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Smoking remains the leading cause of preventable death in the United States, with 87% of smokers starting before the age of 18. Age of initiation is a major predictive factor for smoking frequency and successful smoking cessation. People who initiate smoking during adolescences are 2.33 times more likely to become heavy smokers and half as likely to quit compared with smokers who started during adulthood. Additionally, schizophrenia, a disease state linked to altered neurodevelopment during adolescence, is a major predictive factor for smoking status. Smoking rates among people suffering from schizophrenia are between 60% and 90%. Interestingly, the Neuregulin Signalling Pathway (NSP), which plays an important role in neurodevelopment, is implicated in both schizophrenia and nicotine use disorder. Specifically, SNPS in neuregulin 3 (Nrg3) and Erb-B2 Receptor Tyrosine Kinase 4 (ErbB4) have been associated with smoking cessation outcomes and schizophrenia. Here, we examine the effects of chronic nicotine (18 mg/kg/day) and 24-h withdrawal on NSP gene expression in the hippocampus of adult (20-week-old) and adolescent (4-week-old) mice. We show that withdrawal from chronic nicotine decreased the expression of Erbb4 mRNA in the hippocampus of the adult mice but increased the expression of cytosolic Erbb4 protein in adolescent mice. Nrg3 mRNA and protein expression was not altered by chronic nicotine or withdrawal in the adult or adolescent cohorts, but Nrg3 mRNA and synaptosomal protein expression was lower in the adult withdrawal group when compared with their adolescent counterparts. These results highlight the age-specific effects of nicotine withdrawal on the NSP and may contribute to the lower quit rate and higher cigarette consumption of smokers who initiation during adolescences.

Neuregulins (NRGs) and their cognate neuronal receptor ERBB4, which is expressed in GABAergic and dopaminergic neurons, regulate numerous behaviors in rodents and have been identified as schizophrenia at-risk genes. ErbB4 transcripts are alternatively spliced to generate isoforms that either include (Cyt-1) or exclude (Cyt-2) exon 26, which encodes a cytoplasmic domain that imparts ErbB4 receptors the ability to signal via the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway. Although ErbB4 Cyt-1/2 isoforms have been studied in transfected cultured cells, their functions in vivo remain unknown. Here we generated ErbB4-floxed (ErbB4-Cyt1(fl/fl)) mice to investigate the effects of germline (constitutive) and conditional (acute) deletions of the Cyt-1 exon. Overall receptor mRNA levels remain unchanged in germline ErbB4 Cyt-1 knockouts (Cyt-1 KOs), with all transcripts encoding Cyt-2 variants. In contrast to mice lacking all ErbB4 receptor function, GABAergic interneuron migration and number are unaltered in Cyt-1 KOs. However, basal extracellular dopamine (DA) levels in the medial prefrontal cortex are increased in Cyt-1 heterozygotes. Despite these neurochemical changes, Cyt-1 heterozygous and homozygous mice do not manifest behavioral abnormalities previously reported to be altered in ErbB4 null mice. To address the possibility that Cyt-2 variants compensate for lack of Cyt-1 during development, we microinjected an adeno-associated virus expressing Cre-recombinase (AAV-Cre) into the DA-rich ventral tegmental area of adult ErbB4-Cyt1(fl/fl) mice to acutely target exon 26. These conditional Cyt-1 KOs were found to exhibit behavioral abnormalities in the elevated plus maze and startle response, consistent with the idea that late exon 26 ablation may circumvent compensation by Cyt-2 variants. Taken together, our observations indicate that ErbB4 Cyt-1 function in vivo is important for DA balance and behaviors in the adult.

BackgroundThe inflammatory response caused by microglia in the central nervous system plays an important role in Alzheimer's disease. Neuregulin-1 (NRG1) is a member of the neuregulin family and has been demonstrated to have anti-inflammatory properties. The relationship between NRG1, microglia phenotype and neuroinflammation remains unclear.Materials and MethodsBV2 cells were used to examine the mechanism of NRG1 in regulating microglia polarization. Neuronal apoptosis, inflammatory factors TNF-α and iNOS, microglia polarization, ErbB4 and NF-κB p65 expression were assessed.ResultsWe found that exogenous NRG1 treatment or overexpression improved microglial activity and reduced the secretion of the inflammatory factors TNF-α and iNOS in vitro. The expression of Bax in SH-SY5Y neuron cells incubated with medium collected from the NRG1 treatment group decreased. Additionally, our study showed that NRG1 treatment reduced the levels of the M1 microglia markers CD120 and iNOS and increased the levels of the M2 microglia markers CD206 and Arg-1. Furthermore, we observed that NRG1 treatment attenuated Aβ-induced NF-κB activation and promoted the expression of p-ErbB4 and that knockdown of ErbB4 abrogated the effects of NRG1 on NF-κB, Bax levels and M2 microglial polarization. Conclusion NRG1 inhibits the release of inflammatory factors in microglia and regulates the switching of the M1/M2 microglia phenotype, most likely via ErbB4-dependent inhibition of the NF-κB pathway.

ErbB4 is a member of the ErbB receptor tyrosine kinase family. It has both pro- and anti-oncogenic activities in tumors. Vasculogenic mimicry (VM), a phenomenon in which cancer cells form capillary-like structures without endothelial cells, has been recognized to be a cause of malignant phenotypes in some solid tumors. Here, we used an in vitro VM formation assay, and demonstrated that ErbB4 negatively regulated VM formation in human breast cancer cells. By using CRISPR/Cas9-mediated gene knockout, we verified that the depletion of endogenous ErbB4 improved the VM formation capability. Although treatment with neuregulin 1 (NRG1), a ligand of ErbB4, induced the phosphorylation of ErbB4 and promoted VM formation in a dose-dependent manner, it did not induce such activities in kinase-dead K751M ErbB4-overexpressing cells. Moreover, we examined the effect of the missense mutation E872K of ErbB4, which has been reported in multiple tumors, on VM formation, and found that the mutation enhanced the basal phosphorylation level and ErbB4-mediated VM formation in the absence of NRG1 stimulation. Whereas NRG1 stimulated VM formation, excessive activation of ErbB4 induced a negative effect. In E872K ErbB4-overexpressing cells, but not in wild-type ErbB4-overexpressing cells, the number of VM tubes was significantly decreased by low-dose treatment with the ErbB inhibitor afatinib. Taken together, our findings demonstrated the significance of ErbB4-mediated VM formation, and suggested the possibility of ErbB4 mutations as effective targets in breast cancer.

BACKGROUND: While genome-wide association studies (GWAS) have identified germline variants influencing the risk of developing colorectal cancer (CRC), there has been limited examination of the possible role of inherited variation as a determinant of patient outcome. PATIENTS AND METHODS: We performed a GWAS for overall survival (OS) in 1926 patients with advanced CRC from the COIN and COIN-B clinical trials. For single nucleotide polymorphisms (SNPs) showing an association with OS (P < 1.0 × 10(−5)), we conducted sensitivity analyses based on the time from diagnosis to death and sought independent replications in 5675 patients from the Study of Colorectal Cancer in Scotland (SOCCS) and 16,964 patients from the International Survival Analysis in Colorectal cancer Consortium (ISACC). We analysed the Human Protein Atlas to determine if ERBB4 expression was associated with survival in 438 patients with colon adenocarcinomas. RESULTS: The most significant SNP associated with OS was rs79612564 in ERBB4 (hazard ratio [HR] = 1.24, 95% confidence interval [CI] = 1.16–1.32, P = 1.9 × 10(−7)). SNPs at 17 loci had suggestive associations for OS and all had similar effects on the time from diagnosis to death. No lead SNPs were independently replicated in the meta-analysis of all patients from SOCCS and ISACC. However, rs79612564 was significant in stage-IV patients from SOCCS (P = 2.1 × 10(−2)) but not ISACC (P = 0.89) and SOCCS combined with COIN and COIN-B attained genome-wide significance (P = 1.7 × 10(−8)). Patients with high ERBB4 expression in their colon adenocarcinomas had worse survival (HR = 1.50, 95% CI = 1.1–1.9, P = 4.6 × 10(−2)). CONCLUSIONS: Genetic and expression data support a potential role for rs79612564 in the receptor tyrosine kinase ERBB4 as a predictive biomarker of survival.

