Enzymatic Synthesis of Disialyllacto-N-Tetraose (DSLNT) and Related Human Milk Oligosaccharides Reveals Broad Siglec Recognition of the Atypical Neu5Acα2-6GlcNAc Motif.

Sialic acids (Sias) are ubiquitously expressed on all types of glycans, typically as terminating residues. They usually link to galactose, N-acetylgalactosamine, or other Sia residues, forming ligands of many glycan-binding proteins. An atypical linkage to the C6 of N-acetylglucosamine (GlcNAc) has been identified in human milk oligosaccharides (HMOs, e.g., DSLNT) and tumor-associated glycoconjugates. Herein, describe the systematic synthesis of these HMOs in an enzymatic modular manner. The synthetic strategy relies on a novel activity of ST6GalNAc6 for efficient construction of the Neu5Acα2-6GlcNAc linkage, and another 12 specific enzyme modules for sequential HMO assembly. The structures enabled comprehensive exploration of their structure-function relationships using glycan microarrays, revealing broad yet distinct recognition by Siglecs of the atypical Neu5Acα2-6GlcNAc motif. The work provides tools and new insight for the functional study and potential applications of Siglecs and HMOs.

Regiospecific 7-O-prenylation of anthocyanins by a fungal prenyltransferase.

Anthocyanins are a type of well-known natural flavonoids for their various beneficial health effects. However, prenylated anthocyanins are not discovered in nature although prenylation is believed to generally enhance the biological accessibility of flavonoids. In this article, we demonstrate the first example for prenylation of anthocyanins. A chemo-enzymatic approach was achieved for the synthesis of a series of 7-O-prenylated anthocyanins, using the fungal prenyltransferase CdpC3PT from Neosartorya fischeri.

Genome-wide identification of lncRNAs and mRNAs differentially expressed in human vascular smooth muscle cells stimulated by high phosphorus.

Background: Cardiovascular events are the primary cause of death for chronic kidney disease patients, which occurred via vascular calcification evolving pathogenically. Although a high level of phosphorus contributes to the induction of osteogenic differentiation of vascular smooth muscle cells (VSMCs), the role of lncRNA in this process awaits further study.Methods: In this study, we systematically investigated the variation of gene expression in human VSMCs induced by high phosphorus. LncRNAs and mRNAs expression were revealed by microarray analyses of the control group and high-phosphorus (HP) group. LncRNA-mRNA co-expression network was established based on the specific lncRNA-mRNA relationships. Hierarchical clustering was used to identify a common set of regulated genes. In addition, Gene Ontology enrichment, Kyoto Gene-Encyclopedia and genomic analyses were conducted for the mRNAs differentially expressed under high phosphorus.Result: RT-qPCR results confirmed that the expression of RUNX2, BMP2 and osteocalcin in HP group exhibited significant increases than in control group (p < .05). VSMC in HP group also showed higher intracellular calcium content. Volcano plots results show that 379 mRNAs and 728 lncRNAs different expressed in HP group. LncRNA-mRNA co-expression networks analysis revealed that 8 lncRNAs were the most highly connected lncRNAs. Quantitative analysis indicated that two lncRNAs were confirmed to increase significantly in the HP group. The mRNA expression of NT5E and ICAM1 were higher in group HP, while MAP3K7CL was lower than CON group (p < .05).Conclusion: This study provided a working list of lncRNAs that may be relevant to osteogenic differentiation, which presents a new insights into the mechanism of vascular calcification induced by high phosphorus in VSMCs.

Bone marrow mesenchymal stem cell-derived exosomes alleviate high phosphorus-induced vascular smooth muscle cells calcification by modifying microRNA profiles.

