Compositions and methods for mediating cell cycle progression

Abstract

Hypercellular nonhuman organisms have functionally inactivated expression of a cyclin inhibitor gene, especially p27. The growth rate of nonhuman organisms are increased such that a desired size is attained more quickly than as compared to nonvariant organisms. Inhibitors of the p27 cyclin dependent kinase inhibitor protein or sequences encoding the protein modulate vertebrate cell cycle progression and increase the proportion of dividing cells to non-dividing cells in a population of treated cells. As the proportion of dividing cells increases, the cell population, e.g., hematopoietic progenitor (stem) cells, is more efficiently used for gene therapy applications. Transgenic animals and plants, and knockout alleles are provided.

1 . A method for producing a hypertrophic variant organism, comprising functionally inactivating expression of a cyclin inhibitor gene in an organism wherein a hypertrophic variant is produced, the hypertrophy being relative to an organism having the functional cyclin inhibitor gene. 
     
     
         2 . The method of  claim 1 , wherein the cyclin inhibitor gene is a p27 gene. 
     
     
         3 . The method of  claim 1 , wherein the genome of said hypertrophic variant organism comprises a structurally disrupted cyclin inhibitor gene. 
     
     
         4 . The method of  claim 1 , wherein an antisense polynucleotide functionally inactivates expression of the cyclin inhibitor gene in the organism. 
     
     
         5 . The method of  claim 1 , wherein the functionally inactivated cyclin inhibitor gene is structurally disrupted by homologous recombination with a targeting construct. 
     
     
         6 . A polynucleotide targeting construct comprising a sequence that is homologous to a sequence present in a cyclin inhibitor gene and which, when integrated at the corresponding cyclin inhibitor gene locus, functionally inactivates cyclin inhibitor protein expression. 
     
     
         7 . A polynucleotide targeting construct of  claim 6 , wherein said cyclin inhibitor gene is a p27 gene. 
     
     
         8 . A hypertrophic nonhuman organism having a functionally inactivated cyclin inhibitor gene, the hypertrophy being relative to an organism having the functional cyclin inhibitor gene. 
     
     
         9 . The nonhuman organism of  claim 8 , wherein the cyclin inhibitor gene is a p27 gene. 
     
     
         10 . The hypertrophic nonhuman organism of  claim 8 , which is a plant. 
     
     
         11 . The hypertrophic nonhuman organism of  claim 8 , which is a mammal, fish or bird. 
     
     
         12 . A method for increasing the growth rate of an nonhuman organism, comprising functionally inactivating expression of a cyclin inhibitor gene in an organism wherein the growth rate of the organism is increased relative to an organism of the same species having the functional cyclin inhibitor gene. 
     
     
         13 . The method of  claim 12 , wherein the nonhuman organism is a plant. 
     
     
         14 . The method of  claim 12 , wherein the nonhuman organism is a mammal, fish or bird. 
     
     
         15 . The method of  claim 14 , wherein the nonhuman mammal is a pig, cow, goat, sheep, rabbit, or mouse. 
     
     
         16 . A method for increasing the proportion of dividing cells in a vertebrate cell population comprising:
 exposing said population of cells to a p27 inhibitor in an amount sufficient to increase the proportion of dividing cells to non-dividing cells relative to said proportion in a population of untreated cells.   
     
     
         17 . The method according to  claim 16 , wherein the cell population comprises fibroblasts, osteoblasts, myeloblasts, neurons, epithelial cells or hematopoietic progenitor cells. 
     
     
         18 . A method for increasing the efficiency of transducing a vertebrate cell population with a viral vector encoding a gene product of interest, comprising:
 exposing said population of cells to a p27 inhibitor in an amount sufficient to increase the proportion of dividing cells to non-dividing cells relative to said proportion in a population of untreated cells, and   contacting said exposed cells to a viral vector encoding the gene product of interest.   
     
     
         19 . The method according to  claim 18 , wherein the vertebrate cell is a mammalian hematopoietic progenitor cell. 
     
     
         20 . A p27 inhibitor which comprises an oligonucleotide that specifically binds to DNA encoding p27 or RNA transcribed therefrom and inhibits expression of p27 protein.