FRAS1-related Extracellular Matrix Research Articles

Proteomic characteristics of the aqueous humor in Uyghur patients with pseudoexfoliation syndrome and pseudoexfoliative glaucoma

Pseudoexfoliation syndrome (PEX) is characterized by the deposition of fibrous pseudoexfoliation material (PEXM) in the eye, and secondary glaucoma associated with this syndrome has a faster and more severe clinical course. The incidence of PEX and pseudoexfoliative glaucoma (PEXG) exhibits ethnic clustering; however, few proteomic studies related to PEX and PEXG have been conducted in Asian populations. Therefore, we aimed to conduct proteomic analysis on the aqueous humor (AH) obtained from Uyghur patients with cataracts, those with PEX and cataracts, and those with PEXG and cataracts to better understand the molecular mechanisms of the disease and identify its potential biomarkers. To this end, AH was collected from patients with cataracts (n = 10, control group), PEX with cataracts (n = 10, PEX group), and PEXG with cataracts (n = 10, PEXG group) during phacoemulsification. Label-free quantitative proteomic techniques combined with bioinformatics were used to identify and analyze differentially expressed proteins (DEPs) in the AH of PEX and PEXG groups. Then, independent AH samples (n = 12, each group) were collected to validate DEPs by enzyme-linked immunosorbent assay (ELISA). The PEX group exhibited 25 DEPs, while the PEXG group showed 44 DEPs, both compared to the control group. Subsequently, we found three newly identified proteins in both PEX and PEXG groups, wherein FRAS1-related extracellular matrix protein 2 (FREM2) and osteoclast-associated receptor (OSCAR) exhibited downregulation, whereas coagulation Factor IX (F9) displayed upregulation. Bioinformatics analysis suggested that extracellular matrix interactions, abnormal blood-derived proteins, and lysosomes were mainly involved in the process of PEX and PEXG, and the PPI network further revealed F9 may serve as a potential biomarker for both PEX and PEXG. In conclusion, this study provides new information for understanding the proteomics of AH in PEX and PEXG.

Elevated Fras1-related extracellular matrix 3 in isocitrate dehydrogenase 1-mutant astrocytoma World Health Organization grade 4 predicts favorable prognosis in glioma: A bioinformatic and experimental analysis

Background and Aim: World Health Organization (WHO) grade 4 glioma is a malignancy of the central nervous system characterized by refractoriness to treatment and a high mortality rate. Isocitrate dehydrogenase (IDH) mutation is a crucial molecular event for the classification of glioma and associated with prognosis and exploring genetic and molecular differences between IDH mutant and wildtype glioma is crucial. The aim of this study was to investigate the prognostic gene between IDH mutant and wildtype WHO grade 4 glioma and its functional significance. Materials and Methods: The mRNA expression profile data of WHO grade 4 glioma were downloaded from the Gene Expression Omnibus and Chinese Glioma Genome Atlas databases. Bioinformatic analysis was performed to identify the differentially expressed genes between IDH1-mutant and wildtype WHO grade 4 glioma. Survival analysis, functional enrichment analysis, immune cell infiltration evaluation, and in vitro experimental validation were conducted to evaluate the prognostic and functional significance of Fras1-related extracellular matrix 3 (FREM3). This study was approved by the Institutional Ethics Committee of Xinqiao Hospital, Third Military Medical University (approval No. 2021-Y068-01). Results: Elevated expression of FREM3 in IDH1-mutant WHO grade 4 astrocytoma predicted favorable prognosis in glioma. FREM3 was negatively associated with epithelial–mesenchymal transition (EMT), angiogenesis, and hypoxia; notably, low expression of FREM3 was associated with a higher degree of immune cell infiltration. In vitro experiments demonstrated that high FREM3 expression might attenuate the process of EMT and cellular proliferation in glioma. Conclusions: The gene FREM3 plays a major role in IDH1-mutant WHO grade 4 glioma and elevated FREM3 predicts a favorable prognosis of glioma. Further investigation on FREM3 is warranted to elucidate the mechanisms underlying the malignant evolution of glioma.

Comprehensive analysis of FRAS1/FREM family as potential biomarkers and therapeutic targets in renal clear cell carcinoma.

