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Abstract Autism spectrum disorder (ASD) is linked to ion channel dysfunction, including chloride voltage-gated channel-4 (CLCN4). We generated Clcn4 knockout (KO) mice by deleting exon 5 of chromosome 7 in the C57BL/6 mice. Clcn4 KO exhibited reduced social interaction and increased repetitive behaviors assessed using three-chamber and marble burying tests. Surprisingly, these symptoms were improved by Risperidone treatment, a drug commonly used to treat ASD. RNA sequencing data from mouse neural progenitor cells (mNPCs) showed that the genes regulating trans-synaptic signaling, transmembrane transport, and neuronal projection development were significantly decreased in Clcn4 knockdown (KD) cells compared to wild type (WT). Moreover, Risperidone treatment increased the genes related to the ion transmembrane transport, membrane potential, and neuron projection development in Clcn4 KD. Abnormalities in synaptic plasticity and dendritic spine formation were also observed in Clcn4 KO compared to WT. We observed that phosphorylation of SYNAPSIN, PSD95, ERK and CREB, as well as the expression of CDK5, were reduced in the brains of Clcn4 KO mice. In Clcn4 KO cortical neurons, the phosphorylation of SYNAPSIN and PSD95 expressions also decreased compared to WT, indicating disrupted synaptic function. Additionally, Sholl analysis revealed a reduction in dendritic branching and neuronal projection length in both mouse and human CLCN4 KD neurons. Finally, the decreased phosphorylation of SYNAPSIN and expression of PSD95 along with dendrite abnormalities were restored after Risperidone treatment. These data suggest that dendritic outgrowth and synapse remodeling may serve as endophenotypic targets for drug efficacy in ASD.

The operational efficacy of lane departure warning systems (LDWS) in autonomous vehicles is critically influenced by the retro-reflectivity of road markings, which varies with environmental wear and weather conditions. This study investigated how changes in road marking retro-reflectivity, due to factors such as weather and physical wear, impact the performance of LDWS. The study was conducted at the Yeoncheon SOC Demonstration Research Center, where various weather scenarios, including rainfall and transitions between day and night lighting, were simulated. We applied controlled wear to white, yellow, and blue road markings and measured their retro-reflectivity at multiple stages of degradation. Our methods included rigorous testing of the LDWS’s recognition rates under these diverse environmental conditions. Our results showed that higher retro-reflectivity levels significantly improve the detection capability of LDWS, particularly in adverse weather conditions. Additionally, the study led to the development of a simulation framework for analyzing the cost-effectiveness of road marking maintenance strategies. This framework aims to align maintenance costs with the safety requirements of autonomous vehicles. The findings highlight the need for revising current road marking guidelines to accommodate the advanced sensor-based needs of autonomous driving systems. By enhancing retro-reflectivity standards, the study suggests a path towards optimizing road safety in the age of autonomous vehicles.

Summary: Neuronal activity can be modeled as a nonlinear dynamical system to yield measures of neuronal state and dysfunction. The electrical recordings of stem cell-derived neurons from individuals with autism spectrum disorder (ASD) and controls were analyzed using minimum embedding dimension (MED) analysis to characterize their dynamical complexity. MED analysis revealed a significant reduction in dynamical complexity in ASD neurons during differentiation, which was correlated to bursting and spike interval measures. MED was associated with clinical endpoints, such as nonverbal intelligence, and was correlated with 53 differentially expressed genes, which were overrepresented with ASD risk genes related to neurodevelopment, cell morphology, and cell migration. Spatiotemporal analysis also showed a prenatal temporal enrichment in cortical and deep brain structures. Together, we present dynamical analysis as a paradigm that can be used to distinguish disease-associated cellular electrophysiological and transcriptional signatures, while taking into account patient variability in neuropsychiatric disorders. : Marchetto, Kim, and colleagues describe the application of dynamical analysis to stem cell-derived neuronal recordings from patients with ASD. They find that dynamical complexity is reduced in ASD electrical activity, as measured by minimum embedding dimension (MED). They go on to describe the gene expression, biological pathway, and neurodevelopmental correlates of the MED signature, supporting findings in the literature. Keywords: autism spectrum disorder, multielectrode array, minimum embedding dimension, dynamical complexity, neurodevelopmental disorder models

