Structural basis for gating mechanism of Pannexin 1 channel

Mou, Luqiu; Ke, Meng; Song, Mengxiao; Shan, Yuanyue; Xiao, Qicai; Liu, Qingting; Li, Jialu; Sun, Ke; Liao, Pu; Guo, Li; Geng, Jia; Wu, Jianping; Deng, Dong

doi:10.1038/s41422-020-0313-x

Cited by 51 publications

(61 citation statements)

References 16 publications

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“…Over the last ~15 years, Panx1 has been considered as a hexameric channel by analogy to Cx hemichannels (Baranova et al, 2004;Boassa et al, 2007;Bruzzone et al, 2003;Locovei et al, 2006a;Penuela et al, 2007), and based on previous empirical results from EM, chemical crosslinking, and single-molecule photobleaching (Ambrosi et al, 2010;Boassa et al, 2007;Chiu et al, 2017). In contrast, six publications in 2020 presented 16 independent, high-resolution cryoEM 3D reconstructions of various Panx1 constructs (Deng et al, 2020;Jin et al, 2020;Michalski et al, 2020;Mou et al, 2020;Qu et al, 2020;Ruan et al, 2020), which demonstrated that Panx1 assembles as a heptamer. In such studies the highest resolution is achieved by excluding the vast majority of the recorded particle images.…”

Section: Discussionmentioning

confidence: 99%

“…Similar to the impressive productivity in the structural biology of LRRC8A (SWELL1) channels, six publications appeared in 2020 describing 16 independent high-resolution, 3D cryoEM reconstructions of various constructs of frog and human Panx1 channels: PDB codes 6UZY, 6V6D (Deng et al, 2020), PDB codes 6M66, 6M67, 6M68 (Jin et al, 2020), PDB code 6VD7 (Michalski et al, 2020), PDB codes 6LTN, 6LTO (Mou et al, 2020), PDB code 6MO2 (Qu et al, 2020), PDB codes 6WBF, 6WBG, 6WBI, 6WBK, 6WBL, 6WBM, 6WBN (Ruan et al, 2020). All structures demonstrate that Panx1 assembles as a heptamer.…”

Section: Introductionmentioning

confidence: 95%

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A Constitutively Closed Pannexin1 Channel in Lipid Bilayer Nanodiscs Assembles as a Large-Pore Heptamer

Jin

Leonhardt

Chiu

et al. 2021

Preprint

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SUMMARYPannexin 1 (Panx1) channels are widely expressed and play important roles in apoptotic cell clearance, inflammation, blood pressure regulation, neurological disorders, opiate withdrawal, and cancer progression and metastasis. We performed (1) physicochemical analysis on a constitutively closed Panx1 channel (designated fPanx1ΔC) to examine the entire population of particles to detect multiple oligomeric states and (2) cryoEM in the membrane mimetics amphipol A8-35 and lipid bilayer nanodiscs. Our results reveal that the dominant if not exclusive oligomeric state of fPanx1ΔC is a heptamer, in solution and by cryoEM. The Panx1 heptamer provides further structural diversity within the family of large-pore channels, including hexameric LRRC8 (SWELL1) channels and connexin hemichannels, octameric CALHM1 channels and innexin hemichannels, and undecameric CALHM2 channels. Conserved structural themes are a large cytoplasmic vestibule with a diameter that corresponds roughly with the oligomeric state and a 4-helix bundle protomer, albeit with noncanonical helical packing for CALHM1 and CALHM2.In BriefThe 4-helix bundle protomer of a constitutively closed pannexin1 channel assembles as a heptamer in solution and by cryoEM.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

A Constitutively Closed Pannexin1 Channel in Lipid Bilayer Nanodiscs Assembles as a Large-Pore Heptamer

Jin

Leonhardt

Chiu

et al. 2021

Preprint

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“…Notably, PANX1 W74A, which disrupts the ATPdependent interaction with P2X7R and downstream internalization [14,60], also eliminated the increase in cell area triggered by extracellular ATP. Recently published structures of PANX1 at atomic resolution demonstrated that W74 and its neighbouring residue R75 form the anionic selectivity filter for PANX1 [38][39][40]42], likely through the formation of a cation-p interaction that stabilizes both large and small anionic molecules as they move through the narrowest portion of the pore [42]. Alanine substitution of this residue leads to structural change in the extracellular domain and loss of the cation-p interaction and loss of anion-specific selectivity [38,42], allowing for cation permeation [38,42], and loss of carbenoxolone sensitivity [38].…”

