Biology subjects

Blunck, R.

Publications and source records attributed to Blunck, R..

5 recordsLinked to original sources

bioRxiv2024

From resting state to inactivation: the dynamic journey of the inactivation peptide in Shaker Kv channels

Shaker Kv channels inactivate rapidly to culminate the action potential and maintain the homeostasis of excitable cells. The so-called N-type inactivation is caused by the first 46 amino acids of the N-terminus of the channel, known as the inactivation peptide. Numerous mutational studies have characterized N-type inactivation functionally, however, the position of the inactivation peptide in the resting state and its transition during inactivation is still debated. Here, we tracked the movement of the inactivation peptide during inactivation using voltage clamp fluorometry. By inserting an unnatural amino acid, 3-[(6-acetyl-2-naphthalenyl) amino]-L-alanine (Anap), which is sensitive to changes in environment, we identified the movements of ball and chain separately. Our data suggests that N-type inactivation occurs in a biphasic movement by first releasing the IP, which then blocks the pore from the cytoplasmic side. To further narrow down the resting position of the inactivation peptide, we used Lanthanide-based Resonance Energy transfer and transition metal (tm)FRET. We propose that the inactivation peptide is located in the window formed by the channel and the T1 domain, interacting with the acidic residues of the T1 domain.

biophysics↗

bioRxiv2024

KCNG4 genetic variant linked to migraine prevents expression of KCNB1

AO_SCPLOWBSTRACTC_SCPLOWMigraines are a common type of headaches affecting around 15% of the population. The signalling pathways leading to migraines have not been fully understood, but neuronal voltage-gated ion channels have been linked to this pathology, among them KCNG4. KCNG4 (Kv6.4) is a silent member of the superfamily of voltage-gated potassium (Kv) channels, which expresses in heterotetramers with members of the KCNB (Kv2) family. The genetic variant Kv6.4-L360P has previously been linked to migraine, but their mode of action remains unknown. Here, we characterized the molecular characteristics of Kv6.4-L360P when co-expressed with Kv2.1. We found that Kv6.4-L360P almost completely abolishes Kv2 currents, and we propose that this mechanism in the trigeminal system, linked to the initiation of migraine, leads to the pathology.

biophysics↗

bioRxiv2023

IL-13 promotes sensory-sympathetic neurons crosstalk in asthma

Nociceptor neurons play a crucial role in maintaining the bodys homeostasis by detecting and responding to potential dangers in the environment. However, this function can be detrimental during allergic reactions, since vagal nociceptors can contribute to immune cell infiltration, bronchial hypersensitivity, and mucus imbalance, in addition to causing pain and coughing. Despite this, the specific mechanisms by which nociceptors acquire pro-inflammatory characteristics during allergic reactions are not yet fully understood. In this study, we aimed to investigate the molecular profile of airway nociceptor neurons during allergic airway inflammation and identify the signals driving such reprogramming. Using retrograde tracing and lineage reporting, we identified a unique class of inflammatory vagal nociceptor neurons that exclusively innervate the airways. In the ovalbumin mouse model of airway inflammation, these neurons undergo significant reprogramming characterized by the upregulation of the NPY receptor Npy1r. A screening of cytokines and neurotrophins revealed that IL-1{beta}, IL-13 and BDNF drive part of this reprogramming. IL-13 triggered Npy1r overexpression in nociceptors via the JAK/STAT6 pathway. In parallel, sympathetic neurons and macrophages release NPY in the bronchoalveolar fluid of asthmatic mice, which limits the excitability of nociceptor neurons. Single-cell RNA sequencing of lung immune cells has revealed that a cell-specific knockout of Npy1r in nociceptor neurons in asthmatic mice leads to an increase in airway inflammation mediated by T cells. Opposite findings were observed in asthmatic mice in which nociceptor neurons were chemically ablated. In summary, allergic airway inflammation reprograms airway nociceptor neurons to acquire a pro-inflammatory phenotype, while a compensatory mechanism involving NPY1R limits nociceptor neurons activity.

neuroscience↗

bioRxiv2020

Role of transmembrane helix 6 in substrate recognition of the amino acid transporter MhsT

MhsT of Bacillus halodurans is a transporter of hydrophobic amino acids and a homologue of the eukaryotic SLC6 family of Na+-dependent symporters for amino acids, neurotransmitters, osmolytes, or creatine. The broad range of transported amino acids by MhsT prompted the investigation of the substrate recognition mechanism. Here, we report six new substrate-bound structures of MhsT, which, in conjunction with functional studies, reveal how the flexibility of a Gly-Met-Gly (GMG) motif in the unwound region of transmembrane segment 6 (TM6) is central for the recognition of substrates of different size by tailoring the binding site shape and volume. MhsT mutants, harboring substitutions within the unwound GMG loop and substrate binding pocket that mimick the binding sites of eukaryotic SLC6A18/B0AT3 and SLC6A19/B0AT1 transporters of neutral amino acids, exhibited impaired transport of aromatic amino acids that require a large binding site volume. Conservation of a general (G/A/C){Phi}G motif among eukaryotic members of SLC6 family suggests a role for this loop in a common mechanism for substrate recognition and translocation by SLC6 transporters of broad substrate specificity.

biochemistry↗

bioRxiv2018

TACAN is an essential component of the mechanosensitive ion channel responsible for pain sensing

Mechanotransduction, the conversion of mechanical stimuli into electrical signals, is a fundamental process underlying several physiological functions such as touch and pain sensing, hearing and proprioception. This process is carried out by specialized mechanosensitive ion channels whose identities have been discovered for most functions except pain sensing. Here we report the identification of TACAN (Tmem120A), an essential subunit of the mechanosensitive ion channel responsible for sensing mechanical pain. TACAN is expressed in a subset of nociceptors, and its heterologous expression increases mechanically-evoked currents in cell lines. Purification and reconstitution of TACAN in synthetic lipids generates a functional ion channel. Finally, knocking down TACAN decreases the mechanosensitivity of nociceptors and reduces behavioral responses to mechanical but not to thermal pain stimuli, without affecting the sensitivity to touch stimuli. We propose that TACAN is a pore-forming subunit of the mechanosensitive ion channel responsible for sensing mechanical pain.

neuroscience↗