Peroxisome proliferator-activated receptor gamma (PPARγ) is one of the most extensively studied ligand-inducible transcription factors (TFs), able to modulate its transcriptional activity through conformational changes. It is of particular interest because of its pleiotropic functions: it plays a crucial role in the expression of key genes involved in adipogenesis, lipid and glucid metabolism, atherosclerosis, inflammation, and cancer. Its protein isoforms, the wide number of PPARγtarget genes, ligands, and coregulators contribute to determine the complexity of its function. In addition, the presence of genetic variants is likely to affect expression levels of target genes although the impact of PPARG gene variations on the expression of target genes is not fully understood. The introduction of massively parallel sequencing platforms—in the Next Generation Sequencing (NGS) era—has revolutionized the way of investigating the genetic causes of inherited diseases. In this context, DNA-Seq for identifying—within both coding and regulatory regions of PPARG gene—novel nucleotide variations and haplotypes associated to human diseases, ChIP-Seq for defining a PPARγbinding map, and RNA-Seq for unraveling the wide and intricate gene pathways regulated by PPARG, represent incredible steps toward the understanding of PPARγin health and disease.
Thyroid hormones are normally involved in glycaemic control, but their excess can lead to altered glucose metabolism and insulin resistance (IR). Since hyperthyroidism-linked increase in ROS results in tissue oxidative stress that is considered a hallmark of conditions leading to IR, it is conceivable a role of ROS in the onset of IR in hyperthyroidism. To verify this hypothesis, we evaluated the effects of vitamin E on thyroid hormone-induced oxidative damage, insulin resistance, and on gene expression of key molecules involved in IR in the rat liver. The factors involved in oxidative damage, namely the total content of ROS, the mitochondrial production of ROS, the activity of antioxidant enzymes, the in vitro susceptibility to oxidative stress, have been correlated to insulin resistance indices, such as insulin activation of hepatic Akt and plasma level of glucose, insulin and HOMA index. Our results indicate that increased levels of oxidative damage ROS content and production and susceptibility to oxidative damage, parallel increased fasting plasma level of glucose and insulin, reduced activation of Akt and increased activation of JNK. This last result suggests a role for JNK in the insulin resistance induced by hyperthyroidism. Furthermore, the variation of the genes Pparg, Ppara, Cd36 and Slc2a2 could explain, at least in part, the observed metabolic phenotypes.
The growing incidence of diabetes mellitus worldwide implies the increasing prevalence of several related macro- (e.g., hypertension and atherosclerosis) and micro-vascular (e.g., nephropathy and retinopathy) complications. Notably, diabetic retinopathy (DR) is the leading cause of blindness in older diabetic patients and can occur with different degrees of severity. Chronic hyperglycemia is the main determinant of the functional damage of retinal cells. The oxidative stress, inflammatory factors and vascular endothelial growth factor signaling have been widely reported as contributors of DR onset and progression, and an emerging role has been described for different classes of non-coding RNA, including several long non-coding RNAs (lncRNAs). Here, we report the main results of all research articles (i.e., 150) listed on PubMed database from 2014 to 2022 regarding the putative role of lncRNAs in DR, including small nucleolar RNA host genes (SNHGs). Particularly, in this review we describe all lncRNAs and SNHGs with altered expression in DR and related contexts, discussing their association with DR outcomes, their mechanism of action related to DR, the molecular/functional effects, as well as the biological and experimental contexts. Thus, herein we provide an overview of the current state of knowledge regarding the putative involvement of 50 lncRNAs and SNHGs in the pathogenesis of DR, highlighting their potential as therapeutic targets or biomarkers for improving the clinical management of DR.
// Maria Rosaria Ambrosio 1, * , Vittoria D'Esposito 1, * , Valerio Costa 2 , Domenico Liguoro 1 , Francesca Collina 3 , Monica Cantile 3 , Nella Prevete 1 , Carmela Passaro 1 , Giusy Mosca 1 , Michelino De Laurentiis 4 , Maurizio Di Bonito 3 , Gerardo Botti 3 , Renato Franco 5 , Francesco Beguinot 1 , Alfredo Ciccodicola 2, 6 and Pietro Formisano 1 1 Department of Translational Medicine, University of Naples "Federico II" & URT "Genomic of Diabetes" of Institute of Experimental Endocrinology and Oncology "G. Salvatore", National Council of Research (CNR), Naples 80131, Italy 2 Institute of Genetic and Biophysics "A. Buzzati-Traverso", CNR, Naples 80131, Italy 3 Pathology Unit, National Cancer Institute "G. Pascale Foundation", Naples 80131, Italy 4 Department of Breast Surgery and Cancer Prevention, National Cancer Institute "G. Pascale Foundation", Naples 80131, Italy 5 Pathology Unit, Università degli Studi della Campania "Luigi Vanvitelli", Naples 80138, Italy 6 Department of Science and Technology, University of Naples "Parthenope", Naples 80131, Italy * These authors have equally contributed to this work Correspondence to: Pietro Formisano, email: fpietro@unina.it Keywords: breast cancer; tamoxifen; glucose; adipose tissue; connective tissue growth factor Received: April 21, 2017 Accepted: July 25, 2017 Published: November 20, 2017 ABSTRACT Type 2 diabetes and obesity are negative prognostic factors in patients with breast cancer (BC). We found that sensitivity to tamoxifen was reduced by 2-fold by 25 mM glucose (High Glucose; HG) compared to 5.5 mM glucose (Low Glucose; LG) in MCF7 BC cells. Shifting from HG to LG ameliorated MCF7 cell responsiveness to tamoxifen. RNA-Sequencing of MCF7 BC cells revealed that cell cycle-related genes were mainly affected by glucose. Connective Tissue Growth Factor (CTGF) was identified as a glucose-induced modulator of cell sensitivity to tamoxifen. Co-culturing MCF7 cells with human adipocytes exposed to HG, enhanced CTGF mRNA levels and reduced tamoxifen responsiveness of BC cells. Inhibition of adipocyte-released IL8 reverted these effects. Interestingly, CTGF immuno-detection in bioptic specimens from women with estrogen receptor positive (ER + ) BC correlated with hormone therapy resistance, distant metastases, reduced overall and disease-free survival. Thus, glucose affects tamoxifen responsiveness directly modulating CTGF in BC cells, and indirectly promoting IL8 release by adipocytes.
