ER-resident STIM1/2 couples Ca ²⁺ entry by NMDA receptors to pannexin-1 activation

Abstract

Pannexin-1 (Panx1) is a large-pore ion and solute permeable channel highly expressed in the nervous system, where it subserves diverse processes, including neurite outgrowth, dendritic spine formation, and N-methyl D-aspartate (NMDA) receptor (NMDAR)-dependent plasticity. Moreover, Panx1 dysregulation contributes to neurological disorders, including neuropathic pain, epilepsy, and excitotoxicity. Despite progress in understanding physiological and pathological functions of Panx1, the mechanisms that regulate its activity, including its ion and solute permeability, remain poorly understood. In this study, we identify endoplasmic reticulum (ER)-resident stromal interaction molecules (STIM1/2), which are Ca 2+ sensors that communicate events within the ER to plasma membrane channels, as binding and signaling partners of Panx1. We demonstrate that Panx1 is activated to its large-pore configuration in response to stimuli that recruit STIM1/2 and map the interaction interface to a hydrophobic region within the N terminus of Panx1. We further characterize a Panx1 N terminus–recognizing antibody as a function-blocking tool able to prevent large-pore Panx1 activation by STIM1/2. Using either the function-blocking antibody or re-expression of Panx1 deletion mutants in Panx1 knockout (KO) neurons, we show that STIM recruitment couples Ca 2+ entry via NMDARs to Panx1 activation, thereby identifying a model of NMDAR-STIM-Panx1 signaling in neurons. Our study highlights a previously unrecognized and important role of the Panx1 N terminus in regulating channel activation and membrane localization. Considering past work demonstrating an intimate functional relation between NMDARs and Panx1, our study opens avenues for understanding activation modality and context-specific functions of Panx1, including functions linked to diverse STIM-regulated cellular responses.

Diacylglycerol kinase-ε isS-palmitoylated on cysteine in the cytoplasmic end of its N-terminal transmembrane fragment

“…S6D1 and Video1) revealed that as much as 80-90% of the STIM1-decorated ROI overlapped with the DGKε-Myc- decorated ROI (Table 1, M1) and 50-60% of DGKε-Myc-positive ROI colocalized with STIM1-positive ROI (Table 1, M2). STIM1 was concentrated in the perinuclear region resembling the pattern observed earlier in resting HEK293 cells (52). DGKε-Myc and STIM1 colocalized to a high extent in this perinuclear part of the endoplasmic reticulum while they tended to be separated toward the cell periphery (Fig.…”

Human Pannexin 1 Channel is NOT Phosphorylated by Src Tyrosine Kinase at Tyr199 and Tyr309

“…It's possible that additional proteins are involved to relay the signaling output to PANX1. For example, the endoplasmic reticulum (ER)-resident stromal interaction molecules (STIM1/2) have recently been noted to mediate events between NMDAR and PANX1 (40). Future studies are required to fully decipher the underlying mechanisms.…”

Panx1 deletion promotes synaptic reconfiguration and recruitment of cell death pathways in the Zebrafish MPTP model

“…Panx1 channels are expressed in neurons and glial cells, including microglia cells and astrocytes, as well as in the neurovascular unit [17][18][19][20] . Panx1 channels play critical roles in cell death [21][22][23][24][25] , calcium signaling 26,27 , neurotoxicity regulation 28,29 , non-synaptic communication 30,31 , inflammation 22,32,33 , neuronal excitability 34 and endema 35 . The relevance of Panx1's interaction with the cytoskeleton and whether this interaction contributes to cytoskeletal abnormalities in NDDs remains to be explored 36,37 .…”