Michael E. Greenberg, Ph.D.
Children's Hospital, Boston

The Role of P13K/Akt Dependent Phosphorylation of a Mammalian Fork Head Transcription Factor FKHRL1 in Cell Senescence and Organismal Aging.

We propose to study the importance of a cellular signaling pathway, termed the P13K/Akt/Daf16 pathway, for determining the life span of cells and multi-cellular organisms. Disruption of the P13K/Akt pathway has previously been shown to affect the life span of the invertebrate organism C. elegans, a nematode. We plan to extend these studies to mammals by developing strains of mice that bear mutations in components of this signaling cascade. The mutant mice will be analyzed to determine if disruption of the P13K/Akt/Daf16 pathway affects cell or organismal life-span. The focus of our research will be on the last protein in the signaling cascade-Daf16. The mammalian version of DAF16 is called FKHRL1. Our first objective will be to engineer mutations into FKHRL1 that will render it either highly active all the time, or alternatively mutations that will inhibit FKHRL1 function. Once mice are generated that bear these specific mutations we will examine how the mutations affect the life span of the mice. Since the P13K/Akt/Daf16 pathway has also been shown to control the proliferation and survival of cells we will also examine the mutant mice for alterations in cell proliferation and survival during development. One might expect that the mutations in FKHRL1 might lead to diseases such as cancer or cell death since the disruption of other components of the P13K/Akt pathway have previously been found to lead to these disorders. The second objective of our research will be to determine how FKHRL1 acts within cells. We have obtained evidence that FKHRL1 controls the expression of genes that may regulate cellular responses. Our goal will be to determine which of the 100,000 or more genes in the mammalian genome are targets of FKHRL1. Once the FKHRL1 targets are identified we plan to study their function and to determine how they contribute to aging as well as disease states such as cancer and neurological disorders.

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