Chemistry: molecular biology and microbiology – Animal cell – per se ; composition thereof; process of...
Reexamination Certificate
2001-07-31
2004-10-12
Kunz, Gary (Department: 1647)
Chemistry: molecular biology and microbiology
Animal cell, per se ; composition thereof; process of...
C435S347000, C435S352000, C435S353000, C435S354000
Reexamination Certificate
active
06803233
ABSTRACT:
FIELD OF THE INVENTION
The invention is in the field of models for medical diseases. Specifically, the invention is in the field of neurodegenerative disease models, and especially, Alzheimer's disease models.
BACKGROUND OF THE INVENTION
As human life span has significantly expanded over the last century, Alzheimer's disease and other neurodegenerative diseases will have a growing impact on the quality of life for a large proportion of the population. For example, Alzheimer's disease is a leading cause of dementia in the elderly, affecting 5-10% of the population over the age of 65 years. See
A Guide to Understanding Alzheimer's disease and Related Disorders
, edited by Jorm, New York University Press, New York (1987). Alzheimer's disease often presents with a subtle onset of memory loss followed by a slow progressive dementia over several years. The prevalence of Alzheimer's disease and other dementias doubles every five years beyond the age of 65. See 1997
Progress Report on Alzheimer's disease, National Institute on Aging/National Institute of Health
. Alzheimer's disease now affects 12 million people around the world, and it is projected to increase to 22 million by 2025 and to 45 million by 2050. See
Alzheimer's Association Press Release
, Jul. 18, 2000.
The complexity of the brain's architecture and chemistry, and the complexity of these neurodegenerative brain diseases, especially Alzheimer's disease, has hampered the development of a model that mimics many of the changes seen in the human brain. Such a model is needed in order to identify drugs or other agents that might be useful in treating, preventing or reversing the effects of such diseases.
Alzheimer's disease is histopathologically characterized by the loss of particular groups of neurons and the appearance of two principal lesions within the brain, termed senile plaques and neurofibrillary tangles. See Brion et al.,
J. Neurochem.
60:1372-1382 (1993). Senile plaques occur in the extracellular space. A major component of senile plaques is beta-amyloid (A-beta), a naturally secreted but insoluble peptide formed by cleavage of amyloid precursor protein (APP). A-beta is a fragment close to the carboxyterminal domain of APP.
Neurofibrillary tangles are intraneuronal accumulations of filamentous material in the form of loops, coils or tangled masses. They are most abundantly present in parts of the brain associated with memory functions, such as the hippocampus and adjacent parts of the temporal lobe. See Robbins Pathologic Basis of Disease, Cotran et al., 6
th
ed. (1999). Neurofibrillary tangles are commonly found in cortical neurons, especially in the entorhinal cortex, as well as in other locations such as pyramidal cells of the hippocampus, the amygdala, the basal forebrain, and the raphe nuclei.
Neurofibrillary tangles can also be found during normal aging of the brain, however, they are found in a significantly higher density in the brain of Alzheimer's disease patients, and in the brains of patients with other neurodegenerative diseases, such as progressive supranuclear palsy, postencephaltic Parkinson disease, Pick's disease, amylotrophic lateral sclerosis, etc.
Robbins Pathologic Basis of Disease
, Cotran et al., 6th ed. (1999), p.1330. Previous studies suggest that, among other things, neurofibrillary tangles may significantly contribute to the cognitive decline associated with the disease and also directly to neuronal cell death.
Ultrastructurally, neurofibrillary tangles are composed predominantly of paired helical filaments (“PHF”). A major component of PHF is an abnormally phosphorylated form of a protein called tau and its fragments.
Robbins Pathologic Basis of Disease
, Cotran et al., 6th ed., W. B. Saunders Company (1999), p.1300.
The tau protein (also referred to as “native tau”) is a microtubule-associated phosphoprotein that stabilizes the cytoskeleton and contributes to determining neuronal shape. See Kosik & Caceres,
Cell Sci. Suppl.
