ABSTRACT
BACKGROUND: ARF (ADP-ribosylation factor) GTPases are major regulators of intracellular trafficking, and classified into 3 groups (Type I - III), among which the type I group members, ARF1 and 3, are responsible genes for neurodevelopmental disorders. METHODS: In this study, we analysed the expression of Type I ARFs ARF1-3 during mouse brain development using biochemical and morphological methods. RESULTS: Western blotting analyses revealed that ARF1-3 are weakly expressed in the mouse brain at embryonic day 13 and gradually increase until postnatal day 30. ARF1-3 appear to be abundantly expressed in various telencephalon regions. Biochemical fractionation studies detected ARF1-3 in the synaptosome fraction of cortical neurons containing both pre- and post-synapses, however ARF1-3 were not observed in post-synaptic compartments. In immunohistochemical analyses, ARF1-3 appeared to be distributed in the cytoplasm and dendrites of cortical and hippocampal neurons as well as in the cerebellar molecular layer including dendrites of Purkinje cells and granule cell axons. Immunofluorescence in primary cultured hippocampal neurons revealed that ARF1-3 are diffusely distributed in the cytoplasm and dendrites with partial colocalization with a pre-synaptic marker, synaptophysin. CONCLUSIONS: Overall, our results support the notion that ARF1-3 could participate in vesicle trafficking both in the dendritic shaft (excluding spines) and axon terminals (pre-synaptic compartments).
Subject(s)
Monomeric GTP-Binding Proteins , Animals , Mice , ADP-Ribosylation Factors/genetics , Neurons , Axons , CerebellumABSTRACT
BACKGROUND: RAC3 encodes a Rho family small GTPase that regulates the behaviour and organisation of actin cytoskeleton and intracellular signal transduction. Variants in RAC3 can cause a phenotypically heterogeneous neurodevelopmental disorder with structural brain anomalies and dysmorphic facies. The pathomechanism of this recently discovered genetic disorder remains unclear. METHODS: We investigated an early adolescent female with intellectual disability, drug-responsive epilepsy and white matter abnormalities. Through exome sequencing, we identified the novel de novo variant (NM_005052.3): c.83T>C (p.Phe28Ser) in RAC3. We then examined the pathophysiological significance of the p.F28S variant in comparison with the recently reported disease-causing p.Q61L variant, which results in a constitutively activated version of RAC3. RESULTS: In vitro analyses revealed that the p.F28S variant was spontaneously activated by substantially increased intrinsic GTP/GDP-exchange activity and bound to downstream effectors tested, such as PAK1 and MLK2. The variant suppressed the differentiation of primary cultured hippocampal neurons and caused cell rounding with lamellipodia. In vivo analyses using in utero electroporation showed that acute expression of the p.F28S variant caused migration defects of excitatory neurons and axon growth delay during corticogenesis. Notably, defective migration was rescued by a dominant negative version of PAK1 but not MLK2. CONCLUSION: Our results indicate that RAC3 is critical for brain development and the p.F28S variant causes morphological and functional defects in cortical neurons, likely due to the hyperactivation of PAK1.
Subject(s)
Intellectual Disability , Neurodevelopmental Disorders , Adolescent , Humans , Female , Gain of Function Mutation , Neurodevelopmental Disorders/genetics , Neurogenesis , Intellectual Disability/genetics , Cell Differentiation , rac GTP-Binding Proteins/genetics , rac GTP-Binding Proteins/metabolismABSTRACT
Rho family small GTPases, such as Rho, Rac, and Cdc42, play essential roles during brain development, by regulating cellular signaling and actin cytoskeletal reorganization. Rich2/Arhgap44, a Rac- and Cdc42-specific GTPase-activating protein, has been reported to be a key regulator for dendritic spine morphology and synaptic function. Given the essential roles of Rac and Cdc42 in brain development, Rich2 is supposed to take part in brain development. However, not only the molecular mechanism involved but also the expression profile of Rich2 during neurodevelopment has not yet been elucidated. In this study, we carried out expression analyses of Rich2 by focusing on mouse brain development. In immunoblotting, Rich2 exhibited a tissue-dependent expression profile in the young adult mouse, and the expression was increased during brain development. In immunohistochemical analyses, Rich2 was observed in the cytoplasm of cortical neurons at postnatal day (P) 0 and then came to be enriched in the nucleus with moderate distribution in neuropils at P7. Later at P30, a complex immunostaining pattern of Rich2 was observed; Rich2 was distributed in the nucleus, cytoplasm, and neuropils in many cortical neurons, whereas other neurons frequently displayed little expression. In the hippocampus at P7, Rich2 was distributed mainly in the cytoplasm of excitatory neurons in the cornu ammonis regions, while it was moderately detected in the nucleus in the dentate granule cells. Notably, Rich2 was distributed in excitatory synapses of the cornu ammonis 1 region at P30. Biochemical fractionation analyses also detected Rich2 in the postsynaptic density. Taken together, Rich2 is found to be expressed in the central nervous system in a developmental stage-dependent manner and may be involved in synapse formation/maintenance in cortical neurons.
