Neuregulin Research Articles

Endothelial NRG-1 knock-out causes left ventricle dilation in the presence and absence of angiotensin II administration

Abstract Introduction Neuregulin-1 (NRG-1) is a growth factor derived from endothelial cells and belongs to the epidermal growth factor (EGF) family. While NRG-1 is expressed by various cell types, including epithelial cells, glial cells, neurons, and myocytes, the primary source of NRG-1 is considered to be the endothelium. NRG-1 exerts its effects through the EGF receptors ERBB2, ERBB3, and ERBB4. Upon ligand binding, these receptors dimerize and become phosphorylated, leading to downstream signaling that impacts tissue proliferation, differentiation, and survival. The biological role of NRG-1 is intricate due to its isoforms and differential expression across distinct tissue types. In our study, we investigated the impact of endothelial NRG-1 knock-out (KO) on the heart, both in the presence and absence of angiotensin II (ANGII) treatment. ANGII serves as a trigger for NRG-1 upregulation. Methods C57BL/6N-VE-cad-cre-ERT2 mice were crossbred with C57BL/6N-NRG F/F mice, enabling endothelial-specific NRG-1 knockout (KO) using a tamoxifen-inducible promoter. At eight weeks of age, C57BL/6N-VE-cad-cre-ERT2-NRG F/F mice received tamoxifen (1 mg) or vehicle injections for nine consecutive days intraperitoneally (i.p.) to induce the KO. Two days after injection, osmotic minipumps were subcutaneously implanted, releasing a stable dose of angiotensin II (ANGII) at a rate of 400 ng·kg·min⁻¹ for a four-week period. Sham operations served as controls (SHAM). In the final week of treatment, high-frequency ultrasound imaging was performed to assess cardiac function and dimensions. After four weeks of ANGII treatment, mice were sacrificed, and organs were weighed and harvested for further molecular analysis. Results High-frequency ultrasound revealed left ventricle dilation in the absence of endothelial NRG-1, both in ANGII-treated and SHAM-treated mice. This was demonstrated by a significant increase in systolic and diastolic left ventricle internal diameter (LVID) in the endothelial NRG-1 KO groups compared to their respective controls. Additionally, systolic and diastolic LV volume (LV-vol) was significantly increased in the endothelial NRG-1 KO groups, regardless of ANGII treatment. Notably, there was no difference in LVID and LV-vol between SHAM and ANGII-treated groups in the presence of endothelial NRG-1, indicating that LV dilation is primarily due to the absence of endothelial NRG-1 rather than ANGII. Furthermore, heart weights of the endothelial NRG-1 KO mice were significantly increased compared to the control groups, as shown in Figure 1. Conclusion Our study demonstrates that endothelial NRG-1 KO leads to LV dilation, suggesting a crucial role for endothelial-secreted NRG-1 in maintaining normal LV function in adulthood. Further research is needed to fully understand the precise role of NRG-1 in LV homeostasis.

The development of small-molecule ERBB4 agonists as a treatment for heart failure

Abstract The neuregulin-1 (NRG1)/ERBB4 signaling pathway has emerged as a cardioprotective pathway and is a promising target for the treatment of chronic heart failure. Activation of ERBB4 signaling is known to decrease cardiomyocyte cell death and hypertrophy, and fibroblast collagen synthesis. Recombinant NRG1 (rNRG1) is currently tested in phase III clinical trials for heart failure, but its need for intravenous administration is a disadvantage. In an attempt to circumvent this, we hypothesized that small-molecule-induced activation of ERBB4 is feasible and would recapitulate the effects of its natural ligand on myocytes and fibroblasts. To this end, we screened 10,240 compounds for their ability to induce homodimerization of ERBB4. We identified a series of 8 similar compounds (named EF-1 – EF-8) that concentration-dependently induced ERBB4 dimerization, with EF-1 being the most potent and effective compound (n = 4-5 independent repeats in each group; Emax = 27.9 ± 4.8% relative to NRG1, EC50 = 10.5 ± 4.5 x 10-6). EF-1 showed neither cytotoxicity nor increased cell proliferation of tumor cell lines. In vitro, EF-1 significantly decreased in a concentration-dependent manner hydrogen peroxide–induced cardiomyocyte cell death (n = 4 independent repeats in each group; P<0.0001 compared to siERBB4, Fig. 1A), angiotensin-II (AngII)-induced cardiomyocyte hypertrophy (n = 20 individual cardiomyocytes in each group; P<0.0001 compared to AngII/vehicle, Fig. 1B), and collagen expression in cultured human fibroblasts (n = 3 independent repeats in each group; P=0.03 compared to siERBB4, Fig. 1C). The observed effects in cultured cardiomyocytes and fibroblasts could be abrogated by siRNA targeting ERBB4, indicating that they were mediated by ERBB4. Moreover, when used in vivo, EF-1 (2 mg/kg/day) significantly decreased AngII-induced left ventricular Col1a1 and Col3a1 mRNA expression (n = 4-5 mice in each group; P=0.02 and P=0.004 compared to AngII/vehicle, respectively) and inhibited AngII-induced myocardial total and interstitial fibrosis in wild-type mice (n = 4-5 mice in each group, Fig. 2), but not in Erbb4-null mice. Moreover, EF-1 decreased acute cardiotoxicity (assessed by troponin release) in wild-type mice treated with doxorubicin (DOX; n = 8-9 mice in each group; P<0.0001 compared to DOX/vehicle), but not in Erbb4-null mice. In conclusion, we show that small-molecule-induced ERBB4 dimerization and activation is feasible, and recapitulates anti-fibrotic and cardiomyocyte protective effects in the heart in an ERBB4-dependent manner, both in vitro and in vivo. This could be the start for the further development of small-molecule ERBB4 agonists as a novel class of drugs to treat heart failure. Cardiomyocyte-protective effect in vitroAnti-fibrotic effect in vivo

