Aomori University

Cell polarity directs the orientation and size of asymmetric cell division and the segregation of cell fate determinants, processes fundamental to development in all multicellular organisms. During asymmetric cleavage, the mitotic spindle aligns with a specified polarity of the mother cell, and cell fate determinants are distributed asymmetrically along the division axis. Here, we report that pharmacological inhibition of serotonin signaling during the 4-to-8-cell division in early embryos of the mud snail Ilyanassa obsoleta (currently known as Tritia obsoleta) disrupts the typical unequal division pattern. The oblique axis of division common to spirally cleaving molluscan embryos is altered, and the position of the mitotic spindle is randomized in these treatments. Mother cells generate abnormally large, atypically positioned daughter cells. We also find that, in normal embryos, proteins recognized by phosphorylated PKC and Bazooka/PAR-3 antibodies typically co-localize with the spindle apparatus to the apical cortex of each mother cell. These antigens subsequently segregate to the smaller of the two daughter cells. In embryos treated with the serotonin-receptor antagonist, the localization of these asymmetrically segregating proteins is randomized, and their localization is independent of spindle position. These results suggest that serotonin signaling coordinates spindle orientation, cortical polarity, and cell size in early asymmetric cleavages.

Neuronal adhesion is regulated by interactions between neurons and the extracellular matrix and plays a critical role in neural development. Chondroitin sulfate proteoglycans (CSPGs), key structural components of the extracellular matrix in the nervous system, are involved in various processes including neuronal migration, neurite outgrowth, and axonal regeneration. The diverse functions of CSPGs are controlled by the sulfated structures of chondroitin sulfate (CS) polysaccharides. In this study, we found that CS-E, a highly sulfated CS polysaccharide, but not CS-A, CS-B, CS-C, or CS -D, induced the formation of neuronal aggregates in primary cortical cells with features of immature neurons. This effect is likely due to the unique properties of CS-E, which altered cell adhesion to the coated surface of culture coverslips, leading to cell detachment and subsequent aggregate formation. Pharmacological and phosphorylation analyses aimed at elucidating signaling cascades revealed that the VEGF receptor is a cell surface target of CS-E, and subsequent activation of the Akt/GSK3β pathway plays a crucial role in aggregate formation. The c-Raf/GSK3β pathway is also involved in CS-E-induced aggregate formation. Furthermore, actin polymerization and the organization of the F-actin cytoskeleton, which are mediated through activation of the Akt/GSK3β pathway, were required for CS-E-induced aggregate formation. In summary, CS-E regulates neuronal adhesion by activating the VEGF receptor/Akt/GSK3β pathway. The identification of signaling cascades involving CS-E may provide insights into the mechanisms underlying neuronal development.

The influenza split vaccine (ISV) is generally administered without adjuvant via intra-muscular (i.m.) or intranasal route. Research has demonstrated that SV alone exhibits no capacity to elicit a Th1 (T helper-1) response and cellular immunity represented by cytotoxic T lymphocytes (CTL) induction. This finding is consistent with the observation that SV merely up-regulates antibody (Ab) production in the pre-disposed population. This tendency is reproduced in the SV model in conjunction with conventional adjuvants, including alum or squalene. These adjuvants amplify the Th2 shift, consequently stimulating Th2-dependent Ab production in mice. Conventional adjuvants, when employed with SV in animal studies, demonstrate a limited capacity to stimulate cellular immune activation. The present study aims to demonstrate the efficacy of a Th1-inducing adjuvant, ARNAX, in promoting antigen-presenting DC and subsequent Ag-specific CTL proliferation, culminating in Th1 polarization. Consequently, the synthesis of the two effectors, CTL and Ab, is augmented by the incorporation of ARNAX in SV. The enhanced SV-mediated protective immunity may be further augmented by the induction of antigen-specific CTL and the unique profile of Th1-mediated Ab production.