Effect of neuregulin-1 on cardiac glucose metabolism in rats with experimental myocardial infarction / 中华心血管病杂志

Objective: To investigate the effect of neuregulin-1(NRG-1) on cardiac glucose metabolism in Sprague Dawley (SD) rats with experimental myocardial infarction (MI). Methods: Adult male SD rats were randomly divided into three groups: the sham-operated group, MI group, and MI+NRG1 group. The rat MI model was established via ligation of the left anterior descending coronary artery. Two weeks after operation, echocardiography was performed, MI rats with left ventricular ejection fraction (LVEF) between 0.3-0.5 were selected and randomly assigned to MI group and MI+NRG-1 group. Rats in MI+NRG-1 group were treated with recombinant human NRG-1β (100 μg/kg) via tail vein at 2 weeks after operation (twice per week for 6 weeks); while rats in sham-operated group and MI group received equal volume of physiological saline. By the end of administration, echocardiography and small animal positron emission tomography (PET) were performed to detect cardiac function and myocardial glucose uptake. Myocardial morphology and collagen volume fraction, cardiomyocyte apoptosis and reactive oxygen species (ROS) production were evaluated by histopathologic analysis. Myocardial pyruvate dehydrogenase (PDH) and citrate synthase (CS) activity, as well as ATP production were detected by commercial kits. The mRNA and protein expression levels of NRG-1, p-ErbB4, and key factors involved in glucose metabolism (including Glut-4, HK2, PDK4, PDH, CS) were detected by quantitative real-time PCR (qRT-PCR) and Western blot assay, respectively. Results: With the MI model successfully established, the left ventricular ejection fraction(LVEF) and left ventricular shortening fraction(LVFS) were significantly lower in MI group and MI+NRG-1 group than that in sham group (both P<0.01), while there was no significant difference between MI group and MI+NRG-1 group(all P>0.05). After 6 weeks of NRG-1β intervention, the LVEF and LVFS were significantly higher in MI+NRG-1 group than in MI group (both P<0.01). By the end of experiment, PET imaging showed that the mean standardized uptake value (SUVmean) were lower in MI+NRG-1 group than in the sham group (4.06±0.28 vs. 5.18±0.37, P<0.01), while significantly higher than that in MI group (4.06±0.28 vs.2.86±0.49, P<0.01). Histopathological analysis showed that compared with MI group, rats in MI+NRG-1 group exhibited significantly decreased left ventricle collagen volume fraction ((7.83±1.24) % vs. (18.31±3.58) %, P<0.01), cardiomyocyte apoptosis((37.98±4.26)% vs. (67.04±5.38)%, P<0.01), and DHE fluorescence intensity(0.057 28±0.007 06 vs. 0.076 94±0.008 46, P<0.01), indicating that NRG-1β could reduce ROS production. PDH activity, CS activity, and ATP production were significantly higher in MI+NRG-1 group than in MI group (all P<0.05). qRT-PCR demonstrated an upregulated Glut-4, HK2 and CS, but downregulated PDK4 mRNA expression in MI+NRG-1 group compared with MI group (all P<0.01). Western blot assay showed significantly higher protein expression of NRG-1, p-ErbB4, Glut-4, HK2, PDH, CS in MI+NRG-1 group than in MI group (all P<0.01). Conclusion: NRG-1 could improve glucose uptake and utilization in myocardium by activating phosphorylation of myocardial ErbB4 receptor in MI rats, thus providing a therapeutic option for improving energy metabolism after MI.

