RESUMEN
We are entering an exciting century in the study of the plant organelles in the endomembrane system. Over the past century, especially within the past 50 years, tremendous advancements have been made in the complex plant cell to generate a much clearer and informative picture of plant organelles, including the molecular/morphological features, dynamic/spatial behavior, and physiological functions. Importantly, all these discoveries and achievements in the identification and characterization of organelles in the endomembrane system would not have been possible without: (1) the innovations and timely applications of various state-of-art cell biology tools and technologies for organelle biology research; (2) the continuous efforts in developing and characterizing new organelle markers by the plant biology community; and (3) the landmark studies on the identification and characterization of the elusive organelles. While molecular aspects and results for individual organelles have been extensively reviewed, the development of the techniques for organelle research in plant cell biology is less appreciated. As one of the ASPB Centennial Reviews on "organelle biology," here we aim to take a journey across a century of organelle biology research in plants by highlighting the important tools (or landmark technologies) and key scientists that contributed to visualize organelles. We then highlight the landmark studies leading to the identification and characterization of individual organelles in the plant endomembrane systems.
Asunto(s)
Orgánulos , Plantas , Orgánulos/metabolismo , Orgánulos/fisiología , Plantas/metabolismo , Historia del Siglo XX , Historia del Siglo XXI , Células Vegetales/fisiología , Membranas Intracelulares/metabolismoRESUMEN
The primary cell wall is a fundamental plant constituent that is flexible but sufficiently rigid to support the plant cell shape. Although many studies have demonstrated that reactive oxygen species (ROS) serve as important signaling messengers to modify the cell wall structure and affect cellular growth, the regulatory mechanism underlying the spatial-temporal regulation of ROS activity for cell wall maintenance remains largely unclear. Here, we demonstrate the role of the Arabidopsis (Arabidopsis thaliana) multicopper oxidase-like protein skewed 5 (SKU5) and its homolog SKU5-similar 1 (SKS1) in root cell wall formation through modulating ROS homeostasis. Loss of SKU5 and SKS1 function resulted in aberrant division planes, protruding cell walls, ectopic deposition of iron, and reduced nicotinamide adeninedinucleotide phosphate (NADPH) oxidase-dependent ROS overproduction in the root epidermis-cortex and cortex-endodermis junctions. A decrease in ROS level or inhibition of NADPH oxidase activity rescued the cell wall defects of sku5 sks1 double mutants. SKU5 and SKS1 proteins were activated by iron treatment, and iron over-accumulated in the walls between the root epidermis and cortex cell layers of sku5 sks1. The glycosylphosphatidylinositol-anchored motif was crucial for membrane association and functionality of SKU5 and SKS1. Overall, our results identified SKU5 and SKS1 as regulators of ROS at the cell surface for regulation of cell wall structure and root cell growth.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Pared Celular , Raíces de Plantas , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Pared Celular/metabolismo , Hierro/metabolismo , NADPH Oxidasas/genética , NADPH Oxidasas/metabolismo , Oxidación-Reducción , Oxidorreductasas/genética , Oxidorreductasas/metabolismo , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Root hairs are single-cell projections in the root epidermis. The presence of root hairs greatly expands the root surface, which facilitates soil anchorage and the absorption of water and nutrients. Root hairs are also the ideal system to study the mechanism of polar growth. Previous research has identified many important factors that control different stages of root hair development. Using a chemical genetics screen, in this study we report the identification of a steroid molecule, RHP1, which promotes root hair growth at nanomolar concentrations without obvious change of other developmental processes. We further demonstrate that RHP1 specifically affects tip growth with no significant influence on cell fate or planar polarity. We also show that RHP1 promotes root hair tip growth via acting upstream of the RHD6-RSL4-dependent transcriptional pathway and ROP GTPase-guided local signaling. Finally, we demonstrate that RHP1 exhibits a wide range of effects on different plant species in both monocots and dicots. This study of RHP1 will not only help to dissect the mechanism of root hair tip growth, but also provide a new tool to modify root hair growth in different plant species.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Diferenciación Celular , Raíces de Plantas , Transducción de SeñalRESUMEN
