A compound directed against S6K1 hampers fat mass expansion and mitigates diet-induced hepatosteatosis.

The ribosomal protein S6 kinase 1 (S6K1) is a relevant effector downstream of the mammalian target of rapamycin complex 1 (mTORC1), best known for its role in the control of lipid homeostasis. Consistent with this, mice lacking the S6k1 gene have a defect in their ability to induce the commitment of fat precursor cells to the adipogenic lineage, which contributes to a significant reduction of fat mass. Here, we assess the therapeutic blockage of S6K1 in diet-induced obese mice challenged with LY2584702 tosylate, a specific oral S6K1 inhibitor initially developed for the treatment of solid tumors. We show that diminished S6K1 activity hampers fat mass expansion and ameliorates dyslipidemia and hepatic steatosis, while modifying transcriptome-wide gene expression programs relevant for adipose and liver function. Accordingly, decreased mTORC1 signaling in fat (but increased in the liver) segregated with defective epithelial-mesenchymal transition and the impaired expression of Cd36 (coding for a fatty acid translocase) and Lgals1 (Galectin 1) in both tissues. All these factors combined align with reduced adipocyte size and improved lipidomic signatures in the liver, while hepatic steatosis and hypertriglyceridemia were improved in treatments lasting either 3 months or 6 weeks.

Human VGF-Derived Antidepressant Neuropeptide TLQP62 Promotes SH-SY5Y Neurite Outgrowth.

TLQP62 is a neuropeptide derived from the neurotrophin-inducible VGF (non-acronymic) protein with antidepressant-like properties capable of inducing increased memory on the mouse hippocampus by promoting neurogenesis and synaptic plasticity through brain-derived neurotropic factor (BDNF) and its receptor tyrosine receptor kinase B (TrkB). Human SH-SY5Y neuroblastoma-derived cell line is widely used in neuroscience research and is known to undergo neurodifferentiation in the presence of all-trans retinoic acid by upregulating the expression of TrkB, making cells responsive to BDNF. As TLQP62 promotes BDNF expression, which in turn activates a BDNF/TrkB/CREB (cAMP response element-binding protein) pathway that upregulates VGF expression, there is a VGF-BDNF regulatory loop that seems to regulate neurogenesis. Therefore, here, we evaluate by morphological observation the ability of human TLQP62 to induce neuritogenesis of human SH-SY5Y neuroblastoma-derived cell line in a retinoic acid and BDFN-like way, making this cell line a suitable cell model for further studies concerning TLQP62 molecular mechanisms and signalling pathways. SIGNIFICANCE STATEMENT: VGF has been widely explored for its role in emotional behaviour and neuropsychiatric illness (Bartolomucci et al. 2011). Although VGF levels were found reduced in leukocytes of depressed patients, after antidepressant treatment or voluntary exercise, those levels were found to be restored in the hippocampus (Hunsberger et al. 2007; Thakker-Varia et al. 2007). Administration to hippocampal cells of TLQP62 produced an increase in synaptic charge that could explain this antidepressants effects (Alder et al. 2003). This interesting role of TLQP62 in the brain, especially in the hippocampus, makes this neuropeptide an attractive target for further investigation of its role in neurogenesis, learning, memory, and neurological disorders, and possible treatment development. Thus, the identification of a receptor(s) for this peptide and associated signalling pathway(s) is of high importance, as well as a proper cell model to perform those studies.

Deficient Endoplasmic Reticulum-Mitochondrial Phosphatidylserine Transfer Causes Liver Disease.

Non-alcoholic fatty liver is the most common liver disease worldwide. Here, we show that the mitochondrial protein mitofusin 2 (Mfn2) protects against liver disease. Reduced Mfn2 expression was detected in liver biopsies from patients with non-alcoholic steatohepatitis (NASH). Moreover, reduced Mfn2 levels were detected in mouse models of steatosis or NASH, and its re-expression in a NASH mouse model ameliorated the disease. Liver-specific ablation of Mfn2 in mice provoked inflammation, triglyceride accumulation, fibrosis, and liver cancer. We demonstrate that Mfn2 binds phosphatidylserine (PS) and can specifically extract PS into membrane domains, favoring PS transfer to mitochondria and mitochondrial phosphatidylethanolamine (PE) synthesis. Consequently, hepatic Mfn2 deficiency reduces PS transfer and phospholipid synthesis, leading to endoplasmic reticulum (ER) stress and the development of a NASH-like phenotype and liver cancer. Ablation of Mfn2 in liver reveals that disruption of ER-mitochondrial PS transfer is a new mechanism involved in the development of liver disease.