Neuregulin 1/ErbB4 signaling attenuates neuronal cell damage under oxygen-glucose deprivation in primary hippocampal neurons / 대한해부학회지

Genome-Wide Association Studies of Autoimmune Thyroid Diseases, Thyroid Function, and Thyroid Cancer

Thyroid diseases, including autoimmune thyroid diseases and thyroid cancer, are known to have high heritability. Family and twin studies have indicated that genetics plays a major role in the development of thyroid diseases. Thyroid function, represented by thyroid stimulating hormone (TSH) and free thyroxine (T4), is also known to be partly genetically determined. Before the era of genome-wide association studies (GWAS), the ability to identify genes responsible for susceptibility to thyroid disease was limited. Over the past decade, GWAS have been used to identify genes involved in many complex diseases, including various phenotypes of the thyroid gland. In GWAS of autoimmune thyroid diseases, many susceptibility loci associated with autoimmunity (human leukocyte antigen [HLA], protein tyrosine phosphatase, non-receptor type 22 [PTPN22], cytotoxic T-lymphocyte associated protein 4 [CTLA4], and interleukin 2 receptor subunit alpha [IL2RA]) or thyroid-specific genes (thyroid stimulating hormone receptor [TSHR] and forkhead box E1 [FOXE1]) have been identified. Regarding thyroid function, many susceptibility loci for levels of TSH and free T4 have been identified through genome-wide analyses. In GWAS of differentiated thyroid cancer, associations at FOXE1, MAP3K12 binding inhibitory protein 1 (MBIP)-NK2 homeobox 1 (NKX2-1), disrupted in renal carcinoma 3 (DIRC3), neuregulin 1 (NRG1), and pecanex-like 2 (PCNXL2) have been commonly identified in people of European and Korean ancestry, and many other susceptibility loci have been found in specific populations. Through GWAS of various thyroid-related phenotypes, many susceptibility loci have been found, providing insights into the pathogenesis of thyroid diseases and disease co-clustering within families and individuals.

Exogenous neuregulin-1 attenuates STZ-induced diabetic peripheral neuropathic pain in rats

Abstract Purpose: To investigate whether modulating NRG1 could attenuate diabetic neuropathic pain and analyze the underlying mechanism. Methods: Male SD rats were randomly divided into control group, diabetic group, NRG1 intervention group. After STZ-induced 2 weeks, NRG1 intervention daily for consecutive 7 days. 4 weeks after NRG1 intervention, both the mechanical withdrawal threshold and the morphological changes of the dorsal root ganglion and sural nerve were observed. Meanwhile, the expression of NGF, IL-1β, TNF-α in spinal cord were determined. Results: Compared with the diabetic group, NRG1 treatment improved the mechanical withdrawal threshold in diabetic rats, pathological changes of dorsal root ganglion and sural nerve were alleviated by NRG1 treatment with electron microscopy imagine. Moreover, compared with the control group, the expression of NGF was significantly decreased and the production of IL-1β, TNF-α were markedly induced in diabetic group. Furthermore, NRG1 treatment could normalized the above effect as compared to diabetic group. Conclusion: NRG1 exerted positive effects on the behavioral and pathological changes of rats with STZ-induced diabetic neuropathic pain, the underlying mechanism might be related to the promotion of NGF excretion and the inhibition of inflammatory cytokines excretion.

The Scaffolding Protein, Grb2-associated Binder-1, in Skeletal Muscles and Terminal Schwann Cells Regulates Postnatal Neuromuscular Synapse Maturation

The vertebrate neuromuscular junction (NMJ) is considered as a “tripartite synapse” consisting of a motor axon terminal, a muscle endplate, and terminal Schwann cells that envelope the motor axon terminal. The neuregulin 1 (NRG1)-ErbB2 signaling pathway plays an important role in the development of the NMJ. We previously showed that Grb2-associated binder 1 (Gab1), a scaffolding mediator of receptor tyrosine kinase signaling, is required for NRG1-induced peripheral nerve myelination. Here, we determined the role of Gab1 in the development of the NMJ using muscle-specific conditional Gab1 knockout mice. The mutant mice showed delayed postnatal maturation of the NMJ. Furthermore, the selective loss of the gab1 gene in terminal Schwann cells produced delayed synaptic elimination with abnormal morphology of the motor endplate, suggesting that Gab1 in both muscles and terminal Schwann cells is required for proper NMJ development. Gab1 in terminal Schwann cells appeared to regulate the number and process elongation of terminal Schwann cells during synaptic elimination. However, Gab2 knockout mice did not show any defects in the development of the NMJ. Considering the role of Gab1 in postnatal peripheral nerve myelination, our findings suggest that Gab1 is a pleiotropic and important component of NRG1 signals during postnatal development of the peripheral neuromuscular system.

