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The development of therapies to prevent or treat salivary gland dysfunction has been limited by a lack of functional in vitro models. Specifically, critical markers of salivary gland secretory phenotype downregulate rapidly ex vivo. Here, we utilize a salivary gland tissue chip model to conduct a design of experiments (DoE) approach to test combinations of seven soluble cues that were previously shown to maintain or improve salivary gland cell function. This approach uses statistical techniques to improve efficiency and accuracy of combinations of factors. The DoE-designed culture conditions improve markers of salivary gland function. Data show that the EGFR inhibitor, EKI-785, maintains relative mRNA expression of Mist1, a key acinar cell transcription factor, while FGF10 and neurturin promote mRNA expression of Aqp5 and Tmem16a, channel proteins involved in secretion. Mist1 mRNA expression correlates with increased secretory function, including calcium signaling and mucin (PAS-AB) staining. Overall, this study demonstrates that media conditions can be efficiently optimized to support secretory function in vitro using a DoE approach. [ABSTRACT FROM AUTHOR]

Wei Wang,1 Xin Xie,2 Zhangjian Zhou,3 Hao Zhang2 1Department of Obstetrics and Gynecology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, 710061, People’s Republic of China; 2Department of Surgical Oncology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, 710061, People’s Republic of China; 3Department of Surgical Oncology, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, 710061, People’s Republic of ChinaCorrespondence: Hao ZhangDepartment of Surgical Oncology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, 710061, People’s Republic of ChinaTel +8613571946099Email hao.zhang@mail.xjtu.edu.cnBackground: Mist1 is a basic transcription factor, which plays an important role in the development of multiple organs, and may also regulate tumor progression by mediating epithelial-mesenchymal transformation. However, there is lack of research on its role of squamous cell carcinoma, especially in cervical squamous cell carcinoma.Methods: Bioinformatic methods were used to analyze gene expression, correlation, and patient survival according to the TCGA database. Thirty pairs of cancer tissues and distal cancer tissues from cervical cancer patients who received radical surgery were enrolled in the study. The expression of Mist1 was analyzed using Western blot. Furthermore, the potential associations among Mist1 expression, EMT biomarkers and various clinicopathological characteristics were investigated. All statistical tests employed in this study were two-sided, and P values < 0.05 were deemed statistically significant.Results: Overall survival data were obtained from TCGA-CESC dataset, containing 3 control samples and 305 tumor samples. The expression of Mist1 was significantly higher in primary tumor than in normal tissues (P< 0.001). The samples were divided into a low Mist1 expression group (n=144) and a high Mist1 expression group (n=146) according to the median expression level. Kaplan–Meier survival analysis revealed that high expression of Mist1 was significantly correlated with poor overall survival (P=0.032). We further explored the relationships between Mist1 and EMT. Among the 30 primary cervical cancer specimens investigated, the difference in Mist1 expressed statuses between cervical cancer tissues and distal noncancerous cervical tissues was significant (P=0.001). And the epithelial cell marker E-cadherin was downregulated in Mist1 overexpressed cervical cancer cells; however, the mesenchymal marker N-Cadherin and Twist was upregulated.Conclusion: Our study found that Mist1 seemed to play the role of oncogene in cervical squamous cell carcinoma and could be a potential biomarker.Keywords: Mist1, epithelial-mesenchymal transformation, cervical cancer

A single transcription factor, MIST1 (BHLHA15), maximizes secretory function in diverse secretory cells (like pancreatic acinar cells) by transcriptionally upregulating genes that elaborate secretory architecture. Here, we show that the scantly studied MIST1 target, ELAPOR1 (endosome/lysosome-associated apoptosis and autophagy regulator 1), is an evolutionarily conserved, novel mannose-6-phosphate receptor (M6PR) domain-containing protein. ELAPOR1 expression was specific to zymogenic cells (ZCs, the MIST1-expressing population in the stomach). ELAPOR1 expression was lost as tissue injury caused ZCs to undergo paligenosis (i.e., to become metaplastic and reenter the cell cycle). In cultured cells, ELAPOR1 trafficked with cis-Golgi resident proteins and with the trans-Golgi and late endosome protein: cation-independent M6PR. Secretory vesicle trafficking was disrupted by expression of ELAPOR1 truncation mutants. Mass spectrometric analysis of co-immunoprecipitated proteins showed ELAPOR1 and CI-M6PR shared many binding partners. However, CI-M6PR and ELAPOR1 must function differently, as CI-M6PR co-immunoprecipitated more lysosomal proteins and was not decreased during paligenosis in vivo. We generated Elapor1-/- mice to determine ELAPOR1 function in vivo. Consistent with in vitro findings, secretory granule maturation was defective in Elapor1-/- ZCs. Our results identify a role for ELAPOR1 in secretory granule maturation and help clarify how a single transcription factor maintains mature exocrine cell architecture in homeostasis and helps dismantle it during paligenosis. [ABSTRACT FROM AUTHOR]