Mitochondrial Complex I Activity Is Required for Maximal Autophagy.

Cells adapt to nutrient and energy deprivation by inducing autophagy, which is regulated by the mammalian target of rapamycin (mTOR) and AMP-activated protein kinases (AMPKs). We found that cell metabolism significantly influences the ability to induce autophagy, with mitochondrial complex I function being an important factor in the initiation, amplitude, and duration of the response. We show that phenformin or genetic defects in complex I suppressed autophagy induced by mTOR inhibitors, whereas autophagy was enhanced by strategies that increased mitochondrial metabolism. We report that mTOR inhibitors significantly increased select phospholipids and mitochondrial-associated membranes (MAMs) in a complex I-dependent manner. We attribute the complex I autophagy defect to the inability to increase MAMs, limiting phosphatidylserine decarboxylase (PISD) activity and mitochondrial phosphatidylethanolamine (mtPE), which support autophagy. Our data reveal the dynamic and metabolic regulation of autophagy.

Phenformin-Induced Mitochondrial Dysfunction Sensitizes Hepatocellular Carcinoma for Dual Inhibition of mTOR.

Purpose: Hepatocellular carcinoma (HCC) ranks second in cancer mortality and has limited therapeutic options. We recently described the synergistic effect of allosteric and ATP-site competitive inhibitors against the mTOR for the treatment of HCC. However, such inhibitors induce hyperglycemia and increase mitochondrial efficiency. Here we determined whether the mitochondrial complex I inhibitor phenformin could reverse both side effects, impose an energetic stress on cancer cells, and suppress the growth of HCC.Experimental Design: Human HCC cell lines were used in vitro to access the signaling and energetic impact of mTOR inhibitors and phenformin, either alone or in combination. Next, the therapeutic utility of these drugs alone or in combination was investigated preclinically in human orthotopic tumors implanted in mice, by analyzing their impact on the tumor burden and overall survival.Results: We found phenformin caused mitochondrial dysfunction and fragmentation, inducing a compensatory shift to glycolysis. In contrast, dual inhibition of mTOR impaired cell growth and glycolysis, while increasing mitochondrial fusion and efficiency. In a mouse model of human HCC, dual inhibition of mTOR, together with phenformin, was highly efficacious in controlling tumor burden. However, more strikingly, pretreatment with phenformin sensitized tumors to dual inhibition of mTOR, leading to a dramatic improvement in survival.Conclusions: Treatment of HCC cells in vitro with the biguanide phenformin causes a metabolic shift to glycolysis, mitochondrial dysfunction and fragmentation, and dramatically sensitizes orthotopic liver tumors to dual inhibition of mTOR. We therefore propose this therapeutic approach should be tested clinically in HCC. Clin Cancer Res; 24(15); 3767-80. ©2018 AACR.

Recombinant PrPSc shares structural features with brain-derived PrPSc: Insights from limited proteolysis.

Very solid evidence suggests that the core of full length PrPSc is a 4-rung ß-solenoid, and that individual PrPSc subunits stack to form amyloid fibers. We recently used limited proteolysis to map the ß-strands and connecting loops that make up the PrPSc solenoid. Using high resolution SDS-PAGE followed by epitope analysis, and mass spectrometry, we identified positions ~116/118, 133-134, 141, 152-153, 162, 169 and 179 (murine numbering) as Proteinase K (PK) cleavage sites in PrPSc. Such sites likely define loops and/or borders of ß-strands, helping us to predict the threading of the ß-solenoid. We have now extended this approach to recombinant PrPSc (recPrPSc). The term recPrPSc refers to bona fide recombinant prions prepared by PMCA, exhibiting infectivity with attack rates of ~100%. Limited proteolysis of mouse and bank vole recPrPSc species yielded N-terminally truncated PK-resistant fragments similar to those seen in brain-derived PrPSc, albeit with varying relative yields. Along with these fragments, doubly N- and C-terminally truncated fragments, in particular ~89/97-152, were detected in some recPrPSc preparations; similar fragments are characteristic of atypical strains of brain-derived PrPSc. Our results suggest a shared architecture of recPrPSc and brain PrPSc prions. The observed differences, in particular the distinct yields of specific PK-resistant fragments, are likely due to differences in threading which result in the specific biochemical characteristics of recPrPSc. Furthermore, recombinant PrPSc offers exciting opportunities for structural studies unachievable with brain-derived PrPSc.

Proteomic Studies Reveal Disrupted in Schizophrenia 1 as a Player in Both Neurodevelopment and Synaptic Function.

