Transcription factors ER71/ETV2 and SOX9 participate in a positive feedback loop in fetal and adult mouse testis

Inefficient Sox9 upregulation and absence of Rspo1 repression lead to sex reversal in the B6.XYTIR mouse gonad†

Sry on the Y-chromosome upregulates Sox9, which in turn upregulates a set of genes such as Fgf9 to initiate testicular differentiation in the XY gonad. In the absence of Sry expression, genes such as Rspo1, Foxl2, and Runx1 support ovarian differentiation in the XX gonad. These two pathways antagonize each other to ensure the development of only one gonadal sex in normal development. In the B6.YTIR mouse, carrying the YTIR-chromosome on the B6 genetic background, Sry is expressed in a comparable manner with that in the B6.XY mouse, yet, only ovaries or ovotestes develop. We asked how testicular and ovarian differentiation pathways interact to determine the gonadal sex in the B6.YTIR mouse. Our results showed that (1) transcript levels of Sox9 were much lower than in B6.XY gonads while those of Rspo1 and Runx1 were as high as B6.XX gonads at 11.5 and 12.5 days postcoitum. (2) FOXL2-positive cells appeared in mosaic with SOX9-positive cells at 12.5 days postcoitum. (3) SOX9-positive cells formed testis cords in the central area while those disappeared to leave only FOXL2-positive cells in the poles or the entire area at 13.5 days postcoitum. (4) No difference was found at transcript levels of all genes between the left and right gonads up to 12.5 days postcoitum, although ovotestes developed much more frequently on the left than the right at 13.5 days postcoitum. These results suggest that inefficient Sox9 upregulation and the absence of Rspo1 repression prevent testicular differentiation in the B6.YTIR gonad.

Methylation of the JMJD2B epigenetic regulator differentially affects its ability to coactivate the ETV1 and JUN transcription factors

OBJECTIVES

Jumonji C domain-containing (JMJD) 2B (JMJD2B) is a transcriptional cofactor and histone demethylase that is involved in prostate cancer formation. However, how its function is regulated by posttranslational modification has remained elusive. Hence, we examined if JMJD2B would be regulated by lysine methylation.

METHODS

Through in vitro methylation assays and Western blotting with methyl-lysine specific antibodies, we analyzed lysine methylation within JMJD2B. Identified methylated lysine residues were mutated to arginine residues and the respective impact on JMJD2B transcriptional activity measured with a reporter gene assay in human LNCaP prostate cancer cells.

RESULTS

We discovered that JMJD2B is methylated on up to six different lysine residues. Further, we identified the suppressor of variegation 3-9/enhancer of zeste/trithorax (SET) domain-containing protein 7/9 (SET7/9) as the methyltransferase being responsible for this posttranslational modification. Mutating the methylation sites in JMJD2B to arginine residues led to diminished coactivation of the Ju-nana (JUN) transcription factor, which is a known oncogenic protein in prostate tumors. In contrast, methylation of JMJD2B had no impact on its ability to coactivate another transcription factor associated with prostate cancer, the DNA-binding protein E26 transformation-specific (ETS) variant 1 (ETV1). Consistent with a potential joint action of JMJD2B, SET7/9 and JUN in prostate cancer, the expression of JMJD2B in human prostate tumors was positively correlated with both SET7/9 and JUN levels.

CONCLUSIONS

The identified SET7/9-mediated methylation of JMJD2B appears to impact its cooperation with selected interacting transcription factors in prostate cancer cells. Given the implicated roles of JMJD2B beyond prostate tumorigenesis, SET7/9-mediated methylation of JMJD2B possibly also influences the development of other cancers, while its impairment might have relevance for obesity or a global developmental delay that can be elicited by reduced JMJD2B activity.

Methylation of the epigenetic JMJD2D protein by SET7/9 promotes prostate tumorigenesis

How the function of the JMJD2D epigenetic regulator is regulated or whether it plays a role in prostate cancer has remained elusive. We found that JMJD2D was overexpressed in prostate tumors, stimulated prostate cancer cell growth and became methylated by SET7/9 on K427. Mutation of this lysine residue in JMJD2D reduced the ability of DU145 prostate cancer cells to grow, invade and form tumors and elicited extensive transcriptomic changes. This included downregulation of CBLC, a ubiquitin ligase gene with hitherto unknown functions in prostate cancer, and upregulation of PLAGL1, a transcription factor with reported tumor suppressive characteristics in the prostate. Bioinformatic analyses indicated that CBLC expression was elevated in prostate tumors. Further, downregulation of CBLC largely phenocopied the effects of the K427 mutation on DU145 cells. In sum, these data have unveiled a novel mode of regulation of JMJD2D through lysine methylation, illustrated how this can affect oncogenic properties by influencing expression of the CBLC gene, and established a pro-tumorigenic role for CBLC in the prostate. A corollary is that JMJD2D and CBLC inhibitors could have therapeutic benefits in the treatment of prostate and possibly other cancers.

