Potassium channel agonists emerging as treatment options for focal epilepsy: are we breaking new ground? Cristiana Pelorosso, Simona Balestrini, Renzo Guerrini Expert Opinion on Emerging Drugs, 2026 INTRODUCTION: Focal epilepsy is a leading cause of neurological disability, with about one-third of patients failing to achieve seizure freedom despite numerous antiseizure medications (ASMs) are available. Most current therapies broadly modulate synaptic transmission, leading to dose-limiting cognitive, psychiatric, and systemic adverse effects. Kv7 (KCNQ) potassium channels, responsible for the neuronal M-current, represent a high-precision therapeutic target that regulates intrinsic excitability and provides a fundamental 'molecular brake' against pathological firing. AREAS COVERED: This mini-review summarizes the clinical evolution of Kv7 modulation, from the first-generation prototype ezogabine to more selective second-generation candidates. We outline the scientific rationale for targeting the M-current, review emerging clinical data for agents such as azetukalner (XEN1101) and opakalim (BHV-7000), and highlight preclinical strategies including dual-mechanism modulators and drug repurposing. EXPERT OPINION: Kv7 agonists offer a mechanistically elegant approach to restoring seizure resistance. Second-generation agents provide encouraging mechanistic and clinical proof-of-concept, but long-term success will depend on clear advantages in patient-centered outcomes over established ASMs. Future value is likely to lie in precision-medicine strategies for KCNQ2/3-related encephalopathies and a carefully defined role in managing neuropsychiatric comorbidities.
Mosaic expression of SLC35A2 pathogenetic variants impairs neuronal migration and dendritogenesis in the developing cortex Antonio Falace, Léa Corbières, Lucas Silvagnoli, Cristiana Pelorosso, Clara Tuccari di San Carlo, Emmanuelle Buhler, Zeinab Hoteit, Sylvian Bauer, Beatrice Risso, Quenol Cesar, Emilie Pallesi-Pocachard, Jean-Bernard Manent, Carmen Barba, Renzo Guerrini, Carlos Cardoso, Valerio Conti Human Molecular Genetics, 2025 Brain somatic variants in the SLC35A2 gene, encoding for a Golgi galactose transporter, represent the major cause of mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). Clinical features associated with MOGHE include early-onset epileptic encephalopathy, drug-resistant focal epilepsy with developmental delay, and intellectual disability. Half of somatic SLC35A2 variants identified in MOGHE patients are predicted to encode full-length SLC35A2 protein or stable protein products. We investigated the pathophysiological basis of MOGHE by analyzing the functional consequences of SLC35A2 pathogenetic variants in vitro and in vivo models. We assessed how different SLC35A2 variants impact protein stability and expression in transfected cellular models. We used in utero electroporation in the rat brain to model mosaic expression of SLC35A2 pathogenetic variants in the cerebral cortex and assessed their effect on neurons migration and morphology. We found that SLC35A2 variants identified in MOGHE patients variably impact on SLC35A2 protein expression. In utero expression of a SLC35A2 missense (p.G282A) or frameshift (p.F280Tfs*10) variants resulted in neuronal heterotopia in the white matter and impaired dendritogenesis at postnatal stages, suggesting a cell autonomous role for SLC35A2 in neuronal development. These phenotypes were recapitulated by in utero silencing of rat Slc35a2 gene. We successfully developed an in vivo mosaic model for the characterization of SLC35A2 variants identified in MOGHE patients and demonstrated that the expression of single SLC35A2 variants triggers the pathophysiological cascade associated with SLC35A2 dysfunction in neurons.