Background: FRAS1 (Fraser syndrome protein 1), together with FREM1 (the Fras1-related extracellular matrix proteins 1) and FREM2, belonging to the FRAS1/FREM extracellular matrix protein family, are considered to play essential roles in renal organogenesis and cancer progression. However, their roles in kidney renal clear cell carcinoma (KIRC) remain to be elucidated. Methods: FRAS1/FREM RNA expression analysis was performed using TCGA/GTEx databases, and valided using GEO databases and real-time PCR. Protein expression was peformed using CPTAC databases. Herein, we employed an array of bioinformatics methods and online databases to explore the potential oncogenic roles of FRAS1/FREM in KIRC. Results: We found that FRAS1, FREM1 and FREM2 genes and proteins expression levels were significantly decreased in KIRC tissues than in normal tissues. Decreased FRAS1/FREM expression levels were significantly associated with advanced clinicopathological parameters (pathological stage, grade and tumor metastasis status). Notably, the patients with decreased FRAS1/FREM2 expression showed a high propensity for metastasis and poor prognosis. FRAS1/FREM were correlated with various immune infiltrating cells, especially CD4+ T cells and its corresponding subsets (Th1, Th2, Tfh and Tregs). FRAS1 and FREM2 had association with DNA methylation and their single CpG methylation levels were associated with prognosis. Moreover, FRAS1/FREM might exert antitumor effects by functioning in key oncogenic signalling pathways and metabolic pathways. Drug sensitivity analysis indicated that high FRAS1 and FREM2 expression can be a reliable predictor of targeted therapeutic drug response, highlighting the potential as anticancer drug targets. Conclusion: Together, our results indicated that FRAS1/FREM family members could be potential therapeutic targets and valuable prognostic biomarkers of KIRC.

Integrated Bioinformatics Identifies FREM1 as a Diagnostic Gene Signature for Heart Failure.

Objective This study is aimed at integrating bioinformatics and machine learning to determine novel diagnostic gene signals in the progression of heart failure disease. Methods The heart failure microarray datasets and RNA-seq datasets have been downloaded from the public database. Differentially expressed genes (DE genes) are screened out, and then, we analyze their biological functions and pathways. Integrating three machine learning methods, the least absolute shrinkage and selection operator (LASSO) algorithm, random forest (RF) algorithm, and support vector machine recursive feature elimination (SVM-RFE) are used to determine candidate diagnostic gene signals. Then, external independent RNA-seq datasets evaluate the diagnostic value of gene signals. Finally, the convolution tool CIBERSORT estimated the composition pattern of immune cell subtypes in heart failure and carried out a correlation analysis combined with gene signals. Results Under the set threshold, we obtained 47 DE genes with the most significant differences. Enrichment analysis shows that most of them are related to hypertrophy, matrix structural constituent, protein binding, inflammatory immune pathway, cardiovascular disease, and inflammatory disease. Three machine learning methods assisted in determining the potential characteristic signals Fras1-related extracellular matrix 1 (FREM1) and meiosis-specific nuclear structural 1 (MNS1). Validation of external datasets confirms that FREM1 is a diagnostic gene signal for heart failure. Immune cell subtypes of tissue specimens found T cell CD8, mast cell resting, T cell CD4 memory resting, T cell regulation (Tregs), monocytes, macrophages M2, T cell CD4 naive, macrophages M0, and neutrophils are associated with HF. Conclusion The gene signal FREM1 may be a potential molecular target in the development of HF and is related to the difference in immune infiltration of HF tissue.

Association of a Novel DOCK2 Mutation-Related Gene Signature With Immune in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a malignant tumor with high morbidity and mortality worldwide. Many studies have shown that dedicator of cytokinesis 2 (DOCK2) has a crucial role as a prognostic factor in various cancers. However, the potentiality of DOCK2 in the diagnosis of HCC has not been fully elucidated. In this work, we aimed to investigate the prognostic role of DOCK2 mutation in HCC. The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC) cohorts were utilized to identify the mutation frequency of DOCK2. Then, univariate Cox proportional hazard regression analysis, random forest (RF), and multivariate Cox regression analysis were performed to develop the risk score that was significantly related to DOCK2 mutation. Moreover, Gene Set Enrichment Analysis (GSEA), Gene Set Variation Analysis (GSVA), and immune correlation analysis were conducted for an in-depth study of the biological process of DOCK2 mutation involved in HCC. The results revealed that the mutation frequency of DOCK2 was relatively higher than that in non-cancer control subjects, and patients with DOCK2 mutations had a low survival rate and a poor prognosis compared with the DOCK2-wild group. In addition, the secretin receptor (SCTR), tetratricopeptide repeat, ankyrin repeat and coiled-coil domain-containing 1 (TANC1), Alkb homolog 7 (ALKBH7), FRAS1-related extracellular matrix 2 (FREM2), and G protein subunit gamma 4 (GNG4) were found to be the most relevant prognostic genes of DOCK2 mutation, and the risk score based on the five genes played an excellent role in predicting the status of survival, tumor mutation burden (TMB), and microsatellite instability (MSI) in DOCK2 mutant patients. In addition, DOCK2 mutation and the risk score were closely related to immune responses. In conclusion, the present study identifies a novel prognostic signature in light of DOCK2 mutation-related genes that shows great prognostic value in HCC patients; and this gene mutation might promote tumor progression by influencing immune responses. These data may provide valuable insights for future investigations into personalized forecasting methods and also shed light on stratified precision oncology treatment.

