Paul W. Huber

Paul Huber 344 336

Professor, Department of Chemistry & Biochemistry

Phone: 574-631-6042

Office: 437 Stepan Chemistry Hall

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RNA localization. The body plan of the frog (Xenopus laevis) begins to be determined in the oocyte due to the nonrandom positioning of certain mRNA's that are transported to either ends of the cell. Localization is achieved by the formation of protein complexes on distinct regions (localization elements) of the mRNA that engage motor proteins for movement along the cytoskeleton. Considerable progress has been made identifying the proteins that comprise these ribonucleoprotein (RNP) complexes; however, little is known about the functions of the individual proteins, including those that determine the ultimate location of the RNA. We have identified several of the proteins that bind to the RNAs that move to the vegetal cortex (Vg1 mRNA) and have constructed an interaction map for many of these proteins. Current efforts include identification of the remaining proteins of the RNP complex and determining their overall stoichiometry using mass spectrometry. Through an analysis of RNP complexes that form on RNAs that move to the animal hemisphere, we hope to understand how direction of movement is determined.

Developmental proteomics. Advances in modern mass spectrometry, especially the introduction of stable isobaric tags (iTRAQ) to label complex peptide digests, has enabled the relative quantification of proteins in small sample sizes. We have been using iTRAQ analysis to examine the changes in protein expression during the early stages of Xenopus development. In a single experiment well over 6,000 proteins have been identified and their relative amounts tracked over several developmental stages. These experiments are providing insight into the regulation of temporal protein expression that is critical for the complex process of embryo development.

SUMOylation and heart development. Post-translational modification of proteins by conjugation to the small polypeptide SUMO regulates a wide variety of biological processes. There is considerable evidence that problems with SUMOylation activity underlie many instances of congenital heart disease (CHD). Indeed, several of the transcription factors that regulate heart development are targets of this post-translational modification. We have created transgenic Xenopus in which SUMOylation activity is depleted specifically in cardiac tissue with the result that these frogs exhibit many of the defects seen in CHD. These hearts are being used for proteomic and genomic analysis in order to understand how SUMO contributes to the proper development of the heart.

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