Sox10 and Itgb1 interaction in enteric neural crest cell migration

SOX10 promotes the malignant biological behavior of basal-like breast cancer cells by regulating EMT process

Background

The diagnostic utility of SRY-box transcription factor 10 (SOX10) expression in basal-like breast cancer (BLBC) has been reported previously. However, the effect of SOX10 on the malignancy of BLBC cells and the underlying molecular mechanisms remain unelucidated. Here, we investigate the regulatory mechanisms and roles of SOX10 in BLBC progression.

Methods

Sequencing data from patients with BLBC were extracted from the Cancer Genome Atlas database to determine the transcriptomic levels of SOX10 across breast cancer subtypes. Subsequently, the bioinformatics relevance of SOX10 in BLBC was investigated. Immunohistochemical assays were used to corroborate the protein expression of SOX10 in clinicopathological specimens (human breast cancer paraffin tissues). RNA interference was used to downregulate SOX10 expression, and the efficiency of interference was evaluated using quantitative PCR. The expression levels of molecules related to the epithelial-mesenchymal transition (EMT) pathway were determined by western blotting. Various assays, such as transwell, colony formation, and flow apoptosis assays, were conducted to assess the malignancy of BLBC cells (MDA-MB-231).

Results

Bioinformatics analyses revealed the differential expression of SOX10 in various breast cancer subtypes. An association between SOX10 and immune checkpoint expression was observed in BLBC. Additionally, immune correlation analysis indicated a positive relationship between SOX10 expression and effector immune cells. SOX10 was identified as a potential immunotherapeutic target. Juxtaposed with non-basal-like breast cancer (N-BLBC) and breast adenosis, immunohistochemical analysis revealed the upregulated expression of SOX10 in BLBC, indicating its potential diagnostic significance. Single-gene functional enrichment analysis indicated that SOX10 is associated with EMT and the tumor inflammatory index. Experimental outcomes from cellular assays suggested that the downregulation of SOX10 inhibited multiple malignancy-associated behaviors in MDA-MB-231 cells, specifically affecting the EMT process, migration, invasion, proliferation, clone formation, and anti-apoptotic activities.

Conclusions

We concluded that SOX10 contributes to the malignancy of BLBC cells by modulating the EMT pathway. Moreover, we observed a notable correlation between SOX10 expression and immune responses, indicating the potential significance of SOX10 in immunotherapy.

mRNA sequencing provides new insights into the pathogenesis of Hirschsprung's disease in mice

PURPOSE

The aim of this study is to use RNA sequencing and RT-qPCR to identify the main susceptibility genes linked to the occurrence and development of Hirschsprung disease in the colonic tissues of EDNRBm1yzcm and wild mice.

METHODS

RNA was extracted from colon tissues of 3 mutant homozygous mice and 3 wild mice. RNA degradation, contamination concentration, and integrity were then measured. The extracted RNA was then sequenced using the Illumina platform. The obtained sequence data are filtered to ensure data quality and compared to the reference genome for further analysis. DESeq2 was used for gene expression analysis of the raw data. In addition, graphene oxide enrichment analysis and RT-qPCR validation were also performed.

RESULTS

This study identified 8354 differentially expressed genes in EDNRBm1yzcm and wild mouse colon tissues by RNA sequencing, including 4346 upregulated genes and 4005 downregulated genes. Correspondingly, the results of RT-qPCR analysis showed good correlation with the transcriptome data. In addition, GO and KEGG enrichment results suggested that there were 8103 terms and 320 pathways in all DEGs. When P < 0.05, 1081 GO terms and 320 KEGG pathways reached a significant level. Finally, through the existing studies and the enrichment results of differentially expressed genes, it was determined that axon guidance and the focal adhesion pathway may be closely related to the occurrence of HSCR.

CONCLUSIONS

This study analyzed and identified the differential genes in colonic tissues between EDNRBm1yzcm mice and wild mice, which provided new insight for further mining the potential pathogenic genes of Hirschsprung's disease.

