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Stromal Hedgehog Signaling Drives Segment-Specific Malignant Transformation of Gastrointestinal Stem Cells by Producing Bone Morphogenetic Protein Antagonists.

BACKGROUND & AIMS: Hedgehog signaling plays a complex role in epithelial-stromal interactions, but its effects on gastrointestinal stem cells mediated by heterogeneous stromal cell populations remain incompletely defined. Here, we investigate how stromal Hedgehog signaling regulates gastric stem cells and tumorigenesis in a segment-specific manner. METHODS: We genetically activated Hedgehog signaling in distinct stromal cell lineages using Col1a2-, Pdgfra-, Gli1-, Acta2-, and Prrx1-CreERT mouse lines, combined with lineage tracing, RNA sequencing, chromatin immunoprecipitation-quantitative polymerase chain reaction, and pharmacologic interventions. Human gastric cancer data from The Cancer Genome Atlas were also analyzed. RESULTS: We show that genetic activation of Hedgehog signaling in stromal cells marked by Col1a2, Pdgfra, or Gli1, but not by Acta2, induces tumorigenesis in the stomach and gastroesophageal junction, but not in the small or large intestine. Hedgehog signaling increases the expression of multiple bone morphogenetic protein antagonists in gastric but not colonic stromal cells, via Gli1-mediated transcription. These bone morphogenetic protein antagonists, in turn, activate Wnt/β-catenin signaling in gastric stem cells, driving their proliferation and initiating gastric cancer expressing CD44 and Sox9, but not Lgr5. Activating bone morphogenetic protein or inhibiting Wnt signaling blocks tumor initiation. Analysis of patient data from The Cancer Genome Atlas reveals elevated Hedgehog signaling in gastric cancers, which correlates with suppressed bone morphogenetic protein signaling. CONCLUSIONS: These findings uncover a gastrointestinal segment-specific oncogenic role for Hedgehog signaling in Col1a2+Acta2- stromal cells, mediated through the bone morphogenetic protein-Wnt-β-catenin axis.

BMP Antagonists

Genomic landscape of hepatocellular carcinoma in Egyptian patients by whole exome sequencing.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Chronic hepatitis and liver cirrhosis lead to accumulation of genetic alterations driving HCC pathogenesis. This study is designed to explore genomic landscape of HCC in Egyptian patients by whole exome sequencing. METHODS: Whole exome sequencing using Ion Torrent was done on 13 HCC patients, who underwent surgical intervention (7 patients underwent living donor liver transplantation (LDLT) and 6 patients had surgical resection}. RESULTS: Mutational signature was mostly S1, S5, S6, and S12 in HCC. Analysis of highly mutated genes in both HCC and Non-HCC revealed the presence of highly mutated genes in HCC (AHNAK2, MUC6, MUC16, TTN, ZNF17, FLG, MUC12, OBSCN, PDE4DIP, MUC5b, and HYDIN). Among the 26 significantly mutated HCC genes-identified across 10 genome sequencing studies-in addition to TCGA, APOB and RP1L1 showed the highest number of mutations in both HCC and Non-HCC tissues. Tier 1, Tier 2 variants in TCGA SMGs in HCC and Non-HCC (TP53, PIK3CA, CDKN2A, and BAP1). Cancer Genome Landscape analysis revealed Tier 1 and Tier 2 variants in HCC (MSH2) and in Non-HCC (KMT2D and ATM). For KEGG analysis, the significantly annotated clusters in HCC were Notch signaling, Wnt signaling, PI3K-AKT pathway, Hippo signaling, Apelin signaling, Hedgehog (Hh) signaling, and MAPK signaling, in addition to ECM-receptor interaction, focal adhesion, and calcium signaling. Tier 1 and Tier 2 variants KIT, KMT2D, NOTCH1, KMT2C, PIK3CA, KIT, SMARCA4, ATM, PTEN, MSH2, and PTCH1 were low frequency variants in both HCC and Non-HCC. CONCLUSION: Our results are in accordance with previous studies in HCC regarding highly mutated genes, TCGA and specifically enriched pathways in HCC. Analysis for clinical interpretation of variants revealed the presence of Tier 1 and Tier 2 variants that represent potential clinically actionable targets. The use of sequencing techniques to detect structural variants and novel techniques as single cell sequencing together with multiomics transcriptomics, metagenomics will integrate the molecular pathogenesis of HCC in Egyptian patients.

