Iron-responsive miR-485-3p regulates cellular iron homeostasis by targeting ferroportin.

Ferroportin (FPN) is the only known cellular iron exporter in mammalian cells and plays a critical role in the maintenance of both cellular and systemic iron balance. During iron deprivation, the translation of FPN is repressed by iron regulatory proteins (IRPs), which bind to the 5' untranslated region (UTR), to reduce iron export and preserve cellular iron. Here, we report a novel iron-responsive mechanism for the post-transcriptional regulation of FPN, mediated by miR-485-3p, which is induced during iron deficiency and represses FPN expression by directly targeting the FPN 3'UTR. The overexpression of miR-485-3p represses FPN expression and leads to increased cellular ferritin levels, consistent with increased cellular iron. Conversely, both inhibition of miR-485-3p activity and mutation of the miR-485-3p target sites on the FPN 3'UTR are able to relieve FPN repression and lead to decreased cellular iron levels. Together, these findings support a model that includes both IRPs and microRNAs as iron-responsive post-transcriptional regulators of FPN. The involvement of microRNA in the iron-responsive regulation of FPN offers additional stability and fine-tuning of iron homeostasis within different cellular contexts. MiR-485-3p-mediated repression of FPN may also offer a novel potential therapeutic mechanism for circumventing hepcidin-resistant mechanisms responsible for some iron overload diseases.

A comprehensive joint analysis of the long and short RNA transcriptomes of human erythrocytes.

BACKGROUND: Human erythrocytes are terminally differentiated, anucleate cells long thought to lack RNAs. However, previous studies have shown the persistence of many small-sized RNAs in erythrocytes. To comprehensively define the erythrocyte transcriptome, we used high-throughput sequencing to identify both short (18-24 nt) and long (>200 nt) RNAs in mature erythrocytes. RESULTS: Analysis of the short RNA transcriptome with miRDeep identified 287 known and 72 putative novel microRNAs. Unexpectedly, we also uncover an extensive repertoire of long erythrocyte RNAs that encode many proteins critical for erythrocyte differentiation and function. Additionally, the erythrocyte long RNA transcriptome is significantly enriched in the erythroid progenitor transcriptome. Joint analysis of both short and long RNAs identified several loci with co-expression of both microRNAs and long RNAs spanning microRNA precursor regions. Within the miR-144/451 locus previously implicated in erythroid development, we observed unique co-expression of several primate-specific noncoding RNAs, including a lncRNA, and miR-4732-5p/-3p. We show that miR-4732-3p targets both SMAD2 and SMAD4, two critical components of the TGF-ß pathway implicated in erythropoiesis. Furthermore, miR-4732-3p represses SMAD2/4-dependent TGF-ß signaling, thereby promoting cell proliferation during erythroid differentiation. CONCLUSIONS: Our study presents the most extensive profiling of erythrocyte RNAs to date, and describes primate-specific interactions between the key modulator miR-4732-3p and TGF-ß signaling during human erythropoiesis.

Epigenetic regulation of COL15A1 in smooth muscle cell replicative aging and atherosclerosis.

Smooth muscle cell (SMC) proliferation is a hallmark of vascular injury and disease. Global hypomethylation occurs during SMC proliferation in culture and in vivo during neointimal formation. Regardless of the programmed or stochastic nature of hypomethylation, identifying these changes is important in understanding vascular disease, as maintenance of a cells' epigenetic profile is essential for maintaining cellular phenotype. Global hypomethylation of proliferating aortic SMCs and concomitant decrease of DNMT1 expression were identified in culture during passage. An epigenome screen identified regions of the genome that were hypomethylated during proliferation and a region containing Collagen, type XV, alpha 1 (COL15A1) was selected by 'genomic convergence' for characterization. COL15A1 transcript and protein levels increased with passage-dependent decreases in DNA methylation and the transcript was sensitive to treatment with 5-Aza-2'-deoxycytidine, suggesting DNA methylation-mediated gene expression. Phenotypically, knockdown of COL15A1 increased SMC migration and decreased proliferation and Col15a1 expression was induced in an atherosclerotic lesion and localized to the atherosclerotic cap. A sequence variant in COL15A1 that is significantly associated with atherosclerosis (rs4142986, P = 0.017, OR = 1.434) was methylated and methylation of the risk allele correlated with decreased gene expression and increased atherosclerosis in human aorta. In summary, hypomethylation of COL15A1 occurs during SMC proliferation and the consequent increased gene expression may impact SMC phenotype and atherosclerosis formation. Hypomethylated genes, such as COL15A1, provide evidence for concomitant epigenetic regulation and genetic susceptibility, and define a class of causal targets that sit at the intersection of genetic and epigenetic predisposition in the etiology of complex disease.

Atezolizumab with enzalutamide versus enzalutamide alone in metastatic castration-resistant prostate cancer: a randomized phase 3 trial.