A distinct transcriptome characterizes neural crest-derived cells at the migratory wavefront during enteric nervous system development

Enteric nervous system development relies on intestinal colonization by enteric neural crest-derived cells (ENCDCs). This is driven by a population of highly migratory and proliferative ENCDCs at the wavefront, but the molecular characteristics of these cells are unknown. ENCDCs from the wavefront and the trailing region were isolated and subjected to RNA-seq. Wavefront-ENCDCs were transcriptionally distinct from trailing ENCDCs, and temporal modelling confirmed their relative immaturity. This population of ENCDCs exhibited altered expression of ECM and cytoskeletal genes, consistent with a migratory phenotype. Unlike trailing ENCDCs, the wavefront lacked expression of genes related to neuronal or glial maturation. As wavefront ENCDC genes were associated with migration and developmental immaturity, the genes that remain expressed in later progenitor populations may be particularly pertinent to understanding the maintenance of ENCDC progenitor characteristics. Dusp6 expression was specifically upregulated at the wavefront. Inhibiting DUSP6 activity prevented wavefront colonization of the hindgut, and inhibited the migratory ability of post-colonized ENCDCs from midgut and postnatal neurospheres. These effects were reversed by simultaneous inhibition of ERK signaling, indicating that DUSP6-mediated ERK inhibition is required for ENCDC migration in mouse and chick.

Direct Interaction of Sox10 With Cadherin-19 Mediates Early Sacral Neural Crest Cell Migration: Implications for Enteric Nervous System Development Defects

BACKGROUND AND AIMS

The enteric nervous system, which regulates many gastrointestinal functions, is derived from neural crest cells (NCCs). Defective NCC migration during embryonic development may lead to enteric neuropathies such as Hirschsprung's disease (hindgut aganglionosis). Sox10 is known to be essential for cell migration but downstream molecular events regulating early NCC migration have not been fully elucidated. This study aimed to determine how Sox10 regulates migration of sacral NCCs toward the hindgut using Dominant megacolon mice, an animal model of Hirschsprung's disease with a Sox10 mutation.

METHODS

We used the following: time-lapse live cell imaging to determine the migration defects of mutant sacral NCCs; genome-wide microarrays, site-directed mutagenesis, and whole embryo culture to identify Sox10 targets; and liquid chromatography and tandem mass spectrometry to ascertain downstream effectors of Sox10.

RESULTS

Sacral NCCs exhibited retarded migration to the distal hindgut in Sox10-null embryos with simultaneous down-regulated expression of cadherin-19 (Cdh19). Sox10 was found to bind directly to the Cdh19 promoter. Cdh19 knockdown resulted in retarded sacral NCC migration in vitro and ex vivo, whereas re-expression of Cdh19 partially rescued the retarded migration of mutant sacral NCCs in vitro. Cdh19 formed cadherin-catenin complexes, which then bound to filamentous actin of the cytoskeleton during cell migration.

CONCLUSIONS

Cdh19 is a direct target of Sox10 during early sacral NCC migration toward the hindgut and forms cadherin-catenin complexes which interact with the cytoskeleton in migrating cells. Elucidation of this novel molecular pathway helps to provide insights into the pathogenesis of enteric nervous system developmental defects.

LncRNA DRAIC regulates cell proliferation and migration by affecting the miR-34a-5p/ITGA6 signal axis in Hirschsprung's disease

BACKGROUND

Hirschsprung's disease (HSCR) is a common defect in newborns, and studies have revealed that long non-coding RNA (lncRNA) is involved in the progression of HSCR. This research study aims to investigate the mechanism of downregulated RNA in cancer (DRAIC) on cell proliferation and migration in HSCR.

METHODS

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the expression of DRAIC in HSCR bowel stenosis tissues and normal colon tissues. Cell-counting kit-8 (CCK-8) and Transwell assays were employed to explore whether cellular functions change after overexpression or knockdown of the DRAIC in SH-SY5Y cells and human 293T cells. Protein expression levels were determined by Western blot analysis. RNA pull-down and dual-luciferase reporter assays were used to confirm the competitive relationship of DRAIC and integrin subunit alpha 6 (ITGA6) through their association with miR-34a-5p.

