RESUMO
Plakophilin 1 (PKP1), a member of the p120ctn subfamily of the armadillo (ARM)-repeat-containing proteins, is an important structural component of cell-cell adhesion scaffolds although it can also be ubiquitously found in the cytoplasm and the nucleus. RYBP (RING 1A and YY1 binding protein) is a multifunctional intrinsically disordered protein (IDP) best described as a transcriptional regulator. Both proteins are involved in the development and metastasis of several types of tumors. We studied the binding of the armadillo domain of PKP1 (ARM-PKP1) with RYBP by using in cellulo methods, namely immunofluorescence (IF) and proximity ligation assay (PLA), and in vitro biophysical techniques, namely fluorescence, far-ultraviolet (far-UV) circular dichroism (CD), and isothermal titration calorimetry (ITC). We also characterized the binding of the two proteins by using in silico experiments. Our results showed that there was binding in tumor and non-tumoral cell lines. Binding in vitro between the two proteins was also monitored and found to occur with a dissociation constant in the low micromolar range (~10 µM). Finally, in silico experiments provided additional information on the possible structure of the binding complex, especially on the binding ARM-PKP1 hot-spot. Our findings suggest that RYBP might be a rescuer of the high expression of PKP1 in tumors, where it could decrease the epithelial-mesenchymal transition in some cancer cells.
Assuntos
Proteínas Intrinsicamente Desordenadas , Placofilinas , Ligação Proteica , Proteínas Repressoras , Humanos , Proteínas do Domínio Armadillo/metabolismo , Proteínas do Domínio Armadillo/química , Proteínas do Domínio Armadillo/genética , Dicroísmo Circular , Proteínas Intrinsicamente Desordenadas/metabolismo , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/genética , Placofilinas/metabolismo , Placofilinas/genética , Placofilinas/química , Domínios Proteicos , Proteínas Repressoras/metabolismo , Proteínas Repressoras/química , Proteínas Repressoras/genéticaRESUMO
RYBP (Ring1 and YY 1 binding protein) is a multifunctional, intrinsically disordered protein (IDP), best described as a transcriptional regulator. It exhibits a ubiquitin-binding functionality, binds to other transcription factors, and has a key role during embryonic development. RYBP, which folds upon binding to DNA, has a Zn-finger domain at its N-terminal region. By contrast, PADI4 is a well-folded protein and it is one the human isoforms of a family of enzymes implicated in the conversion of arginine to citrulline. As both proteins intervene in signaling pathways related to cancer development and are found in the same localizations within the cell, we hypothesized they may interact. We observed their association in the nucleus and cytosol in several cancer cell lines, by using immunofluorescence (IF) and proximity ligation assays (PLAs). Binding also occurred in vitro, as measured by isothermal titration calorimetry (ITC) and fluorescence, with a low micromolar affinity (~1 µM). AlphaFold2-multimer (AF2) results indicate that PADI4's catalytic domain interacts with the Arg53 of RYBP docking into its active site. As RYBP sensitizes cells to PARP (Poly (ADP-ribose) polymerase) inhibitors, we applied them in combination with an enzymatic inhibitor of PADI4 observing a change in cell proliferation, and the hampering of the interaction of both proteins. This study unveils for the first time the possible citrullination of an IDP, and suggests that this new interaction, whether it involves or not citrullination of RYBP, might have implications in cancer development and progression.
Assuntos
Neoplasias , Fatores de Transcrição , Humanos , Fatores de Transcrição/genética , Linhagem Celular , Neoplasias/genética , Epigênese Genética , Proteínas Repressoras/genéticaRESUMO
In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI(3)), it was possible to form covalent bonds between the Ga(3+) ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy.
RESUMO
Neste artigo abordaremos a problemática dos idosos em uma sociedade na qual é cada vez maior o número de pessoas com idade superior a 65 anos. Uma das conseqüências do aumento da média de idade e de uma maior qualidade de vida dos idosos é, precisamente, a não existência de pessoas que os assumam. Estudaremos, nestas linhas, o risco de abandono e quais são as variáveis mais importantes na predição deste risco. Para tanto trabalharemos com dois grupos de idosos (os que vivem em casa com seus familiares e os que vivem em residências para idosos), o que totaliza 121 idosos e, mediante a técnica estatística da regressão logística obteremos as variáveis com maior peso para discriminar entre os dois grupos e predizer o risco de abandono (AU)
RESUMO
El objetivo de este estudio fue evaluar la eficacia y seguridad de la nimodipina en pacientes con demencia degenerativa primaria tipo Alzheimer (PDD-AD) y demencia vascular debido a infartos múltiples (MID). Este fue el primer estudio abierto latinoamericano, multinacional multicéntrico, con un período de duración de 12 semanas. El seguimiento incluyó una evaluación basal y luego cada cuatro semanas, con una serie de pruebas tanto cognitivas (Mini Mental State Examination (MMSE) y Trail Marking Test (TMT-A), como escalas de comportamiento y funcionalidad (Sandoz Clinical Assesment Geriatric Scale (SSCAG) y Assessment of Geriatric Symtoms (RAGS-E)