Decreased circulating ErbB4 ectodomain fragments as a read-out of impaired signaling function in amyotrophic lateral sclerosis

Identification and characterization of novel ERBB4 variant associated with sporadic amyotrophic lateral sclerosis (ALS)

Amyotrophic Lateral Sclerosis (ALS) is the most common type of motor neuron disease characterized by progressive motor neuron degeneration in brain and spinal cord. Most cases are sporadic in ALS and 5-10% of cases are familiar. >50 genes are known to be associated with ALS and one of them is ERBB4. In this paper, we report the case of a 53-year-old ALS patient with progressive muscle weakness and fasciculation, but he had no cognitive decline. We performed the next generation sequencing (NGS) and in silico analysis, it predicted a highly pathogenic variant, c.2116 A > G, p.Asn706Asp (N706D) in the ERBB4 gene. The amino acid residue is highly conserved among species. ERBB4 is a member of the ERBB family of receptor tyrosine kinases. ERBB4 has multiple tyrosine phosphorylation sites, including an autophosphorylation site at tyrosine 1284 residue. Autophosphorylation of ERBB4 promotes biological activity and it associated with NRG-1/ERBB4 pathway. It is already known that tyrosine 128 phosphorylation of ERBB4 is decreased in patients who have ALS-associated ERBB4 mutations. We generated ERBB4 N706D construct using site-directed mutagenesis and checked the phosphorylation level of ERBB4 N706D in NSC-34 cells. We found that the phosphorylation of ERBB4 N706D was decreased compared to ERBB4 wild-type, indicating a loss of function mutation in ERBB4. We report a novel variant in ERBB4 gene leading to ALS through dysfunction of ERBB4.

Behavioral variant frontotemporal dementia associated with GRN and ErbB4 gene mutations: a case report and literature review

OBJECTIVE

To report the clinical manifestation and genetic characteristics of a patient having frontotemporal dementia (FTD) with abnormal behavior and unstable walking.

METHODS

The clinical and imaging features of a patient who was eventually diagnosed with FTD were analyzed. The patient's neuropsychological, PET-CT, electromyography, and genetic data were collected. Furthermore, the patient's blood samples were examined for FTD-related genes.

RESULTS

The patient was a 52-year-old man with hidden onset. The symptoms progressed gradually, presenting with abnormal behaviors, including repeated shopping, taking away other people's things, constantly eating snacks, and frequently calling friends at night. The patient also exhibited executive dysfunction, such as the inability to cook and multiple driving problems, e.g., constantly deviates from his lane while driving. In addition, the patient showed personality changes such as irritability, indifference, and withdrawal, as well as motor symptoms, including unstable walking and frequent falls when walking. Brain magnetic resonance imaging revealed hippocampal sclerosis along with widening and deepening of the bilateral temporal lobe sulcus. Brain metabolic imaging via PET-CT demonstrated decreased metabolism in the bilateral prefrontal lobe, with the abnormal energy metabolism indicating FTD. Lastly, blood sample analysis detected mutations in the amyotrophic lateral sclerosis (ALS)-related GRN gene c.1352C > T (p.P451L) and ErbB4 gene c.256 T > C (p.Y86H).

CONCLUSION

This is the first case of heterozygous mutations in the GRN and ErbB4 genes in FTD alone. The GRN and ErbB4 genes are likely to be important in the pathogenesis of FTD, expanding the common genetic profile of ALS and FTD.

Parvalbumin interneurons dysfunction is potentially associated with FαMNs decrease and NRG1-ErbB4 signaling inhibition in spinal cord in amyotrophic lateral sclerosis

OBJECTIVE

To investigate the alteration of PV interneurons in ALS mainly focusing its dynamic changes and its relationship with motor neurons and ErbB4 signaling.

METHODS

SOD1G93A mice were used as ALS model. ALS animals were divided into different groups according to birth age: symptomatic prophase (50~60 days), symptomatic phase (90~100 days), and symptomatic progression (130~140 days). Immunofluorescence was performed for measurement of PV-positive interneurons, MMP-9, ChAT, NeuN and ErbB4. RT-qPCR and western blot were used to determine the expression of PV and MMP-9.

RESULTS

PV expression was remarkably higher in the anterior horn of gray matter compared with posterior horn and area in the middle of gray matter in control mice. In ALS mice, PV, MMP-9 and ErbB4 levels were gradually decreased along with onset. PV, MMP-9 and ErbB4 levels in ALS mice were significantly down-regulated than control mice after onset, indicating the alteration of PV interneurons, FαMNs and ErbB4. SαMNs levels only decreased remarkably at symptomatic progression in ALS mice compared with control mice, while γMNs levels showed no significant change during whole period in all mice. MMP-9 and ErbB4 were positively correlated with PV. NRG1 treatment significantly enhanced the expression of ErBb4, PV and MMP-9 in ALS mice.