SMARCB1(INI1)‐deficient sinonasal carcinoma is a recently recognized entity with wide histomorphologic spectrum. The classification of sinonasal adenocarcinoma (SNAC) is complex and yet to be redefined, especially the category of high‐grade non‐intestinal‐type SNAC. Recently SMARCB1(INI1)‐deficient SNACs with an unique oncocytoid/rhabdoid cytomorphology and variable degrees of glandular formation have been reported. Here we described a rare case of SMARCB1(INI1)‐deficient SNAC composed of mainly oncocytoid/rhabdoid cells with mixed solid and cribriform patterns. This case was originally diagnosed as non‐intestinal‐type SNAC and was reclassified due to complete loss expression of SMARCB1(INI1) by immunohistochemistry (IHC). The SMARCB1(INI1) stain provides a valuable tool for identification of this specific type of SNAC. We compared this case with other SNACs diagnosed in our department and reviewed relevant literature for this specific type of SNAC. [ABSTRACT FROM AUTHOR]

The development of therapies to prevent or treat salivary gland dysfunction has been limited by a lack of functional in vitro models. Specifically, critical markers of salivary gland secretory phenotype downregulate rapidly ex vivo. Here, we utilize a salivary gland tissue chip model to conduct a design of experiments (DoE) approach to test combinations of seven soluble cues that were previously shown to maintain or improve salivary gland cell function. This approach uses statistical techniques to improve efficiency and accuracy of combinations of factors. The DoE-designed culture conditions improve markers of salivary gland function. Data show that the EGFR inhibitor, EKI-785, maintains relative mRNA expression of Mist1, a key acinar cell transcription factor, while FGF10 and neurturin promote mRNA expression of Aqp5 and Tmem16a, channel proteins involved in secretion. Mist1 mRNA expression correlates with increased secretory function, including calcium signaling and mucin (PAS-AB) staining. Overall, this study demonstrates that media conditions can be efficiently optimized to support secretory function in vitro using a DoE approach.

Pancreatic acinar cells synthesize, package, and secrete digestive enzymes into the duodenum to aid in nutrient absorption and meet metabolic demands. When exposed to cellular stresses and insults, acinar cells undergo a dedifferentiation process termed acinar–ductal metaplasia (ADM). ADM lesions with oncogenic mutations eventually give rise to pancreatic ductal adenocarcinoma (PDAC). In healthy pancreata, the basic helix‐loop‐helix (bHLH) factors MIST1 and PTF1a coordinate an acinar‐specific transcription network that maintains the highly developed differentiation status of the cells, protecting the pancreas from undergoing a transformative process. However, when MIST1 and PTF1a gene expression is silenced, cells are more prone to progress to PDAC. In this study, we tested whether induced MIST1 or PTF1a expression in PDAC cells could (i) re‐establish the transcriptional program of differentiated acinar cells and (ii) simultaneously reduce tumor cell properties. As predicted, PTF1a induced gene expression of digestive enzymes and acinar‐specific transcription factors, while MIST1 induced gene expression of vesicle trafficking molecules as well as activation of unfolded protein response components, all of which are essential to handle the high protein production load that is characteristic of acinar cells. Importantly, induction of PTF1a in PDAC also influenced cancer‐associated properties, leading to a decrease in cell proliferation, cancer stem cell numbers, and repression of key ATP‐binding cassette efflux transporters resulting in heightened sensitivity to gemcitabine. Thus, activation of pancreatic bHLH transcription factors rescues the acinar gene program and decreases tumorigenic properties in pancreatic cancer cells, offering unique opportunities to develop novel therapeutic intervention strategies for this deadly disease.

Aims: Gastric neoplasms showing oxyntic gland differentiation (GAOGs) constitute a gastric neoplasm subtype that shows low atypia, thus similar to non‐neoplastic gastric oxyntic glands. Therefore, their diagnosis in biopsy specimens is difficult. GAOGs were first described in 2007, and introduced in the latest World Health Organization classification book as gastric adenocarcinoma of the fundic gland type (GA‐FG) and oxyntic gland adenoma. Previously, we assessed α1,4‐linked N‐acetylglucosamine (αGlcNAc) residues attached to the MUC6 scaffold in gastric neoplasms, and observed decreased αGlcNAc glycosylation in both differentiated‐type gastric cancer and high‐grade pyloric gland adenoma (PGA), a gastric cancer precursor. GA‐FG and PGA often harbour the same mutations. However, the αGlcNAc status in GAOGs remained unknown. To elucidate αGlcNAc expression in GAOGs, we performed the study. Methods and results: We assessed the expression of αGlcNAc; the mucin markers MUC6, MUC5AC, and MUC2; the gastric gland cell markers MIST1, pepsinogen 1 (PG1), H/K‐ATPase and chromogranin‐A (CGA); and the proliferation marker Ki67 in 13 GAOG lesions. All 13 (100%) were MUC6‐positive, whereas 10 (76.2%) were αGlcNAc‐negative. Moreover, all 13 (100%) were MIST1‐ and PG1‐positive, three (23.1%) were MUC5AC‐positive, four (30.8%) were H/K‐ATPase‐positive, and one (7.7%) was CGA‐positive. Conclusions: GAOGs frequently lost αGlcNAc residues on MUC6, but expressed the gastric gland progenitor marker MIST1 and aberrantly expressed various types of gastric gland cell lineage marker, suggestive of immature differentiation to gastric gland cells. Thus, diffuse MIST1 positivity and decreased αGlcNAc glycosylation on MUC6‐positive cells could serve as important biomarkers for the histopathological diagnosis of GAOG. [ABSTRACT FROM AUTHOR]