Shared and Tissue-Specific Genetic Features of Primary Myelofibrosis, Hepatic Fibrosis, Idiopathic Pulmonary Fibrosis and Kidney Fibrosis

Fibrosis is the hallmark of primary myelofibrosis (PMF) and contributes to organ failure of other tissues, including liver, kidney, heart, lung and skin. Hence, there is a need to identify shared mechanisms across fibrotic tissues to advance the development of anti-fibrotic therapies. We previously analyzed bone marrow from three patients with PMF using a transcriptomic profiling that quantified the expression of TGF-β signaling intermediates (1). This platform identified an abnormal expression signature that includes over-expression of genes downstream from the non-canonical ERK/p38 TGF-β signaling; for example, Jun, GADD45B, EVI1 and STAT1, reinforcing TGF-β as a novel therapeutic target for this disease.The aim of this study is to further clarify the role of TGF-β signaling in bone marrow from PMF, and to define common features of fibrosis in PMF, liver and lung. To achieve this aim, gene expression profiles in bone marrow from three additional PMF patients were compared to five non-diseased volunteers using the Illumina microarray Human HT-12_v4 Bead Chip gene expression array. These results were then compared to gene expression signatures from fibrotic tissues or cells including: activated hepatic stellate cells [100 upregulated and 100 downregulated (2); 100 upregulated (3)] and tissues from patients with idiopathic pulmonary fibrosis (100 upregulated and 100 downregulated, GSE47460) (4).The expression profiles of the three PMF patients were more heterogeneous, owing to their different disease phenotypes (International Prognostic Score System int-1-2 and fibrosis grade 1-3), while the controls were more tightly clustered. There were 750-1105 transcripts up- or down-regulated, respectively, in the three PMF samples relative to controls. Of those, 81 and 77 were consistently up- and down-regulated in all the patients. This common signature was interrogated by pathway analysis (Fig. 1). GO biological processes enrichment identified pathways controlling cytokine production and signaling, inflammatory responses, wound healing, chemotaxis and leukocyte migration as the most enriched terms. Among transcription factors analyzed by ENCODE, STAT5A was the most enriched transcription factor; however, STAT1 and 2, JUND and FOS were also ranked highly. The enriched differentially expressed KEGG pathways included a hematopoietic stem cell lineage, toll-like receptor, and NF-kappa-B signaling. Analyses of the data using gene set enrichment analysis (GSEA) of the hallmark gene sets identified heme metabolism as the most enriched pathway (NES=2.52, p=0.000), followed by interferon (NES 2.12-2.11, p=0.000), NF-kB (NES=2.09, p=0.000) and TP53 (NES=1.51, p=0.000) signaling. In addition, we identified positive enrichment of genes with binding motifs in regions spanning up to 4 kb around the transcriptional start site for AP-1, a component of transcriptional complexes formed by Fos and Jun (TRANSFAC database ver.7.4; http://gene-regulation.com/pub/databases.html) (NES=1.71-1.23, p=0.000-0.060).The PMF signature was compared to signatures from other fibrotic tissues: the two liver fibrosis signatures and the lung fibrosis signature, displayed modest similarity. Some common genes included activation of integrin-α9 (ITGA9) and thropomyosin α-1 (9 TPM1) when compared with liver fibrosis signatures, and ectoderm-neural cortex protein 1 (ENC1) and FRAS1-related extracellular matrix protein 1 (FREM1) when compared to the lung fibrosis signature.In summary, this study has reinforced the presence of a prominent TGF-β signature in the bone marrow of PMF, establishing this pathway as a potential therapeutic target, and identifying interferon and NF-kB signaling as additional pathways that are modulated in PMF. The analysis has also uncovered few potential fibrosis targets, e.g., ITGA9, TPMQ, ENC1 and FREM1, shared with other fibrotic tissues.

Facial cleft? The first case of manitoba\u2010oculo\u2010tricho\u2010anal syndrome with novel mutations in China: a case report

BackgroundManitoba-oculo-tricho-anal (MOTA) syndrome is a rare syndrome with only 27 cases reported worldwide so far, but none was reported in the population of Eastern Asia. Such extremely low prevalence might be contributed by misdiagnosis due to its similarities in ocular manifestations with facial cleft. In our study, we discovered the first case of MOTA syndrome in the population of China, with 2 novel FRAS1 related extracellular matrix 1 (FREM1) gene stop-gain mutations confirmed by whole exome sequencing.Case presentationA 12-year-old Chinese girl presented with facial cleft-like deformities including aberrant hairline, blepharon-coloboma and broad bifid nose since birth. Whole exome sequencing resulted in the identification of 2 novel stop-gain mutations in the FREM1 gene. Diagnosis of MOTA syndrome was then established.ConclusionsWe discovered the first sporadic case of MOTA syndrome according to clinical manifestations and genetic etiology in the Chinese population. We have identified 2 novel stop-gain mutations in FREM1 gene which further expands the spectrum of mutational seen in the MOTA syndrome. Further research should be conducted for better understanding of its mechanism, establishment of an accurate diagnosis, and eventually the exploitation of a more effective and comprehensive therapeutic intervention for MOTA syndrome.

