Comprehensive analysis of the Ppatg3 mutant reveals that autophagy plays important roles in gametophore senescence in Physcomitrella patens

Identification of a novel gene, Bryophyte Co-retained Gene 1, that has a positive role in desiccation tolerance in the moss Physcomitrium patens

The moss Physcomitrium patens is a model system for the evolutionary study of land plants, and as such, it may contain as yet unannotated genes with functions related to the adaptation to water deficiency that was required during the water-to-land transition. In this study, we identified a novel gene, Bryophyte Co-retained Gene 1 (BCG1), in P. patens that is responsive to dehydration and rehydration. Under de- and rehydration treatments, BCG1 was significantly co-expressed with DHNA, which encodes a dehydrin (DHN). Examination of previous microarray data revealed that BCG1 is highly expressed in spores, archegonia (female reproductive organ), and mature sporophytes. In addition, the bcg1 mutant showed reduced dehydration tolerance, and this was accompanied by a relatively low level of chlorophyll content during recovery. Comprehensive transcriptomics uncovered a detailed set of regulatory processes that were affected by the disruption to BCG1. Experimental evidence showed that BCG1 might function in antioxidant activity, the abscisic acid pathway, and in intracellular Ca2+ homeostasis to resist desiccation. Overall, our results provide insights into the role of a bryophyte co-retained gene in desiccation tolerance.

Cell death in bryophytes: emerging models to study core regulatory modules and conserved pathways

This review summarizes recent progress in our current understanding of the mechanisms underlying the cell death pathways in bryophytes, focusing on conserved pathways and particularities in comparison to angiosperms. Regulated cell death (RCD) plays key roles during essential processes along the plant life cycle. It is part of specific developmental programmes and maintains homeostasis of the organism in response to unfavourable environments. Bryophytes could provide valuable models to study developmental RCD processes as well as those triggered by biotic and abiotic stresses. Some pathways analogous to those present in angiosperms occur in the gametophytic haploid generation of bryophytes, allowing direct genetic studies. In this review, we focus on such RCD programmes, identifying core conserved mechanisms and raising new key questions to analyse RCD from an evolutionary perspective.

Overexpression of CsATG3a improves tolerance to nitrogen deficiency and increases nitrogen use efficiency in arabidopsis

Nitrogen (N) is a major nutrition element for tea plant. However, application of high levels of N negatively causes environmental problems. Therefore, improved N use efficiency (NUE) of tea plant will be highly desirable and crucial for sustainable tea cultivation. Autophagy plays a central role in N recycling and holds potential to improve N utilization, and many AuTophaGy-related genes (ATGs) are involved in the autophagy process. Here, CsATG3a was identified from Camellia sinensis, and the functions involved in N utilization was characterized in arabidopsis (Arabidopsis thaliana). The transcript level of CsATG3a in tea leaves increases with their maturity. Relative to the wild type (WT) arabidopsis, two CsATG3a-overexpressing (CsATG3a-OE) lines exhibited improved vegetative growth, delayed reproductive stage, and upregulated expression of AtATGs (AtATG3, AtATG5 and AtATG8b) in a low N (LN) hydroponic condition. The expression levels of AtNRT1.1, AtNRT2.1, AtNRT2.2, AtAMT1.1 and AtAMT1.3 for N uptake and transport in roots were all significantly higher in CsATG3a-OE lines compared with those in the WT under LN. Meanwhile, the overexpression of CsATG3a in arabidopsis also increased N and dry matter allocation into both rosette leaves and roots under LN. Additionally, compared with WT, improved HI (harvest index), NHI (N harvest index), NUtE (N utilization efficiency) and NUE (N use efficiency) of CsATG3a-OE lines were further confirmed in a low-N soil cultured experiment. Together, these results concluded that CsATG3a is involved in N recycling and enhances tolerance to LN, indicating that CsATG3a holds potential promise to improve NUE in tea plant.

Autophagy modulates growth and development in the moss Physcomitrium patens

Physcomitrium patens apical growing protonemal cells have the singularity that they continue to undergo cell divisions as the plant develops. This feature provides a valuable tool to study autophagy in the context of a multicellular apical growing tissue coupled to development. Herein, we showed that the core autophagy machinery is present in the moss P. patens, and characterized the 2D and 3D growth and development of atg5 and atg7 loss-of-function mutants under optimal and nutrient-deprived conditions. Our results showed that 2D growth of the different morphological and functional protonemata apical growing cells, chloronema and caulonema, is differentially modulated by this process. These differences depend on the protonema cell type and position along the protonemal filament, and growth condition. As a global plant response, the absence of autophagy favors the spread of the colony through protonemata growth at the expense of a reduction of the 3D growth, such as the buds and gametophore development, and thus the adult gametophytic and reproductive phases. Altogether this study provides valuable information suggesting that autophagy has roles during apical growth with differential responses within the cell types of the same tissue and contributes to life cycle progression and thus the growth and development of the 2D and 3D tissues of P. patens.

Apelin/APJ signaling activates autophagy to promote human lung adenocarcinoma cell migration

AIMS

Beclin1(BECN1) is known as an autophagy-related protein and the expression is promoted by apelin in lung adenocarcinoma cells, suggesting that apelin activates autophagy in lung adenocarcinoma. However, the functions of apelin-induced autophagy in lung adenocarcinoma tumorigenesis and deterioration are still unknown. Thus, this study aims to investigate the effects of apelin-induced autophagy on lung adenocarcinoma tumorigenesis and deterioration.

MAIN METHODS

Protein expression of exogenous genes were detected by Western blotting analysis. Lung adenocarcinoma cell migration was assessed with cell migration assays. Autophagy was measured with quantification of GFP-LC3 or RFP-GFP-LC3 puncta using fluorescence microscopy in cells by an observed blinded to experimental condition and by western blot analysis of LC3 and p62 in cell lysates as well as autophagy flux. Immunofluorescence staining was performed in human lung adenocarcinoma A549 cells with p-cofilin antibody. The proteins expression in cancer specimens were examined with immunohistochemistry.

KEY FINDINGS

Here, we reveal that apelin induces autophagy activation in lung adenocarcinoma. Apelin/APJ regulates BECN1 transcription via HIF1A. Apelin/APJ-activated autophagy promotes lung adenocarcinoma cell migration. Moreover, treatment with autophagy inhibitors significantly decreases apelin/APJ-induced lung adenocarcinoma cell migration. Evaluation of patient samples of lung adenocarcinoma reveals an association between APJ with BECN1 expression and a poor prognosis.

SIGNIFICANCE

Our studies demonstrate that apelin-induced autophagy promotes lung adenocarcinoma cell migration which suggests a potential therapeutic target for lung adenocarcinoma.