  
Abdullah Al Mamun ◽  
...  

: Alzheimer’s disease (AD) is a progressive brain disorder and one of the most common causes of dementia and death. AD can be of two types; early-onset and late-onset, where late-onset AD occurs sporadically while early-onset AD results from a mutation in any of the three genes that include amyloid precursor protein (APP), presenilin 1 (PSEN 1) and presenilin 2 (PSEN 2). Biologically, AD is defined by the presence of the distinct neuropathological profile that consists of the extracellular β-amyloid (Aβ) deposition in the form of diffuse neuritic plaques, intraneuronal neurofibrillary tangles (NFTs) and neuropil threads; in dystrophic neuritis, consisting of aggregated hyperphosphorylated tau protein. Elevated levels of (Aβ), total tau (t-tau) and phosphorylated tau (ptau) in cerebrospinal fluid (CSF) have become an important biomarker for the identification of this neurodegenerative disease. The aggregation of Aβ peptide derived from amyloid precursor protein initiates a series of events that involve inflammation, tau hyperphosphorylation and its deposition, in addition to synaptic dysfunction and neurodegeneration, ultimately resulting in dementia. The current review focuses on the role of proteomes in the pathogenesis of AD.


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