Haploinsufficiency of phosphodiesterase 10A activates PI3K/AKT signaling independent of PTEN to induce an aggressive glioma phenotype.

Glioblastoma is universally fatal and characterized by frequent chromosomal copy number alterations harboring oncogenes and tumor suppressors. In this study, we analyzed exome-wide human glioblastoma copy number data and found that cytoband 6q27 is an independent poor prognostic marker in multiple data sets. We then combined CRISPR-Cas9 data, human spatial transcriptomic data, and human and mouse RNA sequencing data to nominate PDE10A as a potential haploinsufficient tumor suppressor in the 6q27 region. Mouse glioblastoma modeling using the RCAS/tv-a system confirmed that Pde10a suppression induced an aggressive glioma phenotype in vivo and resistance to temozolomide and radiation therapy in vitro. Cell culture analysis showed that decreased Pde10a expression led to increased PI3K/AKT signaling in a Pten-independent manner, a response blocked by selective PI3K inhibitors. Single-nucleus RNA sequencing from our mouse gliomas in vivo, in combination with cell culture validation, further showed that Pde10a suppression was associated with a proneural-to-mesenchymal transition that exhibited increased cell adhesion and decreased cell migration. Our results indicate that glioblastoma patients harboring PDE10A loss have worse outcomes and potentially increased sensitivity to PI3K inhibition.

Mesenchymal Osr1+ cells regulate embryonic lymphatic vessel formation.

The lymphatic system is formed during embryonic development by the commitment of specialized lymphatic endothelial cells (LECs) and their subsequent assembly in primary lymphatic vessels. Although lymphatic cells are in continuous contact with mesenchymal cells during development and in adult tissues, the role of mesenchymal cells in lymphatic vasculature development remains poorly characterized. Here, we show that a subpopulation of mesenchymal cells expressing the transcription factor Osr1 are in close association with migrating LECs and established lymphatic vessels in mice. Lineage tracing experiments revealed that Osr1+ cells precede LEC arrival during lymphatic vasculature assembly in the back of the embryo. Using Osr1-deficient embryos and functional in vitro assays, we show that Osr1 acts in a non-cell-autonomous manner controlling proliferation and early migration of LECs to peripheral tissues. Thereby, mesenchymal Osr1+ cells control, in a bimodal manner, the production of extracellular matrix scaffold components and signal ligands crucial for lymphatic vessel formation.

Cellular and molecular characteristics of stromal Lkb1 deficiency-induced gastrointestinal polyposis based on single-cell RNA sequencing.

Liver kinase B1 (Lkb1), encoded by serine/threonine kinase (Stk11), is a serine/threonine kinase and tumor suppressor that is strongly implicated in Peutz-Jeghers syndrome (PJS). Numerous studies have shown that mesenchymal-specific Lkb1 is sufficient for the development of PJS-like polyps in mice. However, the cellular origin and components of these Lkb1-associated polyps and underlying mechanisms remain elusive. In this study, we generated tamoxifen-inducible Lkb1flox/flox;Myh11-Cre/ERT2 and Lkb1flox/flox;PDGFRα-Cre/ERT2 mice, performed single-cell RNA sequencing (scRNA-seq) and imaging-based lineage tracing, and aimed to investigate the cellular complexity of gastrointestinal polyps associated with PJS. We found that Lkb1flox/+;Myh11-Cre/ERT2 mice developed gastrointestinal polyps starting at 9 months after tamoxifen treatment. scRNA-seq revealed aberrant stem cell-like characteristics of epithelial cells from polyp tissues of Lkb1flox/+;Myh11-Cre/ERT2 mice. The Lkb1-associated polyps were further characterized by a branching smooth muscle core, abundant extracellular matrix deposition, and high immune cell infiltration. In addition, the Spp1-Cd44 or Spp1-Itga8/Itgb1 axes were identified as important interactions among epithelial, mesenchymal, and immune compartments in Lkb1-associated polyps. These characteristics of gastrointestinal polyps were also demonstrated in another mouse model, tamoxifen-inducible Lkb1flox/flox;PDGFRα-Cre/ERT2 mice, which developed obvious gastrointestinal polyps as early as 2-3 months after tamoxifen treatment. Our findings further confirm the critical role of mesenchymal Lkb1/Stk11 in gastrointestinal polyposis and provide novel insight into the cellular complexity of Lkb1-associated polyp biology. © 2024 The Pathological Society of Great Britain and Ireland.

