FHX.L and FHX.S, two isoforms of the human fork-head factor FHX (FOXJ2) with differential activity

Investigation of Rare Non-Coding Variants in Familial Multiple Myeloma

Multiple myeloma (MM) is a plasma cell malignancy whereby a single clone of plasma cells over-propagates in the bone marrow, resulting in the increased production of monoclonal immunoglobulin. While the complex genetic architecture of MM is well characterized, much less is known about germline variants predisposing to MM. Genome-wide sequencing approaches in MM families have started to identify rare high-penetrance coding risk alleles. In addition, genome-wide association studies have discovered several common low-penetrance risk alleles, which are mainly located in the non-coding genome. Here, we further explored the genetic basis in familial MM within the non-coding genome in whole-genome sequencing data. We prioritized and characterized 150 upstream, 5' untranslated region (UTR) and 3' UTR variants from 14 MM families, including 20 top-scoring variants. These variants confirmed previously implicated biological pathways in MM development. Most importantly, protein network and pathway enrichment analyses also identified 10 genes involved in mitogen-activated protein kinase (MAPK) signaling pathways, which have previously been established as important MM pathways.

miR-20a/Foxj2 Axis Mediates Growth and Metastasis of Colorectal Cancer Cells as Identified by Integrated Analysis

BACKGROUND MicroRNAs (miRNAs) have a significant regulatory effect on the proliferation, migration, and invasion of cells, and have been widely reported to have oncogenic or tumor-suppressive impacts on various tumors. In the present study we assessed the regulation and function of miR-20a on colorectal cancer (CRC) cell lines. MATERIAL AND METHODS qPCR was used to quantify miR-20a expression. Luciferase reporter assay was conducted to confirm Foxj2 3'UTR associations. In addition, the function of miR-20a and Foxj2 in CRC was detected using MTT, colony formation, transwell assays, and cell cycle analysis. RESULTS Our data revealed that miR-20a expression was elevated in the CRC cell lines, and cell migration, proliferation, and invasion abilities were promoted by the overexpression of miR-20a. Moreover, Foxj2 was authenticated as a direct target gene of miR-20a in CRC cells. Furthermore, we found that the ectopic Foxj2 dramatically suppressed miR-20a-promoted proliferation, migration, invasion, and xenografts in vitro and in vivo, and induced cell cycle arrest at G1 stage. CONCLUSIONS Our results showing the roles of miR-20a/Foxj2 in carcinogenesis of CRC may help improve treatment of CRC.

Foxj2 overexpression is associated with poor prognosis, progression, and metastasis in nasopharyngeal carcinoma

Foxj2, a novel member of Forkhead box family, has been reported to play an important role in tumorigenesis, progression, and metastasis of certain cancers. However, the expression status and effects of Foxj2 on nasopharyngeal carcinoma (NPC) progression and metastasis remain debated. In this study, we first examined the expression of Foxj2 in NPC by immunohistochemistry and Western blotting analysis. We confirmed significantly elevated expression of Foxj2 in NPC tissues and cell lines. Next, the relationships between Foxj2 expression levels and the clinicopathological factors were investigated. Its expression level correlated with T-classification (P=0.026), distant metastasis (P=0.004), and clinical stage (P=0.029). In addition, high expression of Foxj2 was associated with poor prognosis in NPC patients. The effects of Foxj2 on cell proliferation and migration were explored by RNA interference (RNAi) with CCK-8 assay, cell cycle analyses, wound healing, and transwell assay. In conclusion, our data indicate that Foxj2 upregulation promotes the progression and migration of NPC. It makes Foxj2 serve as a potential therapeutic target for the treatment of NPC.

