Follistatin-like-1, a diffusible mesenchymal factor determines the fate of epithelium

In silico screening system based on a transcription factors regulatory network only using transcriptomic data

In this study, we developed a method to identify core transcription factors (TFs) involved in differentiation using only comprehensive gene analysis. The theory of in silico screening using TFs regulatory network analysis (ISNA) required the following requirements: (1) estimating promoter regions, (2) constructing TFs regulatory network (TRN) relationships using the nucleotide sequence information in the promoters and score matrices derived from TF consensus sequences, and (3) identifying candidate core TFs by determining dissociation constants (Kd values) within the relationships of TRN. ISNA demonstrated the ability to predict the core TFs involved in the endothelial-to-mesenchymal transition of human umbilical vein endothelial cell (HUVEC) and the differentiation of human embryonic stem cells into mesodermal cells. Using ISNA, we identified HMGA2 as a novel core TF in uterine epithelium. Notably, HMGA2 expression was predominantly detected in uterine epithelium, where it regulated cell proliferation in response to estrogen. These findings highlight ISNA's potential to identify core TFs based on transcriptomic data.

Follistatin-like protein 1: Implications for renal disease progression

Renal diseases, including glomerulonephritis, acute kidney injury, chronic kidney failure, and kidney tumors are all current global health challenges. Lesions in other systems can cause renal diseases and can affect other systems or even the whole body. Despite ongoing advancements in pharmaceutical and technological innovations, the prognosis for end-stage renal disease, encompassing renal failure and tumors, continues to be bleak. Follistatin-like protein 1 (FSTL1) is a secreted glycoprotein produced mainly by mesenchymal cells. FSTL1 is a glycoprotein that belongs to the family of secreted, cysteine-rich acidic proteins (SPARC). It plays a pivotal role in cell survival, proliferation, differentiation, and migration, as well as in modulating inflammation and immune responses. Research has shown that FSTL1 plays a crucial role in the onset and progression of renal diseases. This review explores the functions and underlying mechanisms of FSTL1 in kidney pathology. SIGNIFICANCE STATEMENT: This review highlights the pivotal role of FSTL1 in renal diseases, particularly its involvement in renal fibrosis, inflammation, and ischemia-reperfusion injury. By elucidating its dual roles across different pathologies, this work underscores FSTL1's potential as both a biomarker and a therapeutic target, offering novel insights for managing chronic kidney disease and associated complications.

Salivary Gland Tissue Recombination Can Modify Cell Fate

Although mesenchyme is essential for inducing the epithelium of ectodermal organs, its precise role in organ-specific epithelial fate determination remains poorly understood. To elucidate the roles of tissue interactions in cellular differentiation, we performed single-cell RNA sequencing and imaging analyses on recombined tissues, where mesenchyme and epithelium were switched ex vivo between two types of embryonic mouse salivary glands: the parotid gland (a serous gland) and the submandibular gland (a predominantly mucous gland). We found partial induction of molecules that define gland-specific acinar and myoepithelial cells in recombined salivary epithelium. The parotid epithelium recombined with submandibular mesenchyme began to express mucous acinar genes not intrinsic to the parotid gland. While myoepithelial cells do not normally line parotid acini, newly induced myoepithelial cells densely populated recombined parotid acini. However, mucous acinar and myoepithelial markers continued to be expressed in submandibular epithelial cells recombined with parotid mesenchyme. Consequently, some epithelial cells appeared to be plastic, such that their fate could still be modified in response to mesenchymal signaling, whereas other epithelial cells appeared to be already committed to a specific fate. We also discovered evidence for bidirectional induction: transcriptional changes were observed not only in the epithelium but also in the mesenchyme after heterotypic tissue recombination. For example, parotid epithelium induced the expression of muscle-related genes in submandibular fibroblasts that began to mimic parotid fibroblast gene expression. These studies provide the first comprehensive unbiased molecular characterization of tissue recombination approaches exploring the regulation of cell fate.

Single-cell transcriptomic profiling of the neonatal oviduct and uterus reveals new insights into upper Müllerian duct regionalization

The upper Müllerian duct (MD) is patterned and specified into two morphologically and functionally distinct organs, the oviduct and uterus. It is known that this regionalization process is instructed by inductive signals from the adjacent mesenchyme. However, the interaction landscape between epithelium and mesenchyme during upper MD development remains largely unknown. Here, we performed single-cell transcriptomic profiling of mouse neonatal oviducts and uteri at the initiation of MD epithelial differentiation (postnatal day 3). We identified major cell types including epithelium, mesenchyme, pericytes, mesothelium, endothelium, and immune cells in both organs with established markers. Moreover, we uncovered region-specific epithelial and mesenchymal subpopulations and then deduced region-specific ligand-receptor pairs mediating mesenchymal-epithelial interactions along the craniocaudal axis. Unexpectedly, we discovered a mesenchymal subpopulation marked by neurofilaments with specific localizations at the mesometrial pole of both the neonatal oviduct and uterus. Lastly, we analyzed and revealed organ-specific signature genes of pericytes and mesothelial cells. Taken together, our study enriches our knowledge of upper MD development, and provides a manageable list of potential genes, pathways, and region-specific cell subtypes for future functional studies.

