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.
Animals ; Glucose ; Male ; Myocardial Infarction/drug therapy* ; Myocardium ; Neuregulin-1 ; Rats ; Rats, Sprague-Dawley ; Stroke Volume ; Ventricular Function, Left

Neuregulin-1 (NRG1) has been shown to be able to protect against focal cerebral ischemia. The aim of the present study was to investigate the neuroprotective effect of NRG1 in primary hippocampal neurons and its underlying mechanism. Our data showed oxygen-glucose deprivation (OGD)-induced cytotoxicity and overexpression of ErbB4 in primary hippocampal neurons. Moreover, pretreatment with NRG1 could inhibit OGD-induced overexpression of ErbB4. In addition, NRG1 significantly attenuated neuronal death induced by OGD. The neuroprotective effect of NRG1 was blocked in ischemic neurons after pretreatment with AG1478, an inhibitor of ErbB4, but not after pretreatment with AG879, an inhibitor of ErbB2. These results indicate an important role of ErbB4 in NRG1-mediated neuroprotection, suggesting that endogenous ErbB4 might serve as a valuable therapeutic target for treating global cerebral ischemia.]]>
Anoxia ; Brain ; Brain Ischemia ; Cell Death ; Cognition ; Hippocampus ; Ischemia ; Neuregulin-1 ; Neurons ; Neuroprotection ; Neuroprotective Agents

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.
Autoimmunity ; Genes, Homeobox ; Genetics ; Genome-Wide Association Study* ; Graves Disease ; Hashimoto Disease ; Humans ; Leukocytes ; Neuregulin-1 ; Phenotype ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; Receptors, Interleukin-2 ; T-Lymphocytes, Cytotoxic ; Thyroid Diseases* ; Thyroid Gland* ; Thyroid Neoplasms* ; Thyrotropin ; Thyroxine

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.
Animals ; Mice ; Mice, Knockout ; Motor Endplate ; Muscle, Skeletal* ; Muscles ; Myelin Sheath ; Neuregulin-1 ; Neuromuscular Junction ; Peripheral Nerves ; Presynaptic Terminals ; Protein-Tyrosine Kinases ; Schwann Cells* ; Synapses* ; Vertebrates

Neuregulin 4 (NRG4) is a kind of protein containing epidermal growth factor (EGF)-like domains, mainly expressed and secreted by brown adipocytes. It specifically activates EGF receptor ErbB4 (v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4) to stimulate cell proliferation, inhibit apoptosis and improve energy metabolism of cells. Increasing evidence has shown that NRG4 plays an important role in epithelial cell-related diseases, cardiovascular diseases, tumors and glycolipid metabolic diseases, and therefore it could be a potential therapeutic target of some diseases.
Animals ; Apoptosis ; Cardiovascular Diseases ; Cell Proliferation ; Energy Metabolism ; Humans ; Metabolic Diseases ; Neoplasms ; Neuregulins ; physiology ; Receptor, ErbB-4 ; physiology ; Signal Transduction

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.
Animals ; Cell Count* ; Coculture Techniques ; Flow Cytometry ; Fluorescent Antibody Technique ; Glial Fibrillary Acidic Protein ; Neuregulin-1 ; Peripheral Nerve Injuries ; Rats* ; RNA, Messenger ; S100 Proteins ; Schwann Cells ; Stem Cells*

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.
Animals ; Blotting, Western ; Cyclophosphamide ; Cystitis, Interstitial* ; Neuregulin-1* ; Protein-Tyrosine Kinases* ; Rats* ; Rats, Sprague-Dawley ; Receptor, erbB-2 ; Regeneration ; RNA, Messenger ; Tyrosine* ; Urinary Bladder* ; Urinary Bladder, Overactive

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.
Action Potentials ; Axons ; Humans ; Myelin Sheath ; Nerve Growth Factors ; Neuregulin-1 ; Peripheral Nerve Injuries ; Peripheral Nerves ; Phosphotransferases ; Plastics* ; Protein Kinases* ; Regeneration ; Schwann Cells ; Transcription Factors

In the present study, we investigate the expression profile of the epidermal growth factor receptor family, which comprises EGFR/ErbB1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4 in oral leukoplakia (LP). The expression of four epidermal growth factor receptor (EGFR) family genes and their ligands were measured in LP tissues from 14 patients and compared with levels in 10 patients with oral lichen planus (OLP) and normal oral mucosa (NOM) from 14 healthy donors by real-time polymerase chain reaction (PCR) and immunohistochemistry. Synchronous mRNA coexpression of ErbB1, ErbB2, ErbB3 and ErbB4 was detected in LP lesions. Out of the receptors, only ErbB4 mRNA and protein was more highly expressed in LP compared with NOM tissues. These were strongly expressed by epithelial keratinocytes in LP lesions, as shown by immunohistochemistry. Regarding the ligands, the mRNA of Neuregulin2 and 4 were more highly expressed in OLP compared with NOM tissues. Therefore, enhanced ErbB4 on the keratinocytes and synchronous modulation of EGFR family genes may contribute to the pathogenesis and carcinogenesis of LP.
Adult ; Aged ; Amphiregulin ; Betacellulin ; EGF Family of Proteins ; Epidermal Growth Factor ; metabolism ; Epiregulin ; Female ; Gene Expression Profiling ; Glycoproteins ; metabolism ; Heparin ; metabolism ; Heparin-binding EGF-like Growth Factor ; Humans ; Intercellular Signaling Peptides and Proteins ; metabolism ; Keratinocytes ; metabolism ; Leukoplakia, Oral ; metabolism ; Lichen Planus, Oral ; metabolism ; Ligands ; Male ; Middle Aged ; Mouth Mucosa ; metabolism ; Nerve Growth Factors ; Neuregulins ; metabolism ; RNA, Messenger ; metabolism ; Real-Time Polymerase Chain Reaction ; Receptor, Epidermal Growth Factor ; metabolism ; Receptor, ErbB-2 ; metabolism ; Receptor, ErbB-3 ; metabolism ; Receptor, ErbB-4 ; Receptors, Cell Surface ; metabolism ; Transforming Growth Factor alpha ; metabolism ; Up-Regulation ; physiology

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.
Breast Neoplasms/enzymology/*genetics/*metabolism ; Butadienes/pharmacology ; Cell Line, Tumor ; Dose-Response Relationship, Drug ; Enzyme Inhibitors/pharmacology ; Female ; Gene Expression ; Gene Expression Regulation, Neoplastic/drug effects ; Humans ; MAP Kinase Signaling System ; MCF-7 Cells ; Matrix Metalloproteinase 1/*genetics/metabolism ; Matrix Metalloproteinase 9/*genetics/metabolism ; Neuregulin-1/*pharmacology ; Nitriles/pharmacology ; Phosphatidylinositol 3-Kinases/metabolism ; Protein Kinase Inhibitors/pharmacology ; Protein Multimerization ; Proto-Oncogene Proteins c-akt/metabolism ; Quinazolines/pharmacology ; Receptor, erbB-2/genetics/*metabolism ; Receptor, erbB-3/*metabolism