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Simple Summary: tRF-27 has been identified as upregulated in both naïve trastuzumab-resistant HER2-positive breast cancer cells and patient samples, positioning it as a potential biomarker. However, the underlying mechanisms of this upregulation remain unclear. This study proposes that the abnormal transcription of specific tRNA-Cys-GCA isodecoders in naïve trastuzumab-resistant cells might contribute to the accumulation of tRF-27. Additionally, the reduction in H3K27me3 modifications at these tRNA genes, attributed to imbalances in histone modification enzymes, appears to influence tRNA transcription alterations. Building upon these findings, our research demonstrates that the application of a demethylase inhibitor may offer a potential strategy to overcome trastuzumab resistance. tRNA-derived fragments (tRFs) play crucial roles in cancer progression. Among them, tRF-27 has been identified as a key factor in promoting naïve trastuzumab resistance in HER2-positive breast cancer. However, the origin of tRF-27 remains uncertain. In this study, we propose that the upregulated expression of specific cysteine tRNAs may lead to the increased accumulation of tRF-27 in trastuzumab-resistant JIMT1 cells. Mechanistically, the reduced inhibitory H3K27me3 modification at the promoter regions of tRF-27-related tRNA genes in JIMT1 cells, potentially resulting from decreased EZH2 and increased KDM6A activity, may be a critical factor stimulating the transcriptional activity of these tRNA genes. Our research offers fresh insights into the mechanisms underlying elevated tRF-27 levels in trastuzumab-resistant breast cancer cells and suggests potential strategies to mitigate trastuzumab resistance in clinical treatments. [ABSTRACT FROM AUTHOR]

Cardamine violifolia, a species belonging to the Brassicaceae family, is a novel vegetable crop that is rich in glucosinolates. However, the specific glucosinolate profiles in this species remain unknown. In the present study, four parts of C. violifolia were collected including central leaves (CLs), outer leaves (OLs), petiole (P), and root (R). The highest level of total glucosinolate was observed in the R. A total of 19 glucosinolates were found in C. violifolia. The predominant glucosinolate compounds were 3-methylbutyl glucosinolate, 6-methylsulfinylhexyl glucosinolate, Indol-3-ylmethyl glucosinolate, 4-methoxyglucobrassicin, and neoglucobrassicin. A transcriptome analysis showed that 16 genes, including BCAT1, BCAT3-6, CYP79A2, CYP79B2-3, CYP83A1, CYP83B1, and SOT17-18, and nine metabolites, such as valine, tryptophan, and 1-methylpropyl glucosinolate, were enriched in the glucosinolate biosynthesis pathway. These genes may be involved in the regulation of glucosinolate accumulation among the four parts. A weighted gene co-expression analysis showed that five genes were predicted to regulate glucosinolate accumulation, including ABC transporter G family member 19, 3-ketoacyl-CoA synthase 19, and pyruvate decarboxylase 1. This study deepens our understanding of the nutrient quality of C. violifolia and provides insights into the regulatory mechanism of glucosinolate accumulation in C. violifolia. [ABSTRACT FROM AUTHOR]

Perennial trees develop and coordinate endogenous response signaling pathways, including their crosstalk and convergence, to cope with various environmental stresses which occur simultaneously in most cases. These processes are involved in gene transcriptional regulations that depend on dynamic interactions between regulatory proteins and corresponding chromatin regions, but the mechanisms remain poorly understood in trees. In this study, we detected chromatin regulatory landscapes of poplar under abscisic acid, methyl jasmonate, salicylic acid and sodium chloride (NaCl) treatment, through integrating ATAC-seq and RNA-seq data. Our results showed that the degree of chromatin accessibility for a given gene is closely related to its expression level. However, unlike the gene expression that shows treatment-specific response patterns, changes in chromatin accessibility exhibit high similarities under these treatments. We further proposed and experimentally validated that a homologous gene copy of RESPONSIVE TO DESICCATION 26 mediates the crosstalk between jasmonic acid and NaCl signaling pathways by directly regulating the stress-responsive genes and that circadian clock-related transcription factors like REVEILLE8 play a central role in response of poplar to these treatments. Overall, our study provides a chromatin insight into the molecular mechanism of transcription regulatory networks in response to different environmental stresses and raises the key roles of the circadian clock of poplar to adapt to adverse environments. [ABSTRACT FROM AUTHOR]