Rad51 Regulates Reprogramming Efficiency through DNA Repair Pathway.

Rad51 is a key component of homologous recombination (HR) to repair DNA double-strand breaks and it forms Rad51 recombinase filaments of broken single-stranded DNA to promote HR. In addition to its role in DNA repair and cell cycle progression, Rad51 contributes to the reprogramming process during the generation of induced pluripotent stem cells. In light of this, we performed reprogramming experiments to examine the effect of co-expression of Rad51 and four reprogramming factors, Oct4, Sox2, Klf4, and c-Myc, on the reprogramming efficiency. Co-expression of Rad51 significantly increased the numbers of alkaline phosphatase-positive colonies and embryonic stem cell-like colonies during the process of reprogramming. Co-expression ofRad51 significantly increased the expression of epithelial markers at an early stage of reprogramming compared with control cells. Phosphorylated histone H2AX (γH2AX), which initiates the DNA double-strand break repair system, was highly accumulated in reprogramming intermediates upon co-expression of Rad51. This study identified a novel role of Rad51 in enhancing the reprogramming efficiency, possibly by facilitating mesenchymal-to-epithelial transition and by regulating a DNA damage repair pathway during the early phase of the reprogramming process.

Novel Function of Sprouty4 as a Regulator of Stemness and Differentiation of Embryonic Stem Cells.

Sprouty (Spry) genes encode inhibitors of the receptor tyrosine kinase signaling cascade, which plays important roles in stem cells. However, the role of Spry4 in the stemness of embryonic stem cells has not been fully elucidated. Here, we used mouse embryonic stem cells (mESCs) as a model system to investigate the role of Spry4 in the stem cells. Suppression of Spry4 expression results in the decreases of cell proliferation, EB formation and stemness marker expression, suggesting that Spry4 activity is associated with stemness of mESCs. Teratoma assay showed that the cartilage maturation was facilitated in Spry4 knocked down mESCs. Our results suggest that Spry4 is an important regulator of the stemness and differentiation of mESCs.

PI3K/Akt/mTOR activation by suppression of ELK3 mediates chemosensitivity of MDA-MB-231 cells to doxorubicin by inhibiting autophagy.

Drug resistance in breast cancer remains a major obstacle of clinical therapy. We found that suppression of ELK3 in the triple negative breast cancer cell line MDA-MB-231 impaired autophagy and led to a hypersensitive response to doxorubicin treatment. In ELK3-knockdown MDA-MB-231 cells (ELK3 KD), autophagy was not activated under starvation conditions, which is a major stimulus of autophagy activation. We revealed that activation of the PI3K/Akt pathway was the main cause of impaired autophagy in ELK3 KD. Our results suggest that targeting ELK3 may be a potential approach to overcome doxorubicin resistance in breast cancer therapeutics.

Ell3 stabilizes p53 following CDDP treatment via its effects on ubiquitin-dependent and -independent proteasomal degradation pathways in breast cancer cells.

The tumor suppressor protein p53 is unstable in quiescent cells and undergoes proteosomal degradation. Under conditions of cellular stress, p53 is rapidly stabilized by post-translational modification, thereby escaping degradation and translocating to the nucleus where it activates genes related to cell cycle arrest or apoptosis. Here, we report that the transcription elongation factor Ell3 sensitizes luminal type-cancer cell line, MCF7, which have wild-type p53, to the chemotherapeutic agent cis-diamminedichloroplatinum(II) (CDDP) by stabilizing p53. Overexpression of Ell3 in MCF7 cells suppressed the MDM2-mediated ubiquitin-dependent degradation pathway. In addition, Ell3 promoted binding of p53 to NADH quinone oxidoreductase 1, which is linked to the ubiquitin-independent degradation of p53. We found that Ell3 activates interleukin-20 (IL20) expression, which is linked to the ERK1/2 signaling pathway. Chemical inhibition of ERK1/2 signaling or molecular suppression of IL20 revealed that the ERK1/2 signaling pathway and IL20 are the main causes of p53 stabilization in Ell3-overexpressing MCF7 cells. These findings suggest that the ERK1/2 pathway can be targeted in the rational development of therapies to induce chemosensitization of breast cancer cells.

Novel Function of Lysine Methyltransferase G9a in the Regulation of Sox2 Protein Stability.

