Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues
Reexamination Certificate
1999-12-22
2002-06-25
McGarry, Sean (Department: 1635)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
C530S300000
Reexamination Certificate
active
06410689
ABSTRACT:
BACKGROUND OF THE INVENTION
In multicellular organisms, homeostasis is maintained by balancing the rate of cell proliferation against the rate of cell death. Cell proliferation is influenced by numerous growth factors and the expression of proto-oncogenes, which typically encourage progression through the cell cycle. In contrast, numerous events, including the expression of tumor suppressor genes, can lead to an arrest of cellular proliferation.
In differentiated cells, a particular type of cell death called apoptosis occurs when an internal suicide program is activated. This program can be initiated by a variety of external signals as well as signals that are generated within the cell in response to, for example, genetic damage. For many years, the magnitude of apoptotic cell death was not appreciated because the dying cells are quickly eliminated by phagocytes, without an inflammatory response.
The mechanisms that mediate apoptosis have been intensively studied. These mechanisms involve the activation of endogenous proteases, loss of mitochondrial function, and structural changes such as disruption of the cytoskeleton, cell shrinkage, membrane blebbing, and nuclear condensation due to degradation of DNA. The various signals that trigger apoptosis are thought to bring about these events by converging on a common cell death pathway that is regulated by the expression of genes that are highly conserved from worms, such as
C. elegans
, to humans. In fact, invertebrate model systems have been invaluable tools in identifying and characterizing the genes that control apoptosis. Through the study of invertebrates and more evolved animals, numerous genes that are associated with cell death have been identified, but the way in which their products interact to execute the apoptotic program is poorly understood.
Caspases, a class of proteins central to the apoptotic program, are cysteine protease having specificity for aspartate at the substrate cleavage site. These proteases are primarily responsible for the degradation of cellular proteins that lead to the morphological changes seen in cells undergoing apoptosis. For example, one of the caspases identified in humans was previously known as the interleukin-1&bgr; (IL-1&bgr;) converting enzyme (ICE), a cysteine protease responsible for the processing of pro-IL-1&bgr; to the active cytokine. Overexpression of ICE in Rat-1 fibroblasts induces apoptosis (Miura et al., Cell 75:653 [1993]).
Many caspases and proteins that interact with caspases possess domains of about 60 amino acids called a caspase recruitment domain (CARD). Hofmann et al. (TIBS 22:155 [1997]) and others have postulated that certain apoptotic proteins bind to each other via their CARDs and that different subtypes of CARDs may confer binding specificity, regulating the activity of various caspases, for example.
The functional significance of CARDs have been demonstrated in two recent publications. Duan et al. (Nature 385:86 [1997]) showed that deleting the CARD at the N-terminus of RAIDD, a newly identified protein involved in apoptosis, abolished the ability of RAIDD to bind to caspases. In addition, Li et al. (Cell 91:479 [1997]) showed that the N-terminal 97 amino acids of apoptotic protease activating factor-1 (Apaf-1) was sufficient to confer caspase-9-binding ability.
SUMMARY OF THE INVENTION
The invention relates to the discovery of two genes, card-3 (cDNA in
FIG. 2
, SEQ ID NO:2) and card-4 (partial cDNA in
FIG. 4
, SEQ ID NO:4), which encode the CARD-containing proteins CARD-3 (
FIG. 1
, SEQ ID NO:1) and CARD-4 (partial sequence in
FIG. 3
, SEQ ID NO:3).
CARD-3 contains a kinase domain at amino acid positions 1-300, followed by a linker domain at positions 301-431 and a CARD at positions 432-540. In the CARD-4 partial amino acid sequence (
FIG. 3
, SEQ ID NO:3), a CARD is located at positions 3-72, counting the first Ser in the sequence as the first position.
Like other proteins containing a CARD, CARD-3 and CARD-4 are expected to participate in the network of interactions that lead to caspase activation. Accordingly, the human card-3 and card-4 genes described herein may be useful in diagnostic and therapeutic applications directed to the regulation of cell growth and death such as the diagnosis of certain cancers, e.g., breast cancer and colorectal cancer. These genes and the proteins they encode can be used to screen for molecules which inhibit or enhance CARD-3 or CARD-4 activity. Moreover, agonist ligands which bind to the proteins encoded by these genes may be useful for the treatment of certain cancers.
The invention encompasses methods of diagnosing and treating patients who are suffering from a disorder associated with an abnormal level or rate (undesirably high or undesirably low) of apoptotic cell death, abnormal activity of the Fas/APO-1 receptor complex, abnormal activity of the TNF receptor complex, or abnormal activity of a caspase by administering a compound that modulates the expression of CARD-3 and/or CARD-4 (at the DNA, mRNA or protein level, e.g., by altering mRNA splicing) or by altering the activity of CARD-3 and/or CARD-4. Examples of such compounds include small molecules, antisense nucleic acid molecules, ribozymes, and polypeptides.
Certain disorders are associated with an increased number of surviving cells, which are produced and continue to survive or proliferate when apoptosis is inhibited. These disorders include cancer (particularly follicular lymphomas, carcinomas associated with mutations in p53, and hormone-dependent tumors such as breast cancer, prostate cancer, and ovarian cancer), autoimmune disorders (such as systemic lupus erythematosis, immune-mediated glomerulonephritis), and viral infections (such as those caused by herpesviruses, poxviruses, and adenoviruses).
Failure to remove autoimmune cells that arise during development or that develop as a result of somatic mutation during an immune response can result in autoimmune disease. One of the molecules that plays a critical role in regulating cell death in lymphocytes is the cell surface receptor for Fas.
Populations of cells are often depleted in the event of viral infection, with perhaps the most dramatic example being the cell depletion caused by the human immunodeficiency virus (HIV). Surprisingly, most T cells that die during HIV infections do not appear to be infected with HIV. Although a number of explanations have been proposed, recent evidence suggests that stimulation of the CD4 receptor results in the enhanced susceptibility of uninfected T cells to undergo apoptosis.
A wide variety of neurological diseases are characterized by the gradual loss of specific sets of neurons. Such disorders include Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) retinitis pigmentosa, spinal muscular atrophy, and various forms of cerebellar degeneration. The cell loss in these diseases does not induce an inflammatory response, and apoptosis appears to be the mechanism of cell death.
In addition, a number of hematologic diseases are associated with a decreased production of blood cells. These disorders include anemia associated with chronic disease, aplastic anemia, chronic neutropenia, and the myelodysplastic syndromes. Disorders of blood cell production, such as myelodysplastic syndrome and some forms of aplastic anemia, are associated with increased apoptotic cell death within the bone marrow. These disorders could result from the activation of genes that promote apoptosis, acquired deficiencies in stromal cells or hematopoietic survival factors, or the direct effects of toxins and mediators of immune responses.
Two common disorders associated with cell death are myocardial infarctions and stroke. In both disorders, cells within the central area of ischemia, which is produced in the event of acute loss of blood flow, appear to die rapidly as a result of necrosis. However, outside the central ischemic zone, cells die over a more protracted time period and morphologically appear to die by apoptosis.
Fish & Richardson P.C.
McGarry Sean
Millennium Pharmaceuticals Inc.
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