Endogenous Gradients of Resting Potential Instructively Pattern Embryonic Neural Tissue via Notch Signaling and Regulation of Proliferation

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

“…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)]. The effect of introducing this ion channel mRNA on V mem of cranial and other cells in the embryo has previously been characterized at stages 10-21 using the voltage reporter dyes and electrophysiology (Pai et al, 2015, Pai et al, 2012a, confirming its ability to efficiently hyperpolarize expressing cells. In vivo, Kv1.5 misexpression eliminates the endogenous V mem differences and spatial gradients within the group of channel expressing cells, driving expressing cells to ~-58 mV, from an endogenous polarization level of ~-20 mV or ~-50 mV of cells outside and inside the prospective brain respectively.…”

“…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.…”

“…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.…”

“…Such patterns of resting potential within living tissues (bioelectric signals) have been studied in the context of their roles in cell migration and wound healing (Cao et al, 2013, Jaffe, 1979, McCaig et al, 2005, Richard B. Borgens, 1989, Zhao et al, 2006 and have long been proposed to direct growth and form in vivo (Burr, 1932). Bioelectric signals are implicated in vertebrate appendage regeneration , Tseng et al, 2010, cancer initiation and metastasis (Binggeli and Weinstein, 1986b, Blackiston et al, 2011, Brackenbury, 2012, Chernet and Levin, 2013b, Lobikin et al, 2012b, left-right patterning (Aw et al, 2008, Aw et al, 2010, Levin et al, 2002, planarian head induction (Beane et al, 2011, Beane et al, 2013, Marsh and Beams, 1947, and eye and brain formation (Nuckels et al, 2009, Pai et al, 2015, Pai et al, 2012a, Pai et al, 2012b. Thus bioelectric signals have been shown to be important regulators of large-scale patterning and tissue and organ identity (Levin, 2009, Levin, 2013a, Levin and Stevenson, 2012, Tseng and Levin, 2013a.…”

Selective depolarization of transmembrane potential alters muscle patterning and muscle cell localization in Xenopus laevis embryos

“…eGFP-TPC3 construct was received from Chunlei Cang (Cang et al, 2014) and subcloned into PCS2 for the synthesis of messenger RNA. Other constructs used included Tol2-CarPr-GFP3, Tol2-CarPr-GlyR-A288G-GFP3 (in which human GlyR-A288G (Lobikin et al, 2012, Lynagh andLynch, 2010) was inserted into Tol2-CarPr-GFP3), Tol2-NBT2-GlyR-A288G-tomto (made by replacing GFP3 in Tol2-NBT2-GFP3 (Pai, 2015) with GlyR-A288G-tomato). Cardiac actin promoter and neural tubulin promoters were the same as those used for transgenic frogs.…”