Salivary gland function is severely disrupted by radiation therapy used to treat patients diagnosed with head and neck cancer and by Sjögren's syndrome. The resulting condition, which results in xerostomia or dry mouth, is due to irreversible loss of the secretory acinar cells within the major salivary glands. There are presently no treatments for the resolution of xerostomia. Cell-based approaches could be employed to repopulate acinar cells in the salivary gland but investigations into potential therapeutic strategies are limited by the challenges of maintaining and expanding acinar cells in vitro. We investigate the encapsulation of salivary gland cell aggregates within PEG hydrogels as a means of culturing secretory acinar cells. Lineage tracing was used to monitor the fate of acinar cells isolated from murine submandibular gland (SMG). Upon initial formation in vitro, SMG aggregates comprise both acinar and duct cells, with the majority cells of acinar origin. With longer culture times, acinar cells significantly decreased the expression of specific markers and activated the expression of keratins normally found in duct cells. A similar acinar-to-duct cell transition was also observed in vivo, following duct ligation injury. These results indicate that under conditions of stress (mechanical and enzymatic isolation from glands) or injury (duct ligation), salivary gland acinar cells exhibit plasticity to adopt a duct cell phenotype. [ABSTRACT FROM AUTHOR]

Muscle, intestine, and stomach expression 1 (Mist1) is a transcription factor that functions in the development of granule organisation in serous exocrine cells of the gastrointestinal tract. The aim of this study was to investigate whether Mist1 can be used as a marker for acinic cell carcinoma (AciCC) of the salivary gland. Immunohistochemistry (IHC) was used to analyse Mist1 expression in AciCC (n = 26), secretory carcinoma (SC; n = 18) and 12 other types of salivary gland tumours (n = 99). Strong Mist1 staining was observed in normal serous acinar cells and plasma cells. Mist1 was diffusely expressed in AciCC, with the immunostaining intensity ranging from moderate (4/26) to strong (22/26). Most SC specimens were either negative (7/18) or focally and mildly positive (9/18) for Mist1. Only two SC cases demonstrated a moderate level of Mist1 staining. When moderate-to-strong Mist1 staining was used as the criterion of positivity, all the tested salivary gland tumours other than AciCC were negative for Mist1, except for two cases of SC. Previously cut tissue sections and decalcified specimens exhibited reduced Mist1 immunostaining intensity, which may give false-negative results. In summary, Mist1 is a sensitive marker for serous acinar cells of salivary glands and AciCC, and background non-tumour acinar cells and plasma cells can serve as good internal positive controls. [ABSTRACT FROM AUTHOR]

The role of transcription factors in cancer has attracted significant attention. Although genetic models indicate MIST1 functions as a tumor suppressor in mice, its role in human pancreatic cancer is unclear. We explored the expression and function of MIST1 in pancreatic cancer. Analysis of three GEO datasets (GSE16515, GSE15471, and GSE62165) showed MIST1 mRNA was significantly downregulated in human pancreatic cancer compared to normal pancreatic tissues. Moreover, MIST1 protein and mRNA expression were downregulated in pancreatic cancer cell lines compared to normal cells. Immunohistochemistry confirmed MIST1 was downregulated in human pancreatic cancer tissues (n = 47) and associated with differentiation. In vitro, overexpression of MIST1 reduced pancreatic cancer cell growth, migration, and invasion. In vivo, overexpression of MIST1 retarded tumor xenograft growth and decreased tumor cell dissemination to the liver. Furthermore, MIST1 reversed the epithelial-mesenchymal transition by downregulating Snail and upregulating E-cadherin. Knockdown of E-cadherin promoted the migration and invasion of cancer cells overexpressing MIST1. In conclusion, this study indicates restoring the expression of MIST1 reversed the EMT and reduced the tumorigenicity of pancreatic cancer cells partly via the Snail/E-cadherin pathway. [ABSTRACT FROM AUTHOR]