Subject(s)
GTPase-Activating Proteins , Neurons , Mice , Animals , GTPase-Activating Proteins/metabolism , Neurons/metabolism , Hippocampus/metabolism , Synapses/metabolism , NeurogenesisABSTRACT
PURPOSE: Oral administration of 5-aminolevulinic acid hydrochloride (5-ALA-HCl) has been reported to enhance the hypotensive effects associated with anesthetics, especially in elderly hypertensive patients treated with antihypertensive agents. The present study aimed to clarify the effects of antihypertensive-agent- and anesthesia-induced hypotension by 5-ALA-HCl in spontaneously hypertensive rats (SHRs). METHODS: We measured blood pressure (BP) of SHRs and normotensive Wistar Kyoto (WKY) rats treated with amlodipine or candesartan before and after administration of 5-ALA-HCl. We also investigated the change in BP following intravenous infusion of propofol and intrathecal injection of bupivacaine in relation to 5-ALA-HCl administration. FINDINGS: Oral administration of 5-ALA-HCl significantly reduced BP in SHRs and WKY rats with amlodipine and candesartan. Infusion of propofol significantly reduced BP in SHRs treated with 5-ALA-HCl. Intrathecal injection of bupivacaine significantly declined SBP and DBP in both SHRs and WKY rats treated with 5-ALA-HCl. The bupivacaine-induced decline in SBP was significantly larger in SHRs compared with WKY rats. CONCLUSION: These findings suggest that 5-ALA-HCl does not affect the antihypertensive agents-induced hypotensive effect, but enhances the bupivacaine-induced hypotensive effect, especially in SHRs, indicating that 5-ALA may contribute to anesthesia-induced hypotension via suppression of sympathetic nerve activity in patients with hypertension.
Subject(s)
Hypertension , Hypotension, Controlled , Hypotension , Propofol , Rats , Animals , Rats, Inbred SHR , Antihypertensive Agents/adverse effects , Rats, Inbred WKY , Aminolevulinic Acid/adverse effects , Bupivacaine , Propofol/pharmacology , Hypertension/chemically induced , Hypertension/drug therapy , Blood Pressure , Hypotension/chemically induced , Hypotension/drug therapy , Amlodipine/adverse effectsABSTRACT
Variants in RAC3, encoding a small GTPase RAC3 which is critical for the regulation of actin cytoskeleton and intracellular signal transduction, are associated with a rare neurodevelopmental disorder with structural brain anomalies and facial dysmorphism. We investigated a cohort of 10 unrelated participants presenting with global psychomotor delay, hypotonia, behavioural disturbances, stereotyped movements, dysmorphic features, seizures and musculoskeletal abnormalities. MRI of brain revealed a complex pattern of variable brain malformations, including callosal abnormalities, white matter thinning, grey matter heterotopia, polymicrogyria/dysgyria, brainstem anomalies and cerebellar dysplasia. These patients harboured eight distinct de novo RAC3 variants, including six novel variants (NM_005052.3): c.34G > C p.G12R, c.179G > A p.G60D, c.186_188delGGA p.E62del, c.187G > A p.D63N, c.191A > G p.Y64C and c.348G > C p.K116N. We then examined the pathophysiological significance of these novel and previously reported pathogenic variants p.P29L, p.P34R, p.A59G, p.Q61L and p.E62K. In vitro analyses revealed that all tested RAC3 variants were biochemically and biologically active to variable extent, and exhibited a spectrum of different affinities to downstream effectors including p21-activated kinase 1. We then focused on the four variants p.Q61L, p.E62del, p.D63N and p.Y64C in the Switch II region, which is essential for the biochemical activity of small GTPases and also a variation hot spot common to other Rho family genes, RAC1 and CDC42. Acute expression of the four variants in embryonic mouse brain using in utero electroporation caused defects in cortical neuron morphology and migration ending up with cluster formation during corticogenesis. Notably, defective migration by p.E62del, p.D63N and p.Y64C were rescued by a dominant negative version of p21-activated kinase 1. Our results indicate that RAC3 variants result in morphological and functional defects in cortical neurons during brain development through variant-specific mechanisms, eventually leading to heterogeneous neurodevelopmental phenotypes.