G9a is a lysine methyltransferase (KMTase) for histone H3 lysine 9 that plays critical roles in a number of biological processes. Emerging evidence suggests that aberrant expression of G9a contributes to tumor metastasis and maintenance of a malignant phenotype in cancer by inducing epigenetic silencing of tumor suppressor genes. Here, we show that G9a regulates Sox2 protein stability in breast cancer cells. When G9a lysine methyltransferase activity was chemically inhibited in the ER(+) breast cancer cell line MCF7, Sox2 protein levels were decreased. In addition, ectopic overexpression of G9a induced accumulation of Sox2. Changes in cell migration, invasion, and mammosphere formation by MCF7 cells were correlated with the activity or expression level of G9a. Ectopic expression of G9a also increased Sox2 protein levels in another ER(+) breast cancer cell line, ZR-75-1, whereas it did not affect Sox2 expression in MDA-MB-231 cells, an ER(-) breast cancer cell line, or in glioblastoma cell lines. Furthermore, treatment of mouse embryonic stem cells with a KMT inhibitor, BIX-01294, resulted in a rapid reduction in Sox2 protein expression despite increased Sox2 transcript levels. This finding suggests that G9a has a novel function in the regulation of Sox2 protein stability in a cell type-dependent manner.

The expression of aminoacyl-tRNA-synthetase-interacting multifunctional protein-1 (Aimp1) is regulated by estrogen in the mouse uterus.

Aimp1 is known as a multifunctional cytokine in various cellular events. Recent study showed Aimp1 is localized in glandular epithelial, endothelial, and stromal cells in functionalis and basalis layers of the endometrium. However, the regulatory mechanism of Aimp1 in the uterus remains unknown. In the present study, we found that Aimp1 is expressed in the mouse uterus. Aimp1 transcripts were decreased at diestrus stage. However, the level of Aimp1 protein was significantly increased in the luminal epithelium in the uterine endometrium at estrus stage during the estrous cycle. We found that treatment of estrogen increased the expression of Aimp1 in the uterus in ovarectomized mice. We identified one estrogen receptor binding element (ERE) on mouse Aimp1 promoter. The activity of Aimp1 promoter was increased with estrogen treatment. Our findings indicate that Aimp1 might act as an important regulator to remodel the uterine endometrium and its expression might be regulated by estrogen during the estrous cycle. This will give us better understanding of the dynamic change of uterine remodeling during the estrous cycle.

Diplotyper: diplotype-based association analysis.

BACKGROUND: It was previously reported that an association analysis based on haplotype clusters increased power over single-locus tests, and that another association test based on diplotype trend regression analysis outperformed other, more common association approaches. We suggest a novel algorithm to combine haplotype cluster- and diplotype-based analyses. METHODS: Diplotyper combines a novel algorithm designed to cluster haplotypes of interest from a given set of haplotypes with two existing tools: Haploview, for analyses of linkage disequilibrium blocks and haplotypes, and PLINK, to generate all possible diplotypes from given genotypes of samples and calculate linear or logistic regression. In addition, procedures for generating all possible diplotypes from the haplotype clusters and transforming these diplotypes into PLINK formats were implemented. RESULTS: Diplotyper is a fully automated tool for performing association analysis based on diplotypes in a population. Diplotyper was tested through association analysis of hepatic lipase (LIPC) gene polymorphisms or diplotypes and levels of high-density lipoprotein (HDL) cholesterol. CONCLUSIONS: Diplotyper is useful for identifying more precise and distinct signals over single-locus tests.

Epistasis between the HSD17B4 and TG polymorphisms is associated with premature ovarian failure.

OBJECTIVE: To identify whether epistasis between TG and HSD17B4 and whether polymorphisms in HSD17B4 are associated with premature ovarian failure (POF). DESIGN: Case-control genetic association study. SETTING: Research laboratory of a university. PATIENT(S): Female patients with POF (98) and controls (218) of Korean ethnicity participated in this study. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Genotype distribution, haplotype (HT) inference, and gene-gene interaction. RESULT(S): Distribution of one haplotype (A-G-A-A-G-G) on the HSD17B4 gene was significantly different between the POF group and the control group in a dominant model. In addition, the combined effect of the single nucleotide polymorphisms (SNPs) HSD17B4 rs28943592 and TG rs2076740 was significantly associated with POF (odds ratio = 7.74, 95% confidence interval = 1.67-35.94), although a significant association was not observed in the single SNP model. CONCLUSION(S): A haplotype in the HSD17B4 gene was identified that was significantly associated with resistance to POF. In addition, epistasis between two missense SNPs (rs28943592, rs2076740) located in HSD17B4 and TG was significantly associated with susceptibility to POF.

Effective delivery of anti-miRNA DNA oligonucleotides by functionalized gold nanoparticles.