Single-cell transcriptomic profiling of the neonatal oviduct and uterus reveals new insights into upper Müllerian duct regionalization

The upper Müllerian duct (MD) is patterned and specified into two morphologically and functionally distinct organs, the oviduct and uterus. It is known that this regionalization process is instructed by inductive signals from the adjacent mesenchyme. However, the interaction landscape between epithelium and mesenchyme during upper MD development remains largely unknown. Here, we performed single-cell transcriptomic profiling of mouse neonatal oviducts and uteri at the initiation of MD epithelial differentiation (postnatal day 3). We identified major cell types including epithelium, mesenchyme, pericytes, mesothelium, endothelium, and immune cells in both organs with established markers. Moreover, we uncovered region-specific epithelial and mesenchymal subpopulations and then deduced region-specific ligand-receptor pairs mediating mesenchymal-epithelial interactions along the craniocaudal axis. Unexpectedly, we discovered a mesenchymal subpopulation marked by neurofilaments with specific localizations at the mesometrial pole of both the neonatal oviduct and uterus. Lastly, we analyzed and revealed organ-specific signature genes of pericytes and mesothelial cells. Taken together, our study enriches our knowledge of upper Müllerian duct development, and provides a manageable list of potential genes, pathways, and region-specific cell subtypes for future functional studies.

Extracellular matrix components and elasticity regulate mouse vaginal epithelial differentiation induced by mesenchymal cells†

Oviduct, uterus, and vagina are derived from Müllerian ducts. But only in the vagina, the epithelium differentiates into stratified layers. Organ-specific secreted factors derived from the stroma of a neonatal mouse induce epithelial differentiation in the female reproductive tracts. However, the effects of the components and mechanical property of extracellular matrix (ECM) on the regulation of gene expression in the mesenchymal cells of neonatal stroma and differentiation of epithelium in the female reproductive tracts have been overlooked. In the present study, we have developed a simple 3D neonatal vaginal model using clonal cell lines to study the effect of ECM's components and stiffness on the epithelial stratification. Transcriptome analysis was performed by DNA-microarray to identify the components of ECM involved in the differentiation of vaginal epithelial stratification. The knockdown experiment of the candidate genes relating to vaginal epithelial stratification was focused on fibromodulin (Fmod), a collagen cross-linking protein. FMOD was essential for the expression of Bmp4, which encodes secreted factors to induce the epithelial stratification of vaginal mesenchymal cells. Furthermore, stiffer ECM as a scaffold for epithelial cells is necessary for vaginal epithelial stratification. Therefore, the components and stiffness of ECM are both crucial for the epithelial stratification in the neonatal vagina.

Biophysical and biochemical properties of Deup1 self-assemblies: a potential driver for deuterosome formation during multiciliogenesis

The deuterosome is a non-membranous organelle involved in large-scale centriole amplification during multiciliogenesis. Deuterosomes are specifically assembled during the process of multiciliogenesis. However, the molecular mechanisms underlying deuterosome formation are poorly understood. In this study, we investigated the molecular properties of deuterosome protein 1 (Deup1), an essential protein involved in deuterosome assembly. We found that Deup1 has the ability to self-assemble into macromolecular condensates both in vitro and in cells. The Deup1-containing structures formed in multiciliogenesis and the Deup1 condensates self-assembled in vitro showed low turnover of Deup1, suggesting that Deup1 forms highly stable structures. Our biochemical analyses revealed that an increase of the concentration of Deup1 and a crowded molecular environment both facilitate Deup1 self-assembly. The self-assembly of Deup1 relies on its N-terminal region, which contains multiple coiled coil domains. Using an optogenetic approach, we demonstrated that self-assembly and the C-terminal half of Deup1 were sufficient to spatially compartmentalize centrosomal protein 152 (Cep152) and polo like kinase 4 (Plk4), master components for centriole biogenesis, in the cytoplasm. Collectively, the present data suggest that Deup1 forms the structural core of the deuterosome through self-assembly into stable macromolecular condensates.This article has an associated First Person interview with the first author of the paper.