Abstract Background The association between exposure to secondhand smoke (SHS) during pregnancy and a child’s neurodevelopment has not been established yet. We explored the association between prenatal exposure to SHS and neurodevelopment at 24 months of age considering genetic polymorphism and breastfeeding in 720 mothers and their offspring enrolled in the Korean multicenter birth cohort study (Mothers and Children Environmental Health, MOCEH). Methods We quantified urine cotinine concentrations in mothers once from 12th to 20th gestational weeks and excluded those whose urine cotinine levels exceeded 42.7 ng/ml to represent SHS exposure in early pregnancy. Mental developmental index (MDI) and psychomotor developmental index (PDI) values were measured using the Korean version of the Bayley Scales of Infant Development II (K-BSID-II) at 24 months of age. A general linear model was used to assess the relationship between maternal urinary cotinine level and neurodevelopment. Results MDI scores were inversely associated with cotinine [β = − 2.73; 95% confidence interval (CI): − 5.32 to − 0.15] in children whose mothers had early pregnancy urinary cotinine levels >1.90 ng/ml. No association was evident in children whose mothers had cotinine levels ≤1.90 ng/ml. This negative association was more pronounced in children whose mothers had both Glutathione S-transferases mu 1 (GSTM1) and theta 1 (GSTT1) null type [β = − 5.78; 95% CI: -10.69 to − 0.87], but not in children whose mothers had any present type of GSTM1/GSTT1 [β = − 1.64; 95% CI: -4.79 to 1.52]. The association was no longer significant when children received breast milk exclusively for up to 6 months [β = − 0.24; 95% CI: -4.69 to 4.20] compared to others [β = − 3.75; 95% CI: -7.51 to 0.00]. No significant association was found for PDI. Conclusions Maternal exposure to SHS during pregnancy may result in delayed MDI in early childhood. This effect might be modified by genetic polymorphism and breastfeeding behavior.

Background: The Mothers and Children's Environmental Health study (MOCEH) is a multi-centric prospective birth cohort study investigating effects of various environmental pollutants like heavy metals, endocrine disruptors, air pollutants, nutrition and lifestyle on birth outcomes, growth and development, health and disease of children. In this study, we report all the outcomes from the MOCEH study describing the different environmental pollutants affecting children’s health and disease. Methods: In MOCEH study, 1,751 pregnant women in their first trimester were recruited at 3 centers from 2006 to 2010 in South Korea. The children were followed from birth up to 6 years. Information on health outcomes of children including birth parameters, demographic characteristics, medical and child-rearing history, and nutritional status, were repeatedly obtained through the follow-ups by questionnaires administration, clinical evaluation, and biological specimen collection and measurements. Prenatal and postnatal measurement in biospecimen, i.e., lead, mercury, cadmium, manganese, 1-hydroxypyrene, 2-naphthol, malonadialdehyde, hippuric acid, bisphenol A and phthalate metabolites, and measurement in air samples, i.e., particulate matter, nitrogen dioxide, and total volatile organic compounds were performed. Results: The results show the adverse effect of prenatal exposure to heavy metals like mercury, lead and cadmium on children’s physical, cognitive and neurobehavioral development. Exposure to endocrine disruptors, air pollution, second hand smoke, and mother’s lifestyle during pregnancy affects children’s growth and development. We also identified specific window periods of exposure of pollutants significantly related to children’s health outcomes. Conclusion: The collective results from MOCEH study provide strong scientific evidence that exposures to prenatal and postnatal environmental pollutants have a negative effect on growth and development of children, which will be useful in implementing effective national policy to improve children’s environmental health. Keywords: Birth cohort, Children Environmental health, Environmental pollutants

The ex utero intrapartum treatment (EXIT) procedure was introduced to reduce fetal hypoxic damage while establishing an airway in fetuses with upper and lower airway obstruction. Delivery of the fetal head and shoulders while maintaining the uteroplacental circulation offers time to secure the fetal airway. Here, we report two cases of EXIT procedure for fetal airway obstruction, which were successfully managed with extensive preoperative planning by a professional multidisciplinary team.