Subject(s)
Neurodevelopmental Disorders , rac GTP-Binding Proteins , Animals , Humans , Mice , Neurodevelopmental Disorders/genetics , Neurodevelopmental Disorders/metabolism , Neurons/metabolism , Phenotype , p21-Activated Kinases/genetics , rac GTP-Binding Proteins/genetics , rac GTP-Binding Proteins/metabolismABSTRACT
WAC is an adaptor protein involved in gene transcription, protein ubiquitination, and autophagy. Accumulating evidence indicates that WAC gene abnormalities are responsible for neurodevelopmental disorders. In this study, we prepared anti-WAC antibody, and performed biochemical and morphological characterization focusing on mouse brain development. Western blotting analyses revealed that WAC is expressed in a developmental stage-dependent manner. In immunohistochemical analyses, while WAC was visualized mainly in the perinuclear region of cortical neurons at embryonic day 14, nuclear expression was detected in some cells. WAC then came to be enriched in the nucleus of cortical neurons after birth. When hippocampal sections were stained, nuclear localization of WAC was observed in Cornu ammonis 1 - 3 and dentate gyrus. In cerebellum, WAC was detected in the nucleus of Purkinje cells and granule cells, and possibly interneurons in the molecular layer. In primary cultured hippocampal neurons, WAC was distributed mainly in the nucleus throughout the developing process while it was also localized at perinuclear region at 3 and 7 days in vitro. Notably, WAC was visualized in Tau-1-positive axons and MAP2-positive dendrites in a time-dependent manner. Taken together, results obtained here suggest that WAC plays a crucial role during brain development.
Subject(s)
Neurodevelopmental Disorders , Neurons , Mice , Animals , Neurons/metabolism , Axons , Hippocampus/metabolism , Brain , Neurodevelopmental Disorders/genetics , Neurodevelopmental Disorders/metabolismABSTRACT
Background and Objectives: To examine the relationship between the presence of earlobe crease (EC) and overactive bladder (OAB). Materials and Methods: The earlobes of the participants were examined macroscopically. ECs were further divided into four groups (grades 0-3) according to severity. Subjective symptoms were assessed using the OAB symptom score (OABSS), and objective findings were assessed using uroflowmetry. The relationship between these findings and the presence or absence and severity of EC was also examined. A score of ≥2 points on OABSS question 3 (urinary urgency), with a total score of ≥3 points, indicated OAB. Results: We analyzed 246 participants, including 120 (48.8%) in the EC group and 126 (51.2%) in the non-EC (N-EC) group. On the OABSS, the EC group scored higher than the N-EC group for all questions and for the total score. The total OABSS of EC grade 3 was the highest of all groups. A total of 115 (95.8%) patients in the EC group (100% in grade 3) and 69 (54.8%) in the N-EC group met the OAB criteria (p < 0.001). The voided volume and maximum flow rate of the EC group were significantly lower than those of the N-EC group (both p < 0.001). The post-void residual urine volume in the EC group was significantly higher than that in the N-EC group (p = 0.029). Multivariate analysis revealed that EC was an independent risk factor for OAB (odds ratio, 8.15; 95% confidence interval, 2.84-24.75; p < 0.001). Conclusions: The presence of an earlobe crease may be a predictive marker for OAB.
