Small-Molecule Hormones: Molecular Mechanisms of Action

Small-molecule hormones play crucial roles in the development and in the maintenance of an adult mammalian organism. On the molecular level, they regulate a plethora of biological pathways. Part of their actions depends on their transcription-regulating properties, exerted by highly specific nuclear receptors which are hormone-dependent transcription factors. Nuclear hormone receptors interact with coactivators, corepressors, basal transcription factors, and other transcription factors in order to modulate the activity of target genes in a manner that is dependent on tissue, age and developmental and pathophysiological states. The biological effect of this mechanism becomes apparent not earlier than 30–60 minutes after hormonal stimulus. In addition, small-molecule hormones modify the function of the cell by a number of nongenomic mechanisms, involving interaction with proteins localized in the plasma membrane, in the cytoplasm, as well as with proteins localized in other cellular membranes and in nonnuclear cellular compartments. The identity of such proteins is still under investigation; however, it seems that extranuclear fractions of nuclear hormone receptors commonly serve this function. A direct interaction of small-molecule hormones with membrane phospholipids and with mRNA is also postulated. In these mechanisms, the reaction to hormonal stimulus appears within seconds or minutes

Interleukin-6 and C-reactive protein, successful aging, and mortality : the PolSenior study

BACKGROUND: In the elderly, chronic low-grade inflammation (inflammaging) is a risk factor for the development of aging-related diseases and frailty. Using data from several thousand Eastern Europeans aged 65 years and older, we investigated whether the serum levels of two proinflammatory factors, interleukin-6 (IL-6) and C-reactive protein (CRP), were associated with physical and cognitive performance, and could predict mortality in successfully aging elderly. RESULTS: IL-6 and CRP levels systematically increased in an age-dependent manner in the entire study group (IL-6: n = 3496 individuals, p < 0.001 and CRP: n = 3632, p = 0.003), and in the subgroup of successfully aging individuals who had never been diagnosed with cardiovascular disease, myocardial infarction, stroke, type 2 diabetes, or cancer, and had a Mini Mental State Examination (MMSE) score ≥24 and a Katz Activities of Daily Living (ADL) score ≥5 (IL-6: n = 1258, p < 0.001 and CRP: n = 1312, p < 0.001). In the subgroup of individuals suffering from aging-related diseases/disability, only IL-6 increased with age (IL-6: n = 2238, p < 0.001 and CRP: n = 2320, p = 0.249). IL-6 and CRP levels were lower in successfully aging individuals than in the remaining study participants (both p < 0.001). Higher IL-6 and CRP levels were associated with poorer physical performance (lower ADL score) and poorer cognitive performance (lower MMSE score) (both p < 0.001). This association remained significant after adjusting for age, gender, BMI, lipids, estimated glomerular filtration rate, and smoking status. Longer survival was associated with lower concentrations of IL-6 and CRP not only in individuals with aging-related diseases/disability (HR = 1.063 per each pg/mL, 95 % CI: 1.052-1.074, p < 0.001 and HR = 1.020 per each mg/L, 95 % CI: 1.015-1.025, p < 0.001, respectively) but also in the successfully aging subgroup (HR = 1.163 per each pg/mL, 95 % CI: 1.128-1.199, p < 0.001 and HR = 1.074 per each mg/L, 95 % CI: 1.047-1.100, p < 0.001, respectively). These associations remained significant after adjusting for age, gender, BMI, lipids and smoking status. The Kaplan-Meier survival curves showed similar results (all p < 0.001). CONCLUSIONS: Both IL-6 and CRP levels were good predictors of physical and cognitive performance and the risk of mortality in both the entire elderly population and in successfully aging individuals

Exploratory data analysis of a clinical study group: Development of a procedure for exploring multidimensional data.

Thorough knowledge of the structure of analyzed data allows to form detailed scientific hypotheses and research questions. The structure of data can be revealed with methods for exploratory data analysis. Due to multitude of available methods, selecting those which will work together well and facilitate data interpretation is not an easy task. In this work we present a well fitted set of tools for a complete exploratory analysis of a clinical dataset and perform a case study analysis on a set of 515 patients. The proposed procedure comprises several steps: 1) robust data normalization, 2) outlier detection with Mahalanobis (MD) and robust Mahalanobis distances (rMD), 3) hierarchical clustering with Ward's algorithm, 4) Principal Component Analysis with biplot vectors. The analyzed set comprised elderly patients that participated in the PolSenior project. Each patient was characterized by over 40 biochemical and socio-geographical attributes. Introductory analysis showed that the case-study dataset comprises two clusters separated along the axis of sex hormone attributes. Further analysis was carried out separately for male and female patients. The most optimal partitioning in the male set resulted in five subgroups. Two of them were related to diseased patients: 1) diabetes and 2) hypogonadism patients. Analysis of the female set suggested that it was more homogeneous than the male dataset. No evidence of pathological patient subgroups was found. In the study we showed that outlier detection with MD and rMD allows not only to identify outliers, but can also assess the heterogeneity of a dataset. The case study proved that our procedure is well suited for identification and visualization of biologically meaningful patient subgroups

Age-related epigenetic drift deregulates SIRT6 expression and affects its downstream genes in human peripheral blood mononuclear cells

