Prediction of acute kidney injury in patients with liver cirrhosis using machine learning models: evidence from the MIMIC-III and MIMIC-IV.

PURPOSE: To develop and validate a machine learning (ML)-based prediction model for acute kidney injury (AKI) in patients with liver cirrhosis. METHODS: Data on liver cirrhosis patients were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) and MIMIC-IV databases in this retrospective cohort study. ML algorithms, including random forest (RF), extreme gradient boosting (XGB), light gradient boosting machine (LGBM), and gradient boosting decision tree (GBDT) were applied to construct prediction models. Predictors were screened via univariate logistic regression, and then the models were developed with all data of the included patients. A bootstrap resampling method was adopted to validate the models. The predictive abilities of our final model were compared with those of the sequential organ failure assessment score (SOFA), simplified acute physiology score II (SAPS II), Model for End-stage Liver Disease (MELD), and MELD Na. RESULTS: This study included 950 patients, of which 429 (45.16%) had AKI. Mechanical ventilation, vasopressor, international normalized ratio (INR), bilirubin, Charlson comorbidity index (CCI), prothrombin time (PT), estimated glomerular filtration rate (EGFR), partial thromboplastin time (PTT), and heart rate served as predictors. In the derivation set, the developed RF [area under curve (AUC) = 0.747], XGB (AUC = 0.832), LGBM (AUC = 0.785), and GBDT (AUC = 0.811) models exhibited significantly greater predictive performance than the logistic regression model (AUC = 0.699) (all P < 0.05). Among the ML-based models, the XGB model had the greatest AUC. In internal validation, the predictive capacity of the XGB model (AUC = 0.833) was significantly superior to that of the logistic regression model (AUC = 0.701) (P = 0.045). Hence, the XGB model was selected as the final model for AKI prediction. In contrast to the XGB model (AUC = 0.832), the SOFA (AUC = 0.609), MELD (AUC = 0.690), MELD Na (AUC = 0.690), and SAPS II (AUC = 0.641) had significantly lower predictive abilities in the derivation set (all P < 0.001). The XGB model was internally validated to have an AUC of 0.833, which was significantly higher than the SOFA (AUC = 0.609), MELD (AUC = 0.690), MELD Na (AUC = 0.688), and SAPS II (AUC = 0.641) (all P < 0.05). CONCLUSION: The XGB model had a better performance than the logistic regression model, SOFA, MELD, MELD Na, and SAPS II in AKI prediction for cirrhosis patients, which may help identify patients at a risk of AKI, and then provide timely interventions.

Bidirectional control of parathyroid hormone and bone mass by subfornical organ.

Parathyroid hormone (PTH) is one of the most important hormones for bone turnover and calcium homeostasis. It is unclear how the central nervous system regulates PTH. The subfornical organ (SFO) lies above the third ventricle and modulates body fluid homeostasis. Through retrograde tracing, electrophysiology, and in vivo calcium imaging, we identified the SFO as an important brain nucleus that responds to serum PTH changes in mice. Chemogenetic stimulation of GABAergic neurons in SFO induces decreased serum PTH followed by a decrease in trabecular bone mass. Conversely, stimulation of glutamatergic neurons in the SFO promoted serum PTH and bone mass. Moreover, we found that the blockage of different PTH receptors in the SFO affects peripheral PTH levels and the PTH's response to calcium stimulation. Furthermore, we identified a GABAergic projection from the SFO to the paraventricular nucleus, which modulates PTH and bone mass. These findings advance our understanding of the central neural regulation of PTH at cellular and circuit level.

NUF2 overexpression contributes to epithelial ovarian cancer progression via ERBB3-mediated PI3K-AKT and MAPK signaling axes.