CONCLUSION

PV interneurons decrease is along with FαMNs and ErbB4 decrease in ALS mice.

Gene Therapy Overexpressing Neuregulin 1 Type I in Combination With Neuregulin 1 Type III Promotes Functional Improvement in the SOD1G93A ALS Mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting the neuromuscular system for which currently there is no effective therapy. Motoneuron (MN) degeneration involves several complex mechanisms, including surrounding glial cells and skeletal muscle contributions. Neuregulin 1 (NRG1) is a trophic factor present particularly in MNs and neuromuscular junctions. Our previous studies revealed that gene therapy overexpressing the isoform I (NRG1-I) in skeletal muscles as well as overexpressing the isoform III (NRG1-III) directly in the central nervous system are both effective in preserving MNs in the spinal cord of ALS mice, opening novel therapeutic approaches. In this study, we combined administration of both viral vectors overexpressing NRG1-I in skeletal muscles and NRG1-III in spinal cord of the SOD1^G93A mice in order to obtain a synergistic effect. The results showed that the combinatorial gene therapy increased preservation of MNs and of innervated neuromuscular junctions and reduced glial reactivity in the spinal cord of the treated SOD1^G93A mice. Moreover, NRG1 isoforms overexpression improved motor function of hindlimb muscles and delayed the onset of clinical disease. However, this combinatory gene therapy did not produce a synergic effect compared with single therapies, suggesting an overlap between NRG1-I and NRG1-III activated pathways and their beneficial effects.

Serum biomarkers associated with baseline clinical severity in young steroid-naïve Duchenne muscular dystrophy boys

Duchenne muscular dystrophy (DMD) is caused by loss of dystrophin in muscle, and while all patients share the primary gene and biochemical defect, there is considerable patient–patient variability in clinical symptoms. We sought to develop multivariate models of serum protein biomarkers that explained observed variation, using functional outcome measures as proxies for severity. Serum samples from 39 steroid-naïve DMD boys 4 to <7 years enrolled into a clinical trial of vamorolone were studied (NCT02760264). Four assessments of gross motor function were carried out for each participant over a 6-week interval, and their mean was used as response for biomarker models. Weighted correlation network analysis was used for unsupervised clustering of 1305 proteins quantified using SOMAscan^® aptamer profiling to define highly representative and connected proteins. Multivariate models of biomarkers were obtained for time to stand performance (strength phenotype; 17 proteins) and 6 min walk performance (endurance phenotype; 17 proteins) including some shared proteins. Identified proteins were tested with associations of mRNA expression with histological severity of muscle from dystrophinopathy patients (n = 28) and normal controls (n = 6). Strong associations predictive of both clinical and histological severity were found for ERBB4 (reductions in both blood and muscle with increasing severity), SOD1 (reductions in muscle and increases in blood with increasing severity) and CNTF (decreased levels in blood and muscle with increasing severity). We show that performance of DMD boys was effectively modeled with serum proteins, proximal strength associated with growth and remodeling pathways and muscle endurance centered on TGFβ and fibrosis pathways in muscle.

The Skeletal Muscle Emerges as a New Disease Target in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that leads to progressive degeneration of motor neurons (MNs) and severe muscle atrophy without effective treatment. Most research on ALS has been focused on the study of MNs and supporting cells of the central nervous system. Strikingly, the recent observations of pathological changes in muscle occurring before disease onset and independent from MN degeneration have bolstered the interest for the study of muscle tissue as a potential target for delivery of therapies for ALS. Skeletal muscle has just been described as a tissue with an important secretory function that is toxic to MNs in the context of ALS. Moreover, a fine-tuning balance between biosynthetic and atrophic pathways is necessary to induce myogenesis for muscle tissue repair. Compromising this response due to primary metabolic abnormalities in the muscle could trigger defective muscle regeneration and neuromuscular junction restoration, with deleterious consequences for MNs and thereby hastening the development of ALS. However, it remains puzzling how backward signaling from the muscle could impinge on MN death. This review provides a comprehensive analysis on the current state-of-the-art of the role of the skeletal muscle in ALS, highlighting its contribution to the neurodegeneration in ALS through backward-signaling processes as a newly uncovered mechanism for a peripheral etiopathogenesis of the disease.