Subject(s)
Urinary Bladder, Overactive , Humans , Urinary Bladder, Overactive/complications , Urinary Bladder, Overactive/diagnosis , Cross-Sectional Studies , Risk Factors , Multivariate Analysis , Surveys and QuestionnairesABSTRACT
CNKSR2 is a synaptic scaffolding molecule that is encoded by the CNKSR2 gene located on the X chromosome. Heterozygous mutations to CNKSR2 in humans are associated with intellectual disability and epileptic seizures, yet the cellular and molecular roles for CNKSR2 in nervous system development and disease remain poorly characterized. Here, we identify a molecular complex comprising CNKSR2 and the guanine nucleotide exchange factor (GEF) for ARF small GTPases, CYTH2, that is necessary for the proper development of granule neurons in the mouse hippocampus. Notably, we show that CYTH2 binding prevents proteasomal degradation of CNKSR2. Furthermore, to explore the functional significance of coexpression of CNKSR2 and CYTH2 in the soma of granule cells within the hippocampal dentate gyrus, we transduced mouse granule cell precursors in vivo with small hairpin RNAs (shRNAs) to silence CNKSR2 or CYTH2 expression. We found that such manipulations resulted in the abnormal localization of transduced cells at the boundary between the granule cell layer and the hilus. In both cases, CNKSR2-knockdown and CYTH2-knockdown cells exhibited characteristics of immature granule cells, consistent with their putative roles in neuron differentiation. Taken together, our results demonstrate that CNKSR2 and its molecular interaction partner CYTH2 are necessary for the proper development of dentate granule cells within the hippocampus through a mechanism that involves the stabilization of a complex comprising these proteins.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Cell Differentiation , Gene Expression Regulation , Guanine Nucleotide Exchange Factors/metabolism , Hippocampus/metabolism , Neurons/metabolism , Adaptor Proteins, Signal Transducing/genetics , Animals , COS Cells , Chlorocebus aethiops , Gene Knockdown Techniques , Guanine Nucleotide Exchange Factors/genetics , Humans , MiceABSTRACT
Rac3 is a member of Rho family small GTPases which regulate cellular signaling and cytoskeletal dynamics. The RAC3 gene abnormalities have been shown to cause neurodevelopmental disorders with structural brain anomalies, including polymicrogyria/dysgyria, callosal abnormalities, brainstem anomalies, and cerebellar dysplasia. Although this evidence indicates that Rac3 is essential in brain development, not only its molecular mechanism but also the expression profile is yet to be elucidated. In this study, we carried out expression analyses of Rac3 with mouse brain tissues. In immunoblotting, Rac3 exhibited a tissue-dependent expression profile in the young adult mouse and was expressed in a developmental stage-dependent manner in brain. In primary cultured hippocampal neurons, while Rac3 was distributed mainly in the cytoplasm, it was visualized in axon and dendrites with partial localization at synapses, in consistent with the observation in biochemical fractionation analyses. In immunofluorescence analyses with brain slices, Rac3 was distributed strongly and moderately in the axon and cytoplasm, respectively, of cerebral cortex at postnatal day (P) 2 and P18. Similar distribution profile was also observed in hippocampus. Taken together, the results obtained strongly suggest that Rac3 plays an important physiological role in neuronal tissues during corticogenesis, and defects in the Rac3 function induce structural brain anomalies leading to pathogenesis of neurodevelopmental disorders.
Subject(s)
Neurons , rho GTP-Binding Proteins , Animals , Brain/metabolism , Hippocampus/metabolism , Mice , Neurons/metabolism , Synapses/metabolism , rac GTP-Binding Proteins/metabolism , rho GTP-Binding Proteins/metabolismABSTRACT
Centrosomal protein 152 (Cep152) regulates centriole duplication as a molecular scaffold during the cell cycle. Its gene abnormalities are responsible for autosomal recessive primary microcephaly 9 and Seckel syndrome. In this study, we prepared an antibody against mouse Cep152, anti-Cep152, and performed expression analyses focusing on mouse brain development. Western blotting analyses revealed that Cep152 with a molecular mass of â¼150 kDa was expressed strongly at embryonic day (E)13 and then gradually decreased during the brain development process. Instead, protein bands of â¼80 kDa and â¼60 kDa came to be recognized after postnatal day (P)15 and P30, respectively. In immunohistochemical analyses, Cep152 was enriched in the centrosome of neuronal progenitors in the ventricular zone at E14, whereas it was diffusely distributed mainly in the cytoplasm of cortical neurons at P18. In developing cerebellum at P7, Cep152 was localized at the centrosome in the external granular layer, where neurogenesis takes place. Notably, biochemical analysis revealed that Cep152 was also present in the postsynaptic density fraction. Subsequent immunofluorescent analyses showed co-localization of Cep152 with excitatory synaptic markers, PSD95 and synaptophysin, but not with an inhibitory synaptic marker gephyrin in differentiated primary cultured hippocampal neurons. The obtained results suggest that Cep152 takes part not only in neurogenesis during corticogenesis but also in the regulation of synaptic function in differentiated neurons.