Introduction: NDC80 kinetochore complex component (NUF2) is upregulated and plays an important role in various human cancers. However, the function and mechanism of NUF2 in epithelial ovarian cancer (EOC) remain unclear. Methods: NUF2 expression was detected in EOC tissues and cell lines. The effects of NUF2 downregulation on cell proliferation, migration and invasion in EOC were analyzed by CCK-8 and Transwell assays. Meanwhile, the effect of NUF2 downregulation on tumor growth in vivo was determined by xenograft tumor models. The mechanisms by which NUF2 regulates EOC progression were detected by RNA sequencing and a series of in vitro assays. Results: We showed that NUF2 was significantly upregulated in EOC tissues and cell lines, and high NUF2 expression was associated with FIGO stage, pathological grade and poor EOC prognosis. NUF2 downregulation decreased cell proliferation, migration, invasion and tumor growth in nude mice. RNA sequencing studies showed that NUF2 knockdown inhibited several genes enriched in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)-AKT serine/threonine kinase (AKT) and mitogen-activated protein kinase (MAPK) signaling pathways. Erb-B2 receptor tyrosine kinase 3 (ERBB3) was the key factor involved in both of the above pathways. We found that ERBB3 silencing could inhibit EOC progression and repress activation of the PI3K-AKT and MAPK signaling pathways. Furthermore, the exogenous overexpression of ERBB3 partially reversed the inhibitory effects on EOC progression induced by NUF2 downregulation, while LY294002 and PD98059 partially reversed the effects of ERBB3 upregulation. Conclusion: These results showed that NUF2 promotes EOC progression through ERBB3-induced activation of the PI3K-AKT and MAPK signaling axes. These findings suggest that NUF2 might be a potential therapeutic target for EOC.

NOL6 promotes the proliferation and migration of endometrial cancer cells by regulating TWIST1 expression.

Aim: To investigate the role and function of NOL6, a protein related to ribosome biogenesis, in endometrial cancer. Methods: Methyl thiazolyl tetrazolium assay, colony formation assay, flow cytometry apoptosis assay, transwell assay and wound healing assays were carried out for evaluating cell proliferation, migration and apoptosis. Immunohistochemistry, western blot and tumor xenograft assays were carried out for detecting the level of protein expression and tumor formation. Results: We demonstrated that NOL6 is overexpressed in endometrial cancer and promotes cell proliferation and migration while reducing apoptosis. NOL6 regulates the expression of TWIST1, which can restore the changes in cells caused by NOL6 knockdown. Conclusions: NOL6 can promote the proliferation and migration of endometrial cancer cells by regulating TWIST1 expression.

Lay abstract In endometrial cancer, rapid tumor growth leads to increased protein synthesis and ribosome biogenesis. Our study confirmed the involvement of the protein NOL6 in endometrial cancer. We overexpressed TWIST1, MMP2 or MYC in endometrial cells and assessed the difference in cell growth, spread, death and tumor formation under different conditions. The results showed that NOL6 can boost the growth and spread of endometrial cancer cells by controlling TWIST1 expression. Our study provides a new understanding of the molecular mechanisms causing endometrial cancer.

Alkaloid leonurine exerts anti-inflammatory effects via modulating MST1 expression in trophoblast cells.

BACKGROUND: Pre-eclampsia (PE) is mainly attributed to the inflammation of trophoblast cells in pregnant women, which results in damage to the maternal organs and growth retardation of the fetus. Alkaloid leonurine (LNR) is a plant compound and has anti-inflammatory effects. Here we aimed to investigate the effects of LNR on human and mouse trophoblast cells and the underlying mechanisms. METHODS: The levels of the inflammatory factors in trophoblast cells under lipopolysaccharides (LPS) stimulation were analyzed with ELISA. Western blot was employed to examine the protein expression. Trophoblast cells in Mammalian ste20-like kinase 1 (MST1-/- ) or wild type (WT) mice were isolated to examine the expression of signal molecules in the nuclear factor-κB (NF-κB) pathway. Concentration-dependent activity of NF-κB was examined. The regulation of LNR and MST1 in MST1-/- trophoblast cells was studied as well. RESULTS: Our data showed that LNR exhibited anti-inflammatory effects and suppressed the NF-κB signaling by inhibiting LPS-induced inflammation in trophoblast cells. LNR upregulated the expression of MST1, and the anti-inflammatory role of LNR was greatly relieved in MST1-knockout trophoblast cells, although it displayed weak roles in NF-κB signaling. CONCLUSION: LNR exhibits anti-inflammatory effects on human and mouse trophoblast cells by upregulating MST1 in the NF-κB signal pathway.

