Identifying the Cellular Mechanisms By Which Porcn Regulates Neural Tube Closure

Proper development of the spinal cord is required for transmission of motor and sensory information to and from the brain and initiation of reflexes. Defects in this process can lead to structural neurological birth defects, such as spina bifida. The Wnt family of genes, codes for secreted signaling proteins. Wnt signals have vital roles in multiple phases of spinal cord development, including the closure of the neural plate to form the neural tube. Porcupine (Porcn), a predicted membrane bound O-acyl transferase (MBOAT), promotes the post-translational modification of Wnt proteins with lipid adducts and is required for Wnt function. The long-term objective of this project is to characterize the neural tube defects caused by Porcn inhibition, idenitfying the cellular mechanisms by which Porcn regulates neural tube closure. We hypothesize that Porcn is required for Wnt-dependent morphogenesis and proliferation during neural tube closure. To test this hypothesis, it is necessary to assay for proliferation, apoptosis, convergence and extension, and oriented cell division in control and Porcn RNAi embryos. The short-term goal of my project is to develop the methodologies for these assays. To date, I have successfully imaged HH ST 10-11 embryos stained for NCAM and DAPI in whole mount. These images show that staining for NCAM and DAPI is likely to be an effective way to observe cell shape change in Porcn deficient embryos. Future studies include extending these studies to include younger embryos. I also plan to immunostain with antibodies that recognize phosphohistone H3, a marker for proliferative cells.