Hedgehog patterns midbrain ARChitecture

Sonic hedgehog signalling pathway contributes in age-related disorders and Alzheimer's disease

Alzheimer's disease (AD) is caused by the aging process and manifested by cognitive deficits and progressive memory loss. During aging, several conditions, including hypertension, diabetes, and cholesterol, have been identified as potential causes of AD by affecting Sonic hedgehog (Shh) signalling. In addition to being essential for cell differentiation and proliferation, Shh signalling is involved in tissue repair and the prevention of neurodegeneration. Neurogenesis is dependent on Shh signalling; inhibition of this pathway results in neurodegeneration. Several protein-protein interactions that are involved in Shh signalling are implicated in the pathophysiology of AD like overexpression of the protein nexin-1 inhibits the Shh pathway in AD. A protein called Growth Arrest Specific-1 works with another protein called cysteine dioxygenase (CDO) to boost Shh signalling. CDO is involved in the development of the central nervous system (CNS). Shh signalling strengthened the blood brain barrier and therefore prevent the entry of amyloid beta and other toxins to the brain from periphery. Further, several traditional remedies used for AD and dementia, including Epigallocatechin gallate, yokukansan, Lycium barbarum polysaccharides, salvianolic acid, and baicalin, are known to stimulate the Shh pathway. In this review, we elaborated that the Shh signalling exerts a substantial influence on the pathogenesis of AD. In this article, we have tried to explore the various possible connections between the Shh signalling and various known pathologies of AD.

Molecular mechanism of angiogenesis for cerebral infarction rats by acupuncture intervention based on sonic hedgehog signaling pathway

BACKGROUND

To study the factors of the Sonic Hedgehog (Shh) signaling pathway after permanent cerebral ischemic and the effects by acupuncture.

METHODS

Male Wistar rats were divided into Electro-acupuncture (EA) group, Model Control (MC) group, and blank control (Control) group. EA and MC were divided into 9 phases, namely 1 h, 3 h, 6 h, 9 h, 12 h, 24 h, 3 d, 7 d, and 12 d after the operation. The neurological deficits and permanent cerebral ischemic volume were observed. The immunofluorescence method was used to examine the angiogenesis. (Polymerase Chain Reaction) PCR and (Immunohistochemistry) IHC were used to test the changes in Shh, Ptch, Smo, and Gli2 mRNA and proteins.

RESULTS

The neurological severity scores (NSS) of the Control was 0, the score of the EA group was less than that of the MC. The cerebral permanent ischemic volume of the Control was 0 %, and the EA group's was smaller than that of the MC. The expression of copositive cells in the EA group was higher than the MC's from 12 h to 12 d, and the EA group had more peripheral blood vessels. The rat brain expressions of Shh, Ptch, Smo and Gli2 mRNA and proteins in the MC was higher than that of the Control, the rat brain expression of the EA group was higher than that of the MC.

CONCLUSIONS

EA can upregulate the expression of the Shh signaling pathway factors, thereby promoting angiogenesis.

Three Novel Variants of CEP290 and CC2D2DA and a Link Between ZNF77 and SHH Signaling Pathway Are Found in Two Meckel-Gruber Syndrome Fetuses

Meckel-Gruber syndrome (MKS) is a rare lethal autosomal recessive inherited disorder. Missed diagnosis might happen in clinical works due to an unclear genotype–phenotype correlation. We analyzed two families visiting our center; the parents are normal; each of the family aborted a fetus at 12WG. Following ultrasonography and pathological examination, both were diagnosed as MKS. Whole exome sequencing identified a compound heterozygous of two novel variants of CEP290 and a heterozygous of a novel variant of CC2D2A. Frameshift mutations in ZNF77 were also detected. Western blot analyzing whole-brain tissue showed that the expression of ZNF77, CC2D2A, and CEP290 was enhanced. HEK293T transfected with over-expression wildtype/mutated ZNF77 plasmid showed that SHH was increased in wildtype ZNF77 cells, while SHH and CC2D2A were increased in mutated ZNF77 cells. Our research provided two novel pathogenic variants of CEP290 and CC2D2A and suggested that ZNF77 might promote the expression of CC2D2A and regulate the amount of SHH.