Inhibiting USP14 ameliorates inflammatory responses in trophoblast cells by suppressing MAPK/NF-κB signaling.

BACKGROUND: Preeclampsia can cause severe consequences for pregnant women and infants, and developing effective medicine or methods to prevent or treat patients with preeclampsia is urgently needed. Ubiquitin-specific protease 14 (USP14) has emerged as a critical regulator in the development of human cancers and neurodegenerative diseases. However, its role in preeclampsia remains elusive. METHODS: The expression of USP14 in placental tissues from healthy donors and preeclampsia patients were determined by quantitative reverse transcription PCR assay. The protein levels of targeted genes were evaluated by Western blotting assay. Small interfering RNA-mediated gene knockdown was used to reduce USP14 expression in trophoblast cell lines. RESULTS: The expression levels of USP14 and proinflammatory cytokine were substantially upregulated in placental tissues from preeclampsia patients. Knockdown or inhibition of USP14 significantly abrogated hypoxia/reoxygenation-induced upregulation of nuclear factor kappa B (NF-κB) activation and proinflammatory cytokine production. CONCLUSION: Our results suggested that USP14 promotes proinflammatory cytokine production through activation of NF-κB. Developing drugs targeting USP14 may be beneficial for the prevention or treatment of patients with preeclampsia.

Plasma irisin levels are associated with hemodynamic and clinical outcome in idiopathic pulmonary arterial hypertension patients.

Irisin has been considered to reflect oxidative stress. This study aimed to show whether plasma irisin levels are correlated with hemodynamic dysfunction and predict the clinical outcome of patients with idiopathic pulmonary arterial hypertension (IPAH). A total of 68 adult IPAH patients were prospectively recruited in the present study. Plasma irisin levels were measured by the ELISA method in enrolled IPAH patients. Baseline clinical characteristics, and hemodynamic and clinical outcome were compared according to different plasma irisin levels. IPAH patients were divided into high irisin group (irisin ≥ 7.3 µg/ml) and low irisin group (irisin < 7.3 µg/ml) according to median values of irisin levels. Total plasma cholesterol levels (P = 0.027) and low-density lipoprotein cholesterol (LDL-C) levels (P = 0.042) were higher in high irisin group and were positively correlated with plasma irisin levels. IPAH patients in low irisin group had a significantly higher mean pulmonary artery pressure (mPAP, P = 0.047), systolic pulmonary artery pressure (sPAP, P = 0.022), systolic right-ventricular pressure (sRVP, P = 0.007), mean right atrial pressure (mRAP, P = 0.043), and systolic right atrial pressure (sRAP, P = 0.020). mRAP, sRAP, and diastolic right atrial pressure (dRAP) were negatively correlated with plasma irisin levels. Low irisin group predicts adverse hemodynamic status and poor free of event survival rate (P = 0.030, log-rank test). Multivariate analysis indicates plasma irisin levels to be an independent predictor of prognosis in IPAH patients after adjusting for related covariates (HR 0.786; 95% CI 0.584, 0.957; P = 0.038). Plasma irisin levels may serve as a novel biomarker in IPAH patients for hemodynamic severity assessment and clinical outcome evaluation.

Plasma irisin level associated with hemodynamic parameters and predict clinical outcome in patients with acute pulmonary embolism.

BACKGROUND: The purpose of the present study is to investigate the correlation of plasma irisin level and hemodynamic parameters in patients with acute pulmonary embolism (APE) and to estimate clinical outcome prediction value of plasma irisin level. METHODS: We prospectively recruited 86 adult patients with APE in the present study. All recruited patients conduct measurement of plasma irisin levels using ELISA kits. Baseline clinical characteristics, hemodynamic parameters and prognostic conditions were evaluated according to different plasma irisin levels. RESULTS: According to median values of irisin levels, APE patients were divided into high irisin group (irisin≥6.9 µg/ml) and low irisin group (irisin<6.9 µg/ml). Plasma NT-proBNP (P = 0.044), mean pulmonary artery pressure (mPAP, P = 0.013), systolic pulmonary artery pressure (sPAP, P = 0.001), mean right ventricular pressure (mRVP, P = 0.021) and systolic right ventricular pressure (sPVP, P = 0.003) were higher in low irisin group compared with high irisin group. Hemodynamic parameters of mPAP, sPAP, mRVP and sRVP were negatively correlated with plasma irisin levels. Kaplan- Meier survival analysis showed that APE patients with lower plasma irisin levels had significantly higher clinical worsening event rate (P = 0.026) and could be the independent predictor of prognosis in multivariate analysis (P = 0.035). CONCLUSION: Plasma irisin level was negatively correlated with hemodynamic parameters in patients with APE. Low irisin group patients had significantly higher clinical worsening event rate and could be the independent predictor of clinical outcome in multivariate analysis.

