A Kirchner1, S Bagla2, F Dachet3, J A Loeb4. 1. University of Illinois at Chicago, Department of Neurology and Rehabilitation, 912 S Wood Street, Chicago, IL 60612, United States of America. 2. Wayne State University, Department of Pediatrics, Children's Hospital of Michigan, 3901 Beaubien Blvd., Detroit, MI 48201, United States of America. 3. University of Illinois at Chicago, Department of Neurology and Rehabilitation, 912 S Wood Street, Chicago, IL 60612, United States of America; University of Illinois at Chicago, University of Illinois Neuro-Repository, 912 S Wood Street, Chicago, IL 60612, United States of America. 4. University of Illinois at Chicago, Department of Neurology and Rehabilitation, 912 S Wood Street, Chicago, IL 60612, United States of America; University of Illinois at Chicago, University of Illinois Neuro-Repository, 912 S Wood Street, Chicago, IL 60612, United States of America. Electronic address: jaloeb@uic.edu.
Abstract
BACKGROUND: We previously identified the Mitogen Activated Protein Kinase (MAPK) pathway as focally upregulated in brain regions with high epileptic activity and showed that inhibition of MAPK signaling reduces epileptic spiking in an animal model. Here we examined how activators and inhibitors of the MAPK pathway are expressed in human epileptic cortex and how these could contribute to the localization of epileptic signaling. METHODS: We localized gene and protein expression in human epileptic neocortical tissues based on epileptic activities from 20 patients based on long-term intracranial recordings. Follow-up mechanistic studies by depolarization of human Sh-SY5Y cell line were used to model epileptic activity in the human brain. RESULTS: A clustering algorithm of differentially expressed genes identified a unique gene expression cluster distinct from other MAPK genes. Within this cluster was dual specificity phosphatase 4 (DUSP4), a potent MAPK inhibitor. In situ hybridization studies revealed focal patches of DUSP4 mRNA in layer 2/3 brain regions associated with a dramatic reduction in MAPK signaling genes. In vitro depolarization led to the rapid and transient induction of DUSP4 protein, which, in turn, reduced MAPK activity. Activity-dependent induction of DUSP4 protein was transient and required MAPK signaling. Human epileptic brain regions with lower epileptic activity had lower MAPK activity and higher DUSP4 protein levels. DISCUSSION: DUSP4 is a highly localized, endogenous feedback inhibitor of pro-epileptogenic MAPK signaling in the human epileptic brain. Increasing DUSP4 expression could therefore be a novel therapeutic approach to prevent the development and spread of epileptic circuits. SIGNIFICANCE STATEMENT: Epilepsy is a chronic debilitating disease. Once it develops, epileptic circuits often persist throughout life. Fortunately, in focal forms of epilepsy, these circuits can remain highly localized and are amenable to surgical resections, suggesting that endogenous mechanisms restrict their spread to other brain regions. Using a high-throughput genomic analysis of human epileptic brain regions, we identified DUSP4 as an activity-dependent inhibitor of MAPK signaling expressed in focal patches surrounding human neocortical epileptic brain regions. Our results suggest that DUSP4, through local inhibition of MAPK signaling, acts as an endogenous, spatially segregated safety mechanism to prevent the spread of epileptic activity. Augmenting DUSP4 expression could be a novel disease-modifying approach to prevent or treat human epilepsy.
BACKGROUND: We previously identified the Mitogen Activated Protein Kinase (MAPK) pathway as focally upregulated in brain regions with high epileptic activity and showed that inhibition of MAPK signaling reduces epileptic spiking in an animal model. Here we examined how activators and inhibitors of the MAPK pathway are expressed in humanepileptic cortex and how these could contribute to the localization of epileptic signaling. METHODS: We localized gene and protein expression in humanepileptic neocortical tissues based on epileptic activities from 20 patients based on long-term intracranial recordings. Follow-up mechanistic studies by depolarization of humanSh-SY5Y cell line were used to model epileptic activity in the human brain. RESULTS: A clustering algorithm of differentially expressed genes identified a unique gene expression cluster distinct from other MAPK genes. Within this cluster was dual specificity phosphatase 4 (DUSP4), a potent MAPK inhibitor. In situ hybridization studies revealed focal patches of DUSP4 mRNA in layer 2/3 brain regions associated with a dramatic reduction in MAPK signaling genes. In vitro depolarization led to the rapid and transient induction of DUSP4 protein, which, in turn, reduced MAPK activity. Activity-dependent induction of DUSP4 protein was transient and required MAPK signaling. Humanepileptic brain regions with lower epileptic activity had lower MAPK activity and higher DUSP4 protein levels. DISCUSSION: DUSP4 is a highly localized, endogenous feedback inhibitor of pro-epileptogenic MAPK signaling in the humanepileptic brain. Increasing DUSP4 expression could therefore be a novel therapeutic approach to prevent the development and spread of epileptic circuits. SIGNIFICANCE STATEMENT: Epilepsy is a chronic debilitating disease. Once it develops, epileptic circuits often persist throughout life. Fortunately, in focal forms of epilepsy, these circuits can remain highly localized and are amenable to surgical resections, suggesting that endogenous mechanisms restrict their spread to other brain regions. Using a high-throughput genomic analysis of humanepileptic brain regions, we identified DUSP4 as an activity-dependent inhibitor of MAPK signaling expressed in focal patches surrounding human neocortical epileptic brain regions. Our results suggest that DUSP4, through local inhibition of MAPK signaling, acts as an endogenous, spatially segregated safety mechanism to prevent the spread of epileptic activity. Augmenting DUSP4 expression could be a novel disease-modifying approach to prevent or treat humanepilepsy.
Authors: Helen C Wu; Fabien Dachet; Farhad Ghoddoussi; Shruti Bagla; Darren Fuerst; Jeffrey A Stanley; Matthew P Galloway; Jeffrey A Loeb Journal: Epilepsia Date: 2017-07-17 Impact factor: 5.864
Authors: J S Sebolt-Leopold; D T Dudley; R Herrera; K Van Becelaere; A Wiland; R C Gowan; H Tecle; S D Barrett; A Bridges; S Przybranowski; W R Leopold; A R Saltiel Journal: Nat Med Date: 1999-07 Impact factor: 53.440
Authors: Antonio M Grimaldi; Ester Simeone; Lucia Festino; Vito Vanella; Martina Strudel; Paolo A Ascierto Journal: Am J Clin Dermatol Date: 2017-12 Impact factor: 7.403
Authors: Fabien Dachet; James B Brown; Tibor Valyi-Nagy; Kunwar D Narayan; Anna Serafini; Nathan Boley; Thomas R Gingeras; Susan E Celniker; Gayatry Mohapatra; Jeffrey A Loeb Journal: Sci Rep Date: 2021-03-23 Impact factor: 4.996