Quantitative cytoarchitectural phenotyping of deparaffinized human brain tissues Danila Di Meo, Michele Sorelli, Josephine Ramazzotti, Franco Cheli, Samuel Bradley, Laura Perego, Beatrice Lorenzon, Giacomo Mazzamuto, Aron Emmi, Andrea Porzionato, Raffaele De Caro, Rita Garbelli, Dalila Biancheri, Cristiana Pelorosso, Valerio Conti, Renzo Guerrini, Francesco S. Pavone, Irene Costantini Communications Biology, 2025 Advanced 3D imaging techniques and image segmentation and classification methods can transform biomedical research by offering insights into the human brain cytoarchitecture under pathological conditions. We propose a comprehensive pipeline for 3D imaging and automated quantitative cellular phenotyping on Formalin-Fixed Paraffin-Embedded human brain specimens. We exploit the versatility of our method by applying it to different human specimens from both adult and pediatric, normal and abnormal brain regions. Quantitative data on neuronal morphology, local density, and spatial clustering level are obtained from a machine-learning-based analysis of the 3D cytoarchitectural organization of cells identified by different molecular markers in two subjects with malformations of cortical development. This approach grants access to a wide range of clinical specimens, allowing for volumetric imaging and quantitative analysis of human brain samples at cellular resolution. Possible genotype-phenotype correlations can be unveiled, providing insights into the pathogenesis of various brain diseases and enlarging treatment opportunities. A deparaffinization, 3D imaging and quantitative cytoarchitectural phenotyping method for human brains reveals structural differences in patients with Malformation of Cortical Development, advancing analysis of brain pathology at cellular resolution.
Stretch-activated ion channel TMEM63B associates with developmental and epileptic encephalopathies and progressive neurodegeneration Annalisa Vetro, Cristiana Pelorosso, Simona Balestrini, Alessio Masi, Sophie Hambleton, Emanuela Argilli, Valerio Conti, Simone Giubbolini, Rebekah Barrick, Gaber Bergant, Karin Writzl, Emilia K. Bijlsma, Theresa Brunet, Pilar Cacheiro, Davide Mei, Anita Devlin, Mariëtte J.V. Hoffer, Keren Machol, Guido Mannaioni, Masamune Sakamoto, Manoj P. Menezes, Thomas Courtin, Elliott Sherr, Riccardo Parra, Ruth Richardson, Tony Roscioli, Marcello Scala, Celina von Stülpnagel, Damian Smedley, Annalaura Torella, Jun Tohyama, Reiko Koichihara, Keisuke Hamada, Kazuhiro Ogata, Takashi Suzuki, Atsushi Sugie, Jasper J. van der Smagt, Koen van Gassen, Stephanie Valence, Emma Vittery, Stephen Malone, Mitsuhiro Kato, Naomichi Matsumoto, Gian Michele Ratto, Renzo Guerrini, Francesca Pochiero, Francesco Mari, Venkateswaran Ramesh, Valeria Capra, Margherita Mancardi, Boris Keren, Cyiril Mignot, Matteo Lulli, Kendall Parks, Helen Griffin, Melanie Brugger, Vincenzo Nigro, Yuko Hirata, Reiko Koichihara, Borut Peterlin, Yuko Hirata, Ryuto Maki, Yohei Nitta, John C. Ambrose, Prabhu Arumugam, Roel Bevers, Marta Bleda, Freya Boardman-Pretty, Christopher R. Boustred, Helen Brittain, Matthew A. Brown, Mark J. Caulfield, Georgia C. Chan, Adam Giess, John N. Griffin, Angela Hamblin, Shirley Henderson, Tim J.P. Hubbard, Rob Jackson, Louise J. Jones, Dalia Kasperaviciute, Melis Kayikci, Athanasios Kousathanas, Lea Lahnstein, Anna Lakey, Sarah E.A. Leigh, Ivonne U.S. Leong, Javier F. Lopez, Fiona Maleady-Crowe, Meriel McEntagart, Federico Minneci, Jonathan Mitchell, Loukas Moutsianas, Michael Mueller, Nirupa Murugaesu, Anna C. Need, Peter O’Donovan, Chris A. Odhams, Christine Patch, Daniel Perez-Gil, Marina B. Pereira, John Pullinger, Tahrima Rahim, Augusto Rendon, Tim Rogers, Kevin Savage, Kushmita Sawant, Richard H. Scott, Afshan Siddiq, Alexander Sieghart, Samuel C. Smith, Alona Sosinsky, Alexander Stuckey, Mélanie Tanguy, Ana Lisa Taylor Tavares, Ellen R.A. Thomas, Simon R. Thompson, Arianna Tucci, Matthew J. Welland, Eleanor Williams, Katarzyna Witkowska, Suzanne