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SIRT6 is a modulator of chromatin structure having an important role in healthy ageing, and there is a crucial need to find specific modulators for it. Therefore, the activity of ...SIRT6 should be studied using a variety of methods. We examined the capability of SIRT6 to deacetylate a set of five fluorogenic substrates based on p53 and histone H3 sequences. The substrate designed around H3K56 deacetylation site exhibited the best signal-to-background ratio and was chosen for further studies. Nicotinamide is a known inhibitor for sirtuins, and it was found to be less potent inhibitor for SIRT6 than it is for SIRT1. In addition, we studied 15 other small molecule sirtuin modulators using the H3K56 based substrate. EX-527, quercetin and three pseudopeptidic compounds were found to be the most potent SIRT6 inhibitors, exhibiting over 50% deacetylation inhibition. These findings describe the first modulators of SIRT6 activity at the physiologically important H3K56 deacetylation site.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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l-Type amino acid transporter 1 (LAT1) is a sodium-independent exchanger transporting large neural amino acids and several amino-acid mimicking drugs across the cell membranes. LAT1 ...is highly expressed at the blood brain barrier (BBB) and in numerous cancer cells and is therefore a potential drug target. However, structural features affecting the ability to bind to LAT1 and the cellular translocation by LAT1 are unclear. In the present study we determined the binding to and transport through human LAT1 of several compounds into the human breast adenocarcinoma cells (MCF-7). We show that the meta-conjugation of l-phenylalanine increases binding to human LAT1 compared to para-conjugation or aliphatic amino acid moiety. Furthermore, large, rigid and aromatic meta-substituted l-phenylalanine derivative enabled selective and efficient LAT1-mediated cellular uptake. Our results also demonstrates that in addition to binding studies, it is of utmost importance to determine the cellular accumulation of compounds. It provides crucial information on transport efficiency and selectivity of transport mechanisms that the compounds are able to utilize. Overall, these structural findings and the methodology used herein are exploitable to design LAT1-utilizing compounds, such as markers for cancer imaging and drug molecules, enabling more effective and safer treatments for cancer in the future.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Statins are widely used in the treatment of hypercholesterolemia and are efficient in the prevention of cardiovascular disease. Molecular mechanisms explaining statin-induced impairment in insulin ...secretion remain largely unknown. In the current study, we show that simvastatin decreased glucose-stimulated insulin secretion in mouse pancreatic MIN6 β-cells by 59% and 79% (p<0.01) at glucose concentration of 5.5 mmol/l and 16.7 mmol/l, respectively, compared to control, whereas pravastatin did not impair insulin secretion. Simvastatin induced decrease in insulin secretion occurred through multiple targets. In addition to its established effects on ATP-sensitive potassium channels (p = 0.004) and voltage-gated calcium channels (p = 0.004), simvastatin suppressed insulin secretion stimulated by muscarinic M3 or GPR40 receptor agonists (Tak875 by 33%, p = 0.002; GW9508 by 77%, p = 0.01) at glucose level of 5.5 mmol/l, and inhibited calcium release from the endoplasmic reticulum. Impaired insulin secretion caused by simvastatin treatment were efficiently restored by GPR119 or GLP-1 receptor stimulation and by direct activation of cAMP-dependent signaling pathways with forskolin. The effects of simvastatin treatment on insulin secretion were not affected by the presence of hyperglycemia. Our observation of the opposite effects of simvastatin and pravastatin on glucose-stimulated insulin secretion is in agreement with previous reports showing that simvastatin, but not pravastatin, was associated with increased risk of incident diabetes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
N-Acylethanolamines Bind to SIRT6 Rahnasto-Rilla, Minna; Kokkola, Tarja; Jarho, Elina ...
Chembiochem : a European journal of chemical biology,
January 1, 2016, Volume:
17, Issue:
1
Journal Article
Peer reviewed
Open access
Sirtuin 6 (SIRT6) is an NAD+‐dependent histone deacetylase enzyme that is involved in multiple molecular pathways related to aging. Initially, it was reported that SIRT6 selectively deacetylated ...H3K9Ac and H3K56Ac; however, it has more recently been shown to preferentially hydrolyze long‐chain fatty acyl groups over acetyl groups in vitro. Subsequently, fatty acids were demonstrated to increase the catalytic activity of SIRT6. In this study, we investigated whether a series of N‐acylethanolamines (NAEs), quercetin, and luteolin could regulate SIRT6 activity. NAEs increased SIRT6 activity, with oleoylethanolamide having the strongest activity (EC50 value of 3.1 μm). Quercetin and luteolin were demonstrated to have dual functionality with respect to SIRT6 activity; namely, they inhibited SIRT6 activity with IC50 values of 24 and 2 μm, respectively, and stimulated SIRT6 activity more than sixfold (EC50 values of 990 and 270 μm, respectively).