Impact of Cell Density on Differentiation Efficiency of Rat Adipose-derived Stem Cells into Schwann-like Cells

BACKGROUND AND OBJECTIVES: Schwann-like (SC-like) cells induced from adipose-derived stem cells (ASCs) may be one of the ideal alternative cell sources for obtaining Schwann cells (SCs). They can be used for treating peripheral nerve injuries. Co-culture with SCs or exposure to glial growth factors are commonly used for differentiation of ASCs to SC-like cells. However, the effect of initial cell density as an inductive factor on the differentiation potential of ASCs into the SC-like cells has not been yet investigated. METHODS AND RESULTS: ASCs were harvested from rat and characterized. The cells were seeded into the culture flasks at three different initial cell densities i.e. 2×10³, 4×10³ and 8×10³ cells/cm² an overnight and differentiated toward SC-like cells using glial growth factors. After two weeks, the differentiation rate of ASCs to SC-like cells at different densities was assessed by immunofluorescence, fluorescence-activated cell sorting analysis and real time RT-PCR. Expression of the typical SCs markers, S-100 proteins and glial fibrillary acidic protein (GFAP) protein, was observed in all cell densities groups although the number of S100-positive and GFAP-positive cells, and the expression of p75(NTR) mRNA, another SC marker, were significantly higher at the density of 8×10³ cells/cm² when compared with the other cell densities groups (p<0.001). CONCLUSIONS: The results suggest that the higher differentiation rate of ASCs to SC-like cells can be obtained at initial cell density of 8×10³ cells/cm², possibly via increased cell-cell interaction and cell density-dependent influence of glial growth factors.

Increased Expression of Neuregulin 1 and erbB2 Tyrosine Kinase in the Bladder of Rats With Cyclophosphamide-Induced Interstitial Cystitis / 대한배뇨장애요실금학회지

PURPOSE: The aim of this study was to evaluate changes in expressions of neuregulin (NRG)1 and erbB2 tyrosine kinase (ErbB2) in bladders of rats with cyclophosphamide (CYP)-induced interstitial cystitis (IC). METHODS: Twenty-four Sprague-Dawley rats were divided into the IC group (n=16) and the control group (n=8). After inducing IC with intraperitoneal CYP injection, expressions of NRG1 and ErbB2 were analyzed using western blotting and reverse transcriptase-polymerase chain reaction. RESULTS: In Western blotting, relative intensities and distributions of both NRG1 and ErbB2 were approximately 1.5- and 3.2-fold higher, respectively, in the IC group than in the control group (mean+/-standard deviation: 1.42+/-0.09 vs. 0.93+/-0.15 and 0.93+/-0.16 vs. 0.29+/-0.08, P<0.05). In the rat bladder samples, mRNA expression levels of NRG1 and ErbB2 were higher in the IC group than in the control group (P<0.05). CONCLUSIONS: Our study has demonstrated significant changes in mRNA expression and immunoreactivity of NRG1 and ErbB2 receptors in the urinary bladder after CYP-induced IC. These results suggest that the up-regulated NRG1 may play a role in inducing an overactive bladder and promoting regeneration in the inflammatory bladder with CYP-induced IC.

Mitogen Activated Protein Kinase Family Proteins and c-jun Signaling in Injury-induced Schwann Cell Plasticity

Schwann cells (SCs) in the peripheral nerves myelinate axons during postnatal development to allow saltatory conduction of nerve impulses. Well-organized structures of myelin sheathes are maintained throughout life unless nerves are insulted. After peripheral nerve injury, unidentified signals from injured nerves drive SC dedifferentiation into an immature state. Dedifferentiated SCs participate in axonal regeneration by producing neurotrophic factors and removing degenerating nerve debris. In this review, we focus on the role of mitogen activated protein kinase family proteins (MAP kinases) in SC dedifferentiation. In addition, we will highlight neuregulin 1 and the transcription factor c-jun as upstream and downstream signals for MAP kinases in SC responses to nerve injury.

