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ABSTRACT: BACE1 is required for the release of beta-amyloid (Abeta) in vivo, and inhibition of BACE1 activity is targeted for reducing Abeta generation in Alzheimer's patients. To further our understanding of the safe use of BACE1 inhibitors in human patients, we aimed to study the physiological functions of BACE1 by characterizing BACE1-null mice. Here, we report the finding of spontaneous behavioral seizures in BACE1-null mice. Electroencephalographic recordings revealed abnormal spike-wave discharges in BACE1-null mice, and kainic acid-induced seizures also occurred more frequently in BACE1-null mice compared with their wild-type littermates. Biochemical and morphological studies showed that axonal and surface levels of Na(v)1.2 were significantly elevated in BACE1-null mice, consistent with the increased fast sodium channel current recorded from BACE1-null hippocampal neurons. Patch-clamp recording also showed altered intrinsic firing properties of isolated BACE1-null hippocampal neurons. Furthermore, population spikes were significantly increased in BACE1-null brain slices, indicating hyperexcitability of BACE1-null neurons. Together, our results suggest that increased sodium channel activity contributes to the epileptic behaviors observed in BACE1-null mice. The knowledge from this study is crucial for the development of BACE1 inhibitors for Alzheimer's therapy and to the applicative study of epilepsy.
Journal of Neuroscience 06/2010; 30(26):8819-29. · 7.11 Impact Factor
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ABSTRACT: Bace1 is an endopeptidase that cleaves the amyloid precursor protein at the beta-secretase site. Apart from this cleavage, the functional importance of Bace1 in other physiological events is unknown. We show here that Bace1 regulates the process of myelination and myelin sheath thickness in the central and peripheral nerves. In Bace1-null mice, the process of myelination was delayed and myelin thickness was markedly reduced, indicating that genetic deletion of Bace1 causes hypomyelination. Bace1-null mice also showed altered neurological behaviors such as elevated pain sensitivity and reduced grip strength. Further mechanistic studies showed an altered neuregulin-Akt signaling pathway in Bace1-null mice. Full-length neuregulin-1 was increased and its cleavage product was decreased in the CNS of Bace1-null mice. Furthermore, phosphorylated Akt was also reduced. Based upon these and previous studies, we postulate that neuronally enriched Bace1 cleaves neuregulin-1 and that processed neuregulin-1 regulates myelination by means of phosphorylation of Akt in myelin-forming cells.
Nature Neuroscience 01/2007; 9(12):1520-5. · 15.53 Impact Factor
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Rena Li,
Kristina Lindholm,
Li-Bang Yang,
Xu Yue,
Martin Citron,
Riqiang Yan,
Thomas Beach,
Lucia Sue,
Marwan Sabbagh,
Huaibin Cai, Philip Wong,
Donald Price,
Yong Shen
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ABSTRACT: Whether elevated beta-secretase (BACE) activity is related to plaque formation or amyloid beta peptide (Abeta) production in Alzheimer's disease (AD) brains remains inconclusive. Here, we report that we used sandwich enzyme-linked immunoabsorbent assay to quantitate various Abeta species in the frontal cortex of AD brains homogenized in 70% formic acid. We found that most of the Abeta species detected in rapidly autopsied brains (<3 h) with sporadic AD were Abeta(1-x) and Abeta(1-42), as well as Abeta(x-42). To establish a linkage between Abeta levels and BACE, we examined BACE protein, mRNA expression and enzymatic activity in the same brain region of AD brains. We found that both BACE mRNA and protein expression is elevated in vivo in the frontal cortex. The elevation of BACE enzymatic activity in AD is correlated with brain Abeta(1-x) and Abeta(1-42) production. To examine whether BACE elevation was due to mutations in the BACE-coding region, we sequenced the entire ORF region of the BACE gene in these same AD and nondemented patients and performed allelic association analysis. We found no mutations in the ORF of the BACE gene. Moreover, we found few changes of BACE protein and mRNA levels in Swedish mutated amyloid precursor protein-transfected cells. These findings demonstrate correlation between Abeta loads and BACE elevation and also suggest that as a consequence, BACE elevation may lead to increased Abeta production and enhanced deposition of amyloid plaques in sporadic AD patients.
Proceedings of the National Academy of Sciences 04/2004; 101(10):3632-7. · 9.68 Impact Factor
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Li-Bang Yang,
Kristina Lindholm,
Riqiang Yan,
Martin Citron,
Weiming Xia,
Xiao-Li Yang,
Thomas Beach,
Lucia Sue, Philip Wong,
Donald Price,
Rena Li,
Yong Shen
Nature Medicine 02/2003; 9(1):3-4. · 22.46 Impact Factor