Promotion of colorectal cancer by transcription factor BHLHE40 involves upregulation of ADAM19 and KLF7

BHLHE40 is a transcription factor, whose role in colorectal cancer has remained elusive. We demonstrate that the BHLHE40 gene is upregulated in colorectal tumors. Transcription of BHLHE40 was jointly stimulated by the DNA-binding ETV1 protein and two associated histone demethylases, JMJD1A/KDM3A and JMJD2A/KDM4A, which were shown to also form complexes on their own and whose enzymatic activity was required for BHLHE40 upregulation. Chromatin immunoprecipitation assays revealed that ETV1, JMJD1A and JMJD2A interacted with several regions within the BHLHE40 gene promoter, suggesting that these three factors directly control BHLHE40 transcription. BHLHE40 downregulation suppressed both growth and clonogenic activity of human HCT116 colorectal cancer cells, strongly hinting at a pro-tumorigenic role of BHLHE40. Through RNA sequencing, the transcription factor KLF7 and the metalloproteinase ADAM19 were identified as putative BHLHE40 downstream effectors. Bioinformatic analyses showed that both KLF7 and ADAM19 are upregulated in colorectal tumors as well as associated with worse survival and their downregulation impaired HCT116 clonogenic activity. In addition, ADAM19, but not KLF7, downregulation reduced HCT116 cell growth. Overall, these data have revealed a ETV1/JMJD1A/JMJD2A→BHLHE40 axis that may stimulate colorectal tumorigenesis through upregulation of genes such as KLF7 and ADAM19, suggesting that targeting this axis represents a potential novel therapeutic avenue.

The regulatory role of pioneer factors during cardiovascular lineage specification – A mini review

Cardiovascular disease (CVD) remains the number one cause of death worldwide. Ischemic heart disease contributes to heart failure and has considerable morbidity and mortality. Therefore, alternative therapeutic strategies are urgently needed. One class of epigenetic regulators known as pioneer factors has emerged as an important tool for the development of regenerative therapies for the treatment of CVD. Pioneer factors bind closed chromatin and remodel it to drive lineage specification. Here, we review pioneer factors within the cardiovascular lineage, particularly during development and reprogramming and highlight the implications this field of research has for the future development of cardiac specific regenerative therapies.

Sumoylation of transcription factor ETV1 modulates its oncogenic potential in prostate cancer

The transcription factor ETS variant 1 (ETV1) is capable of promoting prostate tumorigenesis. We demonstrate that ETV1 can be posttranslationally modified by covalent attachment of small ubiquitin-like modifier 1 (SUMO1) onto four different lysine residues. In human embryonic kidney 293T cells, mutation of these sumoylation sites stimulated the transactivation potential of ETV1 at the matrix metalloproteinase 1 (MMP1), but not Yes-associated protein 1 gene promoter, while ETV1 protein stability and intracellular localization remained unchanged. In stark contrast, sumoylation-deficient ETV1 was repressed in its ability to stimulate the MMP1 promoter and to cooperate with a histone demethylase, JmjC domain-containing 2A (JMJD2A), in LNCaP prostate cancer cells. Mutation of sumoylation sites enhanced the ability of ETV1 to interact with the histone deacetylase (HDAC) 1, but had basically no impact on complex formation with HDAC3 or JMJD2A. Further, compared to non-sumoylated ETV1, its sumoylated forms were less able to bind to the transcription factor, SMAD family member 4. Lastly, in contrast to wild-type ETV1, sumoylation-deficient ETV1 repressed LNCaP cell growth. Altogether, these data suggest that sumoylation modulates ETV1 function in a cell type-specific manner, possibly by altering the spectrum of transcriptional cofactors being recruited. Notably, SUMO pathway components SUMO1, ubiquitin-like modifier activating enzyme 2 and ubiquitin conjugating enzyme 9 were upregulated in prostate tumors, implying that enhanced sumoylation indeed promotes ETV1's oncogenic activity during prostate cancer formation.

The T-box transcription factor Eomesodermin governs haemogenic competence of yolk sac mesodermal progenitors

Extra-embryonic mesoderm (ExM)-composed of the earliest cells that traverse the primitive streak-gives rise to the endothelium as well as haematopoietic progenitors in the developing yolk sac. How a specific subset of ExM becomes committed to a haematopoietic fate remains unclear. Here we demonstrate using an embryonic stem cell model that transient expression of the T-box transcription factor Eomesodermin (Eomes) governs haemogenic competency of ExM. Eomes regulates the accessibility of enhancers that the transcription factor stem cell leukaemia (SCL) normally utilizes to specify primitive erythrocytes and is essential for the normal development of Runx1+ haemogenic endothelium. Single-cell RNA sequencing suggests that Eomes loss of function profoundly blocks the formation of blood progenitors but not specification of Flk-1+ haematoendothelial progenitors. Our findings place Eomes at the top of the transcriptional hierarchy regulating early blood formation and suggest that haemogenic competence is endowed earlier during embryonic development than was previously appreciated.

