CPLANE protein INTU regulates growth and patterning of the mouse lungs through cilia-dependent Hh signaling.

Congenital lung malformations are fatal at birth in their severe forms. Prevention and early intervention of these birth defects require a comprehensive understanding of the molecular mechanisms of lung development. We find that the loss of inturned (Intu), a cilia and planar polarity effector gene, severely disrupts growth and branching morphogenesis of the mouse embryonic lungs. Consistent with our previous results indicating an important role for Intu in ciliogenesis and hedgehog (Hh) signaling, we find greatly reduced number of primary cilia in both the epithelial and mesenchymal tissues of the lungs. We also find significantly reduced expression of Gli1 and Ptch1, direct targets of Hh signaling, suggesting disruption of cilia-dependent Hh signaling in Intu mutant lungs. An agonist of the Hh pathway activator, smoothened, increases Hh target gene expression and tubulogenesis in explanted wild type, but not Intu mutant, lungs, suggesting impaired Hh signaling response underlying lung morphogenetic defects in Intu mutants. Furthermore, removing both Gli2 and Intu completely abolishes branching morphogenesis of the lung, strongly supporting a mechanism by which Intu regulates lung growth and patterning through cilia-dependent Hh signaling. Moreover, a transcriptomics analysis identifies around 200 differentially expressed genes (DEGs) in Intu mutant lungs, including known Hh target genes Gli1, Ptch1/2 and Hhip. Genes involved in muscle differentiation and function are highly enriched among the DEGs, consistent with an important role of Hh signaling in airway smooth muscle differentiation. In addition, we find that the difference in gene expression between the left and right lungs diminishes in Intu mutants, suggesting an important role of Intu in asymmetrical growth and patterning of the mouse lungs.

ZMYND8 Is a Regulator of Sonic Hedgehog Signaling in ATRA-Mediated Differentiation of Neuroblastoma Cells.

Zinc Finger MYND (Myeloid, Nervy, and DEAF-1) type containing 8 (ZMYND8) is a crucial epigenetic regulator that plays a multifaceted role in governing a spectrum of vital cellular processes, encompassing proliferation, apoptosis, migration, tumor suppression, and differentiation. It has emerged as a key player in neuronal differentiation by orchestrating the expression of neuronal lineage-committed genes. The present study uncovers the role of ZMYND8 in regulating the Sonic Hedgehog (SHH) signaling axis, which is crucial for neuronal differentiation. Genetic deletion of ZMYND8 leads to a significant reduction in SHH pathway genes, GLI1, and PTCH1 expression during all-trans-retinoic acid (ATRA)-induced differentiation. ZMYND8 and RNA pol II S5P are found to co-occupy the GLI1 and PTCH1 gene promoters, positively impacting their gene transcription upon ATRA treatment. Interestingly, ZMYND8 is found to counteract the inhibitory effects of Cyclopamine that block the upstream SHH pathway protein SMO, resulting in enhanced neurite formation in neuroblastoma cells following their treatment with ATRA. These results indicate that ZMYND8 is an epigenetic regulator of the SHH signaling pathway and has tremendous therapeutic potential in ATRA-mediated differentiation of neuroblastoma.

Staphylococcal enterotoxin B exposed to pregnant rats inhibits the hedgehog signaling pathway in thymic T lymphocytes of the offspring.

The Hedgehog (Hh) signaling pathway is involved in T cell differentiation and development and plays a major regulatory part in different stages of T cell development. A previous study by us suggested that prenatal exposure to staphylococcal enterotoxin B (SEB) changed the percentages of T cell subpopulation in the offspring thymus. However, it is unclear whether prenatal SEB exposure impacts the Hh signaling pathway in thymic T cells. In the present study, pregnant rats at gestational day 16 were intravenously injected once with 15 µg SEB, and the thymi of both neonatal and adult offspring rats were aseptically acquired to scrutinize the effects of SEB on the Hh signaling pathway. It firstly found that prenatal SEB exposure clearly caused the increased expression of Shh and Dhh ligands of the Hh signaling pathway in thymus tissue of both neonatal and adult offspring rats, but significantly decreased the expression levels of membrane receptors of Ptch1 and Smo, transcription factor Gli1, as well as target genes of CyclinD1, C-myc, and N-myc in Hh signaling pathway of thymic T cells. These data suggest that prenatal SEB exposure inhibits the Hh signaling pathway in thymic T lymphocytes of the neonatal offspring, and this effect can be maintained in adult offspring via the imprinting effect.