Damaged mitochondria, a key factor in liver fibrosis, can be removed by the mitophagy pathway to maintain homeostasis of the intracellular environment to alleviate the development of fibrosis. PINK1 (PTEN-induced kinase 1) and NIPSNAP1 (nonneuronal SNAP25-like protein 1), which cooperatively regulate mitophagy, have been predicted to include the sites of lysine acetylation related to SIRT3 (mitochondrial deacetylase sirtuin 3). Our study aimed to discuss whether SIRT3 deacetylates PINK1 and NIPSNAP1 to regulate mitophagy in liver fibrosis. Carbon tetrachloride (CCl4 )-induced liver fibrosis as an in vivo model and LX-2 cells as activated cells were used to simulate liver fibrosis. SIRT3 expression was significantly decreased in mice in response to CCl4 , and SIRT3 knockout in vivo significantly deepened the severity of liver fibrosis, as indicated by increased α-SMA and Col1a1 levels both in vivo and in vitro. SIRT3 overexpression decreased α-SMA and Col1a1 levels. Furthermore, SIRT3 significantly regulated mitophagy in liver fibrosis, as demonstrated by LC3-â ¡/â and p62 expression and colocalization between TOM20 and LAMP1. Importantly, PINK1 and NIPSNAP1 expression was also decreased in liver fibrosis, and PINK1 and NIPSNAP1 overexpression significantly improved mitophagy and attenuated ECM production. Furthermore, after simultaneously interfering with PINK1 or NIPSNAP1 and overexpressing SIRT3, the effect of SIRT3 on improving mitophagy and alleviating liver fibrosis was disrupted. Mechanistically, we show that SIRT3, as a mitochondrial deacetylase, specifically regulates the acetylation of PINK1 and NIPSNAP1 to mediate the mitophagy pathway in liver fibrosis. SIRT3-mediated PINK1 and NIPSNAP1 deacetylation is a novel molecular mechanism in liver fibrosis.
Asunto(s)
Cirrosis Hepática , Sirtuina 3 , Animales , Ratones , Cirrosis Hepática/genética , Cirrosis Hepática/metabolismo , Mitofagia , Proteínas Quinasas/metabolismo , Sirtuina 3/genética , Sirtuina 3/metabolismo , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
In Alzheimer's disease, hypochlorous acid involved in the clearance of invading bacteria or pathogens and butyrylcholinesterase engaged in the hydrolysis of the neurotransmitter acetylcholine are relatively significantly altered. However, there are few dual detection probes for hypochlorous acid and butyrylcholinesterase. In addition, single-response probes suffer from serious off-target effects and near-infrared probes do not easily penetrate the blood-brain barrier due to their excessive molecular weight. In this work, we constructed a two-photon fluorescent probe that recognizes hypochlorous acid and butyrylcholinesterase based on a dual-lock strategy. The thiocarbonyl group is oxidized in the presence of hypochlorous acid, and the hydrolysis occurs at the 7-position ester bond in the existence of butyrylcholinesterase, releasing a strongly fluorescent fluorophore, 4-methylumbelliferone. Excellent imaging was performed in PC12 cells using this probe, and deep two-photon imaging was observed in the brains of AD mice after tail vein injection with this probe. It indicates that the probe can provide a promising tool for the more precise diagnosis of Alzheimer's disease.
Asunto(s)
Enfermedad de Alzheimer , Ratones , Animales , Enfermedad de Alzheimer/diagnóstico por imagen , Butirilcolinesterasa/metabolismo , Ácido Hipocloroso , Colorantes Fluorescentes/química , Encéfalo/metabolismoRESUMEN
The homotypic fusion and protein sorting (HOPS) complex is a conserved, multi-subunit tethering complex in eukaryotic cells. In yeast and mammalian cells, the HOPS subunit vacuolar protein sorting-associated protein 41 (VPS41) is recruited to late endosomes after Ras-related protein 7 (Rab7) activation and is essential for vacuole fusion. However, whether VPS41 plays conserved roles in plants is not clear. Here, we demonstrate that in the model plant Arabidopsis (Arabidopsis thaliana), VPS41 localizes to distinct condensates in root cells in addition to its reported localization at the tonoplast. The formation of condensates does not rely on the known upstream regulators but depends on VPS41 self-interaction and is essential for vegetative growth regulation. Genetic evidence indicates that VPS41 is required for both homotypic vacuole fusion and cargo sorting from the adaptor protein complex 3, Rab5, and Golgi-independent pathways but is dispensable for the Rab7 cargo inositol transporter 1. We also show that VPS41 has HOPS-independent functions in vacuolar transport. Taken together, our findings indicate that Arabidopsis VPS41 is a unique subunit of the HOPS complex that carries out plant-specific roles in both vacuolar transport and developmental regulation.
