Genomic actions of 1,25-dihydroxyvitamin D3 on insulin receptor gene expression, insulin receptor number and insulin activity in the kidney, liver and adipose tissue of streptozotocin-induced diabetic rats

<p>Abstract</p> <p>Background</p> <p>this study set out to examine the effects of the treatment with 1,25-dihydroxyvitamin D₃(<it>1,25D</it>₃) [150 IU/Kg (3.75 μg/Kg) one a day, for 15 days] to non-diabetic rats and in rats rendered diabetic by a single injection of streptozotocin [65 mg/kg].</p> <p>Results</p> <p>treatment with <it>1,25D</it>₃to non-diabetic rats did not affect the biochemical parameters measured in the plasma and urine of these animals. Likewise, insulin receptor expression in the kidney, liver, or adipose tissue and insulin-stimulated glucose transport in adipocytes from these animals were not affected either. Treatment with <it>1,25D</it>₃to streptozotocin-induced diabetic rats did not correct the hyperglycemia, hypoinsulinemia, glycosuria or ketonemia induced by the diabetes, although it partially reversed the over-expression of the insulin receptor gene in the liver and adipose tissue, without altering the normal expression of this gene in the kidney. These effects were accompanied by a normalization of the number of insulin receptors without altering receptor affinity but improving the insulin response to glucose transport in adipocytes from these diabetic animals. Moreover, a computer search in the rat insulin receptor promoter revealed the existence of two candidate vitamin D response element (VDRE) sequences located at -256/-219 bp and -653/-620 bp, the first overlapped by three and the second by four AP-2-like sites.</p> <p>Conclusion</p> <p>these genomic actions of <it>1,25D</it>₃could represent beneficial effects associated with the amelioration of diabetes via mechanisms that possibly involve direct transcriptional activation of the rat insulin receptor gene. The candidate VDREs identified may respond to <it>1,25D</it>₃via activation of the vitamin D receptor, although this remains to be investigated.</p

A53T-alpha-synuclein overexpression impairs dopamine signaling and striatal synaptic plasticity in old mice

BACKGROUND: Parkinson's disease (PD), the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression or the A53T missense mutation of the presynaptic protein alpha-synuclein (SNCA). PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons. METHODOLOGY/PRINCIPAL FINDINGS: Here, we used two mouse lines overexpressing human A53T-SNCA and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. To characterize the progression, we employed young adult as well as old mice. Analysis of striatal neurotransmitter content demonstrated that dopamine (DA) levels correlated directly with the level of expression of SNCA, an observation also made in SNCA-deficient (knockout, KO) mice. However, the elevated DA levels in the striatum of old A53T-SNCA overexpressing mice may not be transmitted appropriately, in view of three observations. First, a transcriptional downregulation of the extraneural DA degradation enzyme catechol-ortho-methytransferase (COMT) was found. Second, an upregulation of DA receptors was detected by immunoblots and autoradiography. Third, extensive transcriptome studies via microarrays and quantitative real-time RT-PCR (qPCR) of altered transcript levels of the DA-inducible genes Atf2, Cb1, Freq, Homer1 and Pde7b indicated a progressive and genotype-dependent reduction in the postsynaptic DA response. As a functional consequence, long term depression (LTD) was absent in corticostriatal slices from old transgenic mice. CONCLUSIONS/SIGNIFICANCE: Taken together, the dysfunctional neurotransmission and impaired synaptic plasticity seen in the A53T-SNCA overexpressing mice reflect early changes within the basal ganglia prior to frank neurodegeneration. As a model of preclinical stages of PD, such insights may help to develop neuroprotective therapeutic approaches

Antioxidants can inhibit basal autophagy and enhance neurodegeneration in models of polyglutamine disease.

Many neurodegenerative diseases exhibit protein accumulation and increased oxidative stress. Therapeutic strategies include clearing aggregate-prone proteins by enhancing autophagy or decreasing oxidative stress with antioxidants. Many autophagy-inducing stimuli increase reactive oxygen species (ROS), raising concerns that the benefits of autophagy up-regulation may be counterbalanced by ROS toxicity. Here we show that not all autophagy inducers significantly increase ROS. However, many antioxidants inhibit both basal and induced autophagy. By blocking autophagy, antioxidant drugs can increase the levels of aggregate-prone proteins associated with neurodegenerative disease. In fly and zebrafish models of Huntington's disease, antioxidants exacerbate the disease phenotype and abrogate the rescue seen with autophagy-inducing agents. Thus, the potential benefits in neurodegenerative diseases of some classes of antioxidants may be compromised by their autophagy-blocking properties

A53T-Alpha-Synuclein Overexpression Impairs Dopamine Signaling and Striatal Synaptic Plasticity in Old Mice

