scholarly journals Dysregulation of Grainyhead-like 3 expression causes widespread developmental defects

2021 ◽  
Author(s):  
Zihao Deng ◽  
Tariq Butt ◽  
Benedicta D. Arhatari ◽  
Charbel Darido ◽  
Alana Auden ◽  
...  
Keyword(s):  
Wound Repair ◽  
Skin Barrier ◽  
Ct Scanning ◽  
Longitudinal Axis ◽  
Loss Of Function ◽  
Mammalian Development ◽  
Gene Encoding ◽  
Developmental Defects ◽  
Barrier Formation ◽  
Function Models

Abstract The gene encoding the transcription factor, Grainyhead-like 3 (Grhl3), plays critical roles in mammalian development and homeostasis, and these have been uncovered through analysis of loss-of-function models. Grhl3-null embryos exhibit a range of gross phenotypes including a shortened longitudinal axis, thoraco-lumbo-sacral spina bifida and soft-tissue syndactyly. Additional studies reveal that these embryos also exhibit a proliferation/differentiation imbalance in the epidermis. This manifests as a failure in skin barrier formation resulting in peri-natal lethality, and defective wound repair. Conditional inactivation of Grhl3 in the squamous epithelium of adult skin, head and neck tissues, and oesophagus reproduces this proliferation/differentiation imbalance and leads to squamous cell carcinomas. These observations establish GRHL3 as a critical tumour suppressor. Despite these extensive analyses of Grhl3 loss-of-function models, the consequences of gain-of-function of this gene have been difficult to achieve. We have redressed this issue through the generation of a novel mouse model that expresses Grhl3 from a transgene integrated in the Rosa26 locus on an endogenous Grhl3-null background. Expression of the transgene rescues both the neurulation and skin barrier defects of the knockout mice, allowing survival into adulthood. Despite this, the mice are not normal, exhibiting a range of phenotypes attributable to dysregulated Grhl3 expression. In mice homozygous for the transgene, we observe a severe Shaker-Waltzer phenotype associated with hearing impairment. Micro-CT scanning of the cochleae and the vestibular apparatus revealed profound structural alterations underlying these phenotypes. In addition, these mice exhibit other developmental anomalies including hair loss, digit defects and epidermal dysmorphogenesis. These findings indicate that diverse developmental processes display low tolerance to dysregulation of Grhl3.

scholarly journals Mechanistic Insights into Axenfeld–Rieger Syndrome from Zebrafish foxc1 and pitx2 Mutants

2021 ◽  
Vol 22 (18) ◽  
pp. 10001
Author(s):  
Curtis R. French
Keyword(s):  
Transcription Factors ◽  
Developmental Disorders ◽  
Anterior Segment ◽  
Therapeutic Interventions ◽  
Loss Of Function ◽  
Cardiovascular Malformations ◽  
Developmental Defects ◽  
Rieger Syndrome ◽  
Function Models ◽  
Shed Light

Axenfeld–Rieger syndrome (ARS) encompasses a group of developmental disorders that affect the anterior segment of the eye, as well as systemic developmental defects in some patients. Malformation of the ocular anterior segment often leads to secondary glaucoma, while some patients also present with cardiovascular malformations, craniofacial and dental abnormalities and additional periumbilical skin. Genes that encode two transcription factors, FOXC1 and PITX2, account for almost half of known cases, while the genetic lesions in the remaining cases remain unresolved. Given the genetic similarity between zebrafish and humans, as well as robust antisense inhibition and gene editing technologies available for use in these animals, loss of function zebrafish models for ARS have been created and shed light on the mechanism(s) whereby mutations in these two transcription factors cause such a wide array of developmental phenotypes. This review summarizes the published phenotypes in zebrafish foxc1 and pitx2 loss of function models and discusses possible mechanisms that may be used to target pharmaceutical development and therapeutic interventions.

Implications of Fibroblast Growth Factors (FGFs) in Cancer: From Prognostic to Therapeutic Applications

2019 ◽  
Vol 20 (8) ◽  
pp. 852-870
Author(s):  
Hassan Dianat-Moghadam ◽  
Ladan Teimoori-Toolabi
Keyword(s):  
Growth Factors ◽  
Wound Repair ◽  
Fibroblast Growth Factors ◽  
Predictive Biomarkers ◽  
Fibroblast Growth ◽  
Loss Of Function ◽  
Cellular Processes ◽  
Fgfr Signaling ◽  
Proliferation And Metastasis ◽  
Immense Potential