Humans

Novel Protein-Altering Variants in Cleft Genes Transmitted in Families With NSCL±P.

BACKGROUND: Pathogenic protein-altering variants play a role in the etiology of nonsyndromic cleft lip with or without palate (nsCL±P), one of the most common craniofacial anomalies. However, the genetic basis of many cases remains unclear, complicating risk prediction for affected families. PURPOSE: This study utilized whole-genome sequencing (WGS) of 150 case-families with nsCL±P from sub-Saharan Africa to identify pathogenic risk variants. STUDY DESIGN, SETTING, SAMPLE: This study utilized whole-genome sequencing (WGS) of 150 case-families with nsCL±P from sub-Saharan Africa to identify risk variants. PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE: Genetic variants. MAIN OUTCOME VARIABLES: Nonsyndromic cleft lip with or without palate (nsCL±P). ANALYSES: Genomes were sequenced at a mean ×30 coverage, and variants were prioritized using CADD (≥20), REVEL (≥0.5), and ACMG/AMP clinical significance criteria. RESULTS: We identified pathogenic protein-altering variants in CHD7 (p.Arg1345His), LRP2 (p.Asp3245Asn), RYR1 (p.Arg2163Leu, p.Pro2903Thr), SHH (p.Met114Val), and WNT3 (p.Ser112Pro) highlighting the role of hedgehog signaling pathway (FDR=5.32e-12) in nsCL±P. These variants were inherited from unaffected parents suggesting an incomplete penetrance of the variant effect. Although mouse data showed that knockout of these genes produces cleft phenotypes, in vivo studies will help us better understand how the consequences of these variants differ from benign mutations. The presence of these protein-altering variants in unaffected parents-incomplete penetrance, provides additional evidence supporting the trait complexity. CONCLUSIONS AND RELEVANCE: This study identified rare, pathogenic protein-altering variants in genes involved in key developmental pathways in African families affected by nsCL±P. These findings highlight the critical role of the hedgehog signaling pathway and related networks in the etiology of nsCL±P. These findings underscore the importance of whole-genome sequencing in genetically diverse populations to uncover novel risk variants. These findings enhance our understanding of the genetic etiology of nsCL±P, particularly in under-represented African populations and support the multifactorial inheritance and the involvement of developmental pathways, such as hedgehog signaling in the etiology of clefting.

Humans

Sharp cell type boundaries emerge from coordinated morphogen signaling.

Classic models of the French flag problem depict sharp cell type boundaries emerging from threshold responses to morphogen gradients. How discrete cell type boundaries arise from morphogen signals that vary continuously across developing tissues remains incompletely understood. We use hair follicle dermal condensate (DC) formation to study a sharp developmental transition in which proliferative progenitors undergo cell cycle exit concurrent with molecular differentiation. Using genetic and genomic approaches, we show that Wnt and Hedgehog signaling coordinate separable cellular events during DC commitment. Elevated Wnt signaling promotes cell cycle exit through reduced chromatin binding of the Hedgehog mediator GLI3, while Hedgehog signaling induces differentiation genes in a Wnt-dependent manner and simultaneously elevates Wnt activity. When these responses coincide, differentiation and cell cycle exit occur together, limiting the duration and abundance of intermediate states and producing a sharp boundary. When they do not, intermediate states persist and expand, producing a graded boundary. Thus, a sharp boundary can emerge from a continuous transition that is compressed in time and space.

