Background: Ictal bradycardia (IB) and asystole (IA) represent a rare but potentially harmful feature of epileptic seizures. The aim of this study was to study IB/IA in patients with sleep-related hypermotor epilepsy (SHE). Methods: We retrospectively included cases with video-EEG-confirmed SHE who attended our Institute up to January 2021. We reviewed the ictal polysomnography recordings focusing on ECG and identified cases with IB (R-R interval ≥ 2 s or a ≥10% decrease of baseline heart rate) and IA (R-R interval ≥ 4 s). Results: We included 200 patients (123 males, 61.5%), with a mean age of 42 ± 16 years. Twenty patients (20%) had focal cortical dysplasia (FCD) on brain MRI. Eighteen (out of 104 tested, 17.3%) carried pathogenic variants (mTOR pathway, n = 10, nAchR subunits, n = 4, KCNT1, n = 4). We identified IB/IA in four cases (2%): three had IA (mean 10 s) and one had IB. Three patients had FCD (left fronto-insular region, left amygdala, right mid-temporal gyrus) and two had pathogenic variants in DEPDC5; both features were more prevalent in patients with IB/IA than those without (p = 0.003 and p = 0.037, respectively). Conclusions: We identified IB/IA in 2% of patients with SHE and showed that this subgroup more frequently had FCD on brain MRI and pathogenic variants in genes related to the mTOR pathway.

Regulation of mechanistic target of rapamycin complex 1 (mTORC1) plays an important role in aging and nutrition. For example, caloric restriction reduces mTORC1 signaling and extends lifespan, whereas nutrient abundance and obesity increase mTORC1 signaling and reduce lifespan. Skeletal muscle-specific knockout (KO) of DEP domain-containing 5 protein (DEPDC5) results in constitutively active mTORC1 signaling, muscle hypertrophy and an increase in mitochondrial respiratory capacity. The metabolic profile of skeletal muscle, in the setting of hyperactive mTORC1 signaling, is not well known.
To determine the metabolomic and lipidomic signature in skeletal muscle from female and male wild-type (WT) and DEPDC5 KO mice.
Tibialis anterior (TA) muscles from WT and transgenic (conditional skeletal muscle-specific DEPDC5 KO) were obtained from female and male adult mice. Polar metabolites and lipids were extracted using a Bligh-Dyer extraction from 5 samples per group and identified and quantified by LC-MS/MS. Resulting analyte peak areas were analyzed with t-test, analysis of variance, and Volcano plots for group comparisons (e.g., WT compared with KO) and multivariate statistical analysis for genotype and sex comparisons.
A total of 162 polar metabolites (organic acids, amino acids, and amines and acyl carnitines) and 1141 lipid metabolites were detected in TA samples by LC-MS/MS. Few polar metabolites showed significant differences in KO muscles compared with WT within the same sex group. P-aminobenzoic acid, β-alanine, and dopamine were significantly higher in KO male muscle whereas erythrose-4-phosphate and oxoglutaric acid were significantly reduced in KO females. The lipidomic profile of the KO groups revealed an increase of muscle phospholipids and reduced triacylglycerol and diacylglycerol compared with the WT groups.
Sex differences were detected in polar metabolome and lipids were dependent on genotype. The metabolomic profile of mice with hyperactive skeletal muscle mTORC1 is consistent with an upregulation of mitochondrial function and amino acid utilization for protein synthesis.

Colorectal cancer (CRC) is a devastating disease that is highly modulated by dietary nutrients. Mechanistic target of rapamycin complex 1 (mTORC1) contributes to tumor growth and limits therapy responses. Growth factor signaling is a major mechanism of mTORC1 activation. However, compensatory pathways exist to sustain mTORC1 activity after therapies that target oncogenic growth factor signaling. Amino acids potently activate mTORC1 via amino acid-sensing GTPase activity towards Rags (GATOR). The role of amino acid-sensing pathways in CRC is unclear.
Human colon cancer cell lines, preclinical intestinal epithelial-specific GATOR1 and GATOR2 knockout mice subjected to colitis-induced or sporadic colon tumor models, small interfering RNA screening targeting regulators of mTORC1, and tissues of patients with CRC were used to assess the role of amino acid sensing in CRC.
We identified loss-of-function mutations of the GATOR1 complex in CRC and showed that altered expression of amino acid-sensing pathways predicted poor patient outcomes. We showed that dysregulated amino acid-sensing induced mTORC1 activation drives colon tumorigenesis in multiple mouse models. We found amino acid-sensing pathways to be essential in the cellular reprogramming of chemoresistance, and chemotherapeutic-resistant patients with colon cancer exhibited de-regulated amino acid sensing. Limiting amino acids in in vitro and in vivo models (low-protein diet) reverted drug resistance, revealing a metabolic vulnerability.
Our findings suggest a critical role for amino acid-sensing pathways in driving CRC and highlight the translational implications of dietary protein intervention in CRC.

