Search

Mitochondria uncoupling protein2 (UCP2) expressed ubiquitously is a key molecule of energy metabolism. Insulin-like growth factor-1 (IGF-1) is a hormone, a target molecule of growth hormone (GH) signal pathway, which is also known as the drug "mecasermin" for clinical usages. IGF-1 is seemed to be closely related to metabolic diseases, such as adult GH deficiency. However, there has not been reports depicted possible relationship with each other. So, we sought to elucidate the mechanisms by which expression of UCP2 is regulated by IGF-1 via FOXO1. The findings suggested that three sequences in the consensus UCP2 promoter play complementary functional roles in the functional expression of FOXO1. So, we found that FOXO1 is involved in IGF-1-mediated energy metabolism greater than that of direct action of GH via STAT5. Our findings suggested that IGF-1 was involved in energy metabolism by regulating the expression of UCP2 via the PI3K/Akt/FOXO1 pathway.

Objective The objective of our study was to examine the direct action of insulin-like growth factor-1(IGF-1) signaling on energy homeostasis in myocytes. Design We studied the IGF-1 stimulation of mitochondrial uncoupling protein 3 (UCP3) expression in the HEK 293 derived cell line TSA201, murine C2C12 skeletal muscle myoblasts, and rat L6 skeletal myoblasts. We also investigated the direct effect of IGF-1 on the Insulin/IGF-1 receptor (IGF-1R)/phosphatidylinositol 3 (PI3)-Akt/forkhead box O4 (FOXO4) pathway using a combination of a reporter assay, semi-quantitative polymerase chain reaction, western blotting, and animal experiments. Results We demonstrated that IGF-1 regulates UCP3 expression via phosphorylation of FOXO4, which is a downstream signal transducer of IGF-1. UCP3 expression increased with activated FOXO4 in a dose-dependent manner. We also examined the functional FOXO4 binding site consensus sequences and identified it as the −1922 bp site in the UCP3 promoter region. UCP3 was also found to be concomitantly expressed with IGF-1 during differentiation of C2C12 myoblasts. Our animal experiments showed that high fat diet induced IGF-1 levels which likely influenced UCP3 expression in the skeletal muscle. Conclusion Our findings demonstrate that that IGF-1 directly stimulates UCP3 expression via the IGF-1/IGF-1R/PI3-Akt/FOXO4 pathway.

Objective We evaluated the direct action of GH signaling in energy homeostasis in myocytes. Design We investigated the GH-induced expression of UCP3 in human embryonic kidney 293 cells, human H-EMC-SS chondrosarcoma cells, murine C2C12 skeletal muscle myoblasts, and rat L6 skeletal muscle cells, as well as its direct effect on the GHR/JAK/STAT5 pathway using a combination of a reporter assay, real-time quantitative polymerase chain reaction, and western blotting. Results We demonstrated that the regulation of energy metabolism by GH involves UCP3 via activated STAT5, a signal transducer downstream of GH. UCP3 expression increased with STAT5 in a dose-dependent manner and was higher than that of UCP2. We confirmed the functional STAT5 binding site consensus sequences at −861 and −507 bp in the UCP3 promoter region. Conclusion The results suggest that GH stimulates UCP3 directly and that UCP2 and that UCP3 participate in the signal transduction pathway that functions downstream of the GHR/JAK/STAT.

Cigarette smoke contains over 4800 compounds, including at least 200 toxicants or endocrine disruptors. Currently, effects of cigarette smoke on thyroid hormone (TH) levels remains to be clarified. Here, we demonstrate that cigarette smoke extract (CSE) possesses thyroid hormone properties and acts synergistically as a partial agonist for thyroid hormone receptors (TRs) in the presence of TH. In transient gene expression experiments, CSE stimulated transcriptional activity with TH in a dose-dependent manner. Stimulatory effects were observed with physiological TH concentrations, although CSE did not activate TRs without TH. CSE (5%) dissolved in phosphate-buffered saline (PBS) supplemented with 1 nM TH was approximately comparable to 3.2±0.1 and 2.3±0.2 nM of TRα1 and TRβ1, respectively. To illustrate probable mechanisms of the CSE agonistic activity, effects on TR mediated transcriptional functions with cofactors were investigated. With a mammalian two-hybrid assay, CSE recruited the nuclear coactivators glucocorticoid receptor interacting protein 1 (GRIP1) and steroid receptor coactivator 1 (SRC1) to the TR. Unsaturated carbonyl compounds, acrolein, crotonaldehyde, and methyl vinyl ketone, representative constituents of CSE, retained such agonistic properties and possibly contributed to stimulatory effects. The results suggest that CSE recruits a transcriptional activator and may reinforce TH binding to the TR additively, resulting in gene expression. CSE partially agonizes TH action and may disturb the function of various nuclear hormone receptor types and their cofactors to disrupt the physiological processes.

Objective The transition of white adipocytes to beige cells (a phenomenon referred to as browning or beigeing) during obesity has been previously reported. Our study aimed to examine the mechanisms through which obesity induced by a high fat diet (HFD) affects uncoupling protein 1 (UCP1) expression via signal transduction and activator of transcription 5 (STAT5s). Design Seven-week-old male C57BL/6J mice were fed a normal or HFD for 11 weeks. Body weight, white adipose tissue weight, and blood lipid and glucose levels were measured. To unveil the molecular mechanisms of UCP1 expression in adipose tissue, we performed further studying 3T3-L1 cells using qRT-PCR. We also measured UCP1 promoter activity in the TSA201 cell line using a dual luciferase assay. In addition, we analyzed the predicted consensus sequences for STAT5 binding in the UCP1 promoter region. Results Mice fed an HFD had higher body weight and intra-abdominal adipose tissues weight and a higher expression of UCP1, GH receptor (GHR), STATs, suppressors of cytokine signaling (SOCSs), and cytokine-inducible SH2-containing protein (CISH) compared to control mice. In 3T3-L1 cell studies, GH induced phosphorylation of the STAT5, SOCSs, CISH and UCP1 expressions. UCP1 promoter activity was associated with constitutively active STAT5 in a dose-dependent manner. We confirmed functional STAT5 binding sites at − 425, − 279, and − 178 bp of the UCP1 promoter. Conclusion We suggest that endogenous GH induces UCP1 expression in adipose tissue via STAT5.