Emerging biological functions of Twist1 in cell differentiation.

Twist1 is required for embryonic development and expresses after birth in mesenchymal stem cells derived from mesoderm, where it governs mesenchymal cell development. As a well-known regulator of epithelial-mesenchymal transition or embryonic organogenesis, Twist1 is important in a variety of developmental systems, including mesoderm formation, neurogenesis, myogenesis, cranial neural crest cell migration, and differentiation. In this review, we first highlight the physiological significance of Twist1 in cell differentiation, including osteogenic, chondrogenic, and myogenic differentiation, and then detail its probable molecular processes and signaling pathways. On this premise, we summarize the significance of Twist1 in distinct developmental disorders and diseases to provide a reference for studies on cell differentiation/development-related diseases.

Mesenchymal cells regulate enteric neural crest cell migration via RET-GFRA1b trans-signaling.

During early development, the enteric nervous system forms from the migration of enteric neural crest cells (ENCCs) from the foregut to the hindgut, where they undergo proliferation and differentiation facilitated by interactions with enteric mesenchymal cells (EMCs). This study investigates the impact on ENCC migration of EMC-ENCC communication mediated by GFRA1b expressed in EMCs. GFRA1-expressing cells in day 11-12 (E11-12) mouse embryos differentiated into smooth muscle cells from E12 onwards. Observations at E12-13.5 revealed high levels of GFRA1 expression on the anti-mesenteric side of the hindgut, correlating with enhanced ENCC migration. This indicates that GFRA1 in EMCs plays a role in ENCC migration during development. Examining GFRA1 isoforms, we found high levels of GFRA1b, which lacks amino acids 140-144, in EMCs. To assess the impact of GFRA1 isoforms on EMC-ENCC communication, we conducted neurosphere drop assays. This revealed that GFRA1b-expressing cells promoted GDNF-dependent extension and increased neurite density in ENCC neurospheres. Co-culture of ENCC mimetic cells expressing RET and GFRA1a with EMC mimetic cells expressing GFRA1a, GFRA1b, or vector alone showed that only GFRA1b-expressing co-cultured cells sustained RET phosphorylation in ENCC-mimetic cells for over 120 min upon GDNF stimulation. Our study provides evidence that GFRA1b-mediated cell-to-cell communication plays a critical role in ENCC motility in enteric nervous system development. These findings contribute to understanding the cellular interactions and signaling mechanisms that underlie enteric nervous system formation and highlight potential therapeutic targets for gastrointestinal motility disorders.

2,3,7,8-Tetrachlorodibenzo-p-Dioxin Suppresses Mesenchymal Cell Proliferation and Migration Through miR-214-3p in Cleft Palate.

OBJECTIVE: The aetiology of CL/P is complicated, with both genetic and environmental factors. This study aimed to investigate the association between TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) exposure and changes in the expression of miR-214-3p in the context of cleft palate. DESIGN: In this study, we established a fetal mouse cleft palate model using TCDD and differentially expressed miRNAs were analysed by microarray analysis and verified by qRT-PCR. Finally, we demonstrated the effects of TCDD and microRNAs on the proliferation and migration of mesenchymal cells by using CCK8, EDU, Transwell, and wound-healing assays. RESULTS: Our findings revealed significant upregulation of miRNAs such as miR-214-3p, miR-296-5p, and miR-33-5p in the TCDD intervention group, while miRNAs like miR-92a-3p, miR-126a-3p, and miR-411-5p were significantly downregulated. Notably, qRT-PCR testing confirmed a significant difference in miR-214-3P expression. Further investigations involved the overexpression of miR-214-3p, reducing cell proliferation and migration in primary mouse embryonic palatal mesenchymal (MEPM) cells. CONCLUSIONS: These results are consistent with the finding that TCDD suppresses palatal mesenchymal cell proliferation and migration through miR-214-3p. In conclusion, miR-214-3p probably plays a role in TCDD-induced cleft palates in mice.

Distribution changes of non-self-test cells and self-tunic cells surrounding the outer body during Ciona metamorphosis.