The human EGF receptor family plays pivotal roles in physiology and cancer, which contains four closely-related members: HER1/EGFR, HER2, HER3 and HER4. Previously, it was found that the mitogen-inducible gene 6 (Mig6) protein is a negative regulator of EGFR and HER2 by using its S1 segment to bind at the kinase dimerization interface. However, it is still unclear whether the S1 segment can also effectively target HER3 and HER4? Here, we performed a systematic investigation to address this issue. The segment can bind to all the four HER kinases with a varying affinity and moderate selectivity; breaking of the segment into shorter hotspot peptides would largely impair the affinity and selectivity, indicating that the full-length sequence is required for the effective binding of S1 to these kinases. The hs2 peptide, which corresponds to the middle hotspot region of S1 segment, can partially retain the affinity to HER kinases, can moderately compete with S1 segment at the dimerization interfaces, and can mimic the biological function of Mig6 protein to suppress HER4+ esophageal cancer at cellular level. In addition, we also analyzed the binding potency of S1 segment and hs2 peptide to the kinase domains of other five widely documented growth factor receptors (GFRs). It was showed that both the S1 and hs2 cannot effectively interact with these receptors. Overall, the Mig6 is suggested as a specific pan-HER inhibitor, which can target and suppress HER family members with a broad selectivity, but exhibits weak or no activity towards other GFRs.

Background Circular RNAs (circRNAs) are increasingly recognized as important regulators in cancer including ovarian cancer (OC). This work focuses on the effects of circ_0000745 on the OC development of and molecules involved. Methods Expression of circ_0000745 in collected OC tissues and the acquired OC cell lines was examined by RT-qPCR. The stability of circ_0000745 in cells was examined by RNase R treatment. The target transcripts interacted with circ_0000745 were predicted using bioinformatic systems. Gain- and loss-of-function studies of circ_0000745, microRNA (miR)-3187-3p and erb-b2 receptor tyrosine kinase 4 (ERBB4) were conducted to determine their functions on proliferation, migration, invasion and stem cell property of OC cells. Results Circ_0000745 and ERBB4 were abundantly expressed while miR-3187-3p was poorly expressed in OC tissues and cells. Circ_0000745 sequestered miR-3187-3p and blocked its repressive effect on ERBB4. Downregulation of circ_0000745 reduced proliferation, aggressiveness, epithelial-mesenchymal transition, and stemness of SK-OV-3 cells, but this reduction was blocked upon miR-3187-3p inhibition or ERBB4 upregulation. By contrast, artificial induction of circ_0000745 upregulation, miR-3187-3p upregulation and ERBB4 downregulation led to inverse trends in ES-2 cells. ERBB4 promoted the phosphorylation of the PI3K/AKT signaling pathway. An RNA binding protein IGF2BP2 was found to circ_0000745 bind to and promote its expression and stability. Conclusion This study demonstrated that circ_0000745 upregulated by IGF2BP2 promotes aggressiveness and stemness of OC cells through a miR-3187-3p/ERBB4/PI3K/AKT axis. Circ_0000745 may serve as a promising target for OC treatment.

As a gamma-aminobutyric acid type A receptor agonist sevoflurane is a common general anesthetic used in anesthesia and affects the neural development in offspring. We hypothesized that sevoflurane could regulate interneurons via the neuregulin-1-epidermal growth factor receptor-4 (NRG1–ErbB4) pathway in the entorhinal cortex (ECT) of the middle pregnancy. Six female rats in middle pregnancy (14.5 days of pregnancy) were randomly and equally divided into sevoflurane (SeV) and control groups. The rats in the SeV group were exposed to 4% sevoflurane for 3 hours. The expression levels of NRG1 and ErbB4, parvalbumin (PV) and glutamic acid decarboxylase (GAD67), and N-methyl-D-aspartate receptor subunit 2A (NR2A) and subunit 2B (NR2B) in offspring were examined through immunohistochemistry. The pyramidal neurons in the ECT were examined via Golgi staining. The levels of NRG1 and ErbB4 were significantly decreased (P < 0.01) and the levels of PV and GAD67 (interneurons) were found to be decreased in the SeV group (P < 0.01). The level of NR2B was found to be increased while the level of NR2A being decreased in the SeV group (P < 0.01). The development of pyramidal neurons was abnormal in the SeV group (P < 0.05). Conclusively, prenatal sevoflurane exposure could lead to the disturbance of the interneurons by activating the NRG1–ErbB4 pathway and subsequently result in abnormal development of pyramidal neurons in middle pregnancy. Prenatal sevoflurane exposure in middle pregnancy could be potentially harmful to the neural development of rat offspring. This study may reveal a novel pathway in the influence mechanism of sevoflurane on rat offspring.

BACKGROUND: ErbB/PI3K signaling is widely recognized as a critical modulator of malignancy and miRNAs have been found to play a crucial role in the regulation of this pathway. OBJECTIVE: This study aimed to identify novel miRNAs related to the ErbBs loci and investigate the functional effects of these miRNAs on ErbB/PI3K signaling in cancer progression. MATERIALS and METHODS: Bioinformatics tools and RNA-seq data were used to discover novel miRNAs in breast and colon cancer cells. Gene expression levels were determined using RT-qPCR. Western blotting and dual-luciferase assays were used to identify the regulatory mechanism between ErbB4-miR1/2 and related genes. The effects of ErbB4-miR1/2 on cell proliferation, viability, ROS production, and migration were assessed by PI-flow cytometry, colony formation, MTT, ROS, scratch, and transwell assays in SKBR3 and SW480 cells. RESULTS: MicroRNA prediction tools, RNA-seq data, RT-qPCR, and sequencing results identified ErbB4-miR1 and ErbB4-miR2 (ErbB4-miR1/2) as novel miRNAs encoded by ErbB4 gene. ErbB4-miR1/2 were downregulated in breast and colon tumor tissues and also in different cancerous cells. RT-qPCR and dual-luciferase assays revealed that ErbB2 and ErbB3 genes are regulated by ErbB4-miR1/2. Consistently, a decrease in the p-AKT/AKT protein ratio verified the suppressive effect of ErbB4-miR1/2 on ErbB/PI3K activity. Furthermore, ErbB4-miR1/2 overexpression suppressed cell proliferation, viability, and migration, and increased ROS production. CONCLUSIONS: ErbB4-miR1/2 are novel tumor suppressor miRNAs which attenuate ErbB/PI3K signaling in breast and colon cancer cells.

EGFR and ErbB4 are the only two members of cancer-regulating ErbB RTKs that maintain the activation of their extracellular ligand-binding domain and intracellular tyrosine kinase domain. EGFR and ErbB4 could form homo and heterodimers upon their activation. Heterodimerization triggers more diverse intracellular pathways compared to homodimerization. Moreover, it is known that N-glycosylation is crucial for the stabilization and activation of EGFR and ErbB4 receptors. Herein, atomistic molecular dynamics were simulated to study the EGFR-ErbB4 heterodimer in the glycosylated and unglycosylated states. It was shown that the EGFR-ErbB4 heterodimer is highly stabilized by glycosylation. The increased stability is most significant at the dimeric interfaces, regulated by packing of three glycans attached to EGFR (Asn337) and ErbB4 (Asn333, Asn523) at the dimeric interface. Finally, it is proposed that heterodimerization is the persistent key player in the EGFR and ErbB4 activation. Thus, targeting the heterodimers in future therapeutic designs could be a promising approach against drug resistance to ErbB-positive cancers.

Neurons use local protein synthesis to support their morphological complexity, which requires independent control across multiple subcellular compartments up to the level of individual synapses. We identify a signaling pathway that regulates the local synthesis of proteins required to form excitatory synapses on parvalbumin-expressing (PV + ) interneurons in the mouse cerebral cortex. This process involves regulation of the TSC subunit 2 (Tsc2) by the Erb-B2 receptor tyrosine kinase 4 (ErbB4), which enables local control of messenger RNA {mRNA} translation in a cell type–specific and synapse type–specific manner. Ribosome-associated mRNA profiling reveals a molecular program of synaptic proteins downstream of ErbB4 signaling required to form excitatory inputs on PV + interneurons. Thus, specific connections use local protein synthesis to control synapse formation in the nervous system.

