Influences of Ipomoea batatas Anti-Cancer Peptide on Tomato Defense Genes.

AIMS: This study investigates the impact of IbACP (Ipomoea batatas anti-cancer peptide) on defense-related gene expression in tomato leaves, focusing on its role in plant defense mechanisms. BACKGROUND: Previously, IbACP was isolated from sweet potato leaves, and it was identified as a peptide capable of inducing an alkalinization response in tomato suspension culture media. Additionally, IbACP was found to regulate the proliferation of human pancreatic adenocarcinoma cells. OBJECTIVE: Elucidate IbACP's molecular influence on defense-related gene expression in tomato leaves using next-generation sequencing analysis. METHOD: To assess the impact of IbACP on defense-related gene expression, transcriptome data were analyzed, encompassing various functional categories such as photosynthesis, metabolic processes, and plant defense. Semi-quantitative reverse-transcription polymerase chain reaction analysis was employed to verify transcription levels of defense-related genes in tomato leaves treated with IbACP for durations ranging from 0 h (control) to 24 h. RESULTS: IbACP induced jasmonic acid-related genes (LoxD and AOS) at 2 h, with a significant up-regulation of salicylic acid-dependent gene NPR1 at 24 h. This suggested a temporal antagonistic effect between jasmonic acid and salicylic acid during the early hours of IbACP treatment. Downstream ethylene-responsive regulator genes (ACO1, ETR4, and ERF1) were consistently down-regulated by IbACP at all times. Additionally, IbACP significantly up-regulated the gene expressions of suberization-associated anionic peroxidases (TMP1 and TAP2) at all time points, indicating enhanced suberization of the plant cell wall to prevent pathogen invasion. CONCLUSION: IbACP enhances the synthesis of defense hormones and up-regulates downstream defense genes, improving the plant's resistance to biotic stresses.

Use of phase plate cryo-EM reveals conformation diversity of therapeutic IgG with 50 kDa Fab fragment resolved below 6 Å.

While cryogenic electron microscopy (cryo-EM) is fruitfully used for harvesting high-resolution structures of sizable macromolecules, its application to small or flexible proteins composed of small domains like immunoglobulin (IgG) remain challenging. Here, we applied single particle cryo-EM to Rituximab, a therapeutic IgG mediating anti-tumor toxicity, to explore its solution conformations. We found Rituximab molecules exhibited aggregates in cryo-EM specimens contrary to its solution behavior, and utilized a non-ionic detergent to successfully disperse them as isolated particles amenable to single particle analysis. As the detergent adversely reduced the protein-to-solvent contrast, we employed phase plate contrast to mitigate the impaired protein visibility. Assisted by phase plate imaging, we obtained a canonical three-arm IgG structure with other structures displaying variable arm densities co-existing in solution, affirming high flexibility of arm-connecting linkers. Furthermore, we showed phase plate imaging enables reliable structure determination of Fab to sub-nanometer resolution from ab initio, yielding a characteristic two-lobe structure that could be unambiguously docked with crystal structure. Our findings revealed conformation diversity of IgG and demonstrated phase plate was viable for cryo-EM analysis of small proteins without symmetry. This work helps extend cryo-EM boundaries, providing a valuable imaging and structural analysis framework for macromolecules with similar challenging features.

YULINK regulates vascular formation in zebrafish and HUVECs

BACKGROUND: The distinct arterial and venous cell fates are dictated by a combination of various genetic factors which form diverse types of blood vessels such as arteries, veins, and capillaries. We report here that YULINK protein is involved in vasculogenesis, especially venous formation. METHODS: In this manuscript, we employed gene knockdown, yeast two-hybrid, FLIM-FRET, immunoprecipitation, and various imaging technologies to investigate the role of YULINK gene in zebrafish and human umbilical vein endothelial cells (HUVECs). RESULTS: Knockdown of YULINK during the arterial-venous developmental stage of zebrafish embryos led to the defective venous formation and abnormal vascular plexus formation. Knockdown of YULINK in HUVECs impaired their ability to undergo cell migration and differentiation into a capillary-like tube formation. In addition, the phosphorylated EPHB4 was decreased in YULINK knockdown HUVECs. Yeast two-hybrid, FLIM-FRET, immunoprecipitation, as well as imaging technologies showed that YULINK colocalized with endosome related proteins (EPS15, RAB33B or TICAM2) and markers (Clathrin and RHOB). VEGF-induced VEGFR2 internalization was also compromised in YULINK knockdown HUVECs, demonstrating to the involvement of YULINK. CONCLUSION: This study suggests that YULINK regulates vasculogenesis, possibly through endocytosis in zebrafish and HUVECs. Key points Knockdown of YULINK with morpholino in embryos of double transgenic zebrafish exhibited abnormal venous formation. Tube formation and phosphorylated EPHB4 were decreased in YULINK knockdown HUVECs. FLIM-FRET, immunoprecipitation, as well as other imaging technologies showed that YULINK colocalized with endosome related proteins (EPS15, RAB33B and TICAM2) and endosome markers (Clathrin and RHOB). Knockdown of YULINK decreased the internalization of VEGF and VEGFR2 in HUVECs.