RESUMO
CDK6 kinase regulates cell-cycle progression in G1, together with CDK4, but has cell-, tissue- and developmentally distinct functions associated with transcription, angiogenesis and metabolism. Although CDK6 makes an attractive cancer biomarker and target, there are no means of assessing its activity in a complex environment. In this study, we describe the design, engineering and characterisation of a fluorescent peptide biosensor derived from 6-phosphofructokinase that reports on CDK6 kinase activity through sensitive changes in fluorescence intensity. This biosensor can report on CDK6 activity in a dose-dependent fashion, thereby enabling quantification of differences in kinase activity in complex and physiologically relevant environments. Further implementation of this biosensor in different lung and melanoma cell lines, as well as in mesothelioma cell lines derived from patients together with a CDK4 biosensor highlighted differences in kinase activity between CDK6 and CDK4 kinase. This work demonstrates the utility of these selective tools for monitoring two closely related kinases comparatively and simultaneously in the same samples, thereby offering attractive perspectives for diagnostic and therapeutic purposes.
Assuntos
Técnicas Biossensoriais/métodos , Quinase 6 Dependente de Ciclina/metabolismo , Corantes Fluorescentes/química , Peptídeos/metabolismo , Sequência de Aminoácidos , Extratos Celulares/química , Linhagem Celular Tumoral , Quinase 4 Dependente de Ciclina/genética , Quinase 4 Dependente de Ciclina/metabolismo , Quinase 6 Dependente de Ciclina/genética , Humanos , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Mesotelioma/metabolismo , Mesotelioma/patologia , Peptídeos/química , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Rodaminas/química , Espectrometria de FluorescênciaRESUMO
Resistance to thyroid hormone alpha (RTHα) is a rare and under-recognized genetic disease caused by mutations of THRA, the gene encoding thyroid hormone receptor α1 (TRα1). We report here two novel THRA missense mutations (M259T, T273A) in patients with RTHα. We combined biochemical and cellular assays with in silico modeling to assess the capacity of mutant TRα1 to bind triiodothyronine (T3), to heterodimerize with RXR, to interact with transcriptional coregulators, and to transduce a T3 transcriptional response. M259T, and to a lower extent T273A, reduces the affinity of TRα1 for T3. Their negative influence is only reverted by large excess of T3. The severity of the two novel RTHα cases originates from a reduction in the binding affinity of TRα1 mutants to T3 and thus correlates with the incapacity of corepressors to dissociate from TRα1 mutants in the presence of T3.