Specificity in signaling activated by receptor tyrosine kinases is typically attributed to characteristics of their intracellular domains. Here, the authors demonstrate that an extracellular receptor sequence motif controls intracellular signaling as a result of extracellular glycan interactions.The ErbB4 receptor isoforms JM-a and JM-b differ within their extracellular juxtamembrane (eJM) domains. Here, ErbB4 isoforms are used as a model to address the effect of structural variation in the eJM domain of receptor tyrosine kinases (RTK) on downstream signaling. A specific JM-a-like sequence motif is discovered, and its presence or absence (in JM-b-like RTKs) in the eJM domains of several RTKs is demonstrated to dictate selective STAT activation. STAT5a activation by RTKs including the JM-a like motif is shown to involve interaction with oligosaccharides of N-glycosylated cell surface proteins such as beta 1 integrin, whereas STAT5b activation by JM-b is dependent on TYK2. ErbB4 JM-a- and JM-b-like RTKs are shown to associate with specific signaling complexes at different cell surface compartments using analyses of RTK interactomes and super-resolution imaging. These findings provide evidence for a conserved mechanism linking a ubiquitous extracellular motif in RTKs with selective intracellular STAT signaling.

Objective: To investigate the potential role of EGFR, ErbBs receptors and neuregulins in human adipose tissue physiology in obesity. Methods: Gene expression analysis in human subcutaneous (SAT) and visceral (VAT) adipose tissue in three independent cohorts [two cross-sectional (N = 150, N = 87) and one longitudinal (n = 25)], and in vitro gene knockdown and overexpression experiments were performed. Results: While both SAT and VAT ERBB2 and ERBB4 mRNA increased in obesity, SAT EGFR mRNA was negatively correlated with insulin resistance, but did not change in obesity. Of note, both SAT and VAT EGFR mRNA were significantly associated with adipogenesis and increased during human adipocyte differentiation. In vitro experiments revealed that EGFR, but not ERBB2 and ERBB4, gene knockdown in preadipocytes and in fully differentiated human adipocytes resulted in decreased expression of adipogenic-related genes. ERBB2 gene knockdown also reduced gene expression of fatty acid synthase in fully differentiated adipocytes. In addition, neuregulin 2 (NRG2) mRNA was associated with expression of adipogenic genes in human adipose tissue and adipocytes, and its overexpression increased expression of EGFR and relevant adipogenic genes. Conclusions: This study demonstrates the association between adipose tissue ERBB2 and obesity, confirms the relevance of EGFR on human adipogenesis, and suggests a possible adipogenic role of NRG2.

Background microRNAs (miRNAs) are involved in hepatocellular carcinoma (HCC) development and can control gene expression via directly targeting or regulating DNA methylation. This research aims to analyse the mechanism of miR-93-5p on HCC progression. Methods miR-93-5p, Erb-B2 receptor tyrosine kinase 4 (ERBB4) and ten-eleven translocation methyl-cytosine dioxygenases (TET1, TET2 and TET3) abundances were measured via quantitative reverse transcription polymerase chain reaction and Western blotting. The binding interaction was examined by dual-luciferase reporter analysis and chromatin immunoprecipitation. Cell proliferation and apoptosis were assessed via Cell Counting Kit-8, colony formation and flow cytometry. The DNA methylation of ERBB4 was detected via specific polymerase chain reaction. SNU-449 cells were subcutaneously inoculated into the BALB/c nude mice to establish the in vivo model for HCC, and the in vivo function of miR-93-5p was analysed by intratumoral injections of miR-93-5p antogomir. Results miR-93-5p abundance was enhanced and ERBB4 level was reduced in HCC tumour tissues of 62 patients and HCC cell lines, in contrast with that in paired normal tissues of 62 patients and normal cell lines. ERBB4 was targeted by miR-93-5p. miR-93-5p knockdown or ERBB4 overexpression repressed HCC cell proliferation and promoted apoptosis via decreasing cell viability and colony ability and inducing cycle arrest. ERBB4 silence attenuated the influence of miR-93-5p knockdown on cell proliferation and apoptosis. ERBB4 promoter DNA methylation level was enhanced in HCC samples and cell lines, and ERBB4 abundance was increased via TETs (TET1, TET2 and TET3). miR-93-5p targeted TETs to modulate ERBB4 abundance. TETs silence relieved the influence of miR-93-5p knockdown on cell proliferation and apoptosis. miR-93-5p knockdown decreased HCC growth in a xenograft model. Conclusion miR-93-5p knockdown repressed the progression of HCC via increasing ERBB4 and TETs-dependent DNA demethylation.

OBJECTIVE To investigate the immunohistochemical (IHC) expression of the ErbB/HER family in primary vulvar squamous cell carcinoma (VSCC). METHODS We analyzed a series of 125 patients who were surgically treated for VSCC from January 1980 to June 2016. All cases had lymph node (LN) staging and 80 had LN metastasis. A tissue microarray was built for epidermal growth factor receptor (EGFR), HER2, HER3, and HER4 IHC staining. RESULTS In the primary tumor we found positive expressions for EGFR, HER2, HER3, and HER4 in 5%, 0.9%, 0.9%, and 22.8%, respectively. For the LN metastasis, expressions of EGFR and HER4 were positive in 22.2% and 39.1%, respectively. No cases had positive staining for HER2 and HER3 in the LN metastasis. For HER4, positive expression correlated with smaller tumor sizes (P = 0.02). However, positive HER4 was related to adverse prognostic factors such as: histological grade (P = 0.012), presence of lymphovascular space invasion (40.9% vs 16.2%; P = 0.035), and perineural invasion (57.1% vs 16.7%; P = 0.006). Notably, all cases with LN metastasis had positive HER4 in the primary tumor (P

Epidermal growth factor (EGF) receptors (ErbB1-ErbB4) promote cardiac development and growth, although the specific EGF ligands and receptor isoforms involved in growth/repair versus pathology remain undefined. We challenged ventricular cardiomyocytes with EGF-like ligands and observed that selective activation of ErbB4 (the receptor for neuregulin 1 [NRG1]), but not ErbB1 (the receptor for EGF, EGFR), stimulated hypertrophy. This lack of direct ErbB1-mediated hypertrophy occurred despite robust activation of extracellular-regulated kinase 1/2 (ERK) and protein kinase B. Hypertrophic responses to NRG1 were unaffected by the tyrosine kinase inhibitor (AG1478) at concentrations that are selective for ErbB1 over ErbB4. NRG1-induced cardiomyocyte enlargement was suppressed by small interfering RNA (siRNA) knockdown of ErbB4 and ErbB2, whereas ERK phosphorylation was only suppressed by ErbB4 siRNA. Four ErbB4 isoforms exist (JM-a/JM-b and CYT-1/CYT-2), generated by alternative splicing, and their expression declines postnatally and following cardiac hypertrophy. Silencing of all four isoforms in cardiomyocytes, using an ErbB4 siRNA, abrogated NRG1-induced hypertrophic promoter/reporter activity, which was rescued by coexpression of knockdown-resistant versions of the ErbB4 isoforms. Thus, ErbB4 confers cardiomyocyte hypertrophy to NRG1, and all four ErbB4 isoforms possess the capacity to mediate this effect.

The precise control of the nervous system function under the vitality of synapses is extremely critical. Efforts have been taken to explore the underlying cellular and molecular mechanisms for synapse formation. Cell adhesion molecules have been found important for synapse assembly in the brain. Many trans-adhesion complexes have been identified to modulate excitatory synapse formation. However, little is known about the synaptogenic mechanisms for inhibitory synapses. ErbB4 is a receptor tyrosine kinase enriched in interneurons. Here, we showed that overexpressing ErbB4 in HEK293T cells induced gephyrin or GABAAR α1 puncta in co-cultured primary hippocampal neurons. This induction of ErbB4 was independent of its kinase activity. K751M, a kinase-dead mutant of ErbB4, can also induce gephyrin or GABAAR α1 puncta in the co-culture system. We further constructed K751M knock-in mice and found that the homozygous were viable at birth and fertile without changes in gross brain structure. The number of interneurons and inhibitory synapses onto pyramidal neurons (PyNs) were comparable between K751M and wild-type mice but decreased in ErbB4-Null mice. Moreover, ErbB4 can interact in trans with Slitrk3, a transmembrane postsynaptic protein at inhibitory synapses, through the extracellular RLD domain of ErbB4. The deletion of RLD diminished the induction of gephyrin or GABAAR α1 puncta by ErbB4. Finally, disruption of ErbB4–Slitrk3 interaction through neutralization of Slitrk3 by secretable RLD decreased inhibitory synapses onto PyNs and impaired GABAergic transmission. These results identify that ErbB4, as a cell adhesion molecule, promotes inhibitory synapse formation onto PyNs by interacting with Slitrk3 and in a kinase-independent manner, providing an unexpected mechanism of ErbB4 in inhibitory synapse formation.

