Recent advances in the structure and activation mechanisms of metabolite-releasing Pannexin 1 channels

PANX1 hexamers work but cells prefer heptamers

Gupta et al. (https://doi.org/10.1085/jgp.202413676) reconcile a disconnect between structural and functional data regarding stoichiometry of PANX1 channels and provide new insights about channel activation.

Novel Naphthyridones Targeting Pannexin 1 for Colitis Management

Pannexin 1 (PANX1) forms cell-surface channels capable of releasing signaling metabolites for diverse patho-physiological processes. While inhibiting dysregulated PANX1 has been proposed as a therapeutic strategy for many pathological conditions, including inflammatory bowel disease (IBD), low efficacy, or poor specificity of classical PANX1 inhibitors introduces uncertainty for their applications in basic and translational research. Here, hit-to-lead optimization is performed and a naphthyridone, compound 12, is identified as a new PANX1 inhibitor with an IC50 of 0.73 µm that does not affect pannexin-homologous LRRC8/SWELL1 channels. Using structure-activity relationship analysis, mutagenesis, cell thermal shift assays, and molecular docking, it is revealed that compound 12 directly engages PANX1 Trp74 residue. Using a dextran sodium sulfate mouse model of IBD, it is found that compound 12 markedly reduced colitis severity, highlighting new PANX1 inhibitors as a proof-of-concept treatment for IBD. These data describe the mechanism of action for a new PANX1 inhibitor, uncover the binding site for future drug design, and present a targeted strategy for treating IBD.

Ion channels in macrophages: Implications for disease progression

RATIONALE

Macrophages are immune cells found throughout the body and exhibit morphological and functional diversity. Macrophages have been implicated in a wide range of diseases, including autoimmune diseases, acute liver injury, cardiovascular diseases, lung diseases and tumours. Ion channels are transmembrane glycoproteins with important functions in maintaining homeostasis in the intra- and extracellular environment and mediating signal transduction. Many studies have shown that different types of ion channels influence the role of macrophages in the development of various diseases. In recent years, studies on the role of ion channels in macrophages in immune regulation and inflammatory responses have attracted much attention.

OBJECTIVE AND FINDINGS

In order to gain a deeper understanding of the role of macrophage ion channels, this paper reviews the recent research progress on the role of macrophage ion channels in recent years. The aim is to explore the role of different ion channels in the regulation of macrophage function and their impact on a variety of disease processes. The most studied channels are calcium, sodium and potassium channels, most of which are located in the cell membrane. Among these, TRP channels have a more complex role in M1 and M2 macrophage types.

CONCLUSION

Ion channels are critical for the functional regulation of macrophages. Targeting ion channels provides new avenues for disease prevention and treatment. This review provides researchers with new ideas and introduces readers to the current state of research on ion channels in macrophages.

Channel plan: control of adaptive immune responses by pannexins

The development of mammalian adaptive (i.e., B and T cell-mediated) immune responses is tightly controlled at transcriptional, epigenetic, and metabolic levels. Signals derived from the extracellular milieu are crucial regulators of adaptive immunity. Beyond the traditionally studied cytokines and chemokines, many other extracellular metabolites can bind to specialized receptors and regulate T and B cell immune responses. These molecules often accumulate extracellularly through active export by plasma membrane transporters. For example, mammalian immune and non-immune cells express pannexin (PANX)1-3 channels on the plasma membrane, which release many distinct small molecules, notably intracellular ATP. Here, we review novel findings defining PANXs as crucial regulators of T and B cell immune responses in disease contexts such as cancer or viral infections.

Targeting Pannexin-1 Channels: Addressing the 'Gap' in Chronic Pain

Chronic pain complicates many diseases and is notoriously difficult to treat. In search of new therapeutic targets, pannexin-1 (Panx1) channels have sparked intense interest as a key mechanism involved in a variety of chronic pain conditions. Panx1 channels are transmembrane proteins that release ions and small molecules, such as adenosine triphosphate (ATP). They are expressed along important nodes of the pain pathway, modulating activity of diverse cell types implicated in the development and progression of chronic pain caused by injury or pathology. This review highlights advances that have unlocked the core structure and machinery controlling Panx1 function with a focus on understanding and treating chronic pain.