Ricardo Ramos

Functional interactions in internal translation initiation directed by viral and cellular IRES elements

IP: 54.70.40.11 On: Thu, 25 Oct 2018 04:50:09 Journal of General Virology (2001), 82, 973–984. Printed in Great Britain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Long-range RNA interactions between structural domains of the aphthovirus internal ribosome entry site (IRES).

Internal initiation of translation is promoted by internal ribosome entry site (IRES) cis-acting elements. Using transcripts that correspond to the structural domains of the foot-and-mouth disease virus (FMDV) IRES, we have identified RNA-RNA interactions between separated domains (1-2, 3, 4-5, or HH) of the IRES structure. All the assayed domains were able to interact with the full-length IRES as well as with domain 3, although to a different extent, with the most efficient interactions being those occurring between domains 3 and 4-5, and domains 3 and 1-2. RNA-RNA complexes were stable over 1 h of incubation at 37 degrees C, and depended on Mg2+ and RNA concentration. Neither the antisense domain 1-2 nor tRNA interacted with domain 3, providing experimental evidence of the specificity for the sense strand of the IRES sequence. Additionally, domain 1-2 did not interact with 4-5, leading to the suggestion that domain 3 acts as a scaffold structure where the other domains bind. The thermal disassociation profile of these complexes indicated different strength in these interactions. Whereas 50% of the complexes between domains 3 and 4-5 were destabilized at 45 degrees C, those formed by domain 1-2 and 3 required temperatures higher than 51 degrees C. Efficient self-dimerization of domains 3 and 4-5 was found in the absence of other transcripts. Formation of domain 3 homodimer competed with formation of heterocomplexes with other domains, and conversely, domain 3 homodimers were competed out by the presence of the other domains. RNA interactions were also observed at physiological concentrations of Mg2+ and K1+. The identification of the RNA-RNA complexes reported here provide direct experimental evidence of tertiary interactions within IRES elements.

Long-range RNA-RNA interactions between distant regions of the hepatitis C virus internal ribosome entry site element.

Efficient internal initiation of translation from the hepatitis C virus (HCV) internal ribosome entry site (IRES) requires sequences of domain II, but the precise role of these sequences is still unknown. In this study, the formation of RNA-RNA complexes in the HCV IRES was evaluated. Using transcripts that contain the sequences of the structural HCV IRES domains II, IIIabcd, IIIabc, IV and IIIef-IV, specific long-range interactions between domains II and IV, as well as domains II and IIIabcd, have been found. These interactions were readily detected in a gel mobility-shift assay and required the presence of magnesium ions. A high concentration of nonspecific competitors, an 80 nt fragment of 18S rRNA or poly(I:C), did not interfere with the formation of RNA complexes. Interestingly, an RNA oligonucleotide bearing the sequence of stem-loop IIId interacted with domain II but not with domain IV or IIIef-IV, strongly suggesting that the interaction between domains II and IIIabcd was mediated by the IIId hairpin. Interaction between domains IIIabcd and IV was barely detected, consistent with the result that the apical part of domain III folds independently of the rest of the IRES. Moreover, the addition of stem-loop IIIef sequences to domain IV significantly reduced its ability to interact, which is in agreement with the formation of a compact RNA structure of domain IV with IIIef. The interactions observed in the absence of proteins between domains II and IV as well as stem-loop IIId and domain II may be transient, having a regulatory role in the translation efficiency of the HCV IRES.

miR-9-5p suppresses pro-fibrogenic transformation of fibroblasts and prevents organ fibrosis by targeting NOX4 and TGFBR2