Cigarette smoke extract (CSE) contains many toxicants and may derange the physiological processes, such as cholesterol metabolism. We examined the impact of CSE on transcriptional regulation mediated peroxisome proliferator-activated receptors (PPARs) and its interaction with cofactors to elucidate differences in the molecular mechanism between CSE and other agonists of PPARs. We constructed several mutant PPARs (mPPARs) with amino acid substitution in the ligand-binding domain, which according to the molecular modeling, may affect the binding of agonists. In transient expression assays, each wild-type peroxisome proliferator-activated receptor (PPAR) mediated transcription stimulated by CSE was faintly yet significantly elevated compared to the control. The CSE-induced transcriptional activation was abolished in the H323A, H323Y, S342A, and H449A mPPARγs, although the activation elevated by pioglitazone was reserved. In the mPPARγ with Y473A and mPPARβ/δs with H286Y and Y436A, the pioglitazone-induced or L165041-activated transcriptional elevations were decreased and were lower than that of CSE-induced stimulation. These results suggested that CSE activated both mutant PPARs to be selectively different from those ligands. Mammalian two-hybrid assay illustrated that CSE could mildly recruit SRC1 or GRIP1 to the wild-type PPARγ. Representative ingredients, such as acrolein and crotonaldehyde present in CSE, could stimulate PPAR isoforms even at the toxicological concentrations and might possibly contribute to stimulatory effects. CSE mildly regulates the cholesterol metabolism-related genes, such as low density lipoprotein (LDL) receptor and Liver X receptor (LXR)β. In conclusion, these CSE effects the nuclear hormone receptors and their cofactors thereby disturbing metabolic phenomena. Therefore, CSE might be involved in cholesterol metabolism.

Our earlier study indicated that [P4444]CF3COO salt in binary aqueous solution was found an extremely strong hydrophobe. Here, we examine its hydrophobicity by the 1-propanol probing methodology we have developed earlier. The results indicated contrary to our expectation the salt was in fact the most significant amphiphile with a strong hydrophobic and an equally strong hydrophilic contributions; indeed the strongest ones we have encountered. We discuss a possible interpretation why and how such surprising results came about.

O hidrogênio é um átomo de tamanho reduzido que consegue se difundir rapidamente pela malha cristalina de estruturas metálicas. Essa permeação pode prejudicar as propriedades mecânicas de componentes de diversos setores industriais, principalmente quando em contato com as fontes de hidrogênio como o H2S. O desgaste é designado fragilização por hidrogênio, e o material adquire susceptibilidade à formação de falhas e de fraturas frágeis. Esse trabalho foi desenvolvido com o objetivo de compreender os mecanismos para a permeação da espécie em aço ultrabaixo carbono Interstitial Free, cuja simplicidade microestrutural reduz as variáveis envolvidas no fenômeno e facilita uma compreensão sobre ligas mais complexas. O foco foi verificar a influência da fração recristalizada e do acabamento superficial no comportamento das curvas de permeação, pelo uso da polarização eletroquímica e da célula de Devanathan-Stachurski. Os coeficientes de difusão das quatro condições do aço (full hard, parcialmente recozido, IF, IF lixado) foram comparados entre si, considerando os valores teórico pela Lei de Fick e experimental. Dentre eles, o full hard mostrou maior dificuldade para permeação do hidrogênio devido às discordâncias, e o IF, grande facilidade após o alívio das tensões internas pelo tratamento térmico. Já a redução na rugosidade superficial prejudicou o mecanismo de entrada do hidrogênio, resultando numa permeação mais restrita. Os comportamentos das curvas foram relacionados às características de cada amostra e revelaram associação entre defeitos e dureza do metal com os aprisionamentos do hidrogênio e falhas, como trincas e blisters. Efeitos sobre o metal foram analisados por testes metalográficos dos corpos-de-prova, para identificação das alterações microestruturais. Hydrogen is a small size atom that can rapidly spread through the lattice of metal structures. This permeation may affect the mechanical properties of components from several industrial areas, especially when these parts are in contact with sources of hydrogen such as H2S. The wear effect is referred to as hydrogen embrittlement, which makes the material more susceptible to the formation of fragile fractures. This work was developed with the aim of understanding the mechanisms for the permeation of the specie in ultra-low carbon steel Interstitial Free, in which the microstructural simplicity reduces the parameters involved in the phenomenon and facilitates the comprehension about more complex alloys. The focus was to investigate the influences of recrystaliised fraction and surface roughness on the permeation curves behavior by using electrochemical polarization and Devanathan-Stachurski cell. Diffusion coefficients for the four determined steel conditions (full hard, partially annealed, IF, surface finished IF) were compared to each other, considering the theoretical values from Fick's Law and experimental values. Among those different conditions, it was slightly more difficult for full hard steel to demonstrate hydrogen permeation due to dislocations, on the other hand, IF steel presented an easy permeation after releasing internal stresses by means of heat treatment. The decrease in surface roughness impaired the specie input mechanism, resulting in a more restricted permeation. The behavior of the permeation curves were related to the characteristics of each sample and revealed an association between defects and metal hardness with the hydrogen traps and failures, as cracks and blisters. Effects on the steel were analyzed by metallographic tests for identification of microstructural modifications.