Signaling Molecule Sonic Hedgehog Research Articles

Does the sonic hedgehog signaling pathway play a role in anti-reflux mechanism of bladder in children?

A hedgehog family ligand, namely, sonic hedgehog (SHH), was reported to be important in the development of bladder and ureter smooth muscle. In this prospective study, we aimed to determine protein expression of SHH in resected ureterovesical junction (UVJ) segments of children with vesicoureteral reflux (VUR). The study group included 19 children; 12 (63%) girls, 7 (37%) boys, who had ureteroneocystostomy operation; 3 (15.7%) right sided, 7 (36.8%) left sided, 9 (47.3%) bilateral, due to primary VUR between years 2015 and 2018. Totally, 28 UVJ segments were examined for Western Blot analysis to determine related protein expression levels. The mean Western blot band area of SHH gene pathway related protein was 3880.69 (2059.55-13941.61) while the mean area of β-Actin, the house-keeping gene, was 20180.25 (9530.39-26709.75) (p = 0.001). Correlation analyses between grade of reflux and protein expression of SHH gene pathways revealed no significant relation (p = 0.300). When the UV samples were grouped as low- and high-grade reflux and compared in terms of SHH protein expression levels, no statistically significant difference was found between groups (p = 0.818). We concluded that SHH signaling molecule which is effective in development of bladder and ureter smooth musculature might also be effective in etiopathology of reflux.

Siponimod ameliorates experimental autoimmune neuritis

BackgroundGuillain–Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) are human autoimmune peripheral neuropathy. Besides humoral immunity, cellular immunity is also believed to contribute to these pathologies, especially CIDP. Sphingosine-1-phosphate receptor 1 (S1PR1) regulates the maturation, migration, and trafficking of lymphocytes. As of date, the therapeutic effect of sphingosine-1-phosphate receptor (S1PR) agonists on patients with GBS or CIDP remains unclear.MethodsTo evaluate the effect of siponimod, an agonist of S1PR1 and S1PR5, on experimental autoimmune neuritis (EAN), an animal model of autoimmune peripheral neuropathy, was used. Lewis rats were immunized with 125 μg of synthetic peptide from bovine P2 protein. Rats in the siponimod group were orally administered 1.0 mg/kg siponimod and those in the EAN group were administrated the vehicle on days 5–27 post-immunization (p.i.) daily. The symptom severity was recorded daily. The changes in the expression of cytokines and transcription factors in the lymph nodes and cauda equina (CE) which correlate with the pathogenesis of EAN and recovery of injured nerve were measured using reverse transcription quantitative PCR. Histological study of CE was also performed.ResultsFlaccid paralysis developed on day 11 p.i. in both groups. Siponimod relieved the symptom severity and decreased the expression of interferon-gamma and IL-10 mRNAs in lymph nodes and CE compared with that in the EAN group. The expression of Jun proto-oncogene (c-Jun) mRNA increased from the peak to the recovery phase and that of Sonic hedgehog signaling molecule (Shh) and Glial cell line-derived neurotrophic factor (Gdnf) increased prior to increase in c-Jun with no difference observed between the two groups. Histologically, siponimod also reduced demyelinating lesions and inflammatory cell invasion in CE.ConclusionsSiponimod has a potential to ameliorate EAN. Shh and Gdnf, as well as C-Jun played a significant role during the recovery of injured nerves.

Sonic Hedgehog Intron Variant Associated With an Unusual Pediatric Cortical Cataract.

PurposeTo identify the genetic basis of an unusual pediatric cortical cataract demonstrating autosomal dominant inheritance in a large European–Australian pedigree.MethodsDNA from four affected individuals were exome sequenced utilizing a NimbleGen SeqCap EZ Exome V3 kit and HiSeq 2500. DNA from 12 affected and four unaffected individuals were genotyped using Human OmniExpress-24 BeadChips. Multipoint linkage and haplotyping were performed (Superlink-Online SNP). DNA from one affected individual and his unaffected father were whole-genome sequenced on a HiSeq X Ten system. Rare small insertions/deletions and single-nucleotide variants (SNVs) were identified in the disease-linked region (Golden Helix SVS). Combined Annotation Dependent Depletion (CADD) analysis predicted variant deleteriousness. Putative enhancer function and variant effects were determined using the Dual-Glo Luciferase Assay system.ResultsLinkage mapping identified a 6.23-centimorgan support interval at chromosome 7q36. A co-segregating haplotype refined the critical region to 6.03 Mbp containing 21 protein-coding genes. Whole-genome sequencing uncovered 114 noncoding variants from which CADD predicted one was highly deleterious, a novel substitution within intron-1 of the sonic hedgehog signaling molecule (SHH) gene. ENCODE data suggested this site was a putative enhancer, subsequently confirmed by luciferase reporter assays with variant-associated gene overexpression.ConclusionsIn a large pedigree, we have identified a SHH intron variant that co-segregates with an unusual pediatric cortical cataract phenotype. SHH is important for lens formation, and mutations in its receptor (PTCH1) cause syndromic cataract. Our data implicate increased function of an enhancer important for SHH expression primarily within developing eye tissues.