M. Wood, Magdalena Zarowiecki American Journal of Human Genetics, 2023 By converting physical forces into electrical signals or triggering intracellular cascades, stretch-activated ion channels allow the cell to respond to osmotic and mechanical stress. Knowledge of the pathophysiological mechanisms underlying associations of stretch-activated ion channels with human disease is limited. Here, we describe 17 unrelated individuals with severe early-onset developmental and epileptic encephalopathy (DEE), intellectual disability, and severe motor and cortical visual impairment associated with progressive neurodegenerative brain changes carrying ten distinct heterozygous variants of TMEM63B, encoding for a highly conserved stretch-activated ion channel. The variants occurred de novo in 16/17 individuals for whom parental DNA was available and either missense, including the recurrent p.Val44Met in 7/17 individuals, or in-frame, all affecting conserved residues located in transmembrane regions of the protein. In 12 individuals, hematological abnormalities co-occurred, such as macrocytosis and hemolysis, requiring blood transfusions in some. We modeled six variants (p.Val44Met, p.Arg433His, p.Thr481Asn, p.Gly580Ser, p.Arg660Thr, and p.Phe697Leu), each affecting a distinct transmembrane domain of the channel, in transfected Neuro2a cells and demonstrated inward leak cation currents across the mutated channel even in isotonic conditions, while the response to hypo-osmotic challenge was impaired, as were the Ca2+ transients generated under hypo-osmotic stimulation. Ectopic expression of the p.Val44Met and p.Gly580Cys variants in Drosophila resulted in early death. TMEM63B-associated DEE represents a recognizable clinicopathological entity in which altered cation conductivity results in a severe neurological phenotype with progressive brain damage and early-onset epilepsy associated with hematological abnormalities in most individuals.
Somatic Focal Copy Number Gains of Noncoding Regions of Receptor Tyrosine Kinase Genes in Treatment-Resistant Epilepsy Varshini Vasudevaraja, Javier Hernaez Rodriguez, Cristiana Pelorosso, Kaicen Zhu, Anna Maria Buccoliero, Maristela Onozato, Hussein Mohamed, Jonathan Serrano, Lily Tredwin, Marianna Garonzi, Claudio Forcato, Briana Zeck, Sitharam Ramaswami, James Stafford, Arline Faustin, Daniel Friedman, Eveline Teresa Hidalgo, David Zagzag, Jane Skok, Adriana Heguy, Luis Chiriboga, Valerio Conti, Renzo Guerrini, A John Iafrate, Orrin Devinsky, Aristotelis Tsirigos, John G Golfinos, Matija Snuderl Journal of Neuropathology and Experimental Neurology, 2021 Epilepsy is a heterogenous group of disorders defined by recurrent seizure activity due to abnormal synchronized activity of neurons. A growing number of epilepsy cases are believed to be caused by genetic factors and copy number variants (CNV) contribute to up to 5% of epilepsy cases. However, CNVs in epilepsy are usually large deletions or duplications involving multiple neurodevelopmental genes. In patients who underwent seizure focus resection for treatment-resistant epilepsy, whole genome DNA methylation profiling identified 3 main clusters of which one showed strong association with receptor tyrosine kinase (RTK) genes. We identified focal copy number gains involving epidermal growth factor receptor (EGFR) and PDGFRA loci. The dysplastic neurons of cases with amplifications showed marked overexpression of EGFR and PDGFRA, while glial and endothelial cells were negative. Targeted sequencing of regulatory regions and DNA methylation analysis revealed that only enhancer regions of EGFR and gene promoter of PDGFRA were amplified, while coding regions did not show copy number abnormalities or somatic mutations. Somatic focal copy number gains of noncoding regulatory represent a previously unrecognized genetic driver in epilepsy and a mechanism of abnormal activation of RTK genes. Upregulated RTKs provide a potential avenue for therapy in seizure disorders.