Fibroblast growth factors (FGFs) are pleiotropic molecules exerting autocrine, intracrine and paracrine functions via activating four tyrosine kinase FGF receptors (FGFR), which further trigger a variety of cellular processes including angiogenesis, evasion from apoptosis, bone formation, embryogenesis, wound repair and homeostasis. Four major mechanisms including angiogenesis, inflammation, cell proliferation, and metastasis are active in FGF/FGFR-driven tumors. Furthermore, gain-of-function or loss-of-function in FGFRs1-4 which is due to amplification, fusions, mutations, and changes in tumor–stromal cells interactions, is associated with the development and progression of cancer. Although, the developed small molecule or antibodies targeting FGFR signaling offer immense potential for cancer therapy, emergence of drug resistance, activation of compensatory pathways and systemic toxicity of modulators are bottlenecks in clinical application of anti-FGFRs. In this review, we present FGF/FGFR structure and the mechanisms of its function, as well as cross-talks with other nodes and/or signaling pathways. We describe deregulation of FGF/FGFR-related mechanisms in human disease and tumor progression leading to the presentation of emerging therapeutic approaches, resistance to FGFR targeting, and clinical potentials of individual FGF family in several human cancers. Additionally, the underlying biological mechanisms of FGF/FGFR signaling, besides several attempts to develop predictive biomarkers and combination therapies for different cancers have been explored.

scholarly journals Gain-of-function GABRB3 variants identified in vigabatrin-hypersensitive epileptic encephalopathies

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Nathan L Absalom ◽  
Vivian W Y Liao ◽  
Kavitha Kothur ◽  
Dinesh C Indurthi ◽  
Bruce Bennetts ◽  
...  
Keyword(s):  
De Novo ◽  
Drug Effects ◽  
Receptor Expression ◽  
Aminobutyric Acid ◽  
Loss Of Function ◽  
Molecular Phenotype ◽  
Gain Of Function ◽  
Gene Encoding ◽  
Epileptic Encephalopathies ◽  
Receptor Phenotype

Abstract Variants in the GABRB3 gene encoding the β3-subunit of the γ-aminobutyric acid type A ( receptor are associated with various developmental and epileptic encephalopathies. Typically, these variants cause a loss-of-function molecular phenotype whereby γ-aminobutyric acid has reduced inhibitory effectiveness leading to seizures. Drugs that potentiate inhibitory GABAergic activity, such as nitrazepam, phenobarbital or vigabatrin, are expected to compensate for this and thereby reduce seizure frequency. However, vigabatrin, a drug that inhibits γ-aminobutyric acid transaminase to increase tonic γ-aminobutyric acid currents, has mixed success in treating seizures in patients with GABRB3 variants: some patients experience seizure cessation, but there is hypersensitivity in some patients associated with hypotonia, sedation and respiratory suppression. A GABRB3 variant that responds well to vigabatrin involves a truncation variant (p.Arg194*) resulting in a clear loss-of-function. We hypothesized that patients with a hypersensitive response to vigabatrin may exhibit a different γ-aminobutyric acid A receptor phenotype. To test this hypothesis, we evaluated the phenotype of de novo variants in GABRB3 (p.Glu77Lys and p.Thr287Ile) associated with patients who are clinically hypersensitive to vigabatrin. We introduced the GABRB3 p.Glu77Lys and p.Thr287Ile variants into a concatenated synaptic and extrasynaptic γ-aminobutyric acid A receptor construct, to resemble the γ-aminobutyric acid A receptor expression by a patient heterozygous for the GABRB3 variant. The mRNA of these constructs was injected into Xenopus oocytes and activation properties of each receptor measured by two-electrode voltage clamp electrophysiology. Results showed an atypical gain-of-function molecular phenotype in the GABRB3 p.Glu77Lys and p.Thr287Ile variants characterized by increased potency of γ-aminobutyric acid A without change to the estimated maximum open channel probability, deactivation kinetics or absolute currents. Modelling of the activation properties of the receptors indicated that either variant caused increased chloride flux in response to low concentrations of γ-aminobutyric acid that mediate tonic currents. We therefore propose that the hypersensitivity reaction to vigabatrin is a result of GABRB3 variants that exacerbate GABAergic tonic currents and caution is required when prescribing vigabatrin. In contrast, drug strategies increasing tonic currents in loss-of-function variants are likely to be a safe and effective therapy. This study demonstrates that functional genomics can explain beneficial and adverse anti-epileptic drug effects, and propose that vigabatrin should be considered in patients with clear loss-of-function GABRB3 variants.

scholarly journals Brain mast cells link the immune system to anxiety-like behavior