Expression and significance of GLI1 and Shh in the malignant transformation of ovarian endometriosis

Objective: To investigate the expression levels and clinical significance of glioma-associated oncogene homolog 1 (GLI1) and sonic hedgehog signaling molecule (Shh) in the malignant transformation of ovarian endometriosis (EM). Methods: The expressions of GLI1 and Shh were detected by real-time reverse transcription (RT)-polymerase chain reaction (PCR) and EnVision method in 50 cases of ovarian EM tissues, 35 cases of atypical endometriosis (aEM) and 50 cases of endometriosis-associated ovarian cancer (EAOC). The expression differences of two molecular markers in the malignant transformation of ovarian EM were compared, and the relationships between two molecular markers and the clinicopathological features and prognosis of EAOC were analyzed. Results: (1) RT-PCR showed that the expression levels of GLI1 mRNA in EM, aEM and EAOC group were 1.77±0.40, 3.54±0.44, and 7.80±0.24, respectively. The expression levels of Shh mRNA were 0.95±0.21, 3.14±0.35, and 5.41±0.31, respectively. GLI1 and Shh mRNA in EAOC group were significantly higher than those in EM and aEM group (all P<0.01), and there were statistically significant differences between EM and aEM group (all P<0.01). The percentages of GLI1 in ovarian EM, aEM and EAOC were 32% (16/50), 57% (20/35), and 66% (33/50), respectively, meanwhile, the positive expression rates of Shh were 20% (10/50), 49% (17/35), and 54% (27/50), respectively (all P<0.01). GLI1 mRNA expression was positively correlated with Shh mRNA expression in EAOC tissues (r=0.721, P<0.01). The expressions of GLI1 protein were proportionated to Shh protein in EAOC tissues (r=0.608,P=0.001). (2) The expression of GLI1 was significantly related to the International Federation of Gynecology and Obstetrics (FIGO) stage, cancer antigen 125 (CA125) levels, lymph node metastasis, and Platinum resistance in EAOC patients (all P<0.05). The expression of Shh were related to FIGO stage and lymph node metastasis in EAOC patients (all P<0.05). Logistic regression analysis showed that GLI1 expression was an independent risk factor for poor prognosis in EAOC patients (P<0.05). Kaplan-meier survival analysis showed that the overall survival rate of EAOC patients with high GLI1 expression and low GLI1 expression was 12.1% and 35.3%, respectively, with statistical significance (χ²=10.73, P<0.01). The overall survival rate of EAOC patients with high and low expression of Shh protein was 11.1% and 30.4%, in which there was statistically significant difference (χ²=3.96, P=0.047). Conclusion: GLI1 and Shh are highly associated with the malignant transformation of ovarian EM, which may play a role in promoting malignant degeneration of ovarian EM, and the high expression of GLI1 and Shh indicates a poor prognosis in EAOC patients.

Gas1 Regulates Patterning of the Murine and Human Dentitions through Sonic Hedgehog

