The Role of Calcium Signaling in Zebrafish Brain Morphogenesis
Mentor 1
Dr. Jennifer Gutzman
Location
Union Wisconsin Room
Start Date
29-4-2016 1:30 PM
End Date
29-4-2016 3:30 PM
Description
Cell shape changes in the developing brain epithelium lead to specific tissue folds that subsequently determine the shape of the vertebrate brain. Misregulation of these cell shape changes can lead to neural tube defects or abnormal brain morphology. Our lab uses the well characterized and highly conserved zebrafish midbrain-hindbrain boundary (MHB) as a model to determine the mechanisms that regulate brain morphogenesis. Cell shapes are mediated by mechanical forces exerted by motor proteins, most notably the non-muscle myosins (NMII). We previously demonstrated that non-muscle myosin IIA (NMIIA) and non-muscle myosin IIB (NMIIB) differentially regulate cell length and cell width respectively during vertebrate brain morphogenesis. However, the upstream signals that result in NMII activation in this context are not known. We hypothesized that intracellular calcium may act as an upstream mediator of NMII activity to regulate brain morphogenesis. We tested this hypothesis using pharmacological manipulation of intracellular calcium levels in the developing embryo. We analyzed cell shape changes and NMII activity following manipulation of intracellular calcium levels. We found that inhibition of calcium, by blocking calcium release from the endoplasmic reticulum, resulted in abnormally long cells at the MHB. In contrast, increasing intracellular calcium levels resulted in abnormal decreases in epithelial cell length at the MHB. We further hypothesized that these effects on cell shape were mediated by calcium activation of NMII. We analyzed NMII activity by Western blotting for phosphorylated myosin regulatory light chain (pMRLC) and found that increased intracellular calcium levels resulted in an increase in pMRLC.
The Role of Calcium Signaling in Zebrafish Brain Morphogenesis
Union Wisconsin Room
Cell shape changes in the developing brain epithelium lead to specific tissue folds that subsequently determine the shape of the vertebrate brain. Misregulation of these cell shape changes can lead to neural tube defects or abnormal brain morphology. Our lab uses the well characterized and highly conserved zebrafish midbrain-hindbrain boundary (MHB) as a model to determine the mechanisms that regulate brain morphogenesis. Cell shapes are mediated by mechanical forces exerted by motor proteins, most notably the non-muscle myosins (NMII). We previously demonstrated that non-muscle myosin IIA (NMIIA) and non-muscle myosin IIB (NMIIB) differentially regulate cell length and cell width respectively during vertebrate brain morphogenesis. However, the upstream signals that result in NMII activation in this context are not known. We hypothesized that intracellular calcium may act as an upstream mediator of NMII activity to regulate brain morphogenesis. We tested this hypothesis using pharmacological manipulation of intracellular calcium levels in the developing embryo. We analyzed cell shape changes and NMII activity following manipulation of intracellular calcium levels. We found that inhibition of calcium, by blocking calcium release from the endoplasmic reticulum, resulted in abnormally long cells at the MHB. In contrast, increasing intracellular calcium levels resulted in abnormal decreases in epithelial cell length at the MHB. We further hypothesized that these effects on cell shape were mediated by calcium activation of NMII. We analyzed NMII activity by Western blotting for phosphorylated myosin regulatory light chain (pMRLC) and found that increased intracellular calcium levels resulted in an increase in pMRLC.