Cooperation between ETS transcription factor ETV1 and histone demethylase JMJD1A in colorectal cancer

ETS variant 1 (ETV1) is an oncogenic transcription factor. However, its role in colorectal cancer has remained understudied. The present study demonstrated that ETV1 downregulation led to reduced HCT116 colorectal cancer cell growth and clonogenic activity. Furthermore, the ETV1 mRNA levels were enhanced in colorectal tumors and were associated with disease severity. In addition, ETV1 directly bound to Jumonji C domain-containing (JMJD) 1A, a histone demethylase known to promote colon cancer. ETV1 and JMJD1A, but not a catalytically inactive mutant thereof, cooperated in inducing the matrix metalloproteinase (MMP)1 gene promoter that was similar to the cooperation between ETV1 and another histone demethylase, JMJD2A. RNA-sequencing revealed multiple potential ETV1 target genes in HCT116 cells, including the FOXQ1 and TBX6 transcription factor genes. Moreover, JMJD1A co-regulated FOXQ1 and other ETV1 target genes, but not TBX6, whereas JMJD2A downregulation had no impact on FOXQ1 as well as TBX6 transcription. Accordingly, the FOXQ1 gene promoter was stimulated by ETV1 and JMJD1A in a cooperative manner, and both ETV1 and JMJD1A bound to the FOXQ1 promoter. Notably, the overexpression of FOXQ1 partially reversed the growth inhibitory effects of ETV1 ablation on HCT116 cells, whereas TBX6 impaired HCT116 cell growth and may thereby dampen the oncogenic activity of ETV1. The latter also revealed for the first time, to the best of our knowledge, a potential tumor suppressive function of TBX6. Taken together, the present study uncovered a ETV1/JMJD1A-FOXQ1 axis that may drive colorectal tumorigenesis.

Opposite Roles of the JMJD1A Interaction Partners MDFI and MDFIC in Colorectal Cancer

MyoD family inhibitor (MDFI) and MDFI domain-containing (MDFIC) are homologous proteins known to regulate myogenic transcription factors. Hitherto, their role in cancer is unknown. We discovered that MDFI is up- and MDFIC downregulated in colorectal tumors. Mirroring these different expression patterns, MDFI stimulated and MDFIC inhibited growth of HCT116 colorectal cancer cells. Further, MDFI and MDFIC interacted with Jumonji C domain-containing (JMJD) 1 A, a histone demethylase and epigenetic regulator involved in colorectal cancer. JMJD1A influenced transcription of several genes that were also regulated by MDFI or MDFIC. Notably, the HIC1 tumor suppressor gene was stimulated by JMJD1A and MDFIC, but not by MDFI, and HIC1 overexpression phenocopied the growth suppressive effects of MDFIC in HCT116 cells. Similar to colorectal cancer, MDFI was up- and MDFIC downregulated in breast, ovarian and prostate cancer, but both were overexpressed in brain, gastric and pancreatic tumors that implies MDFIC to also promote tumorigenesis in certain tissues. Altogether, our data suggest a tumor modulating function for MDFI and MDFIC in colorectal and other cancers that may involve their interaction with JMJD1A and a MDFIC→HIC1 axis.

Relationship between ETS Transcription Factor ETV1 and TGF-β-regulated SMAD Proteins in Prostate Cancer

The ETS transcription factor ETV1 is frequently overexpressed in aggressive prostate cancer, which is one underlying cause of this disease. Accordingly, transgenic mice that prostate-specifically overexpress ETV1 develop prostatic intraepithelial neoplasia. However, progression to the adenocarcinoma stage is stifled in these mice, suggesting that inhibitory pathways possibly preclude ETV1 from exerting its full oncogenic potential. Here we provide evidence that TGF-β/SMAD signaling represents such an inhibitory pathway. First, we discovered that ETV1 forms complexes with SMAD4. Second, SMAD2, SMAD3 and SMAD4 overexpression impaired ETV1’s ability to stimulate gene transcription. Third, TGF-β1 inhibited ETV1-induced invasion by benign RWPE-1 prostate cells. Fourth, increased expression of SMAD3 and SMAD4 was observable in prostates of ETV1 transgenic mice. Conversely, we found that ETV1 may enhance TGF-β signaling in PC3 prostate cancer cells, revealing a different facet of the ETV1/TGF-β interplay. Altogether, these data provide more insights into the regulation and action of ETV1 and additionally suggest that TGF-β/SMAD signaling exerts its tumor suppressive activity, at least in part, by curtailing the oncogenic potential of ETV1 in prostatic lesions.