Production and evaluation of chicken antibodies against a synthetic peptide from glial growth factor / Producción y evaluación de anticuerpos de gallinas contra un péptido sintético del factor de crecimiento glial

Neuregulins (NRG) are proteins that belong to the family of epidermal growth factors. It is well established that these factors are essential for the development and maintenance of the nervous system. Due to the difficulty of purifying enough quantities of these factors and the lack of specificity from commercially available antibodies, the aim of this work was to produce antibodies against a synthetic peptide capable to detect and identify neuregulin GGFb isoforms. To accomplish this goal, polyclonal antibodies were raised in hens against a synthetic peptide designed from the GGFb1 extracellular sequence. The sequence analysis was made using different epitope-predicting programs. Our results showed that the peptide sequence selected was immunogenic because it was capable of inducing a specific type B immune response in the experimental animal model. These antibodies were also capable of recognizing a recombinant GGF protein and GGF isoforms present in different samples. Our results suggest that the development of immunoglobulin Y (IgY) using synthetic peptides represents, a valuable tool for neuroscience research.

Las Neuregulinas (NRG) son proteínas que pertenecen a la familia de los factores de crecimiento epidermal. Se ha demostrado que estos factores son esenciales para el desarrollo y mantenimiento de la funcionalidad del sistema nervioso. Debido a la dificultad para purificar estas proteínas y la falta de especificidad de los anticuerpos disponibles comercialmente, el objetivo de este trabajo fue producir anticuerpos contra un péptido sintético capaz de detectar e identificar una isoforma de la Neuregulina (GGFb). Para lograr este objetivo, se desarrollaron anticuerpos en gallinas (IgY) contra un péptido sintético diseñado a partir de la secuencia aminoacídica de la región extracelular de GGFb, utilizando programas de predicción de epítopes. Los resultados demuestran que el péptido seleccionado fue immunogénico debido a que estimuló una respuesta inmune específica tipo B en el modelo utilizado. Estos anticuerpos fueron también capaces de reconocer una proteína recombinante e isoformas de GGF presentes en diferentes muestras biológicas. Nuestros resultados demuestran el potencial valor de las inmunoglobulinas Y (IgY) contra péptidos sintéticos como una herramienta de aplicación para la investigación en neurociencia.

Neuregulin-1 attenuates mitochondrial dysfunction in a rat model of heart failure / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Mitochondrial dysfunction plays a pivotal role in the progression of left ventricular (LV) remodeling and heart failure (HF). Recombinant human neuregulin-1 (rhNRG-1) improves cardiac function in models of experimental HF and in clinical trials; however, its impact on mitochondrial function during chronic HF remains largely unknown. The purpose of this study was to investigate whether rhNRG-1 could attenuate the functional and structural changes that occur in cardiac mitochondria in a rat model of HF induced by myocardial infarction.</p><p><b>METHODS</b>Sixty adult rats underwent sham or coronary ligation to induce HF. Four weeks after ligation, 29 animals with LV ejective fraction ≤ 50% were randomized to receive either vehicle or rhNRG-1 (10 µg×kg(-1)×d(-1), I.V.) for 10 days, another 12 sham-operated animals were given no treatment. Echocardiography was used to determine physiological changes. Mitochondrial membrane potential (MMP), respiratory function and tissue adenosine triphosphate (ATP) production were analyzed. Cytochrome c expression and cardiomyocyte apoptosis were determined. Oxidative stress was evaluated by reactive oxygen species production using fluorescence assays and gene expression of glutathione peroxidase measured by real-time quantitative PCR.</p><p><b>RESULTS</b>Compared with sham-operated animals, vehicle treated HF rats exhibited severe LV remodeling and dysfunction, significant mitochondrial dysfunction, increased mitochondrial cytochrome c release, increased myocyte apoptosis and enhanced oxidative stress. Short-term treatment with rhNRG-1 significantly attenuated LV remodeling and cardiac function. Concomitant with this change, mitochondrial dysfunction was significantly attenuated; with ATP production, MMP and respiratory function restored, cytochrome c release and apoptosis inhibited, and oxidative stress reduced.</p><p><b>CONCLUSION</b>The present study demonstrated that rhNRG-1 can significantly improve LV remodeling and cardiac function in the failing heart, this beneficial effect is related to reducing mitochondrial dysfunction, myocyte apoptosis and oxidative stress.</p>

