An analysis of the requirement for septate junction proteins in essential morphogenetic events

Abstract

Proper organismal development depends upon highly regulated cellular rearrangements and cell shape changes that are driven by intrinsic stabilizing and dynamic forces within an epithelium. These morphological processes require coordination of signaling pathways, cytoskeletal changes, and cell adhesion. To identify essential regulators of morphogenesis, our lab conducted three screens to identify genes involved in regulating morphogenesis. From this screen, we identified a novel component of the septate junction (SJ), Macroglobulin complement related (Mcr). The SJ provides a barrier between epithelial cells to regulate paracellular flow, allowing for organ compartmentalization. The SJ requires over twenty proteins for its organization and function. While the function of the SJ is of critical importance to development and homeostasis, its role in morphogenesis was unclear. We examined whether the identification of Mcr in a screen for morphogenesis was an isolated role of Mcr or a concerted requirement for the entire SJ complex. To explore this question, we conducted an analysis of nine SJ genes and examined the penetrance of defects in head involution, dorsal closure, and salivary gland organogenesis. From this analysis, we determined that each SJ component examined has an essential role in regulating morphogenesis by contributing to cell shape changes and rearrangements.