RESUMEN
Serine/threonine-protein kinase-like protein ARABIDOPSIS CRINKLY4 (ACR4), a transmembrane protein of Arabidopsis thaliana, plays important roles in cell division and differentiation. Although accumulating studies shed light on the function of ACR4, the structure and catalytic mechanism of ACR4 remain to be elucidated. Here, we report the purification and enzymatic properties of the intracellular kinase domain (residues 464-799) of ACR4 (ACR4IKD). Through Ni-affinity chromatography and gel filter chromatography methods, we successfully obtain high-purity ACR4IKD protein from Escherichia coli. Dynamic light scattering and gel-filtration methods reveal that ACR4IKD distributes with high homogeneity and exists as a monomer in solution. In addition, the ACR4IKD protein has typical kinase activity with myelin basic protein (MBP) as the substrate. Our study may lay the foundation for structure determination of ACR4IKD and further functional research, for example, screening significant substrates of ACR4 in Arabidopsis thaliana.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimología , Proteínas Serina-Treonina Quinasas/metabolismo , Receptores de Superficie Celular/metabolismo , Secuencia de Aminoácidos , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/aislamiento & purificación , Activación Enzimática , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/aislamiento & purificación , Receptores de Superficie Celular/química , Receptores de Superficie Celular/aislamiento & purificaciónRESUMEN
Receptor kinases play important roles in plant growth and development, but only few of them have been functionally characterized in depth. Over the past decade CRINKLY 4 (CR4)-related research has peaked as a result of a newly discovered role of ARABIDOPSIS CR4 (ACR4) in the root. Here, we comprehensively review the available (A)CR4 literature and describe its role in embryo, seed, shoot, and root development, but we also flag an unexpected role in plant defence. In addition, we discuss ACR4 domains and protein structure, describe known ACR4-interacting proteins and substrates, and elaborate on the transcriptional regulation of ACR4 Finally, we address the missing knowledge in our understanding of ACR4 signalling.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas Serina-Treonina Quinasas/genética , Receptores de Superficie Celular/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/inmunología , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Inmunidad de la Planta , 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/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Receptores de Superficie Celular/metabolismo , Semillas/genética , Semillas/crecimiento & desarrollo , Semillas/metabolismoRESUMEN
The shoot apical meristem (SAM) and root apical meristem (RAM) act as pools of stem cells that give rise to aboveground and underground tissues and organs in higher plants, respectively. The CLAVATA3 (CLV3)-WUSCHEL (WUS) negative-feedback loop acts as a core pathway controlling SAM homeostasis, while CLV3/EMBRYO SURROUNDING REGION (ESR) 40 (CLE40) and WUSCHEL-RELATED HOMEOBOX5 (WOX5), homologs of CLV3 and WUS, direct columella stem cell fate. Moreover, CLV3 INSENSITIVE KINASES (CIKs) have been shown to be essential for maintaining SAM homeostasis, whereas whether they regulate the distal root meristem remains to be elucidated. Here, we report that CIKs are indispensable for transducing the CLE40 signal to maintain homeostasis of the distal root meristem. We found that the cik mutant roots displayed disrupted quiescent center and delayed columella stem cell (CSC) differentiation. Biochemical assays demonstrated that CIKs interact with ARABIDOPSIS CRINKLY4 (ACR4) in a ligand-independent manner and can be phosphorylated by ACR4 in vitro. In addition, the phosphorylation of CIKs can be rapidly induced by CLE40, which partially depends on ACR4. Although CIKs act as conserved and redundant regulators in the SAM and RAM, our results demonstrated that they exhibit differentiated functions in these meristems.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Células Vegetales/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal , Células Madre/metabolismo , Arabidopsis/enzimología , Meristema/citología , Meristema/metabolismo , Raíces de Plantas/metabolismo , Receptores de Superficie Celular/metabolismoRESUMEN
The Bi-RADS (Breast Imaging Reporting and Data System) classification developed by the ACR (American College of Radiology) is the classification system for radiological images recommended for breast cancer screening. The ACR 4 microcalcification is an indeterminate or suspected abnormality with 2-95% probability of malignancy, according to studies. This disparity pushed us to conduct this retrospective study of 181 patients in the Department of Obstetrics and Gynecology I at the Hassan II University Hospital, Fez, over a period of 5 years. This study aimed to report the histological results of breast lesions radiologically classified as ACR4 in order to assess their radio-histological correlation and to improve therapeutic approach. All patients underwent breast imaging examinations and then anatomopathologic examination was performed using different techniques. There was a clear predominance of benign lesions with a rate of 62% versus 29% of malignant lesions and only 9% were intermediate lesions. Adenofibroma was the most common histological finding (30% of cases), invasive ductal carcinoma was the most frequent malignant lesion (17% of cases). We performed a literature review which showed that our results were in line with findings of other studies, with a positive predictive value of 29%. Nevertheless, ACR classification divided into subcategories 4a, b and c should be used due to the significant number of unnecessary surgical interventions.
Asunto(s)
Enfermedades de la Mama/diagnóstico por imagen , Neoplasias de la Mama/diagnóstico por imagen , Calcinosis/diagnóstico por imagen , Adenofibroma/diagnóstico por imagen , Adenofibroma/epidemiología , Adenofibroma/patología , Adolescente , Adulto , Anciano , Enfermedades de la Mama/epidemiología , Enfermedades de la Mama/patología , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/patología , Calcinosis/epidemiología , Calcinosis/patología , Carcinoma Intraductal no Infiltrante/diagnóstico por imagen , Carcinoma Intraductal no Infiltrante/epidemiología , Carcinoma Intraductal no Infiltrante/patología , Femenino , Hospitales Universitarios , Humanos , Tamizaje Masivo/métodos , Persona de Mediana Edad , Marruecos/epidemiología , Valor Predictivo de las Pruebas , Estudios Retrospectivos , Adulto JovenRESUMEN
The optimal kinase activity of plant receptor-like kinases (RLKs) is often regulated by autophosphorylation of specific sites. Many of these phosphorylated residues then serve as recruiting sites for downstream interacting proteins. Therefore, identification of the phosphosites can be an important first step in delineating the signaling network. This chapter describes a protocol for identification of phosphorylated residues by mass spectrometry as well as a protocol to determine if an interacting partner can be phosphorylated in vitro.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Mapeo de Interacción de Proteínas/métodos , Procesamiento Proteico-Postraduccional , Proteínas Serina-Treonina Quinasas/genética , Receptores de Superficie Celular/genética , Secuencia de Aminoácidos , Arabidopsis/enzimología , Proteínas de Arabidopsis/metabolismo , Sitios de Unión , Cromatografía de Afinidad/métodos , Cromatografía Liquida/métodos , Expresión Génica , Isoenzimas/genética , Isoenzimas/metabolismo , Mutagénesis Sitio-Dirigida , Fosforilación , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismo , Receptores de Superficie Celular/metabolismo , Espectrometría de Masas en Tándem/métodosRESUMEN
Formative cell divisions generate new cell types and tissues during development, and are controlled by receptor kinase signalling pathways. The phosphatase PP2A has now been shown to be both a target and positive regulator of the receptor kinase ACR4, thus creating a feed-forward loop that serves to establish new cell fates.