MicroRNAs (miRNAs) are gaining recognition as essential regulators involved in many biological processes, and they are emerging as therapeutic targets for treating disease. Here, we introduce a method for effective delivery of anti-miRNA oligonucleotides (AMOs) using functionalized gold nanoparticles (AuNPs). To demonstrate the ability of AMOs to silence miRNA, we selected miR-29b, which is known to downregulate myeloid cell leukemia-1 (MCL-1), a factor responsible for promoting cell survival. We first generated AuNPs coated with cargo DNA, which was then coupled to complementary DNA linked to an antisense miR-29b sequence. When the AuNPs were delivered into HeLa cells, MCL-1 protein and mRNA levels were increased significantly. Furthermore, apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was inhibited, proving that AMOs targeting miR-29b were effectively delivered by our innovative AuNP. In addition, we provided evidence that AuNP could deliver other AMOs against miR-21 into two independent cell lines, KGN and 293T, suggesting that the AuNP conjugates can be versatile for any AMO and cell type.

Maternal exposure to fenarimol promotes reproductive performance in mouse offspring.

Although fenarimol is a widely used chlorinated fungicide applied to fruits and vegetables and is a suspected endocrine disrupter, transgenerational studies of low doses of fenarimol exposure are not currently available. The aims of this study are to address the effect of maternal exposure to low doses of fenarimol on the reproductive performance of offspring and to investigate the expression changes of genes associated with this effect. Pregnant mice were orally exposed to low doses (0, 2, 20, and 200 µg/kg body weight) of fenarimol during gestational and lactational periods, and their offspring were assessed. The body and organ weights and anogenital distance (AGD) of mice offspring (F1) maternally exposed to fenarimol were determined, and the reproductive performances of these mice were assessed by mating and ovarian follicular and sperm analyses. Fenarimol-exposed F1 mice had shortened AGDs, increased body weight with altered organ weights, increased number of pups, increased number of ovarian follicles, and enhanced sperm quality. Microarray data showed 82 upregulated and 743 downregulated genes in the ovaries of fenarimol-exposed mice, in which Cyp17a1, Cyp19a1, and ERß were upregulated. In addition, Nobox, a pivotal gene required for proper folliculogenesis, was significantly increased in the ovaries of F1 mice. In conclusion, maternal exposure to fenarimol promotes normal reproductive function in female mouse offspring by increasing the expression levels of genes crucial for ovarian folliculogenesis, identifying fenarimol as a chemical that stimulates reproductive performance. Thus, consumption of fenarimol-contaminated diets by mothers may possibly alter normal reproductive function of offspring in humans and wildlife.

Maternal exposure to benzo[b]fluoranthene disturbs reproductive performance in male offspring mice.

Polycyclic aromatic hydrocarbons (PAHs) are a large family of environmentally prevalent toxic compounds generated from the combustion of organic materials and diesel exhaust. Humans and wild animals are exposed to PAHs mostly through dietary intake of contaminated food. Benzo[b]fluoranthene (B[b]F) is a common constituent of PAH complexes present in diverse types of food. B[b]F has been found in human milk, raising the demand for the need for risk assessment of offspring after maternal exposure to B[b]F. In the present study, pregnant mice were orally exposed to low doses (2-2000µg/kg body weight) of B[b]F during gestational and lactational periods, and their male offspring were assessed. Maternal B[b]F exposure disturbed normal sperm function in F1 offspring. To understand the molecular and cellular mechanisms by which the perinatal exposure to B[b]F decreased sperm quality, the testes of young adult F1 mice were examined for changes in expression of steroidogenesis-related and testicular apoptosis mediators and found that aryl hydrocarbon receptor, estrogen receptor α, and a set of proapoptotic proteins including Bax, Noxa, Bad, and Bim were significantly upregulated. Therefore, the current transgenerational animal study implies that consumption of PAH-contaminated diets by mothers may possibly influence their offspring to cause dysfunctional male reproductive function in humans.

Epistasis between FSHR and CYP19A1 polymorphisms is associated with premature ovarian failure.

Follicle-stimulating hormone secreted from the pituitary gland plays a key role in human reproduction and regulates estrogen production by acting on the regulatory region of CYP19A1. We observed a significant association between premature ovarian failure and the combined genetic effect of single nucleotide polymorphism (SNP) rs4646 (CA+AA) in the 3' untranslated region of CYP19A1 and the missense FSHR SNP rs6166 (AG+GG) genotype (odds ratio 5.42, 95% confidence interval 1.96-14.98), and we identified a significant association between premature ovarian failure and the combined genetic effect of the FSHR missense SNP rs6166 (AA) and the rs4646-rs10046 haplotype (C-T)+(C-C) (odds ratio 5.47, 95% confidence interval 2.03-14.75), suggesting that two biochemical pathways may be involved in the regulation of folliculogenesis.