New frontiers of developmental endocrinology opened by researchers connecting irreversible effects of sex hormones on developing organs

In the early 1960's, at Professor Bern's laboratory, University of California, Berkeley) in the US, Takasugi discovered ovary-independent, persistent vaginal changes in mice exposed neonatally to estrogen, which resulted in vaginal cancer later in life. Reproductive abnormalities in rodents were reported as a result of perinatal exposure to various estrogenic chemicals. Ten years later, vaginal cancers were reported in young women exposed in utero to the synthetic estrogen diethylstilbestrol (DES) and this has been called the "DES syndrome". The developing organism is particularly sensitive to developmental exposure to estrogens inducing long-term changes in various organs including the reproductive organs. The molecular mechanism underlying the persistent vaginal changes induced by perinatal estrogen exposure was partly demonstrated. Persistent phosphorylation and sustained expression of EGF-like growth factors, lead to estrogen receptor α (ESR1) activation, and then persistent vaginal epithelial cell proliferation. Agents which are weakly estrogenic by postnatal criteria may have major developmental effects, especially during a critical perinatal period. The present review outlines various studies conducted by four generations of investigators all under the influence of Prof. Bern. The studies include reports of persistent changes induced by neonatal androgen exposure, analyses of estrogen responsive genes, factors determining epithelial differentiation in the Müllerian duct, ESR and growth factor signaling, and polyovular follicles in mammals. This review is then expanded to the studies on the effects of environmental estrogens on wildlife and endocrine disruption in Daphnids.

Targeting FSTL1 for Multiple Fibrotic and Systemic Autoimmune Diseases

Follistatin-like 1 (FSTL1) is a matricellular protein that is upregulated during development and disease, including idiopathic pulmonary fibrosis (IPF), keloid, and arthritis. The profibrotic and pro-inflammatory roles of FSTL1 have been intensively studied during the last several years, as well as in this report. We screened and identified epitope-specific monoclonal neutralizing antibodies (nAbs) to functionally block FSTL1. FSTL1 nAbs attenuated bleomycin-induced pulmonary and dermal fibrosis in vivo and transforming growth factor (TGF)-β1-induced dermal fibrosis ex vivo in human skin. In addition, FSTL1 nAbs significantly reduced existing lung fibrosis and skin fibrosis in experimental models. FSTL1 nAbs exerted their potent antifibrotic effects via reduced TGF-β1 responsiveness and subsequent myofibroblast activation and extracellular matrix production. We also observed that FSTL1 nAbs attenuated the severity of collagen-induced arthritis in mice, which was accompanied by reduced inflammatory responses in vitro. Our findings suggest that FSTL1 nAbs are a promising new therapeutic strategy for the treatment of multiple organ fibrosis and systemic autoimmune diseases.

Developmental mechanisms regulating the formation of smooth muscle layers in the mouse uterus†

Uterine smooth muscle cells differentiate from mesenchymal cells, and gap junctions connect the muscle cells in the myometrium. At the neonatal stage, a uterine smooth muscle layer is situated away from the epithelium when smooth muscle cells are grafted near the epithelium, suggesting that the epithelium plays an important role in differentiation, proliferation, and/or migration of smooth muscle cells. In this study, developmental mechanisms regulating the formation of the smooth muscle layers in the mouse uterus were analyzed using an in vitro culture model. Differentiation of smooth muscle cells occurs at a neonatal stage because ACTA2 gene expression was increased at the outer layer, and GJA1 was not expressed in cellular membranes of uterine smooth muscle cells by postnatal day 15. To analyze the effects of the epithelium on the differentiation of smooth muscle cells, a bulk uterine mesenchymal cell line was established from p53−/− mice at postnatal day 3 (P3US cells). Co-culture with Müllerian ductal epithelial cells (E1 cells) induced repulsive migration of ACTA2-positive cells among bulk P3US cells from E1 cells, but it had no effects on the migration of any of 100% ACTA2-positive or negative smooth muscle cell lines cloned from P3US cells. Thus, uterine epithelial cells indirectly affected the repulsive migration of smooth muscle cells via mesenchymal cells. Conditioned medium by E1 cells inhibited differentiation into smooth muscle cells of clonal cells established from P3US cells. Therefore, the uterine epithelium inhibits the differentiation of stem-like progenitor mesenchymal cells adjacent to the epithelium into smooth muscle cells.

FSTL-1 Attenuation Causes Spontaneous Smoke-Resistant Pulmonary Emphysema

Rationale: The role of FSTL-1 (follistatin-like 1) in lung homeostasis is unknown.Objectives: We aimed to define the impact of FSTL-1 attenuation on lung structure and function and to identify FSTL-1-regulated transcriptional pathways in the lung. Further, we aimed to analyze the association of FSTL-1 SNPs with lung disease.Methods: FSTL-1 hypomorphic (FSTL-1 Hypo) mice underwent lung morphometry, pulmonary function testing, and micro-computed tomography. Fstl1 expression was determined in wild-type lung cell populations from three independent research groups. RNA sequencing of wild-type and FSTL-1 Hypo mice identified FSTL-1-regulated gene expression, followed by validation and mechanistic in vitro examination. FSTL1 SNP analysis was performed in the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) cohort.Measurements and Main Results: FSTL-1 Hypo mice developed spontaneous emphysema, independent of smoke exposure. Fstl1 is highly expressed in the lung by mesenchymal and endothelial cells but not immune cells. RNA sequencing of whole lung identified 33 FSTL-1-regulated genes, including Nr4a1, an orphan nuclear hormone receptor that negatively regulates NF-κB (nuclear factor-κB) signaling. In vitro, recombinant FSTL-1 treatment of macrophages attenuated NF-κB p65 phosphorylation in an Nr4a1-dependent manner. Within the COPDGene cohort, several SNPs in the FSTL1 region corresponded to chronic obstructive pulmonary disease and lung function.Conclusions: This work identifies a novel role for FSTL-1 protecting against emphysema development independent of smoke exposure. This FSTL-1-deficient emphysema implicates regulation of immune tolerance in lung macrophages through Nr4a1. Further study of the mechanisms involving FSTL-1 in lung homeostasis, immune regulation, and NF-κB signaling may provide additional insight into the pathophysiology of emphysema and inflammatory lung diseases.