Vascular calcification is a common complication in patients with chronic kidney disease (CKD). It is an important predictor of cardiovascular disease and all-cause mortality. Previous studies have confirmed that bone marrow mesenchymal stem cell (BMSC) therapy can reduce vascular calcification, but the specific mechanism is still controversial. In this study, we aimed to investigate the mechanisms of BMSC-derived exosomes (EXO) in improving vascular calcification. BMSCs were cultured and EXO were isolated using the Total Exosome Isolation Reagent. Human aortic vascular smooth muscle cells (HA-VSMCs) were cultured into three groups: control group, high phosphorus group, and high phosphorus plus EXO group. Then, indicators related to smooth muscle cell calcification and microRNA profiles were analyzed. BMSC-derived exosomes inhibited high phosphorus-induced calcification in HA-VSMCs. Besides, EXO treatment reduced calcium content and decreased the alkaline phosphatase (AKP) activity in high phosphorus co-incubated HA-VSMCs. MicroRNA (miRNA) and mRNA expression profiles analyses revealed that 63 miRNAs were significantly upregulated and 1424 genes were significantly downregulated in HA-VSMCs after EXO treatment. Functional miRNA-gene regulatory network revealed that mTOR, MAPK, and Wnt signaling pathway were involved in vascular calcification. BMSC-derived exosomes alleviated high phosphorus-induced calcification in HA-VSMC through modifying miRNA profiles.

Selective geranylation of biflavonoids by Aspergillus terreus aromatic prenyltransferase (AtaPT).

Prenylation increases the bioactivity of flavonoids. Herein, we report the first examples of regioselective enzymatic geranylation of biflavonoids using Aspergillus terreus aromatic prenyltransferase (AtaPT). For biflavonoids 1-3 dimerized through a diphenyl linkage, geranylation occurs at the hydrogen bond involving C5''-OH group, which is less chemically accessible than other OH groups in the molecule. This study would be referential for developing green synthetic solutions for prenylated biflavonoids.

New Immunomodulating Polyhydroxypregnane Glycosides from the Roots of Cynanchum otophyllum C.K.Schneid.

Seven new polyhydroxypregnane glycosides, named cynotophyllosides P-V, together with three known analogs were isolated from the roots of Cynanchum otophyllum C.K.Schneid. Their structures were elucidated by a variety of spectroscopic techniques, as well as acid-catalyzed hydrolysis. All isolates were tested for their immunological activities in vitro against Con A- and LPS-induced proliferation of mice splenocytes. Immunoenhancing (for 1, 9) and immunosuppressive (for 2) activities were observed. Furthermore, cynotophylloside R (3) showed immunomodulatory as it enhanced the proliferation of splenocytes in low concentration and suppressed immune cells in concentration more than 1.0 µg/ml.

Discovery of NO Donor-Aurovertin Hybrids as Dual Ferroptosis and Apoptosis Inducers for Treating Triple Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is a highly lethal malignancy, and its clinical management encounters severe challenges due to its high metastatic propensity and the absence of effective therapeutic targets. To improve druggability of aurovertin B (AVB), a natural polyketide with a significant antiproliferative effect on TNBC, a series of NO donor/AVB hybrids were synthesized and tested for bioactivities. Among them, compound 4d significantly inhibited the proliferation and metastasis of TNBC in vitro and in vivo with better safety than that of AVB. The structure-activity relationship analysis suggested that the types of NO donor and the linkers had considerable effects on the activities. Mechanistic investigations unveiled that 4d induced apoptosis and ferroptosis by the reduction of mitochondrial membrane potential and the down-regulation of GPX4, respectively. The antimetastatic effect of 4d was associated with the upregulation of DUSP1. Overall, these compelling results underscore the tremendous potential of 4d for treating TNBC.

Convergent chemoenzymatic synthesis of O-GalNAc rare cores 5, 7, 8 and their sialylated forms.