BACKGROUND: Variants in the DEPDC5 have been proved to be main cause of not only various dominant familial focal epilepsies, but also sporadic focal epilepsies. In the present study, a novel variant in DEPDC5 was detected in the patient with focal epilepsy and his healthy father. We aimed to analyze the pathogenic DEPDC5 variant in the small family of three.
METHODS: A 5-month-old male infant presented with focal epilepsy. Whole exome sequencing identified a novel heterozygous variant c.1696delC (p.Gln566fs) in DEPDC5, confirmed by Sanger sequencing. The variant was inherited from healthy father.
CONCLUSIONS: Our study expands the spectrum of DEPDC5 variants. Moreover, We discuss the relation between the low penetrance of DEPDC5 and the relatively high morbidity rate of DEPDC5-related sporadic focal epilepsy. Besides, due to interfamilial phenotypic and genetic heterogeneity, we speculate the prevalence of familial focal epilepsy with variable foci might be underestimated in such small families. We emphasize the importance of gene detection in patients with sporadic epilepsy of unknown etiology, as well as their family members. It can identify causative mutations, thus providing help to clinicians in making a definitive diagnosis.

Epilepsy with auditory features (EAF) is a focal epilepsy belonging to the focal epileptic syndromes with onset at variable age according to the new ILAE Classification. It is characterized by seizures with auditory aura or receptive aphasia suggesting a lateral temporal lobe involvement of the epileptic discharge. Etiological factors underlying EAF are largely unknown. In the familial cases with an autosomal dominant pattern of inheritance several genes have been involved, among which the first discovered, LGI1, was thought to be predominant. However, increasing evidence now points to a multifactorial etiology, as familial and sporadic EAF share a virtually identical electro-clinical characterization and only a few have a documented genetic etiology. Patients with EAF usually have an unremarkable neurological examination and a good response to antiseizure medications. However, it must be underscored that total remission might be lower than expected and that treatment withdrawal might lead to relapses. Thus, a proper understanding of this condition is in order for better patient treatment and counseling. Further studies are still required to further characterize the many facets of EAF.

The mammalian target of rapamycin complex 1 (mTORC1) is a crucial regulator of adipogenesis and systemic energy metabolism. Its dysregulation leads to a diversity of metabolic diseases, including obesity and type 2 diabetes. DEP-domain containing 5 (DEPDC5) is a critical component of GATOR1 complex that functions as a key inhibitor of mTORC1. So far, its function in adipose tissue remains largely unknown. Herein we evaluated how persistent mTORC1 activation in adipocyte via Depdc5 knockout modulates adiposity in vivo. Our data indicated that adipocyte-specific knockout of Depdc5 in aged mice led to reduced visceral fat, aggravated insulin resistance and enhanced adipose tissue inflammation. Moreover, we found that Depdc5 ablation resulted in upregulation of adipose triglyceride lipase (ATGL) in adipocytes and elevated levels of serum free fatty acids (FFAs). Intriguingly, rapamycin treatment did not reverse insulin resistance but alleviated adipose tissue inflammation caused by Depdc5 deletion. Taken together, our findings revealed that mTORC1 activation caused by Depdc5 deletion promotes lipolysis process and further exacerbates insulin resistance and adipose tissue inflammation in mice.

Mutations in the disheveled, Egl-10 and domain-containing protein 5 (DEPDC5) recently have been identified as a common cause of focal epilepsy syndromes. The association between phenotype and genotype of DEPDC5 mutation has not been adequately characterized. We studied four families with familial focal epilepsy carrying DEPDC5 mutations. Four novel DEPDC5 mutations were identified by next-generation sequencing, including two missense mutations (c.1729 >A and c.3260G>A), one splicing mutation (c.280-1G>A), and one frameshift mutation (c.515_516delinsT). We found that patients carrying different DEPDC5 mutation have different clinical manifestations. Incomplete penetrance is a prominent feature of DEPDC5-related epilepsy, with the rate of penetrance ranging from 25 to 100%. About 21.4% of patients with DEPDC5-related familial focal epilepsy are refractory to treatments. We further reviewed the correlation of genotype and phenotype in all previous literature regarding DEPDC5-related epilepsy. Our study suggested that the type of DEPDC5 mutation might provide important information for the prognosis evaluation.