Subject(s)
Microcephaly , Animals , Hippocampus/metabolism , Mice , Microcephaly/genetics , Microcephaly/metabolism , Neurogenesis/physiology , Neurons/metabolismABSTRACT
Background and Objectives: To determine changes in the blood pressure (BP) and pulse rate (PR) before and after the administration of mirabegron in real-world clinical practice for patients with overactive bladder (OAB). Materials and Methods: This study was conducted in patients newly diagnosed with OAB. Before and 12 weeks after mirabegron treatment, we evaluated the effects on BP and PR. An overall examination was conducted, and the patients were divided into two groups according to their age: a young group (<65 years old) and an old group (≥65 years old). Results: A total of 263 patients were enrolled in this study. In the overall and intragroup comparisons, the systolic BP (SBP) did not change significantly after mirabegron administration. However, an increase in SBP of ≥10 mmHg was observed in 53 (20.2%), 4 (7.4%), and 49 (23.4%) in the entire group, young group, and old group, respectively (p = 0.009). Regarding diastolic BP, a significant decrease after the treatment was detected in entire (71.2 ± 11.4 versus 69.8 ± 10.7 mmHg; p = 0.041) and old patients (71.5 ± 10.6 versus 69.5 ± 10.2 mmHg; p = 0.012). There was no significant change in PR in our study population. Further examination using a propensity match score revealed that age was the risk factor for the increase in SBP after mirabegron administration. Conclusions: Mirabegron does not have any adverse effects on BP and PR. However, since some patients in this study had elevated SBP after administration, we suggest regular BP monitoring during mirabegron treatment.
Subject(s)
Urinary Bladder, Overactive , Urological Agents , Acetanilides/adverse effects , Aged , Blood Pressure , Heart Rate , Humans , Thiazoles , Treatment Outcome , Urinary Bladder, Overactive/diagnosis , Urinary Bladder, Overactive/drug therapy , Urological Agents/adverse effectsABSTRACT
Mitochondria are key cytoplasmic organelles. Their activation is critical for the generation of T cell proliferation and cytotoxicity. Exhausted tumor-infiltrating T cells show a decreased mitochondrial function and mass. 5-Aminolevulinic acid (5-ALA), a natural amino acid that is only produced in the mitochondria, has been shown to influence metabolic functions. We hypothesized that 5-ALA with sodium ferrous citrate (SFC) might provide metabolic support for tumor-infiltrating T cells. In a mouse melanoma model, we found that 5-ALA/SFC with a programmed cell death-ligand 1 (PD-L1) blocking Ab synergized tumor regression. After treatment with 5-ALA/SFC and anti-PD-L1 Ab, tumor infiltrating lymphocytes (TILs) were not only competent for the production of cytolytic particles and cytokines (granzyme B, interleukin-2, and γ-interferon) but also showed enhanced Ki-67 activity (a proliferation marker). The number of activated T cells (PD-1+ Tim-3- ) was also significantly increased. Furthermore, we found that 5-ALA/SFC activated the mitochondrial functions, including the oxygen consumption rate, ATP level, and complex V expression. The mRNA levels of Nrf-2, HO-1, Sirt-1, and PGC-1α and the protein levels of Sirt-1 were upregulated by treatment with 5-ALA/SFC. Taken together, our findings revealed that 5-ALA/SFC could be a key metabolic regulator in exhausted T cell metabolism and suggested that 5-ALA/SFC might synergize with anti-PD-1/PD-L1 therapy to boost the intratumoral efficacy of tumor-specific T cells. Our study not only revealed a new aspect of immune metabolism, but also paved the way to develop a strategy for combined anti-PD-1/PD-L1 cancer immunotherapy.
Subject(s)
Aminolevulinic Acid/pharmacology , B7-H1 Antigen/antagonists & inhibitors , Citric Acid/pharmacology , Ferrous Compounds/pharmacology , Lymphocyte Activation/drug effects , Lymphocytes, Tumor-Infiltrating/drug effects , Mitochondria/drug effects , Adenosine Triphosphate/metabolism , Animals , Cell Line, Tumor , Combined Modality Therapy , Female , Heme Oxygenase-1/metabolism , Hepatitis A Virus Cellular Receptor 2/metabolism , Ki-67 Antigen/metabolism , Lymphocyte Count , Lymphocytes, Tumor-Infiltrating/cytology , Lymphocytes, Tumor-Infiltrating/metabolism , Melanoma, Experimental/immunology , Melanoma, Experimental/metabolism , Melanoma, Experimental/pathology , Melanoma, Experimental/therapy , Membrane Proteins/metabolism , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mitochondria/metabolism , Nuclear Respiratory Factor 1/metabolism , Oxygen Consumption/drug effects , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Sirtuin 1/metabolismABSTRACT
Abnormalities of PLEKHG2 gene, encoding a Rho family-specific guanine nucleotide exchange factor, are involved in microcephaly with intellectual disability. However, not only the role of PLEKHG2 in the developmental process but also its expression profile is unknown. In this study, we prepared a specific antibody against PLEKHG2 and carried out expression analyses with mouse tissues. In western blotting, PLEKHG2 exhibited a tissue-dependent expression profile in adult mouse and was expressed in a developmental stage-dependent manner in brain. Then, in immunohistochemical analyses, while PLEKHG2 was observed in the cortical plate and ventricular zone surface of the cerebral cortex at embryonic day 14, it came to be distributed throughout the cerebral cortex in layer II/III and V during corticogenesis. PLEKHG2 was also detected mainly in the nucleus of neurons in the hippocampal CA regions and dentate gyrus at P7. Notably, the nuclear accumulation disappeared at P30 and PLEKHG2 came to be located at the axons and/or dendrites at this time point. Moreover, in vitro immunofluorescence revealed that PLEKHG2 was at least partially localized at both excitatory and inhibitory synapses in primary cultured hippocampal neurons. These results suggest roles of PLEKHG2 in the development of the central nervous tissue and synaptic function.