Sirtuin 6 (SIRT6) exerts a protective effect on health and extends the lives of model organisms. We, therefore, aimed to clarify whether age-related epigenetic drift is responsible for differences in SIRT6 expression in peripheral blood mononuclear cells (PBMCs) of healthy young (n = 55, mean age 27.5 ± 4.4 years), middle-aged (n = 51, 65.4 ± 3.3 years), and long-lived (n = 51, 93.9 ± 3.6 years) humans. In silico analysis was performed using the STRING network. No age-related differences were observed in the percentage of SIRT6 CpG island methylation. However, the age affected the expression of miR-34a-5p, miR-125a-5p, miR-186-5p, miR-342-5p and miR-766-3p (all p < 0.0001), miR-181-2-3p and Let-7c (both p = 0.0003), and miR-103a-3p (p = 0.0069). A negative association was observed between SIRT6 mRNA and miR-186-5p (rs = −0.25, p = 0.026), and a positive association was observed with miR-34a-5p (rs = 0.31, p = 0.0055) and miR-181a-2-3p (rs = 0.39, p = 0.0002). SIRT6 mRNA also negatively correlated with the expression of TP53 (rs = −0.41, p = 0.0126) and MYC (rs = −0.35, p = 0.0448). Notably, the expression of several miRNAs and genes was similar in young and long-lived groups but different from the middle-aged group. We conclude that age-related epigenetic changes can affect the expression of SIRT6 in PBMCs and, in this way, possibly influence immunosenescence. Moreover, molecular events could differentiate ‘normal’ ageing from that of long-lived individuals

Telomere Length in Elderly Caucasians Weakly Correlates with Blood Cell Counts

Background. Age-related decrease in bone marrow erythropoietic capacity is often accompanied by the telomere length shortening in peripheral white blood cells. However, limited and conflicting data hamper the conclusive opinion regarding this relationship. Therefore, the aim of this study was to assess an association between telomere length and peripheral blood cell count parameters in the Polish elderly population. Material and Methods. The substudy included 1573 of 4981 subjects aged 65 years or over, participants of the population-based PolSenior study. High-molecular-weight DNA was isolated from blood mononuclear cells. Telomere length (TL) was measured by QRT-PCR as abundance of telomere template versus a single gene copy encoding acidic ribosomal phosphoprotein P0. Results. Only white blood count (WBC) was significantly different in TL tertile subgroups in all subjects (P=0.02) and in men (P=0.01), but not in women. Merely in men significant but weak positive correlations were found between TL and WBC (r=0.11, P<0.05) and RBC (r=0.08, P<0.05). The multiple regression analysis models confirmed a weak, independent contribution of TL to both RBC and WBC. Conclusions. In the elderly, telomere shortening limits hematopoiesis capacity to a very limited extent

NGS Reveals Molecular Pathways Affected by Obesity and Weight Loss-Related Changes in miRNA Levels in Adipose Tissue

Both obesity and weight loss may cause molecular changes in adipose tissue. This study aimed to characterize changes in adipose tissue miRNome in order to identify molecular pathways affected by obesity and weight changes. Next generation sequencing (NGS) was applied to identify microRNAs (miRNAs) differentially expressed in 47 samples of visceral (VAT) and subcutaneous (SAT) adipose tissues from normal-weight (N), obese (O) and obese after surgery-induced weight loss (PO) individuals. Subsequently miRNA expression was validated by real-time PCR in 197 adipose tissues and bioinformatics analysis performed to identify molecular pathways affected by obesity-related changes in miRNA expression. NGS identified 344 miRNAs expressed in adipose tissues with ≥5 reads per million. Using &gt;2 and &lt;−2 fold change as cut-offs we showed that the expression of 54 miRNAs differed significantly between VAT-O and SAT-O. Equally, between SAT-O and SAT-N, the expression of 20 miRNAs differed significantly, between SAT-PO and SAT-N the expression of 79 miRNAs differed significantly, and between SAT-PO and SAT-O, the expression of 61 miRNAs differed significantly. Ontological analyses disclosed several molecular pathways regulated by these miRNAs in adipose tissue. NGS-based miRNome analysis characterized changes of the miRNA profile of adipose tissue, which are associated with changes of weight possibly responsible for a differential regulation of molecular pathways in adipose tissue when the individual is obese and after the individual has lost weight

Telomere Length in Elderly Caucasians Weakly Correlates with Blood Cell Counts

Background. Age-related decrease in bone marrow erythropoietic capacity is often accompanied by the telomere length shortening in peripheral white blood cells. However, limited and conflicting data hamper the conclusive opinion regarding this relationship. Therefore, the aim of this study was to assess an association between telomere length and peripheral blood cell count parameters in the Polish elderly population. Material and Methods. The substudy included 1573 of 4981 subjects aged 65 years or over, participants of the population-based PolSenior study. High-molecular-weight DNA was isolated from blood mononuclear cells. Telomere length (TL) was measured by QRT-PCR as abundance of telomere template versus a single gene copy encoding acidic ribosomal phosphoprotein P0. Results. Only white blood count (WBC) was significantly different in TL tertile subgroups in all subjects ( = 0.02) and in men ( = 0.01), but not in women. Merely in men significant but weak positive correlations were found between TL and WBC ( = 0.11, &lt; 0.05) and RBC ( = 0.08, &lt; 0.05). The multiple regression analysis models confirmed a weak, independent contribution of TL to both RBC and WBC. Conclusions. In the elderly, telomere shortening limits hematopoiesis capacity to a very limited extent