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Abstract

Genetic screens in Drosophila have uncovered a role for lipid phosphate phosphatases (LPPs) in regulating germ cell migration and survival. LPPs are transmembrane enzymes, localized to the cell surface with their catalytic domain facing outside of the cell. They are thereby able to dephosphorylate extracellular lipids such as lysophosphatidic acid and sphingosine 1-phosphate.
Recently we have uncovered a role for LPPs in heart development. LPPs are strongly expressed in Drosophila heart cells and in LPP mutants the heart is malformed. The Drosophila heart is a linear structure composed of inner cardioblast and outer pericardial cells. In mid-embryogeneis these cells form continuous rows on both sides of the embryo. In order to coalesce the heart cells contact the ectoderm and make use of dorsal closure events to move towards the midline and each other.
We have analysed the movement and morphology of heart cells in wild type and LPP mutants. In the mutant we find that the heart cells are specified properly and move towards the midline. In the majority of embryos the heart cells meet normally at the midline but in some embryos this is incomplete and small gaps remain. In both cases however the heart cells subsequently loose adhesion between rows generating a malformed heart.
Ongoing research in our lab is examining the morphology and behaviour of heart cells during heart formation. Our goal is to discern which and how lipids influence heart cell behaviour and if there is functional connection between their role in germ and heart cells.