Elevated expression of FREM1 in breast cancer indicates favorable prognosis and high‐level immune infiltration status

Breast cancer (BC) poses one of the major threats to female's health worldwide. Immune infiltration in BC is a key representative of the tumor microenvironment and has been proven highly relevant for prognosis. The role of the FREM1 (FRAS1‐Related Extracellular Matrix 1) gene in carcinoma has not studied, moreover, the underlying mechanism remains largely unknown. This study aims to investigate the expression profile and potential action of FREM1 on BC progression. We applied series of bioinformatic methods as well as immunohistochemistry (IHC) and immunofluorescence (IF) to analyze FREM1 expression profile, its relationship with clinicopathological characteristics, impact on clinical outcomes, relevant functions, correlation with immune infiltration in BC. The results demonstrated that FREM1 had a dramatically reduced expression in BC tissues, possessed an inverse correlation with stage, age, and metastasis, and exhibited a higher level in invasive lobular breast carcinoma than in ductal one. Furthermore, decreased FREM1 expression was often associated with estrogen receptor (ER)/progesterone receptor (PR) negative and triple negative breast carcinoma (TNBC) status while human epidermal growth factor 2 (Her‐2) positive status, and considerably correlated with a worse overall survival (OS) and recurrence‐free survival (RFS). Meanwhile, the univariate/multivariate Cox model revealed that low‐FREM1 expression can be an independent prognostic factor for BC. Additionally, FREM1 was mainly involved in the cell metabolism and immune cells infiltration. Moreover, IHC and IF demonstrated a positive correlation of its expression with the immune infiltrating levels of CD4+, CD8+ T cells, and CD86+ M1 macrophages while a negative correlation with CD68+ pan‐macrophages and CD163+ M2 macrophages. These findings suggest that FREM1 can be a potential biomarker for evaluating the immune infiltrating status, and the BC prognosis.

Heterozygous intragenic deletions of FREM1 are not associated with trigonocephaly.

Recessive mutations in FRAS1-related extracellular matrix 1 (FREM1) are associated with two rare genetic disorders, Manitoba-oculo-tricho-anal (MOTA) and bifid nose with or without anorectal and renal anomalies (BNAR). Fraser syndrome is a more severe disorder that shows phenotypic overlap with both MOTA and anorectal and renal anomalies and results from mutations in FRAS1, FREM2 and GRIP1. Heterozygous missense mutations in FREM1 were reported in association with isolated trigonocephaly with dominant inheritance and incomplete penetrance. Moreover, large deletions encompassing FREM1 have been reported in association with a syndromic form of trigonocephaly and were designated as trigonocephaly type 2. Trigonocephaly results from premature closure of the metopic suture and typically manifests as a form of nonsyndromic craniosynostosis. We report on 20 patients evaluated for developmental delay and without abnormal metopic suture. Chromosomal microarray analysis revealed heterozygous FREM1 deletions in 18 patients and in 4 phenotypically normal parents. Two patients were diagnosed with MOTA and had homozygous FREM1 deletions. Therefore, although our results are consistent with the previous reports of homozygous deletions causing MOTA, we report no association between heterozygous FREM1 deletions and trigonocephaly in this cohort.

Deficiency of FRAS1-related extracellular matrix 1 (FREM1) causes congenital diaphragmatic hernia in humans and mice.

Deficiency of FRAS1-related extracellular matrix 1 (FREM1) causes congenital diaphragmatic hernia in humans and mice.

Shared and Tissue-Specific Expression Signatures between Bone Marrow from Primary Myelofibrosis and Essential Thrombocythemia