SIRTainly novel: We have identified a series of N‐acylethanolamines as sirtuin 6 (SIRT6) activators (+) and quercetin as having dual SIRT6 activity (−/+) by using a newly developed SIRT6 H3K9Ac deacetylation assay. The involvement of sirtuins in aging, cancer, and metabolic diseases gives these compounds potential for future drug development.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Idiopathic Normal pressure hydrocephalus (iNPH) is a form of adult hydrocephalus that is clinically characterized by progressive gait impairment, cognitive dysfunction, and urinary incontinence. The ...current standard method of treatment involves surgical installation of a CSF diversion shunt. However, only a fraction of patients shows an alleviation of symptoms from shunt surgery. Thus, the purpose of this prospective explorative proteomic study was to identify prognostic CSF biomarkers to predict shunt responsiveness in iNPH patients. Further, we evaluated the ability of the core Alzheimer's disease (AD) CSF biomarkers phosphorylated (p)-tau, total (t)-tau, and amyloid-β 1-42 (Aβ
) to serve as predictors of shunt response.
We conducted a tandem mass tag (TMT) proteomic analysis of lumbar CSF from 68 iNPH patients, sampled pre-shunt surgery. Tryptic digests of CSF samples were labelled with TMTpro reagents. The TMT multiplex samples were fractionated in 24 concatenated fractions by reversed-phase chromatography at basic pH and analysed by liquid chromatography coupled to mass spectrometry (LC-MS) on an Orbitrap Lumos mass spectrometer. The relative abundances of the identified proteins were correlated with (i) iNPH grading scale (iNPHGS) and (ii) gait speed change 1 year after surgery from baseline to identify predictors of shunt responsiveness.
We identified four CSF biomarker candidates which correlated most strongly with clinical improvement on the iNPHGS and were significantly changed in shunt-responsive compared to shunt-unresponsive iNPH patients 1 year post-surgery: FABP3 (R = - 0.46, log
(fold change (FC)) = - 0.25, p < 0.001), ANXA4 (R = 0.46, log
(FC) = 0.32, p < 0.001), MIF (R = -0.49, log
(FC) = - 0.20, p < 0.001) and B3GAT2 (R = 0.54, log
(FC) = 0.20, p < 0.001). In addition, five biomarker candidates were selected based on their strong correlation with gait speed change 1 year after shunt installation: ITGB1 (R = - 0.48, p < 0.001), YWHAG (R = - 0.41, p < 0.01), OLFM2 (R = 0.39, p < 0.01), TGFBI (R = - 0.38, p < 0.01), and DSG2 (R = 0.37, p < 0.01). Concentrations of the CSF AD core biomarkers did not differ significantly with shunt responsiveness.
FABP3, MIF, ANXA4, B3GAT2, ITGB1, YWHAG, OLFM2, TGFBI and DSG2 in CSF are promising prognostic biomarker candidates to predict shunt responsiveness in iNPH patients.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
GR24 is a synthetic strigolactone analog, demonstrated to regulate the development of plants and arbuscular mycorrhizal fungi. GR24 possesses anti-cancer and anti-apoptotic properties, enhances ...insulin sensitivity and mitochondrial biogenesis in skeletal myotubes, inhibits adipogenesis, decreases inflammation in adipocytes and macrophages and downregulates the expression of hepatic gluconeogenic enzymes. Transcription factor Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) is a master regulator of antioxidant response, regulating a multitude of genes involved in cellular stress responses and anti-inflammatory pathways, thus maintaining cellular redox homeostasis. Nrf2 activation reduces the deleterious effects of mitochondrial toxins and has multiple roles in promoting mitochondrial function and dynamics. We studied the role of GR24 on gene expression in rat L6 skeletal muscle cells which were differentiated into myotubes. The myotubes were treated with GR24 and analyzed by microarray gene expression profiling. GR24 upregulated the cytoprotective transcription factor Nrf2 and its target genes, activating antioxidant defences, suggesting that GR24 may protect skeletal muscle from the toxic effects of oxidative stress.
