Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Jira White - Claflin University
Co-Author(s): Benjamin Tajer, University of Pennsylvania, Philadelphia, Pennsylvania; Mary C. Mullins, University of Pennsylvania, Philadelphia, Pennsylvania
Bone Morphogenetic Protein (BMP) signaling patterns the dorsal-ventral axis during early embryonic development. The dimeric BMP ligand brings together two type I and two type II receptors to signal. The type II receptors then phosphorylate the type I receptors, which in turn phosphorylate and activate Smad transcription factors. Recent studies have shown that dorsal-ventral patterning requires a complex containing two different type I receptors, Acvr1 and Bmpr1, yet the roles of the Acvr2 type II receptors in this complex remain uncharacterized. Murine gastrulation requires Acvr2, but this process involves Nodal and BMP ligands both of which bind Acvr2, confounding the role of Acvr2 receptors in early development. Zebrafish phenotypes for Nodal and BMP deficiencies are distinct, allowing us to separate the role of Acvr2 in these pathways. To explore these roles, we have developed mutants for each of the four zebrafish Acvr2 receptors. Though all Acvr2 single mutants present with a wild-type phenotype, combining these mutants through crosses reveals a variety of loss of function phenotypes. Acvr2ba and Acvr2bb play the largest roles, with zygotic acvr2ba;acvr2bb double mutants having a mildly dorsalized phenotype. While acvr2aa;acvr2ab double mutants have no phenotype, they do contribute to dorsoventral patterning, as the quadruple mutants are severely dorsalized. We have also observed some variability between embryos of the same zygotic genotype, which may be due to maternal contribution. We aim to further characterize the maternal and zygotic contributions of each Acvr2 receptor through further crosses, morpholino knockdowns, and RNA rescue experiments.
Funder Acknowledgement(s): National Institute of Health
Faculty Advisor: Mary C. Mullins, firstname.lastname@example.org
Role: I analyzed CRISSPER knockout alleles for the 4 Acvr2 receptors in Zebrafish to determine the role Acvr2 plays in embryonic axial patterning. I genotyped over three-hundred fish for five different mutant alleles, to identify fish containing useful genotypes for crosses. I genotyped and analyzed hundreds of embryos from those crosses to determine the roles that each of the Acvr2 receptors play in embryonic axial patterning. I also synthesized Acvr2 receptor RNA, performed injection experiments in early embryos, and performed in-situ hybridization experiments to mark bmp signaling.