An N-terminal and ankyrin repeat domain interactome of Shank3 identifies the protein complex with the splicing regulator Nono in mice.

An autism-associated gene Shank3 encodes multiple splicing isoforms, Shank3a-f. We have recently reported that Shank3a/b-knockout mice were more susceptible to kainic acid-induced seizures than wild-type mice at 4 weeks of age. Little is known, however, about how the N-terminal and ankyrin repeat domains (NT-Ank) of Shank3a/b regulate multiple molecular signals in the developing brain. To explore the functional roles of Shank3a/b, we performed a mass spectrometry-based proteomic search for proteins interacting with GFP-tagged NT-Ank. In this study, NT-Ank was predicted to form a variety of complexes with a total of 348 proteins, in which RNA-binding (n = 102), spliceosome (n = 22), and ribosome-associated molecules (n = 9) were significantly enriched. Among them, an X-linked intellectual disability-associated protein, Nono, was identified as a NT-Ank-binding protein. Coimmunoprecipitation assays validated the interaction of Shank3 with Nono in the mouse brain. In agreement with these data, the thalamus of Shank3a/b-knockout mice aberrantly expressed splicing isoforms of autism-associated genes, Nrxn1 and Eif4G1, before and after seizures with kainic acid treatment. These data indicate that Shank3 interacts with multiple RNA-binding proteins in the postnatal brain, thereby regulating the homeostatic expression of splicing isoforms for autism-associated genes after birth.

ATP1A3 regulates protein synthesis for mitochondrial stability under heat stress.

Pathogenic variants in ATP1A3, the gene encoding the α3 subunit of the Na+/K+-ATPase, cause alternating hemiplegia of childhood (AHC) and related disorders. Impairments in Na+/K+-ATPase activity are associated with the clinical phenotype. However, it remains unclear whether additional mechanisms are involved in the exaggerated symptoms under stressed conditions in patients with AHC. We herein report that the intracellular loop (ICL) of ATP1A3 interacted with RNA-binding proteins, such as Eif4g (encoded by Eif4g1), Pabpc1 and Fmrp (encoded by Fmr1), in mouse Neuro2a cells. Both the siRNA-mediated depletion of Atp1a3 and ectopic expression of the p.R756C variant of human ATP1A3-ICL in Neuro2a cells resulted in excessive phosphorylation of ribosomal protein S6 (encoded by Rps6) and increased susceptibility to heat stress. In agreement with these findings, induced pluripotent stem cells (iPSCs) from a patient with the p.R756C variant were more vulnerable to heat stress than control iPSCs. Neurons established from the patient-derived iPSCs showed lower calcium influxes in responses to stimulation with ATP than those in control iPSCs. These data indicate that inefficient protein synthesis contributes to the progressive and deteriorating phenotypes in patients with the p.R756C variant among a variety of ATP1A3-related disorders.

Heterogeneity and mitochondrial vulnerability configurate the divergent immunoreactivity of human induced microglia-like cells.

Microglia play versatile roles in progression of and protection against neuroinflammatory diseases. Little is known, however, about the mechanisms underlying the diverse reactivity of microglia to inflammatory conditions. We investigated how human induced microglia-like (iMG) cells respond to innate immune ligands. Quantitative PCR showed that poly-I:C and lipopolysaccharide (LPS) activated the expression of IL1B and TNF. Immunoreactivity of iMG did not differ between controls (n = 11) and patients with neuroinflammatory diseases (n = 24). Flow cytometry revealed that CD14high cells expressed interleukin (IL) -1ß after LPS treatment. Immunoblotting showed that poly-I:C and LPS differentially activated inflammatory pathways but commonly induced mitochondrial instability and the expression of pyruvate kinase isoform M2 (PKM2). Furthermore, a potent stimulator of PKM2 (DASA-58) alleviated IL-1ß production after LPS treatment. These data indicate that heterogeneous cell populations and mitochondrial stability underlie the divergent immunoreactivity of human iMG in environments.

Shank3a/b isoforms regulate the susceptibility to seizures and thalamocortical development in the early postnatal period of mice.

Epileptic seizures are distinct but frequent comorbidities in children with autism spectrum disorder (ASD). The hyperexcitability of cortical and subcortical neurons appears to be involved in both phenotypes. However, little information is available concerning which genes are involved and how they regulate the excitability of the thalamocortical network. In this study, we investigate whether an ASD-associated gene, SH3 and multiple ankyrin repeat domains 3 (Shank3), plays a unique role in the postnatal development of thalamocortical neurons. We herein report that Shank3a/b, the splicing isoforms of mouse Shank3, were uniquely expressed in the thalamic nuclei, peaking from two to four weeks after birth. Shank3a/b-knockout mice showed lower parvalbumin signals in the thalamic nuclei. Consistently, Shank3a/b-knockout mice were more susceptible to generalized seizures than wild-type mice after kainic acid treatments. Together, these data indicate that NT-Ank domain of Shank3a/b regulates molecular pathways that protect thalamocortical neurons from hyperexcitability during the early postnatal period of mice.