Abstract Background & aims Long-chain polyunsaturated fatty acids (LC-PUFAs) are essential for infant neurodevelopment. The nutritional adequacy of dietary LC-PUFAs depends not only on the LC-PUFAs intake but also on the n-6 to n-3 fatty acid ratio (n-6/n-3 PUFAs). This study aimed to identify the association between the maternal dietary n-6/n-3 PUFAs and motor and cognitive development of infants at 6 months of age. Methods We used data from 960 participants in the Mothers and Children's Environmental Health (MOCEH) study, which is a multi-center prospective cohort study. Dietary intake of pregnant women was assessed by a one-day 24-h recall method. Food consumption of infants was estimated based on the volume of breast milk and weaning foods. The duration of each feed was used to estimate the likely volume of milk consumed. Dietary intake of infants at 6 months was also assessed by a 24-h recall method. Cognitive and motor development of infants at 6 months of age was assessed by the Korean Bayley scales of infant development edition II (BSID-II) including the mental developmental index (MDI) and the psychomotor developmental index (PDI). Results Maternal intakes of n-6/n-3 PUFAs and linoleic acid (LA)-to-α-linolenic acid (ALA) ratio (LA/ALA) were 9.7 ± 6.3 and 11.12 ± 6.9, respectively. Multiple regression analysis, after adjusting for covariates, showed that n-6/n-3 PUFAs was negatively associated with both the MDI (β = −0.1674, P = 0.0291) and PDI (β = −0.1947, P = 0.0380) at 6 months of age. These inverse associations were also observed between LA/ALA and both the MDI and PDI (MDI; β = −0.1567; P = 0.0310, PDI; β = −0.1855; P = 0.0367). Multiple logistic regression analysis, with the covariates, showed that infants whose mother’s LA/ALA were ranked in the 2nd, 3rd, and 4th quartile were at approximately twice the risk with more than twice the risk of delayed performance on the PDI compared to the lowest quartile (1st vs. 2nd; OR = 2.965; 95% CI = 1.376 − 6.390, 1st vs. 3rd; OR = 3.047; 95% CI = 1.374 − 6.756 and 1st vs. 4th; OR = 2.551; 95% CI = 1.160 − 5.607). Conclusions Both the maternal dietary n-6/n-3 PUFAs and LA/ALA intake were significantly associated with the mental and psychomotor development of infants at 6 months of age. Thus, maintaining low n-6/n-3 PUFAs and LA/ALA is encouraged for women during pregnancy.

An online survey was conducted in Korea to identify the unmet medical needs of people living with human immunodeficiency virus (HIV) (PLWH). Participants (n = 105) were mostly male (93.3%), aged >40 years (75.2%), and treated for ≥6 years post-diagnosis (61.9%). Most PLWH (71.4%) were very satisfied/satisfied with their HIV management. Areas of concern were quality of life (QoL) and mental health. Characteristics of a long-term therapeutic agent were ‘low risk of resistance’, ‘high long-term viral suppression efficacy’, and ‘high degree of safety’. Pre-consultation QoL and mental health screening would be beneficial for the long-term success of HIV management. [ABSTRACT FROM AUTHOR]

