Mapping calcium dynamics in a developing tubular structure

Abstract

Calcium is a ubiquitous and versatile second messenger that plays a central role in the development and function of a wide range of cell types, tissues and organs. Despite significant recent progress in the understanding of calcium (Ca2+) signalling in organs such as the developing and adult brain, we have relatively little knowledge of the contribution of Ca2+ to the development of tubes, structures widely present in multicellular organisms. Here we image Ca2+ dynamics in the developing notochord of Ciona intestinalis. We show that notochord cells exhibit distinct Ca2+ dynamics during specific morphogenetic events such as cell intercalation, cell elongation and tubulogenesis. We used an optogenetically controlled Ca2+ actuator to show that sequestration of Ca2+ results in defective notochord cell intercalation, and pharmacological inhibition to reveal that stretch-activated ion channels (SACs), inositol triphosphate receptor (IP3R) signalling, Store Operated Calcium Entry (SOCE), Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) and gap junctions are required for regulating notochord Ca2+ activity during tubulogenesis. Cytoskeletal rearrangements drive the cell shape changes that accompany tubulogenesis. In line with this, we show that Ca2+ signalling modulates reorganization of the cytoskeletal network across the morphogenetic events leading up to and during tubulogenesis of the notochord. We additionally demonstrate that perturbation of the actin cytoskeleton drastically remodels Ca2+ dynamics, suggesting a feedback mechanism between actin dynamics and Ca2+ signalling during notochord development. This work provides a framework to quantitatively define how Ca2+ signalling regulates tubulogenesis using the notochord as model organ, a defining structure of all chordates.

Independently paced Ca2+ oscillations in progenitor and differentiated cells in an ex vivo epithelial organ

“…The functions of Ca 2+ signaling in mature enteroendocrine cells and enterocytes remain to be elucidated, but several studies in developing tissues and in cultured cells raise attractive possibilities. For example, in developing epithelial tissues, Ca 2+ waves and spikes have been implicated in organizing actomyosin networks ( Balaji et al, 2017 ; Hoyer et al, 2020 preprint; Ready and Chang, 2021 ), remodeling and repair of damaged occluding junctions ( Varadarajan et al, 2022 ), responding to exogenous mechanical loads ( Narciso et al, 2017 ) and coordinating growth at the tissue scale ( Brodskiy et al, 2019 ). It is conceivable that Ca 2+ waves in midgut enterocytes have similar roles, as enterocytes must maintain cytoskeletal networks and occluding-junction-based barrier function during continual mechanical compression due to peristalsis.…”