Fibroblast-specific deletion of ERBB4 impairs cardiac regeneration in neonatal mice

Abstract Background Scarless regeneration of the neonatal mammalian heart is a remarkable but poorly understood process. Previous studies have shown that paracrine actions of neuregulin-1 (NRG1) are indispensable to stimulate cardiomyocyte proliferation in the injured neonatal heart, and are mediated by activation of the ERBB4 receptor. It remains unclear, however, whether NRG1 also contributes to other steps of neonatal cardiac regeneration, e.g. to the control of collagen synthesis by fibroblasts, hence contributing to scarless healing. Purpose To study temporal evolution of the infarct size during 21 days after myocardial infarction (MI) in neonatal fibroblast-specific Erbb4 knock-out (KO) and wild type (WT) mice. We hypothesized that scarless healing would be completed within 21 days in WT mice, and incomplete in KO mice. Methods Fibroblast-specific hemizygous Erbb4 KO (FB-Erbb4-KO) mice were generated (Erbb4F/+ Col1a2-Cre+, C57BL/6 background), because fibroblast-specific nullizygous Erbb4 KO were not viable. Validation of the KO was performed both on RNA (qPCR) and protein (western blot) level. MI was induced in one-day old FB-Erbb4-KO and WT littermates of both sexes by permanent ligation of the left anterior descending (LAD) coronary artery under hypothermic anaesthesia. Pups from both groups were euthanized at 4 (WT, n=9; KO, n=11), 7 (WT, n=12; KO, n=4), 10 (WT, n=11; KO, n=7) and 21 (WT, n=16; KO, n=8) days post-MI. Following dissection, hearts were formalin-fixed and paraffin embedded for histopathological evaluation. Transverse sections were cut at 4 distinct locations from the ligation site to the apex and stained with Masson’s Trichrome for infarct scar measurement. Genotyping was performed post-mortem and unblinded after data analysis. Results Both the transgenic mice model and the LAD ligation technique were successfully validated. No significant differences in the initial infarct scar size were observed between WT and FB-Erbb4-KO mice 4 days post-MI (p=0.6556). 7-days post-MI the infarct scar size was 6-fold smaller compared to 4 days post-MI in both FB-Erbb4-KO and WT mice, with a trend towards a larger infarct scar size in the FB-Erbb4-KO group compared to WT (p=0.0989). At day 10 post-MI, infarct scar size in the FB-Erbb4-KO group was significantly larger (p=0.0499) compared to WT. At 21 days post-MI, the infarct size had almost completely disappeared in the WT group, but remained clearly present in the FB-Erbb4-KO group (Fig. 1, p=0.0099). Infarct scar sizes at all timepoints are graphically shown in Fig. 2. Conclusion Fibroblast-specific deletion of the ERBB4 receptor causes incomplete resolution of the infarct scar in murine neonates 21 days after MI. While the initial infarct scar size 4 days after injury is the same, impaired scar resolution becomes progressively more evident towards day 21 post-MI. These findings indicate that scarless healing of the neonatal mammalian heart requires NRG1/ERBB4 signalling in fibroblasts.Fig. 1Fig. 2

ERBB4 activation prevents microvascular dysfunction in a large animal model of hypertensive heart disease