BACKGROUND: Ascidians significantly change their body structure through metamorphosis, but the spatio-temporal cell dynamics in the early metamorphosis stage has not been clarified. A natural Ciona embryo is surrounded by maternally derived non-self-test cells before metamorphosis. However, after metamorphosis, the juvenile is surrounded by self-tunic cells derived from mesenchymal cell lineages. Both test cells and tunic cells are thought to be changed their distributions during metamorphosis, but the precise timing is unknown. RESULTS: Using a metamorphosis induction by mechanical stimulation, we investigated the dynamics of mesenchymal cells during metamorphosis in a precise time course. After the stimulation, two-round Ca2+ transients were observed. Migrating mesenchymal cells came out through the epidermis within 10 min after the second phase. We named this event "cell extravasation." The cell extravasation occurred at the same time as the backward movement of posterior trunk epidermal cells. Timelapse imaging of transgenic-line larva revealed that non-self-test cells and self-tunic cells temporarily coexist outside the body until the test cells are eliminated. At the juvenile stage, only extravasated self-tunic cells remained outside the body. CONCLUSIONS: We found that mesenchymal cells extravasated following two-round Ca2+ transients, and distributions of test cells and tunic cells changed in the outer body after tail regression.

High throughput miRNA sequencing and bioinformatics analysis identify the mesenchymal cell proliferation and apoptosis related miRNAs during fetal mice palate development.

BACKGROUND: Palatogenesis requires a precise spatiotemporal regulation of gene expression. Recent studies indicate that microRNAs (miRNAs) are key factors in normal palatogenesis. The present study aimed to explain the regulatory mechanisms of miRNAs during palate development. METHODS: Pregnant ICR mice were choose at embryonic day 10.5 (E10.5). Hemotoxylin and eosin (H&E) staining was used to observe the morphological changes during the development of palatal process at embryonic day (E)13.5, E14.0, E14.5, E15.0 and E15.5. The fetal palatal tissues were collected at E13.5, E14.0, E14.5 and E15.0 to explore miRNA expression and function by high throughput sequencing and bioinformatic analysis. Mfuzz cluster analysis was used to look for miRNAs related to the fetal mice palate formation. The target genes of miRNAs were predicted by miRWalk. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed base on target genes. The mesenchymal cell proliferation and apoptosis related miRNAs-genes networks were predicted and constructed using miRWalk and Cytoscape software. The expression of mesenchymal cell proliferation and apoptosis related miRNAs at the E13.5, E14.0, E14.5, and E15.0 was detected by a quantitative real-time PCR (RT-qPCR) assay. RESULTS: H&E staining found that the palatal process grows vertically along the sides of the tongue at E13.5, the position of the tongue begins to descend and the bilateral palatal processes rise above the tongue at E14.0, the palatal process grows horizontally at E14.5, there is palatal contact fusion at E15.0, and the palatal suture disappeared at E15.5. Nine clusters of miRNA expression changes were identified in the fetal mice palate formation progression, including two reducing trends, two rising trends and five disordered trends. Next, the heatmap showed the miRNA expression from Clusters 4, 6, 9, 12 in the E13.5, E14.0, E14.5 and E15.0 groups. GO functional and KEGG pathway enrichment analysis found target genes of miRNAs in clusters involved in regulation of mesenchymal phenotype and the mitogen-activated protein kinase (MAPK) signaling pathway. Next, mesenchymal phenotype related miRNA-genes networks were constructed. The heatmap showing that the mesenchymal phenotype related miRNA expression of Clusters 4, 6, 9 and 12 at E13.5, E14.0, E14.5 and E15.0. Furthermore, the mesenchymal cell proliferation and apoptosis related miRNA-gene networks were identified in Clusters 6 and 12, including mmu-miR-504-3p-Hnf1b, etc. The expression level of mesenchymal cell proliferation and apoptosis related miRNAs at the E13.5, E14.0, E14.5, and E15.0 was verified by a RT-qPCR assay. CONCLUSIONS: For the first time, we identified that clear dynamic miRNA expression during palate development. Furthermore, we demonstrated that mesenchymal cell proliferation and apoptosis related miRNAs, genes and the MAPK signaling pathway are important during fetal mice palate development.

Erk and MAPK signaling is essential for intestinal development through Wnt pathway modulation.

