Nontransformed T cells require IL-2 for proliferation, and IL-2Ralpha is an obligatory component of the high affinity biologically relevant IL-2R. Numerous studies have characterized the transcriptional up-regulation of IL-2Ralpha in mitogenically stimulated T cells. On the other hand, and of potential biological importance, post transcriptional control of IL-2Ralpha expression has yet to be adequately explored or definitively demonstrated. Data presented in this proposal clearly show that IL-2Ralpha expression is regulated at the translational level in primary T cells exposed to mitogenic stimuli. We show that increased translation of the IL-2Ralpha transcript is paralleled by the induction of IL-2 signaling pathways, and we suggest that translational up-regulation of IL-2Ralpha requires the activity of the cell cycle regulatory kinase, cdk2. Interestingly, we found that cdk2 expression was also controlled at a post- transcriptional level and, most likely, by a cdk2-dependent mechanism. These studies identify novel actions of cdk2 and suggest that previously unrecognized mechanisms contribute to the expression of IL-2Ralpha and cdk2. We also present data showing that cdk2 activation and IL-2 signaling are interdependent processes in splenic T cells. We suggest that cdk2 activity is required for the efficient translation of IL-2R and that signals generated by the IL-2R facilitate cdk2 activation by maintaining the down-regulation of the cdk2 inhibitor, P27kip1. These interactions and the involvement of cdk2 in the translation of two important cell cycle regulatory molecules - IL-2Ralpha and cdk2 itself - form the focus of our proposal. Specifically, we will examine potential mechanisms by which cdk2 activity might control the translation of IL-2Ralpha in primary splenocytes. We will identify the region of the 5' untranslated region of the IL-2Ralpha mRNA that is responsible for translational regulation and will determine if proteins bind to this region in a manner dependent on cdk2 activity. We will also determine if cdk2 activity modulates the synthesis or the stability of cdk2. Additional experiments will assess the contribution of IL-2 signaling to the continued down-regulation of p27kip1 in TCR-activated splenocytes. Lastly, the mechanism by which TCR activation promotes the expression of cyclin A will be delineated.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA093544-02
Application #
6620586
Study Section
Special Emphasis Panel (ZRG1-PTHC (01))
Program Officer
Mccarthy, Susan A
Project Start
2002-02-07
Project End
2006-12-31
Budget Start
2003-01-09
Budget End
2003-12-31
Support Year
2
Fiscal Year
2003
Total Cost
$258,100
Indirect Cost
Name
University of South Florida
Department
Biochemistry
Type
Schools of Medicine
DUNS #
069687242
City
Tampa
State
FL
Country
United States
Zip Code
33612
Bagui, Tapan K; Cui, Dongming; Roy, Sangita et al. (2009) Inhibition of p27Kip1 gene transcription by mitogens. Cell Cycle 8:115-24
Mohapatra, Subhra; Chu, Baoky; Zhao, Xiuhua et al. (2009) Apoptosis of metastatic prostate cancer cells by a combination of cyclin-dependent kinase and AKT inhibitors. Int J Biochem Cell Biol 41:595-602
Roy, Sangita; Shor, Audrey C; Bagui, Tapan K et al. (2008) Histone deacetylase 5 represses the transcription of cyclin D3. J Cell Biochem 104:2143-54
Mohapatra, Subhra; Coppola, Domenico; Riker, Adam I et al. (2007) Roscovitine inhibits differentiation and invasion in a three-dimensional skin reconstruction model of metastatic melanoma. Mol Cancer Res 5:145-51
Shor, Audrey C; Keschman, Elizabeth A; Lee, Francis Y et al. (2007) Dasatinib inhibits migration and invasion in diverse human sarcoma cell lines and induces apoptosis in bone sarcoma cells dependent on SRC kinase for survival. Cancer Res 67:2800-8
Mohapatra, Subhra; Chu, Baoky; Zhao, Xiuhua et al. (2005) Accumulation of p53 and reductions in XIAP abundance promote the apoptosis of prostate cancer cells. Cancer Res 65:7717-23
Mohapatra, Subhra; Chu, Baoky; Wei, Sheng et al. (2003) Roscovitine inhibits STAT5 activity and induces apoptosis in the human leukemia virus type 1-transformed cell line MT-2. Cancer Res 63:8523-30