How the spinal cord transmits heat signals from the periphery to the brain remains unclear. In this issue of Neuron, Wang et al. (2022) identify a population of spinal cord neurons functioning in this pathway.

BackgroundThe epidermal growth factor receptor (EGFR) family belongs to the transmembrane protein receptor of the tyrosine kinase I subfamily and has 4 members: EGFR/ERBB1, ERBB2, ERBB3, and ERBB4. The EGFR family is closely related to the occurrence and development of a variety of cancers.Materials/methodsIn this study, we used multiple online bioinformatics websites, including ONCOMINE, TCGA, CGGA, TIMER, cBioPortal, GeneMANIA and DAVID, to study the expression profiles, prognostic values and immune infiltration correlations of the EGFR family in glioma.ResultsWe found that EGFR and ERBB2 mRNA expression levels were higher in glioblastoma (GBM, WHO IV) than in other grades (WHO grade II & III), while the ERBB3 and ERBB4 mRNA expression levels were the opposite. EGFR and ERBB2 were notably downregulated in IDH mutant gliomas, while ERBB3 and ERBB4 were upregulated, which was associated with a poor prognosis. In addition, correlation analysis between EGFR family expression levels and immune infiltrating levels in glioma showed that EGFR family expression and immune infiltrating levels were significantly correlated. The PPI network of the EGFR family in glioma and enrichment analysis showed that the EGFR family and its interactors mainly participated in the regulation of cell motility, involving integrin receptors and Rho family GTPases.ConclusionsIn summary, the results of this study indicate that the EGFR family members may become potential therapeutic targets and new prognostic markers for glioma.

The neuregulin 1 (NRG1) ErbB4 module is at the core of an “at risk” signaling pathway in schizophrenia. Several human studies suggest hyperstimulation of NRG1-ErbB4 signaling as a plausible pathomechanism; however, little is known about the significance of stage-, brain area-, or neural cell type-specific NRG1-ErbB4 hyperactivity for disease-relevant brain endophenotypes. To address these spatiotemporal aspects, we generated transgenic mice for Cre recombinase-mediated overexpression of cystein-rich domain (CRD) NRG1, the most prominent NRG1 isoform in the brain. A comparison of “brain-wide” vs cell type-specific CRD-NRG1 overexpressing mice revealed that pathogenic CRD-NRG1 signals for ventricular enlargement and neuroinflammation originate outside glutamatergic neurons and suggests a subcortical function of CRD-NRG1 in the control of body weight. Embryonic onset of CRD-NRG1 in glutamatergic cortical networks resulted in reduced inhibitory neurotransmission and locomotor hyperactivity. Our findings identify ventricular enlargement and locomotor hyperactivity, 2 main endophenotypes of schizophrenia, as specific consequences of spatiotemporally distinct expression profiles of hyperactivated CRD-NRG1 signaling.

SummaryInhibitory neurotransmission in amygdala is important for fear learning and memory. However, mechanisms that control the inhibitory activity in amygdala are not well understood. We provide evidence that neuregulin 1 (NRG1) and its receptor ErbB4 tyrosine kinase are critical for maintaining GABAergic activity in amygdala. Neutralizing endogenous NRG1, inhibition, or genetic ablation of ErbB4, which was expressed in a majority of palvalbumin (PV)+ neurons in amygdala, reduced GABAergic transmission and inhibited tone-cued fear conditioning. Specific ablation of ErbB4 in PV+ neurons reduced eIPSC/eEPSC ratios and impaired fear conditioning. Notably, expression of ErbB4 in amygdala was sufficient to diminish synaptic dysfunction and fear conditioning deficits in PV-ErbB4−/− mice. These observations indicated that NRG1 signaling maintains high GABAergic activity in amygdala and, thus, regulates fear memory. Considering that both NRG1 and ErbB4 are susceptibility genes of schizophrenia, our study sheds light on potential pathophysiological mechanisms of this disorder.

Despite the growing recognition of metabolic reprogramming as an important hallmark of cancer in the past few years, the molecular mechanisms underlying metabolic alterations during tumorigenesis remain unclear. In this study, we identified a critical role of Her4 in rewiring cancer metabolism toward tumor-promoting metabolic processes, including increased glycolysis, glutaminolysis, mitochondrial biogenesis, and oxidative phosphorylation, which may in part cooperate to promote tumorigenesis. We found that overexpression of Her4 promoted the stabilization of c-Myc through a CIP2A-mediated increase in c-MycS62 phosphorylation and GSK3β-mediated decrease in c-MycT58 phosphorylation, both of which decreased c-Myc degradation. Furthermore, Her4 was found to increase glucose uptake and tumor growth in an osteosarcoma xenograft model. Overall, these findings provide a better understanding of the involvement of Her4 in tumorigenesis and document its potential role in metabolic reprogramming for the first time. We believe that our study might lead to promising opportunities for targeted metabolic therapy for cancer.

5-Fluorouracil (5-FU) is a widely used chemotherapeutic agent for breast cancer. However, acquired chemoresistance leads to a loss of its efficacy; methods to reverse are urgently needed. Some studies have shown that pyrotinib, an ErbB receptor tyrosine kinase inhibitor, is effective against HER2+ breast cancer. However, whether pyrotinib sensitizes 5-FU-resistant breast cancer cells to 5-FU is unknown. We hypothesized that the combination of pyrotinib and 5-FU would show synergistic antitumor activity, and pyrotinib could reverse 5-FU resistance in HER2+ breast cancer cells in vitro and in vivo. Our data showed that pyrotinib inhibited the growth of 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines. 5-FU remarkably suppressed the growth of SKBR-3 and MAD-MB-453 cells. However, SKBR-3/FU and MAD-MB-453/FU cells showed resistance to 5-FU. A combination of pyrotinib and 5-FU resulted in the synergistic inhibition of the growth of the 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines. Pyrotinib decreased significantly the IC50 values of 5-FU and the thymidylate synthase (TS) mRNA expression levels in the 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines and increased significantly the intracellular concentration of 5-FU in SKBR-3/FU and MDA-MB-453/FU cells. In addition, pyrotinib reduced the ABCG2 mRNA and protein expression levels in SKBR-3/FU and MDA-MB-453/FU cells and downregulated the protein expression levels of pAKT, pHER2, and pHER4 in all four cell lines. After TS or ABCG2 in 5-FU-resistant breast cancer cells was knocked down, the sensitivity of SKBR-3/FU and MDA-MB-453/FU cells to 5-FU was restored. Moreover, in vivo experiments demonstrated that pyrotinib in combination with 5-FU more effectively inhibited SKBR-3/FU tumor growth than either pyrotinib or 5-FU alone. In conclusion, our findings suggest that pyrotinib could restore sensitivity of 5-FU-resistant HER2+ breast cancer cells to 5-FU through downregulating the expression levels of TS and ABCG2.

