Summary
Voltage‐dependent sodium channels consist of a pore‐forming alpha‐subunit and regulatory beta‐subunits. Alterations in these channels have been implicated in temporal lobe epilepsy (TLE) and ...several genetic epilepsy syndromes. Recently we identified Navβ3 as a TLE‐regulated gene. Here we performed a detailed analysis of the hippocampal expression of Navβ3 in TLE patients with hippocampal sclerosis (HS) and without HS (non‐HS) and compared expression with autopsy controls (ACs). Immunoblot analysis showed that Navβ3 levels were dramatically reduced in the hippocampus, but not in the cortex of non‐HS patients when compared to HS patients. This was confirmed by immunohistochemistry showing reduced Navβ3 expression in all principal neurons of the hippocampus proper. Sequence analysis revealed no Navβ3 mutations. The functional consequences of the reduced Navβ3 expression in non‐HS patients are unknown. Altered Navβ3 expression might influence microcircuitry in the hippocampus, affecting excitability and contributing to epileptogenesis in non‐HS patients. Further experiments are required to elucidate these functional possibilities.
Pathogenic variants in KCNB1, encoding the voltage-gated potassium channel K
2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a limited number ...of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell-surface expression.
We evaluated a series of 17 KCNB1 variants associated with DEE or other neurodevelopmental disorders (NDDs) to rapidly ascertain channel dysfunction using high-throughput functional assays. Specifically, we investigated the biophysical properties and cell-surface expression of variant K
2.1 channels expressed in heterologous cells using high-throughput automated electrophysiology and immunocytochemistry-flow cytometry.
Pathogenic variants exhibited diverse functional defects, including altered current density and shifts in the voltage dependence of activation and/or inactivation, as homotetramers or when coexpressed with wild-type K
2.1. Quantification of protein expression also identified variants with reduced total K
2.1 expression or deficient cell-surface expression.
Our study establishes a platform for rapid screening of K
2.1 functional defects caused by KCNB1 variants associated with DEE and other NDDs. This will aid in establishing KCNB1 variant pathogenicity and the mechanism of dysfunction, which will enable targeted strategies for therapeutic intervention based on molecular phenotype. ANN NEUROL 2019;86:899-912.
PurposePathogenic variations in genes encoding aminoacyl-tRNA synthetases (ARSs) are increasingly associated with human disease. Clinical features of autosomal recessive ARS deficiencies appear very ...diverse and without apparent logic. We searched for common clinical patterns to improve disease recognition, insight into pathophysiology, and clinical care.MethodsSymptoms were analyzed in all patients with recessive ARS deficiencies reported in literature, supplemented with unreported patients evaluated in our hospital.ResultsIn literature, we identified 107 patients with AARS, DARS, GARS, HARS, IARS, KARS, LARS, MARS, RARS, SARS, VARS, YARS, and QARS deficiencies. Common symptoms (defined as present in ≥4/13 ARS deficiencies) included abnormalities of the central nervous system and/or senses (13/13), failure to thrive, gastrointestinal symptoms, dysmaturity, liver disease, and facial dysmorphisms. Deep phenotyping of 5 additional patients with unreported compound heterozygous pathogenic variations in IARS,LARS, KARS, and QARS extended the common phenotype with lung disease, hypoalbuminemia, anemia, and renal tubulopathy.ConclusionWe propose a common clinical phenotype for recessive ARS deficiencies, resulting from insufficient aminoacylation activity to meet translational demand in specific organs or periods of life. Assuming residual ARS activity, adequate protein/amino acid supply seems essential instead of the traditional replacement of protein by glucose in patients with metabolic diseases.
Genetic linkage studies have indicated that chromosome 14q24.3 harbours a major locus for early-onset (onset age <65 years) Alzheimer's disease (AD3). Positional cloning efforts have identified a ...novel gene S182 or presenilin 1 as the AD3 gene. We have mapped S182 in the AD3 candidate region between D14S277 and D14S284 defined by genetic linkage studies in the two chromosome 14 linked, early-onset AD families AD/A and AD/B. We have shown that S182 is expressed in lymphoblasts and have determined the complete cDNA in both brain and lymphoblasts by RT-PCR sequencing. S182 is alternatively spliced in both brain and lymphoblasts within a putative phosphorylation site located 5' in the coding region. We identified two novel mutations, Ile143Thr and Gly384la located in, respectively, the second transmembrane domain and in the sixth hydrophilic loop of the putative transmembrane structure of S182. As families AD/A and AD/B have very similar AD phenotype our observation of two mutations in functionally different domains suggest that onset age and severity of AD may not be very helpful predictors of the location of putative S182 mutations.
