Dietary Methionine Restriction Regulates Liver Protein Synthesis and Gene Expression Independently of Eukaryotic Initiation Factor 2 Phosphorylation in Mice

Background: The phosphorylation of eukaryotic initiation factor 2 (p-eIF2) during dietary amino acid insufficiency reduces protein synthesis and alters gene expression via the integrated stress response (ISR).Objective: We explored whether a Met-restricted (MR) diet activates the ISR to reduce body fat and regulate protein balance.Methods: Male and female mice aged 3-6 mo with either whole-body deletion of general control nonderepressible 2 (Gcn2) or liver-specific deletion of protein kinase R-like endoplasmic reticulum kinase (Perk) alongside wild-type or floxed control mice were fed an obesogenic diet sufficient in Met (0.86%) or an MR (0.12% Met) diet for ≤5 wk. Ala enrichment with deuterium was measured to calculate protein synthesis rates. The guanine nucleotide exchange factor activity of eIF2B was measured alongside p-eIF2 and hepatic mRNA expression levels at 2 d and 5 wk. Metabolic phenotyping was conducted at 4 wk, and body composition was measured throughout. Results were evaluated with the use of ANOVA (P < 0.05).Results: Feeding an MR diet for 2 d did not increase hepatic p-eIF2 or reduce eIF2B activity in wild-type or Gcn2-/- mice, yet many genes transcriptionally regulated by the ISR were altered in both strains in the same direction and amplitude. Feeding an MR diet for 5 wk increased p-eIF2 and reduced eIF2B activity in wild-type but not Gcn2-/- mice, yet ISR-regulated genes altered in both strains similarly. Furthermore, the MR diet reduced mixed and cytosolic but not mitochondrial protein synthesis in both the liver and skeletal muscle regardless of Gcn2 status. Despite the similarities between strains, the MR diet did not increase energy expenditure or reduce body fat in Gcn2-/- mice. Finally, feeding the MR diet to mice with Perk deleted in the liver increased hepatic p-eIF2 and altered body composition similar to floxed controls.Conclusions: Hepatic activation of the ISR resulting from an MR diet does not require p-eIF2. Gcn2 status influences body fat loss but not protein balance when Met is restricted

UCP1 is an essential mediator of the effects of methionine restriction on energy balance but not insulin sensitivity

© FASEB. Dietary methionine restriction (MR) by 80%increases energy expenditure (EE), reduces adiposity, and improves insulin sensitivity. We propose that the MRinduced increase in EE limits fat deposition by increasing sympathetic nervous system-dependent remodeling of white adipose tissue and increasing uncoupling protein 1 (UCP1) expression in both white and brown adipose tissue. In independent assessments of the role of UCP1 as a mediator of MR\u27s effects on EE and insulin sensitivity, EE did not differ between wild-type (WT) and Ucp1-/- mice on the control diet, butMR increased EE by 31%and reduced adiposity by 25% in WT mice. In contrast, MR failed to increase EE or reduce adiposity in Ucp1-/- mice. However, MR was able to increase overall insulin sensitivity by 2.2-fold in both genotypes. Housing temperatures used to minimize (28°C) or increase (23°C) sympathetic nervous system activity revealed temperature-independent effects of the diet on EE. Metabolomics analysis showed that genotypic and dietary effects on white adipose tissue remodeling resulted in profound increases in fatty acid metabolism within this tissue. These findings establish that UCP1 is required for the MR-induced increase in EE but not insulin sensitivity and suggest that diet-induced improvements in insulin sensitivity are not strictly derived from dietary effects on energy balance

Leptin-induced lipolysis opposes the tonic inhibition of endogenous adenosine in white adipocytes

The aim of the present study was to gain insight into the signaling pathway used by leptin to stimulate lipolysis. The lipolytic rate of white adipocytes from sex- and age-matched lean (+/+) and fa/fa rats was determined in the absence or presence of leptin together with a number of agents acting at different levels of the signaling cascade. Leptin did not modify FSK-, dbcAMP-, and IBMX-stimulated lipolysis. Lipolysis can also be maximally stimulated by lowering media adenosine levels with adenosine deaminase (ADA), i.e., in the ligand-free state. Although ADA produced near maximal lipolysis in adipocytes of lean animals, only half of the maximal lipolytic rate (50.9+/-3.2%) was achieved in fat cells from fa/fa rats (P=0.0034). In adipocytes from lean animals preincubated with ADA, leptin caused a concentration-related stimulation of lipolysis (P=0.0001). However, leptin had no effect on the lipolytic activity of adipocytes in the ligand-free state from fa/fa rats. The adenosine A1 receptor agonist CPA effectively inhibited basal lipolysis in both lean and obese adipocytes (P=0.0001 and P=0.0090, respectively). Leptin had no effect on the lipolytic rate of adipocytes isolated from fa/fa rats and preincubated with CPA. When adipocytes were incubated with the A1 receptor antagonist DPCPX, a significant increase in glycerol release was observed in fa/fa fat cells (P=0.009), whereas cells isolated from lean rats showed no differences to ADA-stimulated lipolysis. After pretreatment with PTX, which inactivates receptor-mediated Gi function, adipocytes of obese rats became as responsive to the stimulatory actions of ISO as cells from lean rats (P=0.0090 vs. ISO in fa/fa rats; P=0.2416 vs. lean rats, respectively). PTX treatment of lean cells, however, did not alter their response to this lipolytic agent. It can be concluded that the lipolytic effect of leptin is located at the adenylate cyclase/Gi proteins level and that leptin-induced lipolysis opposes the tonic inhibition of endogenous adenosine in white adipocytes