Thirty Years of Saying NO: Sources, Fate, Actions, and Misfortunes of the Endothelium-Derived Vasodilator Mediator.

Endothelial cells control vascular tone by releasing nitric oxide (NO) produced by endothelial NO synthase. The activity of endothelial NO synthase is modulated by the calcium concentration and by post-translational modifications (eg, phosphorylation). When NO reaches vascular smooth muscle, soluble guanylyl cyclase is its primary target producing cGMP. NO production is stimulated by circulating substances (eg, catecholamines), platelet products (eg, serotonin), autacoids formed in (eg, bradykinin) or near (eg, adiponectin) the vascular wall and physical factors (eg, shear stress). NO dysfunction can be caused, alone or in combination, by abnormal coupling of endothelial cell membrane receptors, insufficient supply of substrate (l-arginine) or cofactors (tetrahydrobiopterin), endogenous inhibitors (asymmetrical dimethyl arginine), reduced expression/presence/dimerization of endothelial NO synthase, inhibition of its enzymatic activity, accelerated disposition of NO by reactive oxygen species and abnormal responses (eg, biased soluble guanylyl cyclase activity producing cyclic inosine monophosphate) of the vascular smooth muscle. Major culprits causing endothelial dysfunction, irrespective of the underlying pathological process (aging, obesity, diabetes mellitus, and hypertension), include stimulation of mineralocorticoid receptors, activation of endothelial Rho-kinase, augmented presence of asymmetrical dimethyl arginine, and exaggerated oxidative stress. Genetic and pharmacological interventions improve dysfunctional NO-mediated vasodilatations if protecting the supply of substrate and cofactors for endothelial NO synthase, preserving the presence and activity of the enzyme and reducing reactive oxygen species generation. Common achievers of such improvement include maintained levels of estrogens and increased production of adiponectin and induction of silent mating-type information regulation 2 homologue 1. Obviously, endothelium-dependent relaxations are not the only beneficial action of NO in the vascular wall. Thus, reduced NO-mediated responses precede and initiate the atherosclerotic process.

Vascular nitric oxide: Beyond eNOS.

As the first discovered gaseous signaling molecule, nitric oxide (NO) affects a number of cellular processes, including those involving vascular cells. This brief review summarizes the contribution of NO to the regulation of vascular tone and its sources in the blood vessel wall. NO regulates the degree of contraction of vascular smooth muscle cells mainly by stimulating soluble guanylyl cyclase (sGC) to produce cyclic guanosine monophosphate (cGMP), although cGMP-independent signaling [S-nitrosylation of target proteins, activation of sarco/endoplasmic reticulum calcium ATPase (SERCA) or production of cyclic inosine monophosphate (cIMP)] also can be involved. In the blood vessel wall, NO is produced mainly from l-arginine by the enzyme endothelial nitric oxide synthase (eNOS) but it can also be released non-enzymatically from S-nitrosothiols or from nitrate/nitrite. Dysfunction in the production and/or the bioavailability of NO characterizes endothelial dysfunction, which is associated with cardiovascular diseases such as hypertension and atherosclerosis.

α1 -Adrenoceptor activation of PKC-ε causes heterologous desensitization of thromboxane receptors in the aorta of spontaneously hypertensive rats.