To explore the myocardial protective effect of Neuregulin-4 (NRG-4) gene expression on spontaneous hypertension (SHR) rats and its mechanism through mediating the activation of the ErbB signaling pathway, this study was conducted. For this purpose, forty 24-week-old male SPF SHR rats were selected as the experimental group, and 10 age and sex-matched Wistar Kyoto (WKY) rats were selected as the control group. Cardiac tissues were collected for hematoxylin-eosin (HE) staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining, Masson staining, and immunohistochemical staining. Following tail vein injection of recombinant lentiviral vectors, the experimental groups were constructed as the control group (SHR rats without any treatment), Empty vector group (Empty Vector transfection), shRNA negative control (NC) group (LV-shRNA-NRG-4 NC transfection to silence the expression of NRG-4), shRNA group (LV-shRNA-NRG-4 transfection), pcDNA3.1(-) NC group (pcDNA3.1(-)-NRG-4 empty vector transfection) and pcDNA3.1(-) group (pcDNA3.1(-)-NRG-4 transfection to overexpress NRG-4). Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to detect the expression levels In addition, methyl thiazolyl tetrazolium salt (MTT) assay and flow cytometry were performed to detect the proliferation and apoptosis of cardiomyocytes, respectively. Results showed that in the SHR group, the cardiomyocytes showed hypertrophy, disordered arrangement, hyperchromatic nucleus, irregular shape, obvious rupture of myocardial fibers, and obvious proliferation of fibrous stroma; obvious myocardial fibrosis, and there were more blue collagen fibers around cardiomyocytes and myocardial arterioles; cardiomyocytes were swollen, muscle fibers arranged disorderly, collagen around the coronary artery and myocardial interstitium increased significantly with a cross-linking appearance; besides, compared with WKY group, the apoptosis index of cardiomyocytes in SHR group was significantly increased (P0.05). While shRNA group showed decreased expressions of NRG-4, ErbB2, ErbB4, MMP2, TGFβ1, α-SMA and Bcl-2, while increased Caspase3 and Bax expressions, as well as promoted cell proliferation and cell apoptosis when compared with the shRNA NC group (P

Schizophrenia is a common mental disorder affecting patients’ thoughts, behavior, and cognition. Recently, the NRG1/ErbB4 signaling pathway emerged as a candidate therapeutic target for schizophrenia. This study investigates the effects of aripiprazole and sertindole on the NRG1/ErbB4 and PI3K/AKT/mTOR signaling pathways in ketamine-induced schizophrenia in rats. Young male Wistar rats received ketamine (30 mg/kg, intraperitoneally) for 5 consecutive days and aripiprazole (3 mg/kg, orally) or sertindole (2.5 mg/kg, orally) for 14 days. The proposed pathway was investigated by injecting LY294002 (a selective PI3K inhibitor) (25 μg/kg, intrahippocampal injection) 30 min before the drugs. Twenty-four hours after the last injection, animals were subjected to behavioral tests: the open field test, sucrose preference test, novel object recognition task, and social interaction test. Both aripiprazole and sertindole significantly ameliorated ketamine-induced schizophrenic-like behavior, as expected, because of their previously demonstrated antipsychotic activity. Besides, both drugs alleviated ketamine-induced oxidative stress and neurotransmitter level changes in the hippocampus. They also increased the gamma-aminobutyric acid and glutamate levels and glutamate decarboxylase 67 and parvalbumin mRNA expression in the hippocampus. Moreover, aripiprazole and sertindole increased the NRG1 and ErbB4 mRNA expression levels and PI3K, p-Akt, and mTOR protein expression levels. Interestingly, pre-injecting LY294002 abolished all the effects of the drugs. This study reveals that the antipsychotic effects of aripiprazole and sertindole are partly due to oxidative stress reduction as well as NRG1/ErbB4 and PI3K/AKT/mTOR signaling pathways activation. The NRG1/ErbB4 and PI3K signaling pathways may offer a new therapeutic approach for treating schizophrenia in humans.

Like all receptor tyrosine kinases (RTKs), ErbB4 signals through a canonical signaling involving phosphorylation cascades. However, ErbB4 can also signal through a non-canonical mechanism whereby the intracellular domain is released into the cytoplasm by regulated intramembrane proteolysis (RIP) and translocates to the nucleus where it regulates transcription. These different signaling mechanisms depend on the generation of alternative spliced isoforms, a RIP cleavable ErbB4-JMa and an uncleavable ErbB4-JMb. Non-canonical signaling by ErbB4-JMa has been implicated in the regulation of brain, heart, mammary gland, lung, and immune cell development. However, most studies on non-canonical ErbB4 signaling have been performed in vitro due to the lack of an adequate mouse model. We created an ErbB4-JMa specific knock out mouse and demonstrate that RIP-dependent, non-canonical signaling by ErbB4-JMa is required for the regulation of GFAP expression during cortical development. We also show that ErbB4-JMa signaling is not required for the development of the heart, mammary glands, sensory ganglia. Furthermore, we identify genes whose expression during cortical development is regulated by ErbB4, and show that the expression of three of them, CRYM and DBi, depend on ErbB4-JMa whereas WDFY1 relies on ErbB4-JMb. Thus, we provide the first animal model to directly study the roles of ErbB4-JMa and non-canonical ErbB4 signaling in vivo.

Patients with breast cancer frequently encounter a dismal prognosis due to the lack of effective and curative therapies. MicroRNAs (miRNAs) are aberrantly regulated in many types of cancer and have been recognized to play crucial roles in cancer progression. We performed a preclinical investigation of the anti-cancer effect of etoposide and microRNA-205-5p (miRNA-205-5p) and their relationship in MCF-7 cells.Two cell culture systems, namely monolayers and spheroids, were employed for evaluating the effect of etoposide and miRNA-205-5p on cell proliferation and migration. Real time quantitative polymerase chain reaction was used for the measurement of mRNA and miRNA levels. Luciferase and western blot assays were utilized for the validation of the target gene of miRNA-205-5p.Treatment with etoposide, suppressed both cell proliferation and migration in MCF-7 monolayers. Also, the growth of MCF-7 spheroids as demonstrated by size measurements was inhibited by etoposide treatment. Furthermore, etoposide was found to upregulate the level of miRNA-205-5p. Over-expression of miRNA-205-5p inhibits cell proliferation and migration by directly targeting Erb-B2 receptor tyrosine kinase 4 (ERBB4).miRNA-205-5p may act as an important mediator of the anti-cancer effect of etoposide and miRNA-205-5p-based therapy may expand the therapeutic opportunities for breast cancer.

Pathologic cardiac remodeling and dysfunction are the most common complications of type 2 diabetes. Physical exercise is important in inhibiting myocardial pathologic remodeling and restoring cardiac function in diabetes. The mitochondrial-derived peptide MOTS-c has exercise-like effects by improving insulin resistance, combatting hyperglycemia, and reducing lipid accumulation. We investigated the effects and transcriptomic profiling of MOTS-c and aerobic exercise on cardiac properties in a rat model of type 2 diabetes which was induced by feeding a high fat high sugar diet combined with an injection of a low dose of streptozotocin. Both aerobic exercise and MOTS-c treatment reduced abnormalities in cardiac structure and function. Transcriptomic function enrichment analysis revealed that MOTS-c had exercise-like effects on inflammation, myocardial apoptosis, angiogenesis and endothelial cell proliferation and migration, and showed that the NRG1-ErbB4 pathway might be an important component in both MOTS-c and exercise induced attenuation of cardiac dysfunction in diabetes. Moreover, our findings suggest that MOTS-c activates NRG1-ErbB4 signaling and mimics exercise-induced cardio-protection in diabetes.

Consolidated memories influence later learning and cognitive processes when new information is overlapped with previous events. To reveal which cellular and molecular factors are associated with this proactive interference, we challenged mice with odor–reward associative learning followed by a reversal-learning task. The results showed that genetical ablation of ErbB4 in parvalbumin (PV)-positive interneurons improved performance in reversal-learning phase, with no alteration in learning phase, supporting that PV interneuron ErbB4 is required for proactive interference. Mechanistically, olfactory learning promoted PV interneuron excitatory synaptic plasticity and direct binding of ErbB4 with presynaptic Neurexin1β (NRXN1β) and postsynaptic scaffold PSD-95 in the prefrontal cortex. Interrupting ErbB4–NRXN1β interaction impaired network activity-driven excitatory inputs and excitatory synaptic transmission onto PV interneurons. Neuronal activity-induced ErbB4-PSD-95 association facilitated transsynaptic binding of ErbB4–NRXN1β and excitatory synapse formation in ErbB4-positive interneurons. Furthermore, ErbB4–NRXN1β binding was responsible for the activity-regulated activation of ErbB4 and extracellular signal-regulated kinase (ERK) 1/2 in PV interneurons, as well as synaptic plasticity-related expression of brain-derived neurotrophic factor (BDNF). Correlatedly, blocking ErbB4–NRXN1β coupling in the medial prefrontal cortex of adult mice facilitated reversal learning of an olfactory associative task. These findings provide novel insight into the physiological role of PV interneuron ErbB4 signaling in cognitive processes and reveal an associative learning-related transsynaptic NRXN1β-ErbB4-PSD-95 complex that affects the ERK1/2-BDNF pathway and underlies local inhibitory circuit plasticity and proactive interference.