Efficient genetic manipulation in the developing central nervous system is crucial for investigating mechanisms of neurodevelopmental disorders and the development of promising therapeutics. Common approaches including transgenic mice and in utero electroporation, although powerful in many aspects, have their own limitations. In this study, we delivered vectors based on the AAV9.PHP.eB pseudo-type to the fetal mouse brain, and achieved widespread and extensive transduction of neural cells. When AAV9.PHP.eB-coding gRNA targeting PogZ or Depdc5 was delivered to Cas9 transgenic mice, widespread gene knockout was also achieved at the whole brain level. Our studies provide a useful platform for studying brain development and devising genetic intervention for severe developmental diseases.

To explore the phenotype spectrum of DEPDC5 variants and the possible mechanisms underlying phenotypical variation, we performed targeted next-generation sequencing in 305 patients with focal epilepsies and 91 patients with generalized epilepsies. Protein modeling was performed to predict the effects of missense mutations. All previously reported epilepsy-related DEPDC5 variants were reviewed. The genotype-phenotype correlations with molecular sub-regional implications were analyzed. We identified a homozygous DEPDC5 mutation (p.Pro1031His) in a case with focal cortical dysplasia and eight heterozygous mutations in 11 families with mild focal epilepsies, including 13 patients in eight families with focal epilepsy with febrile seizures plus/febrile seizures (FEFS + /FS). The mutations included one termination codon mutation (p.Ser1601_Ter1604del_ext133), three truncating mutations (p.Val151Serfs∗27, p.Arg239∗, and p.Arg838∗), and four missense mutations (p.Tyr7Cys, p.Tyr836Cys, p.Pro1031His, and p.Gly1545Ser) that were predicted to affect hydrogen bonds and protein stability. Analysis on epilepsy-related DEPDC5 variants revealed that malformations of cortical development (MCDs) had a tendency of higher frequency of null mutations than those without MCD. MCD-associated heterozygous missense mutations were clustered in structural axis for binding arrangement (SABA) domain and close to the binding sites to NPRL2/NPRL3 complex, whereas those associated with FEFS + /FS were a distance away from the binding sites. Evidence from four aspects and one possible evidence from sub-regional implication suggested MCD and FEFS + /FS as phenotypes of DEPDC5 variants. This study suggested that the phenotypes of DEPDC5 variants vary from mild FEFS + /FS to severe MCD. Heterozygous DEPDC5 mutations are generally less pathogenic and commonly associated with mild phenotypes. Bi-allelic mutations and second hit of somatic mutations, together with the genotype-phenotype correlation and sub-regional implication of DEPDC5 variants, explain severe phenotypes.

DEP-domain containing 5 (DEPDC5) is part of the GATOR1 complex that functions as key inhibitor of the mechanistic target of rapamycin complex 1 (mTORC1). Loss-of-function mutations in DEPDC5 leading to mTOR hyperactivation have been identified as the most common cause of either lesional or non-lesional focal epilepsy. However, the precise mechanisms by which DEPDC5 loss-of-function triggers neuronal and network hyperexcitability are still unclear. In this study, we investigated the cellular mechanisms of hyperexcitability by comparing the constitutive heterozygous Depdc5 knockout mouse versus different levels of acute Depdc5 deletion (≈40% and ≈80% neuronal knockdown of Depdc5 protein) by RNA interference in primary cortical cultures. While heterozygous Depdc5+/- neurons have only a subtle phenotype, acutely knocked-down neurons exhibit a strong dose-dependent phenotype characterized by mTOR hyperactivation, increased soma size, dendritic arborization, excitatory synaptic transmission and intrinsic excitability. The robust synaptic phenotype resulting from the acute knockdown Depdc5 deficiency highlights the importance of the temporal dynamics of Depdc5 knockdown in triggering the phenotypic changes, reminiscent of the somatic second-hit mechanism in patients with focal cortical dysplasia. These findings uncover a novel synaptic phenotype that is causally linked to Depdc5 knockdown, highlighting the developmental role of Depdc5. Interestingly, the synaptic defect appears to affect only excitatory synapses, while inhibitory synapses develop normally. The increased frequency and amplitude of mEPSCs, paralleled by increased density of excitatory synapses and expression of glutamate receptors, may generate an excitation/inhibition imbalance that triggers epileptogenesis.