BACKGROUND AND PURPOSE: In the aorta of adult spontaneously hypertensive (SHR), but not in that of normotensive Wistar-Kyoto (WKY), rats, previous exposure to phenylephrine inhibits subsequent contractions to PGE2 . The present experiments were designed to examine the mechanism(s) underlying this inhibition. EXPERIMENTAL APPROACH: Isometric tension was measured in isolated rings of SHR and WKY aortae. Gene expression and protein presence were measured by quantitative real-time PCR and Western blotting respectively. KEY RESULTS: In aorta of 18 weeks SHR, but not age-matched WKY, pre-exposure to phenylephrine inhibited subsequent contractions to PGE2 that were mediated by thromboxane prostanoid (TP) receptors. This inhibition was not observed in preparations of pre-hypertensive 5-week-old SHR, and was significantly larger in those of 36- than 18-week-old SHR. Pre-exposure to the PKC activator, phorbol 12,13-dibutyrate, also inhibited subsequent contractions to PGE2 in SHR aortae. The selective inhibitor of PKC-ε, ε-V1-2, abolished the desensitization caused by pre-exposure to phenylephrine. Two molecular PKC bands were detected and their relative intensities differed in 36-week-old WKY and SHR vascular smooth muscle. The mRNA expressions of PKC-α, PKC-ε, PK-N2 and PKC-ζ and of G protein-coupled kinase (GRK)-2, GRK4 and ß-arrestin2 were higher in SHR than WKY aortae. CONCLUSIONS AND IMPLICATIONS: These experiments suggest that in the SHR but not the WKY aorta, α1 -adrenoceptor activation desensitizes TP receptors through activation of PKC-ε. This heterologous desensitization is a consequence of the chronic exposure to high arterial pressure.

Elevated pressure causes endothelial dysfunction in mouse carotid arteries by increasing local angiotensin signaling.

Experiments were performed to determine whether or not acute exposure to elevated pressure would disrupt endothelium-dependent dilatation by increasing local angiotensin II (ANG II) signaling. Vasomotor responses of mouse-isolated carotid arteries were analyzed in a pressure myograph at a control transmural pressure (PTM) of 80 mmHg. Acetylcholine-induced dilatation was reduced by endothelial denudation or by inhibition of nitric oxide synthase (NG-nitro-L-arginine methyl ester, 100 µM). Transient exposure to elevated PTM (150 mmHg, 180 min) inhibited dilatation to acetylcholine but did not affect responses to the nitric oxide donor diethylamine NONOate. Elevated PTM also increased endothelial reactive oxygen species, and the pressure-induced endothelial dysfunction was prevented by the direct antioxidant and NADPH oxidase inhibitor apocynin (100 µM). The increase in endothelial reactive oxygen species in response to elevated PTM was reduced by the ANG II type 1 receptor (AT1R) antagonists losartan (3 µM) or valsartan (1 µM). Indeed, elevated PTM caused marked expression of angiotensinogen, the precursor of ANG II. Inhibition of ANG II signaling, by blocking angiotensin-converting enzyme (1 µM perindoprilat or 10 µM captopril) or blocking AT1Rs prevented the impaired response to acetylcholine in arteries exposed to 150 mmHg but did not affect dilatation to the muscarinic agonist in arteries maintained at 80 mmHg. After the inhibition of ANG II, elevated pressure no longer impaired endothelial dilatation. In arteries treated with perindoprilat to inhibit endogenous formation of the peptide, exogenous ANG II (0.3 µM, 180 min) inhibited dilatation to acetylcholine. Therefore, elevated pressure rapidly impairs endothelium-dependent dilatation by causing ANG expression and enabling ANG II-dependent activation of AT1Rs. These processes may contribute to the pathogenesis of hypertension-induced vascular dysfunction and organ injury.

Reproducibility of quantitative real-time PCR assay in microRNA expression profiling and comparison with microarray analysis in narcolepsy.