Disruption of morphogenic and growth pathways in lysosomal storage diseases

The lysosome achieved a new protagonism that highlights its multiple cellular functions, such as in the catabolism of complex substrates, nutrient sensing, and signaling pathways implicated in cell metabolism and growth. Lysosomal storage diseases (LSDs) cause lysosomal accumulation of substrates and deficiency in trafficking of macromolecules. The substrate accumulation can impact one or several pathways which contribute to cell damage. Autophagy impairment and immune response are widely studied, but less attention is paid to morphogenic and growth pathways and its impact on the pathophysiology of LSDs. Hedgehog pathway is affected with abnormal expression and changes in distribution of protein levels, and a reduced number and length of primary cilia. Moreover, growth pathways are identified with delay in reactivation of mTOR that deregulate termination of autophagy and reformation of lysosomes. Insulin resistance caused by changes in lipids rafts has been described in different LSDs. While the genetic and biochemical bases of deficient proteins in LSDs are well understood, the secondary molecular mechanisms that disrupt wider biological processes associated with LSDs are only now becoming clearer. Therefore, we explored how specific signaling pathways can be related to specific LSDs, showing that a system medicine approach could be a valuable tool for the better understanding of LSD pathogenesis. This article is categorized under: Metabolic Diseases > Molecular and Cellular Physiology.

Primary Cilia-Related Pathways Moderate the Development and Therapy Resistance of Glioblastoma

As microtubule-based structures, primary cilia are typically present on the cells during the G0 or G1-S/G2 phase of the cell cycle and are closely related to the development of the central nervous system. The presence or absence of this special organelle may regulate the central nervous system tumorigenesis (e.g., glioblastoma) and several degenerative diseases. Additionally, the development of primary cilia can be regulated by several pathways. Conversely, primary cilia are able to regulate a few signaling transduction pathways. Therefore, development of the central nervous system tumors in conjunction with abnormal cilia can be regulated by up- or downregulation of the pathways related to cilia and ciliogenesis. Here, we review some pathways related to ciliogenesis and tumorigenesis, aiming to provide a potential target for developing new therapies at genetic and molecular levels.

The Role of Small Molecules and Their Effect on the Molecular Mechanisms of Early Retinal Organoid Development

Early in vivo embryonic retinal development is a well-documented and evolutionary conserved process. The specification towards eye development is temporally controlled by consecutive activation or inhibition of multiple key signaling pathways, such as the Wnt and hedgehog signaling pathways. Recently, with the use of retinal organoids, researchers aim to manipulate these pathways to achieve better human representative models for retinal development and disease. To achieve this, a plethora of different small molecules and signaling factors have been used at various time points and concentrations in retinal organoid differentiations, with varying success. Additions differ from protocol to protocol, but their usefulness or efficiency has not yet been systematically reviewed. Interestingly, many of these small molecules affect the same and/or multiple pathways, leading to reduced reproducibility and high variability between studies. In this review, we make an inventory of the key signaling pathways involved in early retinogenesis and their effect on the development of the early retina in vitro. Further, we provide a comprehensive overview of the small molecules and signaling factors that are added to retinal organoid differentiation protocols, documenting the molecular and functional effects of these additions. Lastly, we comparatively evaluate several of these factors using our established retinal organoid methodology.

Differential responses of larval zebrafish to the fungicide propamocarb: Endpoints at development, locomotor behavior and oxidative stress

The fungicide propamocarb (PM) is widely used to protect cucumbers, tomatoes and other plants from pathogens. According to previous studies, PM could be detected in the aquatic system in some area. However, the toxic effects of PM on zebrafish received very limited attention. In this study, we examined the toxic effects of various concentration of PM on the endpoints of development, locomotor behavior and oxidative stress in larval zebrafish. It was observed that PM exposure delayed embryonic development, inhibited hatchability at 60 and 72 h postfertilization and increased heart rate. After PM exposure, the larval zebrafish showed abnormal free swimming behavior and the swimming behavior in response to light-dark transition, indicating that PM had the potential to induce neurotoxicity. Moreover, PM exposure also affected the enzymatic activity of acetylcholinesterase and dopamine and the transcriptional level of genes related to neurotoxicity. In addition, PM exposure not only affects catalase (CAT), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activity but also affects the transcription level of various genes. We believed that PM induced oxidative stress was also a possible reason to cause neurotoxicity in larval zebrafish. In summary, our results suggested that PM could disturb the endpoints at development, locomotor behavior and oxidative stress in larval zebrafish.

Association of genes with phenotype in autism spectrum disorder

Autism spectrum disorder (ASD) is a genetic heterogeneous neurodevelopmental disorder that is characterized by impairments in social interaction and speech development and is accompanied by stereotypical behaviors such as body rocking, hand flapping, spinning objects, sniffing and restricted behaviors. The considerable significance of the genetics associated with autism has led to the identification of many risk genes for ASD used for the probing of ASD specificity and shared cognitive features over the past few decades. Identification of ASD risk genes helps to unravel various genetic variants and signaling pathways which are involved in ASD. This review highlights the role of ASD risk genes in gene transcription and translation regulation processes, as well as neuronal activity modulation, synaptic plasticity, disrupted key biological signaling pathways, and the novel candidate genes that play a significant role in the pathophysiology of ASD. The current emphasis on autism spectrum disorders has generated new opportunities in the field of neuroscience, and further advancements in the identification of different biomarkers, risk genes, and genetic pathways can help in the early diagnosis and development of new clinical and pharmacological treatments for ASD.

