Chemistry: molecular biology and microbiology – Process of mutation – cell fusion – or genetic modification – Introduction of a polynucleotide molecule into or...
Reexamination Certificate
1999-06-04
2002-09-17
McKelvey, Terry (Department: 1636)
Chemistry: molecular biology and microbiology
Process of mutation, cell fusion, or genetic modification
Introduction of a polynucleotide molecule into or...
C435S320100, C435S410000, C536S023600, C800S278000, C800S295000
Reexamination Certificate
active
06451604
ABSTRACT:
FIELD OF INVENTION
This invention involves the modification of plant developmental responses. Specifically, this invention relates to polynucleotides and polypeptides that affect programmed cell death. These polynucleotides and polypeptides, and genetic constructs comprising such polynucleotides and polypeptides may be used to modulate programmed cell death and thereby alter the developmental cycle of forestry plant cells, hence altering plant development.
BACKGROUND OF THE INVENTION
Programmed cell death (PCD) refers to an active process, in which gene expression is intimately associated with the events leading to cell death. The plant life cycle contains many instances of such cell death. During plant reproduction and early embryogenesis, events such as organ ablation during unisexual flower development, tapetum degeneration during pollen development and suspensor degeneration during embryo development all involve an active cell death process. During plant morphogenesis and maturation, aleurone cell degradation, the terminal phase of tracheary element differentiation in xylem, leaf blade development in some plants (e.g. genus Monstera), leaf/organ senescence, root cap cell differentiation and the hypersensitive response in plant/pathogen interactions provide further examples of the role of cell death programs in plant developmental cycles.
Most of the scientific investigation relating to programmed cell death to date has involved PCD in mammalian cells. PCD in these cells is evidenced by distinct morphological characteristics, such as cytoplasmic condensation, membrane blebbing, DNA fragmentation, condensation and fragmentation of the nucleus, and finally cell corpse engulfment. In mammalian cells, PCD provides a mechanism for removing unwanted cells, as well as for removing pathogens or pathogen-infected cells. It is also believed that a breakdown in normal PCD mechanisms plays an important role in many disease states, including many malignancies.
The role of PCD in plant systems has not been studied extensively. Preliminary comparisons between plant and mammalian PCD mechanisms suggest some similarities in the mechanisms. The potential similarities include: an oxygen requirement; activation by hydrogen peroxide; a role for calcium in the activation process; a transcription requirement; a dephosphorylation requirement; proteolytic and nucleolytic enzyme involvement and cell condensation and shrinkage. Modulation of the PCD mechanism in any one or more of these areas may affect plant development.
SUMMARY OF THE INVENTION
Briefly, the present invention provides isolated polypeptides, and the polynucleotides encoding the isolated polypeptides, having activity in PCD pathways and various developmental pathways in forestry plant species. Genetic constructs comprising such polynucleotides and methods for the use of such genetic constructs to modulate PCD and various developmental pathways in forestry plants are also provided. Transgenic cells and plants incorporating such genetic constructs and exhibiting a modified content of the polynucleotides and/or polypeptides of the present invention compared to a wild-type plant, are also provided. Methods for modulating plant cell death,. as well as for modulating various forestry plant species developmental pathways, using the polynucleotides and/or polypeptides of the present invention, are disclosed.
In mammalian PCD, regulation of cell cycle entry appears to be important, and it has been suggested that cell cycle checkpoint regulators may be involved in the commitment of a cell to death. For example, the known tumor suppressor p45 is capable of mediating cell cycle arrest and can trigger PCD. One of the key genes involved in p45 mediated responses is the retinoblastoma gene (RB). This tumor suppressor can bind and inhibit the transcription factors that initiate entry into the cell cycle. In addition, RB plays a regulatory role in the cell death process, depending on its phosphorylation status. The regulation of RB proteolysis by phosphorylation status, and the consequent RB levels in the cells are important in the determination of cellular fates. Two polynucleotides encoding retinoblastoma-related polypeptides (SEQ ID NOS: 36, 37) have been isolated from forestry species. Retinoblastoma-related polypeptides encoded by the polynucleotides are identified as SEQ ID NOS: 80, 81.