Absence of a FOXL2 mutation (402C→G) in the blood of adult-type granulosa cell tumor patients possessing the FOXL2 mutation.

Recently, a new mutation in FOXL2, c.402C→G leading to a p.C134W change, was reported to be found in 97% of adult-type ovarian granulosa cell tumors (GCTs) tested. In the current study, we compared the FOXL2 sequences of genomic DNA isolated from both GCT and blood. Although the GCTs of patients possessed the FOXL2 mutation, their FOXL2 nucleotide sequences of genomic DNA isolated from matching blood samples lacked the 402C→G mutation. Therefore, we confirmed that the nucleotide alteration of FOXL2 is due to a somatic mutation and demonstrated that sequencing of blood DNA for the detection of the FOXL2 mutation is not a useful method for the diagnosis of GCT.

Human cord blood-derived endothelial progenitor cells and their conditioned media exhibit therapeutic equivalence for diabetic wound healing.

Transplantation of human cord blood-derived endothelial progenitor cells (EPCs) is reported to contribute to neovascularization in various ischemic diseases. However, the possible beneficial role and underlying mechanisms in diabetes-impaired wound healing have been less well characterized. In this study, EPC transplantation stimulated keratinocyte and fibroblast proliferation substantially as early as 3 days after injury, leading to significantly accelerated wound closure in streptozotocin-induced diabetic nude mice, compared to PBS control. RT-PCR analysis showed that EPCs secreted various wound healing-related growth factors. Among them, keratinocyte growth factor and platelet-derived growth factor were highly expressed in the EPCs and were present at substantial levels in the EPC-injected dermal tissue. Using EPC-conditioned medium (CM), we found that paracrine factors from EPCs directly exerted mitogenic and chemotactic effects on keratinocytes and fibroblasts. Moreover, injection of EPC-CM alone into the same diabetic wound mice promoted wound healing and increased neovascularization to a similar extent as achieved with EPC transplantation. These results indicate that the beneficial effect of EPC transplantation on diabetic wounds was mainly achieved by their direct paracrine action on keratinocytes, fibroblasts, and endothelial cells, rather than through their physical engraftment into host tissues (vasculogenesis). In addition, EPC-CM was shown to be therapeutically equivalent to EPCs, at least for the treatment of diabetic dermal wounds, suggesting that conditioned medium may serve as a novel therapeutic option that is free from allograft-associated immune rejection concern.

The oocyte-specific transcription factor, Nobox, regulates the expression of Pad6, a peptidylarginine deiminase in the oocyte.

Nobox is an oocyte-specific transcriptional regulator. Nobox deficiency disrupts early folliculogenesis and the expression of oocyte-specific genes in mice. In the present study, we found that peptidylarginine deiminase 6 (Pad6) was downregulated in Nobox-null ovaries. Pad6 is preferentially expressed in oocytes and its transcript is detectable at embryonic day 16.5. In addition, we identified one Nobox DNA-binding element (NBE) within the mouse Pad6 promoter. The NBE includes a core sequence TAATTA. Sequence-specific binding of Nobox to the TAATTA motif was confirmed. Nobox overexpression augmented transcriptional activity of a luciferase reporter driven by mouse Pad6. Our findings indicate that Nobox is a critical regulator that orchestrates oocyte-specific genes such as Pad6 during folliculogenesis.

FOXL2 interacts with steroidogenic factor-1 (SF-1) and represses SF-1-induced CYP17 transcription in granulosa cells.

Mutations in FOXL2 are responsible for blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) type I, in which affected women exhibit premature ovarian failure. FOXL2-null mice showed defects in granulosa cell development during folliculogenesis. We screened a rat ovarian yeast two-hybrid cDNA library to identify FOXL2-interacting proteins and found steroidogenic factor-1 (SF-1). Here, we show that human FOXL2 and SF-1 proteins interact in human granulosa cells and that FOXL2 negatively regulates the transcriptional activation of a steroidogenic enzyme, CYP17, by SF-1. Furthermore, FOXL2 mutants found in blepharophimosis-ptosis-epicanthus inversus syndrome type I patients lost the ability to repress CYP17 induction mediated by SF-1. Chromatin immunoprecipitation and EMSA results further revealed that FOXL2 inhibited the binding of SF-1 to the CYP17 promoter, whereas the FOXL2 mutants failed to block this interaction. Therefore, this study identifies a novel regulatory role for FOXL2 on a key steroidogenic enzyme and provides a possible mechanism by which mutations in FOXL2 disrupt normal ovarian follicle development.