Targeting STOX1 in the therapy of preeclampsia

INTRODUCTION

Preeclampsia is a major pregnancy disease, explained partly by genetic predispositions. STOX1, a transcription factor discovered in 2005, was the first gene directly associated with genetic forms of the disease. Alterations of STOX1 expression as well as STOX1 variants have also been associated to Alzheimer's disease. These observations make of this gene a putative therapeutic target. Area covered: Two major isoforms (STOX1A and STOX1B) are encoded by the gene and are theoretically able to compete for the same binding site, while only the most complete (STOX1A) is supposed to be able to activate gene expression. This makes the ratio between STOX1A and STOX1B as well as their position inside the cell (nucleus or cytoplasm) crucial to understand how STOX1 functions. STOX1 appears to have multiple gene targets, especially in pathways connected to inflammation, oxidative stress, and cell cycle. Expert opinion: STOX1-directed therapies, could be directed either towards its targets (genes or pathways), or directly at STOX1. For this the addressing of STOX1 to various cell compartments could theoretically be modified; also it could be possible of altering the balance between the two isoforms, through selectively inhibiting one of them, possibly improving the outcomes in severe preeclampsia.

The prognostic role and reduced expression of FOXJ2 in human hepatocellular carcinoma

The current study aimed to investigate the potential role of the FOXJ2 (forkhead box J2) protein in the pathology of hepatocellular carcinoma (HCC). Western blotting was performed to determine the expression levels of FOXJ2 in HCC tissues and HCC cells. Specimens from 110 patients with HCC undergoing hepatic resection were evaluated for FOXJ2 expression using an immunohistochemical assay. The correlation between FOXJ2 expression and clinicopathological factors of the patients was determined by statistical analysis to determine the prognostic merit of FOXJ2 expression in HCC. The detailed involvement of FOXJ2 in the regulation of HCC proliferation was further investigated using FOXJ2‑targeting small interfering RNA (siRNA). FOXJ2 protein was identified to be significantly downregulated in HCC tissues compared with adjacent normal liver tissues. Immunohistochemical analysis demonstrated that the expression of FOXJ2 was negatively correlated with Ki‑67 levels in HCC specimens (r=‑0.679, P<0.001). Furthermore, statistical analysis indicated FOXJ2 expression was significantly associated with histological differentiation (P=0.005), the size of largest tumor (P=0.002) and metastasis (P=0.036). Using Kaplan‑Meier analysis, it was demonstrated that high FOXJ2 expression levels predicted significantly improved patient survival rates compared with low FOXJ2 expression levels (P<0.001). In addition, it was observed that interference of FOXJ2 expression using siRNA oligos led to the promotion of proliferation of HepG2 cells. FOXJ2 was markedly downregulated in HCC tissues. The expression of FOXJ2 was correlated with tumor size, histological differentiation and metastasis. Low expression levels of FOXJ2 predicted poor prognosis for patients with HCC, suggesting that FOXJ2 may be a candidate prognostic marker of HCC. Depletion of FOXJ2 caused the promotion of HCC cell proliferation, implicating that FOXJ2 may serve an inhibitory role in the regulation of HCC cell proliferation.

Abnormal expression of Forkhead Box J2 (FOXJ2) suppresses migration and invasion in extrahepatic cholangiocarcinoma and is associated with prognosis

Extrahepatic cholangiocarcinoma (CC) is an aggressive malignancy with dismal prognosis and characterized by early invasion, metastasis and postoperative recurrence. Therefore, understanding the main molecular mechanisms of this malignancy is the key for the development of novel and effective therapeutic strategies for extrahepatic CC. Foxj2 is a novel forkhead factor. Several FOX family members have been reported to play an important role in tumorigenesis and the progression of certain cancers. In this study, real-time quantitative RT-PCR (qRT-PCR), western blotting, and immunohistochemical staining were used to examine FOXJ2 expression in extrahepatic CC tissues and adjacent normal bile duct tissues. The molecular mechanisms of FOXJ2 expression and its effects on cell proliferation, migration and invasion were also explored by MTT assay, wound healing assay and Transwell assay. The relationships between the FOXJ2 expression levels, the clinicopathological factors, and patient survival were investigated. FOXJ2 mRNA and protein levels were downregulated in extrahepatic CC tissues compared to adjacent normal bile duct tissues. In addition, decreased FOXJ2 was associated disease progression in extrahepatic CC samples. Overexpression FOXJ2 expression markedly inhibited cell proliferation, migration and invasion in vitro. FOXJ2 is a transcription factor that has been reported to induce epithelial-mesenchymal transition (EMT). These findings indicated that FOXJ2 gene played a tumor suppressor role in extrahepatic CC, which proposed this gene as a new therapeutic target for extrahepatic CC patients.