Subject(s)
Brain/metabolism , Gene Expression Regulation, Developmental , Guanine Nucleotide Exchange Factors/genetics , Neurons/metabolism , Animals , Brain/growth & development , COS Cells , Cell Line , Cell Line, Tumor , Chlorocebus aethiops , Hippocampus/growth & development , Hippocampus/metabolism , Immunohistochemistry , Mice , Organ SpecificityABSTRACT
Takenouchi-Kosaki syndrome (TKS) is an autosomal dominant congenital syndrome, of which pathogenesis is not well understood. Recently, a heterozygous mutation c.1449T > C/p.(Tyr64Cys) in the CDC42 gene, encoding a Rho family small GTPase, has been demonstrated to contribute to the TKS clinical features, including developmental delay with intellectual disability (ID). However, specific molecular mechanisms underlying the neuronal pathophysiology of TKS remain largely unknown. In this study, biochemical analyses revealed that the mutation moderately activates Cdc42. In utero electroporation-based acute expression of Cdc42-Y64C in ventricular zone progenitor cells in embryonic mice cerebral cortex resulted in migration defects and cluster formation of excitatory neurons. Expression the mutant in primary cultured hippocampal neurons caused impaired axon elongation. These data suggest that the c.1449T > C/p.(Tyr64Cys) mutation causes altered CDC42 function and results in defects in neuronal morphology and migration during brain development, which is likely to be responsible for pathophysiology of psychomotor delay and ID in TKS.
Subject(s)
Brain/pathology , Brain/physiopathology , Genetic Predisposition to Disease , Mutation/genetics , Polymorphism, Single Nucleotide/genetics , cdc42 GTP-Binding Protein/genetics , Animals , Axons/metabolism , COS Cells , Cell Aggregation , Cell Movement , Cells, Cultured , Cerebral Cortex , Chlorocebus aethiops , Hippocampus/pathology , Mice, Inbred ICR , Mutant Proteins/metabolism , Neurites/metabolism , Organogenesis , SyndromeABSTRACT
BACKGROUND: In this study, we aimed to identify the gene abnormality responsible for pathogenicity in an individual with an undiagnosed neurodevelopmental disorder with megalencephaly, ventriculomegaly, hypoplastic corpus callosum, intellectual disability, polydactyly and neuroblastoma. We then explored the underlying molecular mechanism. METHODS: Trio-based, whole-exome sequencing was performed to identify disease-causing gene mutation. Biochemical and cell biological analyses were carried out to elucidate the pathophysiological significance of the identified gene mutation. RESULTS: We identified a heterozygous missense mutation (c.173C>T; p.Thr58Met) in the MYCN gene, at the Thr58 phosphorylation site essential for ubiquitination and subsequent MYCN degradation. The mutant MYCN (MYCN-T58M) was non-phosphorylatable at Thr58 and subsequently accumulated in cells and appeared to induce CCND1 and CCND2 expression in neuronal progenitor and stem cells in vitro. Overexpression of Mycn mimicking the p.Thr58Met mutation also promoted neuronal cell proliferation, and affected neuronal cell migration during corticogenesis in mouse embryos. CONCLUSIONS: We identified a de novo c.173C>T mutation in MYCN which leads to stabilisation and accumulation of the MYCN protein, leading to prolonged CCND1 and CCND2 expression. This may promote neurogenesis in the developing cerebral cortex, leading to megalencephaly. While loss-of-function mutations in MYCN are known to cause Feingold syndrome, this is the first report of a germline gain-of-function mutation in MYCN identified in a patient with a novel megalencephaly syndrome similar to, but distinct from, CCND2-related megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome. The data obtained here provide new insight into the critical role of MYCN in brain development, as well as the consequences of MYCN defects.