Pancreatic acinar cells synthesize, package, and secrete digestive enzymes into the duodenum to aid in nutrient absorption and meet metabolic demands. When exposed to cellular stresses and insults, acinar cells undergo a dedifferentiation process termed acinar–ductal metaplasia (ADM). ADM lesions with oncogenic mutations eventually give rise to pancreatic ductal adenocarcinoma (PDAC). In healthy pancreata, the basic helix‐loop‐helix (bHLH) factors MIST1 and PTF1a coordinate an acinar‐specific transcription network that maintains the highly developed differentiation status of the cells, protecting the pancreas from undergoing a transformative process. However, when MIST1 and PTF1a gene expression is silenced, cells are more prone to progress to PDAC. In this study, we tested whether induced MIST1 or PTF1a expression in PDAC cells could (i) re‐establish the transcriptional program of differentiated acinar cells and (ii) simultaneously reduce tumor cell properties. As predicted, PTF1a induced gene expression of digestive enzymes and acinar‐specific transcription factors, while MIST1 induced gene expression of vesicle trafficking molecules as well as activation of unfolded protein response components, all of which are essential to handle the high protein production load that is characteristic of acinar cells. Importantly, induction of PTF1a in PDAC also influenced cancer‐associated properties, leading to a decrease in cell proliferation, cancer stem cell numbers, and repression of key ATP‐binding cassette efflux transporters resulting in heightened sensitivity to gemcitabine. Thus, activation of pancreatic bHLH transcription factors rescues the acinar gene program and decreases tumorigenic properties in pancreatic cancer cells, offering unique opportunities to develop novel therapeutic intervention strategies for this deadly disease. [ABSTRACT FROM AUTHOR]

Sjögren’s syndrome (SjS) is an autoimmune disease that destroys the salivary glands and results in severe dry mouth. Mesenchymal stem cell (MSC) transplantation has been recently proposed as a promising therapy for restoring cells in multiple degenerative diseases. We have recently utilized advanced proteomics biochemical assays to identify the key molecules involved in the mesenchymal-epithelial transition (MET) of co-cultured mouse bone-marrow-derived MSCs mMSCs with primary salivary gland cells. Among the multiple transcription factors (TFs) that were differentially expressed, two major TFs were selected: muscle, intestine, and stomach expression-1 (MIST1) and transcription factor E2a (TCF3). These factors were assessed in the current study for their ability to drive the expression of acinar cell marker, alpha-salivary amylase 1 (AMY1), and ductal cell marker, cytokeratin19 (CK19), in vitro. Overexpression of MIST1-induced AMY1 expression while it had little effect on CK19 expression. In contrast, TCF3 induced neither of those cellular markers. Furthermore, we have identified that mMSCs express muscarinic-type 3 receptor (M3R) mainly in the cytoplasm and aquaporin 5 (AQP5) in the nucleus. While MIST1 did not alter M3R levels in mMSCs, a TCF3 overexpression downregulated M3R expressions in mMSCs. The mechanisms for such differential regulation of glandular markers by these TFs warrant further investigation.

The plasticity of gastric chief cells is exemplified by their ability to transdifferentiate into spasmolytic polypeptide-expressing metaplasia (SPEM) after parietal cell loss. We sought to determine if chief cell maturity is a limiting factor in the capacity to transdifferentiate. Mist1–/– mice, previously shown to form only immature chief cells, were treated with DMP-777 or L635 to study the capability of these immature chief cells to transdifferentiate into a proliferative metaplastic lineage after acute parietal cell loss. Mist1–/– mice treated with DMP-777 showed fewer chief cell to SPEM transitions. Mist1–/– mice treated with L635 demonstrated significantly fewer proliferative SPEM cells compared with control mice. Thus immature chief cells were unable to transdifferentiate efficiently into SPEM after acute parietal cell loss. To determine whether chief cell age affects transdifferentiation into SPEM, we used tamoxifen to induce YFP expression in chief cells of Mist1CreER/+; RosaYFP mice and subsequently treated the cells with L635 to induce SPEM at 1 to 3.5 mo after tamoxifen treatment. After L635 treatment to induce acute parietal cell loss, 43% of all YFP-positive cells at 1 mo posttamoxifen were SPEM cells, of which 44% of these YFP-positive SPEM cells were proliferative. By 2 mo after tamoxifen induction, only 24% of marked SPEM cells were proliferating. However, by 3.5 mo after tamoxifen induction, only 12% of marked chief cells transdifferentiated into SPEM and none were proliferative. Thus, as chief cells age, they lose their ability to transdifferentiate into SPEM and proliferate. Therefore, both functional maturation and age limit chief cell plasticity. [ABSTRACT FROM AUTHOR]

Several stem cell markers within the gastrointestinal epithelium have been identified in mice. One of the best characterized is Lgr5 (leucine-rich repeat-containing G-protein coupled receptor 5) and evidence suggests that Lgr5+ cells in the gut are the origin of gastrointestinal cancers. Reserve or facultative stem or progenitor cells with the ability to convert to Lgr5+ cells following injury have also been identified. Unlike the intestine, where Lgr5+ cells at the crypt base act as active stem cells, the stomach may contain unique stem cell populations, since gastric Lgr5+ cells seem to behave as a reserve rather than active stem cells, both in the corpus and in the antral glands. Gastrointestinal stem cells are supported by a specific microenvironment, the stem cell niche, which also promotes tumorigenesis. This review focuses on stem cell markers in the gut and their supporting niche factors. It also discusses the molecular mechanisms that regulate stem cell function and tumorigenesis.