Foxj3 transcriptionally activates Mef2c and regulates adult skeletal muscle fiber type identity

The mechanisms that regulate skeletal muscle differentiation, fiber type diversity and muscle regeneration are incompletely defined. Forkhead transcription factors are critical regulators of cellular fate determination, proliferation, and differentiation. We identified a forkhead/winged helix transcription factor, Foxj3, which was expressed in embryonic and adult skeletal muscle. To define the functional role of Foxj3, we examined Foxj3 mutant mice. Foxj3 mutant mice are viable but have significantly fewer Type I slow-twitch myofibers and have impaired skeletal muscle contractile function compared to their wild type controls. In response to a severe injury, Foxj3 mutant mice have impaired muscle regeneration. Foxj3 mutant myogenic progenitor cells have perturbed cell cycle kinetics and decreased expression of Mef2c. Examination of the skeletal muscle 5' upstream enhancer of the Mef2c gene revealed an evolutionary conserved forkhead binding site (FBS). Transcriptional assays in C2C12 myoblasts revealed that Foxj3 transcriptionally activates the Mef2c gene in a dose dependent fashion and binds to the conserved FBS. Together, these studies support the hypothesis that Foxj3 is an important regulator of myofiber identity and muscle regeneration through the transcriptional activation of the Mef2c gene.

Biological effects of FoxJ2 over-expression

As reported previously, we have extensively studied FoxJ2, a member of the Fork Head transcription factors family. While the biochemical and functional structures of this transcription factor are well understood, its biological function remains unknown. Here, we present data that address this point using transgenic mouse technology. We found that the birth rate and the number of transgenic animals obtained when transferring embryos over-expressing the FoxJ2 protein were lower than those obtained with embryos over-expressing a control protein, suggesting FoxJ2 overexpression has a negative effect on embryonic development. Transient FoxJ2 transgenesis experiments have confirmed that FoxJ2 over-expression has a lethal effect on embryonic development from E10.5. Moreover, in vitro culture of FoxJ2-microinjected embryos demonstrated a significant developmental blockage, indicating that FoxJ2 could also have an effect on pre-implantation stages. Most probably, these negative effects of FoxJ2 over-expression during development also explain the low percentage of adult transgenic mice obtained. Furthermore, most of the transgenic mice that lived to adulthood did not show transgene expression. In fact, the only two adult transgenic animals (one male and one female) in which FoxJ2 transgene expression was detected showed a mosaic expression and died prematurely as a result of cardio-respiratory failure. Postmortem analysis of these animals revealed a hypertrophic heart and abnormal testes in the male. In order to identify genes regulated by FoxJ2 consistent with the phenotypes observed for FoxJ2 transgenic mice, EMSA assays and co-transfection experiments were carried out. Our data indicate that the genes coding for the gap junction protein Connexin-43 and the cell-cell contact protein E-Cadherin, may be good candidates for FoxJ2-regulated genes. Interestingly, Connexin-43 and E-Cadherin show expression patterns similar to FoxJ2, and the phenotypes of Connexin-43 and E-Cadherin mutants resemble those of our FoxJ2 transgenic animals. These data suggest that the lethal effect on embryonic development of FoxJ2 overexpression, as well as the alterations observed in the heart and testes of adult transgenic mice, could be determined by changes in the transcription of genes such as Connexin-43 and/or E-Cadherin.