A clonal stem cell line established from a mouse mammary placode with ability to generate functional mammary glands

The mammary gland develops from the placode at ectodermal invagination. The rudimentary parenchyma (mammary bud) develops mammary trees and alveolar structures, suggesting that the mammary bud consists of stem/progenitor cells. Here, we established a clonal stem cell line from a mammary bud of a p53 null female embryo at day 14.5. FP5-3-1 line was a homogeneous cell population with polygonal epithelial morphology and spontaneously became heterogeneous during passages. Recloning gave rise to four sublines; three sublines have basal epithelial property and one subline has luminal epithelial property. The former sublines generate functional mammary glands when injected into cleared fat pads and the latter subline does not. The cell lines also express many stemness-related genes. The clonal cell lines established in the present study are shown to be mammary stem cells and not tumorigenic. They provide useful models for normal and tumor biology of the mammary gland in vivo and in vitro.

Follistatin-like 1 in development and human diseases

Follistatin-like 1 (FSTL1) is a secreted glycoprotein displaying expression changes during development and disease, among which cardiovascular disease, cancer, and arthritis. The cardioprotective role of FSTL1 has been intensively studied over the last years, though its mechanism of action remains elusive. FSTL1 is involved in multiple signaling pathways and biological processes, including vascularization and regulation of the immune response, a feature that complicates its study. Binding to the DIP2A, TLR4 and BMP receptors have been shown, but other molecular partners probably exist. During cancer progression and rheumatoid arthritis, controversial data have been reported with respect to the proliferative, apoptotic, migratory, and inflammatory effects of FSTL1. This controversy might reside in the extensive post-transcriptional regulation of FSTL1. The FSTL1 primary transcript also encodes for a microRNA (miR-198) in primates and multiple microRNA-binding sites are present in the 3'UTR. The switch between expression of the FSTL1 protein and miR-198 is an important regulator of tumour metastasis and wound healing. The glycosylation state of FSTL1 is a determinant of biological activity, in cardiomyocytes the glycosylated form promoting proliferation and the non-glycosylated working anti-apoptotic. Moreover, the glycosylation state shows differences between species and tissues which might underlie the differences observed in in vitro studies. Finally, regulation at the level of protein secretion has been described.

Decrease of FSTL1-BMP4-Smad signaling predicts poor prognosis in lung adenocarcinoma but not in squamous cell carcinoma

Follistatin-related protein 1 (FSTL1) plays a critical role in lung development through regulating BMP4-p-Smad1/5/8-Smad4 pathway. Regarding that many developmental pathways in embryogenesis are dysregulated in cancer, we aim to unravel the role of FSTL1-BMP4-Smad pathway in lung cancer. Our results showed low FSTL1 immunoexpression was significantly correlated with poor prognosis while patients with low BMP4 or low Smad4 immunoexpression showed a trend toward poor prognosis. When stratified by different histological types, low FSTL1, BMP4, and Smad4 expression retained their trends in predicting poor prognosis in lung adenocarcinoma (LUAD) but not in lung squamous cell carcinoma (SCC). Low FSTL1, BMP4, and Smad4 expression were more frequently observed in LUAD patients with smoking history. To determine smoking effect on FSTL1, normal cell BEAS2B and lung cancer cell lines was treated with nicotine and the results showed nicotine increased the proliferation of these cells. Interestingly, FSTL1 attenuated nicotine-induced BEAS2B and lung cancer cell line proliferation. Altogether, low FSTL1, BMP4, and Smad4 expression significantly correlated with poor prognosis in LUAD but not in SCC. Frequent decrease of FSTL1 expression in smokers LUAD further indicates its importance and therapeutic potential for lung cancer patients with specific subtypes. FSTL1 may prevent nicotine-induced lung cancer cell proliferation.

