Biology subjects

Feliciangeli, S.

Publications and source records attributed to Feliciangeli, S..

5 recordsLinked to original sources

bioRxiv2026

Gain- and loss-of-function mutations cause perinatal lethality in mouse models of Birk-Barel syndrome

Birk-Barel syndrome (BBS), also known as KCNK9 imprinting syndrome, is a neurodevelopmental disorder caused by mutations in the maternally expressed paternally imprinted KCNK9 gene that encodes the TASK3 potassium channel. The first mutation identified in patients with BBS was a loss-of-function variant that reduces the potassium current mediated by TASK3. Subsequent studies have uncovered additional pathogenic variants, including gain-of-function mutations, that increase TASK3 activity. Here, we show that both mutations resulted in the expression of the hyperactive Task3M159I variant or the hypoactive Task3G236R variant, which caused early postnatal lethality in mice when maternally inherited, confirming the monogenic nature of BBS. These results indicate that the pathogenesis of BBS involves mechanisms other than alterations in channel activity. Consequently, the proposed therapeutic strategies, such as pharmacological modulation of the TASK3 channel function or epigenetic reactivation of the paternal KCNK9 allele, do not seem to be viable options. These findings also demonstrate that TASK3 knockout mice are not suitable models for studying KCNK9 imprinting syndrome or for developing therapies for affected patients. Therefore, there is an urgent need for animal models that allow conditional expression of BBS-associated mutations.

pharmacology and toxicology↗

bioRxiv2025

Two pore domain THIK2 channel is involved in acute and chronic pain signal regulation

Two-pore domain potassium channels (K2P) regulate neuronal excitability by acting as hyperpolarizing leak channels. Among them, THIK2 remain poorly characterized. Although no study has yet clearly linked them to excitability or pain, their selective expression in nociceptive neurons of the Dorsal Root Ganglia (DRG) suggests a role in nociception and pain regulation. This project investigates THIK2 channels in pain pathophysiology through molecular, electrophysiological, and behavioral approaches. We mapped THIK expression patterns and in THIK2 knock-out mice, we examined DRG neuron excitability and pain sensitivity. Results reveal thermal hypersensitivity under both naive and inflammatory conditions, indicating that THIK2 normally limits neuronal hyperexcitability. These findings position THIK2 as a potential therapeutic target in chronic inflammatory pain, with peripheral inhibition potentially offering analgesia without central opioid side effects.

neuroscience↗

bioRxiv2023

Mechanistic basis of the dynamic response of TWIK1 ionic selectivity to pH

At neutral pH, the TWIK1 channel is highly selective for K+. When exposed to acidification, it becomes permeable to Na+. This change occurs within minutes and is reversible. By combining pKa calculations, molecular dynamics (MD) simulations, mutagenesis and electrophysiology, we identified a network of residues involved in this unique property. MD simulations captured crucial features associated with channel gating and previously observed by cryogenic electron microscopy (cryo-EM) at pH7.4 and pH5, such as the pH-dependent orientation of the lateral side chain of the proton sensor His122 and the elongation of the entire pore structure upon acidification. Between the closed and open states of TWIK1 observed by cryo-EM, MD simulations show that the channel undergoes additional conformational changes between pH 7.5 to 6 that involves the His122, Glu235, Lys246 and Phe109 residues. A complex network of interactions surrounding the selectivity filter at high pH transforms into a simple set of stronger interactions at low pH. In particular, His122 protonated by acidification moves away from Lys246 and engages in a salt bridge with Glu235. In addition, stacking interactions between Phe109 and His122, which stabilize the selectivity filter in its K+-selective state at high pH, disappear upon acidification. This causes dissociation of the Phe109 aromatic side chain from this network, ultimately leading to the Na+-permeable conformation of the channel.

biochemistry↗

bioRxiv2023

Predicting hERG repolarization power at 37°C from recordings at room temperature

Mutations in the KCNH2 gene cause long or short QT syndromes (LQTS or SQTS) predisposing to life-threatening arrhythmias. KCNH2 encodes for the voltage-gated K+ channel hERG involved in the late repolarization phase of the cardiac action potential (AP). For the last decades, sequencing KCNH2 has provided a plethora of variants associated or not with clear pathological cardiac phenotypes. Identifying pathogenic or likely pathogenic variants from the benign ones would provide useful information to clarify the genetic background of LQTS patients and relatives, and to stratify the risk of adverse events. In face of a wide spectrum of hERG biophysical defects, we looked for a way to summarize the net loss or gain of function in a unique index. In a previous work, we defined as the repolarization power the time integral of the K+ currents developed during an AP clamp. Here, with the aim of accelerating the functional characterization of hERG variants using automated patch-clamp, we adapted the AP-clamp protocol to establish, at room temperature, at which the recording success rate is high, a repolarization power index, as reliable and informative as the one measured at physiological temperature. We also illustrate that the repolarization power determined at room temperature is predictive of the repolarization power at physiological temperature for 2 pathogenic hERG variants with different biophysical dysfunctions.

physiology↗

bioRxiv2021

Heteromerization of alkaline-sensitive two-pore domain potassium channels

Two-pore domain (K2P) potassium channels are active as dimers. They produce inhibitory currents regulated by a variety of stimuli. Among them, TALK1, TALK2 and TASK2 form a subfamily of structurally related K2P channels stimulated by extracellular alkalosis. The human genes encoding them are clustered on chromosomal region 6p21. They are expressed in different tissues including the pancreas. By analyzing single cell transcriptomic data, we show that these channels are co-expressed in insulin-secreting pancreatic {beta} cells. By different approaches we show that they form functional heterodimers. Heteromerization of TALK2 with TALK1 or with TASK2 endorses TALK2 with sensitivity to extracellular alkalosis in the physiological range. The association of TASK2 with TALK1 and TALK2 increases their unitary conductance. These results provide a new example of heteromerization in the K2P channel family expanding the range of their potential physiological and pathophysiological roles.

molecular biology↗