Activation of Pannexin 1 (PANX1) ion channels causes release of intercellular signaling molecules in a variety of (patho)physiological contexts. PANX1 can be activated by G protein-coupled receptors (GPCRs), including α1-adrenergic receptors (α1-ARs), but how receptor engagement leads to channel opening remains unclear. Here, we show that GPCR-mediated PANX1 activation can occur via channel deacetylation. We find that α1-AR-mediated activation of PANX1 channels requires Gαq but is independent of phospholipase C or intracellular calcium. Instead, α1-AR-mediated PANX1 activation involves RhoA, mammalian diaphanous (mDia)-related formin, and a cytosolic lysine deacetylase activated by mDia – histone deacetylase 6. HDAC6 associates with PANX1 and activates PANX1 channels, even in excised membrane patches, suggesting direct deacetylation of PANX1.
Fig: Panx1 channel activation by α1D-ARs requires a diffusible messenger: a Exemplar cell-attached patch recording shows phenylephrine (PE, 20 μM)-induced activation of carbenoxolone (CBX, 50 μM)-sensitive channels in HEK293T cells expressing α1D-adrenergic receptors (α1D-ARs) and mPanx1. The schematic illustrates that, in this configuration, the liganded α1D receptor is physically separated from the recorded channel in the patch pipette, activation of which must involve a diffusible messenger. b Effects of PE and CBX on channel activity (maximum PO) in those cell-attached patches (n = 4 membrane patches examined over 4 independent experiments). Data from the exemplar patch recording (in a) is represented by cyan dots. One-way ANOVA (F2,9 = 11.35, p = 0.0035) with Bonferroni’s multiple comparisons test (p values from comparisons are shown).
Substitution of basally-acetylated intracellular lysine residues identified on PANX1 by mass spectrometry either prevents HDAC6-mediated activation (K140/409Q) or renders the channels constitutively active (K140R). These data define a non-canonical RhoA-mDia-HDAC6 signaling pathway for GαqPCR activation of PANX1 channels and uncover lysine acetylation-deacetylation as an ion channel silencing-activation mechanism.
Chiu, YH., Medina, C.B., Doyle, C.A. et al. Deacetylation as a receptor-regulated direct activation switch for pannexin channels. Nat Commun 12, 4482 (2021). https://doi.org/10.1038/s41467-021-24825-y