Uncontrolled extracellular matrix (ECM) production by fibroblasts in response to injury contributes to fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Reactive oxygen species (ROS) generation is involved in the pathogenesis of IPF. Transforming growth factor‐β1 (TGF‐β1) stimulates the production of NADPH oxidase 4 (NOX4)‐dependent ROS, promoting lung fibrosis (LF). Dysregulation of microRNAs (miRNAs) has been shown to contribute to LF. To identify miRNAs involved in redox regulation relevant for IPF, we performed arrays in human lung fibroblasts exposed to ROS. miR‐9‐5p was selected as the best candidate and we demonstrate its inhibitory effect on TGF‐β receptor type II (TGFBR2) and NOX4 expression. Increased expression of miR‐9‐5p abrogates TGF‐β1‐dependent myofibroblast phenotypic transformation. In the mouse model of bleomycin‐induced LF, miR‐9‐5p dramatically reduces fibrogenesis and inhibition of miR‐9‐5p and prevents its anti‐fibrotic effect both in vitro and in vivo. In lung specimens from patients with IPF, high levels of miR‐9‐5p are found. In omentum‐derived mesothelial cells (MCs) from patients subjected to peritoneal dialysis (PD), miR‐9‐5p also inhibits mesothelial to myofibroblast transformation. We propose that TGF‐β1 induces miR‐9‐5p expression as a self‐limiting homeostatic response.

IRES elements: features of the RNA structure contributing to their activity

The activity of internal ribosome entry site (IRES) elements depends on their structural organization. We have addressed here the study of conserved structural motifs in the foot-and-mouth disease virus (FMDV) IRES as an example to understand the relationship between RNA structure and function. The features of the RNA structure known to be functionally relevant are discussed in regards to the capacity to modulate interaction of translation initiation factors with the FMDV IRES element. Additionally, the contribution of non-canonical RNA-binding proteins to FMDV IRES organization as well as stimulation of its activity by other mRNA regions is discussed.

Genes associated with metabolic syndrome predict disease-free survival in stage II colorectal cancer patients. A novel link between metabolic dysregulation and colorectal cancer

Studies have recently suggested that metabolic syndrome and its components increase the risk of colorectal cancer. Both diseases are increasing in most countries, and the genetic association between them has not been fully elucidated. The objective of this study was to assess the association between genetic risk factors of metabolic syndrome or related conditions (obesity, hyperlipidaemia, diabetes mellitus type 2) and clinical outcome in stage II colorectal cancer patients. Expression levels of several genes related to metabolic syndrome and associated alterations were analysed by real‐time qPCR in two equivalent but independent sets of stage II colorectal cancer patients. Using logistic regression models and cross‐validation analysis with all tumour samples, we developed a metabolic syndrome‐related gene expression profile to predict clinical outcome in stage II colorectal cancer patients. The results showed that a gene expression profile constituted by genes previously related to metabolic syndrome was significantly associated with clinical outcome of stage II colorectal cancer patients. This metabolic profile was able to identify patients with a low risk and high risk of relapse. Its predictive value was validated using an independent set of stage II colorectal cancer patients. The identification of a set of genes related to metabolic syndrome that predict survival in intermediate‐stage colorectal cancer patients allows delineation of a high‐risk group that may benefit from adjuvant therapy and avoid the toxic and unnecessary chemotherapy in patients classified as low risk. Our results also confirm the linkage between metabolic disorder and colorectal cancer and suggest the potential for cancer prevention and/or treatment by targeting these genes.

Prognostic value of peripheral blood mononuclear cell-associated HIV-1 DNA for virological outcome in asymptomatic HIV-1 chronic infection

