Short-term type-1 diabetes differentially modulates 14-3-3 proteins in rat brain and liver

Insight into the hepatoprotective, hypolipidemic, and antidiabetic impacts of aliskiren in streptozotocin-induced diabetic liver disease in mice

BACKGROUND

Diabetic hepatopathy is a serious complication of poorly controlled diabetes mellitus. An efficient antidiabetic drug which keeps normal liver tissues is not available. The renin-angiotensin system has been reported to be involved in both diabetic state and liver function. Aliskiren is a direct renin inhibitor and a recently antihypertensive drug with poly-pharmacological properties. The aim of the current study is to explore the possible hepatoprotective effects and mechanisms of action of aliskiren against streptozotocin (STZ) induced liver toxicity.

METHODS

Mice were distributed to 3 groups; first: the normal control group, second: the diabetic control group, third: the diabetic group which received aliskiren (25 mg/kg; oral) for 4 weeks. At the end of the treatment period, plasma glucose, insulin, lipid profile, oxidative stress, and liver function tests were evaluated spectrophotometrically. ELISA technique was used to measure the expression levels of TNF-α and adiponectin. Furthermore, a Histopathological examination of liver samples was done.

RESULTS

It was shown that aliskiren treatment ameliorated the STZ-induced oxidative stress and elevated inflammatory biomarkers, hypercholesterolemia, serum aminotransferases and alkaline phosphatase levels in diabetic mice. In addition, hepatocellular necrosis, and fibrosis were improved by aliskiren treatment.

CONCLUSION

aliskiren protects against the liver damage caused by STZ-induced diabetes. This can be explained by its ability to block angiotensin-II, and its anti-diabetic, hypocholesterolemic, antioxidant and anti-inflammatory effects. Aliskiren could be a novel therapeutic strategy to prevent liver diseases associated with hypertension and diabetes mellitus.

Exploring Computational Data Amplification and Imputation for the Discovery of Type 1 Diabetes (T1D) Biomarkers from Limited Human Datasets

Background: Type 1 diabetes (T1D) is a devastating disease with serious health complications. Early T1D biomarkers that could enable timely detection and prevention before the onset of clinical symptoms are paramount but currently unavailable. Despite their promise, omics approaches have so far failed to deliver such biomarkers, likely due to the fragmented nature of information obtained through the single omics approach. We recently demonstrated the utility of parallel multi-omics for the identification of T1D biomarker signatures. Our studies also identified challenges. Methods: Here, we evaluated a novel computational approach of data imputation and amplification as one way to overcome challenges associated with the relatively small number of subjects in these studies. Results: Using proprietary algorithms, we amplified our quadra-omics (proteomics, metabolomics, lipidomics, and transcriptomics) dataset from nine subjects a thousand-fold and analyzed the data using Ingenuity Pathway Analysis (IPA) software to assess the change in its analytical capabilities and biomarker prediction power in the amplified datasets compared to the original. These studies showed the ability to identify an increased number of T1D-relevant pathways and biomarkers in such computationally amplified datasets, especially, at imputation ratios close to the “golden ratio” of 38.2%:61.8%. Specifically, the Canonical Pathway and Diseases and Functions modules identified higher numbers of inflammatory pathways and functions relevant to autoimmune T1D, including novel ones not identified in the original data. The Biomarker Prediction module also predicted in the amplified data several unique biomarker candidates with direct links to T1D pathogenesis. Conclusions: These preliminary findings indicate that such large-scale data imputation and amplification approaches are useful in facilitating the discovery of candidate integrated biomarker signatures of T1D or other diseases by increasing the predictive range of existing data mining tools, especially when the size of the input data is inherently limited.