MicroRNAs (miRNAs) have been shown in the pathogenesis of human neurological disorders. The study aims to identify the involvement of miRNAs in the pathophysiology of narcolepsy. Here, we conducted three independent high-throughput analysis of miRNA (miRNA microarray) in peripheral blood from 20 narcolepsy patients who fulfilled the criteria compared to 20 healthy controls with validation experiment using quantitative real-time polymerase chain reaction (real-time PCR) panels. By analyzing 2805 miRNAs in peripheral blood with microarray we identified 128 miRNAs (105 high expression and 23 low expression) that were different in patients with narcolepsy in comparison with healthy control. Then we chose six high expression candidates and six low expression candidates of at least twofold difference and p value < 0.05 to validate the changes in three independent experiments in vitro using real-time PCR. The validation test showed that levels of hsa-mir-1267, hsa-miR-4309, hsa-miR-554, hsa-miR-1272, hsa-miR-4501, hsa-miR-182-3p were higher, whereas the level of hsa-miR-625-5p, hsa-miR-100-5p, hsa-miR-125b-5p, hsa-miR-197-3p, hsa-miR-4522, hsa-miR-493-5p was lower in narcolepsy patients than healthy controls. The levels of 12 miRNAs differed significantly in peripheral blood from narcolepsy patients which suggested that alterations of miRNAs expression may be involved in the pathophysiology of narcolepsy.

A-FABP and oxidative stress underlie the impairment of endothelium-dependent relaxations to serotonin and the intima-medial thickening in the porcine coronary artery with regenerated endothelium.

Experiments were designed to determine the cause of the selective dysfunction of G(i) proteins, characterized by a reduced endothelium-dependent relaxation to serotonin (5-hydroxytryptamine), in coronary arteries lined with regenerated endothelial cells. Part of the endothelium of the left anterior descending coronary artery of female pigs was removed in vivo to induce regeneration. The animals were treated chronically with vehicle (control), apocynin (antioxidant), or BMS309403 (A-FABP inhibitor) for 28 days before functional examination and histological analysis of segments of coronary arteries with native or regenerated endothelium of the same hearts. Isometric tension was recorded in organ chambers and cumulative concentration-relaxation curves obtained in response to endothelium-dependent [serotonin (G(i) protein mediated activation of eNOS) and bradykinin (G(q) protein mediated activation of eNOS)] and independent [detaNONOate (cGMP-mediated), isoproterenol (cAMP-mediated)] vasodilators. The two inhibitors tested did not acutely affect relaxations of preparations with either native or regenerated endothelium. In the chronically treated groups, however, both apocynin and BMS309403 abolished the reduction in relaxation to serotonin in segments covered with regenerated endothelium and prevented the intima-medial thickening caused by endothelial regeneration, without affecting responses to bradykinin or endothelium-independent agonists (detaNONOate and isoproterenol). Thus, inhibition of either oxidative stress or A-FABP likely prevents both the selective dysfunction of G(i) protein mediated relaxation to serotonin and the neointimal thickening resulting from endothelial regeneration.

Endothelial nitric oxide synthase-independent release of nitric oxide in the aorta of the spontaneously hypertensive rat.

In the aorta of male spontaneously hypertensive rats (SHR), but not in that of normotensive Wistar-Kyoto rats (WKY), contractions to phenylephrine obtained in the presence of L-NAME [inhibitor of nitric oxide synthase (NOS)] and indomethacin (inhibitor of cyclooxygenase) are inhibited by an unknown endothelium-derived factor. The present study aimed to identify the mechanism underlying this endothelium-dependent inhibition in the SHR aorta. Aortic rings of male SHR and WKY, with and without endothelium, were suspended in organ chambers in the presence of indomethacin and L-NAME for the measurement of isometric tension. Contractions to phenylephrine were smaller in SHR aortae with endothelium than in those without, but were similar in the two types of preparations of WKY aortae. The endothelium-dependent, NOS-independent inhibition of phenylephrine-induced contraction was abolished by oxyhemoglobin [extracellular NO scavenger], carboxy-PTIO (NO scavenger) and ODQ (inhibitor of soluble guanylyl cyclase). It was unmasked not only by indomethacin but also by apocynin (antioxidant), but inhibited by diphenyleneiodonium (inhibitor of flavoproteins including cytochrome P450 reductase). The cytochrome P450 reductase protein expression was similar in SHR and WKY aortae. However, the level of nitrate and nitrite, substrates of cytochrome P450 reductase, were higher in SHR than WKY plasma and aortae. Therefore, in SHR but not WKY aortae, eNOS-independent NO is formed by cytochrome P450 reductase.