Cell-cell communication plays a central role in the guidance of migrating neurons during the development of the cerebral cortex. Neuregulins (NRGs) are essential mediators for migration and maintenance of the radial glial scaffold. We show, in this study that soluble NRG reduces neuronal motility, causes transition of bipolar cells to multipolar ones, and induces neuronal mitosis. Blocking the NRG receptor, ErbB4, results in reduction of neuron-neuron and neuron-radial glial contacts and causes an increase in neuronal motility. Blocking the radial glial metabotropic glutamate receptor 5 (mGluR5), the nonselective cation channel transient receptor potential 3 (TRPC3), or matrix metalloproteinases (MMPs) results in similar effects as ErbB4 blockade. Soluble NRG counteract the changes in motility pattern. Stimulation of other radial glial G-protein-coupled receptors (GPCRs), such as muscarinic acetylcholine receptors or endothelin receptors counteract all the effect of mGluR5 blockade, but not that of ErbB4, TRPC3, and MMP blockade. The results indicate that neurotransmitters and endothelins acting on radial glial GPCRs are, through proteolytic NRG/ErbB4 activation, able to modify the migratory behavior of neurons.

The purpose of this study was to explore the significance of the neuregulin-1/ErbB signaling pathway and its effect on Sox10 expression in the course of the differentiation of mouse bone marrow mesenchymal stem cells into Schwann-like cellsThe experiment was conducted with three groups-control, TAK 165, and HRG-off. In the control group, we used the classical induction method of adding β-ME, RA, FSK, b-FGF, PDGF, and neuregulin (HRG); the cells were collected on the 7Our results showed that the proliferation of Schwann cells was reduced and apoptosis was increased in the TAK 165 group and the HRG-off group. Sox10 was stably expressed and NRG-1, ErbB2, and ErbB3 increased in the control group. However, the expression of Sox10 in the TAK 165 group was obviously decreased at the end of induced differentiation; meanwhile, the degree of stem cell differentiation also decreased.the neuregulin-1/ErbB signaling pathway plays an important role in the differentiation of bone marrow mesenchymal stem cells into Schwann-like cells and can promote the maintenance of Sox10 。.

Pancreatic ductal adenocarcinoma (PDAC) will soon belong to the top three cancer killers. The only approved specific PDAC therapy targets the epidermal growth factor receptor (EGFR). Although EGFR is a crucial player in PDAC development, EGFR‐based therapy is disappointing. In this study, we evaluated the role of the EGFR ligand betacellulin (BTC) in PDAC. The expression of BTC was investigated in human pancreatic cancer specimen. Then, we generated a BTC knockout mouse model by CRISPR/Cas9 technology and a BTC overexpression model. Both models were crossed with the Ptf1aCre/+;KRASG12D/+ (KC) mouse model (B−/−KC or BKC, respectively). In addition, EGFR, ERBB2, and ERBB4 were investigated by the pancreas‐specific deletion of each receptor using the Cre‐loxP system. Tumor initiation and progression were analyzed in all mouse lines, and the underlying molecular biology of PDAC was investigated at different time points. BTC is expressed in human and murine PDAC. B−/−KC mice showed a decelerated PDAC progression, associated with decreased EGFR activation. BKC mice developed severe PDAC with a poor survival rate. The dramatically increased BTC‐mediated tumor burden was EGFR‐dependent, but also ERBB4 and ERBB2 were involved in PDAC development or progression, as depletion of EGFR, ERBB2, or ERBB4 significantly improved the survival rate of BTC‐mediated PDAC. BTC increases PDAC tumor burden dramatically by enhanced RAS activation. EGFR signaling, ERBB2 signaling, and ERBB4 signaling are involved in accelerated PDAC development mediated by BTC indicating that targeting the whole ERBB family, instead of a single receptor, is a promising strategy for the development of future PDAC therapies., We have shown that BTC overexpression deteriorates pancreatic ductal adenocarcinoma (PDAC) prognosis in mice. BTC enhances RAS activity, thereby potentially transforming acinar to duct cells. BTC involves not only EGFR activation, it also activates ERBB2 and ERBB4 to induce accelerated PDAC development and progression. A partial disease rescue upon loss of ERBB2 and ERBB4 implies that both receptors are potent oncogenes in PDAC.

ERBB4 is a member of the epidermal growth factor receptor (EGFR)/ERBB subfamily of receptor tyrosine kinases that regulates cellular processes including proliferation, migration, and survival. ERBB4 signaling is involved in embryogenesis and homeostasis of healthy adult tissues, but also in human pathologies such as cancer, neurological disorders, and cardiovascular diseases. Here, an MS-based analysis revealed the Vav guanine nucleotide exchange factor 3 (VAV3), an activator of Rho family GTPases, as a critical ERBB4-interacting protein in breast cancer cells. We confirmed the ERBB4–VAV3 interaction by targeted MS and coimmunoprecipitation experiments and further defined it by demonstrating that kinase activity and Tyr-1022 and Tyr-1162 of ERBB4, as well as the intact phosphotyrosine-interacting SH2 domain of VAV3, are necessary for this interaction. We found that ERBB4 stimulates tyrosine phosphorylation of the VAV3 activation domain, known to be required for guanine nucleotide exchange factor (GEF) activity of VAV proteins. In addition to VAV3, the other members of the VAV family, VAV1 and VAV2, also coprecipitated with ERBB4. Analyses of the effects of overexpression of dominant-negative VAV3 constructs or shRNA-mediated down-regulation of VAV3 expression in breast cancer cells indicated that active VAV3 is involved in ERBB4-stimulated cell migration. These results define the VAV GEFs as effectors of ERBB4 activity in a signaling pathway relevant for cancer cell migration.

Ectodomain shedding is a post-translational modification mechanism by which the entire extracellular domain of membrane proteins is liberated through juxtamembrane processing. Because shedding rapidly and irreversibly alters the characteristics of cells, this process is properly regulated. However, the molecular mechanisms governing the propensity of membrane proteins to shedding are largely unknown. Here, we present evidence that negatively charged amino acids within the stalk region, an unstructured juxtamembrane region at which shedding occurs, contribute to shedding susceptibility. We show that two activated leukocyte cell adhesion molecule (ALCAM) protein variants produced by alternative splicing have different susceptibilities to ADAM metallopeptidase domain 17 (ADAM17)-mediated shedding. Of note, the inclusion of a stalk region encoded by a 39-bp-long alternative exon conferred shedding resistance. We found that this alternative exon encodes a large proportion of negatively charged amino acids, which we demonstrate are indispensable for conferring the shedding resistance. We also show that the introduction of negatively charged amino acids into the stalk region of shedding-susceptible ALCAM variant protein attenuates its shedding. Furthermore, we observed that negatively charged amino acids residing in the stalk region of Erb-B2 receptor tyrosine kinase 4 (ERBB4) are indispensable for its shedding resistance. Collectively, our results indicate that negatively charged amino acids within the stalk region interfere with the shedding of multiple membrane proteins. We conclude that the composition of the stalk region determines the shedding susceptibility of membrane proteins.

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders leading to infertility in women affecting reproductive, endocrine and metabolic systems. Recent genomewide association studies on PCOS cohorts revealed a single nucleotide polymorphism (SNP) in the ERBB4 receptor tyrosine kinase 4 gene, but its role in ovary development or during folliculogenesis remains poorly understood. Since no genetic animal models mimicking all PCOS reproductive features are available, we conditionally deleted Erbb4 in murine granulosa cells (GCs) under the control of Amh promoter. While we have demonstrated that Erbb4 deletion displayed aberrant ovarian function by affecting the reproductive function (asynchronous oestrous cycle leading to few ovulations and subfertility) and metabolic function (obesity), their ovaries also present severe structural and functional abnormalities (impaired oocyte development). Hormone analysis revealed an up-regulation of serum luteinizing hormone, hyperandrogenism, increased production of ovarian and circulating anti-Müllerian hormone. Our data implicate that Erbb4 deletion in GCs leads to defective intercellular junctions between the GCs and oocytes, causing changes in the expression of genes regulating the local microenvironment of the follicles. In vitro culture assays reducing the level of Erbb4 via shRNAs confirm that Erbb4 is essential for regulating Amh level. In conclusion, our results indicate a functional role for Erbb4 in the ovary, especially during folliculogenesis and its reduced expression plays an important role in reproductive pathophysiology, such as PCOS development.