Does Diabetes Induce the Vascular Endothelial Growth Factor (VEGF) Expression in Periodontal Tissues? A Systematic Review

Aim: Diabetes and periodontal disease are both chronic pathological conditions linked by several underlying biological mechanisms, in which the inflammatory response plays a critical role, and their association has been largely recognized. Recently, attention has been given to diabetes as an important mediator of vascular endothelial growth factor (VEGF) overexpression in periodontal tissues, by virtue of its ability to affect microvasculature. This review aims to summarize the findings from studies that explored VEGF expression in diabetic patients with periodontitis, compared to periodontally healthy subjects. Materials and Methods: A systematic literature review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A PubMed search of select medical subject heading (MeSH) terms was carried out to identify all studies reporting findings about VEGF expression in periodontal tissues of diabetic patients up to May 2018. The inclusion criteria were studies on VEGF expression in periodontally diseased tissues of diabetic patients compared with nondiabetic subjects, with any method of analysis, and published in the English language. Results: Eight articles met the inclusion criteria. Immunohistochemistry was used in six of the studies, reverse transcriptase polymerase chain reaction (real-time RT-PCR) aiming to quantify mRNA VEGF expression was used in one study, and ELISA analysis was used for one study. Compared with nondiabetic patients, a higher VEGF expression in gingival tissue and gingival crevicular fluid (GCF) samples in diabetic patients with periodontitis was reported. Conclusions: Overall, novel evidence for the VEGF expression within the periodontal tissue of diabetic patients paves the way for further studies on the role of this protein in neovascularization physiology and pathophysiology in microvasculature of the periodontium.

14-3-3 Proteins Are on the Crossroads of Cancer, Aging, and Age-Related Neurodegenerative Disease

14-3-3 proteins are a family of conserved regulatory adaptor molecules which are expressed in all eukaryotic cells. These proteins participate in a variety of intracellular processes by recognizing specific phosphorylation motifs and interacting with hundreds of target proteins. Also, 14-3-3 proteins act as molecular chaperones, preventing the aggregation of unfolded proteins under conditions of cellular stress. Furthermore, 14-3-3 proteins have been shown to have similar expression patterns in tumors, aging, and neurodegenerative diseases. Therefore, we put forward the idea that the adaptor activity and chaperone-like activity of 14-3-3 proteins might play a substantial role in the above-mentioned conditions. Interestingly, 14-3-3 proteins are considered to be standing at the crossroads of cancer, aging, and age-related neurodegenerative diseases. There are great possibilities to improve the above-mentioned diseases and conditions through intervention in the activity of the 14-3-3 protein family.

An account of fungal 14-3-3 proteins

14-3-3s are a group of relatively low molecular weight, acidic, dimeric, protein(s) conserved from single-celled yeast to multicellular vertebrates including humans. Despite lacking catalytic activity, these proteins have been shown to be involved in multiple cellular processes. Apart from their role in normal cellular physiology, recently these proteins have been implicated in various medical consequences. In this present review, fungal 14-3-3 protein localization, interactions, transcription, regulation, their role in the diverse cellular process including DNA duplication, cell cycle, protein trafficking or secretion, apoptosis, autophagy, cell viability under stress, gene expression, spindle positioning, role in carbon metabolism have been discussed. In the end, I also highlighted various roles of yeasts 14-3-3 proteins in tabular form. Thus this review with primary emphasis on yeast will help in appreciating the significance of 14-3-3 proteins in cell physiology.

Hyperglycemia decreases expression of 14-3-3 proteins in an animal model of stroke

Diabetes is a severe metabolic disorder and a major risk factor for stroke. Stroke severity is worse in patients with diabetes compared to the non-diabetic population. The 14-3-3 proteins are a family of conserved acidic proteins that are ubiquitously expressed in cells and tissues. These proteins are involved in many cellular processes including metabolic pathways, signal transduction, protein trafficking, protein synthesis, and cell cycle control. This study investigated 14-3-3 proteins expression in the cerebral cortex of animals with diabetes, cerebral ischemic injury and a combination of both diabetes and cerebral ischemic injury. Diabetes was induced by intraperitoneal injection of streptozotocin (40mg/kg) in adult male rats. After 4 weeks of treatment, middle cerebral artery occlusion (MCAO) was performed for the induction of focal cerebral ischemia and cerebral cortex tissue was collected 24h after MCAO. We confirmed that diabetes increases infarct volume following MCAO compared to non-diabetic animals. In diabetic animals with MCAO injury, reduction of 14-3-3 β/α, 14-3-3 ζ/δ, 14-3-3 γ, and 14-3-3 ε isoforms was detected. The expression of these proteins was significantly decreased in diabetic animals with MCAO injury compared to diabetic-only and MCAO-only animals. Moreover, Western blot analysis ascertained the decreased expression of 14-3-3 family proteins in diabetic animals with MCAO injury, including β/α, ζ/δ, γ, ε, τ, and η isoforms. These results show the changes of 14-3-3 proteins expression in streptozotocin-induced diabetic animals with MCAO injury. Thus, these findings suggest that decreases in 14-3-3 proteins might be involved in the regulation of 14-3-3 proteins under the presence of diabetes following MCAO.