MCL-1ES, a novel variant of MCL-1, associates with MCL-1L and induces mitochondrial cell death.

Myeloid cell leukemia-1 (MCL-1L) is a pro-survival member of the BCL-2 family that promotes cell survival. In this study, we identify a new splicing variant of human MCL-1 that encodes MCL-1ES (extra short). Sequence analysis indicates that this variant results from splicing within the first coding exon of MCL-1 at a non-canonical GC-AG donor-acceptor pair. The deduced sequence of MCL-1ES encodes a protein of 197 amino acids, and the PEST (proline, glutamic acid, serine, and threonine) motifs present in MCL-1L are absent. MCL-1ES interacts with MCL-1L and induces mitochondrial cell death, suggesting that alternative splicing of MCL-1 may control the fate of cells.

IEX-1-induced cell death requires BIM and is modulated by MCL-1.

MCL-1 (myeloid cell leukemia-1) is a distinguished and pivotal member of the pro-survival BCL-2 family of proteins, and we isolated IEX-1 (immediate early response gene X-1) as a MCL-1-interacting protein using the yeast two-hybrid system and confirmed their endogenous association in human cells. The underlying mechanisms by which IEX-1 affects cell survival and death are largely unknown. Ectopic expression of IEX-1-induced caspase-dependent apoptosis in 293T cells, and the response was significantly modulated by changes in the MCL-1 expression level in cells. Forced expression of IEX-1 was unable to induce cell death or to perturb mitochondrial membrane potential in BIM-depleted cells. Additionally, knockouts of NOXA or PUMA did not affect the activities of IEX-1, indicating that the pro-death action of IEX-1 specifically requires BIM. Our findings provide insight into a new regulatory circuit that controls cell death and survival by the coordinated action of MCL-1, IEX-1, and BIM.

HIP1R interacts with a member of Bcl-2 family, BCL2L10, and induces BAK-dependent cell death.

The Bcl-2 family members are evolutionally conserved and crucial regulators of apoptosis. BCL2L10 (human Diva or BCL-B) is a member of the Bcl-2 family that has contradictory functions in apoptosis. In the present study, we identified the Huntington-interacting protein 1-related (HIP1R) protein following a search for Diva-interacting proteins using the yeast two-hybrid system. HIP1R is a multi-domain protein that regulates the clathrin-mediated endocytic machinery and actin assembly in cells. Interaction of endogenous proteins of BCL2L10 and HIP1R in 293T cells was determined by immunoprecipitation, and their direct association was confirmed by the Far-Western analysis. The deletion of both the AP180-homology (ANTH) and F-actin-binding the talin-HIP1/R/Sla2p actin-tethering C-terminal homology (THATCH) domains of HIP1R greatly compromised its binding ability to BCL2L10. Ectopic expression of HIP1R resulted in moderate cell death of 293T cells in conjunction with the dissipation of mitochondrial membrane potential and caspase 9 activation. A member of proapoptotic Bcl-2 family, BAK, was required for HIP1R to induce cell death, while BAX was dispensable. In addition, BCL2L10 was associated with endogenous caspase 9, and their binding was augmented by HIP1R overexpression. Thus, this study provided the previously unknown function of HIP1R involved in the intrinsic cell death pathway and further explored possible mechanisms by which HIP1R induces cell death.

Increased expression of the testicular estrogen receptor alpha in adult mice exposed to low doses of methiocarb.

Methiocarb is a widely used carbamate pesticide and a suspected endocrine disrupter. The objective of this study was to examine the in vivo effects of methiocarb at low doses on testicular expression of steroid receptors, spermatogenesis and sperm quality in adult mice. Eighteen-week-old DBA/2 males were treated with daily intraperitoneal injection of methiocarb (0, 0.03, 0.3, 1.0 or 3.0 microg kg(-1) of body weight) for 20 days. Kidney and liver weights were significantly increased in the 1.0 or 3.0 microg kg(-1) treatment groups (P < 0.05). The testicular expression of estrogen receptor alpha (ERalpha) was significantly increased in mice treated with methiocarb as confirmed by Western blot analysis. The sperm production and sperm quality of the methiocarb-exposed mice were not significantly altered as determined using a computer-assisted sperm analysis system. Therefore, these results demonstrate, that although the exposure to methiocarb at low doses alters testicular ERalpha expression in adult mice, both sperm production and quality remain unaffected.