Follistatin-like protein 1 modulates IL-17 signaling via IL-17RC regulation in stromal cells

Follistatin-like protein 1 (FSTL-1) possesses several newly identified roles in mammalian biology, including IL-17 driven inflammation, though the mechanism underlying FSTL-1 influence on IL-17 mediated cytokine production is unknown. Using parallel in vitro bone marrow stromal cell models of FSTL-1 suppression we employed unbiased microarray analysis to identify FSTL-1 regulated genes and pathways that could influence IL-17 dependent production of IL-6 and G-CSF. We discovered that FSTL-1 modulates Il17rc gene expression. Specifically, FSTL-1 was necessary for Il17rc gene transcription, IL-17RC surface protein expression and IL-17-dependent cytokine production. This work identifies a mechanism by which FSTL-1 influences IL-17 driven inflammatory signalingin vitro and reveals a novel function for FSTL-1, as a modulator of gene expression. Thus, enhanced understanding of the interplay between FSTL-1 and IL-17 mediated inflammation may provide insight into potential therapeutic targets of IL-17 mediated diseases and warrants ongoing study of in vivo models and clinical scenarios of FSTL-1-influenced diseases.

Mitotic cell death caused by follistatin-like 1 inhibition is associated with up-regulated Bim by inactivated Erk1/2 in human lung cancer cells

Follistatin-like 1 (FSTL1) was identified as a novel pro-inflammatory protein showing high-level expression in rheumatoid arthritis. The protective effect of FSTL1 via the inhibition of apoptosis was reported in myocardial injury. However, the functional mechanism of FSTL1 in cancer is poorly characterized, and its proliferative effects are ambiguous. Here, we examined the effects of FSTL1 on cellular proliferation and cell cycle checkpoints in lung cancer cells. FSTL1 inhibition induced the cellular portion of G2/M phase in human lung cancer cells via the accumulation of regulators of the transition through the G2/M phase, including the cyclin-dependent kinase 1 (Cdk1)-cyclin B1 complex. An increase in histone H3 phosphorylation (at Ser10), another hallmark of mitosis, indicated that the knockdown of FSTL1 in lung cancer cells stimulated a mitotic arrest. After that, apoptosis was promoted by the activation of caspase-3 and -9. Protein level of Bim, a BH3 domain-only, pro-apoptotic member and its isoforms, BimL, BimS, and BimEL were up-regulated by FSTL1 inhibition. Degradation of Bim was blocked in FSTL1-knockdown cells by decreased phosphorylation of Bim. Increased BimEL as well as decreased phosphorylated Erk1/2 is essential for cell death by FSTL1 inhibition in NCI-H460 cells. Taken together, our results suggest that the knockdown of FSTL1 induces apoptosis through a mitotic arrest and caspase-dependent cell death. FSTL1 plays the important roles in cellular proliferation and apoptosis in lung cancer cells, and thus can be a new target for lung cancer treatment.

Role of extracellular vesicles in the interaction between epithelial and mesenchymal cells during oviductal ciliogenesis

Extracellular vesicles (EVs) have been shown to transport miRNA, mRNA and protein, suggesting that they are new communication mediators. Diffusible mesenchymal factors determine the fate of Műllerian epithelial cells into oviductal ciliated cells. In the present study, we investigated whether EVs mediate the communication in the epithelial-mesenchymal interaction during oviductal ciliogenesis. EVs were isolated from cells of oviductal mesenchymal cell line (S1 cells) and characterized by TEM and expression of exosomal marker CD81. CD81 protein was also detected in oviductal mesenchyme, suggesting that CD81-expressing exosomes may be secreted from oviductal mesenchyme, as well as S1 cells. β-actin, Gapdh and Vimentin mRNAs and miRNAs were detected in the exosomes. mRNA in S1 cells was able to be transported into cells of Műllerian epithelial cell line (E1 cells) via the exosomes. The effects of exosomes derived from S1 cells on ciliogenesis of E1 cells were analyzed by in vitro models. Culture with exosomes increased the number of ciliated cells in E1 cells. These results suggest that exosomes derived from mesenchymal cells modulate the oviductal ciliogenesis and open new avenues for developmental study of EVs.

Retinoic acid signaling determines the fate of uterine stroma in the mouse Müllerian duct

The Müllerian duct develops into the oviduct, uterus, and vagina, all of which are quite distinct in their morphology and function. The epithelial fate of these female reproductive organs in developing mice is determined by factors secreted from the stroma; however, how stromal differentiation occurs in the female reproductive organs derived from the Müllerian duct is still unclear. In the present study, roles of retinoic acid (RA) signaling in developing female reproductive tracts were investigated. Retinol dehydrogenase 10 (RDH10) and aldehyde dehydrogenase family 1 subfamily A2 (ALDH1A2) mRNAs and proteins and transactivation activity of endogenous RA were found in the stroma of proximal Müllerian ducts and gradually decreased from the proximal to caudal regions in fetal mice. In organ-cultured Müllerian ducts, retinaldehyde or RA treatment induced uterine epithelial differentiation, defined as a layer of columnar epithelial cells negative for oviductal and vaginal epithelial markers. In contrast, inhibition of RA receptor (RAR) signaling induced vaginal epithelial differentiation, characterized as vaginal epithelial marker genes-positive stratified epithelium. Grafting experiments of the organ-cultured Müllerian duct revealed irreversible epithelial fate determination. Although RAR did not directly bind to the homeobox A10 (Hoxa10) promoter region, RA-RAR signaling stimulated Hoxa10 expression. Thus, RA-RAR signaling in the Müllerian duct determines the fate of stroma to form the future uterus and vagina.