A balanced chromosomal translocation disrupting DISC1 (Disrupted in Schizophrenia 1) gene has been linked to psychiatric diseases, such as major depression, bipolar disorder and schizophrenia. Since the discovery of this translocation, many studies have focused on understating the role of the truncated isoform of DISC1, hypothesizing that the gain of function of this protein could be behind the neurobiology of mental conditions, but not so many studies have focused in the mechanisms impaired due to its loss of function. For that reason, we performed an analysis on the cellular proteome of primary neurons in which DISC1 was knocked down with the goal of identifying relevant pathways directly affected by DISC1 loss of function. Using an unbiased proteomic approach, we found that the expression of 31 proteins related to neurodevelopment (e.g., CRMP-2, stathmin) and synaptic function (e.g., MUNC-18, NCS-1) is altered by DISC1 in primary mouse neurons. Hence, this study reinforces the idea that DISC1 is a unifying regulator of both neurodevelopment and synaptic function, thereby providing a link between these two key anatomical and cellular circuitries.

Role of Mitochondrial Complex IV in Age-Dependent Obesity.

Aging is associated with progressive white adipose tissue (WAT) enlargement initiated early in life, but the molecular mechanisms involved remain unknown. Here we show that mitochondrial complex IV (CIV) activity and assembly are already repressed in white adipocytes of middle-aged mice and involve a HIF1A-dependent decline of essential CIV components such as COX5B. At the molecular level, HIF1A binds to the Cox5b proximal promoter and represses its expression. Silencing of Cox5b decreased fatty acid oxidation and promoted intracellular lipid accumulation. Moreover, local in vivo Cox5b silencing in WAT of young mice increased the size of adipocytes, whereas restoration of COX5B expression in aging mice counteracted adipocyte enlargement. An age-dependent reduction in COX5B gene expression was also found in human visceral adipose tissue. Collectively, our findings establish a pivotal role for CIV dysfunction in progressive white adipocyte enlargement during aging, which can be restored to alleviate age-dependent WAT expansion.

Effect of low doses of actinomycin D on neuroblastoma cell lines.

BACKGROUND: Neuroblastoma is a malignant embryonal tumor occurring in young children, consisting of undifferentiated neuroectodermal cells derived from the neural crest. Current therapies for high-risk neuroblastoma are insufficient, resulting in high mortality rates and high incidence of relapse. With the intent to find new therapies for neuroblastomas, we investigated the efficacy of low-doses of actinomycin D, which at low concentrations preferentially inhibit RNA polymerase I-dependent rRNA trasncription and therefore, ribosome biogenesis. METHODS: Neuroblastoma cell lines with different p53 genetic background were employed to determine the response on cell viability and apoptosis of low-dose of actinomycin D. Subcutaneously-implanted SK-N-JD derived neuroblastoma tumors were used to assess the effect of low-doses of actinomycin D on tumor formation. RESULTS: Low-dose actinomycin D treatment causes a reduction of cell viability in neuroblastoma cell lines and that this effect is stronger in cells that are wild-type for p53. MYCN overexpression contributes to enhance this effect, confirming the importance of this oncogene in ribosome biogenesis. In the wild-type SK-N-JD cell line, apoptosis was the major mechanism responsible for the reduction in viability and we demonstrate that treatment with the MDM2 inhibitor Nutlin-3, had a similar effect to that of actinomycin D. Apoptosis was also detected in p53(-/-)deficient LA1-55n cells treated with actinomycin D, however, only a small recovery of cell viability was found when apoptosis was inhibited by a pan-caspase inhibitor, suggesting that the treatment could activate an apoptosis-independent cell death pathway in these cells. We also determined whether actinomycin D could increase the efficacy of the histone deacetylase inhibitor, SAHA, which is in being used in neuroblastoma clinical trials. We show that actinomycin D synergizes with SAHA in neuroblastoma cell lines. Moreover, on subcutaneously-implanted neuroblastoma tumors derived from SK-N-JD cells, actinomycin D led to tumor regression, an effect enhanced in combination with SAHA. CONCLUSIONS: The results presented in this work demonstrate that actinomycin D, at low concentrations, inhibits proliferation and induces cell death in vitro, as well as tumor regression in vivo. From this study, we propose that use of ribosome biogenesis inhibitors should be clinically considered as a potential therapy to treat neuroblastomas.

Neuroprotective effects of dexmedetomidine conditioning strategies: Evidences from an in vitro model of cerebral ischemia.