2008 ◽  
Vol 105 (46) ◽  
pp. 18053-18057 ◽  
Author(s):  
Katherine M. Nautiyal ◽  
Ana C. Ribeiro ◽  
Donald W. Pfaff ◽  
Rae Silver
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Mast Cell Activation ◽  
Neural Systems ◽  
Loss Of Function ◽  
Littermate Control ◽  
Cytokines And Chemokines ◽  
Function Models ◽  
The Brain

Mast cells are resident in the brain and contain numerous mediators, including neurotransmitters, cytokines, and chemokines, that are released in response to a variety of natural and pharmacological triggers. The number of mast cells in the brain fluctuates with stress and various behavioral and endocrine states. These properties suggest that mast cells are poised to influence neural systems underlying behavior. Using genetic and pharmacological loss-of-function models we performed a behavioral screen for arousal responses including emotionality, locomotor, and sensory components. We found that mast cell deficient KitW−sh/W−sh (sash−/−) mice had a greater anxiety-like phenotype than WT and heterozygote littermate control animals in the open field arena and elevated plus maze. Second, we show that blockade of brain, but not peripheral, mast cell activation increased anxiety-like behavior. Taken together, the data implicate brain mast cells in the modulation of anxiety-like behavior and provide evidence for the behavioral importance of neuroimmune links.

scholarly journals mRNA Surveillance Complex PELOTA-HBS1 Regulates Phosphoinositide-Dependent Protein Kinase1 and Plant Growth

2021 ◽  
Author(s):  
Wei Kong ◽  
Shutang Tan ◽  
Qing Zhao ◽  
De-Li Lin ◽  
Zhi-Hong Xu ◽  
...  
Keyword(s):  
Quality Control ◽  
Messenger Rna ◽  
Loss Of Function ◽  
Yeast Saccharomyces Cerevisiae ◽  
Developmental Defects ◽  
Mrna Surveillance ◽  
Dna Insertion ◽  
Dependent Protein ◽  
Heterodimeric Complex ◽  
Severe Growth

Abstract The quality control system for messenger RNA (mRNA) is fundamental for cellular activities in eukaryotes. To elucidate the molecular mechanism of 3’-Phosphoinositide-Dependent Protein Kinase1 (PDK1), a master regulator that is essential throughout eukaryotic growth and development, we employed a forward genetic approach to screen for suppressors of the loss-of-function T-DNA insertion double mutant pdk1.1 pdk1.2 in Arabidopsis thaliana. Notably, the severe growth attenuation of pdk1.1 pdk1.2 was rescued by sop21 (suppressor of pdk1.1 pdk1.2), which harbours a loss-of-function mutation in PELOTA1 (PEL1). PEL1 is a homologue of mammalian PELOTA and yeast (Saccharomyces cerevisiae) DOM34p, which each form a heterodimeric complex with the GTPase HBS1 (HSP70 SUBFAMILY B SUPPRESSOR1, also called SUPERKILLER PROTEIN7, SKI7), a protein that is responsible for ribosomal rescue and thereby assures the quality and fidelity of mRNA molecules during translation. Genetic analysis further revealed that a dysfunctional PEL1-HBS1 complex failed to degrade the T-DNA-disrupted PDK1 transcripts, which were truncated but functional, and thus rescued the growth and developmental defects of pdk1.1 pdk1.2. Our studies demonstrated the functionality of a homologous PELOTA-HBS1 complex and identified its essential regulatory role in plants, providing insights into the mechanism of mRNA quality control.

scholarly journals Inner Ear and Muscle Developmental Defects in Smpx-Deficient Zebrafish Embryos

2021 ◽  
Vol 22 (12) ◽  
pp. 6497
Author(s):  
Anna Ghilardi ◽  
Alberto Diana ◽  
Renato Bacchetta ◽  
Nadia Santo ◽  
Miriam Ascagni ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Hair Cells ◽  
Muscle Fibers ◽  
Underlying Mechanism ◽  
Loss Of Function ◽  
Zebrafish Model ◽  
Developmental Defects ◽  
Inner Ear Development ◽  
Syndromic Hearing Loss