Regulation of CATSPER1 expression by the testis-determining gene SRY

CATSPER1 gene encodes a pore-forming and pH-sensing subunit of the CatSper Ca²⁺- permeable channel, a protein in the flagellum essential for sperm hyperactivation. Previous studies have shown that the murine Catsper1 gene promoter is regulated by different Sox proteins. Likewise, it is acknowledged that the human CATSPER1 gene promoter sequence is enriched in potential interaction sites for the sex-determining region Y gene (SRY), which suggest a novel regulatory transcriptional mechanism for CatSper1 channel expression. Therefore, in this work, we sought to determine whether the human CATSPER1 gene expression is regulated by the SRY transcription factor. To this end, a series of deletions and mutations were introduced in the wild- type CATSPER1 gene promoter to eliminate the SRY sites, and the different constructs were tested for their ability to activate transcription in human embryonic kidney and murine spermatogonial germ cell lines (HEK-293 and GC1-spg, respectively) using luciferase assays. In addition, by using a strategy that combines electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) we investigated whether the CATSPER1 gene expression is regulated by the SRY transcription factor both in vitro and in vivo. Our results show that the transcriptional factor SRY specifically binds to different sites in the promoter sequence and has the ability to control CATSPER1 gene transcription.

Etv2 as an essential regulator of mesodermal lineage development

The 'master regulatory factors' that position at the top of the genetic hierarchy of lineage determination have been a focus of intense interest, and have been investigated in various systems. Etv2/Etsrp71/ER71 is such a factor that is both necessary and sufficient for the development of haematopoietic and endothelial lineages. As such, genetic ablation of Etv2 leads to complete loss of blood and vessels, and overexpression can convert non-endothelial cells to the endothelial lineage. Understanding such master regulatory role of a lineage is not only a fundamental quest in developmental biology, but also holds immense possibilities in regenerative medicine. To harness its activity and utility for therapeutic interventions, it is essential to understand the regulatory mechanisms, molecular function, and networks that surround Etv2. In this review, we provide a comprehensive overview of Etv2 biology focused on mouse and human systems.

Coordination of meristem and boundary functions by transcription factors in the SHOOT MERISTEMLESS regulatory network

The Arabidopsis homeodomain transcription factor SHOOT MERISTEMLESS (STM) is crucial for shoot apical meristem (SAM) function, yet the components and structure of the STM gene regulatory network (GRN) are largely unknown. Here, we show that transcriptional regulators are overrepresented among STM-regulated genes and, using these as GRN components in Bayesian network analysis, we infer STM GRN associations and reveal regulatory relationships between STM and factors involved in multiple aspects of SAM function. These include hormone regulation, TCP-mediated control of cell differentiation, AIL/PLT-mediated regulation of pluripotency and phyllotaxis, and specification of meristem-organ boundary zones via CUC1. We demonstrate a direct positive transcriptional feedback loop between STM and CUC1, despite their distinct expression patterns in the meristem and organ boundary, respectively. Our further finding that STM activates expression of the CUC1-targeting microRNA miR164c combined with mathematical modelling provides a potential solution for this apparent contradiction, demonstrating that these proposed regulatory interactions coupled with STM mobility could be sufficient to provide a mechanism for CUC1 localisation at the meristem-organ boundary. Our findings highlight the central role for the STM GRN in coordinating SAM functions.

Cooperation between ETS variant 2 and Jumonji domain‑containing 2 histone demethylases

The E26 transformation-specific (ETS) variant 2 (ETV2) protein, also designated as ETS-related 71, is a member of the ETS transcription factor family and is essential for blood and vascular development in the embryo. The role of ETV2 in cancer has not yet been investigated. In the present study, the expression of ETV2 mRNA was identified in a variety of tumor types, including prostate carcinoma. In addition, ETV2 gene amplification was identified in several types of cancer, suggesting that ETV2 plays an oncogenic role in tumorigenesis. It was demonstrated that ETV2 forms complexes with two histone demethylases: Jumonji domain-containing (JMJD)2A and JMJD2D; JMJD2A has been previously reported as a driver of prostate cancer development. In the present study, it was reported that ETV2 exhibited the potential to stimulate the promoters of matrix metalloproteinases (MMPs), including MMP1 and MMP7, within LNCaP prostate cancer cells. JMJD2A and JMJD2D could synergize with ETV2 to activate the MMP1 promoter, whereas only JMJD2A stimulated the MMP7 promoter in cooperation with ETV2. Furthermore, ETV2 expression was positively associated with JMJD2A and JMJD2D mRNA levels in neuroendocrine prostate tumors, in which an ETV2 gene amplification rate of 17.8% was identified. Collectively, the results of the present study indicated that ETV2, JMJD2A and JMJD2D may jointly promote tumorigenesis, particularly neuroendocrine prostate tumors. In addition, the interaction with the JMJD2A and JMJD2D epigenetic regulators may be important in the ability of ETV2 to reprogram cells, modulate normal and cancer stem cells, and affect spermatogenesis.