Homeostasis of intestinal stem cells (ISCs) is maintained by the orchestration of niche factors and intrinsic signaling networks. Here, we have found that deletion of Erk1 and Erk2 (Erk1/2) in intestinal epithelial cells at embryonic stages resulted in an unexpected increase in cell proliferation and migration, expansion of ISCs, and formation of polyp-like structures, leading to postnatal death. Deficiency of epithelial Erk1/2 results in defects in secretory cell differentiation as well as impaired mesenchymal cell proliferation and maturation. Deletion of Erk1/2 strongly activated Wnt signaling through both cell-autonomous and non-autonomous mechanisms. In epithelial cells, Erk1/2 depletion resulted in loss of feedback regulation, leading to Ras/Raf cascade activation that transactivated Akt activity to stimulate the mTor and Wnt/ß-catenin pathways. Moreover, Erk1/2 deficiency reduced the levels of Indian hedgehog and the expression of downstream pathway components, including mesenchymal Bmp4 - a Wnt suppressor in intestines. Inhibition of mTor signaling by rapamycin partially rescued Erk1/2 depletion-induced intestinal defects and significantly prolonged the lifespan of mutant mice. These data demonstrate that Erk/Mapk signaling functions as a key modulator of Wnt signaling through coordination of epithelial-mesenchymal interactions during intestinal development.

Multilineage contribution of CD34+ cells in cardiac remodeling after ischemia/reperfusion injury.

The ambiguous results of multiple CD34+ cell-based therapeutic trials for patients with heart disease have halted the large-scale application of stem/progenitor cell treatment. This study aimed to delineate the biological functions of heterogenous CD34+ cell populations and investigate the net effect of CD34+ cell intervention on cardiac remodeling. We confirmed, by combining single-cell RNA sequencing on human and mouse ischemic hearts and an inducible Cd34 lineage-tracing mouse model, that Cd34+ cells mainly contributed to the commitment of mesenchymal cells, endothelial cells (ECs), and monocytes/macrophages during heart remodeling with distinct pathological functions. The Cd34+-lineage-activated mesenchymal cells were responsible for cardiac fibrosis, while CD34+Sca-1high was an active precursor and intercellular player that facilitated Cd34+-lineage angiogenic EC-induced postinjury vessel development. We found through bone marrow transplantation that bone marrow-derived CD34+ cells only accounted for inflammatory response. We confirmed using a Cd34-CreERT2; R26-DTA mouse model that the depletion of Cd34+ cells could alleviate the severity of ventricular fibrosis after ischemia/reperfusion (I/R) injury with improved cardiac function. This study provided a transcriptional and cellular landscape of CD34+ cells in normal and ischemic hearts and illustrated that the heterogeneous population of Cd34+ cell-derived cells served as crucial contributors to cardiac remodeling and function after the I/R injury, with their capacity to generate diverse cellular lineages.

Urokinase-Type Plasminogen Activator Receptor Regulates Prosurvival and Angiogenic Properties of Cardiac Mesenchymal Stromal Cells.

One of the largest challenges to the implementation of cardiac cell therapy is identifying selective reparative targets to enhance stem/progenitor cell therapeutic efficacy. In this work, we hypothesized that such a target could be an urokinase-type plasminogen activator receptor (uPAR)-a glycosyl-phosphatidyl-inositol-anchored membrane protein, interacting with urokinase. uPAR is able to form complexes with various transmembrane proteins such as integrins, activating intracellular signaling pathway and thus regulating multiple cell functions. We focused on studying the CD117+ population of cardiac mesenchymal progenitor cells (MPCs), expressing uPAR on their surface. It was found that the number of CD117+ MPCs in the heart of the uPAR-/- mice is lower, as well as their ability to proliferate in vitro compared with cells from wild-type animals. Knockdown of uPAR in CD117+ MPCs of wild-type animals was accompanied by a decrease in survival rate and Akt signaling pathway activity and by an increase in the level of caspase activity in these cells. That suggests the role of uPAR in supporting cell survival. After intramyocardial transplantation of uPAR(-) MPCs, reduced cell retention and angiogenesis stimulation were observed in mice with myocardial infarction model compared to uPAR(+) cells transplantation. Taken together, the present results appear to prove a novel mechanism of uPAR action in maintaining the survival and angiogenic properties of CD117+ MPCs. These results emphasize the importance of the uPAR as a potential pharmacological target for the regulation of reparative properties of myocardial mesenchymal progenitor cells.

Cadaveric Adipose-Derived Stem Cells for Regenerative Medicine and Research.