Increased 14-3-3 phosphorylation observed in Parkinson's disease reduces neuroprotective potential of 14-3-3 proteins

14-3-3 proteins are key regulators of cell survival. We have previously demonstrated that 14-3-3 levels are decreased in an alpha-synuclein (αsyn) mouse model of Parkinson's disease (PD), and that overexpression of certain 14-3-3 isoforms is protective in several PD models. Here we examine whether changes in 14-3-3 phosphorylation may contribute to the neurodegenerative process in PD. We examine three key 14-3-3 phosphorylation sites that normally regulate 14-3-3 function, including serine 58 (S58), serine 184 (S184), and serine/threonine 232 (S/T232), in several models of PD and in human PD brain. We observed that an increase in S232 phosphorylation is observed in rotenone-treated neuroblastoma cells, in cells overexpressing αsyn, and in human PD brains. Alterations in S58 phosphorylation were less consistent in these models, and we did not observe any phosphorylation changes at S184. Phosphorylation at S232 induced by rotenone is reduced by casein kinase inhibitors, and is not dependent on αsyn. Mutation of the S232 site affected 14-3-3θ's neuroprotective effects against rotenone and 1-methyl-4-phenylpyridinium (MPP(+)), with the S232D mutant lacking any protective effect compared to wildtype or S232A 14-3-3θ. The S232D mutant partially reduced the ability of 14-3-3θ to inhibit Bax activation in response to rotenone. Based on these findings, we propose that phosphorylation of 14-3-3s at serine 232 contributes to the neurodegenerative process in PD.

Changes in Brain 14-3-3 Proteins in Response to Insulin Resistance Induced by a High Palatable Diet

The 14-3-3 protein family takes part in a wide range of cellular processes and is expressed in all eukaryotic organisms. In mammals, seven isoforms (β, ε, η, γ, τ, ζ, and σ) have been identified. 14-3-3 proteins are suggested to modulate the insulin-signaling cascade in the brain. The aim of this study was to investigate whether insulin resistance state induced by high palatable diet modulates expression of the 14-3-3 proteins in brain. Wistar male rats (n = 8) were divided into two experimental groups: insulin resistant (IR), induced by high palatable diet, and control (CO) group. Biochemical parameters (glucose tolerance test and plasma lipid profile) were evaluated after 130 days. Brain structures (cortex and hippocampus) were dissected for evaluation of messenger RNA (mRNA) and protein levels of different 14-3-3 proteins. Statistical analyses included Student t test and Pearson correlation. Significant decrease was observed in Ywhah and in Ywahq mRNA levels in the cortex of IR group, while no changes were observed in the hippocampus. Significant increase of θ isoform was observed in hippocampus IR group by immunodetection, while no differences were detected in the remaining isoforms. Inverse correlation was observed between blood glucose levels in cortex IR group and both Ywhah and Ywhaq mRNA levels. Protein levels of Creb and phosphatidylinositide 3-kinases (PI3K) showed to be increased in the hippocampus. These alterations may be due to a compensatory effect of impaired insulin signaling. We demonstrated differential expression of 14-3-3 isoforms throughout brain regions of rats with IR. As a whole, our results indicate that brain 14-3-3 levels are influenced by different diets.