Asunto(s)
Arabidopsis , Proteínas de Plantas , Proteínas de Transporte Vesicular , Animales , Arabidopsis/genética , Arabidopsis/metabolismo , Endosomas/metabolismo , Mamíferos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transporte de Proteínas/fisiología , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Vacuolas/metabolismo , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismoRESUMEN
Gastric ulcers are a common clinical presentation affecting anyone, regardless of their age or gender. Nanoparticles (NPs) containing Bletilla striata polysaccharide (BSP) and omeprazole (OME) were investigated in the study for their therapeutic effect on gastric ulcers. Ethanol-induced gastric ulcers in rats (240 ± 30 g) were established. Our OME-BSP NPs were more stable than free OME in the acidic environment and can increase the absorption of OME in rat stomach, which was confirmed by in situ gastric absorption and distribution experiments. The extended blood circulation of OME-BSP NPs was also observed in rats with gastric ulcer. More importantly, OME-BSP NPs not only decreased the area of gastric ulcer and inhibited gastric acid secretion but also reversed gastric tissue damage and cell apoptosis, as revealed by HE and TUNEL staining. Subsequent SOD, MDA, PGE2, IL-6, and TNF-α tests further verified the superiority of OME-BSP NPs against rat gastric ulcer, which properly originated from superior antioxidant and anti-inflammatory effects. As a result, our OME-BSP NPs' drug delivery system improved the stability and absorption of OME in the rat stomach and achieved targeted treatment of gastric ulcers.
Asunto(s)
Omeprazol , Úlcera Gástrica , Ratas , Animales , Omeprazol/uso terapéutico , Úlcera Gástrica/inducido químicamente , Úlcera Gástrica/tratamiento farmacológico , Etanol/efectos adversos , Polisacáridos/farmacología , Polisacáridos/uso terapéuticoRESUMEN
BACKGROUND: Facial rejuvenation is becoming more and more popular, particularly among middle-aged persons. There are currently many techniques for improving the aforementioned situations, but each has its drawbacks. Our study aimed to discuss the treatment effect of a composited technique for reversing both lower eyelid and midface aging. METHODS: The patient's face was designed and measured before surgery. During surgery, a traditional lower blepharoplasty incision was made. The layer between the orbital septum and the orbicularis oculi muscle was separated to approximately 4-5 mm below the infraorbital, then the orbital septum and orbicularis retaining ligament were found to be released. A self-made suspension curving needle subconsciously passed through the brim of the superficial cheek fat pad via the "U-type" path and raised them to the proper location. Then sutured them to the infraorbital rim periosteum, as well as the suborbicularis oculi fat (SOOF) and the orbital septum fat. Secured the outside canthus to keep the lower lid position stable. RESULTS: From February 2020 to November 2022, 106 patients underwent the new surgical procedure and were successfully followed up for 20 ± 6.5 months postoperatively. The mean GAIS score was 2.42 ± 0.78, patient satisfaction rate was 95%. All of the Barton grades were decreased. The nasal base level suspension points were elevated to a level of 5 ± 2 mm. 3D measurement data revealed significant improvements. CONCLUSIONS: The composited technique is a safe and effective way to reverse the aging of the lower eyelid and midface.
Asunto(s)
Blefaroplastia , Elevación , Persona de Mediana Edad , Humanos , Envejecimiento , Párpados/cirugía , Blefaroplastia/métodos , Cara/cirugía , Tejido AdiposoRESUMEN
Microvascular invasion (MVI) is a crucial risk factor related to the metastasis of hepatocellular carcinoma (HCC), but the underlying mechanisms remain to be revealed. Characterizing the inherent mechanisms of MVI may aid in the development of effective treatment strategies to improve the prognosis of HCC patients with metastasis. Through the Gene Expression Omnibus (GEO) database, we identified that small nuclear ribonucleoprotein polypeptide A (SNRPA) was related to MVI in HCC. SNRPA was overexpressed in MVI-HCC and correlated with poor patient survival. Mechanistically, SNRPA promoted the epithelial-mesenchymal transition (EMT)-like process for HCC cells to accelerate metastasis by activating the NOTCH1/Snail pathway in vitro and in vivo. Importantly, circSEC62 upregulated SNRPA expression in HCC cells via miR-625-5p sponging. Taking these results together, our study identified a novel regulatory mechanism among SNRPA, miR-625-5p, circSEC62 and the NOTCH1/Snail pathway in HCC, which promoted metastasis of HCC and may provide effective suggestions for improving the prognosis of HCC patients with metastasis.