Advances in regenerative medicine have enabled the search for new solutions to current health problems in so far unexplored fields. Thus, we focused on cadaveric subcutaneous fat as a promising source of adipose-derived stem cells (ADSCs) that have potential to differentiate into different cell lines. With this aim, we isolated and characterized ADSCs from cadaveric samples with a postmortem interval ranging from 30 to 55 h and evaluated their ability to differentiate into chondrocytes or osteocytes. A commercial ADSC line was used as reference. Morphological and protein expression analyses were used to confirm the final stage of differentiation. Eight out of fourteen samples from patients were suitable to complete the whole protocol. Cadaveric ADSCs exhibited features of stem cells based upon several markers: CD29 (84.49 ± 14.07%), CD105 (94.38 ± 2.09%), and CD44 (99.77 ± 0.32%). The multiparametric assessment of differentiation confirmed the generation of stable lines of chondrocytes and osteocytes. In conclusion, we provide evidence supporting the feasibility of obtaining viable postmortem human subcutaneous fat ADSCs with potential application in tissue engineering and research fields.

Bone Marrow Mesenchymal Stem Cells for Heart Failure Treatment: A Systematic Review and Meta-Analysis.

AIM: Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the most well-studied and characterised stem cell types. This review was undertaken of the current available phase II/III randomised clinical trials (RCTs) that delivered BM-MSCs to treat patients with cardiomyopathy, and to assess their performance. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed during the systematic review and meta-analysis. Eligible studies were reviewed, and their data charted. To assess the efficacy of BM-MSCs, the outcome was improvement in left ventricular ejection fraction (LVEF) and 6-minute walking distance (6MWD). RESULTS: The pooled weighted mean difference (WMD) showed that BM-MSCs treatment improved the 6MWD by 27.86 m (95% CI 0.11-55.6 m) compared with the control groups. The pooled WMD showed that BM-MSCs treatment improved the LVEF by 6.37% (95% CI 5.48%-7.26%) compared with the control groups. CONCLUSION: BM-MSCs treatment is an effective intervention for managing patients with heart failure, but it requires larger and more robust clinical trials to support its routine use in clinics.

Identification of a novel m6A-related lncRNA pair signature for predicting the prognosis of gastric cancer patients.

BACKGROUND: Accumulating studies have demonstrated that lncRNAs play vital roles in the prognosis of gastric cancer (GC); however, the prognostic value of N6-methyladenosine-related lncRNAs has not been fully reported in GC. This study aimed to construct and validate an m6A-related lncRNA pair signature (m6A-LPS) for predicting the prognosis of GC patients. METHODS: GC cohort primary data were downloaded from The Cancer Genome Atlas. We analysed the coexpression of m6A regulators and lncRNAs to identify m6A-related lncRNAs. Based on cyclical single pairing along with a 0-or-1 matrix and least absolute shrinkage and selection operator-penalized regression analyses, we constructed a novel prognostic signature of m6A-related lncRNA pairs with no dependence upon specific lncRNA expression levels. All patients were divided into high-risk and low-risk group based on the median risk score. The predictive reliability was evaluated in the testing dataset and whole dataset with receiver operating characteristic (ROC) curve analysis. Gene set enrichment analysis was used to identify potential pathways. RESULTS: Fourteen m6A-related lncRNA pairs consisting of 25 unique lncRNAs were used to construct the m6A-LPS. Kaplan-Meier analysis showed that the high-risk group had poor prognosis. The area under the curve for 5-year overall survival was 0.906, 0.827, and 0.882 in the training dataset, testing dataset, and whole dataset, respectively, meaning that the m6A-LPS was highly accurate in predicting GC patient prognosis. The m6A-LPS served as an independent prognostic factor for GC patients after adjusting for other clinical factors (p < 0.05). The m6A-LPS had more accuracy and a higher ROC value than other prognostic models for GC. Functional analysis revealed that high-risk group samples mainly showed enrichment of extracellular matrix receptor interactions and focal adhesion. Moreover, N-cadherin and vimentin, known biomarkers of epithelial-mesenchymal transition, were highly expressed in high-risk group samples. The immune infiltration analysis showed that resting dendritic cells, monocytes, and resting memory CD4 T cells were significantly positively related to the risk score. Thus, m6A-LPS reflected the infiltration of several types of immune cells. CONCLUSIONS: The signature established by pairing m6A-related lncRNAs regardless of expression levels showed high and independent clinical prediction value in GC patients.