Parkinson's disease (PD), the second most frequent neurodegenerative disorder at old age, can be caused by elevated expression or the A53T missense mutation of the presynaptic protein alpha-synuclein (SNCA). PD is characterized pathologically by the preferential vulnerability of the dopaminergic nigrostriatal projection neurons.Here, we used two mouse lines overexpressing human A53T-SNCA and studied striatal dysfunction in the absence of neurodegeneration to understand early disease mechanisms. To characterize the progression, we employed young adult as well as old mice. Analysis of striatal neurotransmitter content demonstrated that dopamine (DA) levels correlated directly with the level of expression of SNCA, an observation also made in SNCA-deficient (knockout, KO) mice. However, the elevated DA levels in the striatum of old A53T-SNCA overexpressing mice may not be transmitted appropriately, in view of three observations. First, a transcriptional downregulation of the extraneural DA degradation enzyme catechol-ortho-methytransferase (COMT) was found. Second, an upregulation of DA receptors was detected by immunoblots and autoradiography. Third, extensive transcriptome studies via microarrays and quantitative real-time RT-PCR (qPCR) of altered transcript levels of the DA-inducible genes Atf2, Cb1, Freq, Homer1 and Pde7b indicated a progressive and genotype-dependent reduction in the postsynaptic DA response. As a functional consequence, long term depression (LTD) was absent in corticostriatal slices from old transgenic mice.Taken together, the dysfunctional neurotransmission and impaired synaptic plasticity seen in the A53T-SNCA overexpressing mice reflect early changes within the basal ganglia prior to frank neurodegeneration. As a model of preclinical stages of PD, such insights may help to develop neuroprotective therapeutic approaches

Cannabinoid agonists showing BuChE inhibition as potential therapeutic agents for Alzheimer's disease

Designing drugs with a specific multi-target profile is a promising approach against multifactorial illnesses as Alzheimer's disease. In this work, new indazole ethers that possess dual activity as both cannabinoid agonists CB2 and inhibitors of BuChE have been designed by computational methods. On the basis of this knowledge, the synthesis, pharmacological evaluation and docking studies of a new class of indazoles has been performed. Pharmacological evaluation includes radioligand binding assays with [3H]-CP55940 for CB1R and CB2R and functional activity for cannabinoid receptors on isolated tissue. Additionally, in vitro inhibitory assays of AChE/BuChE and the corresponding competition studies have been carried out. The results of pharmacological tests have revealed that three of these derivatives behave as CB2 cannabinoid agonists and simultaneously show BuChE inhibition. In particular, compounds 3 and 24 have emerged as promising candidates as novel cannabinoids that inhibit BuChE by a non-competitive or mixed mechanism, respectively. On the other hand, both molecules show antioxidant properties. © 2013 Elsevier Masson SAS. All rights reserved.Peer Reviewe

High efficacy of Sofosbuvir plus Simeprevir in a large cohort of Spanish cirrhotic patients infected with genotypes 1 and 4

[Abstract] Background and Aims. Hepatitis C (HCV) therapy with Sofosbuvir (SOF)/Simeprevir (SMV) in clinical trials and real‐world clinical practice, showed high rates of sustained virological response (SVR) in non‐cirrhotic genotype (GT)‐1 and GT‐4 patients. These results were slightly lower in cirrhotic patients. We investigated real‐life effectiveness and safety of SOF/SMV with or without ribavirin (RBV) in a large cohort of cirrhotic patients. Methods. This collaborative multicentre study included data from 968 patients with cirrhosis infected with HCV‐GT1 or 4, treated with SOF/SMV±RBV in 30 centres across Spain between January‐2014 and December‐2015. Demographic, clinical, virological and safety data were analysed. Results. Overall SVR was 92.3%; the majority of patients were treated with RBV (62%) for 12 weeks (92.4%). No significant differences in SVR were observed between genotypes (GT1a:94.3%; GT1b:91.7%; GT4:91.1%). Those patients with more advanced liver disease (Child B/C, MELD≥10) or portal hypertension (platelet count≤100×109/L, transient elastography≥21 Kpa) showed significantly lower SVR rates (84.4%‐91.9%) than patients with less advanced liver disease (93.8%‐95.9%, P<.01 in all cases). In the multivariate analysis, the use of RBV, female gender, baseline albumin≥35 g/L, MELD<10 and lack of exposure to a triple therapy regimen were independent predictors of SVR (P<.05). Serious adverse events (SAEs) and SAE‐associated discontinuation events occurred in 5.9% and 2.6%. Conclusions. In this large cohort of cirrhotic patients managed in the real‐world setting in Spain, SOF/SMV±RBV yielded to excellent SVR rates, especially in patients with compensated liver cirrhosis. In addition, this combination showed to be safe, with low rates of SAEs and early discontinuations.Instituto de Salud Carlos III; PI15/0015

Autophagy and misfolded proteins in neurodegeneration

AbstractThe accumulation of misfolded proteins in insoluble aggregates within the neuronal cytoplasm is one of the common pathological hallmarks of most adult-onset human neurodegenerative diseases. The clearance of these misfolded proteins may represent a promising therapeutic strategy in these diseases. The two main routes for intracellular protein degradation are the ubiquitin–proteasome and the autophagy–lysosome pathways. In this review, we will focus on the autophagic pathway, by providing some examples of how impairment at different steps in this degradation pathway is related to different neurodegenerative diseases. We will also consider that upregulating autophagy may be useful in the treatment of some of these diseases. Finally, we discuss how antioxidants, which have been considered to be beneficial in neurodegenerative diseases, can block autophagy, thus potentially compromising their therapeutic potential