Hedgehog

Comparative analysis of conserved non-coding elements identifies gene regulatory networks rewired during the water-to-land transition in vertebrates.

The conquest of land by vertebrates has been a pivotal moment in evolutionary history. Adapting to the new habitats necessitated numerous changes in vertebrate anatomy and physiology, creating an enduring imprint on the developmental gene regulatory networks (GRNs) of tetrapods. The increase of high-quality genomic resources over the past decade has made it possible to study the genomic legacy of the water-to-land transition. While much attention has been given to the highly conserved non-coding elements (CNEs) of the genome that share high levels of similarity across evolutionarily diverged clades, recent evidence suggests that perhaps comparable attention should be given to "missing" CNE-s, conserved sequence patches present in extant stem gnathostomes and actinopterygian fishes that have become undetectable in tetrapods during the adaptation to terrestrial life, whether through true sequence loss or divergence beyond alignability. These sequences could help us reveal the relaxation of certain developmental constraints, related to the aquatic lifestyle, that made reaching new adaptive peaks in the developmental landscape possible. In this paper, we search for such CNEs and characterize them in comparison with pan-Gnathostome CNEs, using the zebrafish (Danio rerio) genome as a reference. Our results suggest that the rewiring of developmental networks related to pigmentation and muscle structure formation has left the largest genomic imprint. We also find that components of canonical Wnt and Hedgehog signalling, are enriched among CNEs retained in fish.

cis-regulatory evolution

A single-nucleus transcriptomic atlas of human inner ear development.

Hearing and balance rely on coordinated activity of multiple inner ear cell types, yet the mechanisms governing their development and specification in humans remain unclear. Consequently, this limits our understanding of how disease genes affect cell type formation and function, limiting the development of targeted treatments, including gene therapies. Here we present the Human Inner Ear Development snRNA-seq Atlas (HIEDRA), a single-nucleus transcriptomic atlas of the human inner ear spanning the first and second trimesters. HIEDRA maps sensory and nonsensory epithelia, neurons and mesenchyme-associated populations, including undercharacterized secretory cells required for ion homeostasis. We identify selective vulnerability in sensory and secretory lineages to disease-associated genes, infer regulatory networks and show that Hedgehog signaling suppression is required for secretory cell specification. We validate this mechanism in human inner ear organoids, expanding the model to include all major cell types. Altogether, these findings provide insights into human inner ear cell type specification, improve in vitro models and establish HIEDRA as a resource for investigating human inner ear development.

Journal Article

A conserved molecular logic for neurogenesis to gliogenesis switch in the cerebral cortex.

During development, neural stem cells in the cerebral cortex, also known as radial glial cells (RGCs), generate excitatory neurons, followed by production of cortical macroglia and inhibitory neurons that migrate to the olfactory bulb (OB). Understanding the mechanisms for this lineage switch is fundamental for unraveling how proper numbers of diverse neuronal and glial cell types are controlled. We and others recently showed that Sonic Hedgehog (Shh) signaling promotes the cortical RGC lineage switch to generate cortical oligodendrocytes and OB interneurons. During this process, cortical RGCs generate intermediate progenitor cells that express critical gliogenesis genes Ascl1, Egfr, and Olig2. The increased Ascl1 expression and appearance of Egfr+ and Olig2+ cortical progenitors are concurrent with the switch from excitatory neurogenesis to gliogenesis and OB interneuron neurogenesis in the cortex. While Shh signaling promotes Olig2 expression in the developing spinal cord, the exact mechanism for this transcriptional regulation is not known. Furthermore, the transcriptional regulation of Olig2 and Egfr has not been explored. Here, we show that in cortical progenitor cells, multiple regulatory programs, including Pax6 and Gli3, prevent precocious expression of Olig2, a gene essential for production of cortical oligodendrocytes and astrocytes. We identify multiple enhancers that control Olig2 expression in cortical progenitors and show that the mechanisms for regulating Olig2 expression are conserved between the mouse and human. Our study reveals evolutionarily conserved regulatory logic controlling the lineage switch of cortical neural stem cells.