Collagen type IV-specific tripeptides for selective adhesion of endothelial and smooth muscle cells.

Controlling the balance of endothelial cells (ECs) and smooth muscle cells (SMCs) in blood vessels is critically important to minimize the risk associated with vascular implants. Extracellular matrix (ECM) plays a key role in controlling the cellular balance, suggesting a promising source of cell-selective peptides. To obtain EC- or SMC-selective peptides, we start by highlighting sequence differences found among ECM molecules as enriched targets for cell-selective peptides. We explored the EC- or SMC-selective performance of tripeptides that are specifically enriched only in collagen type IV, but not in types I, II, III, and V. Collagen type IV was chosen since it is the major ECM in the basement membrane of blood vessels, which separates ECs and SMCs. Among 114 collagen type IV-derived tripeptides pre-screened from in silico analysis, 22 peptides (19%) were found to promote cell-selective adhesion, as determined by peptide array. One of the best performing EC-selective peptides (Cys-Ala-Gly (CAG)) was mixed into an electrospun fine-fiber, a vascular graft material, for practical application. Compared to unmodified fiber, the CAG containing fiber surface was found to enhance adhesion of ECs (+190%) while limiting SMCs (-20%). These results are not only consistent with the hypothesis of ECM as a source of cell selective peptides, but also suggest a new genre of EC- or SMC-selective peptides for tissue engineering applications. Collectively, these findings favorably support the screening approach used to discover new peptides for these purposes.

Amino acid sequence preferences to control cell-specific organization of endothelial cells, smooth muscle cells, and fibroblasts.

Effective surface modification with biocompatible molecules is known to be effective in reducing the life-threatening risks related to artificial cardiovascular implants. In recent strategies in regenerative medicine, the enhancement and support of natural repair systems at the site of injury by designed biocompatible molecules have succeeded in rapid and effective injury repair. Therefore, such a strategy could also be effective for rapid endothelialization of cardiovascular implants to lower the risk of thrombosis and stenosis. To achieve this enhancement of the natural repair system, a biomimetic molecule that mimics proper cellular organization at the implant location is required. In spite of the fact that many reported peptides have cell-attracting properties on material surfaces, there have been few peptides that could control cell-specific adhesion. For the advanced cardiovascular implants, peptides that can mimic the natural mechanism that controls cell-specific organization have been strongly anticipated. To obtain such peptides, we hypothesized the cellular bias toward certain varieties of amino acids and examined the cell preference (in terms of adhesion, proliferation, and protein attraction) of varieties and of repeat length on SPOT peptide arrays. To investigate the role of specific peptides in controlling the organization of various cardiovascular-related cells, we compared endothelial cells (ECs), smooth muscle cells (SMCs), and fibroblasts (FBs). A clear, cell-specific preference was found for amino acids (longer than 5-mer) using three types of cells, and the combinational effect of the physicochemical properties of the residues was analyzed to interpret the mechanism.

Characterization of the Haloarcula hispanica amyH gene promoter, an archaeal promoter that confers promoter activity in Escherichia coli.

Archaea form a third domain of life that is distinct from Bacteria and Eukarya. According to the current knowledge, the basal transcription machinery of Archaea (including the core promoter architecture, the RNA polymerase, and the basal transcription factors) closely resembles that of Eukarya in structure and function, while differing considerably from the bacterial paradigm. In the present study, the promoter region of the halophilic archaeon Haloarcula hispanica's amyH gene was isolated and characterized, and it was surprisingly revealed that the amyH gene promoter could confer promoter activity (i.e., drive transcription) in haloarchaea (Archaea) as well as in Escherichia coli (Bacteria), where the transcriptions driven are initiated at the same adenine base. Further investigation revealed that the core structure of the amyH gene promoter possesses a combination of the typical structural characteristics of archaeal promoter, which are eukaryotic-like, and those of bacterial promoter. Our results indicate that the core promoter structures of some archaeal genes may possess a combination of eukaryotic- and bacterial-like features, and moreover, suggest a possible evolutionary relationship between basal transcription signals and transcription mechanisms of Archaea and the other two domains of life.