2010 - 19th Annual NC State Undergraduate Research Spring Symposium

Session Time : 4/22/10 12:15 PM - 4/22/10 1:30 PM

Content Area : Plant Biology

Student Presenters :
Austin Gray Wood Molecular and Structural Biochemistry

Mentors and/or Co-Authors :
Wendy Boss Plant Biology

Abstract Title : Nuclear Lipids and Their Impact on Plant Chromatin Structure

Abstract :
Phosphatidylinositol lipids have been studied extensively with regard to membranes and signaling pathways, but research to investigate their effects in the nucleus of plant cells is at an early stage. Mutation of a phosphatidylinositol phosphate kinase (PIPK) had a distinct effect on the chromatin structure in Drosophila melanogaster (Cheng and Shearn, Genetics 167:1213-23, 2004). PIPKs phosphorylate phosphatidylinositol phosphate (PtdInsP) to form the signaling lipid phosphatidylinositol bisphosphate (PtdInsP₂). In D. melanogaster, when Skittles, the gene that encodes the PIPK, was mutated there was a drastic increase in histone H1 hyperphosphorylation which lead to increased condensation of the chromosomes and inhibition of transcription of certain genes. We are examining the effect of increasing nuclear PtdInsP₂ on the chromatin structure of plants, in particular, Nicotiana tobacum. We have used a transgenic line of tobacco cells, which expresses human (Hs) PIPK1-α, a human PIPK. The transgenic HsPIPK cells and isolated nuclei have increased total of PtdInsP₂ which we hypothesized would lead to changes in chromatin structure. To test our hypothesis, we observed differences in BrdU incorporation of the two cell lines to determine DNA synthesis efficiency, and differences in the global modification of histones as an estimate of total chromatin state. The BrdU incorporation studies showed decreased incorporation of BrdU in HsPIPK cells compared to WT. Analysis of histone modifications indicate an increase in histone H3K9 dimethylation and a decrease in histone H3K9 acetylation in HsPIPK cells.