A functional comparison between the HER2high/HER3 and the HER2low/HER3 dimers on heregulin-beta1-induced MMP-1 and MMP-9 expression in breast cancer cells

Overexpression of HER2 correlates with more aggressive tumors and increased resistance to cancer chemotherapy. However, a functional comparison between the HER2high/HER3 and the HER2low/HER3 dimers on tumor metastasis has not been conducted. Herein we examined the regulation mechanism of heregulin-beta1 (HRG)-induced MMP-1 and -9 expression in breast cancer cell lines. Our results showed that the basal levels of MMP-1 and -9 mRNA and protein expression were increased by HRG treatment. In addition, HRG-induced MMP-1 and -9 expression was significantly decreased by MEK1/2 inhibitor, U0126 but not by phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294002. To confirm the role of MEK/ERK pathway on HRG-induced MMP-1 and -9 expression, MCF7 cells were transfected with constitutively active adenoviral-MEK (CA-MEK). The level of MMP-1 and -9 expressions was increased by CA-MEK. MMP-1 and -9 mRNA and protein expressions in response to HRG were higher in HER2 overexpressed cells than in vector alone. The phosphorylation of HER2, HER3, ERK, Akt, and JNK were also significantly increased in HER2 overexpressed MCF7 cells compared with vector alone. HRG-induced MMP-1 and -9 expressions were significantly decreased by lapatinib, which inhibits HER1 and HER2 activity, in both vector alone and HER2 overexpressed MCF7 cells. Finally, HRG-induced MMP-1 and MMP-9 expression was decreased by HER3 siRNA overexpression. Taken together, we suggested that HRG-induced MMP-1 and MMP-9 expression is mediated through HER3 dependent pathway and highly expressed HER2 may be associated with more aggressive metastasis than the low expressed HER2 in breast cancer cells.

Association between a Missense Polymorphism (rs3924999, Arg253Gln) of Neuregulin 1 and Schizophrenia in Korean Population

Neuregulin 1 (NRG1) is associated with the pathogenesis of schizophrenia through controlling activation and signaling of neurotransmitter receptors. Influence to schizophrenia development by the NRG1 gene may differ in individuals, and genetic polymorphism is one of the factors affecting their differences. Association between three single nucleotide polymorphisms (SNPs) (rs7014762, -1174 A/T; rs11998176, -788 A/T; rs3924999, Arg253Gln) of NRG1 and the development of schizophrenia was analyzed in 221 schizophrneia and 359 control subjects. Polymerase chain reaction and direct sequencing were performed to obtain genotype data of NRG1 SNPs of the subjects. In analysis of genetic data, multiple logistic regression models (codominant1, codominant2, dominant, recessive, and log-additive model) were applied. SNPStats and SPSS 18.0 were used to calculate odds ratio (OR), 95% confidence interval (CI), and p-value of each model. The genotype distributions of rs3924999 were associated with schizophrenia development (OR=0.67, 95% CI=0.47-0.95, p=0.022 in the dominant model and OR=0.69, 95% CI=0.51-0.93, p=0.013 in the log-addtive model) and allelic distributions also showed significant association (OR=0.70, 95% CI=0.52-0.93, p=0.014). The results suggest that rs3924999 of the NRG1 gene may be associated with schizophrenia susceptibility.

