Rationale: Over 50% of heart failure patients have preserved, rather than reduced ejection fraction (HFpEF vs. HFrEF). Complexity of its pathophysiology and the lack of animal models hamper the development of effective therapy for HFpEF. Objective: This study was designed to investigate the metabolic mechanisms of HFpEF and test therapeutic interventions using a novel animal model.Methods and Results: By combining the age, long-term high-fat diet and desoxycorticosterone pivalate challenge in a mouse model we were able to recapture the myriad features of HFpEF. In these mice, mitochondrial hyperacetylation exacerbated while increasing ketone body availability rescued the phenotypes. The HFpEF mice exhibited overproduction of interleukin (IL)-1β/IL-18, and tissue fibrosis due to increased assembly of NLPR3 inflammasome on hyperacetylated mitochondria. Increasing β-hydroxybutyrate (β-OHB) level attenuated NLPR3 inflammasome formation and antagonized proinflammatory cytokines-triggered mitochondrial dysfunction and fibrosis. Moreover, β-OHB downregulated the acetyl-CoA pool and mitochondrial acetylation, partially via activation of citrate synthase and inhibition of fatty acid uptake. Conclusions: Therefore, we identify the interplay of mitochondrial hyperacetylation and inflammation as a key driver in HFpEF pathogenesis which can be ameliorated by promoting β-OHB abundance.

The glycoprotein spike (S) on the surface of SARS-CoV-2 is a determinant for viral invasion and host immune response. Herein, we characterized the site-specific N-glycosylation of S protein at the level of intact glycopeptides. All 22 potential N-glycosites were identified in the S-protein protomer and were found to be preserved among the 753 SARS-CoV-2 genome sequences. The glycosites exhibited glycoform heterogeneity as expected for a human cell-expressed protein subunit. We identified masses that correspond to 157 N-glycans, primarily of the complex type. In contrast, the insect cell-expressed S protein contained 38 N-glycans, completely of the high-mannose type. Our results revealed that the glycan types were highly determined by the differential processing of N-glycans among human and insect cells, regardless of the glycosites’ location. Moreover, the N-glycan compositions were conserved among different sizes of subunits. Our study indicate that the S protein N-glycosylation occurs regularly at each site, albeit the occupied N-glycans were diverse and heterogenous. This N-glycosylation landscape and the differential N-glycan patterns among distinct host cells are expected to shed light on the infection mechanism and present a positive view for the development of vaccines and targeted drugs.

Mitochondrial dysfunction is a key feature of injury to numerous tissues and stem cell aging. Although the tissue regenerative role of mesenchymal stem cell (MSC)derived extracellular vesicles (MSC-EVs) is well known, their specific role in regulating mitochondrial function in target cells remains elusive. Here, we report that MSC-EVs attenuated mtDNA damage and inflammation after acute kidney injury (AKI) and that this effect was at least partially dependent on the mitochondrial transcription factor A (TFAM) pathway. In detail, TFAM and mtDNA were depleted by oxidative stress in MSCs from aged or diabetic donors. Higher levels of TFAM mRNA and mtDNA were detected in normal control (NC) MSC-EVs than in TFAM-knockdown (TFAM-KD) and aged EVs. EV-mediated TFAM mRNA transfer in recipient cells was unaffected by transcriptional inhibition. Accordingly, the application of MSC-EVs restored TFAM protein and TFAM-mtDNA complex (nucleoid) stability, thereby reversing mtDNA deletion and mitochondrial oxidative phosphorylation (OXPHOS) defects in injured renal tubular cells. Loss of TFAM also led to downregulation of multiple anti-inflammatory miRNAs and proteins in MSC-EVs. In vivo, intravenously injected EVs primarily accumulated in the liver, kidney, spleen, and lung. MSC-EVs attenuated renal lesion formation, mitochondrial damage, and inflammation in mice with AKI, whereas EVs from TFAM-KD or aged MSCs resulted in poor therapeutic outcomes. Moreover, TFAM overexpression (TFAM-OE) improved the rescue effect of MSC-EVs on mitochondrial damage and inflammation to some extent. This study suggests that MSC-EVs are promising nanotherapeutics for diseases characterized by mitochondrial damage, and TFAM signaling is essential for maintaining their regenerative capacity.