All O-GalNAc glycans are derived from 8 cores with 2 or 3 monosaccharides linked via α- or ß-glycosidic bonds. While chemical and chemoenzymatic syntheses of ß-linked cores 1-4 and 6 and derived glycans have been well developed, the preparation of α-linked rare cores 5, 7, and 8 is challenging due to the presence of this 1,2-cis linkage. Meanwhile, the biosynthesis and functional roles of these structures are poorly understood. Herein, we synthesize 3 α-linked rare cores with exclusive α-configuration from a versatile precursor through multifaceted chemical modulations. Efficient regioselective α2-6sialylion of the rare cores was then achieved by Photobacterium damselae α2-6sialyltransferase-catalyzed reactions. These structures, together with ß-linked cores 1-4 and 6, and their sialylated forms, were fabricated into a comprehensive O-GalNAc core microarray to profile the binding of clinically important GalNAc-specific lectins. It is found that only Tn, (sialyl-)core 5, and core 7 are the binders of WFL, VVL, and SBA, while DBA only recognized (sialyl-)core 5, and Jacalin is the only lectin that binds core 8. In addition, activity assays of human α-N-acetylgalactosaminide α2-6sialyltransferases (ST6GalNAcTs) towards the cores suggested that ST6GalNAc1 may be involved in the biosynthesis of previously identified sialyl-core 5 and sialyl-core 8 glycans. In conclusion, we provide efficient routes to access α-linked O-GalNAc rare cores and derived structures, which are valuable tools for functional glycomics studies of mucin O-glycans.

Bone marrow mesenchymal stem cell-derived exosomal microRNA-381-3p alleviates vascular calcification in chronic kidney disease by targeting NFAT5.

Vascular calcification (VC) is a significant complication of chronic kidney disease (CKD) and cellular apoptosis is one of the intricate mechanisms of VC. Bone marrow mesenchymal stem cell-derived exosome (BMSC-Exo) alleviates VC, but the mechanism remains unclear. We investigated the mechanism of BMSC-Exo using high phosphate stimulated Human aortic smooth muscle cells (HA-VSMCs) and 5/6 subtotal nephrectomy (SNx) rat models. We demonstrated that the effect of BMSC-Exo on the inhibition of cellular apoptosis and calcification partially depended on exosomal microRNA-381-3p (miR-381-3p) both in vivo and in vitro, and confirmed that miR-381-3p could inhibit Nuclear Factor of Activated T cells 5 (NFAT5) expression by directly binding to its 3' untranslated region. Additionally, we found that severe calcification of arteries in dialysis patients was associated with decreased miR-381-3p and increased NFAT5 expression levels. Collectively, our findings proved that BMSC-Exo plays anti-calcification and anti-apoptosis roles in CKD by delivering enclosed miR-381-3p, which directly targets NFAT5 mRNA, and leads to a better understanding of the mechanism of CKD-VC.

Bone mesenchymal stem cell derived exosomes alleviate high phosphorus-induced calcification of vascular smooth muscle cells through the NONHSAT 084969.2/NF-κB axis.

Our previous study showed that bone marrow mesenchymal stem cell derived exosomes (BMSC-Exos) suppress high phosphorus (Pi)-induced calcification of vascular smooth muscle cells (VSMCs). However, the mechanism had remained unclear. This study aimed to investigate the mechanism by which BMSC-Exos inhibit vascular calcification (VC). We found that BMSC-Exos reduced high Pi-induced Runx2, osteocalcin and BMP2 expression and inhibited the calcium deposition. Gene expression of human VSMCs stimulated by Pi or Pi plus BMSC-Exos (Pi + Exo) was systematically examined by microarray technology. NONHSAT 084969.2 and transcription factor p65 expression was significantly lower in the Pi + Exo group compared with the Pi group. This finding indicated that NONHSAT 084969.2 and the nuclear factor-κB pathway might play an important role in VC inhibition by BMSC-Exos. By silencing NONHSAT 084969.2 with small interfering RNA, Runx2, BMP2, and osteocalcin expression was decreased significantly. The calcified nodule content and alkaline phosphatase activity were reduced after NONHSAT 084969.2 inhibition and p65, p50, and IκB kinase-α expression was decreased significantly. These results indicated that BMSC-Exos inhibited Pi-induced transdifferentiation and calcification of VSMCs by regulating the NONHSAT 084969.2/nuclear factor-κB axis.