Endogenous neuregulin-1 expression in the anterior pituitary of female Wistar-Furth rats during the estrous cycle / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the changes in endogenous neuregulin-1 (Nrg1) expression in the anterior pituitary of female Wistar-Furth rats in different phases of the estrous cycle.</p><p><b>METHODS</b>Female Wistar-Furth rats during estrous cycles were used. RT-PCR was employed to study the changes in the expression of Nrg1 isoforms and their cognate receptors ErbB-2 and ErbB-4 in the anterior pituitary in different phases of the estrous cycle. Western blotting was used to detect Nrg1 expression at the protein level. Immunofluorescence staining was used to identify hypophyseal cells expressing Nrg1 and observe the localization and distribution of Nrg1 and functional phosphorylation of ErbB-4. The co-expression of Nrg1 and ErbB-4 in the anterior pituitary of Rhesus monkey was also investigated.</p><p><b>RESULTS</b>Some of the Nrg1 isoforms, especially type III Nrg1s, were expressed at a higher level during the estrous cycle I (E1) and estrous cycle II (E2), a result consistent with that of Western blotting for samples of the anterior pituitaries collected at these phases. Immunofluorescence staining identified the gonadotrophs as the main source of Nrg1, and showed an extensive distribution of Nrg1 in the anterior pituitary in E1 and E2 phases accompanied by apparent phosphorylated activation of ErbB-4. Adjacent distribution of Nrg1- and ErbB-4-positive cells was also observed in the anterior pituitary of male Rhesus monkeys.</p><p><b>CONCLUSION</b>Our results provide evidence for the expression of multiple Nrg1 isoforms and the presence of Nrg1/ErbB-4 signaling in the anterior pituitary of female Wistar-Furth rats. This signaling demonstrates an estrous cycle phase-related pattern. Additionally, Nrg1/ErbB-4-based juxtacrine signaling may exist in the anterior pituitary of male non-human primate.</p>

Neuregulin promotes spermatogonia proliferation in mice / 中华男科学杂志

<p><b>OBJECTIVE</b>To explore the role of neuregulin (neural regulation of protein, NRG) in the process of mouse spermatogonia proliferation.</p><p><b>METHODS</b>Mouse testis fragments were cultured in the medium DMEM containing purified NRG1beta or NRG3 at the concentration of 50, 100 and 200 ng/ml, respectively, followed by BrdU immunohistochemical staining and determination of the proliferation rate of spermatogonia.</p><p><b>RESULTS</b>Compared with the control group, neuregulin significantly promoted the proliferation of spermatogonia (P < 0.05). The proliferation rates of spermatogonia cultured in the medium with 50, 100 and 200 ng/ml of NRG13 were 1.69, 1.55 and 1.86 times, and those with 50, 100 and 200 ng/ml of NRG3 were 1.35, 1.54 and 2.11 times that of the control.</p><p><b>CONCLUSION</b>NRG1beta and NRG3 can promote the proliferation of mouse spermatogonia, and NRG is expected to be applied in the treatment of male infertility.</p>

Expressional changes of neuregulin-1 gene mRNA in peripheral blood from schizophrenia patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the effect of anti-psychotic treatment on the expression of Neuregulin-1 (NRG1) mRNA in the peripheral blood lymphocytes of schizophrenia patients.</p><p><b>METHODS</b>The NRG1 mRNA in peripheral blood lymphocytes was measured using semi-quantitative reverse transcription (RT)-PCR in 80 first-onset schizophrenia patients, 37 sibling controls and 83 non-related controls. The patients were treated with risperdone and quetiapine for 4 weeks. Positive and negative symptom scale (PANSS) was used to evaluate the severity and clinical efficacy.</p><p><b>RESULTS</b>Prior to the treatment, the expression of NRG1 mRNA expression was significantly lower in patients than other two groups (F=73.004, P=0.000). From the second week on, the level of NRG1 mRNA expression in patients became significantly higher than before and gradually increased, whilst no significant difference between sib and non-sib controls. Prior to the treatment, there was significant correlation (r=-0.232, P=0.038) between the level of NRG1 mRNA and PANSS scores. Four weeks after the treatment, a significant correlation between the reduction rate of PANSS and the change of NRG1 mRNA (r=0.27, P=0.016).</p><p><b>CONCLUSION</b>The expression of NRG1 gene mRNA is associated with schizophrenia. Decreased expression of NRG1 may play a role in the development of schizophrenia, which can be improved by anti-psychotic drugs.</p>

Expression of ErbB4 in the neurons of Alzheimer's disease brain and APP/PS1 mice, a model of Alzheimer's disease / 대한해부학회지