Megakaryocytes have been implicated in the micro-environmental abnormalities associated with fibrosis and hematopoietic failure in the bone marrow (BM) of primary myelofibrosis (PMF) patients, the Philadelphia-negative myeloproliferative neoplasm (MPN) associated with the poorest prognosis. To identify possible therapeutic targets for restoring BM functions in PMF, we compared the expression profiling of PMF BM with that of BM from essential thrombocytopenia (ET), a fibrosis-free MPN also associated with BM megakaryocyte hyperplasia. The signature of PMF BM was also compared with published signatures associated with liver and lung fibrosis. Gene set enrichment analysis (GSEA) identified distinctive differences between the expression profiles of PMF and ET. Notch, K-Ras, IL-8, and apoptosis pathways were altered the most in PMF as compared with controls. By contrast, cholesterol homeostasis, unfolded protein response, and hypoxia were the pathways found altered to the greatest degree in ET compared with control specimens. BM from PMF expressed a noncanonical transforming growth factor β (TGF-β) signature, which included activation of ID1, JUN, GADD45b, and genes with binding motifs for the JUN transcriptional complex AP1. By contrast, the expression of ID1 and GADD45b was not altered and there was a modest signal for JUN activation in ET. The similarities among PMF, liver fibrosis, and lung fibrosis were modest and included activation of integrin-α9 and tropomyosin-α1 between PMF and liver fibrosis, and of ectoderm-neural cortex protein 1 and FRAS1-related extracellular matrix protein 1 between PMF and lung fibrosis, but not TGF-β. These data identify TGF-β as a potential target for micro-environmental therapy in PMF.

Loss-of-function mutations in FREM2 disrupt eye morphogenesis

Cryptophthalmos is a rare congenital disorder characterized by ocular dysplasia with eyelid malformation. Complete cryptophthalmos is characterized by the presence of continuous skin from the forehead over the eyes and onto the cheek, along with complete fusion of the eyelids. In the present study, we characterized the clinical manifestations of three patients with isolated bilateral cryptophthalmos. These patients shared the same c.6499C > T missense mutation in the FRAS1-related extracellular matrix protein 2 (FREM2) gene, while each individual presented an additional nonsense mutation in the same gene (Patient #1, c.2206C > T; Patient #2, c.5309G > A; and Patient #3, c.4063C > T). Then, we used CRISPR/Cas9 to generate mice carrying Frem2R725X/R2156W compound heterozygous mutations, and showed that these mice recapitulated the human isolated cryptophthalmos phenotype. We detected FREM2 expression in the outer plexiform layer of the retina for the first time in the cryptophthalmic eyes, and the levels were comparable to the wild-type mice. Moreover, a set of different expressed genes that may contribute secondarily to the phenotypes were identified by performing RNA sequencing (RNA-seq) of the fetal Frem2 mutant mice. Our findings extend the spectrum of FREM2 mutations, and provide insights into opportunities for the prenatal diagnosis of isolated cryptophthalmos. Furthermore, our work highlights the importance of the FREM2 protein during the development of eyelids and the anterior segment of the eyeballs, establishes a suitable animal model for studying epithelial reopening during eyelid development and serves as a valuable reference for further mechanistic studies of the pathogenesis of isolated cryptophthalmos.

A homozygous mutation p.Arg2167Trp in FREM2 causes isolated cryptophthalmos.

Cryptophthalmos (CO, MIM: 123570) is rare congenital anomalies of eyelid formation, which can occur alone or in combination with multiple congenital anomalies as part of Fraser syndrome (FS) or Manitoba Oculotrichoanal syndrome. Causal mutations have been identified for these syndromes but not in the isolated cases. Here, we described two patients from two unrelated Chinese families: one with unilateral isolated CO, while the other with unilateral CO and renal agenesis. A novel homozygous mutation (c.6499C>T: p.Arg2167Trp) and compound heterozygote mutations (c.15delG; c.6499C>T: p.Arg2167Trp) in FREM2 (NM_172862) were identified for the two patients, respectively. The deletion mutation c.15delG resulted in a frameshift and triggered the nonsense-mediated mRNA decay. For the shared missense mutation, p.Arg2167Trp altered a conserved residue and was predicted to affect protein structure by in silico analysis. Functional analysis revealed that Arg2167Trp mutant decreased its interaction with FRAS1 related extracellular matrix 1 (FREM1) and impaired the function of the FRAS1-FRAS1 related extracellular matrix 1 (FREM2)-FREM1 ternary complex required for normal embryogenesis. Furthermore, considering that mutation (c.5914C>T: p.Glu1972Lys) in FREM2 causes FS, a severe systemic disorder, we also compared these two different missense mutations. Our results showed that p.Arg2167Trp had a weaker effect in interrupting interactions between FREM2 and FREM1 than FS-associated missense mutation p.Glu1972Lys. Overall, our data demonstrate that the homozygous mutation p.Arg2167Trp in FREM2 causes isolated CO, which will facilitate our better understanding of the molecular mechanisms underlying the disease.

Mesenchymal expression of the FRAS1/FREM2 gene unit is decreased in the developing fetal diaphragm of nitrofen-induced congenital diaphragmatic hernia.