Animals

Secretion and localized transcription suggest a role in positional signaling for products of the segmentation gene hedgehog.

The segment polarity genes engrailed and wingless are expressed in neighboring stripes of cells on opposite sides of the Drosophila parasegment boundary. Each gene is mutually required for maintenance of the other's expression; continued expression of both also requires several other segment polarity genes. We show here that one such gene, hedgehog, encodes a protein targeted to the secretory pathway and is expressed coincidently with engrailed in embryos and in imaginal discs; maintenance of the hedgehog expression pattern is itself dependent upon other segment polarity genes including engrailed and wingless. Expression of hedgehog thus functions in, and is sensitive to, positional signaling. These properties are consistent with the non-cell autonomous requirement for hedgehog in cuticular patterning and in maintenance of wingless expression.

Amino Acid Sequence

Mechanistic trade-offs between local and long-range signaling activity in natural and synthetic morphogens.

Hedgehog family morphogens present an interesting paradox: Despite being hydrophobic because of dual-lipid modifications, they form spatial concentration gradients that are highly conserved and essential for many aspects of metazoan development. Using live-cell single-molecule tracking and engineered synthetic signaling ligands, we isolated the distinct contribution of each lipid modification to Hedgehog diffusion and signaling potency. We found that although both lipid modifications enhance signaling potency, they do so through different mechanisms. Palmitate directly promotes receptor engagement, whereas cholesterol topologically confines secreted morphogens on the cell surface, effectively using the lipid membrane as a nonsignaling co-receptor that enriches ligands locally at the cost of restricting long-range diffusion. Our results on the function of cholesterol point to an intrinsic trade-off between signaling potency and gradient formation, with implications for the evolution and mechanism of nonsignaling co-receptors.

Signal Transduction

Proteome Unravels Mechanism Differences in Embryogenesis Between Honey Bee Drone and Worker (Apis mellifera L.).

The physiological and social behaviors differ widely between honeybee workers and drones. All the organ rudiments of adult bees are formed during the embryonic stage. The initial molecular bases at the proteomic level for both embryonic developments have been identified, but a comprehensive understanding of the significant events involved in embryonic establishment remains elusive. To elucidate the molecular regulatory mechanisms underlying tissue differentiation during the embryogenesis of drones and workers, we implemented a state-of-the-art approach that combines in-hive inspection and targeted sampling (at nine embryogenesis stages) with high-throughput proteomics technology to investigate the developmental differences. In-hive inspection of hatching timing revealed an average developmental gap of approximately 3.6 h between the two embryos. Furthermore, proteomic analyses indicate that drone and worker embryos adopt distinct developmental strategies. Notably, proteins involved in fatty acid metabolism and key biological pathways related to organ formation-such as the Hedgehog and Wnt signaling pathways-are activated earlier in drones, suggesting that tissue development begins sooner in drone embryos than in workers. Additionally, the upregulation of cytoskeletal proteins and antioxidants in drone embryos likely supports their larger cell size and higher metabolic stress, reflecting distinct molecular characteristics of male development. Ribosomal proteins essential for biosynthetic support remain consistently expressed throughout the late stages in male embryos, indicating that drone embryogenesis lasts longer than that of workers. This work provides novel insights into the molecular foundations of honeybee embryogenesis and lays both theoretical and practical groundwork for future research into the mechanisms driving embryonic development.

Animals

Tumoral switch in NUMB splicing changes essential transcription pathways and induces malignant properties in tumour cells.