The mammalian dentition is a serially homogeneous structure that exhibits wide numerical and morphological variation among multiple different species. Patterning of the dentition is achieved through complex reiterative molecular signaling interactions that occur throughout the process of odontogenesis. The secreted signaling molecule Sonic hedgehog (Shh) plays a key role in this process, and the Shh coreceptor growth arrest-specific 1 (Gas1) is expressed in odontogenic mesenchyme and epithelium during multiple stages of tooth development. We show that mice engineered with Gas1 loss-of-function mutation have variation in number, morphology, and size of teeth within their molar dentition. Specifically, supernumerary teeth with variable morphology are present mesial to the first molar with high penetrance, while molar teeth are characterized by the presence of both additional and absent cusps, combined with reduced dimensions and exacerbated by the presence of a supernumerary tooth. We demonstrate that the supernumerary tooth in Gas1 mutant mice arises through proliferation and survival of vestigial tooth germs and that Gas1 function in cranial neural crest cells is essential for the regulation of tooth number, acting to restrict Wnt and downstream FGF signaling in odontogenic epithelium through facilitation of Shh signal transduction. Moreover, regulation of tooth number is independent of the additional Hedgehog coreceptors Cdon and Boc, which are also expressed in multiple regions of the developing tooth germ. Interestingly, further reduction of Hedgehog pathway activity in Shhtm6Amc hypomorphic mice leads to fusion of the molar field and reduced prevalence of supernumerary teeth in a Gas1 mutant background. Finally, we demonstrate defective coronal morphology and reduced coronal dimensions in the molar dentition of human subjects identified with pathogenic mutations in GAS1 and SHH/GAS1, suggesting that regulation of Hedgehog signaling through GAS1 is also essential for normal patterning of the human dentition.

Increased Expression of p63 Protein and Sonic Hedgehog Signaling Molecule in Buccal Epithelial Holoclones.

Construction of many tissues and organs de novo requires the use of external epithelial cell sources. In the present study, we optimized the isolation, expansion, and characterization of porcine oral epithelial cells from buccal tissue (Buccal Epithelial Cells, BECs). Additionally, we tested whether key markers [cytokeratin 14 (ck14), p63 protein, and sonic hedgehog molecule (shh)] expression profiles are correlated with three buccal epithelial clone types. Two digestion methods of BECs isolation [Method 1, M1 (collagenase IV/dispase and accutase) and Method 2, M2 (collagenase IV/dispase and trypsin/EDTA)] were compared. Cells obtained by more effective method were further cultured to the third passage and analyzed. Holoclone-, meroclone-, and paraclone-like colonies were identified based on BEC morphology. Immunofluorescent staining was performed to compare selected markers for the indicated buccal clone types. Comparative analysis demonstrated the advantage of isolation using M1 over M2. Cells from the third passage exhibited average 92.73% ± 2.27% presence of ck14. Real-time polymerase chain reaction confirmed expression of tested genes [cytokeratin 8 (ck8), ck14, integrin β1, and p63]. The highest level of ck14, shh and p63, was observed for holoclones. The comparable ck14 expression was observed in the mero- and paraclones. Meroclones expressed significantly lower levels of shh compared with paraclones. The weakest p63 expression was observed in the paraclone-like cells. It was demonstrated that holoclones are the richest in shh (+) and p63 (+) stem cells and these cells should appear to be a promising alternative for obtaining epithelial cells for tissue engineering purposes.

MicroRNA-26a inhibits cell proliferation and invasion by targeting FAM98A in breast cancer.

MicroRNAs (miRNAs/miRs) play key roles in cancer progression. Extensive research has revealed that miR-26a is abnormally expressed and functions as a tumor suppressor in numerous types of cancer. Thus, the present study was undertaken to investigate the regulatory role and potential mechanism of action of miR-26a in breast cancer. Furthermore, the present study aimed to examine the alterations in miR-26a expression and its effects on human breast cancer cells. Reverse transcription-quantitative PCR was conducted to assess the differences in miR-26a expression between human breast cancer and normal breast specimens. A Cell Counting Kit-8 assay and cloning experiments were used to detect cell proliferation and clone formation. Wound healing and Transwell assays were performed to examine cell migration and invasion. A luciferase activity experiment was utilized to validate the association between miR-26a and family with sequence similarity 98 member A (FAM98A). Western blotting was conducted to detect the protein expression levels of FAM98A, sonic hedgehog signaling molecule (SHH), smoothened, frizzled class receptor (SMO) and GLI family zinc finger 1 (GLI1). The results indicated that miR-26a expression was decreased in breast carcinoma tissues and cell lines. Moreover, overexpression of miR-26a significantly suppressed cell proliferation, clone formation ability and metastasis, and it sensitized breast cancer cells to docetaxel. It was demonstrated that miR-26a directly targeted FAM98A, and that FAM98A, SHH, SMO and GLI1 expression levels were decreased in cells transfected with miR-26a mimics. Collectively, the results of the present study suggested that miR-26a negatively regulated the expression of FAM98A, indicating that it may play a key role in the suppression of breast carcinogenesis.

