Date of Award
2025
Document Type
Honors Thesis (Open Access)
Department
Colby College. Biology Dept.
Advisor(s)
Christina Cota
Second Advisor
Tariq Ahmad
Third Advisor
Yee Mon Thu
Abstract
Cell-to-cell adhesion is necessary for the proper establishment of epithelial tissues and organs during development. In vertebrate organisms, tight junctions comprised of Claudin, Occludin and Junctional Adhesion Molecule (JAM) transmembrane proteins anchor cells to one another and serve as physical barriers to the transport of molecules between epithelial cells, regulating the epithelial polarity and paracellular transport. In addition, Claudin proteins within tight junctions interact with the actin-binding protein Zona Occludin (ZO) to create a linkage between the cytoskeletons in adjacent cells. In the model chordate, Ciona robusta, Bipolar Tail Neurons (BTNs) undergo a complex morphogenesis during which newly specified pairs of BTNs delaminate from the dorsal ectoderm and migrate as pairs of cells anteriorly alongside the neural tube. RNA-seq profiling of BTNs has revealed that a putative tight junction protein, Claudin.j, is expressed when BTN cells are specified. However, whether Claudin.j participates in these structures is unknown and what role this may play in the morphogenesis of BTNs remains unclear. To determine whether Claudin.j is necessary to form a tight junction that links pairs of BTN cells during their collective migration, we examined the distribution of fluorophore-tagged Claudin.j, JAM and ZO in transgenic BTN cells, as well as Claudin.j expression in the whole Ciona body across developmental stages. To more directly assess whether Claudin.j might interact with ZO proteins to facilitate migration of BTN cell pairs, we also generate transgenic embryos expressing truncated Claudin.j proteins which lack the PDZ-binding domain required for binding to ZO. Our results are necessary for understanding the specific role of cell junction-associated proteins, such as Claudin.j, in the collective migration of neuronal cells.
Keywords
Claudin, Bipolar Tail Neuron (BTN), Ciona, Collective Migration, Tight Junction, Hybridization Chain Reaction (HCR)
Recommended Citation
Tchavyntchak, Olchey, "Characterizing the Role of Claudin.j in Bipolar Tail Neuron Migration" (2025). Honors Theses. Paper 1530.https://digitalcommons.colby.edu/honorstheses/1530