Search

Summary: Alternative splicing of pre‐mRNAs is crucial for plant growth and development. Serine/arginine‐rich (SR) proteins are a conserved family of RNA‐binding proteins that are critical for both constitutive and alternative splicing. However, how phosphorylation of SR proteins regulates gene transcription and alternative splicing during plant development is poorly understood.We found that the Arabidopsis thaliana L. SR protein‐specific kinase II family proteins (SRPKIIs) play an important role in plant development, including flowering. SRPKIIs regulate the phosphorylation status of a subset of specific SR proteins, including SR45 and SC35, which subsequently mediates their subcellular localization.A phospho‐dead SR45 mutant inhibits the assembly of the apoptosis‐and splicing‐associated protein complex and thereby upregulates the expression of FLOWERING LOCUS C (FLC) via epigenetic modification. The splicing efficiency of FLC introns was significantly increased in the shoot apex of the srpkii mutant. Transcriptomic analysis revealed that SRPKIIs regulate the alternative splicing of c. 400 genes, which largely overlap with those regulated by SR45 and SC35‐SCL family proteins.In summary, we found that Arabidopsis SRPKIIs specifically affect the phosphorylation status of a subset SR proteins and regulate the expression and alternative splicing of FLC to control flowering time. [ABSTRACT FROM AUTHOR]

We report the first example of selective PdII‐catalyzed tertiary C−H activation of cyclobutylmethyl ketones using a transient directing group. An electron‐deficient 2‐pyridone ligand was identified as the optimal external ligand to enable tertiary C−H activation. A variety of cyclobutylmethyl ketones bearing quaternary carbon centers was readily accessed without preinstalling internal directing groups in up to 81 % yield and >95 : 5 regioisomeric ratios of tertiary C−H arylation to β‐methylene (β‐methyl) or γ‐C−H arylation. [ABSTRACT FROM AUTHOR]

Long noncoding RNAs (lncRNAs) can compete with endogenous RNAs to modulate the gene expression and contribute to oncogenesis and tumor metastasis. lncRNA NKX2‐1‐AS1 (NKX2‐1 antisense RNA 1) plays a pivotal role in cancer progression and metastasis; however, the contribution of aberrant expression of NKX2‐1‐AS1 and the mechanism by which it functions as a competing endogenous RNA (ceRNA) in gastric cancer (GC) remains elusive. NKX2‐1‐AS1 expression was detected in paired tumor and nontumor tissues of 178 GC patients by quantitative reverse transcription PCR (qRT‐PCR). Using loss‐of‐function and gain‐of‐function experiments, the biological functions of NKX2‐1‐AS1 were evaluated both in vitro and in vivo. Further, to assess that NKX2‐1‐AS1 regulates angiogenic processes, tube formation and co‐culture assays were performed. RNA binding protein immunoprecipitation (RIP) assay, a dual‐luciferase reporter assay, quantitative PCR, Western blot, and fluorescence in situ hybridization (FISH) assays were performed to determine the potential molecular mechanism underlying this ceRNA. The results indicated that NKX2‐1‐AS1 expression was upregulated in GC cell lines and tumor tissues. Overexpression of NKX2‐1‐AS1 was significantly associated with tumor progression and enhanced angiogenesis. Functionally, NKX2‐1‐AS1 overexpression promoted GC cell proliferation, metastasis, invasion, and angiogenesis, while NKX2‐1‐AS1 knockdown restored these effects, both in vitro and in vivo. RIP and dual‐luciferase assays revealed that the microRNA miR‐145‐5p is a direct target of NKX2‐1‐AS1 and that NKX2‐1‐AS1 serves as a ceRNA to sponge miRNA and regulate angiogenesis in GC. Moreover, serpin family E member 1 (SERPINE1) is an explicit target for miR‐145‐5p; besides, the NKX2‐1‐AS1/miR‐145‐5p axis induces the translation of SERPINE1, thus activating the VEGFR‐2 signaling pathway to promote tumor progression and angiogenesis. NKX2‐1‐AS1 overexpression is associated with enhanced tumor cell proliferation, angiogenesis, and poor prognosis in GC. Collectively, NKX2‐1‐AS1 functions as a ceRNA to miR‐145‐5p and promotes tumor progression and angiogenesis by activating the VEGFR‐2 signaling pathway via SERPINE1. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen peroxide (H2O2) is generated in many metabolic processes. As a signaling molecule, H2O2 plays important roles in plant growth and development, as well as environmental stress response. In Arabidopsis, there are three catalase genes, CAT1, CAT2, and CAT3. The encoded catalases are predominately peroxisomal proteins and are critical for scavenging H2O2. Since CAT1 and CAT3 are linked on chromosome 1, it has been almost impossible to generate cat1/3 and cat1/2/3 mutants by traditional genetic tools. In this study, we constructed cat1/3 double mutants and cat1/2/3 triple mutants by CRISPR/Cas9 to investigate the role of catalases. The cat1/2/3 triple mutants displayed severe redox disturbance and growth defects under physiological conditions compared with wild‐type and the cat2/3 double mutants. Transcriptome analysis showed a more profound transcriptional response in the cat1/2/3 triple mutants compared to the cat2/3 mutants. These differentially expressed genes are involved in plant growth regulation as well as abiotic and biotic stress responses. In addition, expression of OXI1 (OXIDATIVE SIGNAL INDUCIBLE 1) and several MAPK cascade genes were changed dramatically in the catalase triple mutant, suggesting that H2O2 produced in peroxisomes could serve as a peroxisomal retrograde signal. [ABSTRACT FROM AUTHOR]