RESULTS

The lncRNA DRAIC was significantly increased in colon tissue from HSCR patients. The overexpression of DRAIC inhibited SH-SY5Y cell and human 293T cell proliferation and migration. Knockdown of DRAIC, however, promoted cell proliferation and migration. The RNA pull-down and dual-luciferase reporter assays have proven the competitive relationship between DRAIC and ITGA6 through their association with miR-34a-5p. Further rescue experiments have confirmed that DRAIC regulates cell proliferation and migration by affecting the miR-34a-5p/ITGA6 signal axis in HSCR.

CONCLUSION

DRAIC promoted cell proliferation and migration by regulating the miR-34a-5p/ITGA6 signal axis in HSCR.

Common variants of NRG1 and ITGB4 confer risk of Hirschsprung disease in Han Chinese population

BACKGROUND

Hirschsprung disease (HSCR) is a neurodevelopmental disorder with a strong genetic component. Common variants of NRG1 contributed to HSCR risk in Asians, and rare variants of ERBB2 and ITGB4 were found to be associated with HSCR. ERBB2 and ITGB4 are partners of Nrg1/ErbB pathway, which is important in HSCR pathogenesis. We aimed to investigate whether common variants in NRG1, ERBB2 and ITGB4 were associated with HSCR in Chinese Han population.

METHODS

We genotype 17 single nucleotide polymorphisms (SNPs) of NRG1, ERBB2 and ITGB4 in 420 HSCR patients and 1665 controls, and performed association analysis.

RESULTS

We validated associations of two NRG1 SNPs rs7835688 (P_Allelic = 2.2 × 10^-20, OR = 2.21, 95%CI = 1.86-2.62) and rs16879552 (P_Allelic = 5.6 × 10^-9, OR = 1.57, 95%CI = 1.35-1.83) with risk to HSCR. SNP rs3744000 located 5' upstream of ITGB4 showed association with HSCR (P_Allelic = 2.4 × 10^-3, OR = 1.27, 95%CI = 1.09-1.49). Four SNPs of ERBB2 exhibited no association.

CONCLUSIONS

Our results suggested that common variation of ITGB4 and NRG1 conferred risk to HSCR in Chinese Han population, which further highlighted Nrg-1/ErbB pathway involving in the pathogenesis of HSCR.

Transcription factor Ptf1a in development, diseases and reprogramming

The transcription factor Ptf1a is a crucial helix-loop-helix (bHLH) protein selectively expressed in the pancreas, retina, spinal cord, brain, and enteric nervous system. Ptf1a is preferably assembled into a transcription trimeric complex PTF1 with an E protein and Rbpj (or Rbpjl). In pancreatic development, Ptf1a is indispensable in controlling the expansion of multipotent progenitor cells as well as the specification and maintenance of the acinar cells. In neural tissues, Ptf1a is transiently expressed in the post-mitotic cells and specifies the inhibitory neuronal cell fates, mostly mediated by downstream genes such as Tfap2a/b and Prdm13. Mutations in the coding and non-coding regulatory sequences resulting in Ptf1a gain- or loss-of-function are associated with genetic diseases such as pancreatic and cerebellar agenesis in the rodent and human. Surprisingly, Ptf1a alone is sufficient to reprogram mouse or human fibroblasts into tripotential neural stem cells. Its pleiotropic functions in many biological processes remain to be deciphered in the future.