Developmental mutations that inhibit normal formation of extracellular matrix (ECM) in fetal diaphragms have been identified in congenital diaphragmatic hernia (CDH). FRAS1 and FRAS1-related extracellular matrix 2 (FREM2), which encode important ECM proteins, are secreted by mesenchymal cells during diaphragmatic development. The FRAS1/FREM2 gene unit has been shown to form a ternary complex with FREM1, which plays a crucial role during formation of human and rodent diaphragms. Furthermore, it has been demonstrated that the diaphragmatic expression of FREM1 is decreased in the nitrofen-induced CDH model. We hypothesized that FRAS1 and FREM2 expression is decreased in the developing diaphragms of fetal rats with nitrofen-induced CDH. Pregnant rats were exposed to either nitrofen or vehicle on gestational day 9 (D9), and fetuses were harvested on D13, D15 and D18. Microdissected diaphragms were divided into nitrofen-exposed/CDH and control samples (n=12 per time-point and experimental group, respectively). Diaphragmatic gene expression levels of FRAS1 and FREM2 were analyzed by qRT-PCR. Immunofluorescence double staining for FRAS1 and FREM2 was combined with the mesenchymal marker GATA4 in order to evaluate protein expression and localization in pleuroperitoneal folds (PPFs) and fetal diaphragmatic tissue. Relative mRNA expression of FRAS1 and FREM2 were significantly reduced in PPFs of nitrofen-exposed fetuses on D13 (1.76±0.86 vs. 3.09±1.15; p<0.05 and 0.47±0.26 vs. 0.82±0.36; p<0.05), developing diaphragms of nitrofen-exposed fetuses on D15 (1.45±0.80 vs. 2.63±0.84; p<0.05 and 0.41±0.16 vs. 1.02±0.49; p<0.05) and fully muscularized diaphragms of CDH fetuses on D18 (1.35±0.75 vs. 2.32±0.92; p<0.05 and 0.37±0.24 vs. 0.70±0.32; p<0.05) compared to controls. Confocal laser scanning microscopy revealed markedly diminished FRAS1 and FREM2 immunofluorescence in diaphragmatic mesenchyme, which was associated with reduced proliferation of mesenchymal cells in nitrofen-exposed PPFs and fetal CDH diaphragms on D13, D15 and D18 compared to controls. Decreased mesenchymal expression of FRAS1 and FREM2 in the nitrofen-induced CDH model may cause failure of the FRAS1/FREM2 gene unit to activate FREM1 signaling, disturbing the formation of diaphragmatic ECM and thus contributing to the development of diaphragmatic defects in CDH.

Gene Expression of FRAS1-Related Extracellular Matrix 1 Is Decreased in Nitrofen-Induced Congenital Diaphragmatic Hernia.

The origin of congenital diaphragmatic hernia (CDH) is considered to lie in a malformation of the nonmuscular primordial diaphragm. It is known that fetal diaphragmatic development requires the structural integrity of its underlying mesenchymal tissue. Developmental mutations that inhibit the formation of normal diaphragmatic mesenchyme have been shown to cause CDH. FRAS1-related extracellular matrix 1 (FREM1) plays a critical role in the development of the fetal diaphragm. It has been demonstrated that a deficiency of FREM1 can lead to CDH both in humans and mice. Furthermore, FREM1-deficient fetuses exhibit a decreased level of mesenchymal cell proliferation in their developing diaphragms. We hypothesized that FREM1 expression is decreased in developing diaphragms of fetal rats with nitrofen-induced CDH. Timed-pregnant rats were exposed to either nitrofen or vehicle on gestational day 9 (D9), and fetuses were harvested on selected time-points D13, D15, and D18. Dissected diaphragms (n = 72) were divided into control and nitrofen-exposed samples (n = 12 per time-point and experimental group). Diaphragmatic gene expression levels of FREM1 were analyzed by quantitative polymerase chain reaction. Immunofluorescence staining for FREM1 was combined with the mesenchymal marker GATA4 to localize FREM1 protein expression and tissue distribution in fetal diaphragms. In nitrofen-exposed fetuses, relative mRNA expression of FREM1 was significantly reduced in pleuroperitoneal folds on D13 (0.30 ± 0.23 vs. 0.83 ± 0.19; p < 0.05), developing diaphragms on D15 (0.54 ± 0.22 vs. 1.19 ± 0.28; p < .05) and fully muscularized diaphragms on D18 (0.49 ± 0.37 vs. 0.97 ± 0.53; p < 0.05) in comparison with controls. Confocal laser scanning microscopy revealed markedly diminished diaphragmatic FREM1 immunofluorescence, which was associated with reduced proliferation of diaphragmatic mesenchymal cells in nitrofen-exposed fetuses on D13, D15, and D18 compared to controls. Decreased expression of FREM1 in the nitrofen-induced CDH model may disturb the formation of the diaphragmatic mesenchyme, thus contributing to the development of diaphragmatic defects.

