A chemo-selective enrichment strategy to achieve in-depth coverage of methyllysine proteome.

Proteomics is a powerful method to comprehensively understand cellular posttranslational modifications (PTMs). Due to low abundance, tryptic peptides with PTMs are usually enriched for enhanced coverage by LC-MS/MS. Affinity chromatography for phosphoproteomes by metal-oxide and pan-specific antibodies for lysine acetylome allow identification of tens of thousands of modification sites. Lysine methylation is a significant PTM, however, only hundreds of methylation sites were identified from available approaches. Here we report an aryl diazonium-based chemoselective strategy that enables enrichment of monomethyllysine (Kme1) peptides via covalent bond with extraordinary sensitivity. We identified more than ten thousand Kme1 peptides from diverse cell lines and mouse tissues, that implied wide lysine methylation impact on cellular processes. In addition, we found a significant amount of methyl marks that were not S-adenosyl methionine (SAM)-dependent by isotope labeling experiments. And therefore, this method paves a way to broad application in lysine methylation research and new biology discovery.

The protective effect of vitexin on hypertensive nephropathy rats.

INTRODUCTION: Vitexin is a natural flavonoid compound extracted from Vitex leaves or seeds, exhibiting various pharmacological activities including anticancer, antihypertensive, anti-inflammatory, and spasmolytic effects. However, its protective effects on hypertensive nephropathy (HN) and the underlying mechanisms remain unclear. METHODS: Spontaneous hypertension rats were fed a high-sugar and high-fat diet for 8 weeks to induce the disease HN model. From the 5th week, the rats were administered vitexin via gavage. Blood pressure was measured bi-weekly using the tail-cuff method. Histopathological changes were assessed using HE staining, and biochemical analyses were performed to evaluate the effects of vitexin on HN rats. The underlying mechanisms of vitexin treatment were investigated through western blotting. RESULTS: The data demonstrated that vitexin significantly lowered systolic, diastolic, and mean arterial pressures, and ameliorated histopathological changes in HN rats. Biochemical analyses revealed that vitexin reduced the levels of creatinine (Cr), blood urea nitrogen (BUN), total cholesterol (TC), triglycerides (TG), total protein (TP), low-density lipoprotein cholesterol (LDL-C), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), malondialdehyde (MDA), and advanced glycation end products (AGEs), while increasing the levels of albumin (ALB) and superoxide dismutase (SOD). Western blotting results indicated that vitexin treatment decreased the expression of TNF-α, IL-6, and nuclear factor kappa-B (NF-κB), while increasing the expression of SOD. CONCLUSION: The findings of this study suggest that vitexin exerts protective effects against HN, providing pharmacological evidence for its potential use in HN treatment.