Summary
FK
506‐binding protein 51 (
FKBP
51) is a co‐chaperone of the glucocorticoid receptor, functionally linked to its activity via an ultra‐short negative feedback loop. Thus,
FKBP
51 plays an ...important regulatory role in the hypothalamic–pituitary–adrenocortical (
HPA
) axis necessary for stress adaptation and recovery. Previous investigations illustrated that
HPA
functionality is influenced by polymorphisms in the gene encoding
FKBP
51, which are associated with both increased protein levels and depressive episodes. Because
FKBP
51 is a key molecule in stress responses, we hypothesized that its deletion impacts sleep. To study
FKBP
51‐involved changes in sleep, polysomnograms of
FKBP
51 knockout (
KO
) mice and wild‐type (
WT
) littermates were compared at baseline and in the recovery phase after 6‐h sleep deprivation (
SD
) and 1‐h restraint stress (
RS
). Using another set of animals, the 24‐h profiles of hippocampal free corticosterone levels were also determined. The most dominant effect of
FKBP
51 deletion appeared as increased nocturnal wake, where the bout length was significantly extended while non‐rapid eye movement sleep (
NREMS
) and rapid eye movement sleep were rather suppressed. After both
SD
and
RS
,
FKBP
51
KO
mice exhibited less recovery or rebound sleep than
WT
s, although slow‐wave activity during
NREMS
was higher in
KO
s, particularly after
SD
. Sleep compositions of
KO
s were nearly opposite to sleep profiles observed in human depression. This might result from lower levels of free corticosterone in
FKBP
51
KO
mice, confirming reduced
HPA
reactivity. The results indicate that an
FKBP
51 deletion yields a pro‐resilience sleep phenotype.
FKBP
51 could therefore be a therapeutic target for stress‐induced mood and sleep disorders.
OBJECTIVEPathogenic variants in KCNB1, encoding the voltage-gated potassium channel KV 2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a ...limited number of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell-surface expression. METHODSWe evaluated a series of 17 KCNB1 variants associated with DEE or other neurodevelopmental disorders (NDDs) to rapidly ascertain channel dysfunction using high-throughput functional assays. Specifically, we investigated the biophysical properties and cell-surface expression of variant KV 2.1 channels expressed in heterologous cells using high-throughput automated electrophysiology and immunocytochemistry-flow cytometry. RESULTSPathogenic variants exhibited diverse functional defects, including altered current density and shifts in the voltage dependence of activation and/or inactivation, as homotetramers or when coexpressed with wild-type KV 2.1. Quantification of protein expression also identified variants with reduced total KV 2.1 expression or deficient cell-surface expression. INTERPRETATIONOur study establishes a platform for rapid screening of KV 2.1 functional defects caused by KCNB1 variants associated with DEE and other NDDs. This will aid in establishing KCNB1 variant pathogenicity and the mechanism of dysfunction, which will enable targeted strategies for therapeutic intervention based on molecular phenotype. ANN NEUROL 2019;86:899-912.
Febrile seizures are the most prevalent type of seizures among children up to 5 years of age (2-4% of Western-European children). Complex febrile seizures are associated with an increased risk to ...develop temporal lobe epilepsy. To investigate short- and long-term effects of experimental febrile seizures (eFS), we induced eFS in highly febrile convulsion-susceptible C57BL/6J mice at post-natal day 10 by exposure to hyperthermia (HT) and compared them to normotherm-exposed (NT) mice. We detected structural re-organization in the hippocampus 14 days after eFS. To identify molecular candidates, which entrain this structural re-organization, we investigated temporal changes in mRNA expression profiles eFS 1 hour to 56 days after eFS. We identified 931 regulated genes and profiled several candidates using in situ hybridization and histology at 3 and 14 days after eFS. This is the first study to report genome-wide transcriptome analysis after eFS in mice. We identify temporal regulation of multiple processes, such as stress-, immune- and inflammatory responses, glia activation, glutamate-glutamine cycle and myelination. Identification of the short- and long-term changes after eFS is important to elucidate the mechanisms contributing to epileptogenesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
Voltage‐dependent sodium channels consist of a pore‐forming alpha‐subunit and regulatory beta‐subunits. Alterations in these channels have been implicated in temporal lobe epilepsy (TLE) and ...several genetic epilepsy syndromes. Recently we identified Na
v
β3 as a TLE‐regulated gene. Here we performed a detailed analysis of the hippocampal expression of Na
v
β3 in TLE patients with hippocampal sclerosis (HS) and without HS (non‐HS) and compared expression with autopsy controls (ACs). Immunoblot analysis showed that Na
v
β3 levels were dramatically reduced in the hippocampus, but not in the cortex of non‐HS patients when compared to HS patients. This was confirmed by immunohistochemistry showing reduced Na
v
β3 expression in all principal neurons of the hippocampus proper. Sequence analysis revealed no Na
v
β3 mutations. The functional consequences of the reduced Na
v
β3 expression in non‐HS patients are unknown. Altered Na
v
β3 expression might influence microcircuitry in the hippocampus, affecting excitability and contributing to epileptogenesis in non‐HS patients. Further experiments are required to elucidate these functional possibilities.
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