Neurodegenerative disorders and cancer are severe diseases threatening human health. The glaring differences between neurons and cancer cells mask the processes involved in their pathogenesis. Defects in cell cycle, DNA repair and cell differentiation can determine unlimited proliferation in cancer, or conversely, compromise neuronal plasticity, leading to cell death and neurodegeneration. Alteration in regulatory networks affecting gene expression contribute to human diseases' onset, including neurodegenerative disorders, and deregulation of non-coding RNAs - particularly microRNAs - is supposed to have a significant impact. Recently, competitive endogenous RNAs - acting as sponges - have been identified in cancer, indicating a new and intricate regulatory network. Given that neurodegenerative disorders and cancer share altered genes and pathways, and considering the emerging role of microRNAs in neurogenesis, we hypothesize competitive endogenous RNAs may be implicated in neurodegenerative diseases. Here we propose, and computationally predict, such regulatory mechanism may be shared between the diseases. It is predictable that similar regulation occurs in other complex diseases, and further investigation is needed.
Hybridization- and tag-based technologies have been successfully used in Down syndrome to identify genes involved in various aspects of the pathogenesis. However, these technologies suffer from several limits and drawbacks and, to date, information about rare, even though relevant, RNA species such as long and small non-coding RNAs, is completely missing. Indeed, none of published works has still described the whole transcriptional landscape of Down syndrome. Although the recent advances in high-throughput RNA sequencing have revealed the complexity of transcriptomes, most of them rely on polyA enrichment protocols, able to detect only a small fraction of total RNA content. On the opposite end, massive-scale RNA sequencing on rRNA-depleted samples allows the survey of the complete set of coding and non-coding RNA species, now emerging as novel contributors to pathogenic mechanisms. Hence, in this work we analysed for the first time the complete transcriptome of human trisomic endothelial progenitor cells to an unprecedented level of resolution and sensitivity by RNA-sequencing. Our analysis allowed us to detect differential expression of even low expressed genes crucial for the pathogenesis, to disclose novel regions of active transcription outside yet annotated loci, and to investigate a plethora of non-polyadenilated long as well as short non coding RNAs. Novel splice isoforms for a large subset of crucial genes, and novel extended untranslated regions for known genes—possibly novel miRNA targets or regulatory sites for gene transcription—were also identified in this study. Coupling the rRNA depletion of samples, followed by high-throughput RNA-sequencing, to the easy availability of these cells renders this approach very feasible for transcriptome studies, offering the possibility of investigating in-depth blood-related pathological features of Down syndrome, as well as other genetic disorders.
An established hallmark of cancer cells is metabolic reprogramming, largely consisting in the exacerbated glucose uptake. Adipocytes in the tumor microenvironment contribute toward breast cancer (BC) progression and are highly responsive to metabolic fluctuations. Metabolic conditions characterizing obesity and/or diabetes associate with increased BC incidence and mortality. To explore BC-adipocytes interaction and define the impact of glucose in such dialogue, Mammary Adipose-derived Mesenchymal Stem Cells (MAd-MSCs) were differentiated into adipocytes and co-cultured with ER+ BC cells while exposed to glucose concentration resembling hyperglycemia or normoglycemia in humans (25mM or 5.5mM). The transcriptome of both cell types in co-culture as in mono-culture was profiled by RNA-Seq to define the impact of adipocytes on BC cells and viceversa (i), the action of glucose on BC cells, adipocytes (ii) and their crosstalk (iii). Noteworthy, we provided evidence that co-culture with adipocytes in a glucose-rich environment determined a re-program of BC cell transcriptome driving lipid accumulation, a hallmark of BC aggressiveness, promoting stem-like properties and reducing Tamoxifen responsiveness. Moreover, our data point out to a transcriptional effect through which BC cells induce adipocytes de-lipidation, paralleled by pluripotency gain, as source of lipids when glucose lowering occurs. Thus, modulating plasticity of peri-tumoral adipocytes may represent a key point for halting BC progression in metabolically unbalanced patients.
Peroxisome proliferator-activated receptor gamma polymorphisms have been widely associated with type 2 diabetes, although their role in the pathogenesis of vascular complications is not yet demonstrated. In this study, a cohort of 211 type 2 diabetes, 205 obese, and 254 control individuals was genotyped for Pro12Ala, C1431T, C-2821T polymorphisms, and for a newly identified polymorphism (A-2819G). The above-mentioned polymorphisms were analyzed by gene-specific PCR and direct sequencing of all samples. A significant difference was found for -2819G frequency when patients with type 2 diabetes-particularly diabetic women with the proliferative retinopathy-were compared with healthy control individuals. In conclusion, we identified a novel polymorphism, A-2819G, in PPARG gene, and we found it to be associated with type 2 diabetes and proliferative retinopathy in diabetic females. In the analyzed population, this variant represents a genetic risk factor for developing the diabetic retinopathy, whereas Pro12Ala and C1431T do not.
