Human orthologues of wart

Details Human orthologues of wart Human orthologues of wart

1999-01-20

2002-12-17

Slobodyansky, Elizabeth (Department: 1652)

Chemistry: molecular biology and microbiology

Enzyme , proenzyme; compositions thereof; process for...

C435S183000, C435S194000

Reexamination Certificate

active

06495353

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates in part to protein kinases. In particular, the invention concerns the identification of protein kinase proteins which are human orthologues of the drosophila WART gene (hWART).
BACKGROUND OF THE INVENTION
The following description is provided to aid in understanding the invention, but is not admitted to describe or constitute prior art to the invention.
Cellular signal transduction is a fundamental mechanism whereby extracellular stimuli are relayed to the interior of cells and thereby regulate diverse cellular processes. One of the key biochemical mechanisms of signal transduction involves the reversible phosphorylation of proteins. Phosphorylation of polypeptides regulates the activity of mature proteins by altering their structure and function. Phosphate most often resides on the hydroxyl moiety of serine, threonine, or tyrosine amino acids in proteins.
Enzymes that mediate phosphorylation of cellular effectors generally fall into two classes. The first class consists of protein kinases which transfer a phosphate moiety from nucleotide triposphates to protein substrates. The second class consists of protein phosphatases which hydrolyze phosphate moieties from phosphoryl protein substrates. The converse functions of protein kinases and protein phosphatases balance and regulate the flow of signals in signal transduction processes.
Protein kinases are generally divided into two classes: receptor and non-receptor type proteins. Protein kinases may also be divided into three classes based upon the amino acids they act upon: (1) Some catalyze the addition or hydrolysis of phosphate on serine or threonine only; (2) some catalyze the addition or hydrolysis of phosphate on tyrosine only; and (3) some catalyze the addition or hydrolysis of phosphate on serine, threonine, and tyrosine.
Altered protein kinase activity has been associated with multiple abnormal cellular functions, including increased cell proliferation. Increased cell proliferation can result from at least two cellular events: (i) mutation, chromosome translocation, or gene amplification of proto-oncogenes (Bishop, Cell 64:235-248, 1991), or (ii) inactivation, loss by mutation, chromosomal loss, mitotic recombination, or gene conversion of tumor suppressor genes (Lasko et al., Ann Rev Genet 25:281-314).
A large number of potential tumor suppressor genes have been isolated from Drosophila melanogaster, a species of fruit fly. Watson et al., J. Cell Sci. 18:19-33 , 1994. Potential tumor suppressor genes are identified in this organism by first deleting, obstructing, or mutating a gene, and then detecting over-proliferative cell growth of specific tissues in dissected larvae and pupae. Xu et al., Development 121:1053-1063, 1995. This organism provides an ideal system for identifying potential tumor suppressor genes as it reproduces rapidly and its genome is readily manipulated by persons skilled in the art.
An example of a putative tumor suppressor gene, identified in Drosophila is the wts gene. Loss or inactivation of both copies of the wts gene results in the growth of tumors on the legs and wings of the flies. Bryant et al., Development 1993 Supplement: 239-249, 1993. The large size of these tumors suggests that the cells undergo more divisions than normal. Id. In addition, the rounded shape of the tumors suggests that the division of the mutant cells is not preferentially oriented. Id. These observations taken together with the increased thickness of the cuticles around the mutant cells suggest that the wts gene regulates cell adhesion, cell contact inhibition, and/or cell boundary recognition in Drosophila.
Several of the genes characterized as potential tumor suppressors in Drosophila are cloned. In particular, the wts gene contains a region that bears sequence similarity to the catalytic regions of mammalian non-receptor serine/threonine protein kinases. Watson, BioEssays 17:673-676, 1995. However, the human orthologues of the drosophila wts gene have not been reported.
SUMMARY OF THE INVENTION
The invention relates in part to novel human orthologues of the Drosophila wts gene (hWARTs). The Drosophila wts gene encodes a non-receptor serine/threonine kinase. The properties of the human orthologues are described herein. The present invention concerns polypeptides of hWART, nucleic acids encoding such polypeptides, cells, tissues and animals containing such nucleic acids, antibodies to the polypeptides, assays utilizing the polypeptides, and methods relating to all of the foregoing.
The term “orthologue” as used herein, refers to a gene that is more c related, in terms of nucleic acid sequence, to another gene than a gene which is a homologue. In the context of this invention, “homologous” indicates that the nucleotide sequences of two genes and/or the sequences of the gene products (e.g., amino acid sequences) have significant similarity, and that the gene products perform a similar cellular function. Thus, two homologous genes may have sequences which have 50, 60, 70, 80, 90, or greater percent nucleotide sequence identity. By “closely related” in the context of this invention, it is meant nucleic acid sequences that have greater than 90% identity.
The hWARTS genes encode proteins that are potential drug targets for controlling aberrant cell proliferation. Unlike their Drosophila ortholog, the hWARTS genes may not function as tumor suppressor genes. While their mRNA is absent from most normal cells they are abundantly expressed in many types of tumor cells. However, based on the high degree of sequence identity in the catalytic and non-catalytic regions between the hWART proteins and the Drosophila wts, it is likely that the hWART genes are involved in regulating cell adhesion, cell contact inhibition, and/or cell boundary recognition, and in regulation of signal transduction pathways related to cell proliferation.
Thus, in a first aspect, the invention features an isolated, enriched, or purified nucleic acid molecule encoding an hWART polypeptide.
By “isolated” in reference to nucleic acid it is meant a polymer of 14, 17, 21 or more nucleotides conjugated to each other, including DNA or RNA that is isolated from a natural source or that is synthesized. The isolated nucleic acid of the present invention is unique in the sense that it is not found in a pure or separated state in nature. Use of the term “isolated” indicates that a naturally occurring sequence has been removed from its normal cellular (i.e., chromosomal) environment. Thus, the sequence may be in a cell-free solution or placed in a different cellular environment. The term does not imply that the sequence is the only nucleotide sequence present, but that it is essentially free (about 90-95% pure at least) of non-nucleotide material naturally associated with it and thus is meant to be distinguished from isolated chromosomes.
By the use of the term “enriched” in reference to nucleic acid it is meant that the specific DNA or RNA sequence constitutes a significantly higher fraction (2-5 fold) of the total DNA or RNA present in the cells or solution of interest than in normal or diseased cells or in the cells from which the sequence was taken. This could be caused by a person by preferential reduction in the amount of other DNA or RNA present, or by a preferential increase in the amount of the specific DNA or RNA sequence, or by a combination of the two. However, it should be noted that “enriched” does not imply that there are no other DNA or RNA sequences present, just that the relative amount of the sequence of interest has been significantly increased.
The term “significant” here is used to indicate that the level of increase is useful to the person making such an increase, and generally means an increase relative to other nucleic acids of about at least 2 fold, more preferably at least 5 to 10 fold or even more. The term also does not imply that there is no DNA or RNA from other sources. The other source DNA may, for example, comprise DNA from a yeast or bacterial genome, or a cloning vector such as pUC

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