Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production.
A cell-autonomous molecular cascade initiated by AMP-activated protein kinase represses steroidogenesis.
Specimen part, Treatment
View SamplesTestosterone production by Leydig cells is a tightly regulated process requiring synchronized expression of several steroidogenic genes by numerous transcription factors. Myocyte enhancer factor 2 (MEF2) is a transcription factor recently identified in somatic cells of the male gonad. In other tissues, MEF2 is an essential regulator of organogenesis and cell differentiation. So far in the testis, MEF2 was found to regulate Leydig cell steroidogenesis by controlling Nr4a1 and Star gene expression. To expand our understanding of the role of MEF2 in Leydig cells, we performed microarray analyses of MA-10 Leydig cells depleted in MEF2 and results were analyzed using the Partek and IPA softwares. Several genes were differentially expressed in MEF2-depleted Leydig cells and 15 were validated by qPCR. A large number of these genes are known to be involved in fertility, gonad morphology and steroidogenesis and include Pde8a, Por, Ahr, Bmal1, Cyp1a1, Cyp1b1, Map2k1, Tsc22d3, Nr0b2, Smad4, and Star, which were all downregulated in the absence of MEF2. In silico analyses revealed the presence of MEF2 binding sites within the first 2 kb upstream the transcription start site of the Por, Bmal1, and Nr0b2 promoters, which suggests a direct regulation by MEF2. Using transient transfections in MA-10 Leydig cells, siRNA knockdown, and a MEF2-Engrailed dominant negative, we found that MEF2 activates the Por, Bmal1 and Nr0b2 promoters and that this requires an intact MEF2 element. Our results identify novel target genes for MEF2 and define MEF2 as an important regulator of Leydig cell function and male reproduction.
Novel Targets for the Transcription Factors MEF2 in MA-10 Leydig Cells.
Specimen part, Cell line
View SamplesshRNA-mediated ablation of the RING-finger protein TRIM52 from multiple glioblastoma cell lines reduces proliferation and tumorigenesis. To identify gene signatures underlying this phenomenon, transcritional profile of TRIM52 knockdown cells was compared to control cells. Upon TRIM52 ablation, we find 278 differentially regulated genes. Gene ontology analysis reveals that many of the upregulated genes are associated with glycolysis and biosynthetic processes. Overall design: U87MG glioblastoma cells were stably transduced with doxycycline-inducible shRNA constructs targeting TRIM52 (two different shRNAs) or controls (two different non-targeting shRNAs). Knockdown was induced for five days using 2µg/ml doxycycline. shRNA expressing cells were sorted based on shRNA-coupled GFP expression via flow cytometry. mRNA sequening was performed in duplicate per shRNA cell line.
Human tripartite motif protein 52 is required for cell context-dependent proliferation.
Specimen part, Subject
View SamplesThe MYC transcription factor is a master regulator of diverse cancer pathways and somatic cell reprogramming. MYC is a compelling therapeutic target that exhibits cancer-specific cellular effects. Pharmacologic inhibition of MYC function has proven challenging due to its numerous modes of forced expression and the difficulty of disrupting protein-DNA interactions. Here we demonstrate the rapid and potent abrogation of MYC gene transcription by representative small molecule bromodomain inhibitors of the BET family of chromatin adaptors. This transcriptional suppression of MYC was observed in the context of the natural, chromosomally translocated, and amplified gene locus. Inhibition of BET bromodomain-promoter interactions and subsequent reduction of MYC transcript and protein levels resulted in G1 arrest and extensive apoptosis in a variety of leukemia and lymphoma cell lines. Exogenous expression of MYC from an artificial promoter that is resistant to BET regulation significantly protected cells from growth suppression by BET inhibitors and revealed that MYC exerts a direct and tight control of key pro-growth and anti-apoptotic target genes. Transcriptional profiling of two cells after 4 and 8 hours of treatment with BET inhibitor shows that both MYC and its targets are strongly down-regulated. We thus demonstrate that pharmacologic inhibition of MYC is achievable through targeting BET bromodomains, and suggest that such inhibitors may have broad clinical applicability given the widespread pathogenetic role of MYC in cancer.
Targeting MYC dependence in cancer by inhibiting BET bromodomains.