Background: Globally, the coronavirus disease 2019 (COVID-19) pandemic has compromised human immunodeficiency virus (HIV) services. The study aimed to assess the impact of COVID-19 on the access and delivery of HIV care in Korea. Materials and Methods: People living with HIV (PLHIV), people at risk of HIV (PAR) and prescribers of HIV care were recruited through a patient advocacy group, online communities for men who have sex with men (MSM) and a HIV care center for a web-based survey between October 22 and November 26, 2020. The survey compared the frequency of hospital/clinic visits, HIV-related testing, access to antiretroviral therapy (ART) or preventive medications, and experience with telehealth services by PLHIV and PAR between the pre-pandemic and pandemic eras. Results: One hundred and twelve PLHIV (mean age: 38.5 ± 10.2 years), 174 PAR (mean age: 33.5 ± 8.0 years) and 9 prescribers participated the survey; ≥97% of the PLHIV and PAR were male. A greater proportion of PAR than PLHIV reported a decrease in the frequency of hospital/clinical visits (59.2% vs. 17.0%) and HIV-related testing (50.6% vs. 6.3%) since COVID-19. Among PAR, not engaging or engaging less in high-risk behaviors was the most frequently cited reason (51.1%) for decreased frequency of HIV-related tests. A substantial proportion of PLHIV (12.5%) and PAR (50.0%) experienced interrupted use of ART and HIV preventive medications, respectively. A substantial proportion of PLHIV (35.7%) and PAR (62.5%) were concerned about the long-term accessibility of HIV care, however, >90% had not used any types of telehealth services during the pandemic. Conclusion: Overall, COVID-19 has negatively impacted the access and delivery of HIV services in Korea, especially HIV-related testing for PAR. Our findings highlight the need to develop strategies to mitigate the interrupted HIV care. [ABSTRACT FROM AUTHOR]

Background: Substance use among Korean adolescents has been increasing, but little is known about the correlates of substance use in this population. Identification of the correlates is required for development of preventive approaches that aim to reduce or eliminate risk. Therefore, we examined the prevalence and correlates of substance use including psychological problems in a nationwide sample of Korean adolescents.Methods: Data from the 2014 Korean Youth Risk Behavior Web-Based Survey, collected from 72,060 adolescents aged 12-18 years (mean age 14.94 ± 1.75 years), were analyzed. Participants' lifetime experiences with substances (alcohol, tobacco, and illicit drugs) were assessed. Participants' perceived stress, depressive mood, and suicidality during the previous 12 months were also investigated.Results: The lifetime prevalence estimates of alcohol, tobacco, and illicit drug use were 43.0, 19.9, and 0.4 % of the participants, respectively. The most commonly used illicit drugs were inhalants. Older age, male gender, non-residence with family, low parental educational level and socio-economic status, and low academic achievement were positively and significantly associated with substance use. Substance (alcohol, tobacco, and illicit drug) use was positively and significantly associated with severe stress, depressive mood, and suicidality during the previous 12 months, with the highest odds ratios obtained from illicit drug use.Conclusions: These results indicate that the use of substances (alcohol, tobacco, and illicit drugs) among Korean adolescents is associated with socially disadvantaged families, psychological problems, and risky behavior. Health education including dependency prevention programs is needed for these high-risk groups. [ABSTRACT FROM AUTHOR]

Background Foulds' Delusions-Symptoms-State Inventory (DSSI) has been purported to be a reliable, systematic categorical measure to assess the patients with schizophrenia according to the degree of illness. However, further cross-validations using other clinical measures and diverse samples from other cultures have not been advanced recently. We aimed to examine the validity of the DSSI hierarchical class model using both Korean non-patient and patient (schizophrenia and depression) groups. Method The hypothesis of inclusive, non-reflexive relationships among the DSSI classes was tested. The power of DSSI to detect presence of symptoms was assessed via cross-validation with other clinical measures, and the differences between the clinical features among the DSSI classes were examined using the Minnesota Multiphasic Personality Inventory (MMPI). Results The high rate of model conformity (91.1%) across the samples and cross-validation with other criterion measures provided further support for the validity of DSSI. Conclusions DSSI is a reliable self-report measure that can be applied to both patient and non-patients to assess the presence and severity of psychiatric illness. Future studies that include more diverse clinical groups are necessary to lend further support for its utility in clinical practice. [ABSTRACT FROM AUTHOR]

