Essential role of Notch/Hes1 signaling in postnatal pancreatic exocrine development

Expression of nicastrin, NICD1, and Hes1 in NCSTN knockout mice: implications for hidradenitis suppurativa, Alzheimer's, and liver cancer

BACKGROUND

Nicastrin, a subunit of the γ-secretase complex, is encoded by the NCSTN gene and regulates notch signaling, it is involved in the pathogenesis of hidradenitis suppurativa (HS), Alzheimer disease (AD), and liver cancer. However, the animal models for studying HS are relatively scarce.

METHODS

CRISPR/Cas-mediated genetic engineering was used to generate targeted knockout offspring mice (C57BL/6J). Different doses (10 mg/kg, 20 mg/kg, and 30 mg/kg) and injection methods (subcutaneous/intraperitoneal/gavage injection) of tamoxifen were used to induce the construction of NCSTN knockout mice (mice model). The expressions of nicastrin, NICD1, hes1 in skin, brain, and liver tissue in mice model and wild-type (WT) mice were measured by qRT-PCR and IHC.

RESULTS

The construction of mice model was successfully induced by tamoxifen, knockout efficiency was 93%, there was no difference in knockout efficiency among three doses, injection methods, genders (P > 0.05). HS-like lesions appeared on the skin of NCSTN knockout mice after 1 month of treatment with tamoxifen, male mice had a higher number of skin lesions compared to female mice (male vs female = 76.5% vs 41.7%, P = 0.027). Compared with WT mice, the expressions of nicastrin (skin P = 0.0009, brain P = 0.0194, liver P = 0.0066), NICD1 (skin P = 0.0115, brain P = 0.0307, liver P = 0.008), hes1 (skin P = 0.0476, brain P = 0.0143, liver P = 0.0003) in mice model all decreased.

CONCLUSIONS

The NCSTN knockout mouse might be employed as HS animal model; Reducing nicastrin may affect the expression of notch1-hes1 pathway molecules in skin, brain, and liver tissues; low dose (10 mg/kg/d) tamoxifen could be used to induce the deletion of the target gene in mice.

CFTR represses a PDX1 axis to govern pancreatic ductal cell fate

Inflammation, acinar atrophy, and ductal hyperplasia drive pancreatic remodeling in newborn cystic fibrosis (CF) ferrets lacking a functional cystic fibrosis conductance regulator (CFTR) channel. These changes are associated with a transient phase of glucose intolerance that involves islet destruction and subsequent regeneration near hyperplastic ducts. The phenotypic changes in CF ductal epithelium and their impact on islet function are unknown. Using bulk RNA sequencing (RNA-seq), single-cell RNA sequencing (scRNA-seq), and assay for transposase-accessible chromatin using sequencing (ATAC-seq) on CF ferret models, we demonstrate that ductal CFTR protein constrains PDX1 expression by maintaining PTEN and GSK3β activation. In the absence of CFTR protein, centroacinar cells adopted a bipotent progenitor-like state associated with enhanced WNT/β-Catenin, transforming growth factor β (TGF-β), and AKT signaling. We show that the level of CFTR protein, not its channel function, regulates PDX1 expression. Thus, this study has discovered a cell-autonomous CFTR-dependent mechanism by which CFTR mutations that produced little to no protein could impact pancreatic exocrine/endocrine remodeling in people with CF.

An Orthologics Study of the Notch Signaling Pathway

The Notch signaling pathway plays a major role in embryological development and in the ongoing life processes of many animals. Its role is to provide cell-to-cell communication in which a Sender cell, bearing membrane-embedded ligands, instructs a Receiver cell, bearing membrane-embedded receptors, to adopt one of two available fates. Elucidating the evolution of this pathway is the topic of this paper, which uses an orthologs approach, providing a comprehensive basis for the study. Using BLAST searches, orthologs were identified for all the 49 components of the Notch signaling pathway. The historical time course of integration of these proteins, as the animals evolved, was elucidated. Insofar as cell-to-cell communication is of relevance only in multicellular animals, it is not surprising that the Notch system became functional only with the evolutionary appearance of Metazoa, the first multicellular animals. Porifera contributed a quarter of the Notch pathway proteins, the Cnidaria brought the total to one-half, but the system reached completion only when humans appeared. A literature search elucidated the roles of the Notch system's components in modern descendants of the ortholog-contributing ancestors. A single protein, the protein tyrosine kinase (PTK) of the protozoan Ministeria vibrans, was identified as a possible pre-Metazoan ancestor of all three of the Notch pathway proteins, DLL, JAG, and NOTCH. A scenario for the evolution of the Notch signaling pathway is presented and described as the co-option of its components, clade by clade, in a repurposing of genes already present in ancestral unicellular organisms.