AIMS: Dexmedetomidine is a selective agonist of α2-adrenergic receptors with clinical anesthetic and analgesic properties that has also shown neuroprotective effects on several models of brain injury. Because perioperative stroke and brain damage are frequent causes of death in critical care units, we aimed to investigate neuroprotective properties of dexmedetomidine using an in vitro model of cerebral ischemia. MAIN METHODS: Primary mixed rat brain cortical cultures were subjected to oxygen and glucose deprivation and treated with different doses of dexmedetomidine in order to analyze three conditioning strategies: preconditioning, intraconditioning and postconditioning. KEY FINDINGS: All dexmedetomidine pre-, intra- and postconditioning treatments showed neuroprotective effects reducing brain cell necrosis, although only preconditioning showed antiapoptotic effects. Dexmedetomidine treatments also reduced IL-6 and TNF-α levels, especially in the preconditioning groups. Oxidative stress was attenuated with all dexmedetomidine preconditioning treatments, but only with the higher dose in the intraconditioning group, and no effects were observed in the postconditioning. All conditioning strategies increased BDNF levels. SIGNIFICANCE: Dexmedetomidine-mediated neuroprotective effects in an in vitro model of cerebral ischemia involve the attenuation of inflammation and oxidative stress and the increment of BDNF expression.

Neuropeptide precursor VGF is genetically associated with social anhedonia and underrepresented in the brain of major mental illness: its downregulation by DISC1.

In a large Scottish pedigree, disruption of the gene coding for DISC1 clearly segregates with major depression, schizophrenia and related mental conditions. Thus, study of DISC1 may provide a clue to understand the biology of major mental illness. A neuropeptide precursor VGF has potent antidepressant effects and has been reportedly associated with bipolar disorder. Here we show that DISC1 knockdown leads to a reduction of VGF, in neurons. VGF is also downregulated in the cortices from sporadic cases with major mental disease. A positive correlation of VGF single-nucleotide polymorphisms (SNPs) with social anhedonia was also observed. We now propose that VGF participates in a common pathophysiology of major mental disease.

Inter-relações entre forças influenciadoras e cultura organizacional / Interrelations between influencing forces and organizational culture / Interrelaciones entre las fuerzas influyentes e la cultura organizacional

Foi testada a afirmação da teoria da adequação cultural de Handy segundo a qual forças influenciadoras (tamanho da empresa, ciclos de vida, padrões de trabalho e pessoas) relacionam-se a diferentes combinações culturais. Foram pesquisadas e comparadas duas empresas bem-sucedidas. Dados relativos às forças influenciadoras foram obtidos por meio de entrevistas estruturadas com gestores. Junto aos empregados, por meio de questionário, foram levantados dados pessoais e aplicadas escalas validadas por Gomide e Martins que medem, com base na teoria de Handy, culturas de clube, de função, de tarefa e existencial. Os resultados evidenciaram diferenças significativas entre as empresas nas culturas de função, tarefa e existencial. As forças influenciadoras sugerem explicações para essas diferenças. Foi possível diagnosticar as organizações e recomendar ajustes às empresas.

It was tested the assertion, encountered in Handy's cultural adequacy theory, that influencing forces over the enterprises (size, life cycles, work patterns and persons) are related to different cultural mixtures. Two successful enterprises were investigated and compared. Data concerning the influencing forces were obtained by means of structured interviews with managers. With the employees, a questionnaire was applied to obtain personal data and the Gomide and Martins' validated scales that measure, according to Handy's theory, club, function, task and existential cultures. The results showed that there are significant differences between the two enterprises involving task, function and existential cultures. The influencing forces suggest explanations for these differences. It was possible to arrive at organizational diagnostics and suggest adjustments to the enterprises.

Hemos probado la afirmación de la teoría de la adecuación cultural de Handy por la cual las fuerzas influyentes (tamaño de la empresa, los ciclos de vida, patrones de trabajo y las personas) están relacionadas con diferentes combinaciones culturales. Se investigó y comparó dos empresas de éxito. Los datos sobre las fuerzas influyentes fueron obtenidos a través de entrevistas estructuradas con los directores. Con los empleados, a través de un cuestionario, fueron recogidos los datos personales yfueron aplicadas escalas validadas por Gomide y Martins que meden, de acuerdo a la teoría de Handy, las culturas de club, función, tarea y existencial. Los resultados mostraron diferencias significativas entre las empresas en las culturas de función, tarea, y existencial. Fuerzas influyentes sugieren explicaciones para estas diferencias. Se pudo diagnosticar las organizaciones y recomendar ajustes a las empresas.