V‐ATPase‐dependent ectodermal voltage and ph regionalization are required for craniofacial morphogenesis

Abstract

Using voltage and pH reporter dyes, we have discovered a never-before-seen regionalization of the Xenopus ectoderm, with cell subpopulations delimited by different membrane voltage and pH. We distinguished three courses of bioelectrical activity. Course I is a wave of hyperpolarization that travels across the gastrula. Course II comprises the appearance of patterns that match shape changes and gene expression domains of the developing face; hyperpolarization marks folding epithelium and both hyperpolarized and depolarized regions overlap domains of head patterning genes. In Course III, localized regions of hyperpolarization form at various positions, expand, and disappear. Inhibiting H 1 -transport by the H 1 -V-ATPase causes abnormalities in: (1) the morphology of craniofacial structures; (2) Course II voltage patterns; and (3) patterns of sox9, pax8, slug, mitf, xfz3, otx2, and pax6. We conclude that this bioelectric signal has a role in development of the face. Thus, it exemplifies an important, under-studied mechanism of developmental regulation.

Local and long-range endogenous resting potential gradients antagonistically regulate apoptosis and proliferation in the embryonic CNS

“…Brain development disrupted by local V mem perturbation is reversed by long-distance V mem signaling A dynamic endogenous bioelectrical prepattern drives craniofacial development in Xenopus (Vandenberg et al, 2011). The central neural plate cells exhibit a strong hyperpolarization as the neural plate folds to form the neural tube (Pai et al, 2015, Pai et al, 2012a, and forced deviation from this endogenous V mem pattern causes disruption of endogenous brain development (Pai et al, 2015, Pai et al, 2012a.…”

“…Given the role of local V mem states (bioelectric signals in the developing brain region) in shaping brain development (Pai et al, 2015, Pai et al, 2012a, and the importance for coordinating brain size with other anatomical features in vivo, we asked whether non-local V mem distributions (bioelectric states of cells far away from the developing brain) might affect endogenous brain development across long distances. Experimental alteration of V mem was induced by misexpression of well-characterized ion channel mRNAs, a strategy often used to identify functional roles of V mem during embryonic development and regeneration (Adams and Levin, 2006, Aw et al, 2008, Levin et al, 2002, Pai et al, 2012a, Pai and Levin, 2014, Pai et al, 2012b, Perathoner et al, 2014, Vandenberg et al, 2011. We specifically altered V mem of cells within relevant (local and/or nonlocal) regions by injecting mRNAs encoding the hyperpolarizing channel Kv1.5 [voltage-gated potassium channel (Strutz-Seebohm et al, 2007)].…”

“…Dynamic changes in resting membrane potentials (V mem ) carry patterning information during embryonic organ development in Xenopus (Adams and Levin, 2013, Levin, 2014a, Mustard and Levin, 2014, Tseng and Levin, 2013b, Vandenberg et al, 2011. In addition to activity-dependent sculpting of neural connections (Kozorovitskiy et al, 2012, Penn andShatz, 1999), the spatial distribution patterns of V mem in developing embryos controls aspects of large-scale morphogenesis of the nervous system, particularly eye and brain (Beane et al, 2013, Pai et al, 2015, Pai et al, 2012a, Pai et al, 2012b.…”

Bioelectric signaling regulates head and organ size during planarian regeneration

“…proliferation and apoptosis) into animal-wide organization such as allometric tissue scaling (Levin, 2012). Previous work has proposed voltage gradients as mechanisms for sensing and regulating size (Moment, 1949), establishing positional information (Shi and Borgens, 1995), and pre-patterning naïve cell fields (Burr and Northrop, 1935;Vandenberg et al, 2011). This is the first molecular identification of a specific ion translocator necessary for shape control during regeneration and the mechanism by which it sculpts the necessary geometrical changes underlying dynamic remodeling.…”

Xenopus: An ideal system for chemical genetics

“…All of these approaches allow validation of drug-protein interactions, which can be an extremely challenging part of drug discovery. Finally, Xenopus as an in vivo system can provide great insights into the pharmacology of identified compounds as well as anticipating off-target effects (Vandenberg et al, 2011).…”