The multiassembly problem: reconstructing multiple transcript isoforms from EST fragment mixtures

Recent evidence of abundant transcript variation (e.g., alternative splicing, alternative initiation, alternative polyadenylation) in complex genomes indicates that cataloging the complete set of transcripts from an organism is an important project. One challenge is the fact that most high-throughput experimental methods for characterizing transcripts (such as EST sequencing) give highly detailed information about short fragments of transcripts or protein products, instead of a complete characterization of a full-length form. We analyze this "multiassembly problem"-reconstructing the most likely set of full-length isoform sequences from a mixture of EST fragment data-and present a graph-based algorithm for solving it. In a variety of tests, we demonstrate that this algorithm deals appropriately with coupling of distinct alternative splicing events, increasing fragmentation of the input data and different types of transcript variation (such as alternative splicing, initiation, polyadenylation, and intron retention). To test the method's performance on pure fragment (EST) data, we removed all mRNA sequences, and found it produced no errors in 40 cases tested. Using this algorithm, we have constructed an Alternatively Spliced Proteins database (ASP) from analysis of human expressed and genomic sequences, consisting of 13,384 protein isoforms of 4422 genes, yielding an average of 3.0 protein isoforms per gene.

Foxj3, a novel mammalian forkhead gene expressed in neuroectoderm, neural crest, and myotome

Forkhead transcription factors are important regulators of animal development. Here, we describe the embryonic expression pattern for one of the novel forkhead genes that were discovered as a result of the mouse and human genome projects. It is most closely related to FoxJ2 and has been assigned the name FoxJ3. The 100-kb, 13-exon mouse Foxj3 gene on chromosome 4 encodes a 623 amino acid (aa) protein from an mRNA of at least 4.8 kb (Human FOXJ3: Chr 1, 627 aa, 5.3-kb mRNA). During the stages of mouse development investigated (embryonic day [E] 8.5-E12.5) Foxj3 is expressed in neuroectoderm, in neural crest, and in many structures derived from neural crest cells, such as facioacoustic, trigeminal, and dorsal root ganglia. Stripes of expression appear at E10.5 in the location of myotomes and expand ventrally in a pattern similar to the developing body wall musculature. Developing limbs have a complex pattern of Foxj3 expression that at E12.5 colocalizes with the condensed mesenchyme of the skeletal primordia.

Functional domains of FOXJ2

FOXJ2 is a fork head transcriptional activator, the expression of which starts very early in embryonic development and it is distributed widely in the adult. Here, we describe the characterization of domains that are important for its function. FOXJ2 is localized constitutively at the nucleus of the cell. Two tyrosine residues and a stretch of basic amino acid residues at the N and C-terminal ends of the fork head domain, respectively, are important for its nuclear targeting. These residues are conserved strongly among all members of the fork head family, suggesting that they could be involved in the nuclear translocation mechanism of all fork head factors. In addition to the AB domain, we have found, at least, two other transactivation domains: Domain I, at the N terminus, and the H/P domain, rich in histidine and proline residues. Although the AB domain shows the strongest transactivation capacity, all three domains are required for full FOXJ2 transcriptional activity. Furthermore, a fourth region rich in proline and glutamine residues and with no intrinsic transactivation function, the P/Q domain, appears to play an important role in the FOXJ2-mediated transactivation mechanism. Although FOXJ2 can be phosphorylated in two serine residues, this post-translational modification did not appear to be essential for transactivation. Finally, we have found that the W2 wing of the fork head domain of FOXJ2 is dispensable for specific DNA binding, although it could have a weak stabilizing role for the DNA-FOXJ2 complex.

Molecular analysis and developmental expression of the Sex-lethal gene of Sciara ocellaris (Diptera order, Nematocera suborder)

This paper reports the cloning and characterization in Sciara ocellaris of the gene homologous to Sex-lethal (Sxl) of Drosophila melanogaster. This gene plays the key role controlling sex determination and dosage compensation in the latter species. The Sciara Sxl gene produces a single transcript encoding a single protein in both males and females. This protein, found inside the nucleus, is expressed in all tissues. Both Sciara and Drosophila Sxl proteins are highly conserved at their two RNA-binding domains. In both Sciara sexes, the Sxl protein co-localizes with transcription-active regions dependent on RNA polymerase II but not on RNA polymerase I. It would appear that in Sciara, Sxl does not appear to play the key discriminative role in controlling sex determination and dosage compensation that it plays in Drosophila.