Modulating endothelial cell dynamics in fat grafting: the impact of DLL4 siRNA via adipose stem cell extracellular vesicles

In the context of improving the efficacy of autologous fat grafts (AFGs) in reconstructive surgery, this study delineates the novel use of adipose-derived mesenchymal stem cells (ADSCs) and their extracellular vesicles (EVs) as vehicles for delivering delta-like ligand 4 (DLL4) siRNA. The aim was to inhibit DLL4, a gene identified through transcriptome analysis as a critical player in the vascular endothelial cells of AFG tissues, thereby negatively affecting endothelial cell functions and graft survival through the Notch signaling pathway. By engineering ADSC EVs to carry DLL4 siRNA (ADSC EVs-siDLL4), the research demonstrated a marked improvement in endothelial cell proliferation, migration, and lumen formation, and enhanced angiogenesis in vivo, leading to a significant increase in the survival rate of AFGs. This approach presents a significant advancement in the field of tissue engineering and regenerative medicine, offering a potential method to overcome the limitations of current fat grafting techniques.NEW & NOTEWORTHY This study introduces a groundbreaking method for enhancing autologous fat graft survival using adipose-derived stem cell extracellular vesicles (ADSC EVs) to deliver DLL4 siRNA. By targeting the delta-like ligand 4 (DLL4) gene, crucial in endothelial cell dynamics, this innovative approach significantly improves endothelial cell functions and angiogenesis, marking a substantial advancement in tissue engineering and regenerative medicine.

LINC MIR503HG Controls SC-β Cell Differentiation and Insulin Production by Targeting CDH1 and HES1

Stem cell-derived pancreatic progenitors (SC-PPs), as an unlimited source of SC-derived β (SC-β) cells, offers a robust tool for diabetes treatment in stem cell-based transplantation, disease modeling, and drug screening. Whereas, PDX1+/NKX6.1+ PPs enhances the subsequent endocrine lineage specification and gives rise to glucose-responsive SC-β cells in vivo and in vitro. To identify the regulators that promote induction efficiency and cellular function maturation, single-cell RNA-sequencing is performed to decipher the transcriptional landscape during PPs differentiation. The comprehensive evaluation of functionality demonstrated that manipulating LINC MIR503HG using CRISPR in PP cell fate decision can improve insulin synthesis and secretion in mature SC-β cells, without effects on liver lineage specification. Importantly, transplantation of MIR503HG-/- SC-β cells in recipients significantly restored blood glucose homeostasis, accompanied by serum C-peptide release and an increase in body weight. Mechanistically, by releasing CtBP1 occupying the CDH1 and HES1 promoters, the decrease in MIR503HG expression levels provided an excellent extracellular niche and appropriate Notch signaling activation for PPs following differentiation. Furthermore, this exhibited higher crucial transcription factors and mature epithelial markers in CDH1High expressed clusters. Altogether, these findings highlighted MIR503HG as an essential and exclusive PP cell fate specification regulator with promising therapeutic potential for patients with diabetes.

Differential Occupancy and Regulatory Interactions of KDM6A in Bladder Cell Lines

Epigenetic deregulation is a critical theme which needs further investigation in bladder cancer research. One of the most highly mutated genes in bladder cancer is KDM6A, which functions as an H3K27 demethylase and is one of the MLL3/4 complexes. To decipher the role of KDM6A in normal versus tumor settings, we identified the genomic landscape of KDM6A in normal, immortalized, and cancerous bladder cells. Our results showed differential KDM6A occupancy in the genes involved in cell differentiation, chromatin organization, and Notch signaling depending on the cell type and the mutation status of KDM6A. Transcription factor motif analysis revealed HES1 to be enriched at KDM6A peaks identified in the T24 bladder cancer cell line; moreover, it has a truncating mutation in KDM6A and lacks a demethylase domain. Our co-immunoprecipitation experiments revealed TLE co-repressors and HES1 as potential truncated and wild-type KDM6A interactors. With the aid of structural modeling, we explored how truncated KDM6A could interact with TLE and HES1, as well as RUNX and HHEX transcription factors. These structures provide a solid means of studying the functions of KDM6A independently of its demethylase activity. Collectively, our work provides important contributions to the understanding of KDM6A malfunction in bladder cancer.

Context-Dependent Roles of Hes1 in the Adult Pancreas and Pancreatic Tumor Formation

BACKGROUND & AIMS

The Notch signaling pathway is an important pathway in the adult pancreas and in pancreatic ductal adenocarcinoma (PDAC), with hairy and enhancer of split-1 (HES1) as the core molecule in this pathway. However, the roles of HES1 in the adult pancreas and PDAC formation remain controversial.

METHODS

We used genetically engineered dual-recombinase mouse models for inducing Hes1 deletion under various conditions.

RESULTS

The loss of Hes1 expression in the adult pancreas did not induce phenotypic alterations. However, regeneration was impaired after caerulein-induced acute pancreatitis. In a pancreatic intraepithelial neoplasia (PanIN) mouse model, PanINs rarely formed when Hes1 deletion preceded PanIN formation, whereas more PanINs were formed when Hes1 deletion succeeded PanIN formation. In a PDAC mouse model, PDAC formation was also enhanced by Hes1 deletion after PanIN/PDAC development; therefore, Hes1 promotes PanIN initiation but inhibits PanIN/PDAC progression. RNA sequencing and chromatin immunoprecipitation-quantitative polymerase chain reaction revealed that Hes1 deletion enhanced epithelial-to-mesenchymal transition via Muc5ac up-regulation in PDAC progression. The results indicated that HES1 is not required for maintaining the adult pancreas under normal conditions, but is important for regeneration during recovery from pancreatitis; moreover, Hes1 plays different roles, depending on the tumor condition.

CONCLUSIONS

Our findings highlight the context-dependent roles of HES1 in the adult pancreas and pancreatic cancer.