News from the endothelin-3/EDNRB signaling pathway: Role during enteric nervous system development and involvement in neural crest-associated disorders

The endothelin system is a vertebrate-specific innovation with important roles in regulating the cardiovascular system and renal and pulmonary processes, as well as the development of the vertebrate-specific neural crest cell population and its derivatives. This system is comprised of three structurally similar 21-amino acid peptides that bind and activate two G-protein coupled receptors. In 1994, knockouts of the Edn3 and Ednrb genes revealed their crucial function during development of the enteric nervous system and melanocytes, two neural-crest derivatives. Since then, human and mouse genetics, combined with cellular and developmental studies, have helped to unravel the role of this signaling pathway during development and adulthood. In this review, we will summarize the known functions of the EDN3/EDNRB pathway during neural crest development, with a specific focus on recent scientific advances, and the enteric nervous system in normal and pathological conditions.

Exposure to GDNF Enhances the Ability of Enteric Neural Progenitors to Generate an Enteric Nervous System

Cell therapy is a promising approach to generate an enteric nervous system (ENS) and treat enteric neuropathies. However, for translation to the clinic, it is highly likely that enteric neural progenitors will require manipulation prior to transplantation to enhance their ability to migrate and generate an ENS. In this study, we examine the effects of exposure to several factors on the ability of ENS progenitors, grown as enteric neurospheres, to migrate and generate an ENS. Exposure to glial-cell-line-derived neurotrophic factor (GDNF) resulted in a 14-fold increase in neurosphere volume and a 12-fold increase in cell number. Following co-culture with embryonic gut or transplantation into the colon of postnatal mice in vivo, cells derived from GDNF-treated neurospheres showed a 2-fold increase in the distance migrated compared with controls. Our data show that the ability of enteric neurospheres to generate an ENS can be enhanced by exposure to appropriate factors.

•

Enteric neurospheres are likely to require manipulation for clinical applications

•

Exposure to GDNF increased the size and cell number in enteric neurospheres

•

GDNF-treated neurospheres showed enhanced migration after transplantation in vivo

•

Manipulation of enteric neurospheres can enhance the generation of enteric neurons

Endothelin-3 stimulates cell adhesion and cooperates with β1-integrins during enteric nervous system ontogenesis

Endothelin-3 (EDN3) and β1-integrins are required for the colonization of the embryonic gut by enteric neural crest cells (ENCCs) to form the enteric nervous system (ENS). β1-integrin-null ENCCs exhibit migratory defects in a region of the gut enriched in EDN3 and in specific extracellular matrix (ECM) proteins. We investigated the putative role of EDN3 on ENCC adhesion properties and its functional interaction with β1-integrins during ENS development. We show that EDN3 stimulates ENCC adhesion to various ECM components in vitro. It induces rapid changes in ENCC shape and protrusion dynamics favouring sustained growth and stabilization of lamellipodia, a process coincident with the increase in the number of focal adhesions and activated β1-integrins. In vivo studies and ex-vivo live imaging revealed that double mutants for Itgb1 and Edn3 displayed a more severe enteric phenotype than either of the single mutants demonstrated by alteration of the ENS network due to severe migratory defects of mutant ENCCs taking place early during the ENS development. Altogether, our results highlight the interplay between the EDN3 and β1-integrin signalling pathways during ENS ontogenesis and the role of EDN3 in ENCC adhesion.

Mouse models of Hirschsprung disease and other developmental disorders of the enteric nervous system: Old and new players

Hirschsprung disease (HSCR, intestinal aganglionosis) is a multigenic disorder with variable penetrance and severity that has a general population incidence of 1/5000 live births. Studies using animal models have contributed to our understanding of the developmental origins of HSCR and the genetic complexity of this disease. This review summarizes recent progress in understanding control of enteric nervous system (ENS) development through analyses in mouse models. An overview of signaling pathways that have long been known to control the migration, proliferation and differentiation of enteric neural progenitors into and along the developing gut is provided as a framework for the latest information on factors that influence enteric ganglia formation and maintenance. Newly identified genes and additional factors beyond discrete genes that contribute to ENS pathology including regulatory sequences, miRNAs and environmental factors are also introduced. Finally, because HSCR has become a paradigm for complex oligogenic diseases with non-Mendelian inheritance, the importance of gene interactions, modifier genes, and initial studies on genetic background effects are outlined.