Asunto(s)
Carcinoma Hepatocelular , Neoplasias Hepáticas , MicroARNs , Metástasis de la Neoplasia , Factores de Empalme de ARN , ARN Circular , Humanos , Carcinoma Hepatocelular/patología , Línea Celular Tumoral , Movimiento Celular , Proliferación Celular , Transición Epitelial-Mesenquimal/genética , Regulación Neoplásica de la Expresión Génica , Neoplasias Hepáticas/patología , MicroARNs/genética , Péptidos/genética , Péptidos/metabolismo , Receptor Notch1/genética , Receptor Notch1/metabolismo , Factores de Empalme de ARN/genética , Factores de Empalme de ARN/metabolismo , ARN Circular/metabolismoRESUMEN
To adapt to the diverse array of biotic and abiotic cues, plants have evolved sophisticated mechanisms to sense changes in environmental conditions and modulate their growth. Growth-promoting hormones and defence signalling fine tune plant development antagonistically. During host-pathogen interactions, this defence-growth trade-off is mediated by the counteractive effects of the defence hormone salicylic acid (SA) and the growth hormone auxin. Here we revealed an underlying mechanism of SA regulating auxin signalling by constraining the plasma membrane dynamics of PIN2 auxin efflux transporter in Arabidopsis thaliana roots. The lateral diffusion of PIN2 proteins is constrained by SA signalling, during which PIN2 proteins are condensed into hyperclusters depending on REM1.2-mediated nanodomain compartmentalisation. Furthermore, membrane nanodomain compartmentalisation by SA or Remorin (REM) assembly significantly suppressed clathrin-mediated endocytosis. Consequently, SA-induced heterogeneous surface condensation disrupted asymmetric auxin distribution and the resultant gravitropic response. Our results demonstrated a defence-growth trade-off mechanism by which SA signalling crosstalked with auxin transport by concentrating membrane-resident PIN2 into heterogeneous compartments.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Ácidos Indolacéticos , Lípidos , Proteínas de Plantas , Raíces de Plantas , Ácido SalicílicoRESUMEN
Molecular imaging significantly transforms the field of biomedical science and facilitates the visualization, characterization, and quantification of biologic processes. However, it is still challenging to monitor cell localization in vivo, which is essential to the study of tumor metastasis and in the development of cell-based therapies. While most conventional small-molecule fluorescent probes cannot afford durable cell labeling, transfection of cells with fluorescent proteins is limited by their fixed fluorescence, poor tissue penetration, and interference of autofluorescence background. Here, a bioresponsive near-infrared fluorescent probe is reported as facile and reliable tool for real-time cell tracking in vivo. The design of this probe relies on a new phenomenon observed upon fluorobenzene-conjugated fluorescent dyes, which can form complexes with cytosolic glutathione and actively translocates to lysosomes, exhibiting enhanced and stable cell labeling. Fluorobenzene-coupled hemicyanine, a near-infrared fluorophore manifests to efficiently staining tumor cells without affecting their invasive property and enables persistent monitoring of cell migration in metastatic tumor murine models at high resolution for one week. The method of fluorobenzene functionalization also provides a simple and universal "add-on" strategy to render ordinary fluorescent probes suitable for long-term live-cell tracking, for which currently there is a deficit of suitable molecular tools.