Objectives The purpose of this study was to investigate clinical profile, efficacy, and safety of long-term treatment with selective serotonin reuptake inhibitors (SSRIs) in Korean autism spectrum disorders (ASDs) patients. Methods Effectiveness was assessed through a retrospective review of self-reported target symptom improvement at the last follow-up visit. Changes in illness severity and improvement were measured using the Clinical Global Impression-Severity (CGI-S) of illness and Clinical Global Impression-Improvement (CGI-I) Scales. Tolerability was assessed through a review of the reason for discontinuation of SSRI and documented adverse events. Results A total of 21 ASDs patients (aged 9 to 19 years) treated with SSRI during July 2010 to July 2011 in department of child and adolescent psychiatry of Seoul National Hospital were identified. The mean duration of SSRI treatment was 47.9 (standard deviation = 36.9) months (range 0.7-114.5), and the mean fluoxetine equivalent dosage of SSRIs was 27.1 ± 10.8 mg. Nineteen (90.5%) patients were using concomitant medication. We found that SSRIs were prescribed for symptoms of agitation, stereotyped behavior, aggression, depression, impulsivity and self-injury in ASDs. Ten patients (47.6%) reported improvement in their target symptom after SSRI treatment based on CGI-I scores (CGI-I ⩽ 2). The side effects were reported in 5 patients (23.8%) ; vomiting (n = 2, 9.5%), excessive mood elevation (n = 1, 4.8%), insomnia (n = 1, 4.8%), somnolence (n = 1, 4.8%) and decreased appetite (n = 1, 4.8%). Self-injurious behavior was reported in one patient (4.8%). Conclusions The results of this study suggest that SSRIs may be used effectively in children and adolescents diagnosed with ASDs. However, safety issues need to be considered carefully when choosing SSRIs for treatment. Future controlled trials are needed to confirm these findings. [ABSTRACT FROM AUTHOR]

This study examined the role of calcineurin, a major calcium-dependent protein phosphatase, in dephosphorylating Ser-9 and activating glycogen synthase kinase-3β (GSK-3β). Treatment with calcineurin inhibitors increased phosphorylation of GSK-3β at Ser-9 in SH-SY5Y human neuroblastoma cells. The over-expression of a constitutively active calcineurin mutant, calcineurin A beta (1–401), led to a significant decrease in phosphorylation at Ser-9, an increase in the activity of GSK-3β, and an increase in the phosphorylation of tau. Km of calcineurin for a GSK-3β phosphopeptide was 469.3 μM, and specific activity of calcineurin was 15.2 nmol/min/mg. In addition, calcineurin and GSK-3β were co-immunoprecipitated in neuron-derived cells and brain tissues, and calcineurin formed a complex only with dephosphorylated GSK-3β. We conclude that in vitro, calcineurin can dephosphorylate GSK-3β at Ser-9 and form a stable complex with GSK-3β, suggesting the possibility that calcineurin regulates the dephosphorylation and activation of GSK-3β in vivo. [ABSTRACT FROM AUTHOR]