Control of the collective migration of enteric neural crest cells by the Complement anaphylatoxin C3a and N-cadherin

We analyzed the cellular and molecular mechanisms governing the adhesive and migratory behavior of enteric neural crest cells (ENCCs) during their collective migration within the developing mouse gut. We aimed to decipher the role of the complement anaphylatoxin C3a during this process, because this well-known immune system attractant has been implicated in cephalic NCC co-attraction, a process controlling directional migration.

We used the conditional Ht-PA-cre transgenic mouse model allowing a specific ablation of the N-cadherin gene and the expression of a fluorescent reporter in migratory ENCCs without affecting the central nervous system. We performed time-lapse videomicroscopy of ENCCs from control and N-cad-herin mutant gut explants cultured on fibronectin (FN) and micropatterned FN-stripes with C3a or C3aR antagonist, and studied cell migration behavior with the use of triangulation analysis to quantify cell dispersion. We performed ex vivo gut cultures with or without C3aR antagonist to determine the effect on ENCC behavior. Confocal microscopy was used to analyze the cell-matrix adhesion properties. We provide the first demonstration of the localization of the complement anaphylatoxin C3a and its receptor on ENCCs during their migration in the embryonic gut. C3aR receptor inhibition alters ENCC adhesion and migration, perturbing directionality and increasing cell dispersion both in vitro and ex vivo. N-cad-herin-null ENCCs do not respond to C3a co-attraction. These findings indicate that C3a regulates cell migration in a N-cadherin-dependent process. Our results shed light on the role of C3a in regulating collective and directional cell migration, and in ganglia network organization during enteric nervous system ontogenesis. The detection of an immune system chemokine in ENCCs during ENS development may also shed light on new mechanisms for gastrointestinal disorders.

How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration

Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.

A Sox10(rtTA/+) Mouse Line Allows for Inducible Gene Expression in the Auditory and Balance Organs of the Inner Ear

Genetic mouse models provide invaluable tools for discerning gene function in vivo. Tetracycline-inducible systems (Tet-On/Off) provide temporal and cell-type specific control of gene expression, offering an alternative or even complementary approach to existing Cre/LoxP systems. Here we characterized a Sox10(rtTA/+) knock-in mouse line which demonstrates inducible reverse tetracycline trans-activator (rtTA) activity and Tet-On transgene expression in the inner ear following induction with the tetracycline derivative doxycycline (Dox). These Sox10(rtTA/+) mice do not exhibit any readily observable developmental or hearing phenotypes, and actively drive Tet-On transgene expression in Sox10 expressing cells in the inner ear. Sox10(rtTA/+) activity was revealed by multiple Tet-On reporters to be nearly ubiquitous throughout the membranous labyrinth of the developing inner ear, and notably absent from hair cells, tympanic border cells, and ganglion neurons following postnatal Dox inductions. Interestingly, Dox-induced Sox10(rtTA/+) activity declined with induction age, where Tet-On reporters became uninducible in adult cochlear epithelium. Co-administration of the loop diuretic furosemide was able to rescue Dox-induced reporter expression, though this method also caused significant cochlear hair cell loss. Surprisingly, Sox10(rtTA/+) driven reporter expression in the cochlea persists for at least 54 days after cessation of neonatal induction, presumably due to the persistence of Dox within inner ear tissues. These findings highlight the utility of the Sox10(rtTA/+) mouse line as a powerful tool for functional genetic studies of the auditory and balance organs in vivo, but also reveal some important considerations that must be adequately controlled for in future studies that rely upon Tet-On/Off systems.

MiR-195 affects cell migration and cell proliferation by down-regulating DIEXF in Hirschsprung's disease

Background

Hirschsprung’s disease (HSCR) is the most common congenital gut motility disorder. We aimed to investigate the roles of miR-195 in the pathogenesis of HSCR.

Methods

In this study, we measured the expression levels of miRNA, mRNA, and protein in colon tissues from 78 patients with HSCR and 66 controls without HSCR. Transwell, Cell Counting Kit-8 (CCK-8) and flow cytometry assay were employed to detect the function role of miR-195 in vitro.