Abstract Background Coronary microvascular dysfunction (CMD) participates in the pathophysiology of multiple cardiovascular diseases, but treatment options are limited. A new treatment option may include ERBB4 stimulation by neuregulin-1 (NRG1), which has anti-inflammatory, antifibrotic, and cardioprotective effects in models of heart failure. Objectives To assess the effect NRG1/ERBB4 stimulation on CMD in hypertensive heart disease. Methods Hypertensive heart disease was induced in 12 Aachener minipigs by implantation of deoxycorticosterone acetate (DOCA) pellets for 8 weeks and compared to 6 controls. The DOCA pigs were randomized to a weekly infusion of JK07, a NRG1 fusion protein with improved pharmacokinetic and pharmacodynamic properties, or vehicle. Microvascular resistance was measured using the bolus thermodilution method. Results DOCA significantly increased microvascular resistance compared to controls (from 14.5 to 19.9 mmHg.s, p = 0.028). This increase was abrogated by JK07 (11.3 mmHg.s, p = 0.018 vs DOCA). dP/dtmax increased by DOCA compared to controls (from 2415.5 to 4455.5 mmHg/s, p = 0.011), which was also abrogated by JK07 (3107.3 mmHg/s, p = 0.055 vs DOCA). Interstitial left ventricular fibrosis was significantly lower in JK07-treated pigs compared to DOCA only (2.1 vs. 5.4 %, p = 0.026), but without difference in perivascular fibrosis (p = 0.48). JK07 did not affect myocyte cross-sectional area, capillary density, pericyte coverage, or microvascular vessel thickness. Conclusions ERBB4 activation by JK07 is capable to prevent CMD in a DOCA hypertensive pig model. Functional rather than structural alterations may explain the protective effects of JK07 on microvascular resistance.Visual summaryJK07 decreases microvascular resistance

Cognitive Impairments Related to COMT and Neuregulin 1 Phenotypes as Transdiagnostic Markers in Schizophrenia Spectrum Patients

Background: Research on the interaction between antipsychotic treatment and cognitive dysfunction in schizophrenia spectrum disorders (SSDs) is extensive, yet the role of genetic polymorphisms in catechol-O-methyltransferase (COMT) and neuregulin 1 (NRG1) remains underexplored. Methods: This study evaluates the impact of COMT (rs4680) and NRG1 (rs3924999 and rs35753505) polymorphisms on cognitive functions in SSD patients. A cross-sectional study was conducted with fifty-four patients, assessed using the Positive and Negative Syndrome Scale (PANSS) and the CNS Vital Signs battery. Results: Significant cognitive function differences were observed across SSD diagnostic categories (p < 0.001). The NRG1 rs35753505 TT genotype was significantly associated with better verbal memory performance compared to the CC genotype (p = 0.03), while no significant differences were observed for other genotypes. The NRG1 rs3924999 AA genotype showed superior reasoning performance compared to AG and GG genotypes (p = 0.01), with AG and GG associated with lower scores (p = 0.01 and p = 0.02, respectively). Additionally, the COMT Val158Met genotype significantly influenced processing speed, with patients at the first episode of psychosis showing higher scores than chronic patients (p = 0.01). Conclusions: These findings suggest that NRG1 and COMT polymorphisms may influence cognitive domains in schizophrenia spectrum disorders, potentially informing personalized treatment and cognitive rehabilitation strategies.

Denervation‑induced NRG3 aggravates muscle heterotopic ossification via the ErbB4/PI3K/Akt signaling pathway.

Peripheral nerve injury exacerbates progression of muscle heterotopic ossification (HO) and induces changes in expression of local cytokines in muscle tissue. The objective of the present study was to assess the impact of peripheral nerve injury on muscle HO development and the mechanism of cytokine modulation. A mouse model of gastrocnemius muscle HO was established and the sciatic nerve cut to simulate peripheral nerve injury. To evaluate the underlying factors contributing to the exacerbation of muscle HO resulting from denervation, fresh muscle tissue was collected and micro‑computed tomography, histochemical staining, RNA‑sequencing, reverse transcription‑quantitative PCR, Western blot, muscle tissue chip array were performed to analyze the molecular mechanisms. Sciatic nerve injury exacerbated HO in the gastrocnemius muscle of mice. Moreover the osteogenic differentiation of nerve‑injured muscle tissue‑derived fibro‑adipogenic progenitors (FAPs) increased in vitro. The expression of neuregulin 3 (NRG3) was demonstrated to be increased after nerve injury by muscle tissue chip array. Subsequent transcriptome sequencing analysis of muscle tissue revealed an enrichment of the PI3K/Akt pathway following nerve injury and an inhibitor of the PI3K/Akt pathway reduced the osteogenic differentiation of FAPs. Mechanistically, in vitro, peripheral nerve injury increased secretion of NRG3, which, following binding to ErbB4 on the cell surface of FAPs, promoted expression of osteogenesis‑associated genes via the PI3K/Akt signaling pathway, thus contributing to osteogenic differentiation of FAPs. In vivo, inhibition of the PI3K/Akt pathway effectively protected against muscle HO induced by peripheral nerve injury in mice. The present study demonstrated that the regulatory roles of NRG3 and the PI3K/Akt pathway in peripheral nerve injury exacerbated muscle HO and highlights a potential therapeutic intervention for treatment of peripheral nerve injury‑induced muscle HO.