The rare A673T variant was the first variant found within the amyloid precursor protein (APP) gene conferring protection against Alzheimer's disease (AD). Thereafter, different studies have ...discovered that the carriers of the APP A673T variant show reduced levels of amyloid beta (Aβ) in the plasma and better cognitive performance at high age. Here, we analyzed cerebrospinal fluid (CSF) and plasma of APP A673T carriers and control individuals using a mass spectrometry-based proteomics approach to identify differentially regulated targets in an unbiased manner. Furthermore, the APP A673T variant was introduced into 2D and 3D neuronal cell culture models together with the pathogenic APP Swedish and London mutations. Consequently, we now report for the first time the protective effects of the APP A673T variant against AD-related alterations in the CSF, plasma, and brain biopsy samples from the frontal cortex. The CSF levels of soluble APPβ (sAPPβ) and Aβ42 were significantly decreased on average 9–26% among three APP A673T carriers as compared to three well-matched controls not carrying the protective variant. Consistent with these CSF findings, immunohistochemical assessment of cortical biopsy samples from the same APP A673T carriers did not reveal Aβ, phospho-tau, or p62 pathologies. We identified differentially regulated targets involved in protein phosphorylation, inflammation, and mitochondrial function in the CSF and plasma samples of APP A673T carriers. Some of the identified targets showed inverse levels in AD brain tissue with respect to increased AD-associated neurofibrillary pathology. In 2D and 3D neuronal cell culture models expressing APP with the Swedish and London mutations, the introduction of the APP A673T variant resulted in lower sAPPβ levels. Concomitantly, the levels of sAPPα were increased, while decreased levels of CTFβ and Aβ42 were detected in some of these models. Our findings emphasize the important role of APP-derived peptides in the pathogenesis of AD and demonstrate the effectiveness of the protective APP A673T variant to shift APP processing towards the non-amyloidogenic pathway in vitro even in the presence of two pathogenic mutations.
•Decreased levels of sAPPβ and Aβ42 in CSF of protective APP A673T variant carriers•Cortical biopsies of APP A673T variant carriers do not show Aβ pathology•Several differentially regulated targets in CSF of APP A673T variant carriers•APP A673T variant lowers sAPPβ levels in 2D and 3D cell culture models of AD
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Heat shock proteins (HSPs), originally identified as heat-inducible gene products, are a family of highly conserved proteins that respond to a wide variety of stress including oxidative stress. ...Although both acute and chronic oxidative stress have been well demonstrated to induce HSP responses, little evidence is available whether increased HSP levels provide enhanced protection against oxidative stress under elevated yet sublethal temperatures. We studied relationships between oxidative stress and HSPs in a physiological model by using Garra rufa (doctor fish), a fish species naturally acclimatized to different thermal conditions. We compared fish naturally living in a hot spring with relatively high water temperature (34.4±0.6°C) to those living in normal river water temperature (25.4±4.7°C), and found that levels of all the studied HSPs (HSP70, HSP60, HSP90, HSC70 and GRP75) were higher in fish living in elevated water temperature compared with normal river water temperature. In contrast, indicators of oxidative stress, including protein carbonyls and lipid hydroperoxides, were decreased in fish living in the elevated temperature, indicating that HSP levels are inversely associated with oxidative stress. The present results provide evidence that physiologically increased HSP levels provide protection against oxidative stress and enhance cytoprotection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aims/hypothesis
It is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The ...previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1:
N
≤ 920) or with recently diagnosed type 2 diabetes (cohort 2:
N
≤ 435).
Methods
We defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and
p
values, respectively.
Results
The TC and TC-PA models showed better fit than null models (TC: χ
2
= 242,
p
= 0.004 and χ
2
= 63,
p
= 0.001 in cohort 1 and 2, respectively; TC-PA: χ
2
= 180,
p
= 0.041 and χ
2
= 60,
p
= 0.008 in cohort 1 and 2, respectively). The association of physical activity with glycaemic control was primarily mediated by variables in the liver fat cycle.
Conclusions/interpretation
These analyses partially support the mechanisms proposed in the twin-cycle model and highlight mechanistic pathways through which insulin sensitivity and liver fat mediate the association between physical activity and glycaemic control.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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