Objectives This study evaluated neurocognitive changes after switching from immediate release forms of methylphenidate (MPH-IR) to osmotic release oral system methylphenidate (OROS-MPH). Methods 102 children with attention-deficit/hyperactivity disorder (ADHD) participated in an open label, 28 day trial, performing neurocognitive test at baseline and at 28 days after the switch from MPH-IR to OROS-MPH. Results There were significant improvements in the commission error and the reaction time of both visual and auditory continuous performance tests (CPTs) at 28 days after switching from MPH-IR to OROS-MPH. A positive correlation was observed between the improvement in parent/caregiver-rated IOWA Conners total score (Δ IOWA) and the reduction in commission error (r = 0.3, p = 0.001) and reduction in reaction time variability (r = 0.3, p = 0.006) of visual CPT. In a linear regression model, the change in parent/caregiver-rated IOWA Conners scale total scores were significant predictors of change in commission error (β = 0.3, p = 0.005, CI = 0.4–2.3, adjusted R2 = 0.12) and RT variability (β = 0.3, p = 0.004, CI = 0.5–2.4, adjusted R2 = 0.09) of visual CPT. Conclusions These data suggest that MPH-IR may be successfully switched to OROS-MPH treatment with associated improvements in neurocognitive performance. Large-scale controlled trials are needed to replicate these findings. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Objective: Treatment resistance in early onset schizophrenia (EOS) is one of the most challenging problems in child and adolescent psychiatry. We retrospectively examined the therapeutic dosage, clinical response, and side effect profiles of long-term clozapine treatment in Korean children and adolescents with refractory EOS or very early onset schizophrenia (VEOS). Method: 26 refractory patients treated with clozapine for more than 1 year were analyzed. Efficacy was determined by comparing hospitalization rate and duration, before and after clozapine treatment. Tolerability was assessed through review of documented adverse events. Results: A significant reduction in hospital days per year was observed in 25 (96.2%) patients after clozapine treatment compared to before clozapine. Long-term benefit of the treatment was supported by a further reduction of the hospitalization rate in 14 patients treated with clozapine for more than 3 years. Neutropenia developed in 26.9% patients at 1 year and there was no agranulocytosis. Overall, eight male patients (8/12, 66.7%) and one female patient (1/14, 7%) developed neutropenia and out of the nine patients, seven patients were maintained and two patients were successfully rechallenged on clozapine. Conclusion: These findings suggest that long-term clozapine treatment may effectively reduce the amount of time Asian patients with refractory EOS or VEOS spend in the hospital. However careful monitoring of adverse events is required. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Repeated administrations of NMDA receptor antagonists induce behavioural changes which resemble the symptoms of schizophrenia in animals. ERK and GSK-3β associated signalling pathways have been implicated in the pathogenesis of psychosis and in the action mechanisms of various psychotropic agents. Here, we observed the phosphorylations of ERK and GSK-3β and related molecules in the rat frontal cortex after repeated intraperitoneal injections of MK-801, over periods of 1, 5, and 10 d. Repeated treatment with 0.5, 1, and 2 mg/kg MK-801 increased the phosphorylation levels of the MEK-ERK-p90RSK and Akt-GSK-3β pathways and concomitantly and significantly increased CREB phosphorylation in the rat frontal cortex. However, single MK-801 treatment did not induce these significant changes. In addition, the immunoreactivities of HSP72, Bax, and PARP were not altered, which suggests that neuronal damage may not occur in the rat frontal cortex in response to chronic MK-801 treatment. These findings suggest that chronic exposure to MK-801 may induce pro-survival and anti-apoptotic activity without significant neuronal damage in the rat frontal cortex. Moreover, this adaptive change might be associated with the psychotomimetic action of MK-801. [ABSTRACT FROM AUTHOR]

Heterotrimeric stimulatory GTP-binding protein (Gs) stimulates adenylate cyclases to activate the cAMP signaling pathway. Although the cAMP pathway has been reported to be involved in apoptosis, the role of the Gs-cAMP signaling pathway during reactive oxygen species (ROS)-mediated apoptosis, which is involved in the resistance of cancer cells to chemotherapy and radiation, is not clearly understood. Thus, in this study we aimed to investigate the role of the α subunit of Gs(Gαs) in the ROS-induced apoptosis of cancer cells. The stable expression of constitutively active Gαs(αsQL) inhibited the hydrogen peroxide-induced apoptosis of SH-SY5Y human neuroblastoma cells and reduced the hydrogen peroxide-induced increase in Bak and the decrease in Bcl-xL protein expression. Exogenous Bak expression abolished these inhibitory effects of GαsQL, but Bak small interfering RNA decreased hydrogen peroxide-induced apoptosis. Gαs repressed hydrogen peroxide-induced Bak expression by inhibiting the transcription of Bak mRNA, which resulted from the inhibition of the hydrogen peroxide-induced activation of transcription factors such as AP1, NF-κB, and NFAT. Moreover, Gαs also inhibited the hydrogen peroxide-induced binding of AP1, NF-κB, and NFAT to the Bak promoter. Furthermore, hydrogen peroxide-induced apoptosis was reduced by treating cells with prostaglandin E2, which activates Gαs, but this was augmented by CCPA, which activates Gαs causing a decrease in cAMP levels. From the results, we conclude that Gαs protects neuroblastoma cells from hydrogen peroxide-induced apoptosis by repressing Bak induction, which is mediated by the inhibition of the hydrogen peroxide-induced activations of AP1, NF-κB, and NFAT through cAMP-PKA-CREB signaling system. [ABSTRACT FROM AUTHOR]