Neuregulin-1 (NRG1) plays important roles in the development and plasticity of the brain, and has also been reported to exhibit potent neuroprotective properties. Although ErbB4, a key NRG1 receptor, is expressed in multiple regions in the adult animal brain, little is known about its role in Alzheimer's disease (AD). AD is characterized by progressive impairment of cognition and behavioral disturbance that strongly correlate with degeneration and death of neurons in the cerebral cortex and limbic brain areas, such as the hippocampus and the amygdala. Here, we show that the ErbB4 and phospho-ErbB4 immunoreactivities were higher intensity in the neurons of the CA1-2 transitional field of AD brains as compared to age-matched controls. Also, ErbB4 expression was increased in the neurons of the cortico medial nucleus amygdala, human basal forebrain and superior frontal gyrus of AD brains. In cerebral cortex and hippocampus of amyloid precursor protein/presenilin 1 double transgenic mice, ErbB4 immunoreactivity significantly increased in comparison to age-matched wild type control. These results suggest that up-regulating of ErbB4 immunoreactivity may involve in the progression of pathology of AD.

Prepulse Inhibition of Startle Response: Recent Advances in Human Studies of Psychiatric Disease

Prepulse inhibition (PPI) is considered to be one of the most promising neurophysiological indexes for translational research in psychiatry. Impairment of PPI has been reported in several psychiatric diseases, particularly schizophrenia, where PPI is considered a candidate intermediate phenotype (endophenotype) of the disease. Recent findings from a variety of research areas have provided important evidence regarding PPI impairment. Human brain imaging studies have demonstrated the involvement of the striatum, hippocampus, thalamus and frontal and parietal cortical regions in PPI. In addition, several genetic polymorphisms, including variations in the genes coding for Catechol O-methyltransferase, Neuregulin 1, nuclear factor kappa-B subunit 3 and serotonin-2A receptor were related to PPI; and these findings support PPI as a polygenetic trait that involves several neurotransmitter pathways. Early psychosis studies suggest that PPI disruption is present before the onset of psychosis. Also, discrepancy of PPI impairment between children and adults can be found in other psychiatric diseases, such as autistic spectrum disorders and posttraumatic stress disorder, and comprehensive investigation of startle response might contribute to understand the impairment of the neural circuitry in psychiatric diseases. Finally, recent studies with both Asian and Caucasian subjects indicate that patients with schizophrenia exhibit impaired PPI, and impaired sensorimotor gating might be a global common psychophysiological feature of schizophrenia. In conclusion, studies of PPI have successfully contributed to a better understanding of the fundamental neural mechanisms underlying sensorimotor gating and will certainly be most valuable in devising future approaches that aim to investigate the complex pathogenesis of psychiatric diseases.

Neuregulin-1 preconditioning protects the heart against ischemia/reperfusion injury through a PI3K/Akt-dependent mechanism / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Neuregulin-1 (NRG-1), the ligand of the myocardial ErbB receptor, is a protein mediator with regulatory actions in the heart. This study investigated whether NRG-1 preconditioning has protective effects on myocardial ischemia/reperfusion (I/R) injury and its potential mechanism.</p><p><b>METHODS</b>We worked with an in vivo rat model with induced myocardial ischemia (45 minutes) followed by reperfusion (3 hours). NRG-1 message was detected in the heart using RT-PCR and the protein levels of NRG-1 and ErbB4 were detected by Western blotting analysis. Infarct size was assessed using the staining agent triphenyltetrazolium chloride and cardiac function was continuously monitored. The levels of creatine kinase and lactate dehydrogenase in plasma were analyzed to assess the degree of cardiac injury. The extent of cardiac apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and by Western blotting analysis of cleaved caspase-3. We examined the phosphorylation of Akt in the myocardium and the effect of PI3K/Akt inhibition on NRG-1-induced cardioprotection.</p><p><b>RESULTS</b>Transcription and expression of NRG-1 and phosphorylation of its ErbB4 receptor were significantly upregulated in the I/R hearts. NRG-1 pretreatment reduced the infarct size following cardiac I/R in a concentration-dependent manner with an optimal concentration of 4 µg/kg in vivo. NRG-1 pretreatment with 4 µg/kg, i.v. markedly reduced the plasma creatine kinase and lactate dehydrogenase levels. Pretreatment with NRG-1 also significantly reduced the percentage of TUNEL positive myocytes and the level of cleaved caspase-3 in the I/R hearts. Pretreatment with NRG-1 significantly increased phosphorylation of Akt following I/R. Furthermore, the cardioprotective effect limiting the infarct size that was induced by NRG-1 was abolished by co-administration of the PI3K inhibitor LY294002.</p><p><b>CONCLUSIONS</b>The concentration of NRG-1, a new autacoid, was rapidly upregulated after myocardial I/R. NRG-1 preconditioning has cardioprotective effects against I/R injury through a PI3K/Akt-dependent mechanism in vivo.</p>