FRAS1-related extracellular matrix 3 (FREM3) single-nucleotide polymorphism effects on gene expression, amygdala reactivity and perceptual processing speed: An accelerated aging pathway of depression risk.

The A allele of the FRAS1-related extracellular matrix protein 3 (FREM3) rs7676614 single nucleotide polymorphism (SNP) was linked to major depressive disorder (MDD) in an early genome-wide association study (GWAS), and to symptoms of psychomotor retardation in a follow-up investigation. In line with significant overlap between age- and depression-related molecular pathways, parallel work has shown that FREM3 expression in postmortem human brain decreases with age. Here, we probe the effect of rs7676614 on amygdala reactivity and perceptual processing speed, both of which are altered in depression and aging. Amygdala reactivity was assessed using a face-matching BOLD fMRI paradigm in 365 Caucasian participants in the Duke Neurogenetics Study (DNS) (192 women, mean age 19.7 ± 1.2). Perceptual processing speed was indexed by reaction times in the same task and the Trail Making Test (TMT). The effect of rs7676614 on FREM3 mRNA brain expression levels was probed in a postmortem cohort of 169 Caucasian individuals (44 women, mean age 50.8 ± 14.9). The A allele of rs7676614 was associated with blunted amygdala reactivity to faces, slower reaction times in the face-matching condition (p < 0.04), as well as marginally slower performance on TMT Part B (p = 0.056). In the postmortem cohort, the T allele of rs6537170 (proxy for the rs7676614 A allele), was associated with trend-level reductions in gene expression in Brodmann areas 11 and 47 (p = 0.066), reminiscent of patterns characteristic of older age. The low-expressing allele of another FREM3 SNP (rs1391187) was similarly associated with reduced amygdala reactivity and slower TMT Part B speed, in addition to reduced BA47 activity and extraversion (p < 0.05). Together, these results suggest common genetic variation associated with reduced FREM3 expression may confer risk for a subtype of depression characterized by reduced reactivity to environmental stimuli and slower perceptual processing speed, possibly suggestive of accelerated aging.

Segmental and restricted localization pattern of Fras1 in the developing meningeal basement membrane in mouse

The Fras1/Frem family of extracellular matrix proteins consists of Fras1 and its structurally related proteins, Frem1 (Fras1-related extracellular matrix protein 1), Frem2 and Frem3. These are co-localized in embryonic epithelial basement membranes (BMs), where they contribute to epithelial-mesenchymal adhesion. Although Fras1 localization pattern in epithelial BMs has been well defined, it has not yet been comprehensively studied in the central nervous system. Here, we demonstrate the immunohistochemical profile of Fras1 in the developing mouse brain and reveal an exclusively meningeal BM protein deposition. Interestingly, Fras1 displays a segmental localization pattern, which is restricted to certain regions of the meningeal BM. Frem2 protein displays a similar localization pattern, while Frem3 is rather uniformly distributed throughout the meningeal BM. Fras1 and Frem2 proteins are detected in regions of the BM that underlie organizing centers, such as the roof plate (RP) of diencephalon, midbrain and hindbrain, and the RP-derived structures of telencephalon (choroid plexus and hem). Organizing centers exert their activity via the production of bioactive molecules, which are potential Fras1 ligands. The restricted pattern of Fras1 and Frem2 proteins indicates a molecular compartmentalization of the meningeal BM that could reflect, yet unspecified, functional and structural differences.

Novel frem1-related mouse phenotypes and evidence of genetic interactions with gata4 and slit3.

The FRAS1-related extracellular matrix 1 (FREM1) gene encodes an extracellular matrix protein that plays a critical role in the development of multiple organ systems. In humans, recessive mutations in FREM1 cause eye defects, congenital diaphragmatic hernia, renal anomalies and anorectal malformations including anteriorly placed anus. A similar constellation of findings–microphthalmia, cryptophthalmos, congenital diaphragmatic hernia, renal agenesis and rectal prolapse–have been described in FREM1-deficient mice. In this paper, we identify a homozygous Frem1 missense mutation (c.1687A>T, p.Ile563Phe) in an N-ethyl-N-nitrosourea (ENU)-derived mouse strain, crf11, with microphthalmia, cryptophthalmos, renal agenesis and rectal prolapse. This mutation affects a highly conserved residue in FREM1’s third CSPG domain. The p.Ile563Phe change is predicted to be deleterious and to cause decreased FREM1 protein stability. The crf11 allele also fails to complement the previously described eyes2 allele of Frem1 (p.Lys826*) providing further evidence that the crf11 phenotype is due to changes affecting Frem1 function. We then use mice bearing the crf11 and eyes2 alleles to identify lung lobulation defects and decreased anogenital distance in males as novel phenotypes associated with FREM1 deficiency in mice. Due to phenotypic overlaps between FREM1-deficient mice and mice that are deficient for the retinoic acid-responsive transcription factor GATA4 and the extracellular matrix protein SLIT3, we also perform experiments to look for in vivo genetic interactions between the genes that encode these proteins. These experiments reveal that Frem1 interacts genetically with Gata4 in the development of lung lobulation defects and with Slit3 in the development of renal agenesis. These results demonstrate that FREM1-deficient mice faithfully recapitulate many of the phenotypes seen in individuals with FREM1 deficiency and that variations in GATA4 and SLIT3 expression modulate some FREM1-related phenotypes in mice.

