Pain is a massive problem, particularly amongst the elderly. The revolution in molecular genetics in the late twentieth century coupled with recent advances in protein structure determination has provided powerful insights into how pain works, as well as identifying analgesic drug targets. Peripheral sodium channels are plausible candidates. Today I will discuss recent successes with drugs targeting a voltage-gated sodium channel (NaV1.8), found only in the peripheral nervous system. NaV1.8 mutations have been linked to both pain and cardiovascular problems - even sudden death. The discovery of a role for a small C-terminal fragment of NaV1.8 in cardiac function enables drugs that avoid actions on the heart to be developed. A new orally active drug named Journavx or Suzetrigine is now in the clinic and promises to improve present pain treatment.
In terms of human validation, the sodium channel NaV1.7 is a more compelling target. Humans lacking NaV1.7 are apparently normal but pain-free. However, embyonic pain-free humans and mice lacking NaV1.7 show a distinct mechanism of analgesia from adult knock-out animals. Intriguingly, embryonic NaV1.7 gene deletion enhances endogenous opioid signalling in peripheral neurons, resulting in diminished neurotransmitter release. In contrast, adult gene deletion or channel blocking drugs diminish excitability. NaV1.7 is expressed broadly within the central nervous system, as well as in the autonomic nervous system and some non- neuronal tissues such as the pancreas. Small molecule drug side effects are always a problem, and the broad role of NaV1.7 particularly in the autonomic nervous system means that antagonists of NaV1.7 are toxic . In contrast, the interaction with the opioid system in embryonic nulls presents a fascinating potential new route to pain treatment.
As well as targeting ion channels, the cell populations expressing particular ion channels can be useful analgesic targets. Chemogenetic silencing of neurons expressing NaV1.8 is a highly effective route to causing analgesia in preclinical studies. In addition, neuro-immune interactions can be interrogated through studies of neuron-depleted mice.
The voltage-gated sodium channel NaV1.5, encoded by the SCN5A gene, is central to cardiac cellular excitability; the generation and propagation of the action potential, to effect muscle contraction. It is commonly referred to as the cardiac sodium channel with the view that its expression and function is restricted to this organ. However, a mounting body of evidence indicates its presence in extra-cardiac non-excitable cells and tissues, where it contributes to pathological states including cancer. Interestingly, it appears that these extra cardiac populations may largely be alternatively spliced variants of SCN5A, including the neonatal and macrophage variants. The selective recognition of specific NaV1.5 variants is important for determining their expression patterns and mechanistic roles, as well as for diagnostic and therapeutic purposes. One approach is to generate antibodies which recognise unique epitopes. We have utilised a phage display human single chain fragment antibody (scFv) library to selectively target NaV1.5 in the heart and cancer. Suitable extracellular sequences of NaV1.5 which could form appropriate epitopes were identified via a bioinformatic search. These peptide sequences were used to screen the scFv library and selected scFv clones then evaluated for binding against the full-length channel protein, and for potential functional consequences. Here I will present our recent and ongoing work concerning one of the scFvs recognising a common epitope within the S3-S4 extracellular loop of DIII that demonstrates robust binding with functional consequences, and the work to validate the neonatal specific scFvs.
Multi-pass transmembrane proteins such as GPCRs, ion channels, and transporters are central regulators of cellular signalling, communication, and homeostasis. These membrane proteins account for approximately 20–30% of all proteins encoded by sequenced genomes and constitute key therapeutic targets. Despite their significance, recombinant production of stable, functional membrane proteins remains a major bottleneck. Their reliance on a native lipid bilayer environment complicates expression, purification, and structural analysis.
Amphipathic copolymers have enabled detergent-free extraction of membrane proteins into nanodisc assemblies that retain endogenous lipids, offering a more native environment than traditional detergents. Nevertheless, many membrane proteins remain recalcitrant to current polymer-nanodisc methodologies, exhibiting poor solubility, aggregation, or instability that restricts their use in biochemical and structural studies.
Here, we describe a novel, compact fusion tag that substantially improves the behaviour of diverse multi-pass membrane proteins within polymer nanodiscs. Across multiple targets, the tag enhances recombinant yield and confers improved solubility and stability while reducing aggregation. These improvements facilitate higher concentrations suited to downstream biophysical and structural workflows. Applying this approach, we report the first detergent‑free cryo‑electron microscopy structure of the ion channel TrpML3, establishing a route to stabilizing challenging membrane proteins without detergents.
To follow
The evolution of automated patch-clamp platforms has transformed electrophysiology and its role in drug discovery. Although manual patch-clamp remains the gold standard for precise ion channel measurements, its low throughput and technical complexity has limited its use in large-scale applications.
Technological advances in microfluidics, planar electrode systems, and robotics have enabled the development of automated platforms capable of parallel, high-throughput recordings. In the last two decades, these systems have improved in data quality, reliability, and throughput bringing their performance closer to that of manual approaches while significantly increasing efficiency.
In drug discovery, automated patch-clamp technologies are now widely used to screen and characterise ion channel modulators. They enable rapid evaluation of compound potency, selectivity, and safety risks, including cardiotoxicity. Their scalability supports both early-stage screening and later phases of lead optimization, helping to accelerate decision-making.
Sensory dysfunction, including chronic pain and itch, is often associated with peripheral sensitization of sensory neurons, with communication between nerve and local tissue environment emerging as an important contributor in regulating the response in many pathologies. Pro-inflammatory mediators released by local stromal and immune cells can modulate ion channels and thus sensory neuronal excitability, and we sought to investigate this using techniques including multi-electrode array and neuropeptide release assays. The hematopoietic growth factor and cytokine GM-CSF was of particular interest due to robust analgesia observed in early anti-GM-CSF clinical studies in osteoarthritis. In order to understand the mechanism by which GM-CSF could alter neuronal signalling in pain pathways associated with chronic neuropathic pain, we deployed a variety of electrophysiological, immunological, transcriptomic and behavioural techniques in wild-type and transgenic animals targeting the GM-CSF pathway. We show GM-CSF does not directly alter sensory neuronal excitability, but we identify a novel and fundamental process whereby peripheral nerve injury induces GM-CSF release from group 2 innate lymphoid cells (ILC2s) and instructs vertebral bone marrow emergency myelopoiesis. As such, we link meningeal immunity to vertebral bone marrow emergency myelopoiesis in neuropathic pain and reveal the mechanism by which GM-CSF acts to orchestrate this neuroimmune axis.
Note all experimental procedures were carried out in accordance with UK Home Office Animals (Scientific Procedures) Act 1986 and the GSK Policy on the Care, Welfare and Treatment of Laboratory Animals.
Ion channels are critical drivers of visceral nociception in gastrointestinal diseases such as irritable bowel syndrome and inflammatory bowel disease causing pain and significantly impacting quality of life for people during both active disease and remission.
Here we describe the investigation and human tissue validation of ion channels such as NaV1.9 and TRPV4, involved in the transduction of noxious stimuli and their regulation by G protein-coupled receptors such as GPR35. These studies highlighting the future therapeutic targets for the treatment of pain in gastrointestinal disease.