Retinal Vessel Diameter and Chronic Kidney Disease in Rural China: A Cross-Sectional Study.

Few studies have examined the relationship between retinal microvascular abnormalities and chronic kidney disease (CKD). This study aims to examine the association between retinal vessel diameters and CKD in the rural China in order to provide the scientific basis for the early detection and diagnosis for CKD.Participants and data were extracted from the Handan Eye Study, a population-based cross-sectional study performed from 2006 to 2007. The central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were summarized by the average arteriolar and venular caliber of each eye. The estimated glomerular filtration rate (eGFR) and a urinary albumin to creatinine ratio (ACR) were recorded. Multivariate logistic regression models were used to determine any associations between CRAE, CRVE, arteriole-to-venule ratio (AVR), retinopathy, and CKD in the recruited participants.CKD was found in was 17.3% (892/5158) of this population with a 0.9% (48/5545) rate of reduced renal function and 16.7% (922/5538) rate of albuminuria. Retinopathy was present in 9.6% (571/5925) of participants. Compared to the 4th quartile of AVR, the first group was found to have a higher risk of albuminuria (odds ratio [OR] = 1.261, 95% confidence interval [95%CI]: 1.015-1.567, P = 0.037) and CKD (OR = 1.240, 95%CI: 1.000-1.537, P = 0.049) after adjustment for potential confounding variables. Retinopathy was associated with the occurrence of albuminuria (OR = 1.340, 95%CI: 1.067-1.685, P = 0.012) and CKD (OR = 1.341, 95%CI: 1.071-1.681, P = 0.010). In participants with diabetes, the ORs for the 1st and 4th quartiles of CRAE and CRVE were 2.292 (95%CI: 1.076-4.881, P = 0.032) and 2.113 (95%CI: 1.006-4.438, P = 0.048), respectively. Among the participants with hypertension, retinopathy was also observed to be associated with CKD (OR = 1.306, 95%CI: 1.003-1.699, P = 0.047).The parameters of retinal vessel diameter may be a useful index evaluating the occurrence and development of CKD.

Prevention of propofol-induced pain in children: pretreatment with small doses of ketamine.

STUDY OBJECTIVE: To evaluate the efficacy of ketamine in preventing propofol injection pain in children. DESIGN: Prospective, randomized, double-blinded, placebo-controlled study. SETTING: University-affiliated hospital. PATIENTS: 192 ASA physical status 1 and 2 pediatric patients. INTERVENTIONS: Patients were randomly assigned to 4 groups. Group S (control) received normal saline as a placebo; Group K1, Group K3, and Group K5 received 0.1 mg/kg, 0.3 mg/kg, and 0.5 mg/kg of ketamine, respectively. Fifteen seconds after the ketamine injection, patients were injected with propofol at a rate of 12 mL/min until loss-of-eyelash reflex. MEASUREMENT: Pain was evaluated blindly at the time of induction using a 4-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain. Adverse effects were recorded. Characteristics of induction of anesthesia, such as dose of propofol and time from propofol injection to loss of consciousness (induction duration), were noted. MAIN RESULTS: 39 (84.8%) Group S (control) patients had pain. Pretreatment with ketamine reduced the frequency of pain significantly to 56.5%, 17.0%, and 14.9% in Groups K1, K3, and K5, respectively. Furthermore, the frequency of moderate and severe pain in Group K1 (21.8%), Group K3 (6.4%), and Group K5 (4.3%) was significantly (P < 0.001, respectively) reduced compared with Group S (76.1%). Moreover, the dose of propofol for induction in Group K5 was smaller than in Group S, Group K1, and Group K3 (P < 0.05). One patient in Group K5 had emergence agitation. CONCLUSION: Pretreatment with a small dose of ketamine (0.3 mg/kg) reduced the frequency and intensity of propofol injection pain without severe adverse effects.