Physiologic Responses to Dietary Sulfur Amino Acid Restriction in Mice Are Influenced by Atf4 Status and Biological Sex

Background: Dietary sulfur amino acid restriction (SAAR) improves body composition and metabolic health across several model organisms in part through induction of the integrated stress response (ISR). Objective: We investigate the hypothesis that activating transcription factor 4 (ATF4) acts as a converging point in the ISR during SAAR. Methods: Using liver-specific or global gene ablation strategies, in both female and male mice, we address the role of ATF4 during dietary SAAR. Results: We show that ATF4 is dispensable in the chronic induction of the hepatokine fibroblast growth factor 21 while being essential for the sustained production of endogenous hydrogen sulfide. We also affirm that biological sex, independent of ATF4 status, is a determinant of the response to dietary SAAR. Conclusions: Our results suggest that auxiliary components of the ISR, which are independent of ATF4, are critical for SAAR-mediated improvements in metabolic health in mice

The quality of options in strategic decision making: a study about creativity and completeness in business decision making

A qualidade das decisões estratégicas dos empresários está diretamente relacionada à capacidade que eles demonstram para encontrar alternativas criativas quando enfrentam os problemas de suas empresas. Essas alternativas podem ser geradas intuitivamente, utilizando heurísticas. As pesquisas sobre geração de alternativas têm indicado consistentemente que as pessoas não são eficientes nessa atividade. As explicações para esse fato, contidas na literatura sobre decisão, não são conclusivas e permitem especulações a respeito. Para explorar essa questão e relacioná-la ao administrador brasileiro, foi idealizado um experimento com 174 alunos de quatro cursos de MBA para avaliar a originalidade e a completude das alternativas. O experimento e a respectiva análise basearam-se na confluência da pesquisa experimental, oriunda da psicologia cognitiva da decisão, com as visões da ciência da decisão organizacional tradicional e o novo campo de estudo das decisões intuitivas ou naturalísticas. Para mensurar a criatividade das alternativas apresentadas durante o experimento, empregou-se o conceito de árvore hierárquica, que demonstrou ser uma poderosa ferramenta para a tipologia de alternativas. O resultado desse experimento confirmou o baixo desempenho em geração de alternativas dos gerentes e, ao mesmo tempo, indicou que, provavelmente, a etapa de geração de alternativas isolada da etapa de escolha pode melhorar a qualidade das alternativas. A heurística, por sua vez, não demonstrou influenciar o conjunto de alternativas geradas. _________________________________________________________________________________________ ABSTRACT: The quality of strategic decisions of executives is directly related to the ability they have to find creative alternatives when facing business problems. These alternatives could be generated intuitively, using heuristics. On the other hand, the researches on alternatives generation have consistently indicated that people are not efficient on this duty. The argument for that, contained in the decision’s literature, is not conclusive and it allows speculation about it. To explore this issue and relate it to the Brazilian Administration, an experiment was designed for 174 students of four courses of MBA. The experiment and the analysis were resulted from the confluence between the experimental research from decision cognitive psychology with science’s vision of the traditional organizational decision and the new field of study on naturalistic or intuitive decisions. To measure the creativity of the alternatives presented during the experiment, the concept of hierarchical tree was utilized and it has proved a powerful tool to the typology of alternatives. The result of this experiment confirmed the poor performance in alternatives generation by managers and at the same time, indicated that probably, the generation of options isolated of analysis can produce better quality of alternatives. The heuristic, do not demonstrated any influence on options generated

PULSATILE LUTEINIZING HORMONE SECRETION IN THE CASTRATE MALE BOVINE: EFFECTS OF TESTOSTERONE OR ESTRADIOL REPLACEMENT THERAPY

Luteinizing hormone (LH) secretory profiles have been determined for the male bovine following castration and steroid replacement therapy. Serum LH concentrations increased approximately threefold during the first week following castration and thereafter remained elevated (6.6 ± .7 ng/ml). Castrates not receiving steroid replacement showed a rhythmic pattern of LH release that was of high frequency (mean pulse interval; 85 ± 5 min) and high amplitude (mean peak concentration, 11.2 ± 1.4 ng/ml). Chronic administration of estradiol-17β via subdermal Silastic implants reduced mean serum LH concentrations (2.1 ± .3 ng/ml) and blocked the pulsatile pattern of LH release in all steers. Similar administration of testosterone suppressed mean serum LH and blocked pulsatile LH release in two of four animals. The number of implants used in this study provided physiological concentrations of estradiol (9.8 ± 1.5 pg/ml) and testosterone (4.1 + .2 ng/ml) in systemic blood for the two respective treatment groups. Differences in the LH secretory profiles among testosterone;implanted steers may have been related, in part, to differences in the amounts of steroid not bound to serum proteins. These findings demonstrate that estradiol is a particularly potent inhibitor of pulsatile LH secretion in the male bovine and suggest that gonadal steroid feedback on LH secretion may, in part, be imposed at the level of the hypothalamus. The mechanism for pulsatile LH release is discussed relative to a centrally-located luteinizing hormone releasing hormone pulse generator