Melatonin Promotes Antler Growth by Accelerating MT1-Mediated Mesenchymal Cell Differentiation and Inhibiting VEGF-Induced Degeneration of Chondrocytes.

The sika deer is one type of seasonal breeding animal, and the growth of its antler is affected by light signals. Melatonin (MLT) is a neuroendocrine hormone synthesized by the pineal gland and plays an important role in controlling the circadian rhythm. Although the MLT/MT1 (melatonin 1A receptor) signal has been identified during antler development, its physiological function remains almost unknown. The role of MLT on antler growth in vivo and in vitro is discussed in this paper. In vivo, MLT implantation was found to significantly increase the weight of antlers. The relative growth rate of antlers showed a remarkable increased trend as well. In vitro, the experiment showed MLT accelerated antler mesenchymal cell differentiation. Further, results revealed that MLT regulated the expression of Collage type II (Col2a) through the MT1 binding mediated transcription of Yes-associated protein 1 (YAP1) in antler mesenchymal cells. In addition, treatment with vascular endothelial growth factor (VEGF) promoted chondrocytes degeneration by downregulating the expression of Col2a and Sox9 (SRY-Box Transcription Factor 9). MLT effectively inhibited VEGF-induced degeneration of antler chondrocytes by inhibiting the Signal transducers and activators of transcription 5/Interleukin-6 (STAT5/IL-6) pathway and activating the AKT/CREB (Cyclin AMP response-element binding protein) pathway dependent on Sox9 expression. Together, our results indicate that MLT plays a vital role in the development of antler cartilage.

Hematopoietic-Mesenchymal Signals Regulate the Properties of Mesenchymal Stem Cells.

It is well known that the properties of hematopoietic stem/progenitor cells (HSCs), such as their self-renewal ability and multipotency, are maintained through interactions with mesenchymal stem/stromal cells (MSCs). MSCs are rare cells that are present in the bone marrow and are useful for clinical applications due to their functional ability. To obtain the necessary number of cells, MSCs must be cultured to expand, but this causes a remarkable decrease in stem cell properties, such as multipotency and proliferation ability. In this study, we show that the c-Mpl signal, which is related to the maintenance of hematopoietic stem cells, has an important effect on the proliferation and differentiation ability of MSCs. Utilizing a co-culture system comprising MSCs and HSCs, it is suggested that signaling from hematopoietic cells to MSCs supports cell proliferation. Interestingly, the enhanced proliferation ability of the HSCs was decreased in c-Mpl knock-out HSCs (c-Mpl-KO). In addition, the MSCs co-cultured with c-Mpl-KO HSCs had reduced MSC marker expression (PDGFRa and Sca-1) compared to the MSCs co-cultured with c-Mpl-wild-type HSCs. These results suggest that a hematopoietic-mesenchymal signal exists, and that the state of the HSCs is important for the stability of MSC properties.

Cellular mechanisms of frontal bone development in spotted gar (Lepisosteus oculatus).

BACKGROUND: The cellular and molecular mechanisms initiating vertebrate cranial dermal bone formation is a conundrum in evolutionary and developmental biology. Decades of studies have determined the developmental processes of cranial dermal bones in various vertebrates and identified possible inducers of dermal bone. However, evolutionarily derived characters of current experimental model organisms, such as non-homologous frontal bones between teleosts and sarcopterygians, hinder investigations of ancestral and conserved mechanisms of vertebrate cranial dermal bone induction. Thus, investigating such mechanisms with animals diverging at evolutionarily informative phylogenetic nodes is imperative. RESULTS: We investigated the cellular foundations of skull frontal bone formation in the spotted gar Lepisosteus oculatus, a basally branching non-teleost actinopterygian. Whole-mount bone and cartilage staining and hematoxylin-eosin section staining revealed that mesenchymal cell condensations in the frontal bone of spotted gar develop in close association with the underlying cartilage. We also identified novel aspects of frontal bone formation: enrichment of F-actin, cellular membranes, and E-cadherin in condensing cells, and extension of podia-like structures from osteoblasts to the frontal bone, which may be responsible for bone mineral transport. CONCLUSION: This study highlights the process of frontal bone formation with dynamic architectural changes of mesenchymal cells in spotted gar, an emerging non-teleost fish model system, illuminating supposedly ancestral and likely conserved developmental mechanisms of skull bone formation among vertebrates.