Another tumor suppressor gene, prohibitin, can also arrest the cell cycle. In rat B lymphocytes, the association of prohibitin with membrane-bound IgM has been suggested as a mediator of PCD in these cells. Furthermore, in yeast, the deletion of prohibitin homologs resulted in a decreased replicative lifespan, leading to successive decreases in cell cycle time, ageing and cellular senescence. While the above studies have been conducted in non-plant systems, it is likely that similar cell cycle modulators are effective in plant systems. Several polynucleotides encoding prohibitin-related polypeptides (SEQ ID NOS: 22-26) have been isolated from forestry species. Prohibitin-related polypeptides encoded by the polynucleotides are identified as SEQ ID NOS: 67-71.
Polynucleotides associated with cellular housekeeping functions are necessary for cell health and survival, and their loss may lead to cell death. One such polynucleotide, initially identified in temperature-sensitive mutant hamster cell lines, was DAD1 (Defender Against Cell Death 1). Cells in temperature-sensitive mutant hamster cell lines undergo PCD at restrictive temperatures, and it has been shown that the Arabidopsis DAD1 can rescue the hamster temperature-sensitive mutant. The presence of DAD1 can also reduce cell death in the developing embryo of the worm
Caenorhabditis elegans
, which undergoes developmentally-regulated cell death. DAD1 has been shown to be a component of oligosaccharyltransferase, involved in N-linked glycosylation. The induction of cell death by DAD1 inactivation, as well as the ability of DAD1 to reduce PCD during development illustrates the essential role of this housekeeping gene. Several polynucleotides encoding DAD1-related polypeptides (SEQ ID NOS: 6-9) have been isolated from forestry species. DAD1-related polypeptides encoded by the polynucleotides are identified as SEQ ID NOS: 51-54.
Another housekeeping polynucleotide which may be used to control cell survival and cell death is the TATA Box Binding Protein (TFIID). TFIID is the most important general factor required for gene transcription by RNA Polymerase II. TFIID binds to the TATA box and participates in the first steps of transcription factor assembly, which is important for the control of gene expression. The ability to developmentally or tissue-specifically knock-out TFIID activity provides a method of specifically inducing cell death. Attempts at TFIID knock-out have not been reported for plants. Polynucleotides encoding TFIID-related transcription initiation factors (SEQ ID NOS: 41, 42) have been isolated from forestry species. TFIID-related transcription initiation factors encoded by the polynucleotides are identified as SEQ ID NOS: 85, 86.
Another transcription factor involved in the control of mammalian cell death is pur-alpha. Pur-alpha is a single-stranded DNA binding protein, which has been shown to play a role in both DNA replication and transcriptional regulation. Pur-alpha is able to suppress PCD of mammalian cells by two mechanisms. The first is the transcriptional repression of Fas (CD-95), a receptor which transduces a cell death signal by interaction with its ligand, and the second is the protection of mammalian cells against cell death mediated by p53. Polynucleotides encoding allelic variants of plant pur-alpha have been isolated (SEQ ID NOS: 90-91) from forestry species. The corresponding amino acid sequences of the pur-alpha polypeptides encoded by the polynucleotides are identified as SEQ ID NOS: 141-142.
The actual process of cell death involves the degradation of proteins and nucleic acids, mediated by proteases and nucleases. Experimental work done with mammalian systems suggests that prote
Flinn Barry
Lasham Annette
Genesis Research & Development Corporation Limited
McKelvey Terry
Sleath Janet
Speckman Ann W.
LandOfFree
Compositions affecting programmed cell death and their use... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Compositions affecting programmed cell death and their use..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compositions affecting programmed cell death and their use... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2859554