ABSTRACT
Brassinosteroids (BRs) form a group of steroidal hormones essential for plant growth, development, and stress responses. BRs are perceived extracellularly by plasma membrane receptor-like kinases that activate an interconnected signal transduction cascade, leading to the transcriptional regulation of BR-responsive genes. TETRATRICOPEPTIDE THIOREDOXIN-LIKE (TTL) genes are specific for land plants, and their encoded proteins are defined by the presence of protein-protein interaction motives, that is, an intrinsic disordered region at the N terminus, six tetratricopeptide repeat domains, and a C terminus with homology to thioredoxins. TTL proteins thus likely mediate the assembly of multiprotein complexes. Phenotypic, molecular, and genetic analyses show that TTL proteins are positive regulators of BR signaling in Arabidopsis (Arabidopsis thaliana). TTL3 directly interacts with a constitutively active BRASSINOSTEROID INSENSITIVE1 (BRI1) receptor kinase, BRI1-SUPPRESSOR1 phosphatase, and the BRASSINAZOLE RESISTANT1 transcription factor and associates with BR-SIGNALING KINASE1, BRASSINOSTEROID INSENSITIVE2 kinases, but not with BRI1-ASSOCIATED KINASE1. A functional TTL3-green fluorescent protein (GFP) shows dual cytoplasmic plasma membrane localization. Depleting the endogenous BR content reduces plasma membrane localization of TTL3-GFP, while increasing BR content causes its plasma membrane relocalization, where it strengthens the association of BR signaling components. Our results reveal that TTL proteins promote BR responses and suggest that TTL proteins may function as scaffold proteins by bringing together cytoplasmic and plasma membrane BR signaling components.
Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Brassinosteroids/metabolism , Arabidopsis/genetics , Cell Membrane/metabolism , Gene Expression Regulation, Plant/genetics , Gene Expression Regulation, Plant/physiology , Membrane Proteins/metabolism , Signal Transduction/genetics , Signal Transduction/physiologyABSTRACT
We are developing molecular approaches to study the growth and development of woody plants. As part of our research efforts, we report the molecular cloning and characterization of PsRLK here, a cDNA from the conifer Scots pine (Pinus sylvestris L.) encoding a polypeptide similar to the receptor protein kinases described in angiosperms. A full-length clone was isolated from a cDNA library constructed with poly (A)+ enriched RNA prepared from germinating pine seeds. Characterization of the isolated sequence revealed that it contains multiple leucine-rich repeats in the N-terminal region and a characteristic Ser/Thr protein kinase domain in the C-terminal region. N- and C-terminal conserved domains are separated by a putative membrane spanning sequence. PsRLK protein is encoded by a single gene in the pine genome. A comparison of the pine sequence with the LRR-RLKs from Arabidopsis revealed that PsRLK is phylogenetically related to the LRR XI subfamily members. RT-PCR analyses of transcript abundance in pine tissues suggest that the gene expression pattern of PsRLK reflects the plant body formation programme, with increased levels during development of pine seedlings. The precise localization of PsRLK transcripts revealed that gene expression was restricted to specialized phloem cells suggesting a possible function of the putative receptor-like protein kinase in this particular vascular element.
Subject(s)
Pinus sylvestris/enzymology , Plant Proteins/genetics , Protein Serine-Threonine Kinases/genetics , Receptors, Cell Surface/genetics , Amino Acid Sequence , Cloning, Molecular , Gene Library , Molecular Sequence Data , Phylogeny , Pinus sylvestris/anatomy & histology , Pinus sylvestris/genetics , Plant Proteins/chemistry , Plant Proteins/metabolism , Protein Serine-Threonine Kinases/chemistry , Protein Serine-Threonine Kinases/metabolism , Protein Structure, Tertiary , RNA, Messenger/analysis , RNA, Messenger/metabolism , Receptors, Cell Surface/chemistry , Receptors, Cell Surface/metabolism , Seedlings/anatomy & histology , Seedlings/enzymology , Seedlings/growth & development , Sequence AlignmentABSTRACT
La hipertensión arterial es una de las enfermedades que más se presenta en el mundo de hoy y constituye uno de los principales factores que aumenta el riesgo de padecer enfermedades cerebrovasculares y cardiovasculares. Para esta investigación se estudió una muestra de 78 pacientes del consultorio médico de familia 96-2 del Policlínico Chiqui Gómez Lubián, de ambos sexos y más de 60 años, la cual fue dividida en tres subgrupos y quedaron excluidos los pacientes diagnosticados como hipertensos. Se realizó la prueba del esfuerzo sostenido, que se correlacionó con factores de riesgo de hipertensión arterial (antecedentes patológicos personales, antecedentes patológicos familiares, sedentarismo, hábito de fumar, consumo de alcohol, ingestión de sal y obesidad), con el objetivo de evaluar la incidencia de estos factores y su relación con la prueba isométrica. Se obtuvo respuesta presora significativa a esta prueba en los tres grupos de edades y en relación directa con los factores de riesgo evaluados; basado en ello se aplicó un régimen preventivo para mantener una elevada calidad de vida(AU)