Fstl1 is involved in the regulation of radial glial scaffold development

Background

Radial glial cells (RGCs), the instructive scaffolds for neuronal migration, are well characterized by their unique morphology and polarization; these cells extend elongated basal processes to the pial basement membrane (BM) and parallel to one another. However, little is known about the mechanisms that underlie the developmental regulation and maintenance of this unique morphology.

Results

Here, by crossing Fstl1^fl/fl mice with an EIIa-Cre line, we identified a new role for the secreted glycoprotein Follistatin like-1 (FSTL1). The ablation of Fstl1 in both of its cortical expression domains, the ventricular zone (VZ) and the pia mater, resulted in RGC morphologic disruption; basal processes were not parallel to each other, and endfeet exhibited greater density and branching. However, Fstl1 deletion in only the VZ in the Emx1^IREScre; Fstl1^fl/fl line did not affect RGC morphology, indicating that FSTL1 derived from the pia mater might be more important for RGC morphology. In addition, upper-layer projection neurons, not deeper-layer projection neurons, failed to reach their appropriate positions. We also found that BMP, AKT/PKB, Cdc42, GSK3β, integrin and reelin signals, which have previously been reported to regulate RGC development, were unchanged, indicating that Fstl1 may function through a unique mechanism.

Conclusions

In the present study, we identified a new role for FSTL1 in the development of radial glial scaffolds and the neuronal migration of upper-layer projection neurons. Our findings will improve understanding of the regulation of RGC development and neuronal migration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13041-015-0144-8) contains supplementary material, which is available to authorized users.

Fstl1 Promotes Asthmatic Airway Remodeling by Inducing Oncostatin M

Chronic asthma is associated with airway remodeling and decline in lung function. In this article, we show that follistatin-like 1 (Fstl1), a mediator not previously associated with asthma, is highly expressed by macrophages in the lungs of humans with severe asthma. Chronic allergen-challenged Lys-Cre(tg) /Fstl1(Δ/Δ) mice in whom Fstl1 is inactivated in macrophages/myeloid cells had significantly reduced airway remodeling and reduced levels of oncostatin M (OSM), a cytokine previously not known to be regulated by Fstl1. The importance of the Fstl1 induction of OSM to airway remodeling was demonstrated in murine studies in which administration of Fstl1 induced airway remodeling and increased OSM, whereas administration of an anti-OSM Ab blocked the effect of Fstl1 on inducing airway remodeling, eosinophilic airway inflammation, and airway hyperresponsiveness, all cardinal features of asthma. Overall, these studies demonstrate that the Fstl1/OSM pathway may be a novel pathway to inhibit airway remodeling in severe human asthma.

Microarray analysis of genes involved with shell strength in layer shell gland at the early stage of active calcification

The objective of this study was to get a comprehensive understanding of how genes in chicken shell gland modulate eggshell strength at the early stage of active calcification. Four 32-week old of purebred Xianju hens with consistent high or low shell breakage strength were grouped into two pairs. Using Affymetrix Chicken Array, a whole-transcriptome analysis was performed on hen’s shell gland at 9 h post oviposition. Gene ontology enrichment analysis for differentially expressed (DE) transcripts was performed using the web-based GOEAST, and the validation of DE-transcripts was tested by qRT-PCR. 1,195 DE-transcripts, corresponding to 941 unique genes were identified in hens with strong eggshell compared to weak shell hens. According to gene ontology annotations, there are 77 DE-transcripts encoding ion transporters and secreted extracellular matrix proteins, and at least 26 DE-transcripts related to carbohydrate metabolism or post-translation glycosylation modification; furthermore, there are 88 signaling DE-transcripts. GO term enrichment analysis suggests that some DE-transcripts mediate reproductive hormones or neurotransmitters to affect eggshell quality through a complex suite of biophysical processes. These results reveal some candidate genes involved with eggshell strength at the early stage of active calcification which may facilitate our understanding of regulating mechanisms of eggshell quality.

Predicting targeted drug combinations based on Pareto optimal patterns of coexpression network connectivity

Background

Molecularly targeted drugs promise a safer and more effective treatment modality than conventional chemotherapy for cancer patients. However, tumors are dynamic systems that readily adapt to these agents activating alternative survival pathways as they evolve resistant phenotypes. Combination therapies can overcome resistance but finding the optimal combinations efficiently presents a formidable challenge. Here we introduce a new paradigm for the design of combination therapy treatment strategies that exploits the tumor adaptive process to identify context-dependent essential genes as druggable targets.

