Unified patch clamp protocol for the characterization of Pannexin 1 channels in isolated cells and acute brain slices

Gründken, Christina; Hanske, Julian; Wengel, Stephanie; Reuter, Wiebke; Abdulazim, Amr; Shestopalov, Valery I.; Dermietzel, Rolf; Zoidl, Georg; Prochnow, Nora

doi:10.1016/j.jneumeth.2011.04.016

Cited by 13 publications

(14 citation statements)

References 49 publications

(64 reference statements)

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“…Using ion gradient conditions that mimic physiological conditions, a simple voltage step paradigm like I (Figure 6A) opened only a limited number of channels in trial experiments. Since we were interested to promote robust Panx1 channel opening and closure, a combined depolarizing holding voltage step and long ramp preconditioning paradigm (modified from [33] was applied. Previous studies from our group let us chose three ramps to analyze whether a preconditioning effect was long lasting.…”

Section: Resultsmentioning

confidence: 99%

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Pannexin1 Channel Proteins in the Zebrafish Retina Have Shared and Unique Properties

et al. 2013

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In mammals, a single pannexin1 gene (Panx1) is widely expressed in the CNS including the inner and outer retinae, forming large-pore voltage-gated membrane channels, which are involved in calcium and ATP signaling. Previously, we discovered that zebrafish lack Panx1 expression in the inner retina, with drPanx1a exclusively expressed in horizontal cells of the outer retina. Here, we characterize a second drPanx1 protein, drPanx1b, generated by whole-genome duplications during teleost evolution. Homology searches strongly support the presence of pannexin sequences in cartilaginous fish and provide evidence that pannexins evolved when urochordata and chordata evolution split. Further, we confirm Panx1 ohnologs being solely present in teleosts. A hallmark of differential expression of drPanx1a and drPanx1b in various zebrafish brain areas is the non-overlapping protein localization of drPanx1a in the outer and drPanx1b in the inner fish retina. A functional comparison of the evolutionary distant fish and mouse Panx1s revealed both, preserved and unique properties. Preserved functions are the capability to form channels opening at resting potential, which are sensitive to known gap junction and hemichannel blockers, intracellular calcium, extracellular ATP and pH changes. However, drPanx1b is unique due to its highly complex glycosylation pattern and distinct electrophysiological gating kinetics. The existence of two Panx1 proteins in zebrafish displaying distinct tissue distribution, protein modification and electrophysiological properties, suggests that both proteins fulfill different functions in vivo.

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Section: Resultsmentioning

confidence: 99%

“…Further we used a modified preconditioning paradigm recently shown to evoke increased Panx1-mediated currents [33]. For drPanx1b channels, this technical modification evoked large outwards currents at potentials ≥ +30 mV and channel opening at negative potentials.…”

Section: Discussionmentioning

confidence: 99%

Pannexin1 Channel Proteins in the Zebrafish Retina Have Shared and Unique Properties

et al. 2013

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“…Panx1 +/+ mice (Panx1fl/fl) with three LoxP consensus sequences integrated into the Panx1 gene and knockout mice with global loss of Panx1 (Panx1 −/− , CMV-Cre/Panx1) were described previously (Gründken et al, 2011; Dvoriantchikova et al, 2012; Prochnow et al, 2012). Handling and housing of animals used in this study was performed in compliance with the German Animal Rights law and approved by the Landesamt für Natur, Umwelt und Verbraucherschutz Nordrhein-Westfalen, Germany (Permission No.…”

Section: Methodsmentioning

confidence: 99%

Investigation of olfactory function in a Panx1 knock out mouse model

Kurtenbach

Whyte-Fagundes

Gelis

et al. 2014

Front. Cell. Neurosci.

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Pannexin 1 (Panx1), the most extensively investigated member of a channel-forming protein family, is able to form pores conducting molecules up to 1.5 kDa, like ATP, upon activation. In the olfactory epithelium (OE), ATP modulates olfactory responsiveness and plays a role in proliferation and differentiation of olfactory sensory neurons (OSNs). This process continuously takes place in the OE, as neurons are replaced throughout the whole lifespan. The recent discovery of Panx1 expression in the OE raises the question whether Panx1 mediates ATP release responsible for modulating chemosensory function. In this study, we analyzed pannexin expression in the OE and a possible role of Panx1 in olfactory function using a Panx1−/− mouse line with a global ablation of Panx1. This mouse model has been previously used to investigate Panx1 functions in the retina and adult hippocampus. Here, qPCR, in-situ hybridization, and immunohistochemistry (IHC) demonstrated that Panx1 is expressed in axon bundles deriving from sensory neurons of the OE. The localization, distribution, and expression of major olfactory signal transduction proteins were not significantly altered in Panx1−/− mice. Further, functional analysis of Panx1−/− animals does not reveal any major impairment in odor perception, indicated by electroolfactogram (EOG) measurements and behavioral testing. However, ATP release evoked by potassium gluconate application was reduced in Panx1−/− mice. This result is consistent with previous reports on ATP release in isolated erythrocytes and spinal or lumbar cord preparations from Panx1−/− mice, suggesting that Panx1 is one of several alternative pathways to release ATP in the olfactory system.

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“…Cell type must be carefully chosen when designing future experiments, and investigators should be especially mindful of the conditions used during recordings if attempting to compare between their own results and those reported in other studies. To help the field reach consensus, a standardized patch clamp paradigm for eliciting Panx1 currents has been proposed by Grundken and colleagues, so if practical, investigators may want to consider adopting their method (Grundken et al, 2011). …”

Section: Pannexinsmentioning

confidence: 99%

The pannexins: past and present

Bond

Naus

2014

Front. Physiol.

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The pannexins (Panxs) are a family of chordate proteins homologous to the invertebrate gap junction forming proteins named innexins. Three distinct Panx paralogs (Panx1, Panx2, and Panx3) are shared among the major vertebrate phyla, but they appear to have suppressed (or even lost) their ability to directly couple adjacent cells. Connecting the intracellular and extracellular compartments is now widely accepted as Panx's primary function, facilitating the passive movement of ions and small molecules along electrochemical gradients. The tissue distribution of the Panxs ranges from pervasive to very restricted, depending on the paralog, and are often cell type-specific and/or developmentally regulated within any given tissue. In recent years, Panxs have been implicated in an assortment of physiological and pathophysiological processes, particularly with respect to ATP signaling and inflammation, and they are now considered to be a major player in extracellular purinergic communication. The following is a comprehensive review of the Panx literature, exploring the historical events leading up to their discovery, outlining our current understanding of their biochemistry, and describing the importance of these proteins in health and disease.

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Unified patch clamp protocol for the characterization of Pannexin 1 channels in isolated cells and acute brain slices

Cited by 13 publications

References 49 publications

Pannexin1 Channel Proteins in the Zebrafish Retina Have Shared and Unique Properties

Pannexin1 Channel Proteins in the Zebrafish Retina Have Shared and Unique Properties

Investigation of olfactory function in a Panx1 knock out mouse model

The pannexins: past and present

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