Effects of mesenchymal stem cells versus curcumin on sonic hedgehog signaling in experimental model of Hepatocellular Carcinoma.

BACKGROUND: Sonic Hedgehog (SHH) is a fundamental signaling pathway that controls tissue reconstruction, stem cell biology, and differentiation and has a role in gut tissue homeostasis and development. Dysregulation of SHH leads to the development of HCC. METHODS, AND RESULTS: The present study was conducted to compare the effects of mesenchymal stem cells (MSCs) and curcumin on SHH molecular targets in an experimental model of HCC in rats. One hundred rats were divided equally into the following groups: control group, HCC group, HCC group received MSCs, HCC group received curcumin, and HCC group received MSCs and curcumin. Histopathological examinations were performed, and gene expression of SHH signaling target genes (SHH, PTCH1, SMOH, and GLI1) was assessed by real-time PCR in rat liver tissue. Results showed that SHH target genes were significantly upregulated in HCC-untreated rat groups and in MSC-treated groups, with no significant difference between them. Administration of curcumin with or without combined administration of MSCs led to a significant down-regulation of SHH target genes, with no significant differences between both groups. As regards the histopathological examination of liver tissues, both curcumin and MSCs, either through separate use or their combined use, led to a significant restoration of normal liver pathology. CONCLUSIONS: In conclusion, SHH signaling is upregulated in the HCC experimental model. MSCs do not inhibit the upregulated SHH target genes in HCC. Curcumin use with or without MSCs administration led to a significant down-regulation of SHH signaling in HCC and a significant restoration of normal liver pathology.

A Pilot Immunohistochemical Study Identifies Hedgehog Pathway Expression in Sinonasal Adenocarcinoma.

Tumors of the head and neck, more specifically the squamous cell carcinoma, often show upregulation of the Hedgehog signaling pathway. However, almost nothing is known about its role in the sinonasal adenocarcinoma, either in intestinal or non-intestinal subtypes. In this work, we have analyzed immunohistochemical staining of six Hedgehog pathway proteins, sonic Hedgehog (SHH), Indian Hedgehog (IHH), Patched1 (PTCH1), Gli family zinc finger 1 (GLI1), Gli family zinc finger 2 (GLI2), and Gli family zinc finger 3 (GLI3), on 21 samples of sinonasal adenocarcinoma and compared them with six colon adenocarcinoma and three salivary gland tumors, as well as with matching healthy tissue, where available. We have detected GLI2 and PTCH1 in the majority of samples and also GLI1 in a subset of samples, while GLI3 and the ligands SHH and IHH were generally not detected. PTCH1 pattern of staining shows an interesting pattern, where healthy samples are mostly positive in the stromal compartment, while the signal shifts to the tumor compartment in tumors. This, taken together with a stronger signal of GLI2 in tumors compared to non-tumor tissues, suggests that the Hedgehog pathway is indeed activated in sinonasal adenocarcinoma. As Hedgehog pathway inhibitors are being tested in combination with other therapies for head and neck squamous cell carcinoma, this could provide a therapeutic option for patients with sinonasal adenocarcinoma as well.

Ptch1 is essential for cochlear marginal cell differentiation and stria vascularis formation.