Section: Discussionmentioning

confidence: 99%

“…PANX1 forms ubiquitously-expressed heptameric channels that are permeable to small (Cl -) and large (e.g. ATP) anions [38][39][40][41][42][43][44]. Additionally, PANX1 may also regulate the flux of small cations (Ca 2+ ) [45] and release of large cations (spermidine) [46].…”

Section: Introductionmentioning

confidence: 99%

ATP triggers macropinocytosis that internalizes and is regulated by PANX1

Boyce

Slagt

Sanchez-Arias

et al. 2020

Preprint

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Macropinocytosis is an endocytic process that allows cells to respond to changes in their environment by internalizing nutrients and cell surface proteins, as well as modulating cell size. Here, we identify that adenosine triphosphate (ATP) triggers macropinocytosis in murine neuroblastoma cells, thereby internalizing the ATP release channel pannexin 1 (PANX1) while concurrently increasing cross-sectional cellular area. Amiloride, a potent inhibitor of macropinocytosis-associated GTPases, abolished ATP-induced PANX1 internalization and cell area expansion. Transient expression of the GTP-hydrolysis resistant GTPase ARF6 Q67L led to increased PANX1 internalization and increased cell area equivalent to levels seen with ATP stimulation. Mutation of an extracellular tryptophan (W74) in PANX1 abolished ATP-evoked cell area enlargement suggesting that PANX1 regulates this form of macropinocytosis. This novel role of PANX1 in macropinocytosis could be particularly important for disease states implicating PANX1, such as cancer, where ATP can act as a purinergic regulator of cell growth/metastasis and as a supplementary energy source following internalization.

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“…Other TRP subtypes related to high conductance channel formation are the transient potential ankhirin type-1 (TRPA1) cationic channels with a conductance of 87-100 pS and transient potential melastin receptor 8 (TRPM8) with a conductance of 40-83 pS, according to [14,15]. Pannexin-1 [16,17], connexin hemichannel [18], calcium homeostasis modulator 1 (CALHM1) [19], voltage-dependent anion channel (VDAC1 highlighted) [6,20], maxi anion [21], P2X (P2X2 and P2X4) [11], and maitotoxin-induced pore [22] are some other different types of channels with unitary conductance values greater than 200 pS and permeable to molecules of until 1000 Da [4,10,23]. More details about these pore-forming proteins and some techniques used to record their functionality are shown in Table 1.…”

Section: Pore-forming Ionic Channels In Mammalsmentioning

confidence: 99%

Pore-Forming Proteins: Fluorescent Dyes to Study the Channel Functionality and Biophysical Properties

Teixeira¹,

Faria²

2020

Fluorescence Methods for Investigation of Living Cells and Microorganisms

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Large conductance channels, when activated transiently, alter the plasma membrane permeability permitting the passage of molecules with the size of until 1000 Da. These pore-forming proteins are found in the plasma membrane of mammals and invertebrate cells such as the P2X7 receptor, transient receptor potential vanilloid 1 (TRPV1), transient potential melastin receptor 8 (TRPM8), pannexin-1, and hemichannel proteins. Other proteins may be secreted for organisms creating nonselective pathways to large molecules and proteins. Some examples are α-hemolysin and gramicidin. In both cases, an efficient manner to evaluate the functionality is using fluorescent dyes. Thus, we discuss the uses of the fluorescent dyes as tools to study the functionality and some biophysical properties of the proteins described above, among others.

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Structural basis for gating mechanism of Pannexin 1 channel

Cited by 51 publications

References 16 publications

A Constitutively Closed Pannexin1 Channel in Lipid Bilayer Nanodiscs Assembles as a Large-Pore Heptamer

A Constitutively Closed Pannexin1 Channel in Lipid Bilayer Nanodiscs Assembles as a Large-Pore Heptamer

ATP triggers macropinocytosis that internalizes and is regulated by PANX1

Pore-Forming Proteins: Fluorescent Dyes to Study the Channel Functionality and Biophysical Properties

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