Dr. Eric J. Wagner, Assistant Professor

Department of Biochemistry and Molecular Biology

University of Texas-Houston Medical School
MSB 6.172 Houston, Texas 77225
(713) 500-6124 - Fax (713) 500-0652
email:Eric.J.Wagner@uth.tmc.edu

Ph.D. Duke University
NIH Postdoctoral Fellow, Cottrell Postdoctoral Fellow, University of North Carolina at Chapel Hill
Pathway to Independence Award (NIGMS/NIH)

RNA METABOLISM THROUGHOUT THE CELL CYCLE

The regulation of RNA metabolism is a primary engine driving the temporal and tissue specific control of gene expression.  Targets of regulation can occur throughout the RNA maturation process taking place either in the nucleus or the cytoplasm.  As a model system, we study the regulation of histone mRNA metabolism.  The replication-dependent histone mRNA have, in lieu of a polyA tail, a conserved stem loop sequence at their 3’ end (Figure below). 

These mRNA are the only non-polyadenylated messages within the cell and are expressed primarily during S phase, to coincide with the replication of DNA. Given the unique nature of these messages, a specialized group of factors have evolved to govern their metabolism.  The focal member of this group of factors is the Stem Loop Binding Protein (SLBP), which binds the stem loop and is presumed to be involved at all stages of histone mRNA metabolism.  This would include its processing at the Cajal Bodies, which are nuclear substructures thought to be the site of histone transcription, histone mRNA export, translation, and its eventual decay (Figure below).  A second critical factor required for the processing reaction is the U7 snRNP.  This is a ribonucleoprotein complex containing several Sm and Lsm proteins as well as the U7 snRNA.  These factors, as well as several others receive regulatory cues from the cell-cycle machinery to allow for the accumulation of histone mRNA in S phase.  Moreover, in the event of halt to DNA replication (caused by DNA damage, stalled replication forks, etc.) histone mRNA is rapidly destroyed.

The goals of my laboratory are to understand the mechanism of how histone mRNA metabolism is regulated as a function of cell cycle progression.  To accomplish these goals, we use two complementary experimental systems:  mammalian cell culture/ in vitro assays and Drosophila cell culture/ fly genetics.

1.  Mammalian cells.  We use several human tissue culture cell lines including HeLa, U2OS, and 293T cells to study histone mRNA throughout the cell cycle.  SLBP is known to be expressed only during S phase while the U7 snRNP is thought to be ubiquitously expressed.  We use a combination of RNA interference and classical molecular biology to study the mechanisms of histone mRNA metabolism.

2.  Drosophila cells/ flies. Drosophila histone mRNA metabolism is regulated similar to humans having both a stem loop and SLBP involved as well as a U7snRNP.  We use a combination of genome-wide RNAi screening in S2 cells and P elements mutagenesis in flies to study histone mRNA.  In addition, the fly offers us an amenable cell biological system to study localization of histone pre-mRNA processing factors.  The figure below is staining for a U7snRNP component (red) in the Drosophila embryo.

Raw data for RNAi screen described in Chen et al, 2012

Marzluff WF, Wagner EJ, Duronio RJ.  (2008) Metabolism and regulation of replication-dependent histone mRNAs:  life without a polyA tail. Nature Reviews Genetics (in press).

Wagner EJ, Burch BD, Godfrey AC, Salzler HR, Duronio RJ, and Marzluff WF. (2007) A genome-wide RNA interference screen reveals that variant histones are necessary for replication-dependent histone pre-mRNA processing. Mol Cell, Nov 30: 28 (4): 692-699 (PMCID: 18042462)

Wagner E.J., & Marzluff (2006) ZFP100 is a Limiting Component of the U7snRNP that is Required for G1/S phase Transition. Mol Cell Biol Sep;26(17):6702-12. (PMCID: 16914750)

Wagner E.J., Ospina J., Dundr M., Matera A.G., Marzluff W.F. (2006) Conserved Zinc Fingers Mediate Multiple Functions of ZFP100, a U7 snRNP Associated Protein RNA Jul;12(7):1206-18. (PMCID: 16714279) 

Wollerton M.C., Gooding C.G., Wagner E.J., Garcia-Blanco M.A., Smith C.W.J. (2004).  Polypyrimidine Tract Binding Protein Autoregulates via Alternative Splicing of Exon 11. Mol Cell, 13(1):91-100. (PMCID: 14731397)

Wagner E.J., Garcia-Blanco M.A. (2002).  RNAi Mediated Depletion of PTB Leads to Enhanced Exon Definition.  Mol Cell, 10: 943-9. (PMCID: 12419237)

 Wagner E.J., Garcia-Blanco M.A. (2001).  Polypyrimidine Tract Binding Protein Antagonizes Exon Definition. Mol Cell Biol, 21: 3281-88. (PMCID: 11313454)

Search PubMed for a complete list of Dr. Wagner's publications.