The neuregulins (Nrgs 1–4) are a family of signaling molecules that play diverse roles in the nervous system. Nrg1 has been implicated in the formation of synapses and in synaptic plasticity. Previous studies have shown Nrg1 can affect neurite outgrowth in several neuronal populations, while the role of Nrg2 and Nrg3 in this process has remained understudied. The Nrgs can bind and activate the ErbB4 receptor tyrosine kinase which is preferentially expressed in GABAergic interneurons in the rodent hippocampus and cerebral cortex. In the present study, we evaluated the effects of Nrgs 1, 2, and 3 on neurite outgrowth of dissociated rat cortical ErbB4-positive (+)/GABA+ interneurons in vitro. All three Nrgs were able to promote neurite outgrowth during the first 2 days in vitro, with increases detected for both the axon (116–120%) and other neurites (100–120%). Increases in the average number of primary and secondary neurites were also observed. Treatment with the Nrgs for an additional 3 days promoted an increase in axonal length (86–96%), with only minimal effects on the remaining neurites (8–13%). ErbB4 expression persisted throughout the dendritic arbor and cell soma at all stages examined, while its expression in the axon was transient and declined with cell maturation. ErbB4 overexpression in GABAergic neurons promoted neurite outgrowth, an effect that was potentiated by Nrg treatment. These results show that Nrgs 1, 2, and 3 are each capable of influencing dendritic and axonal growth at early developmental stages in GABAergic neurons grown in vitro.

Major depressive disorder (MDD) is a highly prevalent debilitating psychiatric disease and a serious public health problem worldwide. Brain structural MRI and postmortem studies on patients with depression have revealed changes in the anatomy and functionality in various brain regions, including the amygdala, thalamus, hippocampus, and prefrontal cortex (PFC). The alterations in these brain regions could be a result, in part, of the dysregulation of the neurotrophic factors. Neuregulin1 (NRG1) is one of the neurotrophic factors, and our previous study showed that the NRG1-ErbB4 signaling pathway plays a critical role in epilepsy. In this study, we established a chronic social defeat stress (CSDS) model to investigate the role of the NRG1-ErbB4 signaling pathway in depression-like behaviors. In CSDS mice, we found that the NRG1 protein expression levels were significantly decreased both in the medial prefrontal cortex (mPFC) and hippocampus, while phosphorylated ErbB4 only decreased in the mPFC. In addition, lateral ventricle NRG1 administration significantly rescued depression-like behaviors in the susceptible group. The current study suggests that the NRG1-ErbB4 signaling pathway may exert a protective role in MDD.

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy, with an overall 5-year survival rate of only 30%. EOC is associated with drug resistance, frequent recurrence, and poor prognosis. A major contributor toward drug resistance might be cancer stem cells (CSCs), which may remain after chemotherapy. Here, we aimed to find therapeutic agents that target ovarian CSCs. We performed a high-throughput screening using the Clinical Compound Library with a sphere culture of A2780 EOCs. Poziotinib, a pan-human epidermal growth factor receptor (HER) inhibitor, decreased sphere formation, viability, and proliferation, and induced G1 cell cycle arrest and apoptosis in ovarian CSCs. In addition, poziotinib suppressed stemness and disrupted downstream signaling of Wnt/β-catenin, Notch, and Hedgehog pathways, which contribute to many characteristics of CSCs. Interestingly, HER4 was overexpressed in ovarian CSCs and Poziotinib reduced the phosphorylation of STAT5, AKT, and ERK, which are regulated by HER4. Our results suggest that HER4 may be a promising therapeutic target for ovarian CSCs, and that poziotinib may be an effective therapeutic option for the prevention of ovarian cancer recurrence.

Background Amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) includes a large spectrum of neurodegenerative disorders. Objective To identify the relationship of ErbB4 mutation and ALS/FTD. Methods Here, we report an atypical case of frontal variant behavioral abnormalities at the initial stage, a stable plateau stage of 5 years, and paralysis involving both upper and lower motor neurons followed by progressive cognitive dysfunction at the advanced stage. The clinical findings suggested a diagnosis of ALS/FTD, and genetic testing revealed erb-b2 receptor tyrosine kinase 4 (ErbB4) heterozygous mutation (c.2136 T>G, p.I712M), identified in an ALS pedigree previously. We modeled mutant ErbB4 protein through the SWISS-MODEL Server, and speculated on the structural change caused by the mutation. We also identified that ErbB4 (I712M) mutation led to reduced auto-phosphorylation of ErbB4 upon neuregulin-1 (NRG1) stimulation. Results A functional analysis of ErbB4 mutation demonstrated an obviously decreased auto-phosphorylation of ErbB4 involving in the pathogenesis of ALS/FTD. Conclusion We firstly found ErbB4 mutation to be identified in ALS/FTD.

Osteosarcoma is the most common primary malignant bone tumor, which occurs in adolescents. As reported by our previous studies, HER4 indicates a poor prognosis of primary osteosarcoma. However, its mechanisms in the pathogenesis of osteosarcoma have not yet been studied. The purpose of this study was to investigate the role of HER4 in osteosarcoma and whether the PI3K/AKT pathway is involved. In this study, western blot analysis was used to investigate the expression of HER4 protein in osteosarcoma tissues and cell lines. CCK8 and transwell assays were used to detect the effects of HER4 on the proliferation, migration, and invasion of osteosarcoma cells in vitro. The effects of HER4 on the growth and metastasis of osteosarcoma in vivo were detected by tumor formation and immunofluorescence in nude mice. The role of the PI3K/AKT pathway in HER4 regulation of the growth and metastasis of osteosarcoma was examined by western blot analysis and immunofluorescence assay. We found that HER4 protein was highly expressed in clinical osteosarcoma specimens and osteosarcoma cells. HER4 markedly promoted the proliferation, migration, and invasion of osteosarcoma cells in vitro as well as the growth and metastasis of osteosarcoma in vivo. HER4 overexpression upregulated the expression of phosphorylated protein kinase B (pAKT), proliferation marker antigen Ki67, and metastasis cell marker matrix metalloproteinase 9 (MMP9). Notably, PI3K/AKT inhibitor LY294002 significantly inhibited the effects of HER4 via the downregulation of pAKT, Ki67, and MMP9. Moreover, LY294002 markedly blocked the effects of HER4-induced upregulation of tumor malignancy. The present study suggests that HER4 may promote the growth and metastasis of osteosarcoma via the PI3K/AKT pathway. The HER4/PI3K/AKT pathway could serve as a potential target for the treatment of osteosarcoma.

ErbB4 is a regulator in lung development and disease. Prenatal infection is an important risk factor for the delay of morphologic lung development, while promoting the maturation of the surfactant system. Bone marrow–derived mesenchymal stem cells (BMSCs) have the potential to prevent lung injury. We hypothesized that BMSCs in comparison with hematopoietic control stem cells (HPSCs) minimize the lipopolysaccharide (LPS)-induced lung injury only when functional ErbB4 receptor is present. We injected LPS and/or murine green fluorescent protein–labeled BMSCs or HPSCs into the amniotic cavity of transgenic ErbB4heart mothers at gestational day 17. Fetal lungs were analyzed 24 h later. BMSCs minimized significantly LPS-induced delay in morphological lung maturation consisting of a stereologically measured increase in mesenchyme and septal thickness and a decrease of future airspace and septal surface. This effect was more prominent and significant in the ErbB4heart+/− lungs, suggesting that the presence of functioning ErbB4 signaling is required. BMSC also diminished the LPS induced increase in surfactant protein (Sftp)a mRNA and decrease in Sftpc mRNA is only seen if ErbB4 is present. The reduction of morphological delay of lung development and of levels of immune-modulating Sftp was more pronounced in the presence of the ErbB4 receptor. Thus, ErbB4 may be required for the protective signaling of BMSCs.