The role and mechanism of NRG1/ErbB4 in inducing the differentiation of induced pluripotent stem cells into cardiomyocytes

BackgroundWe aimed to investigate the effect and potential mechanism of enhancing Neuregulin1 (NRG1)/v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ErbB4) expression on the differentiation of induced pluripotent stem cells (iPSCs) into cardiomyocytes.MethodsWe utilized CRISPR-CAS9 technology to knock in ErbB4 and obtained a single-cell clone IPSN-AAVS1-CMV-ErbB4 (iPSCs-ErbB4). Subsequently, we induced the differentiation of iPSCs into cardiomyocytes and quantified the number of beating embryoid bodies. Furthermore, quantitative real-time PCR assessed the expression of cardiomyocyte markers, including ANP (atrial natriuretic peptide), Nkx2.5 (NK2 transcription factor related locus 5), and GATA4 (GATA binding protein 4). On the 14th day of differentiation, we observed the α-MHC (α-myosin heavy chain)-positive area using immunofluorescent staining and conducted western blotting to detect the expression of cTnT (cardiac troponin) protein and PI3K/Akt signaling pathway-related proteins. Additionally, we intervened the iPSCs-ErbB4 + NRG1 group with the PI3K/Akt inhibitor LY294002 and observed alterations in the expression of cardiomyocyte differentiation-related genes.ResultsThe number of beating embryoid bodies increased after promoting the expression of NRG1/ErbB4 compared to the iPSCs control group. Cardiomyocyte markers ANP, Nkx2.5, and GATA4 significantly increased on day 14 of differentiation, and the positive area of α-MHC was three times that of the iPSCs control group. Moreover, there was a marked increase in cTnT protein expression. However, there was no significant difference in cardiomyocyte differentiation between the iPSCs-ErbB4 group and the iPSCs control group. Akt phosphorylation was significantly increased in the iPSCs-ErbB4 + NRG1 group. LY294002 significantly reversed the enhancing effect of NRG1/ErbB4 overexpression on Akt phosphorylation as well as the increase in α-MHC and cTnT expression.ConclusionsIn conclusion, promoting the expression of NRG1/ErbB4 induced the differentiation of iPSC into cardiomyocytes, possibly through modulation of the PI3K/Akt signaling pathway.

The influence of the NRG1/ERBB4 signaling pathway on pulmonary artery endothelial cells.

This study aimed to examine the influence of the Neuregulin-1 (NRG1)/ERBB4 signaling pathway on the function of human pulmonary artery endothelial cells (HPAECs) and investigate the underlying mechanisms. Enzyme-linked immunosorbent assay indicated that ERBB4 levels in the serum of patients with pulmonary embolism (PE) were significantly higher than those of healthy controls (p < 0.05). In cellular studies, thrombin stimulation for 6 h led to a significant decrease in cell viability and overexpression of ERBB4 compared to control (p < 0.05). In the NRG1 group, apoptosis of HPAECs was reduced (p < 0.05), accompanied by a decrease in ERBB4 expression and an increase in p-ERBB4, phosphorylated serine/threonine kinase proteins (Akt) (p-Akt), and p-phosphoinositide 3-kinase (PI3K) expression (p < 0.05). In the AG1478 group, there was a significant increase in HPAEC apoptosis and a significant decrease in p-ERBB4 and ERBB4 expression compared to the Con group (p < 0.05). In the AG1478 + NRG1 group, there was an increase in the apoptosis rate and a significant decrease in the expression of p-ERBB4, ERBB4, p-Akt, and phosphorylated PI3K compared to the NRG1 group (p < 0.05). In animal studies, the PE group showed an increase in the expression of ERBB4 and p-ERBB4 compared to the Con group (p < 0.05). NRG1 treatment led to a significant reduction in embolism severity with decreased ERBB4 expression and increased p-ERBB4 expression (p < 0.05). Gene set enrichment analysis identified five pathways that were significantly associated with high ERBB4 expression, including CHOLESTEROL HOMEOSTASIS, OXIDATIVE PHOSPHORYLATION, and FATTY ACID METABOLISM (p < 0.05). Therefore, NRG1 inhibits apoptosis of HPAECs, accompanied by a decrease in ERBB4 and an increase in p-ERBB4. NRG1 inhibition in HPAECs apoptosis can be partially reversed by inhibiting ERBB4 expression with AG1478. ERBB4 has the potential to be a novel biological marker of PE.

