Ethylene regulates climacteric fruit ripening, and EIN3-LIKE1 (EIL1) plays an important role in this process. In apple (), fruit coloration is accompanied by ethylene release during fruit ripening, but the molecular mechanism that underlies these two physiological processes is unknown. In this study, we found that ethylene treatment markedly induced fruit coloration as well as the expression of , a positive regulator of anthocyanin biosynthesis and fruit coloration. In addition, we found that MdEIL1 directly bound to the promoter of and transcriptionally activated its expression, which resulted in anthocyanin biosynthesis and fruit coloration. Furthermore, MdMYB1 interacted with the promoter of , a key regulator of ethylene biosynthesis, thereby providing a positive feedback for ethylene biosynthesis regulation. Overall, our findings provide insight into a mechanism involving the synergistic interaction of the ethylene signal with the MdMYB1 transcription factor to regulate ethylene biosynthesis and fruit coloration in apple.

BackgroundPlant growth is greatly affected by low temperatures, and the expression of a number of genes is induced by cold stress. Although many genes in the cold signaling pathway have been identified in Arabidopsis, little is known about the transcription factors involved in the cold stress response in apple.ResultsHere, we show that the apple bHLH (basic helix-loop-helix) gene MdCIbHLH1 (Cold-Induced bHLH1), which encodes an ICE-like protein, was noticeably induced in response to cold stress. The MdCIbHLH1 protein specifically bound to the MYC recognition sequences in the AtCBF3 promoter, and MdCIbHLH1 overexpression enhanced cold tolerance in transgenic Arabidopsis. In addition, the MdCIbHLH1 protein bound to the promoters of MdCBF2 and favorably contributed to cold tolerance in transgenic apple plants by upregulating the expression of MdCBF2 through the CBF (C-repeat-binding factor) pathway. Our findings indicate that MdCIbHLH1 functions in stress tolerance in different species. For example, ectopic MdCIbHLH1 expression conferred enhanced chilling tolerance in transgenic tobacco. Finally, we observed that cold induces the degradation of the MdCIbHLH1 protein in apple and that this degradation was potentially mediated by ubiquitination and sumoylation.ConclusionsBased on these findings, MdCIbHLH1 encodes a transcription factor that is important for the cold tolerance response in apple.

Circular RNAs (circRNAs), as a novel class of endogenously expressed non-coding RNAs (ncRNAs), have a high stability and often present tissue-specific expression and evolutionary conservation. Emerging evidence has suggested that circRNAs play an essential role in complex human pathologies. Notably, circRNAs, important gene modulators in the immune system, are strongly associated with the occurrence and development of autoimmune diseases. Here, we focus on the roles of circRNAs in immune cells and immune regulation, highlighting their potential as biomarkers and biological functions in autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), primary biliary cholangitis (PBC), and psoriasis, aiming at providing new insights into the diagnosis and therapy of these diseases. Facts • CircRNAs are related to various biological processes in immune cells, as well as immune regulation under multifarious physiological and pathological conditions. • CircRNAs serve as potential biomarkers for the diagnosis and severity of certain autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), primary biliary cholangitis (PBC). • CircRNAs contribute to the development of autoimmune diseases by acting as miRNA sponges to regulate many biological processes, including DNA methylation, immune response, and inflammatory response. • Certain circRNAs, such as cia-cGAS and dsRNA-containing circRNAs, may act as potential targets for the treatment of autoimmune diseases.

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Objective Our study aims to assay the irisin level and investigate the relationships of irisin level with body mass index (BMI), body composition and bone metabolism in the polycystic ovary syndrome (PCOS) and control women.Methods Fifty two PCOS and 39 control women were recruited. Serum sex hormone, fasting insulin and C-peptide were tested. Fasting serum irisin and adiponectin were measured with enzyme-linked immunosorbent assay. Body composition and bone mineral density were assayed by dual energy X-ray absorptiometry.Results Polycystic ovary syndrome women showed different body compositions compared with controls. Serum irisin level of PCOS did not show significant difference compared with controls although it was decreased. The level of adiponectin in PCOS patients was significantly reduced. BMI had no correlation with irisin level. It indicated a positive correlation between serum irisin levels and bone mineral density in the control group and a negative correlation in the PCOS group after BMI and age adjusted. Furthermore, total lean mass has a significant effect on irisin concentration in the PCOS group. There are no correlations between adiponection and body compositions and bone mineral density in both groups.Conclusions The abnormal body composition in PCOS may contribute to the circulation irisin. The crosstalk of irisin in different organs was found and may be related to disease development in PCOS.