Subject(s)
Gain of Function Mutation , Genetic Association Studies , Genetic Predisposition to Disease , Megalencephaly/diagnosis , Megalencephaly/genetics , N-Myc Proto-Oncogene Protein/genetics , Adolescent , Alleles , Animals , Brain/abnormalities , DNA Mutational Analysis , Disease Models, Animal , Facies , Genotype , HEK293 Cells , Humans , Magnetic Resonance Imaging , Male , Mice , Neural Stem Cells/cytology , Neural Stem Cells/metabolism , Pedigree , Phenotype , Radiography , Syndrome , Exome SequencingABSTRACT
Septins are a highly conserved family of GTPases which are identified in diverse organisms ranging from yeast to humans. In mammals, nervous tissues abundantly contain septins and associations of septins with neurological disorders such as Alzheimer's disease and Parkinson's disease have been reported. However, roles of septins in the brain development have not been fully understood. In this study, we produced a specific antibody against mouse SEPT1 and carried out biochemical and morphological characterization of SEPT1. When the expression profile of SEPT1 during mouse brain development was analyzed by western blotting, we found that SEPT1 expression began to increase after birth and the increase continued until postnatal day 22. Subcellular fractionation of mouse brain and subsequent western blot analysis revealed the distribution of SEPT1 in synaptic fractions. Immunofluorescent analyses showed the localization of SEPT1 at synapses in primary cultured mouse hippocampal neurons. We also found the distribution of SEPT1 at synapses in mouse brain by immunohistochemistry. These results suggest that SEPT1 participates in various synaptic events such as the signaling, the neurotransmitter release, and the synapse formation/maintenance.
Subject(s)
Gene Expression Regulation, Developmental , Hippocampus/growth & development , Septins/metabolism , Animals , Animals, Newborn , COS Cells , Chlorocebus aethiops , Embryo, Mammalian , Gene Expression Profiling , Hippocampus/cytology , Hippocampus/metabolism , Immunohistochemistry , Male , Mice , Neurons/metabolism , Primary Cell Culture , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Septins/analysis , Septins/genetics , Signal Transduction/genetics , Synapses/metabolismABSTRACT
The hippocampus is generally considered as a brain center for learning and memory. We have recently established an electroporation-mediated gene transfer method to investigate the development of neonatal dentate granule cells in vivo. Using this new technique, we introduced knockdown vectors against Rac1 small GTPase into precursors for dentate granule cells at postnatal day 0. After 21 days, Rac1-deficient cells were frequently mispositioned between the granule cell layer (GCL) and hilus. About 60% of these mislocalized cells expressed a dentate granule cell marker, Prox1. Both the dendritic spine density and the ratio of mature spine were reduced when Rac1 was silenced. Notably, the deficient cells have immature thin processes during migrating in the early neonatal period. Knockdown of another Rac isoform, Rac3, also resulted in mislocalization of neonatally born dentate granule cells. In addition, knockdown of Cdc42, another Rho family protein, also caused mislocalization of the cell, although the effects were moderate compared to Rac1 and 3. Despite the ectopic localization, Rac3- or Cdc42-disrupted mispositioned cells expressed Prox1. These results indicate that Rho signaling pathways differentially regulate the proper localization and differentiation of dentate granule cells.
Subject(s)
Dentate Gyrus/enzymology , Dentate Gyrus/growth & development , Neuropeptides/metabolism , cdc42 GTP-Binding Protein/metabolism , rac GTP-Binding Proteins/metabolism , rac1 GTP-Binding Protein/metabolism , Animals , Animals, Newborn , Cell Differentiation , Cell Movement , Dentate Gyrus/cytology , Gene Knockdown Techniques , Gene Transfer Techniques , Homeodomain Proteins/metabolism , Mice , Mice, Inbred ICR , Neurogenesis , Neuropeptides/deficiency , Neuropeptides/genetics , RNA Interference , Signal Transduction , Tumor Suppressor Proteins/metabolism , cdc42 GTP-Binding Protein/deficiency , cdc42 GTP-Binding Protein/genetics , rac GTP-Binding Proteins/deficiency , rac GTP-Binding Proteins/genetics , rac1 GTP-Binding Protein/deficiency , rac1 GTP-Binding Protein/geneticsABSTRACT
BACKGROUND: Cyclosporine-A (CsA) is an immunosuppressant indicated for various immunological diseases; however, it can induce chronic kidney injury. Oxidative stress and apoptosis play a crucial role in CsA-induced nephrotoxicity. The present study evaluated the protective effect of combining 5-aminolaevulinic acid with iron (5-ALA/SFC), a precursor of heme synthesis, to enhance HO-1 activity against CsA-induced chronic nephrotoxicity. METHODS: Mice were divided into three groups: the control group (using olive oil as a vehicle), CsA-only group, and CsA+5-ALA/SFC group. After 28 days, the mice were sacrificed, and blood and kidney samples were collected. In addition to histological and biochemical examination, the mRNA expression of proinflammatory and profibrotic cytokines was assessed. RESULTS: Renal function in the 5-ALA/SFC treatment group as assessed by the serum creatinine and serum urea nitrogen levels was superior to that of the CsA-only treatment group, demonstrating that 5-ALA/SFC significantly attenuated CsA-induced kidney tissue inflammation, fibrosis, apoptosis, and tubular atrophy, as well as reducing the mRNA level of TNF-α, IL-6, TGF-ß1, and iNOS while increasing HO-1. CONCLUSION: The activity of 5-ALA/SFC has important implications for clarifying the mechanism of HO-1 activity in CsA-induced nephrotoxicity and may provide a favorable basis for clinical therapy.
