PRUITT, Kevin
Feist-Weiller Cancer Center Physiology
4-219/Medical School
Phone: 318-675-8351
Fax: 318-675-7393
Email: kpruitt2@jhmi.edu

Bio

Assistant Professor, Department of Molecular and Cellular Physiology and the Feist-Weiller Cancer Center, LSU Health Sciences Center (2006 -)

Johns Hopkins Univesity School of Medicine & Sidney Kimmel Comprehensive Cancer Center, ACS Postdoctoral Fellow, (2002-2006)

University of North Carolina at Chapel Hill, Chapel Hill, NC, Department of Pharmacology, Ph.D (2001), NSF Predoctoral Fellow (1997-2000)

University of Texas at Austin, Austin, TX, B.S., Chemical Engineering (1995)

 

Recent Publications:

   Pruitt K, Zinn, RL, Ohm, JE, McGarvey, KM, Kang, SL, Watkins, DN, Herman JG, Baylin, SB (2006) Inhibition of SIRT1 reactivates silenced cancer genes without loss of promoter DNA hypermethylation PLoS Genetics 2(3): e40.

   Pruitt K, Ulku A, Frantz K, Rojas R, Muniz-Medina V, Rangnekar VM, Der CJ, Shields JM (2005).  Ras-mediated loss of the pro-apoptotic response protein Par-4 is mediated by DNA hypermethylation through Raf-independent signaling cascades. J Biol Chem 280 (17) 13363-23370.

 

Research Interests

1.  What role does SIRT1 play in epigenetic silencing of anti-tumor genes?  An important theme in cancer biology that has emerged within the last decade highlights the role that aberrant epigenetic regulation plays in tumor suppressor gene silencing (TSG).  One of the key mediators of TSG silencing is the SIRT1 deacetylase which has been shown to be important for regulation of lifespan in a number of model organisms.  Recently, we reported that SIRT1 mediates heterochromatin formation and heritable silencing of endogenous TSGs in several cancer types.  A major interest of our group is to identify novel tumor suppressor genes silenced by SIRT1.

2.  What is the mechanism by which SIRT1 regulates gene silencing?  Though it is well established that DNA hypermethylation of promoter regions of genes is linked with transcriptional regulation, it is unclear how DNA methylation is linked with the initiation and propagation of epigenetic silencing mechanistically.  We demonstrated that SIRT1 localizes to promoters of several aberrantly silenced TSGs in which 5'CpG islands are densely hypermethylated but not to these same promoters in cell lines where the promoters are not hypermethylated and the genes are expressed.  Additionally, it is not known how specific promoters of TSGs are targeted to establish an aberrant pattern of methylation or what factors are required to maintain this methylation pattern once it has been established.  This observation has major implications for the identification of novel anti-cancer therapies, thus we are very excited about elucidating this mechanism of gene silencing and defining the protein complexes mediating TSG repression.

3.  How does SIRT1 regulate Wnt signaling?  Wnt and beta-catenin signaling pathways have been shown to be the frequently deregulated in a wide range of cancers.  We were the first to demonstrate that SIRT1 is a key mediator of the aberrant silencing of the Wnt antagonists and regulator of Wnt signal transduction.  Additionally, we demonstrated that SIRT1 regulates the expression of beta-catenin responsive genes such as cyclin D1 and beta-catenin binding partners such as E-cadherin.  Because Wnt signaling is important for not only cancer biology but developmental biolgy as well, we are excited about defining the connection between SIRT1 and Wnt signaling at multiple levels.

Specialized Techniques/Procedures

1.  Chromatin Immunoprecipitation

2.  Retroviral based RNA interference

3.  Retroviral Infection

4.  PCR, RT-PCR

5.  Methylation Specific PCR (MSP)

6.  Bisulfite Sequencing

7.  Western Blotting

8.  Immunoprecipitation

9.  Site-Directed Mutagenesis

10.  Deacetylase Enzymatic Assays