Methods

We have developed a framework to mine high-throughput transcriptomic data, based on differential coexpression and Pareto optimization, to investigate drug-induced tumor adaptation. We use this approach to identify tumor-essential genes as druggable candidates. We apply our method to a set of ER⁺ breast tumor samples, collected before (n = 58) and after (n = 60) neoadjuvant treatment with the aromatase inhibitor letrozole, to prioritize genes as targets for combination therapy with letrozole treatment. We validate letrozole-induced tumor adaptation through coexpression and pathway analyses in an independent data set (n = 18).

Results

We find pervasive differential coexpression between the untreated and letrozole-treated tumor samples as evidence of letrozole-induced tumor adaptation. Based on patterns of coexpression, we identify ten genes as potential candidates for combination therapy with letrozole including EPCAM, a letrozole-induced essential gene and a target to which drugs have already been developed as cancer therapeutics. Through replication, we validate six letrozole-induced coexpression relationships and confirm the epithelial-to-mesenchymal transition as a process that is upregulated in the residual tumor samples following letrozole treatment.

Conclusions

To derive the greatest benefit from molecularly targeted drugs it is critical to design combination treatment strategies rationally. Incorporating knowledge of the tumor adaptation process into the design provides an opportunity to match targeted drugs to the evolving tumor phenotype and surmount resistance.

Follistatin-like protein 1 is a critical mediator of experimental Lyme arthritis and the humoral response to Borrelia burgdorferi infection

Follistatin-like protein 1 (FSTL-1) has recently been described as a critical mediator of CIA and a marker of disease activity. Lyme arthritis, caused by Borrelia burgdorferi, shares similarities with autoimmune arthritis and the experimental murine model collagen-induced arthritis (CIA). Because FSTL-1 is important in CIA and autoimmune arthritides, and Lyme arthritis shares similarities with CIA, we hypothesized that FSTL-1 may be an important mediator of Lyme arthritis. We demonstrate for the first time that FSTL-1 is induced by B. burgdorferi infection and is required for the development of Lyme arthritis in a murine model, utilizing a gene insertion to generate FSTL-1 hypomorphic mice. Using qPCR and qRT-PCR, we found that despite similar early infectious burden, FSTL-1 hypomorphic mice have improved spirochetal clearance in the face of attenuated arthritis and inflammatory cytokine production. Further, FSTL-1 mediates pathogen-specific antibody production and antigen recognition when assessed by ELISA and one- and two-dimensional immunoblotting. This study is the first to describe a role for FSTL-1 in the development of Lyme arthritis and anti-Borrelia response, and the first to demonstrate a role for FSTL-1 in response to infection, highlighting the potential for FSTL-1 as a target in the treatment of B. burgdorferi infection.

The CO-Regulation Database (CORD): a tool to identify coordinately expressed genes

Background

Meta-analysis of gene expression array databases has the potential to reveal information about gene function. The identification of gene-gene interactions may be inferred from gene expression information but such meta-analysis is often limited to a single microarray platform. To address this limitation, we developed a gene-centered approach to analyze differential expression across thousands of gene expression experiments and created the CO-Regulation Database (CORD) to determine which genes are correlated with a queried gene.

Results

Using the GEO and ArrayExpress database, we analyzed over 120,000 group by group experiments from gene microarrays to determine the correlating genes for over 30,000 different genes or hypothesized genes. CORD output data is presented for sample queries with focus on genes with well-known interaction networks including p16 (CDKN2A), vimentin (VIM), MyoD (MYOD1). CDKN2A, VIM, and MYOD1 all displayed gene correlations consistent with known interacting genes.

Conclusions

We developed a facile, web-enabled program to determine gene-gene correlations across different gene expression microarray platforms. Using well-characterized genes, we illustrate how CORD's identification of co-expressed genes contributes to a better understanding a gene's potential function. The website is found at http://cord-db.org.

Fstl1 antagonizes BMP signaling and regulates ureter development

Bone morphogenetic protein (BMP) signaling pathway plays important roles in urinary tract development although the detailed regulation of its activity in this process remains unclear. Here we report that follistatin-like 1 (Fstl1), encoding a secreted extracellular glycoprotein, is expressed in developing ureter and antagonizes BMP signaling activity. Mouse embryos carrying disrupted Fstl1 gene displayed prominent hydroureter arising from proximal segment and ureterovesical junction defects. These defects were associated with significant reduction in ureteric epithelial cell proliferation at E15.5 and E16.5 as well as absence of subepithelial ureteral mesenchymal cells in the urinary tract at E16.5 and E18.5. At the molecular level, increased BMP signaling was found in Fstl1 deficient ureters, indicated by elevated pSmad1/5/8 activity. In vitro study also indicated that Fstl1 can directly bind to ALK6 which is specifically expressed in ureteric epithelial cells in developing ureter. Furthermore, Sonic hedgehog (SHH) signaling, which is crucial for differentiation of ureteral subepithelial cell proliferation, was also impaired in Fstl1(-/-) ureter. Altogether, our data suggest that Fstl1 is essential in maintaining normal ureter development by antagonizing BMP signaling.