Cell line, Treatment
View SamplesWe obtained single-cell RNA-sequencing (scRNA-seq) profiles of CD14+ monocytes isolated from human peripheral blood at 0, 3 and 6 days after M-CSF stimulation (to differentiate the cells into macrophages) across multiple donors. Integration of single-cell RNA sequencing (scRNA-seq) data from multiple experiments, laboratories, and technologies can uncover biological insights, but current methods for scRNA-seq data integration are limited by a requirement for datasets to derive from functionally similar cells. We use a novel algorithm, Scanorama, to identify and merge the shared cell types among all pairs of datasets and to accurately integrate heterogeneous scRNA-seq datasets. Scanorama is sensitive to subtle temporal changes within the same cell lineage, successfully integrating functionally similar cells across time series data of CD14+ monocytes at different stages of differentiation into macrophages. Scanorama is not only able to differentiate between completely disparate cell types but is also sensitive to subtler transcriptional changes within a cell type due to processes like stimulation. Overall design: scRNA-seq of human CD14+ monocytes at 0, 3, and 6 days after M-CSF stimulation in multiple donors
Efficient integration of heterogeneous single-cell transcriptomes using Scanorama.
Specimen part, Treatment, Subject
View SamplesTargets of Retinoic Acid (RA) and 3,4-didehydroretinoic acid (ddRA) were identified in primary human epidermal keratinocytes grown in the presence of atRA or ddRA for 4 and 24 hours.
The effect of two endogenous retinoids on the mRNA expression profile in human primary keratinocytes, focusing on genes causing autosomal recessive congenital ichthyosis.
Treatment
View SamplesDisruption of N-linked glycosylation has a broad impact on proper glycosylation of nascent glycoproteins in the endoplasmic reticulum, which affect multiple signalling pathways( by changing the stability of membrane proteins or the signalling ability of membrane receptors) and may be responsible of the fibrotic stage associated to CDG type-I.
Fibrotic response in fibroblasts from congenital disorders of glycosylation.
No sample metadata fields
View SamplesExploring the expression profile of ovarian clear cell carcinoma cancer cell subpopulations- derived tumors grown within a murine and a human cellular tissues.
Niche-dependent gene expression profile of intratumoral heterogeneous ovarian cancer stem cell populations.
Specimen part
View SamplesInduced pluripotent stem cell-derived human hepatocyte-like cells (iHeps) could provide a powerful tool for studying the mechanisms underlying human liver development and disease, testing the efficacy and safety of pharmaceuticals across different patients (i.e. personalized medicine), and enabling cell-based therapies in the clinic. However, current in vitro protocols that rely upon growth factors and extracellular matrices (ECM) alone yield iHeps with low levels of liver functions relative to adult primary human hepatocytes (PHHs). Moreover, these low hepatic functions in iHeps are difficult to maintain for prolonged times (weeks to months) in culture. Here, we engineered a micropatterned co-culture (iMPCC) platform in a multi-well format that, in contrast to conventional confluent cultures, significantly enhanced the functional maturation and longevity of iHeps in culture for 4 weeks in vitro when benchmarked against multiple donors of PHHs. In particular, iHeps were micropatterned onto collagen-coated domains of empirically optimized dimensions, surrounded by 3T3-J2 murine embryonic fibroblasts, and then sandwiched with a thin layer of ECM gel (Matrigel). We assessed iHep maturity via global gene expression profiles, hepatic polarity, secretion of albumin and urea, basal CYP450 activities, phase-II conjugation, drug-mediated CYP450 induction, and drug-induced hepatotoxicity. Conclusion: Controlling both homotypic interactions between iHeps and heterotypic interactions with stromal fibroblasts significantly matures iHep functions and maintains them for several weeks in culture. In the future, iMPCCs could prove useful for drug screening, studying molecular mechanisms underlying iHep differentiation, modeling liver diseases, and integration into human-on-a-chip systems being designed to assess multi-organ responses to compounds.
Enhancing the functional maturity of induced pluripotent stem cell-derived human hepatocytes by controlled presentation of cell-cell interactions in vitro.
Specimen part, Subject
View SamplesRacial differences in the pathophysiology of atherothrombosis are poorly understood. We explored the function and transcriptome of platelets in healthy black (n=70) and white (n=84) subjects.
Racial differences in human platelet PAR4 reactivity reflect expression of PCTP and miR-376c.
Specimen part, Race
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