BACKGROUND Studies in primary HIV-1 infection and advanced HIV-1 disease have demonstrated that HIV-1 DNA associated with peripheral blood mononuclear cells (PBMC HIV-1 DNA) has predictive value for disease progression. OBJECTIVES To analyse in asymptomatic HIV-1 chronic infection the predictive value of PBMC HIV-1 DNA for virological failure. STUDY DESIGN In 115 individuals who had previously participated in study STIR-2102, we retrospectively analysed the PBMC HIV-1 DNA by quantitative real-time PCR. Antiretroviral naïve patients (baseline pre-ART) received 6 weeks of ART prior to randomisation (baseline post-ART). The predictive value of PBMC HIV-1 DNA, HIV-1 RNA in plasma and CD4+ T cells, at baselines pre-ART and post-ART, was determined by Kaplan-Meier and Proportional Hazards Regression analyses. RESULTS At baseline post-ART, 82% of patients showed suppression of HIV-1 RNA, however they maintained significant amounts of HIV-1 DNA (geometric mean: 690 copies/10(6) PBMC). Pre-ART and post-ART levels of HIV-1 DNA and pre-ART levels of HIV-1 RNA showed predictive value (Log-Rank test: p<0.001, p<0.001, p=0.003, respectively). In a multivariate model post-ART PBMC HIV-1 DNA was the stronger predictive variable (adjusted HR, 2.51 [95% CI, 1.33-4.73, p=0.004]) independently of HIV-1 RNA (HR 1.74 [95% CI, 1.16-2.61, p=0.007]). CONCLUSIONS PBMC HIV-1 DNA is an effective prognostic marker for virological outcome in individuals with asymptomatic HIV-1 chronic infection.

Expression of Early Growth Response Gene-2 and Regulated Cytokines Correlates with Recovery from Guillain–Barré Syndrome

Guillain–Barré syndrome (GBS) is an immune-mediated peripheral neuropathy. The goal of this research was the identification of biomarkers associated with recovery from GBS. In this study, we compared the transcriptome of PBMCs from a GBS patient and her healthy twin to discover possible correlates of disease progression and recovery. The study was then extended using GBS and spinal cord injury unrelated patients with similar medications and healthy individuals. The early growth response gene-2 (EGR2) was upregulated in GBS patients during disease recovery. The results provided evidence for the implication of EGR2 in GBS and suggested a role for EGR2 in the regulation of IL-17, IL-22, IL-28A, and TNF-β cytokines in GBS patients. These results identified biomarkers associated with GBS recovery and suggested that EGR2 overexpression has a pivotal role in the downregulation of cytokines implicated in the pathophysiology of this acute neuropathy.

Dysregulated miRNAs and their pathogenic implications for the neurometabolic disease propionic acidemia

AbstractmiRNome expression profiling was performed in a mouse model of propionic acidemia (PA) and in patients’ plasma samples to investigate the role of miRNAs in the pathophysiology of the disease and to identify novel biomarkers and therapeutic targets. PA is a potentially lethal neurometabolic disease with patients developing neurological deficits and cardiomyopathy in the long-term, among other complications. In the PA mouse liver we identified 14 significantly dysregulated miRNAs. Three selected miRNAs, miR-34a-5p, miR-338-3p and miR-350, were found upregulated in brain and heart tissues. Predicted targets involved in apoptosis, stress-signaling and mitochondrial function, were inversely found down-regulated. Functional analysis with miRNA mimics in cellular models confirmed these findings. miRNA profiling in plasma samples from neonatal PA patients and age-matched control individuals identified a set of differentially expressed miRNAs, several were coincident with those identified in the PA mouse, among them miR-34a-5p and miR-338-3p. These two miRNAs were also found dysregulated in childhood and adult PA patients’ cohorts. Taken together, the results reveal miRNA signatures in PA useful to identify potential biomarkers, to refine the understanding of the molecular mechanisms of this rare disease and, eventually, to improve the management of patients.

P3.01-88 Clinical and Molecular Analysis of Long-Term Survivors with Advanced Non-Small Cell Lung Cancer: A Multicenter Experience in Madrid

expected total cumulative dose received. Objective response rate (CR+PR) in the entire cohort was 66%. Median progression-free survival (PFS) from start of alternate schedule is 17.1 months (95% CI 5.2not reached). 6-month PFS is 65% (95% CI 46%-79%) starting from when alternate schedule of Nivo was begun. We will present updated toxicity and treatment outcomes in the meeting. Conclusion: Nivolumab 240mg administered at q 4 weeks or longer is feasible. Further investigation is needed to optimize patient selection for alternate dosing schedule.