BACKGROUND: Emerging evidence indicates that cancer is associated with widespread splicing alterations that generate tumour-specific isoforms. One example is NUMB, an evolutionarily conserved adaptor protein, which produces four isoforms (p72, p71, p66, and p65) through alternative splicing of exons 3 and 9. Although traditionally considered as a tumour suppressor, NUMB has also been reported as an oncogene. We propose that this dual role reflects isoform-specific expression. RESULTS: Using public databases, we identify a tumour-associated switch in NUMB isoform expression: p72 and p71 are upregulated in tumours, whereas p66 and p65 are more highly expressed in non-tumour tissues. These isoforms show distinct associations with key cellular processes. NUMBL, a NUMB homolog, displays expression patterns similar to p65. We further identify two transcriptional clusters: one characterised by high expression of p72 and p71, and the other by enhanced p66/p65/NUMBL expression. These clusters exhibit differential associations with Notch, WNT/β-catenin, Hedgehog, and Hippo signalling pathways, suggesting isoform-specific regulatory roles. In breast cancer cell lines, we develop a NUMB-score based on isoform expression, which classifies cell lines into biologically distinct groups. The p72/p71-enriched group shows distinct signatures, pathway activity, and drug sensitivity. Application of this score to TCGA-BRCA samples reveals a significant link between high NUMB-score and poor survival, as confirmed by Kaplan-Meier analysis. CONCLUSIONS: We find that NUMB emerges as a potential oncogenic contributor and biomarker in the context of splicing-based precision oncology, highlighting Isoform-specific expression as a clinical determinant of tumour behaviour, pathway activity, and therapeutic response.

Humans

Rewiring Cellular Context as A Central Mechanism Governing Cancer Stem Cell Survival: Insights from ESC Comparisons.

Cancer stem cells (CSCs) drive tumor initiation, metastasis, and therapy resistance, yet their remarkable persistence remains poorly understood. While CSCs share stemness attributes with embryonic stem cells (ESCs), including self-renewal, transcriptional plasticity, and permissive chromatin, they exhibit a fundamentally divergent regulatory logic that prioritizes survival over developmental fidelity. ESCs maintain globally open chromatin that supports transcriptional hyperactivity but predisposes them to apoptosis under genotoxic stress, whereas CSCs maintain dynamically inducible, permissive chromatin at survival loci while repressing differentiation programs, enabling adaptive stress responses. We advance the hypothesis that CSC persistence emerges not from any single factor, but from the integrative rewiring of signaling cascades (Wnt/β-catenin, Notch, Hedgehog, PI3K/AKT/mTOR), stress-responsive transcription factors (HIFs, NF-κB, STAT3), and core pluripotency networks (OCT4, SOX2, NANOG) within a survival-centric context, reinforced by dynamic chromatin remodeling, inducible super-enhancer landscapes, and microenvironmental cues (hypoxia, inflammation, matrix stiffness). Within this framework, the E2F family serves as a key contextual integrator: in ESCs, constitutive E2F activity triggers p53-mediated apoptosis upon DNA damage, preserving genomic integrity; in CSCs, deregulated E2F activity redirects transcription toward DNA repair, antioxidant defenses, and anti-apoptotic programs. This functional divergence underscores that phenotypic outcome is determined by the broader cellular and epigenetic landscape rather than any single factor. We conclude that CSC persistence is an emergent property of this integrated, survival-centric program, fundamentally distinct from the developmental imperative of ESCs. Effective therapeutic strategies must therefore move beyond targeting individual pathways to dismantle the interconnected regulatory networks that define the CSC survival context, offering a more robust approach to overcome therapy resistance and prevent tumor relapse.

Cancer Stem Cells (CSCs)

Defective EV-mediated transport of SHH alters neural fate specification in EPM1 epilepsy.