Neurodevelopmental Outcomes of High-Risk Preterm Infants: A Prospective Study in Japan.

OBJECTIVES: To determine the neurodevelopmental outcomes of very-low-birth-weight infants (VLBWIs, birth weight <1,500 g) after 9 years of follow-up. METHODS: This study prospectively recruited 224 VLBWIs born from 2003 to 2009 in Kyushu University Hospital, Japan. Comorbidities of neurocognitive impairment, epilepsy, and autism spectrum disorder or attention-deficit hyperactivity disorder (ASD/ADHD) were assessed at age 3, 6, and 9 years. RESULTS: Neurodevelopmental profiles were obtained from 185 (83%), 150 (67%), and 119 (53%) participants at age 3, 6, and 9 years, respectively. At age 9 years, 25 (21%) VLBWIs showed intelligence quotient (IQ) <70, 11 (9%) developed epilepsy, and 14 (12%) had a diagnosis of ASD/ADHD. The prevalence of epilepsy was higher in children with an IQ <70 at age 9 years than in those with an IQ ≥70 (44% vs 0%). In contrast, ASD/ADHD appeared at similar frequencies in children with an IQ <70 (16%) and ≥70 (11%). Perinatal complications and severe brain lesions on MRI were considered common perinatal risks for developmental delay and epilepsy but not for ASD/ADHD. Male sex was identified as a unique risk factor for ASD/ADHD. CONCLUSION: These data suggest that VLBWIs showed a higher prevalence of developmental delay, epilepsy, and ASD/ADHD at age 9 years than the general population. Distinct mechanisms might be involved in the pathogenic process of ASD/ADHD from those of developmental delay and epilepsy.

Paroxysmal sympathetic hyperactivity and the later development of epilepsy in a chemotherapy-associated brain damage.

BACKGROUND: Chemotherapy in childhood leukemia potentially induces brain lesions and neurological sequelae. Paroxysmal sympathetic hyperactivity (PSH) is known as a treatment-associated complication; however, the full clinical spectra of PSH remain to be elusive. CASE REPORT: A 5-year-old girl was diagnosed of acute myeloid leukemia (AML) M5. After the intensification therapy, she developed recurrent symptoms of episodic tachycardia, hypertension and perspiration lasting for several hours per day. The low-frequency-high-frequency ratio on Holter electrocardiography was rapidly increased from 0.84 to 2.24 at the onset of the paroxysmal event, whereas the video-monitoring electroencephalography (EEG) never identified ictal patterns of epileptiform discharges during the episodes. Thus, the diagnosis of PSH was given at 7 years of age. Myoclonic and generalized tonic-clonic seizures frequently appeared from 10 years of age, which poorly responded to anticonvulsants. EEG showed diffuse slow-wave bursts with multifocal spikes. Serial head magnetic resonance imaging (MRI) revealed diffuse cerebral and hippocampal atrophy, but not inflammatory lesions in the limbic system. CONCLUSION: We first demonstrate a pediatric case with PSH who developed drug-resistant epilepsy 3 years after the onset of PSH. Our data suggest the pathophysiological link of persistent PSH with chemotherapy-associated brain damage.

Favorable outcomes of interferon-α and ribavirin treatment for a male with subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a slow virus infection associated with mutant measles virus (MeV). The long-term outcome of antiviral treatments remains to be determined. We herein present a Japanese boy who was diagnosed with SSPE at 10 years of age. Intraventricular infusions of interferon-α effectively prevented the progress of symptoms during 14 years of follow-up period. Flow-cytometric analysis demonstrated higher proportion of T helper 17 cells (Th17, 18.2%) than healthy controls (4.8-14.5%) despite the normal subpopulation of peripheral lymphocytes. These data suggest that a group of patients with SSPE may show favorable responses to intraventricular infusions of interferon-α.

Management of apnea in infants with trisomy 18.

This case series aimed to characterize the clinical features, management, and outcomes of apnea in infants with trisomy 18. Participants in this study were infants with trisomy 18 who were born alive and admitted to the neonatal intensive care unit in Kyushu University Hospital from 2000 to 2018. Retrospective analysis was performed on clinical data recorded in our department. Twenty-seven infants with trisomy 18 were admitted to our hospital during the study period, of which 25 (nine males, 16 females) were enrolled as eligible participants in this study. Among them, 14 started presenting with apnea from median 3.5 days of age (range 0-47d). In these infants with apnea, eight received respiratory support of positive pressure ventilation (PPV). The 1-year survival rate of infants in the PPV group was higher than that of non-PPV-supported infants (5 out of 8 vs 0 out of 6 infants). Five PPV-supported infants received a diagnosis of epilepsy, which was controlled by antiepileptic drugs. Postnatal respiratory intervention provides better prognosis in infants with trisomy 18. Improved survival leads to accurate diagnosis and treatment of apneic events in association with epilepsy. WHAT THIS PAPER ADDS: Respiratory support is effective against apnea in infants with trisomy 18. Intervention with ventilation provides a higher chance of prolonged survival. Improved survival leads to the accurate diagnosis and treatment of epilepsy-associated apnea.