Asunto(s)
Rastreo Celular , Colorantes Fluorescentes , Animales , Lisosomas , Ratones , Imagen Molecular , Coloración y EtiquetadoRESUMEN
The endomembrane system is an interconnected network required to establish signal transduction, cell polarity, and cell shape in response to developmental or environmental stimuli. In the model plant Arabidopsis thaliana, there are numerous markers to visualize polarly localized plasma membrane proteins utilizing endomembrane trafficking. Previous studies have shown that the large ARF-GEF GNOM plays a key role in the establishment of basal (rootward) polarity, whereas the apically (shootward) polarized membrane proteins undergo sorting via different routes. However, the mechanism that maintains apical polarity is largely unknown. Here, we used a chemical genomic approach and identified the compound endosidin 16 (ES16), which perturbed apically localized plasma membrane proteins without affecting basal polarity. We demonstrated that ES16 is an inhibitor for recycling of apical, lateral, and nonpolar plasma membrane proteins as well as biosynthetic secretion, leaving the basal proteins as the only exceptions not subject to ES16 inhibition. Further evidence from pharmaceutical and genetic data revealed that ES16 effects are mediated through the regulation of small GTPase RabA proteins and that RabA GTPases work in concert with the BIG clade ARF-GEF to modulate the nonbasal trafficking. Our results reveal that ES16 defines a distinct pathway for endomembrane sorting routes and is essential for the establishment of cell polarity.
Asunto(s)
Arabidopsis/metabolismo , Membrana Celular/metabolismo , Polaridad Celular/fisiología , Transducción de Señal , Arabidopsis/citología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Membrana Celular/ultraestructura , Polaridad Celular/efectos de los fármacos , Polaridad Celular/genética , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/ultraestructura , Factores de Intercambio de Guanina Nucleótido/genética , Factores de Intercambio de Guanina Nucleótido/metabolismo , Immunoblotting , Microscopía Confocal , Microscopía Electrónica de Transmisión , Plantas Modificadas Genéticamente , Transporte de Proteínas/efectos de los fármacos , Quinolonas/química , Quinolonas/farmacología , Plantones/citología , Plantones/genética , Plantones/metabolismo , Proteínas de Unión al GTP rab/genética , Proteínas de Unión al GTP rab/metabolismo , Red trans-Golgi/metabolismo , Red trans-Golgi/ultraestructuraRESUMEN
Boron neutron capture therapy (BNCT) has received extensive attention as noninvasive cell-level oncotherapy for treating solid cancer tumors. However, boron-containing drugs such as l-boronophenylalanine (BPA) and sodium borocaptate have low boron content and/or poor tumor-targeting ability, limiting their application. In this study, we designed and synthesized a series of nontoxic, dual-target boron carriers (B139, B142, and B151) with the ability to accumulate specifically in tumor cells. We found that the B139 uptake into hypoxic tumor regions was high, with a 70-fold boron content compared to BPA. In addition, in vivo observation showed that B139 can be trapped in tumor cells for a prolonged period and maintains an effective therapeutic concentration, with a peak boron concentration of 50.7 µg/g and a high tumor: blood boron ratio of >3, achieving ideal BNCT conditions. Cytotoxicity evaluation in mice further proved that B139 is safe and reliable. Therefore, B139 has great potential for BNCT application as a dual-target, safe, and efficient boron carrier.
Asunto(s)
Terapia por Captura de Neutrón de Boro , Neoplasias/radioterapia , Animales , Boranos/farmacología , Compuestos de Boro/química , Compuestos de Boro/metabolismo , Compuestos de Boro/farmacocinética , Compuestos de Boro/toxicidad , Hipoxia de la Célula , Línea Celular Tumoral , Humanos , Ratones , Nanopartículas/química , Nanopartículas/efectos de la radiación , Nanopartículas/uso terapéutico , Neoplasias/sangre , Neoplasias/enzimología , Neoplasias/metabolismo , Nitroimidazoles/química , Fenilalanina/análogos & derivados , Fenilalanina/farmacología , Distribución Tisular , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Cyclodipeptide 2,5-diketopiperazines (DKP) are privileged structural units present in drugs and natural alkaloids. This work reports a new method for the synthesis of biologically important DKP scaffolds based on an intramolecular nucleophilic α-addition of general amides towards an alkynamide system. The utility of this umpolung cyclization mediated by trimethyl phosphine and l-glutamic acid is highlighted by its application to the concise total syntheses of 6-methoxyspirotryprostatinâ B (the first total synthesis), spirotryprostatinâ A, and spirotryprostatinâ B.