Rare hypomorphic human variation in the heptahelical domain of SMO contributes to holoprosencephaly phenotypes.

Holoprosencephaly (HPE) is the most common congenital anomaly affecting the forebrain and face in humans and occurs as frequently as 1:250 conceptions or 1:10,000 livebirths. Sonic Hedgehog signaling molecule is one of the best characterized HPE genes that plays crucial roles in numerous developmental processes including midline neural patterning and craniofacial development. The Frizzled class G-protein coupled receptor Smoothened (SMO), whose signaling activity is tightly regulated, is the sole obligate transducer of Hedgehog-related signals. However, except for previous reports of somatic oncogenic driver mutations in human cancers (or mosaic tumors in rare syndromes), any potential disease-related role of SMO genetic variation in humans is largely unknown. To our knowledge, ours is the first report of a human hypomorphic variant revealed by functional testing of seven distinct nonsynonymous SMO variants derived from HPE molecular and clinical data. Here we describe several zebrafish bioassays developed and guided by a systems biology analysis. This analysis strategy, and detection of hypomorphic variation in human SMO, demonstrates the necessity of integrating the genomic variant findings in HPE probands with other components of the Hedgehog gene regulatory network in overall medical interpretations.

An SGLT2 inhibitor modulates SHH expression by activating AMPK to inhibit the migration and induce the apoptosis of cervical carcinoma cells

In addition to their hypoglycemic effect, sodium-glucose cotransporter 2 (SGLT2) inhibitors have many other benefits. In the present study, we examine the anticancer effect of the SGLT2 inhibitor empagliflozin using cervical carcinoma models. In vivo antitumor activities of empagliflozin were observed in a nude mouse model. Empagliflozin intervention and downregulation of Sonic Hedgehog Signaling Molecule (Shh) inhibited the migration and promoted the apoptosis of cervical cancer cells in nude mice. Compared with the control group, the empagliflozin treatment group had an increased level of AMP-activated protein kinase (AMPK) and decreased levels of Forkhead Box A1 (FOXA1) and SHH in tumor tissue. In vitro experiments also showed that empagliflozin (50μM) inhibited the migration of cervical cancer cells and induced their apoptosis by activating the AMPK/FOXA1 pathway and inhibiting the expression of SHH. Kaplan-Meier survival analysis was used to determine the relationship between SHH expression and total survival time. The results showed that in cervical cancer patients, high SHH expression resulted in unfavorable overall survival. The downregulation of SHH with small interfering RNA (siRNA) inhibited the migration and invasion and promoted the apoptosis of HeLa cells. These findings show that empagliflozin has a potential therapeutic effect on cervical cancer. This effect was related to the activation of the AMPK pathway and the inhibition of SHH expression.

Cortical Neural Stem Cell Lineage Progression Is Regulated by Extrinsic Signaling Molecule Sonic Hedgehog

SUMMARYNeural stem cells (NSCs) in the prenatal neocortex progressively generate different subtypes of glutamatergic projection neurons. Following that, NSCs have a major switch in their progenitor properties and produce γ-aminobutyric acid (GABAergic) interneurons for the olfactory bulb (OB), cortical oligodendrocytes, and astrocytes. Herein, we provide evidence for the molecular mechanism that underlies this switch in the state of neocortical NSCs. We show that, at around E16.5, mouse neocortical NSCs start to generate GSX2-expressing (GSX2+) intermediate progenitor cells (IPCs). In vivo lineage-tracing study revealed that GSX2+ IPC population gives rise not only to OB interneurons but also to cortical oligodendrocytes and astrocytes, suggesting that they are a tri-potential population. We demonstrated that Sonic hedgehog signaling is both necessary and sufficient for the generation of GSX2+ IPCs by reducing GLI3R protein levels. Using single-cell RNA sequencing, we identify the transcriptional profile of GSX2+ IPCs and the process of the lineage switch of cortical NSCs.

Sonic Hedgehog, a Novel Endogenous Damage Signal, Activates Multiple Beneficial Functions of Human Endometrial Stem Cells.

