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Efficient intracellular delivery of protein drugs is critical for protein therapy. The combination of protein drugs with chemotherapeutics represents a promising strategy in enhancing anti-cancer effect. However, co-delivery systems for efficient delivery of these two kinds of drugs are still lacking because of their different properties. Herein, we show a well-designed delivery system based on dynamic covalent bond for efficient intracellular co-delivery of ribonuclease A (RNase A) and doxorubicin (DOX). Two polymers, PEG-b-P(Asp-co-AspDA) and PAE-b-P(Asp-co-AspPBA), and two 2-acetylphenylboronic acid (2-APBA)-functionalized drugs, 2-APBA-RNase A and 2-APBA-DOX, self-assemble into mixed-shell nanoparticles (RNase A/DOX@MNPs) via dynamic phenylboronic acid (PBA)-catechol bond between PBA and dopamine (DA) moieties. The PBA-catechol bond endows the nanoparticles with high stability and excellent stimulus-responsive drug release behavior. Under the slight acidic environment at tumor tissue, RNase A/DOX@MNPs are positively charged, promoting their endocytosis. Upon cellular uptake into endosome, further protonation of PAE chains leads to the rupture of endosomes because of the proton sponge effect and the cleavage of PBA-catechol bond promotes the release of two drugs. In cytoplasm, the high level of GSH removed the modification of 2-APBA on drugs. The restored RNase A and DOX show a synergistic and enhanced antic-cancer effect. This system may be a promising platform for intracellular co-delivery of protein drugs and chemotherapeutics. [ABSTRACT FROM AUTHOR]

WOX11/12 is a homeobox gene of WOX11 and WOX12 in Arabidopsis that plays important roles in crown root development and growth. It has been reported that WOX11/12 participates in adventitious root (AR) formation and different abiotic stress responses, but the downstream regulatory network of WOX11/12 in poplar remains to be further investigated. In this study, we found that PagWOX11/12a is strongly induced by PEG-simulated drought stress. PagWOX11/12a -overexpressing poplar plantlets showed lower oxidative damage levels, greater antioxidant enzyme activities and reactive oxygen species (ROS) scavenging capacity than non-transgenic poplar plants, whereas PagWOX11/12a dominant repression weakened root biomass accumulation and drought tolerance in poplar. RNA-seq analysis revealed that several differentially expressed genes (DEGs) regulated by PagWOX11/12a are involved in redox metabolism and drought stress response. We used RT-qPCR and yeast one-hybrid (Y1H) assays to validate the downstream target genes of PagWOX11/12a. These results provide new insights into the biological function and molecular regulatory mechanism of WOX11/12 in the abiotic resistance processes of poplar. • PagWOX11/12a is induced by PEG-simulated drought stress. • Overexpression of PagWOX11/12a enhances drought tolerance by regulating ROS levels and antioxidant enzyme activity. • PagWOX11/12a can bind to the PagBURP24 and PagbHLH63 promoters and activate their expression. [ABSTRACT FROM AUTHOR]

NAC transcription factors play a significant role in regulating plant responses to biological processes and environmental stresses. Our previous study revealed 21 ThNAC proteins, and ThNAC13 is a nuclear protein that responds to saline stress in Tamarix hispida. To determine whether ThNAC13 regulates downstream genes, RNA sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) were used to identify the binding sites of ThNAC13 at the whole-genome level. In RNAi-silenced ThNAC13 transgenic Tamarix , a total of 4 downregulated differentially expressed genes (DEGs) and 114 peaks strongly associated with four different motifs were identified compared with those in empty vector transgenic Tamarix under salt stress. The c48149.graph_c0 gene contains the key domain of the phloem protein 2 (PP2) protein and is a candidate gene downstream of ThNAC13. Yeast one-hybrid (Y1H), chromatin immunoprecipitation (ChIP) and dual-luciferase reporter (LUC) assays were used to identify ThNAC13 as an upstream regulator of ThPP2. Transgenic Tamarix plants in which ThPP2 was transiently expressed or silenced via RNAi were used for functional gain and loss experiments. The ThPP2- overexpressing plants exhibited decreased hydrogen peroxide (H 2 O 2), superoxide (O 2 •−), and electrolyte leakage (EL) and malondialdehyde (MDA) levels and increased superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity. In contrast, transient RNAi-mediated silencing of ThPP2 in Tamarix had the opposite effect. ThNAC13 binds to the promoter region of the ThPP2 gene and reduces the reactive oxygen species (ROS) accumulation and enhances antioxidant enzyme activity, positively regulating salt stress tolerance in Tamarix. • 4 down-regulated DEGs and 4 different motifs were identified in RNAi-silenced ThNAC13 compare with empty vector transgenic Tamarix under salt stress. • The phloem protein 2 (PP2) protein as a downstream gene by ThNAC13 TFs. • Overexpression of ThPP2 Tamarix decreased the contents of H 2 O 2 , O 2 •−, EL and MDA; induced the activities of SOD, POD and CAT. • In contrast, transiently RNAi-silenced ThPP2 Tamarix showed the opposite result. • ThNAC13 binds to ThPP2 gene through reduces the ROS accumulation and enhances antioxidant enzyme activity to improve salt stress tolerance. [ABSTRACT FROM AUTHOR]