Early clinical data indicate that some patients with castration-resistant prostate cancer may benefit from program death ligand-1 (PD-L1) inhibition, especially with enzalutamide. The IMbassador250 trial (no. NCT03016312) enrolled 759 men with metastatic castration-resistant prostate cancer whose disease progressed on abiraterone. The addition of atezolizumab to enzalutamide in an open-label randomized trial did not meet the primary endpoint of improved overall survival in unselected patients (stratified hazard ratio 1.12, 95% confidence interval (0.91, 1.37), P = 0.28), despite an acceptable safety profile. In archival tumor samples, prostate tumors showed comparatively low expression of key immune biomarkers. DNA damage-response alterations, phosphatase and tensin homolog status and PD-L1 expression levels were similar between hormone-sensitive and castration-resistant prostate cancers. In planned biomarker analysis, longer progression-free survival was seen with atezolizumab in patients with high PD-L1 IC2/3, CD8 expression and established immune gene signatures. Exploratory analysis linked progression-free survival in the atezolizumab arm with immune genes such as CXCL9 and TAP1, together with other potentially relevant biomarkers including phosphatase and tensin homolog alterations. Together these data indicate that the expected biology associated with response to immune checkpoint inhibitors is present in prostate cancer, albeit in fewer patients. Careful patient selection may be required for immune checkpoint inhibitors to identify subgroups of patients who may benefit from this treatment approach.

Genetic and functional association of FAM5C with myocardial infarction.

BACKGROUND: We previously identified a 40 Mb region of linkage on chromosome 1q in our early onset coronary artery disease (CAD) genome-wide linkage scan (GENECARD) with modest evidence for linkage (n = 420, LOD 0.95). When the data are stratified by acute coronary syndrome (ACS), this modest maximum in the overall group became a well-defined LOD peak (maximum LOD of 2.17, D1S1589/D1S518). This peak overlaps a recently identified inflammatory biomarker (MCP-1) linkage region from the Framingham Heart Study (maximum LOD of 4.27, D1S1589) and a region of linkage to metabolic syndrome from the IRAS study (maximum LOD of 2.59, D1S1589/D1S518). The overlap of genetic screens in independent data sets provides evidence for the existence of a gene or genes for CAD in this region. METHODS: A peak-wide association screen (457 SNPs) was conducted of a region 1 LOD score down from the peak marker (168-198 Mb) in a linkage peak for acute coronary syndrome (ACS) on chromosome 1, within a family-based early onset coronary artery disease (CAD) sample (GENECARD). RESULTS: Polymorphisms were identified within the 'family with sequence similarity 5, member C' gene (FAM5C) that show genetic linkage to and are associated with myocardial infarction (MI) in GENECARD. The association was confirmed in an independent CAD case-control sample (CATHGEN) and strong association with MI was identified with single nucleotide polymorphisms (SNPs) in the 3' end of FAM5C. FAM5C genotypes were also correlated with expression of the gene in human aorta. Expression levels of FAM5C decreased with increasing passage of proliferating aortic smooth muscle cells (SMC) suggesting a role for this molecule in smooth muscle cell proliferation and senescence. CONCLUSION: These data implicate FAM5C alleles in the risk of myocardial infarction and suggest further functional studies of FAM5C are required to identify the gene's contribution to atherosclerosis.

Phase 1 Study of a Sulforaphane-Containing Broccoli Sprout Homogenate for Sickle Cell Disease.

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy worldwide. Our previous results indicate that the reduced oxidative stress capacity of sickle erythrocytes may be caused by decreased expression of NRF2 (Nuclear factor (erythroid-derived 2)-like 2), an oxidative stress regulator. We found that activation of NRF2 with sulforaphane (SFN) in erythroid progenitors significantly increased the expression of NRF2 targets HMOX1, NQO1, and HBG1 (subunit of fetal hemoglobin) in a dose-dependent manner. Therefore, we hypothesized that NRF2 activation with SFN may offer therapeutic benefits for SCD patients by restoring oxidative capacity and increasing fetal hemoglobin concentration. To test this hypothesis, we performed a Phase 1, open-label, dose-escalation study of SFN, contained in a broccoli sprout homogenate (BSH) that naturally contains SFN, in adults with SCD. The primary and secondary study endpoints were safety and physiological response to NRF2 activation, respectively. We found that BSH was well tolerated, and the few adverse events that occurred during the trial were not likely related to BSH consumption. We observed an increase in the mean relative whole blood mRNA levels for the NRF2 target HMOX1 (p = 0.02) on the last day of BSH treatment, compared to pre-treatment. We also observed a trend toward increased mean relative mRNA levels of the NRF2 target HBG1 (p = 0.10) from baseline to end of treatment, but without significant changes in HbF protein. We conclude that BSH, in the provided doses, is safe in stable SCD patients and may induce changes in gene expression levels. We therefore propose investigation of more potent NRF2 inducers, which may elicit more robust physiological changes and offer clinical benefits to SCD patients. Trial registration: ClinicalTrials.gov NCT01715480.