Expression of serum response factor in the lung mesenchyme is essential for development of pulmonary fibrosis.

Extracellular matrix deposition characterizes idiopathic pulmonary fibrosis (IPF) and is orchestrated by myofibroblasts. The lung mesenchyme is an essential source of myofibroblasts in pulmonary fibrosis. Although the transcription factor serum response factor (SRF) has shown to be critical in the process of myofibroblast differentiation, its role in development of pulmonary fibrosis has not been determined in vivo. In this study, we observed that SRF expression localized to mesenchymal compartments, areas of dense fibrosis, and fibroblastic foci in human (IPF and normal) and bleomycin-treated mouse lungs. To determine the role of mesenchymal SRF in pulmonary fibrosis, we utilized a doxycycline-inducible, Tbx4 lung enhancer (Tbx4LE)-driven Cre-recombinase to disrupt SRF expression in the lung mesenchyme in vivo. Doxycycline-treated Tbx4LE-rtTA/TetO-Cre/tdTom/SRFf,f (and controls) were treated with a single intratracheal dose of bleomycin to induce pulmonary fibrosis and examined for lung mesenchymal expansion, pulmonary fibrosis, and inflammatory response. Bleomycin-treated Tbx4LE-rtTA/TetO-Cre/tdTom/SRFf,f mice showed decreased numbers of Tbx4LE-positive lung mesenchymal cells (LMCs) and collagen accumulation (via hydroxyproline assay) compared with controls. This effect was associated with SRF-null LMCs losing their proliferative and myofibroblast differentiation potential compared with SRF-positive controls. Together, these data demonstrate that SRF plays a critical role in LMC myofibroblast expansion during bleomycin-induced pulmonary fibrosis. This sets the stage for pharmacological strategies that specifically target SRF in the lung mesenchyme as a potential means of treating pulmonary fibrosis.

Molecular structure, gene expression and functional role of WFDC1 in angiogenesis and cancer.

Whey acidic proteins (WAP) perform a diverse range of important biological functions, including proteinase activity, calcium transport and bacterial growth. The WAP four-disulphide core domain protein 1 (WFDC1) gene (also called PS20), encodes the 20 kDa prostate stromal protein (ps20), which is a member of the WAP-type four-disulphide core domain family of proteins, and exhibits characteristics of serine protease inhibitors, such as elafin and secretory leukocyte protease inhibitor. Molecular structural analysis reveals that ps20 consists of four-disulphide bonds formed by eight cysteine residues located at the carboxyl terminus of the protein. Wfdc1-null mice were found to display no overt developmental phenotype, suggesting a dispensable role in organ growth and development. However, WFDC1 was able to mediate endothelial cell migration and pericyte stabilization, which are vital for the formation of functional vascular structures. WFDC1 was also found to be downregulated in cancers and exhibited a regulatory effect on cell proliferation. In addition, it was involved in the modulation of memory T cells during human immunodeficiency virus infection. Gaining a solid understanding of the mechanisms by which WFDC1 regulates tissue homeostasis and disease processes, in a tissue specific manner, will be an important move towards the development of WFDC1/ps20 as potential therapeutic targets.

Histological, Histochemical, and Ultrastructural Approach to the Ductus Deferens in Male Nile Monitor Lizard (Varanus niloticus).

The ductus deferens is a fundamental part of the male genital tract and the continuation of the epididymal duct. As a male secondary sex organ, the ductus deferens plays a crucial role in the nourishment, storage, and maturation of spermatozoa. Some studies have provided information about the ductus deferens structure in reptiles; however, the full description of the ductus deferens remains to be clarified. The current study aimed to describe the Nile monitor lizard (Varanus niloticus) ductus deferens from histological, histochemical, and ultrastructural perspectives. The results revealed that the ductus deferens is formed histologically from two main cell types: principal and basal. The principal cells were tall and filled with periodic acid Schiff (+)/alcian blue (−) cytoplasmic granules. The basal cells were found just above the basement membrane. By transmission electron microscopy, the principal cells exhibited typical protein-secreting cell features. Additionally, some intraepithelial cells, such as halo cells, undifferentiated mesenchymal cells, and agranular leukocytes, were identified. This study presents the first detailed description of the Varanus niloticus ductus deferens. Further immunohistochemical studies are required to explore the function(s) of the cellular components.