Polycystic ovary syndrome (PCOS) is an oligogenic condition characterised by hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology. Previously, European and Han Chinese populations identified different susceptibility loci, of which ERBB4 (rs1351592) was strongly associated with PCOS. Our study aimed to investigate the association of ERBB4 Single Nucleotide Polymorphism (SNP), rs1351592 with PCOS in Pakistani women of Hazara region. Fifty PCOS patients and 14 healthy women were recruited and SNP was replicated using ARMS-PCR and sequencing. The study showed that Luteinising Hormone (LH), Follicle Stimulating Hormone (FSH), and Testosterone (T) were significantly elevated in patients compared to controls (P0.05). Overall, the frequency of G allele was higher than C allele and the SNP lacked significant association with PCOS. This is the first study demonstrating the association of ERBB4 SNP, rs1351592 with PCOS in Pakistani population. Further research using larger population size will help to estimate the role of ERBB4 SNP as potential biomarker for disease diagnosis.

The function of miR-551b has been widely reported in various human cancers, and its dysregulation in papillary thyroid cancer (PTC) has also been disclosed, implying its potential regulator role in PTC. The aim of the study was to evaluate the function of miR-551b in PTC development and its potential mechanism. miR-551b was evaluated in PTC tissues and cells by RT-qPCR and associated with the clinicopathological features of patients. The biological effect of miR-551b on cellular processes of PTC was assessed with the CCK8 proliferation assay and the Transwell migration and invasion assay. The potential molecular mechanism was estimated with the dual-luciferase reporter assay. miR-551b was significantly upregulated in PTC, which showed a close relationship with the malignancy and development of PTC patients. miR-551b served as a prognostic biomarker negatively related to patients’ survival together with the TNM stage. The overexpression of miR-551b exerted promoted effect on the development-related cellular processes of PTC, which was reversed by the overexpression of ERBB4. In conclusion, miR-551b could predict the poor prognosis of PTC patients and serve as a tumor promoter via suppressing ERBB4.

Sharp wave ripples (SW-Rs) in the hippocampus are synchronized bursts of hippocampal pyramidal neurons (PyNs), critical for spatial working memory. However, the molecular underpinnings of SW-Rs remain poorly understood. We show that SW-Rs in hippocampal slices from both male and female mice were suppressed by neuregulin 1 (NRG1), an epidermal growth factor whose expression is enhanced by neuronal activity. Pharmacological inhibition of ErbB4, a receptor tyrosine kinase for NRG1, increases SW-R occurrence rate in hippocampal slices. These results suggest an important role of NRG1-ErbB4 signaling in regulating SW-Rs. To further test this notion, we characterized SW-Rs in freely moving male mice, chemical genetic mutant mice, where ErbB4 can be specifically inhibited by the bulky inhibitor 1NMPP1. Remarkably, SW-R occurrence was increased by 1NMPP1. We found that 1NMPP1 increased the firing rate of PyN neurons, yet disrupted PyN neuron dynamics during SW-R events. Furthermore, 1NMPP1 increased SW-R occurrence during both nonrapid eye movement (NREM) sleep states and wake states with a greater impact on SW-Rs during wake states. In accord, spatial working memory was attenuated in male mice. Together these results indicate that dynamic activity of ErbB4 kinase is critical to SW-Rs and spatial working memory. This study reveals a novel regulatory mechanism of SW-Rs and a novel function of the NRG1-ErbB4 signaling.SIGNIFICANCE STATEMENTSharp wave ripples (SW-Rs) are a hippocampal event, important for memory functioning. Yet the molecular pathways that regulate SW-Rs remain unclear. Neuregulin 1 (NRG1), previously known to be increased in pyramidal neuron's (PyNs) in an activity dependent manner, signals to its receptor, ErbB4 kinase, that is in important regulator of GABAergic transmission and long-term potentiation in the hippocampus. Our findings demonstrate that SW-Rs are regulated by this signaling pathway in a dynamic manner. Not only so, we show that this signaling pathway is dynamically needed for spatial working memory. These data suggest a molecular signaling pathway, NRG1-ErbB4, that regulates an important network event of the hippocampus, SW-Rs, that underlies memory functioning.

Receptor Tyrosine Kinases of the Epidermal Growth Factor Receptor Family play a pivotal role as drivers of carcinogenesis and uncontrolled cell growth for a variety of malignancies, not least for breast cancer. Besides the estrogen receptor, the HER2 receptor was and still is a representative marker for advanced taxonomic sub-differentiation of breast cancer and emerged as one of the first therapeutic targets for antibody based therapies. Since the approval of trastuzumab for the therapy of HER2-positive breast cancer in 1998 anti-HER2 treatment strategies are being modified, refined, and successfully combined with complementary treatments, nevertheless there is still potential for improvement. The HER2 relatives, namely HER1 (i.e., EGFR), HER3 and HER4 share a high degree of molecular homology and together form a functional unit for signal transmission. Under regular conditions, receptor coexpression patterns and receptor interaction represent key parameters for signaling robustness, which ensures cellular growth control and enables tissue differentiation. In addition, treatment efficiency of e.g., an anti-HER2 targeting is substantially determined by the expression pattern of HER receptors on target cells. Within the receptor family, the HER4 plays a particular role and is engaged in exceptional signaling activities. A favorable prognostic impact has been attributed to HER4 expression in breast cancer under specific molecular conditions. HER4-specific cellular effects are initially determined by a ligand-dependent or -independent receptor activation. Essential processes as cell growth and proliferation, cell differentiation, and apoptotic cell death can be initiated by this receptor. This review gives an overview of the role of HER4 in normal and malignant breast epithelial cells and tissues. Specific mechanism of HER4 activation and subsequent intracellular signaling will be described by taking a focus on effects provoked by receptor shedding. HER4 activities and specific effects will be correlated to breast cancer subtypes and the impact of HER4 on course and outcome of disease will be considered. Moreover, current and potential therapeutic approaches will be discussed.

Background MicroRNAs (MiRNAs) are known to participate in preadipocyte differentiation, but the manner in which miR-146a-5p participates in this process remains unclear. This study was performed to examine the participation of miR-146a-5p in 3T3-L1 cell differentiation. Material and Methods miR-146a-5p expression was upregulated and down-regulated to examine effects on 3T3-L1 cell differentiation. Bioinformatics analysis was performed to predict its target genes, and the signaling pathway it regulates was identified by qRT-PCR and Western blotting. The expression of miR-146a-5p in epididymal adipose tissue from obese mice and in an obese mouse adipose cell model was examined by qRT-PCR. Results 3T3-L1 cells differentiated into mature adipocytes successfully, as verified by increased areas of intracellular lipid droplets and elevated expression of mature adipocyte markers, and these cells had elevated miR-146a-5p expression. The intracellular lipid droplet and triglyceride contents and the expression of mature adipocyte markers were significantly increased in miR-146a-5p–overexpressing 3T3-L1 cells and markedly decreased in miR-146a-5p–inhibited 3T3-L1 cells. ErbB4 was a predicted target gene of miR-146a-5p. In miR-146a-5p–overexpressing 3T3-L1 cells, ErbB4 expression and ERK1/2 phosphorylation were decreased and the expression of PPAR-γ was increased; the opposite was observed in miR-146a-5p–inhibited 3T3-L1 cells. In addition, miR-146a-5p expression was significantly increased in the mouse epididymal adipose tissue and adipose cell model. Conclusions Upregulated miR-146a-5p expression was related to 3T3-L1 cell differentiation. MiR-146a-5p promoted 3T3-L1 cell differentiation by targeting ErbB4 and via the ERK1/2/PPAR-γ signaling pathway.

Acute myocardial infarction is the leading cause of death and disability worldwide. Reperfusion is the main treatment method. However, ischemia-reperfusion (I/R) injury aggravates tissue and cell damage. In this study, we aim to find a strategy to reduce I/R injury and promote cardiac function recovery. The expression of AK003290 was downregulated in I/R injury both

HER4 is a receptor tyrosine kinase that is required for the evolution of normal body systems such as cardiovascular, nervous, and endocrine systems, especially the mammary glands. It is activated through ligand binding and activates MAPKs and PI3K/AKT pathways. HER4 is commonly expressed in many human tissues, both adult and fetal. It is important to understand the role of HER4 in the treatment of many disorders. Many studies were also conducted on the role of HER4 in tumors and its tumor suppressor function. Mostly, overexpression of HER4 kinase results in cancer development. In the present article, we reviewed the structure, location, ligands, physiological functions of HER4, and its relationship to different cancer types. HER4 inhibitors reported mainly from 2016 to the present were reviewed as well.