Results

Our results showed that expression levels of miR-195 from patients with HSCR were significantly higher than control group; along with aberrant lower expression levels of digestive-organ expansion factor (DIEXF) were tested. Increased level of miR-195 could suppress the level of DIEXF in cell, which induced the impairment of cell migration and proliferation.

Conclusions

Aberrant expression of miR-195 may involved in the pathogenesis of HSCR by down-regulated the level of DIEXF.

Colonizing while migrating: how do individual enteric neural crest cells behave?

Background

Directed cell migration is essential for normal development. In most of the migratory cell populations that have been analyzed in detail to date, all of the cells migrate as a collective from one location to another. However, there are also migratory cell populations that must populate the areas through which they migrate, and thus some cells get left behind while others advance. Very little is known about how individual cells behave to achieve concomitant directional migration and population of the migratory route. We examined the behavior of enteric neural crest-derived cells (ENCCs), which must both advance caudally to reach the anal end and populate each gut region.

Results

The behavior of individual ENCCs was examined using live imaging and mice in which ENCCs express a photoconvertible protein. We show that individual ENCCs exhibit very variable directionalities and speed; as the migratory wavefront of ENCCs advances caudally, each gut region is populated primarily by some ENCCs migrating non-directionally. After populating each region, ENCCs remain migratory for at least 24 hours. Endothelin receptor type B (EDNRB) signaling is known to be essential for the normal advance of the ENCC population. We now show that perturbation of EDNRB principally affects individual ENCC speed rather than directionality. The trajectories of solitary ENCCs, which occur transiently at the wavefront, were consistent with an unbiased random walk and so cell-cell contact is essential for directional migration. ENCCs migrate in close association with neurites. We showed that although ENCCs often use neurites as substrates, ENCCs lead the way, neurites are not required for chain formation and neurite growth is more directional than the migration of ENCCs as a whole.

Conclusions

Each gut region is initially populated by sub-populations of ENCCs migrating non-directionally, rather than stopping. This might provide a mechanism for ensuring a uniform density of ENCCs along the growing gut.

Simple rules for a "simple" nervous system? Molecular and biomathematical approaches to enteric nervous system formation and malformation

We review morphogenesis of the enteric nervous system from migratory neural crest cells, and defects of this process such as Hirschsprung disease, centering on cell motility and assembly, and cell adhesion and extracellular matrix molecules, along with cell proliferation and growth factors. We then review continuum and agent-based (cellular automata) models with rules of cell movement and logistical proliferation. Both movement and proliferation at the individual cell level are modeled with stochastic components from which stereotyped outcomes emerge at the population level. These models reproduced the wave-like colonization of the intestine by enteric neural crest cells, and several new properties emerged, such as colonization by frontal expansion, which were later confirmed biologically. These models predict a surprising level of clonal heterogeneity both in terms of number and distribution of daughter cells. Biologically, migrating cells form stable chains made up of unstable cells, but this is not seen in the initial model. We outline additional rules for cell differentiation into neurons, axon extension, cell-axon and cell-cell adhesions, chemotaxis and repulsion which can reproduce chain migration. After the migration stage, the cells re-arrange as a network of ganglia. Changes in cell adhesion molecules parallel this, and we describe additional rules based on Steinberg's Differential Adhesion Hypothesis, reflecting changing levels of adhesion in neural crest cells and neurons. This was able to reproduce enteric ganglionation in a model. Mouse mutants with disturbances of enteric nervous system morphogenesis are discussed, and these suggest future refinement of the models. The modeling suggests a relatively simple set of cell behavioral rules could account for complex patterns of morphogenesis. The model has allowed the proposal that Hirschsprung disease is mostly an enteric neural crest cell proliferation defect, not a defect of cell migration. In addition, the model suggests an explanations for zonal and skip segment variants of Hirschsprung disease, and also gives a novel stochastic explanation for the observed discordancy of Hirschsprung disease in identical twins.