Fibroblast growth factor 21 (FGF21) is a key regulator of metabolism under conditions of stress such as starvation, obesity, and hypothermia. Rapid induction of FGF21 is also observed in experimental models of pancreatitis, and FGF21 reduces tissue damage observed in these models, suggesting a nonmetabolic function. Pancreatitis is a debilitating disease with significant morbidity that greatly increases the risk of pancreatic ductal adenocarcinoma. The goals of this study were to examine the regulation and function of FGF21 in acinar cell injury, specifically in a mouse model of pancreatic injury (Mist1-/-). Mist1-/- mice exhibit acinar cell disorganization, decreased acinar cell communication and exocytosis, and increased sensitivity to cerulein- induced pancreatitis (CIP). Examination of Fgf21 expression in Mist1-/- mice by qRT-PCR, Northern blot, and Western blot analyses showed a marked decrease in pancreatic Fgf21 expression before and after induction of CIP compared with C57Bl/6 mice. To determine whether the loss of FGF21 accounted for the Mist1-/- phenotypes, we generated Mist1-/- mice overexpressing human FGF21 from the ApoE promoter (Mist1-/-ApoE-FGF21). Reexpression of FGF21 partially mitigated pancreatic damage in Mist1-/- tissue based on reduced intrapancreatic enzyme activation, reduced expression of genes involved in fibrosis, and restored cell-cell junctions. Interestingly, alteration of Fgf21 expression in Mist1-/- tissue was not simply due to a loss of direct transcriptional regulation by MIST1. Chromatin immunopreciptation indicated that the loss of Fgf21 in the Mist1-/- pancreas is due, in part, to epigenetic silencing. Thus, our studies identify a new role for FGF21 in reducing acinar cell injury and uncover a novel mechanism for regulating Fgf21 gene expression. [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma (PDAC) has a 5 year survival rate post-diagnosis of < 5%. Individuals with chronic pancreatitis (CP) are 20-fold more likely to develop PDAC, making it a significant risk factor for PDAC. While the relationship for the increased susceptibility to PDAC is unknown, loss of the acinar cell phenotype is common to both pathologies. Pancreatic acinar cells can dedifferentiate or trans-differentiate into a number of cell types including duct cells, β cells, hepatocytes and adipocytes. Knowledge of the molecular pathways that regulate this plasticity should provide insight into PDAC and CP. MIST1 (encoded by Bhlha15 in mice) is a transcription factor required for complete acinar cell maturation. The goal of this study was to examine the plasticity of acinar cells that do not express MIST1 ( Mist1−/−). The fate of acinar cells from C57Bl6 or congenic Mist1−/− mice expressing an acinar specific, tamoxifen-inducible Cre recombinase mated to Rosa26 reporter LacZ mice ( Mist1 CreERT/− R26r) was determined following culture in a three-dimensional collagen matrix. Mist1 CreERT/− R26r acini showed increased acinar dedifferentiation, formation of ductal cysts and transient increases in PDX1 expression compared to wild-type acinar cells. Other progenitor cell markers, including Foxa1, Sox9, Sca1 and Hes1, were elevated only in Mist1−/− cultures. Analysis of protein kinase C (PKC) isoforms by western blot and immunofluorescence identified increased PKCε accumulation and nuclear localization of PKCδ that correlated with increased duct formation. Treatment with rottlerin, a PKCδ-specific inhibitor, but not the PKCε-specific antagonist εV1-2, reduced acinar dedifferentiation, progenitor gene expression and ductal cyst formation. Immunocytochemistry on CP or PDAC tissue samples showed reduced MIST1 expression combined with increased nuclear PKCδ accumulation. These results suggest that the loss of MIST1 is a common event during PDAC and CP and events that affect MIST1 function and expression may increase susceptibility to these pathologies. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The basic helix–loop–helix (bHLH) protein Mist1 is an important exocrine pancreas transcriptional factor expressed in the acinar cells of mammals. In the present study, we cloned the homologous Mist1 cDNA encoding a predicted protein of 184 amino acids in zebrafish. The typical bHLH domain of zebrafish Mist1 shares high identity with that of its orthologs in mouse, rat, and human. Expression analysis revealed that Mist1 maternal transcripts are distinct in the very beginning of embryogenesis and that endogenous Mist1 is chronologically expressed in polster, hatching gland, hindbrain and appears exclusively in the pancreas from 72hpf onward. Knockdown of Mist1 conditionally causes mild morphological defects in embryos. In MO-treated embryos, midbrain–hindbrain boundary is missing and exocrine pancreas is significantly reduced and disorganized. These results suggest that Mist1 functions in an evolutionary conserved way as a key transcriptional regulator specific for exocrine pancreas development in zebrafish. [Copyright &y& Elsevier]