Multiple-trait genomewide mapping and gene network analysis for scrotal circumference growth curves in Brahman cattle

Fertility traits are economically important in cattle breeding programs. Scrotal circumference (SC) measures are repeatable, easily obtained, highly heritable, and positively correlated with female fertility traits and sperm quality traits in males. A useful approach to summarize SC measures over time is using nonlinear models, which summarize specific measures of SC in a few parameters with biological interpretation. This approach facilitates the selection of bulls with larger SC and maturity index (K), that is, early maturing animals. Because SC is a sex-limited trait, identifying the underlying genomics of growth curve parameters will allow selection across both males and females. We reported the first multitrait genomewide association study (GWAS) of estimated growth curve parameters for SC data in Brahman cattle. Five widely used nonlinear models were tested to fit a total of 3,612 SC records, measured at 6, 12, 18, and 24 mo of age. The von Bertalanffy model, individually fitted for each animal, best fit this SC data. Parameter estimates SC at maturity (A) and K as well as SC at all ages were jointly analyzed in a GWAS to identify 1-Mb regions most strongly associated with each trait. Heritabilities were 0.25 for K and 0.32 for A and ranged from 0.51 to 0.72 for SC at 6 (SC6), 12 (SC12), 18 (SC18), and 24 mo of age (SC24). An overlapping window on chromosome 14 explaining around 0.8% of genetic variance for K, SC12, SC18, and SC24 was observed. The major positional candidate genes within 1 Mb upstream and downstream of this overlapping window were , , , and . Windows of 1 Mb explaining more than 0.4% of each trait on chromosomes 1, 3, 6, 7, 14, 17, 18, 24, 25, and 26 were identified. Pathways and net-work analyses were indicated through transcription factors playing a role on fertility traits: , , , , , , and . Further validation studies on larger populations or other breeds are required to validate these findings and to improve our understanding of the biology and complex genetic architecture of traits associated with scrotal growth and male fertility in cattle.

The Isl1-Lhx3 Complex Promotes Motor Neuron Specification by Activating Transcriptional Pathways that Enhance Its Own Expression and Formation

Motor neuron (MN) progenitor cells rapidly induce high expression of the transcription factors Islet-1 (Isl1), LIM-homeobox 3 (Lhx3), and the transcriptional regulator LMO4, as they differentiate. While these factors are critical for MN specification, the mechanisms regulating their precise temporal and spatial expression patterns are not well characterized. Isl1 and Lhx3 form the Isl1-Lhx3 complex, which induces the transcription of genes critical for MN specification and maturation. Here, we report that Isl1, Lhx3, and Lmo4 are direct target genes of the Isl1-Lhx3 complex. Our results show that specific genomic loci associated with these genes recruit the Isl1-Lhx3 complex to activate the transcription of Isl1, Lhx3, and Lmo4 in embryonic MNs of chick and mouse. These findings support a model in which the Isl1-Lhx3 complex amplifies its own expression through a potent autoregulatory feedback loop and simultaneously enhances the transcription of Lmo4. LMO4 blocks the formation of the V2 interneuron-specifying Lhx3 complex. In developing MNs, this action inhibits the expression of V2 interneuron genes and increases the pool of unbound Lhx3 available to incorporate into the Isl1-Lhx3 complex. Identifying the pathways that regulate the expression of these key factors provides important insights into the genetic strategies utilized to promote MN differentiation and maturation.

Loss of p27Kip¹ promotes metaplasia in the pancreas via the regulation of Sox9 expression

p27^Kip1 (p27) is a negative regulator of proliferation and a tumor suppressor via the inhibition of cyclin-CDK activity in the nucleus. p27 is also involved in the regulation of other cellular processes, including transcription by acting as a transcriptional co-repressor. Loss of p27 expression is frequently observed in pancreatic adenocarcinomas in human and is associated with decreased patient survival. Similarly, in a mouse model of K-Ras-driven pancreatic cancer, loss of p27 accelerates tumor development and shortens survival, suggesting an important role for p27 in pancreatic tumorigenesis. Here, we sought to determine how p27 might contribute to early events leading to tumor development in the pancreas. We found that K-Ras activation in the pancreas causes p27 mislocalization at pre-neoplastic stages. Moreover, loss of p27 or expression of a mutant p27 that does not bind cyclin-CDKs causes the mislocalization of several acinar polarity markers associated with metaplasia and induces the nuclear expression of Sox9 and Pdx1 two transcription factors involved in acinar-to-ductal metaplasia. Finally, we found that p27 directly represses transcription of Sox9, but not that of Pdx1. Thus, our results suggest that K-Ras activation, the earliest known event in pancreatic carcinogenesis, may cause loss of nuclear p27 expression which results in derepression of Sox9, triggering reprogrammation of acinar cells and metaplasia.