A common cause of deafness in humans is dysregulation of the endocochlear potential generated by the stria vascularis (SV). Thus, proper formation of the SV is critical for hearing. Using single-cell transcriptomics and a series of Shh signaling mutants, we discovered that the Shh receptor Patched1 (Ptch1) is essential for marginal cell (MC) differentiation and SV formation. Single-cell RNA sequencing analyses revealed that the cochlear roof epithelium is already specified into discrete domains with distinctive gene expression profiles at embryonic day 14, with Gsc as a marker gene of the MC lineage. Ptch1 deficiency leads to defective specification of MC precursors along the cochlear basal-apical regions. We demonstrated that elevated Gli2 levels impede MC differentiation through sustaining Otx2 expression and maintaining the progenitor state of MC precursors. Our results uncover an early specification of cochlear non-sensory epithelial cells and establish a crucial role of the Ptch1-Gli2 axis in regulating the development of SV.

Applying Spinal Cord Organoids as a quantitative approach to study the mammalian Hedgehog pathway.

The Hedgehog (HH) pathway is crucial for embryonic development, and adult homeostasis. Its dysregulation is implicated in multiple diseases. Existing cellular models used to study HH signal regulation in mammals do not fully recapitulate the complexity of the pathway. Here we show that Spinal Cord Organoids (SCOs) can be applied to quantitively study the activity of the HH pathway. During SCO formation, the specification of different categories of neural progenitors (NPC) depends on the intensity of the HH signal, mirroring the process that occurs during neural tube development. By assessing the number of NPCs within these distinct subgroups, we are able to categorize and quantify the activation level of the HH pathway. We validate this system by measuring the effects of mutating the HH receptor PTCH1 and the impact of HH agonists and antagonists on NPC specification. SCOs represent an accessible and reliable in-vitro tool to quantify HH signaling and investigate the contribution of genetic and chemical cues in the HH pathway regulation.

PTCH1-mutant human cerebellar organoids exhibit altered neural development and recapitulate early medulloblastoma tumorigenesis.

Patched 1 (PTCH1) is the primary receptor for the sonic hedgehog (SHH) ligand and negatively regulates SHH signalling, an essential pathway in human embryogenesis. Loss-of-function mutations in PTCH1 are associated with altered neuronal development and the malignant brain tumour medulloblastoma. As a result of differences between murine and human development, molecular and cellular perturbations that arise from human PTCH1 mutations remain poorly understood. Here, we used cerebellar organoids differentiated from human induced pluripotent stem cells combined with CRISPR/Cas9 gene editing to investigate the earliest molecular and cellular consequences of PTCH1 mutations on human cerebellar development. Our findings demonstrate that developmental mechanisms in cerebellar organoids reflect in vivo processes of regionalisation and SHH signalling, and offer new insights into early pathophysiological events of medulloblastoma tumorigenesis without the use of animal models.

Distinct expression patterns of Hedgehog signaling components in mouse gustatory system during postnatal tongue development and adult homeostasis.

The Hedgehog (HH) pathway regulates embryonic development of anterior tongue taste fungiform papilla (FP) and the posterior circumvallate (CVP) and foliate (FOP) taste papillae. HH signaling also mediates taste organ maintenance and regeneration in adults. However, there are knowledge gaps in HH pathway component expression during postnatal taste organ differentiation and maturation. Importantly, the HH transcriptional effectors GLI1, GLI2 and GLI3 have not been investigated in early postnatal stages; the HH receptors PTCH1, GAS1, CDON and HHIP, required to either drive HH pathway activation or antagonism, also remain unexplored. Using lacZ reporter mouse models, we mapped expression of the HH ligand SHH, HH receptors, and GLI transcription factors in FP, CVP and FOP in early and late postnatal and adult stages. In adults we also studied the soft palate, and the geniculate and trigeminal ganglia, which extend afferent fibers to the anterior tongue. Shh and Gas1 are the only components that were consistently expressed within taste buds of all three papillae and the soft palate. In the first postnatal week, we observed broad expression of HH signaling components in FP and adjacent, non-taste filiform (FILIF) papillae in epithelium or stroma and tongue muscles. Notably, we observed elimination of Gli1 in FILIF and Gas1 in muscles, and downregulation of Ptch1 in lingual epithelium and of Cdon, Gas1 and Hhip in stroma from late postnatal stages. Further, HH receptor expression patterns in CVP and FOP epithelium differed from anterior FP. Among all the components, only known positive regulators of HH signaling, SHH, Ptch1, Gli1 and Gli2, were expressed in the ganglia. Our studies emphasize differential regulation of HH signaling in distinct postnatal developmental periods and in anterior versus posterior taste organs, and lay the foundation for functional studies to understand the roles of numerous HH signaling components in postnatal tongue development.

