MicroRNA-146a-5p-modified human umbilical cord mesenchymal stem cells enhance protection against diabetic nephropathy in rats through facilitating M2 macrophage polarization.

BACKGROUND: Diabetic nephropathy (DN) is a severe complication of diabetes mellitus and a common cause of end-stage renal disease (ESRD). Mesenchymal stem cells (MSCs) possess potent anti-inflammatory and immunomodulatory properties, which render them an attractive therapeutic tool for tissue damage and inflammation. METHODS: This study was designed to determine the protective effects and underlying mechanisms of human umbilical cord-derived MSCs (UC-MSCs) on streptozotocin-induced DN. Renal function and histological staining were used to evaluate kidney damage. RNA high-throughput sequencing on rat kidney and UCMSC-derived exosomes was used to identify the critical miRNAs. Co-cultivation of macrophage cell lines and UC-MSCs-derived conditional medium were used to assess the involvement of macrophage polarization signaling. RESULTS: UC-MSC administration significantly improved renal function, reduced the local and systemic inflammatory cytokine levels, and attenuated inflammatory cell infiltration into the kidney tissue in DN rats. Moreover, UC-MSCs shifted macrophage polarization from a pro-inflammatory M1 to an anti-inflammatory M2 phenotype. Mechanistically, miR-146a-5p was significantly downregulated and negatively correlated with renal injury in DN rats as determined through high-throughput RNA sequencing. Importantly, UC-MSCs-derived miR-146a-5p promoted M2 macrophage polarization by inhibiting tumor necrosis factor receptor-associated factor-6 (TRAF6)/signal transducer and activator of transcription (STAT1) signaling pathway. Furthermore, miR-146a-5p modification in UC-MSCs enhanced the efficacy of anti-inflammation and renal function improvement. CONCLUSIONS: Collectively, our findings demonstrate that UC-MSCs-derived miR-146a-5p have the potential to restore renal function in DN rats through facilitating M2 macrophage polarization by targeting TRAF6. This would pave the way for the use of miRNA-modified cell therapy for kidney diseases.

Genome-Wide Identification and Characterization of SPX Domain-Containing Members and Their Responses to Phosphate Deficiency in Brassica napus.

The importance of SPX domain-encoding proteins to phosphate (Pi) homeostasis and signaling pathways has been well-documented in rice and Arabidopsis. However, global information and responses of SPX members to P stress in allotetraploid Brassica napus, one of the world's major oil crops that is sensitive to P deficiency, remain undefined. We identified a total of 69 SPX domain-containing genes in the B. napus genome. Based on the domain organizations, these genes were classified into four distinct subfamilies-SPX (11), SPX-EXS (43), SPX-MFS (8), and SPX-RING (7)-that represented clear orthologous relationships to their family members in Arabidopsis. A cis-element analysis indicated that 2 ∼ 4 P1BS elements were enriched in the promoter of SPX subfamily genes except BnaSPX4s. RNA-Seq analysis showed that BnaSPX genes were differentially expressed in response to Pi deficiency. Furthermore, quantitative real-time reverse transcription PCR revealed that nine SPX subfamily genes were significantly induced by Pi starvation and recovered rapidly after Pi refeeding. A functional analysis of two paralogous BnaSPX1 genes in transgenic Arabidopsis indicated their functional divergence during long-term evolution. This comprehensive study on the abundance, molecular characterization and responses to Pi deficiency of BnaSPX genes provides insights into the structural and functional diversities of these family members in B. napus and provides a solid foundation for future functional studies of BnaSPX genes. Highlight: The genome-wide identification and characterization of SPX genes in B. napus and their responses to Pi deficiency provide comprehensive insights into the structural and functional diversities of the family members in B. napus and their potential in Pi homeostasis and signaling responsiveness to Pi stress.