Molecular mechanism of male differentiation is conserved in the SRY-absent mammal, Tokudaia osimensis

The sex-determining gene SRY induces SOX9 expression in the testes of eutherian mammals via two pathways. SRY binds to testis-specific enhancer of Sox9 (TESCO) with SF1 to activate SOX9 transcription. SRY also up-regulates ER71 expression, and ER71 activates Sox9 transcription. After the initiation of testis differentiation, SOX9 enhances Amh expression by binding to its promoter with SF1. SOX8, SOX9 and SOX10, members of the SOXE gene family, also enhance the activities of the Amh promoter and TESCO. In this study, we investigated the regulation of these sexual differentiation genes in Tokudaia osimensis, which lacks a Y chromosome and the SRY gene. The activity of the AMH promoter was stimulated by SOXE genes and SF1. Mutant AMH promoters, with mutations in its SOX and SF1 binding sites, did not show significant activity by SOX9 and SF1. These results indicate that AMH expression was regulated by the binding of SOX9 and SF1. By contrast, SOXE genes could not enhance TESCO activity. These results indicate that TESCO enhancer activity was lost in this species. Furthermore, the activity of the SOX9 promoter was enhanced by ER71, indicating that ER71 may play an important role in the testis-specific expression of SOX9.

Upregulation of PSMD10 caused by the JMJD2A histone demethylase

PSMD10, also known as gankyrin, is associated with the proteasome and has been shown to be an oncoprotein in the liver. Here, we report that PSMD10 expression is stimulated by the histone demethylase JMJD2A/KDM4A and its interaction partner, the ETV1 transcription factor, in LNCaP prostate cancer cells. Global analysis of expression patterns revealed that PSMD10 mRNA levels are positively correlated with those of both JMJD2A and ETV1. In human prostate tumors, PSMD10 is highly overexpressed at the protein level and correlates with JMJD2A overexpression; further, PSMD10 expression is enhanced in the prostates of transgenic JMJD2A mice. Moreover, PSMD10 is particularly overexpressed in high Gleason score prostate tumors. Downregulation of PSMD10 in LNCaP prostate cancer cells impaired their growth, indicating that PSMD10 may exert a pro-oncogenic function in the prostate. Lastly, we observed that PSMD10 expression is correlated to YAP1, a component of the Hippo signaling pathway and whose gene promoter is regulated by JMJD2A, and that PSMD10 can cooperate with YAP1 in stimulating LNCaP cell growth. Altogether, these data indicate that PSMD10 is a novel downstream effector of JMJD2A and suggest that inhibition of the JMJD2A histone demethylase by small molecule drugs may be effective to curtail the oncogenic activity of PSMD10 in various PSMD10-overexpressing tumors.

ETS transcription factor ERG cooperates with histone demethylase KDM4A

ERG (ETS-related gene) is a member of the ETS (erythroblast transformation-specific) family of transcription factors. Overexpression of the ERG transcription factor is observed in half of all prostate tumors and is an underlying cause of this disease. However, the mechanisms involved in the functions of ERG are still not fully understood. In the present study, we showed that ERG can directly bind to KDM4A (also known as JMJD2A), a histone demethylase that particularly demethylates lysine 9 on histone H3. ERG and KDM4A cooperated in upregulating the promoter of Yes-associated protein 1 (YAP1), a downstream effector in the Hippo signaling pathway and crucial growth regulator. Multiple ERG binding sites within the human YAP1 gene promoter were identified and their impact on transcription was determined through mutational analysis. Furthermore, we found that ERG expression reduced histone H3 lysine 9 trimethylation at the YAP1 gene promoter, consistent with its epigenetic regulation through the ERG interaction partner, KDM4A. Finally, downregulation of YAP1 phenocopied the growth-retarding effect of ERG or KDM4A depletion in human VCaP prostate cancer cells. Collectively, these results elucidated a novel mechanism - ERG promotes prostate tumorigenesis together with KDM4A through the upregulation of YAP1. A corollary is that KDM4A as well as YAP1 inhibitors may prove beneficial for the therapy of ERG-overexpressing prostate tumors.