Numb positively regulates Hedgehog signaling at the ciliary pocket.

Hedgehog (Hh) signaling relies on the primary cilium, a cell surface organelle that serves as a signaling hub for the cell. Using proximity labeling and quantitative proteomics, we identify Numb as a ciliary protein that positively regulates Hh signaling. Numb localizes to the ciliary pocket and acts as an endocytic adaptor to incorporate Ptch1 into clathrin-coated vesicles, thereby promoting Ptch1 exit from the cilium, a key step in Hh signaling activation. Numb loss impedes Sonic hedgehog (Shh)-induced Ptch1 exit from the cilium, resulting in reduced Hh signaling. Numb loss in spinal neural progenitors reduces Shh-induced differentiation into cell fates reliant on high Hh activity. Genetic ablation of Numb in the developing cerebellum impairs the proliferation of granule cell precursors, a Hh-dependent process, resulting in reduced cerebellar size. This study highlights Numb as a regulator of ciliary Ptch1 levels during Hh signal activation and demonstrates the key role of ciliary pocket-mediated endocytosis in cell signaling.

Hedgehog ligand and receptor cooperatively regulate EGFR stability and activity in non-small cell lung cancer.

PURPOSE: The hyperactivation of epidermal growth factor receptor (EGFR) plays a crucial role in non-small cell lung cancer (NSCLC). Hedgehog (Hh) signaling has been implicated in the tumorigenesis and progression of various cancers, however, its function in NSCLC cells remains controversial. Herein, we present a novel finding that challenges the current understanding of Hh signaling in tumor growth. METHODS: Expression of Hh ligands and receptor were assessed using TCGA datasets, immunoblotting and immunohistochemical. Biological function of Hh ligands and receptor in NSCLC were tested using colony formation, cell count kit-8 (CCK-8) and xenograft assays. Biochemical effect of Hh ligands and receptor on regulating EGFR stability and activity were checked via immunoblotting. RESULTS: Expression of Hh ligands and receptor was suppressed in NSCLC tissues, and the lower expression levels of these genes were associated with poor prognosis. Ptch1 binds to EGFR and facilitates its poly-ubiquitylation and degradation independent of downstream transcriptional signaling. Moreover, Hh ligands cooperate with Ptch1 to regulate the protein stability and activity of EGFR. This unique mechanism leads to a suppressive effect on NSCLC tumor growth. CONCLUSION: Non-canonical Hh signaling pathway, involving cooperation between Hh ligands and their receptor Ptch1, facilitates the degradation of EGFR and attenuates its activity in NSCLC. These findings provide novel insights into the regulation of EGFR protein stability and activity, offer new diagnostic indicators for molecular typing of NSCLC and identify potential targets for targeted therapy of this challenging disease.

Impaired Sonic Hedgehog Responsiveness of Induced Pluripotent Stem Cell-Derived Floor Plate Cells Carrying the LRRK2-I1371V Mutation Contributes to the Ontogenic Origin of Lower Dopaminergic Neuron Yield.