SummaryThe glycoprotein spike (S) on the surface of SARS-CoV-2 is a determinant for viral invasion and host immune response. Herein, we characterized the site-specific N-glycosylation of S protein at the level of intact glycopeptides. All 22 potential N-glycosites were identified in the S-protein protomer and were found to be preserved among the 753 SARS-CoV-2 genome sequences. The glycosites exhibited glycoform heterogeneity as expected for a human cell-expressed protein subunits. We identified masses that correspond to 157 N-glycans, primarily of the complex type. In contrast, the insect cell-expressed S protein contained 38 N-glycans, primarily of the high-mannose type. Our results revealed that the glycan types were highly determined by the differential processing of N-glycans among human and insect cells. This N-glycosylation landscape and the differential N-glycan patterns among distinct host cells are expected to shed light on the infection mechanism and present a positive view for the development of vaccines and targeted drugs.

No abstract

MicroRNAs (miRNAs) are frequently deregulated in human tumors, and play important roles in tumor development and progression. The pathological roles of miRNAs in neurofibromatosis type 1 (NF1) tumorigenesis are largely unknown. We demonstrated that miR-10b was up-regulated in primary Schwann cells isolated from NF1 neurofibromas and in cell lines and tumor tissues from malignant peripheral nerve sheath tumors (MPNSTs). Intriguingly, a significantly high level of miR-10b correlated with low neurofibromin expression was found in a neuroectodermal cell line: Ewing's sarcoma SK-ES-1 cells. Antisense inhibiting miR-10b in NF1 MPNST cells reduced cell proliferation, migration and invasion. Furthermore, we showed that NF1 mRNA was the target for miR-10b. Overexpression of miR-10b in 293T cells suppressed neurofibromin expression and activated RAS signaling. Antisense inhibition of miR-10b restored neurofibromin expression in SK-ES-1 cells, and decreased RAS signaling independent of neurofibromin in NF1 MPNST cells. These results suggest that miR-10b may play an important role in NF1 tumorigenesis through targeting neurofibromin and RAS signaling.

Small cell lung cancer (SCLC) is a rapidly progressing, incurable cancer that frequently spreads to bone. New insights are needed to identify therapeutic targets to prevent or retard SCLC metastatic progression. Human SCLC SBC-5 cells in mouse xenograft models home to skeletal and nonskeletal sites, whereas human SCLC SBC-3 cells only pervade nonskeletal sites. Because microRNAs (miRNA) often act as tumor regulators, we investigated their role in preclinical models of SCLC. miRNA expression profiling revealed selective and reduced expression of miRNA (miR)-335 and miR-29a in SBC-5 cells, compared with SBC-3 cells. In SBC-5 cells, miR-335 expression correlated with bone osteolytic lesions, whereas miR-29a expression did not. Overexpression of miR-335 in SBC-5 cells significantly reduced cell migration, invasion, proliferation, colony formation, and osteoclast induction in vitro. Importantly, in miR-335 overexpressing SBC-5 cell xenografts (n ¼ 10), there were minimal osteolytic lesions in the majority of mice and none in three mice. Expression of RANK ligand (RANKL) and insulin-like growth factor-I receptor (IGF-IR), key mediators of bone metastases, were elevated in SBC-5 as compared with SBC-3 cells. Mechanistically, overexpression of miR-335 in SBC-5 cells reduced RANKL and IGF-IR expression. In conclusion, loss of miR-335 promoted SCLC metastatic skeletal lesions via deregulation of IGF-IR and RANKL pathways and was associated with metastatic osteolytic skeletal lesions.

A Bacillus strain, denoted as PY-1, was isolated from the vascular bundle of cotton. Biochemical, physiological and 16S rDNA sequence analysis proved that it should belong to Bacillus subtilis. The PY-1 strain showed strong ability against many common plant fungal pathogens in vitro. The antibiotics produced by this strain were stable in neutral and basic conditions, and not sensitive to high temperature. From the culture broth of PY-1 strain, five antifungal compounds were isolated by acidic precipitation, methanol extraction, gel filtration and reverse-phase HPLC. Advanced identification was performed by mass spectrometry and nuclear magnetic resonance spectroscopy. These five antifungal compounds were proved to be the isomers of iturin A: A2, A3, A4, A6 and A7. In fast atom bombardment mass spectrometry/mass spectrometry collision-induced dissociation spectra, fragmentation ions from two prior linear acylium ions were observed, and the prior ion, Tyr-Asn-Gln-Pro-Asn-Ser-betaAA-Asn-CO+, was first reported.