During differentiation, neuroendocrine cells acquire highly amplified capacities to synthesize neuropeptides to overcome dilution of these signals in the general circulation. Once mature, the normal functioning of integrated physiological systems requires that neuroendocrine cells remain plastic to dramatically alter neuropeptide expression for long periods in response to hormonal and electrical cues. The mechanisms underlying the long-term regulation of neuroendocrine systems are poorly understood. Here we show that the Drosophila basic helix-loop-helix protein DIMM, a critical regulator of neuroendocrine cell differentiation, controls secretory capacity in mature neurons. DIMM expression began embryonically but persisted in adults. Through spatial and temporal manipulation of transgene expression in vivo, we defined two phases of prosecretory DIMM activity. During an embryonic critical window, DIMM controlled the differentiation of amplified expression of the neuropeptide leucokinin. At the onset of metamorphosis, levels of DIMM decreased in the insulin-producing cells (IPCs) in parallel with a marked reduction in levels of Drosophila insulin-like peptide 2 and a key neuropeptide biosynthetic enzyme peptidylglycine α-monooxygenase (PHM). Overexpression of DIMM in the IPCs prevented the decrease in PHM levels at this stage. In addition, transient overexpression of DIMM in adults produced a dramatic increase in PHM levels in numerous neurons located throughout the brain. These findings provide insights into the mechanisms controlling the maintenance of differentiated cell states, and they suggest an effective means for dynamically adjusting the strength of hormonal signals in diverse homeostatic systems. [ABSTRACT FROM AUTHOR]

Cellular proliferation, specification and differentiation in developing tissues are tightly coordinated by groups of transcription factors in response to extrinsic and intrinsic signals. Furthermore, renewable pools of stem cells in adult tissues are subject to similar regulation. Basic helix–loop–helix (bHLH) proteins are a group of transcription factors that exert such a determinative influence on a variety of developmental pathways from C. elegans to humans, and we wished to exclusively identify novel members from within the whole human bHLH family. We have, therefore, developed an ‘empirical custom fingerprint’, to define the class II bHLH domain and exclusively identify these proteins in silico. We have identified nine previously uncharacterised human class II proteins, four of which were novel, by interrogating conceptual translations of the GenBank HTGS database. RT-PCR and mammalian 2-hybrid analysis of a subset of the factors demonstrated that they were indeed expressed, and were able to interact with an appropriate binding partner in vitro. Thus, we are now approaching an almost complete listing of human class II bHLH factors. [Copyright &y& Elsevier]

Ulcerative colitis (UC) is a chronic inflammatory intestinal disease. Genetic susceptibility, gut microbiota and mucosal immune dysfunction play important roles in the pathogenesis and development of UC. We investigate the effect of Mist1 in model of colitis and its underlying mechanism. The expressions of Mist1 in patients with colitis tissue were up-regulated. Meanwhile, Mist1 mRNA and protein expressions in DSS-induced colitis mice model were also induced and Mist1 mRNA and protein expressions of LPS induced THP-1 cell were also up-regulated. we found Mist1 human protein promoted inflammation in DSS-induced colitis mice by NLRP3. So, we up-regulated Mist1 expression and over-expression of Mist1 promoted IL-1β and NLRP3 protein expression levels in vitro model. However, down-regulation of Mist1 suppressed IL-1β and NLRP3 protein expression levels in vitro model. Next, SNAI1 is a shooting point of Mist1 in the effects of Mist1 in colitis. The inhibition of SNAI1 reduced the effects of Mist1 on NLRP3 inflammasome in vitro model. Activation of SNAI1 induced the effects of Mist1 on NLRP3 inflammasome in vitro model. Lastly, anti-SNAI1 human protein lowered the effects of Mist1 human protein on NLRP3 inflammasome in DSS-induced colitis mice. We demonstrated that Mist1 promoted inflammation in colitis model via NLRP3 inflammasome by SNAI1, whereas the absence of these macrophages led to a significant improvement in colitis treatment. [ABSTRACT FROM AUTHOR]

As a secretory cell transcription factor, muscle intestine stomach expression 1 (Mist1) is associated with serous secretory cell development and gastric chief cell maturation. Here, we focus on the function of Mist1 in gastric adenocarcinoma carcinogenesis. Based on clinical data and a mouse model of gastric cancer, we found that Mist1 expression was reduced in gastric cancer. Then, we overexpressed Mist1 using a lentivirus system and found that overexpression of Mist1 could inhibit gastric cancer cell proliferation, migration and invasion in vitro. Additionally, in vivo , we assessed the function of Mist1 in a gastric cancer xenograft model and distant pulmonary metastasis model. Overexpression of Mist1 decreased tumour growth and distant metastasis in vivo , suggesting that Mist1 acts as a tumour suppressor in gastric carcinogenesis. Furthermore, Mist1 overexpression inhibited epithelial-mesenchymal transition (EMT) in gastric cancer by suppressing β-catenin transcription activity and then the Wingless and INT-1 (Wnt)/β-catenin signalling pathway, which could be reversed by a Wnt/β-catenin-specific agonist. In conclusion, this study indicated that overexpression of Mist1 could reverse EMT in gastric carcinogenesis by inhibiting the Wnt/β-catenin signalling pathway and that Mist1 might be a novel marker for early gastric cancer screening., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Sjögren's syndrome (SjS) is an autoimmune disease that destroys the salivary glands and results in severe dry mouth. Mesenchymal stem cell (MSC) transplantation has been recently proposed as a promising therapy for restoring cells in multiple degenerative diseases. We have recently utilized advanced proteomics biochemical assays to identify the key molecules involved in the mesenchymal-epithelial transition (MET) of co-cultured mouse bone-marrow-derived MSCs mMSCs with primary salivary gland cells. Among the multiple transcription factors (TFs) that were differentially expressed, two major TFs were selected: muscle, intestine, and stomach expression-1 (MIST1) and transcription factor E2a (TCF3). These factors were assessed in the current study for their ability to drive the expression of acinar cell marker, alpha-salivary amylase 1 (AMY1), and ductal cell marker, cytokeratin19 (CK19), in vitro. Overexpression of MIST1-induced AMY1 expression while it had little effect on CK19 expression. In contrast, TCF3 induced neither of those cellular markers. Furthermore, we have identified that mMSCs express muscarinic-type 3 receptor (M3R) mainly in the cytoplasm and aquaporin 5 (AQP5) in the nucleus. While MIST1 did not alter M3R levels in mMSCs, a TCF3 overexpression downregulated M3R expressions in mMSCs. The mechanisms for such differential regulation of glandular markers by these TFs warrant further investigation. [ABSTRACT FROM AUTHOR]