Circular RNA circ_0001162 promotes cell proliferation and invasion of glioma via the miR-936/ERBB4 axis

The biological modulatory roles of many circular RNAs (circRNAs) have been validated in glioma. The current study was designed to research the functional mechanism of circ_0001162 in glioma progression. The quantitative real-time polymerase chain reaction (qRT-PCR) was used for assaying the levels of circ_0001162 and microRNA-936 (miR-936). Cell proliferation and colony formation abilities were evaluated via 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) and colony formation assay, respectively. Transwell assay was applied to assess cell migration and invasion. The impact of circ_0001162 on glioma growth in vivo was performed using xenograft tumor assay. The target binding was affirmed via the dual-luciferase reporter and RNA pull-down assays. All protein expression levels were examined via Western blot. Circ_0001162 was an overexpressed circRNA in glioma. Circ_0001162 promoted glioma cell proliferation, colony formation, migration and invasion in vitro. Tumorigenesis of glioma in vivo was also enhanced by circ_0001162. Circ_0001162 could directly target miR-936 and the biological function of circ_0001162 in glioma was related to the inhibition of miR-936. ErbB2 receptor tyrosine kinase 4 (ERBB4) was a direct target of miR-936. Additionally, miR-936 inhibited the glioma development via targeting ERBB4. The miR-936/ERBB4 axis was responsible for the oncogenic role of circ_0001162 in glioma. The effects of circ_0001162 on glioma cells were also associated with the positive regulation of ERBB4. These results indicated that circ_0001162 contributed to the glioma progression via regulating the miR-936/ERBB4 axis, which laid a foundation for the pathomechanism and molecular treatment of glioma.

The multifaceted role of kinases in amyotrophic lateral sclerosis: genetic, pathological and therapeutic implications

Amyotrophic lateral sclerosis is the most common degenerative disorder of motor neurons in adults. As there is no cure, thousands of individuals who are alive at present will succumb to the disease. In recent years, numerous causative genes and risk factors for amyotrophic lateral sclerosis have been identified. Several of the recently identified genes encode kinases. In addition, the hypothesis that (de)phosphorylation processes drive the disease process resulting in selective motor neuron degeneration in different disease variants has been postulated. We re-evaluate the evidence for this hypothesis based on recent findings and discuss the multiple roles of kinases in amyotrophic lateral sclerosis pathogenesis. We propose that kinases could represent promising therapeutic targets. Mainly due to the comprehensive regulation of kinases, however, a better understanding of the disturbances in the kinome network in amyotrophic lateral sclerosis is needed to properly target specific kinases in the clinic.

Therapeutic Role of Neuregulin 1 Type III in SOD1-Linked Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating motoneuron (Mn) disease without effective cure currently available. Death of MNs in ALS is preceded by failure of neuromuscular junctions and axonal retraction. Neuregulin 1 (NRG1) is a neurotrophic factor highly expressed in MNs and neuromuscular junctions that support axonal and neuromuscular development and maintenance. NRG1 and its ErbB receptors are involved in ALS. Reduced NRG1 expression has been found in ALS patients and in the ALS SOD1G93A mouse model; however, the expression of the isoforms of NRG1 and its receptors is still controversial. Due to the reduced levels of NRG1 type III (NRG1-III) in the spinal cord of ALS patients, we used gene therapy based on intrathecal administration of adeno-associated virus to overexpress NRG1-III in SOD1G93A mice. The mice were evaluated from 9 to 16 weeks of age by electrophysiology and rotarod tests. At 16 weeks, samples were harvested for histological and molecular analyses. Our results indicate that overexpression of NRG1-III is able to preserve neuromuscular function of the hindlimbs, improve locomotor performance, increase the number of surviving MNs, and reduce glial reactivity in the treated female SOD1G93A mice. Furthermore, the NRG1-III/ErbB4 axis appears to regulate MN excitability by modulating the chloride transporter KCC2 and reduces the expression of the MN vulnerability marker MMP-9. However, NRG1-III did not have a significant effect on male mice, indicating relevant sex differences. These findings indicate that increasing NRG1-III at the spinal cord is a promising approach for promoting MN protection and functional improvement in ALS.

Gene therapy for overexpressing Neuregulin 1 type I in skeletal muscles promotes functional improvement in the SOD1G93A ALS mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motoneurons (MNs), with no effective treatment currently available. The molecular mechanisms that are involved in MN death are complex and not fully understood, with partial contributions of surrounding glial cells and skeletal muscle to the disease. Neuregulin 1 (NRG1) is a trophic factor highly expressed in MNs and neuromuscular junctions. Recent studies have suggested a crucial role of the isoform I (NRG1-I) in the collateral reinnervation process in skeletal muscle, and NRG1-III in the preservation of MNs in the spinal cord, opening a window for developing novel therapies for neuromuscular diseases like ALS. In this study, we overexpressed NRG1-I widely in the skeletal muscles of the SOD1^G93A transgenic mouse. The results show that NRG1 gene therapy activated the survival pathways in muscle and spinal cord, increasing the number of surviving MNs and neuromuscular junctions and reducing the astroglial reactivity in the spinal cord of the treated SOD1^G93A mice. Furthermore, NRG1-I overexpression preserved motor function and delayed the onset of clinical disease. In summary, our data indicates that NRG1 plays an important role on MN survival and muscle innervation in ALS, and that viral-mediated overexpression of NRG1 isoforms may be considered as a promising approach for ALS treatment.