Changes in plasma membrane electrical potential evoke signals that regulate the expressions of various genes in the nervous system. However, the role of glycogen synthase kinase 3β (GSK-3β) in this process has not been elucidated. Thus, this study was performed to examine whether membrane depolarization can regulate the phosphorylation of GSK-3β and to identify the molecular mechanisms involved in this regulation. The depolarization by treating with 100 mM KCl for 5 min resulted in the undulating phosphorylation of GSK-3β at Set-9 in SH-SY5Y human neuroblastoma cells, in H19-7/ IGF-IR rat embryonic hippocampal cells, and in PC12 rat pheochromocytoma cells, but not in A172 human glioblastoma cells. Cellular β-catenin contents showed a temporal pattern similar to that of the Ser-9 phosphorylation of GSK-3β. Treatment with wortmannin or calphostin C or the expression of dominant negative Akt inhibited phosphorylation of GSK-3β at Ser-9 following the KCl-induced depolarization of SH-SY5Y cells. Moreover, pretreatment with okadaic acid or cyclosporin A blocked the dephosphorylation of GSK-3β at Ser-9 at 0, 15, and 30 min after KCl-induced depolarization, and the activity of protein phosphatases (PP) 2A and 2B increased at these times. Treatment with nifedipine or calcium-free medium inhibited GSK-3β dephosphorylation following membrane depolarization, and the amounts of co-immunoprecipitated GSK-3β and PP2A changed in parallel with GSK-3β dephosphorylation. Our study demonstrated that KCl-induced depolarization caused undulating GSK-3β phosphorylation/dephosphorylation, which was regulated for the most part by phosphatidylinositol 3-kinase and Akt (phosphorylation) and PP2A and PP2B (dephosphorylation), respectively. [ABSTRACT FROM AUTHOR]

UV radiation induces various cellular responses by regulating the activity of many UV-responsive enzymes, including MAPKs. The βγ subunit of the heterotrimeric GTP-binding protein (Gβγ) was found to mediate UV-induced p38 activation via epidermal growth factor receptor (EGFR). However, it is not known how Gβγ mediates the UVB-induced activation of EGFR, and thus we undertook this study to elucidate the mechanism. Treatment of HaCaT-immortalized human keratinocytes with conditioned medium obtained from UVB-irradiated cells induced the phosphorylations of EGFR, p38, and ERK but not that of JNK. Blockade of heparin-binding EGF-like growth factor (HB-EGF) by neutralizing antibody or CRM197 toxin inhibited the UVB-induced activations of EGFR, p38, and ERK in normal human epidermal keratinocytes and in HaCaT cells. Treatment with HB-EGF also activated EGFR, p38, and ERK. UVB radiation stimulated the processing of pro-HB-EGF and increased the secretion of soluble HB-EGF in medium, which was quantified by immunoblotting and protein staining. In addition, treatment with CRM179 toxin blocked UV-induced apoptosis, but HB-EGF augmented this apoptosis. Moreover, UVB-induced apoptosis was reduced by inhibiting EGFR or p38. The overexpression of Gβ1γ2 increased EGFR-activating activity and soluble HB-EGF content in conditioned medium, but the sequestration of Gβγ by the carboxyl terminus of G protein-coupled receptor kinase 2 (GRK2ct) produced the opposite effect. The activation of Src increased UVB-induced, Gβγ-mediated HB-EGF secretion, but the inhibition of Src blocked that. Overexpression of Gβγ increased UVB-induced apoptosis, and the overexpression of GRK2ct decreased this apoptosis. We conclude that Gβγ mediates UVB-induced human keratinocyte apoptosis by augmenting the ectodomain shedding of HB-EGF, which sequentially activates EGFR and p38. [ABSTRACT FROM AUTHOR]