Local endometrial stem cells play an important role in regulating endometrial thickness, which is an essential factor for successful embryo implantation and pregnancy outcomes. Importantly, defects in endometrial stem cell function can be responsible for thin endometrium and subsequent recurrent pregnancy losses. Therefore, many researchers have directed their efforts toward finding a novel stimulatory factor that can enhance the regenerative capacity of endometrial stem cells. Sonic hedgehog (SHH) is a morphogen that plays a key role in regulating pattern formation throughout embryonic limb development. In addition to this canonical function, we identified for the first time that SHH is actively secreted as a stem cell-activating factor in response to tissue injury and subsequently stimulates tissue regeneration by promoting various beneficial functions of endometrial stem cells. Our results also showed that SHH exerts stimulatory effects on endometrial stem cells via the FAK/ERK1/2 and/or phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways. More importantly, we also observed that endometrial stem cells stimulated with SHH showed markedly enhanced differentiation and migratory capacities and subsequent invivo therapeutic effects in an endometrial ablation animal model.

Dauricine suppresses the growth of pancreatic cancer in vivo by modulating the Hedgehog signaling pathway.

Pancreatic cancer is a highly malignant cancer associated with high expression levels of sonic hedgehog signaling molecule (Shh), patched 1 (Ptch1), smoothened frizzled class receptor (Smo) and glioma-associated oncogene family zinc finger 1 (Gli1) in the hedgehog (Hh) signaling pathway. Inhibition of the Hh signaling pathway is a potential therapeutic target for pancreatic cancer. The aim of the present study was to investigate the effects of dauricine in a pancreatic cancer BxPC-3 ×enograft animal model and examine the underlying molecular mechanisms through Hh signaling pathway. High-and low-dose dauricine treatment significantly suppressed tumor growth with no concomitant effect on the spleen index. In addition, dauricine induced apoptosis and cell cycle arrest in pancreatic cancer BxPC-3 cells. The inhibitory effects of dauricine on pancreatic cancer may be mediated by the suppression of the Hh signaling pathway, as indicated by the decreases in the gene and protein expression levels of Shh, Ptch1, Smo and Gli1. The effects of dauricine were similar to those of 5-fluorouracil. Dauricine, a naturally occurring alkaloid, may be a potential anticancer agent for the treatment of pancreatic cancer.

Downregulation of sonic hedgehog signaling in the hippocampus leads to neuronal apoptosis in high-fat diet-fed mice

Background/aimsObesity induces hippocampal neuronal apoptosis and leads to cognitive function deficits. Sonic hedgehog (SHH) signaling is crucial during nervous system development and is neuroprotective in many neurologic diseases. This study assessed the role of SHH signaling in the cognitive deficits in high-fat diet (HFD)-induced obese mice. MethodsFlow cytometry assay was used to examine cell apoptosis. Tissue pathology was evaluated by Nissl staining. Immunofluorescent staining and western blotting were used to detect SHH signaling molecules and apoptosis-related proteins. The Morris water maze test was performed to evaluate mouse spatial learning and memory. ResultsAfter HFD feeding for 24 weeks, the expression of SHH signaling molecules was downregulated in the mouse hippocampus. In vitro, GANT61 inhibited SHH signaling and induced apoptosis in HT22 mouse hippocampal cells. Smoothened agonist (SAG), an agonist of SHH signaling, reduced apoptosis in GANT61-treated HT22 cells by regulating caspase-9 and caspase-3 activation. In vivo, 12-week SAG treatment also inhibited the apoptosis of hippocampal neurons in HFD-fed mice by increasing mitofusin 2 (Mfn2) and B-cell lymphoma 2 (Bcl-2) levels and decreasing dynamin-related protein 1 (Drp1) and Bcl-2 homologous antagonist/killer (Bak) levels. Behavioral testing showed that SAG administration ameliorated the cognitive impairment in HFD-fed mice. ConclusionDownregulation of hippocampal SHH signaling leads to neuronal apoptosis and cognitive deficits in HFD-fed mice. These findings provide useful information for the identification of potential targets for research and therapeutic interventions for cognitive impairment in obesity.