Several stem cell markers within the gastrointestinal epithelium have been identified in mice. One of the best characterized is Lgr5 (leucine-rich repeat-containing G-protein coupled receptor 5) and evidence suggests that Lgr5+ cells in the gut are the origin of gastrointestinal cancers. Reserve or facultative stem or progenitor cells with the ability to convert to Lgr5+ cells following injury have also been identified. Unlike the intestine, where Lgr5+ cells at the crypt base act as active stem cells, the stomach may contain unique stem cell populations, since gastric Lgr5+ cells seem to behave as a reserve rather than active stem cells, both in the corpus and in the antral glands. Gastrointestinal stem cells are supported by a specific microenvironment, the stem cell niche, which also promotes tumorigenesis. This review focuses on stem cell markers in the gut and their supporting niche factors. It also discusses the molecular mechanisms that regulate stem cell function and tumorigenesis. [ABSTRACT FROM AUTHOR]

Muscle, intestine, and stomach expression 1 (Mist1) is a transcription factor that functions in the development of granule organisation in serous exocrine cells of the gastrointestinal tract. The aim of this study was to investigate whether Mist1 can be used as a marker for acinic cell carcinoma (AciCC) of the salivary gland. Immunohistochemistry (IHC) was used to analyse Mist1 expression in AciCC (n = 26), secretory carcinoma (SC; n = 18) and 12 other types of salivary gland tumours (n = 99). Strong Mist1 staining was observed in normal serous acinar cells and plasma cells. Mist1 was diffusely expressed in AciCC, with the immunostaining intensity ranging from moderate (4/26) to strong (22/26). Most SC specimens were either negative (7/18) or focally and mildly positive (9/18) for Mist1. Only two SC cases demonstrated a moderate level of Mist1 staining. When moderate-to-strong Mist1 staining was used as the criterion of positivity, all the tested salivary gland tumours other than AciCC were negative for Mist1, except for two cases of SC. Previously cut tissue sections and decalcified specimens exhibited reduced Mist1 immunostaining intensity, which may give false-negative results. In summary, Mist1 is a sensitive marker for serous acinar cells of salivary glands and AciCC, and background non-tumour acinar cells and plasma cells can serve as good internal positive controls.

Background: Paneth cells are professional secretory cells found within the small intestinal crypt epithelium. Although their role as part of the innate immune complex providing antimicrobial secretory products is well-known, the mechanisms that control secretory capacity are not well-understood. MIST1 is a scaling factor that is thought to control secretory capacity of exocrine cells., Methods: Mist1 +/+ and Mist1 -/- mice were used to evaluate the function of MIST1 in small intestinal Paneth cells. We used histologic and immunofluorescence staining to evaluate small intestinal tissue for proliferation and lineage allocation. Total RNA was isolated to evaluate gene expression. Enteroid culture was used to evaluate the impact of the absence of MIST1 expression on intestinal stem cell function., Results: Absence of MIST1 resulted in increased numbers of Paneth cells exhibiting an intermediate cell phenotype but otherwise did not alter overall epithelial cell lineage allocation. Muc2 and lysozyme staining confirmed the presence of intermediate cells at the crypt base of Mist1 -/- mice. These changes were not associated with changes in mRNA expression of transcription factors associated with lineage allocation, and they were not abrogated by inhibition of Notch signaling. However, the absence of MIST1 expression was associated with alterations in Paneth cell morphology including decreased granule size and distended rough endoplasmic reticulum. Absence of MIST1 was associated with increased budding of enteroid cultures; however, there was no evidence of increased intestinal stem cell numbers in vivo., Conclusions: MIST1 plays an important role in organization of the Paneth cell secretory apparatus and managing endoplasmic reticulum stress. This role occurs downstream of Paneth cell lineage allocation., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in North America, accounting for >30,000 deaths annually. Although somatic activating mutations in KRAS appear in 97% of PDAC patients, additional factors are required to initiate PDAC. Because mutations in genes encoding chromatin remodelling proteins have been implicated in KRAS-mediated PDAC, we investigated whether loss of chromatin remodeler ɑ-thalassemia, mental-retardation, X-linked (ATRX) affects oncogenic KRAS's ability to promote PDAC. ATRX affects DNA replication, repair, and gene expression and is implicated in other cancers including glioblastomas and pancreatic neuroendocrine tumors. The hypothesis was that deletion of Atrx in pancreatic acinar cells will increase susceptibility to injury and oncogenic KRAS., Methods: Mice allowing conditional loss of Atrx within pancreatic acinar cells were examined after induction of recurrent cerulein-induced pancreatitis or oncogenic KRAS ( KRAS G12D ). Histologic, biochemical, and molecular analysis examined pancreatic pathologies up to 2 months after induction of Atrx deletion., Results: Mice lacking Atrx showed more progressive damage, inflammation, and acinar-to-duct cell metaplasia in response to injury relative to wild-type mice. In combination with KRAS G12D , Atrx -deficient acinar cells showed increased fibrosis, inflammation, progression to acinar-to-duct cell metaplasia, and pre-cancerous lesions relative to mice expressing only KRAS G12D . This sensitivity appears only in female mice, mimicking a significant prevalence of ATRX mutations in human female PDAC patients., Conclusions: Our results indicate the absence of ATRX increases sensitivity to injury and oncogenic KRAS only in female mice. This is an instance of a sex-specific mutation that enhances oncogenic KRAS's ability to promote pancreatic intraepithelial lesion formation.