NRG1 Fusions in NSCLC: Being eNRGy Conscious.

Fusions in neuregulin 1 (NRG1) are rare oncogenic drivers that occur across a number of tumor types, including non-small cell lung cancer (NSCLC). NRG1 has an EGF-like domain that serves as a ligand for HER3 receptors, inducing heterodimerization, usually with HER2, and subsequent activation of oncogenic downstream signaling pathways. Emerging evidence suggests that NSCLC harboring NRG1 fusions do not respond as well to standard therapeutic options including chemotherapy and immunotherapy, and prognosis is poor. Novel treatment approaches targeting the HER2/HER3 pathway are under investigation. Here, we discuss the biology and detection of NRG1 fusions in NSCLC and promising targeted treatment strategies for tumors harboring the mutation.

Regionalized cell and gene signatures govern esophageal epithelial homeostasis.

Regionalized disease prevalence is a common feature of the gastrointestinal tract. Herein, we employed regionally resolved Smart-seq3 single-cell sequencing, generating a comprehensive cell atlas of the adult mouse esophagus. Characterizing the esophageal axis, we identify non-uniform distribution of epithelial basal cells, fibroblasts, and immune cells. In addition, we demonstrate a position-dependent, but cell subpopulation-independent, transcriptional signature, collectively generating a regionalized esophageal landscape. Combining invivo models with organoid co-cultures, we demonstrate that proximal and distal basal progenitor cell states are functionally distinct. We find that proximal fibroblasts are more permissive for organoid growth compared with distal fibroblasts and that the immune cell profile is regionalized in two dimensions, where proximal-distal and epithelial-stromal gradients impact epithelial maintenance. Finally, we predict and verify how WNT, BMP, insulin growth factor (IGF), and neuregulin (NRG) signaling are differentially engaged along the esophageal axis. We establish a cellular and transcriptional framework for understanding esophageal regionalization, providing a functional basis for epithelial disease susceptibility.

Neuregulin 1 Signaling Attenuates Tumor Necrosis Factor α-Induced Female Rat Luteal Cell Death.

The corpus luteum (CL) is a transient ovarian endocrine structure that maintains pregnancy in primates during the first trimester and in rodents during the entire pregnancy by producing steroid hormone progesterone (P4). CL lifespan, growth, and differentiation are tightly regulated by survival and cell death signals through luteotrophic and luteolytic factors, including the epidermal growth factor (EGF)-like factor family. Neuregulin 1 (NRG1), a member of the EGF family, mediates its effect through ErbB2/3 receptors. However, the functional role of NRG1 in luteal cells (LCs) is unknown. Thus, this study investigated the role of NRG1 and its molecular mechanism of action in rat LC. Our experimental results suggest a strong positive correlation between steroidogenic acute regulatory protein (StAR) and NRG1 expression in mid-CL and serum P4 and estrogen (E2) production. In contrast, there was a decrease in StAR and NRG1 expression and P4 and E2 production with an increase in tumor necrosis factor α (TNFα) expression in regressing CL. Further in vitro studies in LCs showed that the knockdown of endogenous Nrg1 promoted the expression of proinflammatory and proapoptotic factors and decreased prosurvival factor expression. Subsequently, treatment with exogenous TNFα under these experimental conditions profoundly elevated proinflammatory and proapoptotic factors. Further analysis demonstrated that the phosphorylation status of ErbB2/3, PI3K, Ak strain transforming or protein kinase B (Akt), and ErK1/2 was significantly inhibited under these experimental conditions, whereas the treatment of TNFα further inhibited the phosphorylation of ErbB2/3, PI3K, Akt, and ErK1/2. Collectively, these studies provide new insights into the NRG1-mediated immunomodulatory and prosurvival role in LCs, which may maintain the function of CL.

Neuregulin 1 (NRG1) and its receptors in the enteric nervous system and other parts of the gastrointestinal wall.

Neuregulin 1 (NRG1) belonging to the transmembrane growth factors family is widespread in living organisms. It acts through ErbB family receptors and first of all takes part in embryogenesis, as well as in developmental, regenerative and adaptive processes occurring in various internal organs and systems. It is known that NRG1 and its receptors are present in various parts of the gastrointestinal (GI) tract. First of all NRG1 and ErbB receptors have been detected in the enteric nervous system (ENS) localized in the wall of the esophagus, stomach and intestine and regulating the majority of the GI tract functions, but also in the mucosal and muscular layers of the GI tract. The NRG1/ErbB pathway is involved in the development and differentiation of the ENS and regulation of the intestinal epithelium functions. Moreover, dysregulation of this pathway results in a wide range of gastrointestinal diseases. However, till now there are no summarizations of previous studies concerning distribution and functions of NRG1 and its receptors in the GI tract. The present review fills this gap.