Subject(s)
Cyclosporine/adverse effects , Fibrosis/prevention & control , Heme Oxygenase-1/metabolism , Levulinic Acids/pharmacology , Nephritis, Interstitial/pathology , Nephritis, Interstitial/prevention & control , Animals , Apoptosis/drug effects , Atrophy/prevention & control , Cytokines/genetics , Drug Therapy, Combination , Heme Oxygenase-1/drug effects , Inflammation/prevention & control , Iron/pharmacology , Iron/therapeutic use , Levulinic Acids/therapeutic use , Mice , Nephritis, Interstitial/chemically induced , Oxidative Stress/drug effects , RNA, Messenger/analysis , Aminolevulinic AcidABSTRACT
POGZ is a heterochromatin protein 1 α-binding protein and regulates gene expression. On the other hand, accumulating pieces of evidence indicate that the POGZ gene abnormalities are involved in various neurodevelopmental disorders. In this study, we prepared a specific antibody against POGZ, anti-POGZ, and carried out biochemical and morphological characterization with mouse brain tissues. Western blotting analyses revealed that POGZ is expressed strongly at embryonic day 13 and then gradually decreased throughout the brain development process. In immunohistochemical analyses, POGZ was found to be enriched in cerebrocortical and hippocampal neurons in the early developmental stage. The nuclear expression was also detected in Purkinje cells in cerebellum at postnatal day (P)7 and P15 but disappeared at P30. In primary cultured hippocampal neurons, while POGZ was distributed mainly in the nucleus, it was also visualized in axon and dendrites with partial localization at synapses in consistency with the results obtained in biochemical fractionation analyses. The obtained results suggest that POGZ takes part in the regulation of synaptic function as well as gene expression during brain development.
Subject(s)
Brain/metabolism , Neurogenesis/physiology , Transposases/metabolism , Animals , Brain/embryology , Brain/growth & development , Gene Expression Regulation, Developmental/physiology , Mice , Neurodevelopmental Disorders/genetics , Neurodevelopmental Disorders/metabolismABSTRACT
BACKGROUND: This study aimed to investigate the protective effect of 5-aminolevulinic acid (5-ALA) and sodium ferrous citrate (SFC) against binge alcohol-induced gut leakiness and inflammatory liver disease in HIV transgenic (TG) rats. METHODS: TG rats were treated with 3 consecutive doses of binge ethanol (EtOH) with or without 5-ALA/SFC. Blood and liver tissue samples were collected at 6 hours following the last dose of EtOH. RESULTS: Compared with the wild-type (WT) rats, the TG rats showed increased sensitivity to alcohol-mediated inflammation, as evidenced by the significantly elevated levels of serum endotoxin, AST, ALT, ED1, and ED2 staining in liver. In contrast, 5-ALA/SFC improved the above biochemical and histochemical profiles. 5-ALA/SFC also attenuated the up-regulated mRNA expression of leptin and CCL2. Furthermore, down-regulated intestinal ZO-1 protein expression was also inhibited by 5-ALA/SFC. Moreover, the expressions of HO-1, HO-2, Sirt1, and related signal transduction molecules in liver were increased by 5-ALA/SFC. These results demonstrated that 5-ALA/SFC treatment ameliorated binge alcohol exposure liver injury in a rat model of HIV-infected patients by reducing macrophage activation and expression of inflammatory cytokines/chemokines, and by inducing HO-1, HO-2, and Sirt1 expression. CONCLUSIONS: Taken together, these findings suggested that treatment with 5-ALA/SFC has a potential therapeutic effect for binge alcohol exposure liver injury in HIV-infected patients.