Histone demethylase JMJD2A drives prostate tumorigenesis through transcription factor ETV1

Histone demethylase upregulation has been observed in human cancers, yet it is unknown whether this is a bystander event or a driver of tumorigenesis. We found that overexpression of lysine-specific demethylase 4A (KDM4A, also known as JMJD2A) was positively correlated with Gleason score and metastasis in human prostate tumors. Overexpression of JMJD2A resulted in the development of prostatic intraepithelial neoplasia in mice, demonstrating that JMJD2A can initiate prostate cancer development. Moreover, combined overexpression of JMJD2A and the ETS transcription factor ETV1, a JMJD2A-binding protein, resulted in prostate carcinoma formation in mice haplodeficient for the phosphatase and tensin homolog (Pten) tumor-suppressor gene. Additionally, JMJD2A cooperated with ETV1 to increase expression of yes associated protein 1 (YAP1), a Hippo pathway component that itself was associated with prostate tumor aggressiveness. ETV1 facilitated the recruitment of JMJD2A to the YAP1 promoter, leading to changes in histone lysine methylation in a human prostate cancer cell line. Further, YAP1 expression largely rescued the growth inhibitory effects of JMJD2A depletion in prostate cancer cells, indicating that YAP1 is a downstream effector of JMJD2A. Taken together, these data reveal a JMJD2A/ETV1/YAP1 axis that promotes prostate cancer initiation and that may be a suitable target for therapeutic inhibition.

Vascular endothelial growth factor A: just one of multiple mechanisms for sex-specific vascular development within the testis?

Testis development from an indifferent gonad is a critical step in embryogenesis. A hallmark of testis differentiation is sex-specific vascularization that occurs as endothelial cells migrate from the adjacent mesonephros into the testis to surround Sertoli-germ cell aggregates and induce seminiferous cord formation. Many in vitro experiments have demonstrated that vascular endothelial growth factor A (VEGFA) is a critical regulator of this process. Both inhibitors to VEGFA signal transduction and excess VEGFA isoforms in testis organ cultures impaired vascular development and seminiferous cord formation. However, in vivo models using mice which selectively eliminated all VEGFA isoforms: in Sertoli and germ cells (pDmrt1-Cre;Vegfa(-/-)); Sertoli and Leydig cells (Amhr2-Cre;Vegfa(-/-)) or Sertoli cells (Amh-Cre;Vegfa(-/-) and Sry-Cre;Vegfa(-/-)) displayed testes with observably normal cords and vasculature at postnatal day 0 and onwards. Embryonic testis development may be delayed in these mice; however, the postnatal data indicate that VEGFA isoforms secreted from Sertoli, Leydig or germ cells are not required for testis morphogenesis within the mouse. A Vegfa signal transduction array was employed on postnatal testes from Sry-Cre;Vegfa(-/-) versus controls. Ptgs1 (Cox1) was the only upregulated gene (fivefold). COX1 stimulates angiogenesis and upregulates, VEGFA, Prostaglandin E2 (PGE2) and PGD2. Thus, other gene pathways may compensate for VEGFA loss, similar to multiple independent mechanisms to maintain SOX9 expression. Multiple independent mechanism that induce vascular development in the testis may contribute to and safeguard the sex-specific vasculature development responsible for inducing seminiferous cord formation, thus ensuring appropriate testis morphogenesis in the male.

Pro-growth role of the JMJD2C histone demethylase in HCT-116 colon cancer cells and identification of curcuminoids as JMJD2 inhibitors

Colon tumors are a major cause of cancer death, yet their molecular intricacies are not fully understood. We demonstrate that the histone demethylases JMJD2A, JMJD2B and JMJD2C are overexpressed in colon cancer cell lines, whereas another related protein, JMJD2D, is not. Interestingly, despite their high homology, the intracellular localization of JMJD2A-C is different in colon and other cancer cells, with JMJD2A being present comparably in the cytoplasm and nucleus, JMJD2B more prevalent in the nucleus and JMJD2C strongly associated with chromatin. This suggests that each of these three proteins performs different, non-redundant functions. Moreover, we show that JMJD2C (also called KDM4C) forms complexes with β-catenin, an oncoprotein whose overexpression is crucial for the development of most colonic tumors. In addition, JMJD2C downregulation reduced both growth and clonogenic capacity of HCT-116 colon cancer cells. Further, JMJD2C was required for efficient expression of the growth stimulatory proteins FRA1 and cyclin D1 as well as the survival factor BCL2. Lastly, we identified derivatives of curcumin as in vitro inhibitors of JMJD2 enzymes, suggesting that these curcuminoids could be useful for decreasing JMJD2 activity in vivo. In conclusion, our data highlight that overexpression of JMJD2C confers a pro-growth effect on colon cancer cells and, therefore, its inhibition by curcuminoids or other small molecules could be beneficial as an adjuvant therapy for colon cancer patients.