Deficiency of FRAS1-related extracellular matrix 1 (FREM1) causes congenital diaphragmatic hernia in humans and mice

Congenital diaphragmatic hernia (CDH) is a common life-threatening birth defect. Recessive mutations in the FRAS1-related extracellular matrix 1 (FREM1) gene have been shown to cause bifid nose with or without anorectal and renal anomalies (BNAR) syndrome and Manitoba oculotrichoanal (MOTA) syndrome, but have not been previously implicated in the development of CDH. We have identified a female child with an isolated left-sided posterolateral CDH covered by a membranous sac who had no features suggestive of BNAR or MOTA syndromes. This child carries a maternally-inherited ~86 kb FREM1 deletion that affects the expression of FREM1's full-length transcripts and a paternally-inherited splice site mutation that causes activation of a cryptic splice site, leading to a shift in the reading frame and premature termination of all forms of the FREM1 protein. This suggests that recessive FREM1 mutations can cause isolated CDH in humans. Further evidence for the role of FREM1 in the development of CDH comes from an N-ethyl-N-nitrosourea -derived mouse strain, eyes2, which has a homozygous truncating mutation in Frem1. Frem1(eyes2) mice have eye defects, renal agenesis and develop retrosternal diaphragmatic hernias which are covered by a membranous sac. We confirmed that Frem1 is expressed in the anterior portion of the developing diaphragm and found that Frem1(eyes2) embryos had decreased levels of cell proliferation in their developing diaphragms when compared to wild-type embryos. We conclude that FREM1 plays a critical role in the development of the diaphragm and that FREM1 deficiency can cause CDH in both humans and mice.

Abstract 799: Comprehensive proteomic analysis of cisplatin resistance in ovarian cancer

Abstract We have conducted a comprehensive proteomic analysis of an ovarian cancer cell line (A2780) and its cisplatin resistant daughter line (A2780-CP20) to identify key regulators and signaling pathways that confer cisplatin resistance. Quantitative proteomic profiling was conducted of defined biological compartments including that from global lysates, the nuclear fraction, the phosphoproteome and the secretome. Total cell lysates and nuclear fractions were harvested from A2780 and A2780-CP20 cultured in the presence or absence of cisplatin (3 µM) for 72 h. The secretome fractions were collected from A2780 and A2780-CP20 cultured in serum-free, phenol red-free media in the presence or absence of cisplatin (3 µM) for 24 h. Phosphopeptides were enriched from peptide digests of total lysates of A2780 and A2780-CP20 cultured in the presence or absence of cisplatin (3 µM) for 15 min using TiO2. Sample digests were analyzed by high-resolution LC-MS/MS that resulted in the identification of 2703, 2286, 1815, and 1362 proteins from the global, nuclear, secretome, and phosphoproteome fractions, respectively. Spectral counting was utilized to quantify the relative abundance of proteins identified. Nuclear proteins identified at elevated abundance in the cisplatin resistant A2780-CP20 including an array of chromatin remodeling proteins, such as SATB1, SATB2, coilin, AT-rich interactive domain-containing protein 3A (ARID3A), ARID3B, and ARID3Cwere validated by Western blot and qPCR in A2780/A2780-CP20 as well as other gynecologic cancer cell lines. Modulation of the abundance level of these candidates and the phenotypic impact on cisplatin resistance utilizing shRNA knockdown will be described. Differential proteins selected from the secretome analysis for western blot validation include Fras1-related extracellular matrix protein 2 (FREM2), stanniocalcin-1 (STC1), angio-associated migratory cell protein (AAMP), plasminogen activator inhibitor 1 (SERPINE1), high mobility group protein B1 (HMGB1), and chloride intracellular channel protein 2 (CLIC4), stromelysin-2 (MMP10), interstitial collagenase (MMP2), and CD166 antigen. Validated candidate protein targets from the secretome analysis will be tested by IHC on formalin fixed tissue sections as well as ELISA and multiple reaction monitoring (MRM) by mass spectrometry in serum from recurrent and non-recurrent ovarian cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 799. doi:1538-7445.AM2012-799