Distinct intracellular Ca2+ dynamics regulate apical constriction and differentially contribute to neural tube closure

Abstract

Early in the development of the central nervous system, progenitor cells undergo a shape change, called apical constriction, that triggers the neural plate to form a tubular structure. How apical constriction in the neural plate is controlled and how it contributes to tissue morphogenesis are not fully understood. In this study, we show that intracellular calcium ions (Ca²⁺) are required for Xenopus neural tube formation and that there are two types of Ca²⁺-concentration changes, a single-cell and a multicellular wave-like fluctuation, in the developing neural plate. Quantitative imaging analyses revealed that transient increases in Ca²⁺ concentration induced cortical F-actin remodeling, apical constriction and accelerations of the closing movement of the neural plate. We also show that extracellular ATP and N-cadherin (cdh2) participate in the Ca²⁺-induced apical constriction. Furthermore, our mathematical model suggests that the effect of Ca²⁺ fluctuations on tissue morphogenesis is independent of fluctuation frequency and that fluctuations affecting individual cells are more efficient than those at the multicellular level. We propose that distinct Ca²⁺ signaling patterns differentially modulate apical constriction for efficient epithelial folding and that this mechanism has a broad range of physiological outcomes.

Keywords: Actomyosin; Apical constriction; Ca2+; Epithelial remodeling; Neural tube closure.