Lower population of dopaminergic (DA) neurons is known to increase susceptibility to Parkinson's disease (PD), and our earlier study showed a lower yield of DA neurons in Leucine-Rich Repeat Kinase Isoleucine 1371 Valine (LRRK2-I1371V) mutation-carrying PD patient-derived induced Pluripotent Stem Cells (iPSCs). Although the role of Sonic Hedgehog (SHH) in DA neurogenesis of floor plate cells (FPCs) is known, the effect of LRRK2 mutations on SHH responsiveness of FPCs impacting DA neuronal yield has not been studied. We investigated SHH responsiveness of FPCs derived from LRRK2-I1371V PD patient iPSCs with regard to the expression of SHH receptors Patched1 (Ptch1) and Smoothened (Smo), in conjunction with nuclear Gli1 (glioma-associated oncogene 1) expression, intracellular Ca2+ rise, and cytosolic cyclic adenosine monophosphate (cAMP) levels upon SHH induction. In addition, we examined the mechanistic link with LRRK2-I1371V gain-of-function by assessing membrane fluidity and Rab8A and Rab10 phosphorylation in SH-SY5Y cells and healthy control (HC) FPCs overexpressing LRRK2-I1371V as well as FPCs. Although total expression of Ptch1 and Smo was comparable, receptor expression on cell surface was significantly lower in LRRK2-I1371V FPCs than in HC FPCs, with distinctly lower nuclear expression of the downstream transcription factor Gli1. HC-FPCs transfected with LRRK2-I1371V exhibited a similarly reduced cell surface expression of Ptch1 and Smo. Intracellular Ca2+ response was significantly lower with corresponding elevated cAMP levels in LRRK2-I1371V FPCs compared with HC FPCs upon SHH stimulation. The LRRK2-I1371V mutant FPCs and LRRK2-I1371V-transfected SH-SY5Y and HC FPCs too exhibited higher autophosphorylation of phospho LRRK2 (pLRRK2) serine1292 and serine935, as well as substrate phosphorylation of Rab8A and Rab10. Concurrent increase in membrane fluidity, accompanied by a decrease in membrane cholesterol, and lower expression of lipid raft marker caveolin 1 were also observed in them. These findings suggest that impaired SHH responsiveness of LRRK2-I1371V PD FPCs indeed leads to lower yield of DA neurons during ontogeny. Reduced cell surface expression of SHH receptors is influenced by alteration in membrane fluidity owing to the increased substrate phosphorylation of Rab8A and reduced membrane protein trafficking due to pRab10, both results of the LRRK2-I1371V mutation.

Implicating clinical utility of altered expression of PTCH1 & SMO in oral squamous cell carcinoma.

INTRODUCTION: Oral cancer poses a significant burden on public health in India, with higher incidence and mortality rates. Despite advancements in treatment modalities, prognosis remains poor due to factors such as localized recurrence and lymph node metastasis, potentially influenced by cancer stem cells. Among signaling pathways implicated in CSC regulation, the Hedgehog pathway plays a crucial role in oral squamous cell carcinoma (OSCC). MATERIAL & METHODS: 97 OSCC patients' tissue samples were collected and subjected to RNA isolation, cDNA synthesis and quantitative real-time PCR to analyze PTCH1 and SMO expression. Protein expression was assessed through immunohistochemistry. Clinicopathological parameters were correlated with gene and protein expression. Statistical analysis included Pearson chi-square tests, co-relation co-efficient tests, Kaplan-Meier survival analysis and ROC curve analysis. RESULTS: PTCH1 expression correlated with lymphatic permeation (p = 0.002) and tumor stage (p = 0.002), while SMO expression correlated with lymph node status (p = 0.034) and tumor stage (p = 0.021). PTCH1 gene expression correlated with lymph node status (p = 0.024). High PTCH1 gene expression was associated with shorter survival in tongue cancer patients. ROC curve analysis indicated diagnostic potential for PTCH1 and SMO gene and cytoplasmic SMO expression in distinguishing malignant tissues from adjacent normal tissues. CONCLUSION: PTCH1 and SMO play a crucial role in oral cancer progression, correlating with tumor stages and metastatic potential. Despite not directly influencing overall survival, PTCH1 expression at specific anatomical sites hints at its prognostic implications. PTCH1 and SMO exhibit diagnostic potential, suggesting their utility as molecular markers in oral cancer management and therapeutic strategies.