Essential Role of IFT140 in Promoting Dentinogenesis

Primary cilia, with highly regulated cellular sensory functions, play key roles in tissue development and function maintenance. Intraflagellar transport 140 (IFT140) is a subunit of IFT complex A, which is specialized for retrograde transportation in cilia. Mutations of Ift140 are usually associated with syndromic ciliopathy and may cause isolated diseases such as retinal dystrophy, short ribs, and polycystic kidney. However, the role of IFT140 in tooth development has not been well investigated. In this study, a close relationship between IFT140 and dentin formation is disclosed. During tooth development, IFT140 was highly expressed in odontoblasts. To further understand the role of IFT140 in dentinogenesis, Ift140flox/flox/Osx-Cre mouse was generated. The dentin thickness of Ift140flox/flox/Osx-Cre mouse is thinner and the dentin formation is slower than that in control. In vitro, deletion of IFT140 in odontoblasts led to poor odontogenic differentiation, abnormal primary cilia, and decreased Sonic hedgehog signaling molecules. More important, due to loss of primary cilia in odontoblasts by IFT140 deletion, reparative dentin formation was impaired in a tooth-drilling model. These results suggest that cilia gene IFT140 is essential in promoting dentin formation and reparation.

A rare case of monozygotic iniodymic diprosopiasis in a German Holstein calf.

Craniofacial duplication abnormity is a rare phenomenon in buiatric practice. This report attends to a male German Holstein calf which could be classified as a diprosopic iniodymus. A fetus exhibiting a doubled face was delivered after fetotomy. To our knowledge, this is the first description of diprosopiasis with two cranial cavities as well as two separate encephala in a calf showing the potential extent of duplication. Throughout this work also the question is answered of whether this malformation in a bovine species arose from one embryo or rather, there is a dizygotic background by genotyping of tissue samples from both parts of the diprosopus. Regarding etiology, not only hereditary dispositions including among others a failed function of the signaling molecule Sonic hedgehog mediating regulation of craniofacial morphogenesis, but also incompletely separated monozygotic twins are discussed.

Effect of purmorphamine on the mRNA expression of Sonic Hedgehog signaling downstream molecules in ovine embryo

Abstract. Sonic Hedgehog (SHH) is a signaling pathway mediated through a receptor system which seems to have effects on oocyte maturation and embryonic development. Purmorphamine is an SHH agonist that performs a crucial role in the regulation of the activity of SHH receptors and downstream transcription factors. The aim of this study was to analyze the effect of purmorphamine on the mRNA expression of SHH signaling downstream molecules (Patched1, Glioma-Associated Oncogene1, Smoothened, Histone Deacetylase1, Histone Deacetylase2 and Histone Deacetylase3) in ovine two-cell embryo. Ovaries were obtained from a slaughterhouse, and cumulus–oocyte complexes were aspirated and cultured in maturation media containing 0, 250 or 500 ng mL−1 purmorphamine. Then, oocytes were fertilized and cultured in a CR1 culture medium and after 24 h, two-cell embryos were collected for RNA extraction. Gene expression was evaluated by real-time polymerase chain reaction (PCR). Results indicated that in 250 ng mL−1 purmorphamine, Smo, Ptch1 and Hdac3 expression reduced, Hdac1 expression increased, and Gli1 and Hdac2 expression levels did not change. In 500 ng mL−1 purmorphamine, Gli1 and Smo transcripts increased, while Ptch1, Hdac2 and Hdac3 transcripts decreased. Regarding to the presence of SHH signaling molecules in two-cell embryos and their response to purmorphamine, it can be suggested that SHH signaling is probably active before embryonic genome activation in ovine embryos.

Effect of Substance P on type II alveolar epithelial cells exposed to hyperoxia and its regulation of the Sonic hedgehog signaling pathway.

Oxidative stress injury and cell death in alveolar epithelial cells may lead to abnormal repair, further resulting in acute and chronic pulmonary diseases. Substance P (SP) has multiple biological activities. The Sonic hedgehog (SHH) pathway is important in lung development and decreasing epithelial injury. To investigate the effects of SP on alveolar epithelial type II cells (AEC IIs), AEC IIs were exposed to 95% oxygen and the SHH signaling pathway was examined. Primary AEC IIs were isolated and purified from premature rats. The cells were divided into four groups: The air (21% oxygen) group, hyperoxia (95% oxygen) group, hyperoxia + SP group and hyperoxia + SP + L703.606 group. The activity of AEC IIs was examined using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay. The apoptotic rate of AEC IIs was analyzed by flow cytometry. The oxidative damage was evaluated by flow cytometry and reactive oxygen species (ROS) were detected using a 2',7'‑dichlorodihydrofluorescein diacetate probe. Quantitative polymerase chain reaction and western blotting were used to detect the mRNA and protein expression of the SHH signaling molecule Smoothened (SMO). The results demonstrated that exposure to 95% oxygen for 24 h significantly increased the level of ROS, contributed to apoptosis and markedly decreased the proliferation of AEC IIs. Compared with hyperoxia exposure, SP treatment decreased the level of ROS, reduced AEC II apoptosis and improved the cell survival sequentially. SMO was found to be expressed in AEC IIs and its expression increased when the cells were in hyperoxic conditions. These effects were enhanced by treatment with SP, which was able to significantly increase the expression of SMO. The aforementioned protective effect was weakened following treatment with L703.606. These findings suggested that SP was a protective regulatory factor that was able to decrease the hyperoxia‑induced cell injury and death, and improve the survival of AEC IIs exposed to hyperoxia, which may be associated with the activation of the SHH signaling pathway.