Mist1 was recently shown to identify a discrete population of stem cells within the isthmus of the oxyntic gland within the gastric corpus. Chief cells at the base of the gastric corpus also express Mist1 . The relevance of Mist1 expression as a marker of specific cell populations within the antral glands of the distal stomach, however, is unknown. Using Mist1 -CreERT mice, we revealed that Mist1 + antral cells, distinct from the Mist1 + population in the corpus, comprise long-lived progenitors that reside within the antral isthmus above Lgr5 + or CCK2R + cells. Mist1 + antral progenitors can serve as an origin of antral tumors induced by loss of Apc or MNU treatment. Mist1 + antral progenitors, as well as other antral stem/progenitor population, express Cxcr4, and are located in close proximity to Cxcl12 (the Cxcr4 ligand)-expressing endothelium. During antral carcinogenesis, there is an expansion of Cxcr4 + epithelial cells as well as the Cxcl12 + perivascular niche. Deletion of Cxcl12 in endothelial cells or pharmacological blockade of Cxcr4 inhibits antral tumor growth. Cxcl12/Cxcr4 signaling may be a potential therapeutic target., Competing Interests: CONFLICTS OF INTEREST The authors disclose no conflicts.

The cellular origin of digestive cancers has been a long-standing question in the cancer field. Mouse models have identified long-lived stem cells in most organ systems, including the luminal gastrointestinal tract, and numerous studies have pointed to tissue resident stem cells as the main cellular origin of cancer. During gastric carcinogenesis, chronic inflammation induces genetic and epigenetic alterations in long-lived stem cells, along with expansion of stem cell niches, eventually leading to invasive cancer. The gastric corpus and antrum have distinct stem cells and stem cell niches, suggesting differential regulation of cancer initiation at the 2 sites. In this short review, we discuss recent experimental models and human studies, which provide important insights into the pathogenesis of gastric cancer.

Acinar cells of the pancreas produce the majority of enzymes required for digestion and make up >90% of the cells within the pancreas. Due to a common developmental origin and the plastic nature of the acinar cell phenotype, these cells have been identified as a possible source of β cells as a therapeutic option for Type I diabetes. However, recent evidence indicates that acinar cells are the main source of pancreatic intraepithelial neoplasias (PanINs), the predecessor of pancreatic ductal adenocarcinoma (PDAC). The conversion of acinar cells to either β cells or precursors to PDAC is dependent on reprogramming of the cells to a more primitive, progenitor-like phenotype, which involves changes in transcription factor expression and activity, and changes in their epigenetic program. This review will focus on the mechanisms that promote acinar cell reprogramming, as well as the factors that may affect these mechanisms.

As they mature, professional secretory cells like pancreatic acinar and gastric chief cells induce the transcription factor MIST1 (also known as BHLHA15) to substantially scale up production of large secretory granules in a process that involves expansion of apical cytoplasm and redistribution of lysosomes and mitochondria. How a scaling factor like MIST1 rearranges cellular architecture simply by regulating expression levels of its transcriptional targets is unknown. RAB26 is a MIST1 target whose role in MIST1-mediated secretory cell maturation is also unknown. Here, we confirm that RAB26 expression, unlike most Rabs which are ubiquitously expressed, is tissue specific and largely confined to MIST1-expressing secretory tissues. Surprisingly, functional studies showed that RAB26 predominantly associated with LAMP1/cathepsin D lysosomes and not directly with secretory granules. Moreover, increasing RAB26 expression - by inducing differentiation of zymogen-secreting cells or by direct transfection - caused lysosomes to coalesce in a central, perinuclear region. Lysosome clustering in turn caused redistribution of mitochondria into distinct subcellular neighborhoods. The data elucidate a novel function for RAB26 and suggest a mechanism for how cells could increase transcription of key effectors to reorganize subcellular compartments during differentiation.