Sonic hedgehog patterning during cerebellar development

The morphogenic factor sonic hedgehog (Shh) actively orchestrates many aspects of cerebellar development and maturation. During embryogenesis, Shh signaling is active in the ventricular germinal zone (VZ) and represents an essential signal for proliferation of VZ-derived progenitors. Later, Shh secreted by Purkinje cells sustains the amplification of postnatal neurogenic niches: the external granular layer and the prospective white matter, where excitatory granule cells and inhibitory interneurons are produced, respectively. Moreover, Shh signaling affects Bergmann glial differentiation and promotes cerebellar foliation during development. Here we review the most relevant functions of Shh during cerebellar ontogenesis, underlying its role in physiological and pathological conditions.

Expression pattern of sonic hedgehog signaling and calcitonin gene-related peptide in the socket healing process after tooth extraction

Sonic Hedgehog (SHH), a neural development inducer, plays a significant role in the bone healing process. Calcitonin gene-related peptide (CGRP), a neuropeptide marker of sensory nerves, has been demonstrated to affect bone formation. The roles of SHH signaling and CGRP-positive sensory nerves in the alveolar bone formation process have been unknown. Here we examined the expression patterns of SHH signaling and CGRP in mouse socket by immunohistochemistry and immunofluorescence analysis. We found that the expression level of SHH peaked at day 3 and was then decreased at 5 days after tooth extraction. CGRP, PTCH1 and GLI2 were each expressed in a similar pattern with their highest expression levels at day 5 and day 7 after tooth extraction. CGRP and GLI2 were co-expressed in some inflammatory cells and bone forming cells. In some areas, CGRP-positive neurons expressed GLI2. In conclusion, SHH may affect alveolar bone healing by interacting with CGRP-positive sensory neurons and thus regulate the socket's healing process after tooth extraction.

Sonic hedgehog signalling pathway: a complex network

Sonic Hedgehog (Shh) signalling cascade is one of the intricate signal transduction mechanisms that govern the precisely regulated developmental processes of multicellular organisms. Along with establishing the patterns of cellular differentiation to direct complex organ formation, it also has an important role in post-embryonic tissue regeneration and repair processes. Especially, Shh signalling is implicated in the induction of multifarious neuronal populations in central nervous system. There is compelling evidence of the involvement of Shh protein in the signalling network that regulates various morphogenetic processes such as the exquisite neural tube pattern formation. In the morphogenetic field, the activation of Shh signalling processes is intricately linked to the alterations at the molecular level in the structure of Shh protein that leads to its altered biophysical and biochemical reactivity. This brief article gives an overview of such complex cascade of events in Shh signalling and its transduction pathways.

Holoprosencephaly: clinical evaluation on audiological and brainstem electrophysiological profiles

This study evaluated audiological and electrophysiological profiles in 13 patients with holoprosencephaly. All patients had imaging evaluation by magnetic resonance imaging and molecular screening for the genes SHH, GLI2, and SIX3. Each patient underwent clinical (otological and vestibular antecedents, otoscopy) and instrumental (tympanometry, auditory brainstem response--ABR) evaluation to compare hearing and the electrophysiological profile possibly occurring in patients with these mutations. To our knowledge there are no systematic studies correlating molecular/imaging and evoked potentials in patients with HPE. Here, we discuss the audiological and electrophysiological profiles of patients and the possible role of the genes studied on the overall findings.

Inhibition of epithelial ductal branching in the prostate by sonic hedgehog is indirectly mediated by stromal cells

Sonic hedgehog (Shh), a vertebrate homologue of the Drosophila segment-polarity gene hedgehog, has been reported to play an important role during normal development of various tissues. Abnormal activities of Shh signaling pathway have been implicated in tumorigenesis such as basal cell carcinomas and medulloblastomas. Here we show that Shh signaling negatively regulates prostatic epithelial ductal morphogenesis. In organotypic cultures of developing rat prostates, Shh inhibited cell proliferation and promoted differentiation of luminal epithelial cells. The expression pattern of Shh and its receptors suggests a paracrine mechanism of action. The Shh receptors Ptc1 (Patched1) and Ptc2 were found to be expressed in prostatic stromal cells adjacent to the epithelium, where Shh itself was produced. This paracrine model was confirmed by co-culturing the developing prostate in the presence of stromal cells transfected with a vector expressing a constitutively active form of Smoothened, the real effector of the Shh signaling pathway. Furthermore, expression of activin A and TGF-beta1 that were shown previously to inhibit prostatic epithelial branching was up-regulated following Shh treatment in the organotypic cultures. Taken together, these results suggest that Shh negatively regulates prostatic ductal branching indirectly by acting on the surrounding stromal cells, at least partly via up-regulating expression of activin A and TGF-beta1.