Enzymatic Regulation of Protein-Protein Interactions in Artificial Cells

Membraneless organelles are important for spatial organization of proteins and regulation of intracellular processes. Proteins can be recruited to these condensates by specific protein–protein or protein–nucleic acid interactions, which are often regulated by post-translational modifications. However, the mechanisms behind these dynamic, affinity-based protein recruitment events are not well understood. Here, a coacervate system that incorporates the 14-3-3 scaffold protein to study enzymatically regulated recruitment of 14-3-3-binding proteins is presented, which mostly bind in a phosphorylation-dependent manner. Synthetic coacervates are efficiently loaded with 14-3-3, and phosphorylated binding partners, such as the c-Raf pS233/pS259 peptide (c-Raf), show 14-3-3-dependent sequestration with up to 161-fold increase in local concentration. The c-Raf domain is fused to green fluorescent protein (GFP-c-Raf) to demonstrate recruitment of proteins. In situ phosphorylation of GFP-c-Raf by a kinase leads to enzymatically regulated uptake. The introduction of a phosphatase into coacervates preloaded with the phosphorylated 14-3-3-GFP-c-Raf complex results in a significant cargo efflux mediated by dephosphorylation. Finally, the general applicability of this platform to study protein–protein interactions is demonstrated by the phosphorylation-dependent and 14-3-3-mediated active reconstitution of a split-luciferase inside artificial cells. This work presents an approach to study dynamically regulated protein recruitment in condensates, using native interaction domains.</p

Effects of Eprosartan on Diastolic Function and Neurohormones in Patients with Hypertension and Diastolic Dysfunction

To compare the effects of an angiotensin receptor blocker(ARB)-based regimen versus a non-ARB based regimen on diastolic function and neurohormones in patients with hypertension and diastolic dysfunction. 97 patients with a systolic blood pressure (SBP) a parts per thousand yen140 mmHg, a left ventricular ejection fraction > 0.50, and echocardiographic evidence of diastolic dysfunction were randomly assignment to open-label treatment with eprosartan (with other anti-hypertensives; n = 47) or other anti-hypertensives alone (n = 50). Echocardiography, including tissue Doppler imaging (TDI), and neurohormones were done at baseline and after 6 months. Mean age was 65 (+/- 10) years and 64% was female. During 6 months of treatment, SBP decreased from 157 +/- 16 to 145 +/- 18 mmHg in the eprosartan group and from 158 +/- 17 to 141 +/- 18 mmHg in the control group (both p <0.001; p = ns between groups). Diastolic function was unaffected in both groups and there was no correlation between changes in SBP and changes in mean TDI (r = -0.06; p = 0.58). Aldosterone levels decreased in the eprosartan group, but other neurohormones remained largely unchanged. Change in SBP was however related to the change in NT-proBNP (r = 0.26; p = 0.019). Lowering blood pressure, either with eprosartan or other anti-hypertensives in hypertensive patients with diastolic dysfunction did not change diastolic function after 6 months of treatment, but was associated with a decrease of NT-proBNP

Uniquely sized nanogels via crosslinking polymerization

Nanogels are very promising carriers for nanomedicine, as they can be prepared in the favorable nanometer size regime, can be functionalized with targeting agents and are responsive to stimuli, i.e. temperature and pH. This induces shrinking or swelling, resulting in controlled release of a therapeutic cargo. Our interest lies in the controlled synthesis of functional nanogels, such as those containing epoxide moieties, that can be subsequently functionalized. Co-polymerization of glycidyl methacrylate and a bifunctional methacrylate crosslinker under dilute conditions gives rise to well-defined epoxide-functional nanogels, of which the sizes are controlled by the degree of polymerization. Nanogels with well-defined sizes (polydispersity of 0.2) ranging from 38 nm to 95 nm were prepared by means of controlled radical polymerization. The nanogels were characterized in detail by FT-IR, DLS, size exclusion chromatography, NMR spectroscopy, AFM and TEM. Nucleophilic attack with functional thiols or amines on the least hindered carbon of the epoxide provides water-soluble nanogels, without altering the backbone structure, while reaction with sodium azide provides handles for further functionalization via click chemistry

Advanced glycation end-products, anti-hypertensive treatment and diastolic function in patients with hypertension and diastolic dysfunction

Aims To investigate the relationship between advanced glycation end-products (AGEs) and diastolic function and the response to blood pressure treatment in patients with hypertension and diastolic dysfunction. Methods and results Data were analysed from 97 patients (aged 65 +/- 10 years, 36% male) who were randomly assigned to 6 months open-label treatment with either eprosartan on top of other anti-hypertensive drugs (n = 47) or other antihypertensive drugs alone (n = 50). Tissue AGE accumulation was measured using a validated skin-autofluorescence (skin-AF) reader (n = 26). Plasma N(epsilon)-(carboxymethyl) lysine (CML), N(epsilon)-(carboxyethyl) lysine (CEL), and pentosidine were measured by LC-MS/MS and HPLC. Diastolic function was assessed using echocardiography. Blood pressure was reduced from 157/91 to 145/84 mmHg (P median, E/A ratio (P = 0.84) and mean E' (P = 0.32) remained unchanged. Conclusion Although eprosartan did not decrease levels of AGEs, patients with lower skin-AF at baseline showed a larger improvement in diastolic function in response to either anti-hypertensive treatment compared with patients with higher skin-AF

Predictors of angiotensin-converting enzyme inhibitor - Induced reduction of urinary albumin excretion in nondiabetic patients

Urinary albumin excretion is a predictor for cardiovascular mortality and morbidity. We investigated which parameters determine baseline urinary albumin excretion in nondiabetic subjects, without renal disease. In addition, we evaluated the parameters that predict the albuminuria-lowering efficacy of an angiotensin-converting enzyme inhibitor. In this substudy of the Prevention of Renal and Vascular Endstage Disease Intervention Trial, 384 microalbuminuric patients were included. Patient and biochemical characteristics were obtained at baseline and after 3 months of double-blinded, randomized treatment (fosinopril 20 mg or placebo). Mean age was 51.1 +/- 11.5 years, and 65.6% were male. Median urinary albumin excretion was 22.2 mg per 24 hours. At baseline, mean arterial pressure (beta(standardized) = 0.161; P = 0.006), urinary sodium excretion (beta(standardized) = 0.154; P = 0.011), and estimated renal function were independently associated with albumin excretion. In these predominantly normotensive to prehypertensive subjects, fosinopril reduced albumin excretion by 18.5% versus a 6.1% increase on placebo after 3 months (P <0.001). Fosinopril use and blood pressure reduction independently predicted the change in urinary albumin excretion. Baseline urinary albumin excretion independently predicted the antialbuminuric effect of fosinopril (beta(standardized) = -0.303; P <0.001). In conclusion, at baseline, sodium intake and blood pressure were positively associated with urinary albumin excretion. Fosinopril reduced albuminuria more than might be expected from its blood pressure - lowering effect alone, and this effect was more outspoken in subjects with higher baseline albumin excretion. Based on our data, we hypothesize that angiotensin-converting enzyme inhibition may result in superior cardiovascular protection when compared with other blood pressure-lowering agents in subjects with higher baseline levels of albuminuria