RESUMEN
The exocyst complex regulates the last steps of exocytosis, which is essential to organisms across kingdoms. In humans, its dysfunction is correlated with several significant diseases, such as diabetes and cancer progression. Investigation of the dynamic regulation of the evolutionarily conserved exocyst-related processes using mutants in genetically tractable organisms such as Arabidopsis thaliana is limited by the lethality or the severity of phenotypes. We discovered that the small molecule Endosidin2 (ES2) binds to the EXO70 (exocyst component of 70 kDa) subunit of the exocyst complex, resulting in inhibition of exocytosis and endosomal recycling in both plant and human cells and enhancement of plant vacuolar trafficking. An EXO70 protein with a C-terminal truncation results in dominant ES2 resistance, uncovering possible distinct regulatory roles for the N terminus of the protein. This study not only provides a valuable tool in studying exocytosis regulation but also offers a potentially new target for drugs aimed at addressing human disease.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Endosomas/metabolismo , Exocitosis , Limoninas/metabolismo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Membrana Celular/metabolismo , Secuencia Conservada , Evolución Molecular , Humanos , Estructura Secundaria de ProteínaRESUMEN
Ethylene stimulates the exaggerated hook formation in etiolated seedlings. It has been reported that other phytohormones, such as jasmonate or gibberellins, could inhibit or coordinate hook formation, respectively. However, whether any environmental factors participate in this process is unknown. Here, we show that in darkness, high ambient temperature suppresses the ethylene-triggered exaggerated hook formation in wild-type plants and reduces the hook curvatures in constitutively ethylene responsive mutants. Interestingly, high temperature does not abrogate the activity of the central transcription factor EIN3, suggesting that high temperature acts downstream of ethylene signaling. Next, we show that the natural auxin levels in the hook regions are reduced and their asymmetric distributions are disturbed upon high temperature treatment. To explore the mechanisms for reducing auxin accumulation, we monitor the transcription of several genes encoding auxin biosynthesis related enzymes and find that most YUCCA genes are transcriptionally down-regulated. Finally, we show that the currently reported plant thermo-sensory components in light-grown plants (phytochrome or PIF4) are not sufficient for thermo-sensing in etiolated seedlings. We speculate that in darkness, plants sense high ambient temperature through a distinct mechanism. Taken together, we demonstrate that high temperature suppresses ethylene-induced exaggerated hook formation via the inhibition of local auxin activities.
Asunto(s)
Arabidopsis/crecimiento & desarrollo , Etilenos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Plantones/crecimiento & desarrollo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Unión al ADN , Calor , Ácidos Indolacéticos/metabolismo , Microscopía Confocal , Proteínas Nucleares/metabolismo , Plantones/metabolismo , Factores de Transcripción/metabolismoRESUMEN
The vacuole is the most prominent compartment in plant cells and is important for ion and protein storage. In our effort to search for key regulators in the plant vacuole sorting pathway, ribosomal large subunit 4 (rpl4d) was identified as a translational mutant defective in both vacuole trafficking and normal development. Polysome profiling of the rpl4d mutant showed reduction in polysome-bound mRNA compared with wild-type, but no significant change in the general mRNA distribution pattern. Ribsomal profiling data indicated that genes in the lipid metabolism pathways were translationally down-regulated in the rpl4d mutant. Live imaging studies by Nile red staining suggested that both polar and nonpolar lipid accumulation was reduced in meristem tissues of rpl4d mutants. Pharmacological evidence showed that sterol and sphingolipid biosynthetic inhibitors can phenocopy the defects of the rpl4d mutant, including an altered vacuole trafficking pattern. Genetic evidence from lipid biosynthetic mutants indicates that alteration in the metabolism of either sterol or sphingolipid biosynthesis resulted in vacuole trafficking defects, similar to the rpl4d mutant. Tissue-specific complementation with key enzymes from lipid biosynthesis pathways can partially rescue both vacuole trafficking and auxin-related developmental defects in the rpl4d mutant. These results indicate that lipid metabolism modulates auxin-mediated tissue differentiation and endomembrane trafficking pathways downstream of ribosomal protein function.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Metabolismo de los Lípidos , Proteínas Ribosómicas/metabolismo , Vacuolas/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Genes de Plantas , Prueba de Complementación Genética , Ácidos Indolacéticos/farmacología , Metabolismo de los Lípidos/efectos de los fármacos , Metabolismo de los Lípidos/genética , Lípidos/biosíntesis , Meristema/efectos de los fármacos , Meristema/metabolismo , Modelos Biológicos , Mutación , Especificidad de Órganos/efectos de los fármacos , Especificidad de Órganos/genética , Señales de Clasificación de Proteína , Transporte de Proteínas/efectos de los fármacos , Proteínas Ribosómicas/genética , Vacuolas/efectos de los fármacosRESUMEN