Discovery of NRG1-VII: the myeloid-derived class of NRG1

The growth factor Neuregulin-1 (NRG1) has pleiotropic roles in proliferation and differentiation of the stem cell niche in different tissues. It has been implicated in gut, brain and muscle development and repair. Six isoform classes of NRG1 and over 28 protein isoforms have been previously described. Here we report a new class of NRG1, designated NRG1-VII to denote that these NRG1 isoforms arise from a myeloid-specific transcriptional start site (TSS) previously uncharacterized. Long-read sequencing was used to identify eight high-confidence NRG1-VII transcripts. These transcripts presented major structural differences from one another, through the use of cassette exons and alternative stop codons. Expression of NRG1-VII was confirmed in primary human monocytes and tissue resident macrophages and induced pluripotent stem cell-derived macrophages (iPSC-derived macrophages). Isoform switching via cassette exon usage and alternate polyadenylation was apparent during monocyte maturation and macrophage differentiation. NRG1-VII is the major class expressed by the myeloid lineage, including tissue-resident macrophages. Analysis of public gene expression data indicates that monocytes and macrophages are a primary source of NRG1. The size and structure of class VII isoforms suggests that they may be more diffusible through tissues than other NRG1 classes. However, the specific roles of class VII variants in tissue homeostasis and repair have not yet been determined.

NRG1 Gene Fusions-What Promise Remains Behind These Rare Genetic Alterations? A Comprehensive Review of Biology, Diagnostic Approaches, and Clinical Implications.

Non-small cell lung cancer (NSCLC) presents a variety of druggable genetic alterations that revolutionized the treatment approaches. However, identifying new alterations may broaden the group of patients benefitting from such novel treatment options. Recently, the interest focused on the neuregulin-1 gene (NRG1), whose fusions may have become a potential predictive factor. To date, the occurrence of NRG1 fusions has been considered a negative prognostic marker in NSCLC treatment; however, many premises remain behind the targetability of signaling pathways affected by the NRG1 gene. The role of NRG1 fusions in ErbB-mediated cell proliferation especially seems to be considered as a main target of treatment. Hence, NSCLC patients harboring NRG1 fusions may benefit from targeted therapies such as pan-HER family inhibitors, which have shown efficacy in previous studies in various cancers, and anti-HER monoclonal antibodies. Considering the increased interest in the NRG1 gene as a potential clinical target, in the following review, we highlight its biology, as well as the potential clinical implications that were evaluated in clinics or remained under consideration in clinical trials.

Genome-wide association reveals a locus in neuregulin 3 associated with gabapentin efficacy in women with chronic pelvic pain.

Chronic pelvic pain (CPP) in women with no obvious pelvic pathology has few evidence-based treatment options. Our recent multicenter randomized controlled trial (GaPP2) in women with CPP and no obvious pelvic pathology showed that gabapentin did not relieve pain overall and was associated with more side effects than placebo. We conducted an exploratory genome-wide association study using eligible GaPP2 participants aiming to identify genetic variants associated with gabapentin response. One genome-wide significant association with gabapentin analgesic response was identified, rs4442490, an intron variant located in Neuregulin 3 (NRG3) (p= 2·11×10-8; OR= 18·82 (95% CI 4·86-72·83). Analysis of a large sample of UK Biobank participants demonstrated phenome-wide significant brain imaging features of rs4442490, particularly implicating the orbitofrontal cortex. NRG3 is expressed predominantly in central nervous system tissues and plays a critical role in nervous system development, maintenance, and repair, suggesting a neurobiologically plausible role in gabapentin efficacy and potential for personalized analgesic treatment.

