Characterizing the role of Canoe as a cell junction-cytoskeletal linker protein during Drosophila morphogenesis

Adherens junctions (AJs) connect epithelial cells to one another and connect the plasma membrane to the actomyosin cytoskeleton; this organization translates contractility to neighboring cells and preserves tissue integrity during morphogenesis. The exact interactions among adhesion molecules located at AJs remain unclear. It is currently thought that cadherins mediate cell-cell adhesion, while proteins bound to their cytoplasmic tails, known broadly as catenins, interact with junction-linker proteins. These linker proteins, in turn, interact with the actomyosin cytoskeleton. We examined whether Canoe acts as a junction-linker protein by testing its role in maintaining epithelial integrity, which is an indicator of junctional integrity. We used immunofluorescence and confocal microscopy to examine Drosophila melanogaster embryos during dorsal closure. In wild-type embryos, Canoe is enriched at the leading-edge epidermis and at multicellular junctions along the lateral epidermis. This enrichment pattern aligns closely with the location of actin filaments and myosin II heavy chain. We used RNA interference in conjunction with the UAS-Gal4 system to reduce canoe function. Loss of canoe caused cells along the lateral epidermis to become highly variable in shape, suggesting that translation of contractility to AJs occurred unevenly among the cell population. Furthermore, the number and regularity of puncta of Enabled, an actin assembly and elongation factor usually enriched at AJs, decreased along the leading edge. These results support the hypothesis that Canoe acts as a linker protein, playing an essential role in regulating epithelial sheet integrity and contractility. Understanding these complex interactions can provide insight into the mechanisms of wound healing and neural tube closure in humans and guide the creation of embryonic defect prevention therapies.Bachelor of Scienc

Acute worsening of CADASIL in a patient with COVID-19 infection: illustrative case

BACKGROUND: Reports of cerebrovascular ischemia and stroke occurring as predominant neurological sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which causes coronavirus disease 2019 (COVID-19), are increasingly evident within the literature. While various pathophysiological mechanisms have been postulated, including hypercoagulability, endothelial invasion, and systemic inflammation, discrete mechanisms for viral neurotropism remain unclear and controversial. OBSERVATIONS: The authors present a unique case study of a 64-year-old male with acute COVID-19 infection and acute worsening of previously stable cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a rare heritable arteriopathy due to mutation in the Notch3 gene, which is critical for vascular development and tone. Delayed cranial neuropathies, brainstem fluid-attenuated inversion recovery signal, and enhancement of olfactory and vagus nerves on magnetic resonance neurography in this patient further support viral neurotropism via cranial nerves in addition to cerebral vasculature. LESSONS: To the authors\u27 knowledge, this is the first case in the literature that not only demonstrates the consequences of COVID-19 infection in a patient with altered cerebrovascular autoregulation such as CADASIL but also highlights the tropism of SARS-CoV-2 for (1) cranial nerves as a mode of entry to the central nervous system and (2) vessels as a cause of cerebrovascular ischemia