Somatic double-hit in MTOR and RPS6 in hemimegalencephaly with intractable epilepsy Cristiana Pelorosso, Françoise Watrin, Valerio Conti, Emmanuelle Buhler, Antoinette Gelot, Xiaoxu Yang, Davide Mei, Jennifer McEvoy-Venneri, Jean-Bernard Manent, Valentina Cetica, Laurel L Ball, Anna Maria Buccoliero, Antonin Vinck, Carmen Barba, Joseph G Gleeson, Renzo Guerrini, Alfonso Represa Human Molecular Genetics, 2019 Single germline or somatic activating mutations of mammalian target of rapamycin (mTOR) pathway genes are emerging as a major cause of type II focal cortical dysplasia (FCD), hemimegalencephaly (HME) and tuberous sclerosis complex (TSC). A double-hit mechanism, based on a primary germline mutation in one allele and a secondary somatic hit affecting the other allele of the same gene in a small number of cells, has been documented in some patients with TSC or FCD. In a patient with HME, severe intellectual disability, intractable seizures and hypochromic skin patches, we identified the ribosomal protein S6 (RPS6) p.R232H variant, present as somatic mosaicism at ~15.1% in dysplastic brain tissue and ~11% in blood, and the MTOR p.S2215F variant, detected as ~8.8% mosaicism in brain tissue, but not in blood. Overexpressing the two variants independently in animal models, we demonstrated that MTOR p.S2215F caused neuronal migration delay and cytomegaly, while RPS6 p.R232H prompted increased cell proliferation. Double mutants exhibited a more severe phenotype, with increased proliferation and migration defects at embryonic stage and, at postnatal stage, cytomegalic cells exhibiting eccentric nuclei and binucleation, which are typical features of balloon cells. These findings suggest a synergistic effect of the two variants. This study indicates that, in addition to single activating mutations and double-hit inactivating mutations in mTOR pathway genes, severe forms of cortical dysplasia can also result from activating mutations affecting different genes in this pathway. RPS6 is a potential novel disease-related gene.
MEK1 is required for the development of NRAS-driven leukemia Joanna D. Nowacka, Christian Baumgartner, Cristiana Pelorosso, Mareike Roth, Johannes Zuber, Manuela Baccarini Oncotarget, 2016 The dual-specificity kinases MEK1 and MEK2 act downstream of RAS/RAF to induce ERK activation, which is generally considered protumorigenic. Activating MEK mutations have not been discovered in leukemia, in which pathway activation is caused by mutations in upstream components such as RAS or Flt3. The anti-leukemic potential of MEK inhibitors is being tested in clinical trials; however, downregulation of MEK1 promotes Eμ-Myc-driven lymphomagenesis and MEK1 ablation induces myeloproliferative disease in mice, raising the concern that MEK inhibitors may be inefficient or counterproductive in this context. We investigated the role of MEK1 in the proliferation of human leukemic cell lines and in retroviral models of leukemia. Our data show that MEK1 suppression via RNA interference and genomic engineering does not affect the proliferation of human leukemic cell lines in culture; similarly, MEK1 ablation does not impact the development of MYC-driven leukemia in vivo. In contrast, MEK1 ablation significantly reduces tumorigenesis driven by Nras alone or in combination with Myc. Thus, while MEK1 restricts proliferation and tumorigenesis in some cellular and genetic contexts, it cannot be considered a tumor suppressor in the context of leukemogenesis. On the contrary, its role in NRAS-driven leukemogenesis advocates the use of MEK inhibitors, particularly in combination with PI3K/AKT inhibitors, in hematopoietic malignancies involving RAS activation.