Understanding the role of ETS-mediated gene regulation in complex biological processes

Ets factors are members of one of the largest families of evolutionarily conserved transcription factors, regulating critical functions in normal cell homeostasis, which when perturbed contribute to tumor progression. The well-documented alterations in ETS factor expression and function during cancer progression result in pleiotropic effects manifested by the downstream effect on their target genes. Multiple ETS factors bind to the same regulatory sites present on target genes, suggesting redundant or competitive functions. The anti- and prometastatic signatures obtained by examining specific ETS regulatory networks will significantly improve our ability to accurately predict tumor progression and advance our understanding of gene regulation in cancer. Coordination of multiple ETS gene functions also mediates interactions between tumor and stromal cells and thus contributes to the cancer phenotype. As such, these new insights may provide a novel view of the ETS gene family as well as a focal point for studying the complex biological control involved in tumor progression. One of the goals of molecular biology is to elucidate the mechanisms that contribute to the development and progression of cancer. Such an understanding of the molecular basis of cancer will provide new possibilities for: (1) earlier detection, as well as better diagnosis and staging of disease; (2) detection of minimal residual disease recurrences and evaluation of response to therapy; (3) prevention; and (4) novel treatment strategies. Increased understanding of ETS-regulated biological pathways will directly impact these areas.

Stimulation of β-catenin and colon cancer cell growth by the KDM4B histone demethylase

The linchpin of colorectal cancer is the oncoprotein and transcriptional cofactor β-catenin, whose overexpression is causative for the neoplastic transformation of colon cells. However, the molecular details of β-catenin dependent gene transcription in cancer cells are still not comprehensively explored. Here, we show that the histone demethylase KDM4B was upregulated in colon and rectal adenocarcinomas and required for efficient growth and clonogenic activity of human HT-29 colon cancer cells. Moreover, KDM4B formed complexes with β-catenin in vitro and in vivo, which involved its central amino acids 353-740. In addition, KDM4B also interacted with the DNA-binding protein TCF4, which is the main factor recruiting β-catenin to chromatin in the intestine. KDM4B downregulation resulted in reduced expression of the β-catenin/TCF4 target genes JUN, MYC and Cyclin D1, all of which encode for oncoproteins. Collectively, our data indicate that KDM4B overexpression supports β-catenin mediated gene transcription and thereby contributes to the genesis of colorectal tumors. Accordingly, inhibition of the KDM4B histone demethylase may represent a novel avenue of fighting colorectal cancer, one of the major causes of cancer death throughout the world.

Role of Etv2-positive cells in the remodeling morphogenesis during vascular development

Etv2 is a critical determinant for the commitment of endothelial (EC) and hematopoietic (HPC) cells from mesoderm. Etv2 is assumed to be transiently required for EC commitment but dispensable after most ECs differentiate around E9.5. To confirm the time window of Etv2 requirement, Etv2 was ablated at different time points using ROSA26CreER mice. Unexpectedly, Etv2 ablation at E9.5 caused vascular remodeling defects in cranial and yolk sac vasculature. Immunostaining showed that Etv2+/VE-cadherin (VECAD)- cells were present around forming vasculature, mostly co-expressing Flk-1 with a small number of Etv2+/VECAD+ cells, indicating that Etv2+/Flk-1+/VECAD- cells are the major Etv2+ population promoting vascular remodeling around E9.5. Gene expression analysis showed up-regulation of Fgf proteins, Il-6, Glypican-3 and matrix metalloproteases in Etv2+/VEDAC- cells over Etv2-/VECAD+ mature ECs. Blockade of those factors caused reduced EC sprouting in ex vivo explant culture from E9.5 embryos, suggesting the functional significance of environmental factors derived from Etv2+ cells. Altogether, we propose that Etv2+/VEDAC- cells around E9.5-E10.5 provide extracellular factors to complete vascular morphogenesis in addition to becoming differentiated ECs incorporated into vessels. This insight for the new role of Ets protein in perivascular Flk-1+/VECAD-/(Etv2+) cells to induce expression of angiogenic factors may provide another strategy to control angiogenesis.

14-3-3 proteins modulate the ETS transcription factor ETV1 in prostate cancer

Overexpression of the ETS-related transcription factor ETV1 can initiate neoplastic transformation of the prostate. ETV1 activity is highly regulated by phosphorylation, but the underlying mechanisms are unknown. Here we report that all 14-3-3 proteins, with the exception of the tumor suppressor 14-3-3σ, can bind to ETV1 in a condition manner dictated by its prominent phosphorylation site S216. Non-σ 14-3-3 proteins synergized with ETV1 to activate transcription of its target genes MMP-1 and MMP-7, which regulate extracellular matrix in the prostate tumor microenvironment. S216 mutation or 14-3-3τ downregulation was sufficient to reduce ETV1 protein levels in prostate cancer cells, indicating that non-σ 14-3-3 proteins protect ETV1 from degradation. Notably, S216 mutation also decreased ETV1-dependent migration and invasion in benign prostate cells. Downregulation of 14-3-3τ reduced prostate cancer cell invasion and growth in the same manner as ETV1 attenuation. Finally, we showed that 14-3-3τ and 14-3-3ε were overexpressed in human prostate tumors. Taken together, our results showed that non-σ 14-3-3 proteins are important modulators of ETV1 function that promote prostate tumorigenesis.