The extracellular milieu, including extracellular vesicles (EVs), plays a pivotal role in brain development. In this study, we sought to elucidate the pathogenesis of progressive myoclonus epilepsy type 1 (EPM1), a disease caused by mutations in the CSTB gene, using cerebral organoids (COs) derived from patient cells. The results demonstrate that EPM1 COs display increased electrophysiological activity and disrupted excitatory/inhibitory (E/I) balance. Single-cell RNA sequencing analysis of ventral EPM1-COs revealed an abnormal specification of progenitor fate, with a shift toward dorsal neuron identities. We demonstrated that this misspecification is driven by a functional alteration of the ventral signaling niche, resulting from impaired EV dynamics and altered protein cargo. Mechanistically, we identified Sonic Hedgehog (SHH) as a direct physical interactor of CSTB and demonstrated that CSTB deficiency leads to reduced SHH content and secretion. Our findings establish CSTB as a safeguard of ventral patterning and identify the CSTB-SHH-EV axis as a potential therapeutic target for mitigating the E/I imbalance associated with EPM1.

Hedgehog Proteins

Clinical implication of transcriptional dysregulation in the SHH-GLI pathway involving the GLI1 rs61739569 (T>C) variant toward chronic obstructive pulmonary disease (COPD) in North Indians.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) ranks among the leading causes of morbidity and mortality globally. Genomic susceptibility factors are acknowledged as critical modulators of disease variability and progression. The Sonic Hedgehog (SHH) pathway regulates epithelial tissue healing, mucin synthesis, and airway remodeling. GLI1 polymorphic variants may influence the manifestations of COPD. METHODOLOGY: A case-control study was conducted, involving 500 patients with COPD and 500 controls from the North Indian population. We genotyped two GLI1 polymorphisms (rs61739569 (T>C) and rs2228226 (G>C). Logistic regression models were applied to examine the associations between COPD susceptibility and clinical features. RESULTS: rs61739569 and rs2228226 show no association with an increased risk of COPD overall. Nonetheless, rs61739569 exhibited significant phenotype-specific correlations: individuals possessing the CC genotype demonstrated a markedly elevated risk of chronic cough, sputum production, and exacerbations, while displaying a diminished risk of dyspnea and activity limitation. CONCLUSION: Variations in GLI1 may influence the symptoms of COPD, rather than the overall likelihood of developing COPD. The rs61739569 is particularly applicable to mucus-dominant phenotypes, such as those resembling chronic bronchitis. This study suggests that GLI1 signaling exhibits context-dependent functional significance in COPD.

Humans

Alternative spliceosomal protein Eftud2 mediated Kif3a exon skipping promotes SHH-subgroup medulloblastoma progression.

Alternative splicing plays a pivotal role in various facets of organogenesis, immune response, and tumorigenesis. Medulloblastoma represents a prevalent childhood brain tumor, with approximately one-third classified as the Sonic Hedgehog (SHH) subgroup. Nevertheless, the contribution of alternative splicing to medulloblastoma oncogenesis remains elusive. This investigation delineated an upregulation of the spliceosomal protein Eftud2 in the SHH-subgroup medulloblastoma mouse model and human medulloblastoma patients. Targeted ablation of Eftud2 in granule precursor cells (GNPs) within the cerebellum prolonged the survival of SHH-subgroup medulloblastoma mice, indicating a putative association between Eftud2 expression and medulloblastoma prognosis. Functional assays unveiled that EFTUD2 depletion in human medulloblastoma cells significantly curtailed cellular proliferation by impeding the activation of the SHH signaling pathway. Through multi-omics sequencing analysis, it was discerned that Eftud2 influences exons 10-11 skipping of Kif3a, a kinesin motor critical for primary cilia formation. Notably, exons 10-11 skipping in Kif3a augmented human medulloblastoma cell proliferation by potentiating the transcriptional activity of Gli2. These findings underscore a robust correlation between Eftud2 and SHH-subgroup medulloblastoma, emphasizing its regulatory role in modulating downstream transcription factors through the alternative splicing of pivotal genes within the SHH signaling pathway, thereby propelling the aggressive proliferation of SHH-subgroup medulloblastoma.

Medulloblastoma