Reproductive consequences of developmental phytoestrogen exposure

Phytoestrogens, estrogenic compounds derived from plants, are ubiquitous in human and animal diets. These chemicals are generally much less potent than estradiol but act via similar mechanisms. The most common source of phytoestrogen exposure to humans is soybean-derived foods that are rich in the isoflavones genistein and daidzein. These isoflavones are also found at relatively high levels in soy-based infant formulas. Phytoestrogens have been promoted as healthy alternatives to synthetic estrogens and are found in many dietary supplements. The aim of this review is to examine the evidence that phytoestrogen exposure, particularly in the developmentally sensitive periods of life, has consequences for future reproductive health.

Follistatin-like 1 (Fstl1) is a bone morphogenetic protein (BMP) 4 signaling antagonist in controlling mouse lung development

Lung morphogenesis is a well orchestrated, tightly regulated process through several molecular pathways, including TGF-β/bone morphogenetic protein (BMP) signaling. Alteration of these signaling pathways leads to lung malformation. We investigated the role of Follistatin-like 1 (Fstl1), a secreted follistatin-module-containing glycoprotein, in lung development. Deletion of Fstl1 in mice led to postnatal lethality as a result of respiratory failure. Analysis of the mutant phenotype showed that Fstl1 is essential for tracheal cartilage formation and alveolar maturation. Deletion of the Fstl1 gene resulted in malformed tracheal rings manifested as discontinued rings and reduced ring number. Fstl1-deficient mice displayed septal hypercellularity and end-expiratory atelectasis, which were associated with impaired differentiation of distal alveolar epithelial cells and insufficient production of mature surfactant proteins. Mechanistically, Fstl1 interacted directly with BMP4, negatively regulated BMP4/Smad1/5/8 signaling, and inhibited BMP4-induced surfactant gene expression. Reducing BMP signaling activity by Noggin rescued pulmonary atelectasis of Fstl1-deficient mice. Therefore, we provide in vivo and in vitro evidence to demonstrate that Fstl1 modulates lung development and alveolar maturation, in part, through BMP4 signaling.

Establishment of clonal cell lines of taste buds from a p53(-/-) mouse tongue

A taste bud is a sensory organ and consists of 50-100 spindle-shaped cells. The cells function as taste acceptors. They have characteristics of both epithelial and neuronal cells. A taste bud contains four types of cells, type I, type II, type III cells, and basal cells. Taste buds were isolated from a tongue of a p53-deficient mouse at day 12, and 11 clonal taste bud (TBD) cell lines were established. In immunochemical analysis, all cell lines expressed cytokeratin 18, gustducin, T1R3, and neural cellular adhesion molecule, but not GLAST. In RT-PCR analysis, shh was not expressed in any of the cell lines. Further analysis with RT-PCR was conducted on four cell lines. They expressed G protein-coupled taste receptors; T1R3, T2R8 for sweet, bitter, umami. And they also expressed α-ENaC for salty taste. While, a candidate for sour receptor HCN4 was expressed in TBD-a1 and TBD-a7 lines. And another candidate for sour receptor PKD1L3 was slightly expressed in TBD-a1 and TBD-c1.

Profiling signatures of ovarian cancer tumour suppression using 2D-DIGE and 2D-LC-MS/MS with tandem mass tagging

Epithelial ovarian cancer (EOC) is the most common form of gynaecological malignancy in the developed world and has a poor prognosis due to its late detection. Identifying molecular markers of the disease may provide novel approaches to screening and could enable targeted treatment and the design of novel therapies. Although blood is recognized as a highly important source of disease-related biomarkers, the complexity and dynamic range of protein abundance in body fluids has hampered proteomic biomarker discovery and alternative approaches using cell models may be more successful. Herein, we have utilized two cellular models of EOC, where transfer of normal chromosome 18 material into the EOC cell lines TOV-112D and TOV-21G induced in vitro and in vivo suppression of their tumourigenic phenotype. A combination of quantitative two-dimensional difference gel electrophoresis (2D-DIGE) and two-dimensional-liquid chromatography tandem mass spectrometry (2D-LC-MS/MS) with tandem mass tagging (TMT) was employed to examine the whole cell, secreted and crude membrane proteomes of the parental and hybrid cell models to identify differentially expressed proteins as potential markers of tumour suppression. Protein changes of interest were confirmed by immunoblotting in additional hybrid and revertant cell lines where incorporated chromosome 18 material was lost. One candidate marker was also tested in sera from a set of ovarian cancer cases and controls. We have identified a list of promising candidate biomarkers for further testing and functional characterization.