Expression of ErbB4 in the apoptotic neurons of Alzheimer's disease brain / 대한해부학회지

Neuregulin-1 (NRG1) signaling participates in the synaptic plasticity, maintenance or regulation of adult brain. Although ErbB4, a key NRG1 receptor, is expressed in multiple regions in the adult animal brain, little is known about its localization in Alzheimer's disease (AD) brains. We previously reported that ErbB4 immunoreactivity showed regional difference in the hippocampus of age-matched control. In the present paper, immunohistochemical characterization of the distribution of ErbB4 receptor in the hippocampus relative to pathology staging were performed in age-matched control (Braak stage 0, n=6) and AD (Braak stage I/V, n=10). Here, we found that ErbB4 immunoreactivity was significantly increased in apoptotic hippocampal pyramidal neurons in the brains of AD patients, compared to those of age-matched control subjects. In AD brains, ErbB4 immunoreactivity was demonstrated to colocalize with the apoptotic signal Bax in apoptotic hippocampal pyramidal neurons. These results suggest that up-regulation of ErbB4 immunoreactivity in apoptotic neuron may involve in the progression of pathology of AD.

Association analysis of neuregulin 1 gene polymorphism with schizophrenia in Chinese Han population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the association of the Neuregulin 1(NRG1) gene polymorphism with schizophrenia by analyzing allele transmission in schizophrenic parent-proband trios.</p><p><b>METHODS</b>Quantitative real-time PCR was used to check the genotypes of four SNPs-rs221533(C/T), rs7820838(C/T), 433E1006(A/G) and rs3924999(C/T), located at the 5o terminus of the Nrg1 gene, in 258 Chinese Han schizophrenic parent-proband trios. The transmission disequilibrium test (TDT) program (Genehunter software 2.0) was used to evaluate the association of the NRG1 gene with schizophrenia.</p><p><b>RESULTS</b>For all the subjects, the genotypes of the 4 SNPs were in Hardy-Weinberg equilibrium. In all the 258 parent-proband trios, there were significant transmission disequilibrium in allelic transmission of C, A, T from rs221533, 433E1006, rs3924999 loci respectively (rs221533: chi-square was 27.45, P was 0.000; 433E1006: chi-square was 56.08, P was 0.000; rs3924999: chi-square was 10.53, P was 0.001). Haplotype was analyzed at frequency exceeding 1%. In three-marker-haplotype, C/C/G and C/C/A (marker order: rs221533, rs7820838, 433E1006) transmitted predominantly(C/C/G: chi-square was 5.26, P was 45.08; C/C/A: chi-square was 0.026, P was 0.000). In four-marker-haplotype (marker order: rs221533, rs7820838, 433E1006, rs3924999), C/C/G/T, C/C/A/C and C/C/A/T showed transmission disequilibrium (C/C/G/T: chi-square was 10.71, P was 0.001; C/C/A/C: chi-square was 8.83, P was 0.006, C/C/A/T: chi-square was 27.00, P was 0.000). In the positive subtype of parent-proband trios, C/T/G/C hapoltype transmission was not observed.</p><p><b>CONCLUSION</b>The NRG1 gene polymorphism is significantly associated with schizophrenia in Chinese Han, especially in the positive subtype of schizophrenia.</p>