Circular RNA RRM2 alleviates metabolic dysfunction-associated steatotic liver disease by targeting miR-142-5p to increase NRG1 expression.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent chronic liver condition worldwide, demanding further investigation into its pathogenesis. Circular RNAs (circRNAs) are emerging as pivotal regulators in MASLD processes, yet their pathological implications in MASLD remain poorly understood. This study focused on elucidating the role of circular RNA ribonucleotide reductase subunit M2 (circRRM2) in MASLD progression. In this study, we used both in vitro and in vivo MASLD models using long-chain-free fatty acid (FFA)-treated hepatocytes and high-fat diet (HFD)-induced MASLD in mice, respectively. We determined the expression patterns of circRRM2, microRNA-142-5p (miR-142-5p), and neuregulin 1 (NRG1) in livers of MASLD-afflicted mice and MASLD hepatocytes by RT-qPCR. Dual-luciferase reporter assays verified the binding relationships among circRRM2, miR-142-5p, and NRG1. We conducted further analyses of their roles in MASLD hepatocytes and modulated circRRM2, miR-142-5p, and NRG1 expression in vitro by transfection. Our findings were validated in vivo. The results demonstrated reduced levels of circRRM2 and NRG1, along with elevated miR-142-5p expression in MASLD livers and hepatocytes. Overexpression of circRRM2 downregulated lipogenesis-related genes and decreased triglycerides accumulation in livers of MASLD mice. MiR-142-5p, which interacts with circRRM2, effectively counteracted the effects of circRRM2 in MASLD hepatocytes. Furthermore, NRG1 was identified as a miR-142-5p target, and its overexpression mitigated the regulatory impact of miR-142-5p on MASLD hepatocytes. In conclusion, circRRM2, via its role as a miR-142-5p sponge, upregulating NRG1, possibly influenced triglycerides accumulation in both in vitro and in vivo MASLD models.NEW & NOTEWORTHY CircRRM2 expression was downregulated in free fatty acid (FFA)-challenged hepatocytes and high-fat diet (HFD) fed mice. Overexpressed circular RNA ribonucleotide reductase subunit M2 (circRRM2) attenuated metabolic dysfunction-associated steatotic liver disease (MASLD) development by suppressing FFA-induced triglycerides accumulation. CircRRM2 targeted microRNA-142-5p (miR-142-5p), which served as an upstream inhibitor of neuregulin 1 (NRG1) and collaboratively regulated MASLD progression.

ErbB4 deficiency exacerbates olfactory dysfunction in an early-stage Alzheimer's disease mouse model.

Olfactory dysfunction is increasingly recognized as an early indicator of Alzheimer's disease (AD). Aberrations in GABAergic function and the excitatory/inhibitory (E/I) balance within the olfactory bulb (OB) have been implicated in olfactory impairment during the initial stages of AD. While the neuregulin 1 (NRG1)/ErbB4 signaling pathway is known to regulate GABAergic transmission in the brain and is associated with various neuropsychiatric disorders, its specific role in early AD-related olfactory impairment remains incompletely understood. This study demonstrated that olfactory dysfunction preceded cognitive decline in young adult APP/PS1 mice and was characterized by reduced levels of NRG1 and ErbB4 in the OB. Further investigation revealed that deletion of ErbB4 in parvalbumin interneurons reduced GABAergic transmission and increased hyperexcitability in mitral and tufted cells (M/Ts) in the OB, thereby accelerating olfactory dysfunction in young adult APP/PS1 mice. Additionally, ErbB4 deficiency was associated with increased accumulation of Aβ and BACE1-mediated cleavage of APP, along with enhanced CDK5 signaling in the OB. NRG1 infusion into the OB was found to enhance GABAergic transmission in M/Ts and alleviate olfactory dysfunction in young adult APP/PS1 mice. These findings underscore the critical role of NRG1/ErbB4 signaling in regulating GABAergic transmission and E/I balance within the OB, contributing to olfactory impairment in young adult APP/PS1 mice, and provide novel insights for early intervention strategies in AD. This work has shown that ErbB4 deficiency increased the burden of Aβ, impaired GABAergic transmission, and disrupted the E/I balance of mitral and tufted cells (M/Ts) in the OB, ultimately resulting in olfactory dysfunction in young adult APP/PS1 mice. NRG1 could enhance GABAergic transmission, rescue E/I imbalance in M/Ts, and alleviate olfactory dysfunction in young adult APP/PS1 mice. OB: olfactory bulb, E/I: excitation/inhibition, Pr: probability of release, PV: parvalbumin interneurons, Aβ: β-amyloid, GABA: gamma-aminobutyric acid.

Disrupted neuregulin 1-ErbB4 signaling: Consequences of prenatal morphine exposure in rat pups and molecular gateway to neurological impairment

