Mechanisms for the Evolution of a Derived Function in the Ancestral Glucocorticoid Receptor

Understanding the genetic, structural, and biophysical mechanisms that caused protein functions to evolve is a central goal of molecular evolutionary studies. Ancestral sequence reconstruction (ASR) offers an experimental approach to these questions. Here we use ASR to shed light on the earliest functions and evolution of the glucocorticoid receptor (GR), a steroid-activated transcription factor that plays a key role in the regulation of vertebrate physiology. Prior work showed that GR and its paralog, the mineralocorticoid receptor (MR), duplicated from a common ancestor roughly 450 million years ago; the ancestral functions were largely conserved in the MR lineage, but the functions of GRs—reduced sensitivity to all hormones and increased selectivity for glucocorticoids—are derived. Although the mechanisms for the evolution of glucocorticoid specificity have been identified, how reduced sensitivity evolved has not yet been studied. Here we report on the reconstruction of the deepest ancestor in the GR lineage (AncGR1) and demonstrate that GR's reduced sensitivity evolved before the acquisition of restricted hormone specificity, shortly after the GR–MR split. Using site-directed mutagenesis, X-ray crystallography, and computational analyses of protein stability to recapitulate and determine the effects of historical mutations, we show that AncGR1's reduced ligand sensitivity evolved primarily due to three key substitutions. Two large-effect mutations weakened hydrogen bonds and van der Waals interactions within the ancestral protein, reducing its stability. The degenerative effect of these two mutations is extremely strong, but a third permissive substitution, which has no apparent effect on function in the ancestral background and is likely to have occurred first, buffered the effects of the destabilizing mutations. Taken together, our results highlight the potentially creative role of substitutions that partially degrade protein structure and function and reinforce the importance of permissive mutations in protein evolution

Gene expression variability across cells and species shapes innate immunity.

As the first line of defence against pathogens, cells mount an innate immune response, which varies widely from cell to cell. The response must be potent but carefully controlled to avoid self-damage. How these constraints have shaped the evolution of innate immunity remains poorly understood. Here we characterize the innate immune response's transcriptional divergence between species and variability in expression among cells. Using bulk and single-cell transcriptomics in fibroblasts and mononuclear phagocytes from different species, challenged with immune stimuli, we map the architecture of the innate immune response. Transcriptionally diverging genes, including those that encode cytokines and chemokines, vary across cells and have distinct promoter structures. Conversely, genes that are involved in the regulation of this response, such as those that encode transcription factors and kinases, are conserved between species and display low cell-to-cell variability in expression. We suggest that this expression pattern, which is observed across species and conditions, has evolved as a mechanism for fine-tuned regulation to achieve an effective but balanced response

Cuidado ecológico: o significado para profissionais de um hospital geral Cuidado ecológico: el significado para profesionales de un hospital general Ecological care: meaning for health care professionals from a general hospital

OBJETIVO: Compreender à luz do pensamento complexo, o significado do cuidado ecológico e como este vem sendo associado à prática de profissionais que trabalham em um hospital geral. MÉTODOS: Estudo descritivo de natureza qualitativa realizado com 15 profissionais que atuam em três diferentes setores: Serviço de Lavanderia, Serviço de Nutrição e uma Unidade de Internação. Os dados foram coletados por meio de um questionário semi-estruturado e submetidos à análise de conteúdo proposta por Bardin. RESULTADOS: As categorias encontradas foram: Significando o cuidado ecológico, Salientando a importância do cuidado ecológico para a prática profissional e Medidas preventivas em saúde associadas ao cuidado ecológico. CONCLUSÕES: O estudo evidenciou que existe uma preocupação geral, ainda que incipiente, a respeito da problemática ambiental. A preocupação principal está relacionada à separação, reciclagem e destino adequado do lixo, mesmo que alguns profissionais tenham sinalizado para a importância de medidas preventivas como a lavagem das mãos, utilização de produtos biodegradáveis, entre outros.<br>OBJETIVO: Comprender a La luz del pensamiento complejo, el significado del cuidado ecológico y cómo éste viene siendo asociado a la práctica de profesionales que trabajan en un hospital general. MÉTODOS: Estudio descriptivo de naturaleza cualitativa realizado con 15 profesionales que actúan en tres diferentes sectores: Servicio de Lavandería, Servicio de Nutrición y una Unidad de Internamiento. Los datos fueron recolectados por medio de un cuestionario semi-estructurado y sometidos al análisis de contenido propuesto por Bardin. RESULTADOS: Las categorías encontradas fueron: Significando el cuidado ecológico, resaltando la importancia del cuidado ecológico para la práctica profesional y Medidas preventivas en salud asociadas al cuidado ecológico. CONCLUSIONES: El estudio evidenció que existe una preocupación general, todavía incipiente, respecto a la problemática ambiental. La preocupación principal está relacionada a la separación, reciclaje y destino adecuado de la basura, aunque algunos profesionales hayan destacado la importancia de medidas preventivas como el lavado de las manos, utilización de productos biodegradables, entre otros.<br>OBJECTIVE: To understand the meaning of ecological care in view of complex thinking and how ecological care had been associated with the clinical practice of health care professionals from a general hospital. METHODS: This was a qualitative descriptive study among 15 health care professionals working in the laundry, nutrition, or inpatient unit. A semi-structured questionnaire was used to collect the data. Bardin's recommendations guided the content analysis. RESULTS: The following categories emerged: Meaning of ecological care, significance of ecological care for clinical practice, and preventive measures associated with ecological care. CONCLUSIONS: Although incipient, the findings suggest that there is a general concern regarding environmental issues. Even though some health care professionals stated the significance of hand washing and use of biodegradable products as preventive measures, the main concern was related to the separation, recycling, and disposal of trash