Xiangjian Zheng, Ph.D.,
Medical College of Georgia

Xiangjian Zheng is a postdoc in the laboratory that is interested in mechanisms of lipid signaling transduction. In particular, the regulation of phospholipase D (PLD), which is one of the key enzymes involved in phospholipid metabolism. PLD catalyzes the hydrolysis of phosphatidylcholine to generate phosphatidic acid (PA) and choline. PA and its metabolites, diacylglycerol (DAG) and lysophosphatidic acid (LPA), have been shown to be involved in multiple physiological events, including cell proliferation, transformation and migration. In addition to the hydrolysis, PLD can also catalyze, in the presence of primary alcohol, a transphosphatidylation reaction to generate phosphatidylalcohol. In work from his previous lab, he found that PLD can utilize glycerol, a physiological primary alcohol, to produce phosphatidylglycerol, which has been shown to activate downstream protein kinases and affect protein complexes formation in cell membranes. Two isoforms of mammalian PLDs, PLD1 and PLD2 have been characterized. However, the functional differences between these two isoforms are not clear. One of his current projects is to study the lipid substrates and products differences between PLD1 and PLD2 in living cells using lipidomics approaches. Another ongoing project is to study the lipid profiles in colon carcinogenesis, particularly the PLD-mediated signal transduction pathway in cancer cell proliferation and migration. Future plans include looking at the role of PLD isoforms in zebrafish development.