Auditory ganglion source of Sonic hedgehog regulates timing of cell cycle exit and differentiation of mammalian cochlear hair cells

Neural precursor cells of the central nervous system undergo successive temporal waves of terminal division, each of which is soon followed by the onset of cell differentiation. The organ of Corti in the mammalian cochlea develops differently, such that precursors at the apex are the first to exit from the cell cycle but the last to begin differentiating as mechanosensory hair cells. Using a tissue-specific knockout approach in mice, we show that this unique temporal pattern of sensory cell development requires that the adjacent auditory (spiral) ganglion serve as a source of the signaling molecule Sonic hedgehog (Shh). In the absence of this signaling, the cochlear duct is shortened, sensory hair cell precursors exit from the cell cycle prematurely, and hair cell differentiation closely follows cell cycle exit in a similar apical-to-basal direction. The dynamic relationship between the restriction of Shh expression in the developing spiral ganglion and its proximity to regions of the growing cochlear duct dictates the timing of terminal mitosis of hair cell precursors and their subsequent differentiation.

Anti-apoptotic role of the sonic hedgehog signaling pathway in the proliferation of ameloblastoma

Sonic hedgehog (SHH) signaling pathway is crucial to growth and patterning during organogenesis. Aberrant activation of the SHH signaling pathway can result in tumor formation. We examined the expression of SHH signaling molecules and investigated the involvement of the SHH pathway in the proliferation of ameloblastoma, the most common benign tumor of the jaws. We used immunohistochemistry on ameloblastoma specimens and immunocytochemistry and reverse transcription-PCR on the ameloblastoma cell line AM-1. We also used the inhibitors of SHH signaling, SHH neutralizing antibody and cyclopamine, to assess the effects of SHH on the proliferation of AM-1 cells. We detected expression of SHH, patched, GLI1, GLI2 and GLI3 in the ameloblastoma specimens and AM-1 cells. The proliferation of these cells was significantly inhibited in the presence of SHH neutralizing antibody or cyclopamine; this was confirmed by BrdU incorporation assays. Furthermore, in the presence of SHH neutralizing antibody, nuclear translocation of GLI1 and GLI2 was abolished, apoptosis was induced, BCL-2 expression decreased and BAX expression increased. Our results suggest that the SHH signaling pathway is constitutively active in ameloblastoma and plays an anti-apoptotic role in the proliferation of ameloblastoma cells through autocrine loop stimulation.

Expression of SHH signaling molecules in the developing human primary dentition

BackgroundOur current knowledge on tooth development derives primarily from studies in mice. Very little is known about gene expression and function during human odontogenesis. Sonic Hedgehog (SHH) signaling has been demonstrated to play crucial roles in the development of multiple organs in mice, including the tooth. However, if SHH signaling molecules are expressed and function in the developing human embryonic tooth remain unknown.ResultsWe conducted microarray assay to reveal the expression profile of SHH signaling pathway molecules. We then used in situ hybridization to validate and reveal spatial and temporal expression patterns of a number of selected molecules, including SHH, PTC1, SMO, GLI1, GLI2, and GLI3, in the developing human embryonic tooth germs, and compared them with that in mice. We found that all these genes exhibit similar but slightly distinct expression patterns in the human and mouse tooth germ at the cap and bell stages.ConclusionsOur results demonstrate the operation of active SHH signaling in the developing human tooth and suggest a conserved function of SHH signaling pathway during human odontogenesis.