Plant architecture is one of the key factors that affect plant survival and productivity. Plant body structure is established through the iterative initiation and outgrowth of lateral organs, which are derived from the shoot apical meristem and root apical meristem, after embryogenesis. Here we report that ADP1, a putative MATE (multidrug and toxic compound extrusion) transporter, plays an essential role in regulating lateral organ outgrowth, and thus in maintaining normal architecture of Arabidopsis. Elevated expression levels of ADP1 resulted in accelerated plant growth rate, and increased the numbers of axillary branches and flowers. Our molecular and genetic evidence demonstrated that the phenotypes of plants over-expressing ADP1 were caused by reduction of local auxin levels in the meristematic regions. We further discovered that this reduction was probably due to decreased levels of auxin biosynthesis in the local meristematic regions based on the measured reduction in IAA levels and the gene expression data. Simultaneous inactivation of ADP1 and its three closest homologs led to growth retardation, relative reduction of lateral organ number and slightly elevated auxin level. Our results indicated that ADP1-mediated regulation of the local auxin level in meristematic regions is an essential determinant for plant architecture maintenance by restraining the outgrowth of lateral organs.
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Proteínas de Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Meristema/metabolismo , Proteínas de Transporte de Catión Orgánico/genética , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Flores/genética , Flores/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas , Meristema/crecimiento & desarrollo , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Brotes de la Planta/genética , Brotes de la Planta/crecimiento & desarrollo , Brotes de la Planta/metabolismoRESUMEN
The circularly permuted GTPase large subunit GTPase 1 (LSG1) is involved in the maturation step of the 60S ribosome and is essential for cell viability in yeast. Here, an Arabidopsis mutant dig6 (drought inhibited growth of lateral roots) was isolated. The mutant exhibited multiple auxin-related phenotypes, which included reduced lateral root number, altered leaf veins, and shorter roots. Genetic mapping combined with next-generation DNA sequencing identified that the mutation occurred in AtLSG1-2. This gene was highly expressed in regions of auxin accumulation. Ribosome profiling revealed that a loss of function of AtLSG1-2 led to decreased levels of monosomes, further demonstrating its role in ribosome biogenesis. Quantitative proteomics showed that the expression of certain proteins involved in ribosome biogenesis was differentially regulated, indicating that ribosome biogenesis processes were impaired in the mutant. Further investigations showed that an AtLSG1-2 deficiency caused the alteration of auxin distribution, response, and transport in plants. It is concluded that AtLSG1-2 is integral to ribosome biogenesis, consequently affecting auxin homeostasis and plant development.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Proteínas Ribosómicas/genética , Ribosomas/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Mutación , Proteínas Ribosómicas/metabolismoRESUMEN
BACKGROUND: Angiopoietin-like-3 (ANGPTL3) expression is increased in glomerular podocytes of nephrotic syndrome. We hypothesize whether ANGPTL3 plays an important role in podocyte injury and promoting proteinuria. METHODS: Angptl3(+/+) and Angptl3(-/-) female mice on B6;129S5 gene background were injected with adriamycin by tail vein at the dose of 25 mg/Kg to produce nephropathy. Proteinuira was measured and podocytes ultrastructure was observed by electron microscopy. The interaction between ANGPTL3 and intergrin ß3 was analyzed by CO-IP and confocal immunofluorescence. The relative gene and protein expression were analyzed by RT-PCR and western blot. RESULTS: The deletion of ANGPTL3 tremendously attenuates proteinuria (more than a fivefold decrease in albuminuria) and protects podocytes from injury in a mouse model of adriamycin-induced nephropathy. We further demonstrate that ANGPTL3 interacts with and activates podocyte-expressed integrin ß3 and regulate expression of α-actinin-4, which may result in the cytoskeletal rearrangement of podocytes. Additionally, we identify the activation of the ANGPTL3-integrin ß3 signaling pathway in patients with nephrotic syndrome. CONCLUSION: ANGPTL3 might play a crucial role in podocyte injury. Either decreasing ANGPTL3 expression or interfering with the ANGPTL3-integrin ß3 interaction might be benefit for podocyte protection and decrease proteinuira.