The last decade has witnessed the identification of several families affected by hereditary non-syndromic hearing loss (NSHL) caused by mutations in the SMPX gene and the loss of function has been suggested as the underlying mechanism. In the attempt to confirm this hypothesis we generated an Smpx-deficient zebrafish model, pointing out its crucial role in proper inner ear development. Indeed, a marked decrease in the number of kinocilia together with structural alterations of the stereocilia and the kinocilium itself in the hair cells of the inner ear were observed. We also report the impairment of the mechanotransduction by the hair cells, making SMPX a potential key player in the construction of the machinery necessary for sound detection. This wealth of evidence provides the first possible explanation for hearing loss in SMPX-mutated patients. Additionally, we observed a clear muscular phenotype consisting of the defective organization and functioning of muscle fibers, strongly suggesting a potential role for the protein in the development of muscle fibers. This piece of evidence highlights the need for more in-depth analyses in search for possible correlations between SMPX mutations and muscular disorders in humans, thus potentially turning this non-syndromic hearing loss-associated gene into the genetic cause of dysfunctions characterized by more than one symptom, making SMPX a novel syndromic gene.

scholarly journals Up-regulation of long non-coding RNA CYTOR induced by icariin promotes the viability and inhibits the apoptosis of chondrocytes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Guoyou Wang ◽  
Lei Zhang ◽  
Huarui Shen ◽  
Qi Hao ◽  
Shijie Fu ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Inflammatory Factors ◽  
Enzyme Linked Immunosorbent Assay ◽  
Protective Effects ◽  
Loss Of Function ◽  
Protective Function ◽  
Non Coding Rna ◽  
Effective Component ◽  
Short Hairpin Rnas ◽  
Function Models

Abstract Background Icariin (ICAR) is the main effective component extracted from epimedium, and is reported to have the potential to treat osteoarthritis (OA). However, its pharmacological function on chondrocytes has not been fully clarified. Methods Different doses of ICAR were used to treat chondrocyte cell lines, including CHON-001 and ATDC5. Then the expressions of different lncRNAs were measured by qRT-PCR. Interleukin-1β (IL-1β) was used to simulate the inflammatory response environment of chondrocytes. Overexpression plasmids and short hairpin RNAs of lncRNA CYTOR were used to construct gain-of-function and loss of function models. CCK-8 was conducted to determine the cell viability. Flow cytometry was used to detect the apoptosis of chondrocytes. Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the contents of inflammatory factors (IL-6, IL-8, TNF-α) in the supernatant of the chondrocytes. Results Compared with other lncRNAs, CYTOR was changed most significantly in both CHON-001 and ATDC5 cells after treatment with ICAR. ICAR promotes the viability and inhibits the apoptosis of CHON-001 and ATDC5 cells induced by IL-1β, accompanied with reduced levels of inflammatory factors. Overexpression of CYTOR facilitated the viability of chondrocytes, while repressed their apoptosis and inflammatory response. What’s more, knockdown of CYTOR reversed the protective effects of ICAR on chondrocytes. Conclusion CYTOR was a pivotal lncRNA involved in the protective function of ICAR on chondrocytes.

scholarly journals The Multifaceted Roles of MicroRNAs in Cystic Fibrosis

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1102
Author(s):  
Fatima Domenica Elisa De Palma ◽  
Valeria Raia ◽  
Guido Kroemer ◽  
Maria Chiara Maiuri
Keyword(s):  
Cystic Fibrosis ◽  
Respiratory Infections ◽  
Current Knowledge ◽  
Pancreatic Insufficiency ◽  
Clinical Manifestations ◽  
Predictive Biomarkers ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Multisystemic Disease

Cystic fibrosis (CF) is a lifelong disorder affecting 1 in 3500 live births worldwide. It is a monogenetic autosomal recessive disease caused by loss-of-function mutations in the gene encoding the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR), the impairment of which leads to ionic disequilibria in exocrine organs. This translates into a chronic multisystemic disease characterized by airway obstruction, respiratory infections, and pancreatic insufficiency as well as hepatobiliary and gastrointestinal dysfunction. Molecular characterization of the mutational heterogeneity of CFTR (affected by more than 2000 variants) improved the understanding and management of CF. However, these CFTR variants are linked to different clinical manifestations and phenotypes, and they affect response to treatments. Expanding evidence suggests that multisystemic disease affects CF pathology via impairing either CFTR or proteins regulated by CFTR. Thus, altering the expression of miRNAs in vivo could constitute an appealing strategy for developing new CF therapies. In this review, we will first describe the pathophysiology and clinical management of CF. Then, we will summarize the current knowledge on altered miRNAs in CF patients, with a focus on the miRNAs involved in the deregulation of CFTR and in the modulation of inflammation. We will highlight recent findings on the potential utility of measuring circulating miRNAs in CF as diagnostic, prognostic, and predictive biomarkers. Finally, we will provide an overview on potential miRNA-based therapeutic approaches.

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