PMA Treatment Results In Skeletal Defects And Skeletogenic Cell Mispatterning
Date
2022-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
In the sea urchin, the primary mesenchymal cells (PMCs) are the only cells that
give rise to the larval skeleton. They go through epithelial to mesenchymal transition
(EMT) to ingress into the body cavity, undergo cell fusion, receive chemotactic cues to
migrate anteriorly and synthesize the larval skeleton. Thus, the PMCs are a great model
to examine cellular properties of eukaryotic cells critical for the construction of
embryonic structure. To examine the effect of PKC activator phorbol 12-myristate 13-
acetate (PMA) in skeletogenesis at key developmental milestones of PMCs, we
implemented acute treatments of PMA during PMC ingression and anterior migration,
as well as prolonged treatment throughout development. Results indicate that PMA
treatment led to shortened dorsoventral connecting rods (DVC) of the primary skeleton,
ectopic skeletal branching and ectopic body rods of the secondary skeleton, as well as
mispatterned skeletogenic cells. To identify the molecular mechanism of how PMA
results in skeletal defects, we examined the spatial and temporal expression of genes
known to regulate skeletal patterning. Results indicate that PMA treatment shifts the
expression domain of Vegf3, which is an important chemotactic ligand received by the
PMCs. We also quantitatively determined that PMA treatment increases gene
expression of Vegf3 and biomineralization targets such as SM30 and SM50. Since PMA
has been shown to regulate additional pathways, including ERK/JNK through
downstream signaling of MAPK, we also examined the expression levels of these
transcripts. Results indicate that MAPK is significantly decreased in the PMA treated
embryos compared to the control, suggesting that this pathway may be suppressed by
PMA. Elucidating the molecular pathway behind regulation of cell motility and patterning through PMA contributes to our understanding of directed migration and cell
to cell communication, which are critical for forming proper embryonic structures in the
developing embryo.
Description
Keywords
Primary mesenchymal cells, Sea urchin, Embryo, Skeleton