Swimming exercise activates peroxisome proliferator-activated receptor-alpha and mitigates age-related renal fibrosis in rats.

Aging results in progressive decline of renal function as well as histological alterations including glomerulosclerosis and interstitial fibrosis. The objective of current study was to test the benefits of moderate swimming exercise in aged rats on renal function and structure and investigate its molecular mechanisms. Aged rats of 21-months old were given moderate swimming exercise for 12 weeks. Swimming exercise in aged rats led to reduced plasma levels of creatinine and blood urea nitrogen. Periodic acid-Schiff staining results revealed reduced renal injury scores in aged rats after swimming exercise. Swimming exercise in aged rats mitigated renal fibrosis and downregulated the mRNA expression of Acta2, Fn, Col1a, Col4a, and Tgfb1 in kidneys. Swimming exercise in aged rats attenuated lipid accumulation and reduced levels of triglyceride in kidneys. Swimming exercise in aged rats abated oxidative stress, evidenced by reduced MDA levels and increased MnSOD activities in kidneys. Swimming exercise in aged rats inhibited NF-κB activities and reduced renal expression of pro-inflammatory cytokines including MCP-1, IL-1ß and IL-6. Mechanistically, swimming exercise restored mRNA and protein expression of PPAR-α in kidney of aged rats. Furthermore, swimming exercise in aged rats increased expression of PPAR-α-targeting microRNAs including miR-21 and miR-34a. Collectively, swimming exercise activated PPAR-α, which partly explained the benefits of moderate swimming exercise in aging kidneys.

Transcriptome-Wide Characterization of piRNAs during the Developmental Process of European Honey-Bee Larval Guts.

piRNAs play pivotal roles in maintaining genome stability, regulating gene expression, and modulating development and immunity. However, there are few piRNA-associated studies on honey-bees, and the regulatory role of piRNAs in the development of bee guts is largely unknown. Here, the differential expression pattern of piRNAs during the developmental process of the European honey-bee (Apis mellifera) larval guts was analyzed, followed by investigation of the regulatory network and the potential function of differentially expressed piRNAs (DEpiRNAs) in regulating gut development. A total of 843 piRNAs were identified in the larval guts of A. mellifera; among these, 764 piRNAs were shared by 4- (Am4 group), 5- (Am5 group), and 6-day-old (Am6 group) larval guts, while 11, 67, and one, respectively, were unique. The first base of piRNAs in each group had a cytosine (C) bias. Additionally, 61 up-regulated and 17 down-regulated piRNAs were identified in the "Am4 vs. Am5" comparison group, further targeting 9, 983 genes, which were involved in 50 GO terms and 142 pathways, while two up-regulated and five down-regulated piRNAs were detected in the "Am5 vs. Am6" comparison group, further targeting 1, 936 genes, which were engaged in 41 functional terms and 101 pathways. piR-ame-742536 and piR-ame-856650 in the "Am4 vs. Am5" comparison group as well as piR-ame-592661 and piR-ame-31653 in the "Am5 vs. Am6" comparison group were found to link to the highest number of targets. Further analysis indicated that targets of DEpiRNAs in these two comparison groups putatively regulate seven development-associated signaling pathways, seven immune-associated pathways, and three energy metabolism pathways. Moreover, the expression trends of five randomly selected DEpiRNAs were verified based on stem-loop RT-PCR and RT-qPCR. These results were suggestive of the overall alteration of piRNAs during the larval developmental process and demonstrated that DEpiRNAs potentially modulate development-, immune-, and energy metabolism-associated pathways by regulating the expression of corresponding genes via target binding, further affecting the development of A. mellifera larval guts. Our data offer a novel insight into the development of bee larval guts and lay a basis for clarifying the underlying mechanisms.