Expression of activating transcription factor 5 (ATF5) is mediated by microRNA-520b-3p under diverse cellular stress in cancer cells

RNA sequencing analysis revealed differentially expressed genes and their functional annotation in porcine longissimus dorsi muscle affected by dietary lysine restriction

The objective of this study was to investigate the effects of dietary lysine restriction on the global gene expression profile of skeletal muscle in growing pigs. Twelve crossbred (Yorkshire × Landrace) barrows (initial BW 22.6 ± 2.04 kg) were randomly assigned to two dietary treatments (LDD: a lysine-deficient diet; LAD: a lysine-adequate diet) according to a completely randomized experiment design (n = 6). After feeding for 8 weeks, skeletal muscle was sampled from the longissimus dorsi of individual pigs. The muscle total RNA was isolated and cDNA libraries were prepared for RNA sequencing (RNA-Seq) analysis. The RNA-Seq data obtained was then analyzed using the CLC Genomics Workbench to identify differentially expressed genes (DEGs). A total of 80 genes (padj ≤ 0.05) were differentially expressed in the longissimus dorsi muscle of the pigs fed LDD vs. LAD, of which 46 genes were downregulated and 34 genes were upregulated. Gene Ontology (GO) analysis of the DEGs (padj ≤ 0.05) for functional annotation identified those GO terms that are mostly associated with the molecular functions of structural molecules and metabolic enzymes (e.g., oxidoreductase and endopeptidase), biological process of acute-phase response, and amino acid metabolism including synthesis and degradation in the extracellular matrix region. Collectively, the results of this study have provided some novel insight regarding the molecular mechanisms of muscle growth that are associated with dietary lysine supply.

Metabolic Pathways in Breast Cancer Reprograming: An Insight to Non-Coding RNAs

Cancer cells reprogram their metabolisms to achieve high energetic requirements and produce precursors that facilitate uncontrolled cell proliferation. Metabolic reprograming involves not only the dysregulation in glucose-metabolizing regulatory enzymes, but also the enzymes engaging in the lipid and amino acid metabolisms. Nevertheless, the underlying regulatory mechanisms of reprograming are not fully understood. Non-coding RNAs (ncRNAs) as functional RNA molecules cannot translate into proteins, but they do play a regulatory role in gene expression. Moreover, ncRNAs have been demonstrated to be implicated in the metabolic modulations in breast cancer (BC) by regulating the metabolic-related enzymes. Here, we will focus on the regulatory involvement of ncRNAs (microRNA, circular RNA and long ncRNA) in BC metabolism, including glucose, lipid and glutamine metabolism. Investigation of this aspect may not only alter the approaches of BC diagnosis and prognosis, but may also open a new avenue in using ncRNA-based therapeutics for BC treatment by targeting different metabolic pathways.

Progression of Type 1 Diabetes: Circulating MicroRNA Expression Profiles Changes from Preclinical to Overt Disease

Objectives

To evaluate the potential biological involvement of miRNA expression in the immune response and beta cell function in T1D.

Methods

We screened 377 serum miRNAs of 110 subjects divided into four groups: healthy individuals (control group) and patients at different stages of T1D progression, from the initial immunological manifestation presenting islet autoantibodies (AbP group) until partial and strong beta cell damage in the recent (recent T1D group) and long-term T1D, with 2 to 5 years of disease (T1D 2-5y group).

Results

The results revealed 69 differentially expressed miRNAs (DEMs) in relation to controls. Several miRNAs were correlated with islet autoantibodies (IA2A, GADA, and Znt8A), age, and C-peptide levels, mainly from AbP, and recent T1D groups pointing these miRNAs as relevant to T1D pathogenesis and progression. Several miRNAs were related to metabolic derangements, inflammatory pathways, and several other autoimmune diseases. Pathway analysis of putative DEM targets revealed an enrichment in pathways related to metabolic syndrome, inflammatory response, apoptosis and insulin signaling pathways, metabolic derangements, and decreased immunomodulation. One of the miRNAs' gene targets was DYRK2 (dual-specificity tyrosine-phosphorylation-regulated kinase 2), which is an autoantigen targeted by an antibody in T1D. ROC curve analysis showed hsa-miR-16 and hsa-miR-200a-3p with AUCs greater than for glucose levels, with discriminating power for T1D prediction greater than glucose levels. Conclusions/Interpretation. Our data suggests a potential influence of DEMs on disease progression from the initial autoimmune lesion up to severe beta cell dysfunction and the role of miRNAs hsa-miR-16 and hsa-miR-200a-3p as biomarkers of T1D progression.

Advancements in Activating Transcription Factor 5 Function in Regulating Cell Stress and Survival

Activating transcription factor 5 (ATF5) belongs to the activating transcription factor/cyclic adenosine monophosphate (cAMP) response element-binding protein family of basic region leucine zipper transcription factors. ATF5 plays an important role in cell stress regulation and is involved in cell differentiation and survival, as well as centrosome maintenance and development. Accumulating evidence demonstrates that ATF5 plays an oncogenic role in cancer by regulating gene expressions involved in tumorigenesis and tumor survival. Recent studies have indicated that ATF5 may also modify the gene expressions involved in other diseases. This review explores in detail the regulation of ATF5 expression and signaling pathways and elucidates the role of ATF5 in cancer biology. Furthermore, an overview of putative therapeutic strategies that can be used for restoring aberrant ATF5 activity in different cancer types is provided.

Human Cytomegalovirus Infection Activates Glioma Activating Transcription Factor 5 via microRNA in a Stress-Induced Manner

Human cytomegalovirus (HCMV) harnesses a cell-specific manner to infect human nervous system cancer cells, establishes a life-long persistent infection without cell death, and modulates signaling pathways associated with cancer. We previously identified that the HCMV immediate-early 2 (IE2-86) protein binds and activates activating transcription factor 5 (ATF5), a survival factor in many tumor cells. In this study, we investigated a new mechanism of stress-induced miRNA regulation at the ATF5 3' UTR under the HCMV infection and other cellular stress conditions. We employed RNA-Seq and in silico analysis to screen stress response gene sets and identify miRNA candidates as potential regulators of ATF5 following HCMV infection. We found that ATF5 and cellular stress response genes were significantly upregulated under HCMV infection and diverse stress conditions. Three downregulated miRNAs were filtrated based on our threshold, and their binding sites for 3' UTR of ATF5 were predicted. Then, luciferase reporter assays were carried out to verify the binding sites for all three miRNA candidates targeting ATF5. However, in vitro validation has shown that miR-134-5p is the only candidate that can reverse the ATF5 protein upregulation under infection and other cell stresses. Additionally, miR-134-5p levels were significantly reduced and inversely related to ATF5 mRNA under HCMV infection. These results provide new evidence that quiescent HCMV infection can trigger a stress response in glioma cells and modulate ATF5 levels by downregulating specific miRNA.