ObjectiveMorphine exposure during pregnancy has detrimental effects on both the mother and her offspring, both during and after childbirth. This study aimed to investigate the impact of prenatal morphine exposure on rat pups and dams, specifically focusing on changes in Neuregulin-1 (Nrg-1)/ErbB4 gene expression, inflammation, and brain-derived neurotrophic factor (BDNF) levels. Materials and methodsTwenty female rats were randomized into two experimental groups:1-Morphine Group: Dams received morphine throughout pregnancy. 2-Control Group: Dams received no interventions.At the end of gestation, blood samples were collected from the dams. Subsequently, dams and their pups underwent tissue collection from the cortical area of the brain to evaluate the following parameters: Interleukin-6 (IL-6), Interleukin-10 (IL-10), total antioxidant capacity (TAC), Malondialdehyde (MDA), and Brain-derived neurotrophic factor (BDNF).Additionally, RNA was extracted from the pup's cortical brain tissue for the assessment of gene expression levels of Neuregulin-1 (NRG-1) and ErbB-4 using quantitative real-time polymerase chain reaction (qrt-PCR). ResultsThe molecular investigation revealed a decrease in NRG-1 and ErbB-4 expressions in the brain cortex of offspring exposed to morphine during prenatal development. Additionally, the levels of IL-6 and IL-10 in both the serum and brain of both the mothers and their offspring in the morphine group were significantly higher compared to the control group. The morphine-exposed group also exhibited significantly lower levels of TAC and higher levels of MDA, indicating increased oxidative stress. Furthermore, the levels of BDNF in the morphine group were significantly lower compared to the control group. ConclusionPrenatal morphine exposure in rats has detrimental effects on both the dams and their offspring. This study demonstrates that prenatal morphine exposure disrupts critical molecular pathways involved in neurodevelopment, inflammation, oxidative stress, and neurotrophic signaling. These findings suggest that prenatal morphine exposure can have long-lasting consequences for the offspring, potentially contributing to neurodevelopmental disorders and other health issues later in life.

Immobilized NRG1 Accelerates Neural Crest like Cell Differentiation Toward Functional Schwann Cells Through Sustained Erk1/2 Activation and YAP/TAZ Nuclear Translocation.

Neural Crest cells (NC) are a multipotent cell population that give rise to a multitude of cell types including Schwann cells (SC) in the peripheral nervous system (PNS). Immature SC interact with neuronal axons via the neuregulin 1 (NRG1) ligand present on the neuronal surface and ultimately form the myelin sheath. Multiple attempts to derive functional SC from pluripotent stem cells have met challenges with respect to expression of mature markers and axonal sorting. Here, they hypothesized that sustained signaling from immobilized NRG1 (iNRG1) might enhance the differentiation of NC derived from glabrous neonatal epidermis towards a SC phenotype. Using this strategy, NC derived SC expressed mature markers to similar levels as compared to explanted rat sciatic SC. Signaling studies revealed that sustained NRG1 signaling led to yes-associated protein 1 (YAP) activation and nuclear translocation. Furthermore, NC derived SC on iNRG1 exhibited mature SC function as they aligned with rat dorsal root ganglia (DRG) neurons in an in vitro coculture model; and most notably, aligned on neuronal axons upon implantation in a chick embryo model in vivo. Taken together their work demonstrated the importance of signaling dynamics in SC differentiation, aiming towards development of drug testing platforms for de-myelinating disorders.

Retracing RAS signaling by correlating protein expression in different subtypes of neurofibromatosis 1-associated nerve sheath tumors.

Expression patterns of key proteins involved in RAS signaling and connected pathways were determined and correlated to possibly provide information for therapeutic application of RAS inhibitors in neurofibromatosis type 1 (NF1)-associated peripheral nerve sheath tumors (PNST). Clinical variables (age, sex), histological parameters (cell density, mitoses), and expression of immunohistochemically evaluated ligand and receptor proteins (neuregulin 1 (NRG1), ErbB2, ErbB3), RAS pathway proteins (mTor, Rho, phosphorylated MEK), transcription factors (Pax7, Sox9), and proliferation marker Ki-67, were correlated in cutaneous (CNF, n = 136), diffuse (DNF, n = 123)/diffuse plexiform (DPNF, n = 113), and plexiform neurofibroma (PNF, n = 126), and in malignant PNST (MPNST, n = 22). In CNF, NRG1 correlated with Ki-67 and Pax7. Further, mTOR correlated with ErbB3, Sox9, Pax7, and Ki-67. In DNF/DPNF, expression of NRG1 correlated with pMEK and Pax7. mTOR correlated with pMEK, Sox9, and Pax7. Noteworthy, pMEK was weakly expressed in some DNF but not in DPNF. ErbB3 correlated with mTor and Ki-67. Furthermore, Rho correlated with Pax7 and Ki-67. In PNF, ErbB3 expression was associated with Sox9, mTOR, pMEK, and Pax7 as well as mTOR with Sox9 and Pax7, Rho with pMEK and Pax7, and pMEK with Pax7 and Sox9. In MPNST, only few correlations were observed, ErbB2 correlated with Ki-67, and Rho with pMEK. Signaling networks of the RAS pathway could be retraced by correlation analysis of protein expression in subgroups of NF1 associated benign PNST. In regard to treatment of PNST, MEK inhibitors, which are presently evaluated for PNF, may possibly also be effective to some extent in DNF.