14:69-74 (1991). Tau has an apparent molecular weight of about 55 kDa. The protease cathepsin D cleaves tau protein at neutral (cytoplasmic) pH resulting in tau fragments—one of which has a molecular weight of approximately 29 kDa (referred to by some authors as “tau fragment”). See, e.g., Bednarski & Lynch,
J. Neurochem.
67:1846-1855 (1996); Bednarski & Lynch,
NeuroReport
9:2089-2094 (1998). Both the tau protein and 29 kDa tau fragment can be phosphorylated. In a normal brain, the tau protein and tau fragment typically exist in an unphosphorylated, or dephosphorylated state. However, in neurofibrillary tangles, both tau protein and tau fragment can be found in an abnormally phosphorylated state, a hyperphosphorylated state. The 29 kDa tau fragment is a major component of neurofibrillary tangles. Hyperphosphorylation impairs tau protein's ability to interact with microtubules.
Bednarski E, and Lynch G,
J Neurochem
67:1846-55 (1996) cultured hippocampal slices with an inhibitor [N-CBZ-L-phenylalanyl-L-alanine-diazomethyl ketone (ZPAD)] of cathepsins B and L. The authors reported that this resulted in the degradation of high molecular weight isoforms of tau protein and the production of a 29-kDa tau fragment (tau 29).
Bednarski E, and Lynch G,
Neuroreport
9:2089-2094 (1998) reported that incubating cultured hippocampal slices with chloroquine or with ZPAD resulted in increases in enzymatically active cathepsin D and the delayed appearance of a 29 kDa fragment of the tau protein. The authors proposed that inactivation of cathepsin L leads to induction of cathepsin D which leads to aberrant tau proteolysis and that such a pathway is likely to play an important role in brain aging.
In addition to the build-up of A-beta and of neurofibrillary tangles, increasing evidence has pointed to a link between lipid metabolism and Alzheimer's disease. Epidemiological studies found that patients with increased plasma cholesterol levels and cardiovascular diseases have an increased risk of Alzheimer's disease (Jick, H., et al.,
Lancet
356:627-631 (2000)). Also, long-term therapy with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors appears to decrease the prevalence of Alzheimer's disease (Jick, H., et al.,
Lancet
356:627-631 (2000); Wolozin, B., et al.,
Arch. Neurol.
57:1439-1443 (2000)).
Consistent with a link to lipid metabolism, in vitro experiments have shown that cholesterol affects the generation and aggregation of beta amyloid (A-beta) (Bodovitz, S., and Klein, W. L.,
J. Biol. Chem.
271:4436-4440 (1996); Xu, H., et al.,
Proc. Natl. Acad. Sci. U S A
94:3748-3752 (1997); Howland, D. S., et al.,
J. Biol. Chem.
273:16576-16582 (1998) ). Transgenic mice fed a high cholesterol diet also developed increased amounts of A-beta deposition (Refolo, L. M., et al.,
Neurobiol. Dis.
7:321-331 (2000)).
ApoE-mediated transport of cholesterol into lysosomes is a critical step for cells to utilize these sterols, which is of particular importance for mature neurons that mainly rely on extracellular cholesterol (Brown, M. S., and Goldstein, J. L.,
Annu. Rev. Biochem.
52:223-261 (1983)). Once in the lysosome, cholesterol and other lipids dissociate from ApoE before being utilized by the cell (Brown, M. S., and Goldstein, J. L.,
Annu. Rev. Biochem.
52:223-261 (1983)).
Changes in cholesterol levels may be involved in certain neurodegenerative diseases. For example, accumulation of insoluble A-beta1-42 has been found in Niemann-Pick type C (NPC) mutant cells (Yamazaki, T., et al.,
J. Biol. Chem
. (2000)(epub ahead of print)). These cells exhibit many pathologic characteristics, one of which is impaired intracellular transport of cholesterol (Millard, E. E., et al.,
J. Biol. Chem.
275:38445-38451 (2000)). Also, the ApoE4 isoform is a known risk factor for late-onset Alzheimer's disease.
Inhibition of cholesterol synthesis enhanced the phosphorylation of tau in dissociated cell cultures [ref. in (Sawamura, N., et al.,
J. Biol. Chem.
57:1439
Bi Xiaoning
Lynch Gary
Nichols Christopher James
Sterne Kessler Goldstein & Fox P.L.L.C.
The Regents of the University of California
LandOfFree
Model for Alzheimer's disease and other... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Model for Alzheimer's disease and other..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Model for Alzheimer's disease and other... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3264356