The overall objective of the work proposed in this application and accomplished during the past 29 years the grant has been active is to define and understand the mechanisms regulating the growth of gastrointestinal tract mucosa. This objective is unaltered in the current proposal, which focuses on determining the mechanisms of action of polyamines on the growth of intestinal epithelial cells. The PI will test the principal hypothesis that polyamines are actively involved in regulating signal transduction pathways that determine whether cells progress through the cell cycle, undergo cell cycle arrest, or undergo apoptosis. This novel hypothesis is a major shift in thinking about polyamine action. In the past, numerous studies demonstrated that in polyamine depleted cells various activities of the cell were depressed. In other words, """"""""things"""""""" failed to occur. The PI's studies of the past 3 years, however, indicate that the absence of polyamines stimulates or activates pathways resulting in changes of cell function. Their data indicate that polyamine depleted IEC-6 cells are actively shifted into GI cell cycle arrest and that apoptosis is inhibited. These data will be expanded and their hypothesis tested by examining the mechanisms behind these events by determining the role of polyamines in the regulation of the cell cycle. The PI has proposed a total of eleven specific aims organized into 3 specific areas. The PI will examine the role of the Ras/MAPK cascade in cell cycle arrest induced by polyamine depletion, determine whether polyamines affect the levels and activities of cell cycle regulatory proteins, and use p53 mutated cell lines to elucidate the role of p53 in the cell cycle arrest caused by depletion of polyamines. Next, the PI will investigate the role of polyamines in apoptosis by determining whether polyamines protect cells from apoptosis regardless of the stimulus and by determining whether polyamine depletion alters the upstream regulators of caspase activity. The PI will then elucidate the roles and significance of NF-kappaB, STAT-3, p53 and the bcl-2 family of proteins in the anti-apoptotic response to polyamine depletion. These experiments will define the mechanisms resulting in cell cycle arrest in response to polyamine depletion and indicate their points of interaction with pathways that prevent apoptosis. The finding that normal polyamine levels are required for apoptosis is new and of great potential clinical significance, for it suggests a way to protect normal cells during cancer therapy. The basic knowledge gained from these studies will increase our understanding of mucosal healing and of any condition in which GI mucosal growth is altered or involved.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK016505-30
Application #
6380377
Study Section
Special Emphasis Panel (ZRG1-ALTX-1 (02))
Program Officer
May, Michael K
Project Start
1977-12-01
Project End
2005-03-31
Budget Start
2001-04-01
Budget End
2002-03-31
Support Year
30
Fiscal Year
2001
Total Cost
$392,090
Indirect Cost
Name
University of Tennessee Health Science Center
Department
Physiology
Type
Schools of Medicine
DUNS #
941884009
City
Memphis
State
TN
Country
United States
Zip Code
38163
Ray, Ramesh M; Bavaria, Mitul; Johnson, Leonard R (2015) Interaction of polyamines and mTOR signaling in the synthesis of antizyme (AZ). Cell Signal 27:1850-9
Bhattacharya, Sujoy; Ray, Ramesh M; Johnson, Leonard R (2014) Cyclin-dependent kinases regulate apoptosis of intestinal epithelial cells. Apoptosis 19:451-66
Ray, Ramesh M; Bhattacharya, Sujoy; Bavaria, Mitul N et al. (2014) Spermidine, a sensor for antizyme 1 expression regulates intracellular polyamine homeostasis. Amino Acids 46:2005-13
Ray, Ramesh M; Johnson, Leonard R (2014) Regulation of intestinal mucosal growth by amino acids. Amino Acids 46:565-73
Bavaria, Mitul N; Jin, Shi; Ray, Ramesh M et al. (2014) The mechanism by which MEK/ERK regulates JNK and p38 activity in polyamine depleted IEC-6 cells during apoptosis. Apoptosis 19:467-79
Ray, Ramesh M; Bhattacharya, Sujoy; Bavaria, Mitul N et al. (2014) Antizyme (AZ) regulates intestinal cell growth independent of polyamines. Amino Acids 46:2231-9
Bhattacharya, Sujoy; Chaum, Edward; Johnson, Dianna A et al. (2012) Age-related susceptibility to apoptosis in human retinal pigment epithelial cells is triggered by disruption of p53-Mdm2 association. Invest Ophthalmol Vis Sci 53:8350-66
Ray, Ramesh M; Li, Chunying; Bhattacharya, Sujoy et al. (2012) Spermine, a molecular switch regulating EGFR, integrin ýý3, Src, and FAK scaffolding. Cell Signal 24:931-42
Ray, Ramesh M; Viar, Mary Jane; Johnson, Leonard R (2012) Amino acids regulate expression of antizyme-1 to modulate ornithine decarboxylase activity. J Biol Chem 287:3674-90
Bhattacharya, Sujoy; Ray, Ramesh M; Chaum, Edward et al. (2011) Inhibition of Mdm2 sensitizes human retinal pigment epithelial cells to apoptosis. Invest Ophthalmol Vis Sci 52:3368-80

Showing the most recent 10 out of 62 publications