Caveolin-1 suppresses tumor formation through the inhibition of the unfolded protein response.

Caveolin-1 (CAV1), is a broadly expressed, membrane-associated scaffolding protein that acts both, as a tumor suppressor and a promoter of metastasis, depending on the type of cancer and stage. CAV1 is downregulated in human tumors, tumor cell lines and oncogene-transformed cells. The tumor suppressor activity of CAV1 is generally associated with its presence at the plasma membrane, where it participates, together with cavins, in the formation of caveolae and also has been suggested to interact with and inhibit a wide variety of proteins through interactions mediated by the scaffolding domain. However, a pool of CAV1 is also located at the endoplasmic reticulum (ER), modulating the secretory pathway in a manner dependent on serine-80 (S80) phosphorylation. In melanoma cells, CAV1 expression suppresses tumor formation, but the protein is largely absent from the plasma membrane and does not form caveolae. Perturbations to the function of the ER are emerging as a central driver of cancer, highlighting the activation of the unfolded protein response (UPR), a central pathway involved in stress mitigation. Here we provide evidence indicating that the expression of CAV1 represses the activation of the UPR in vitro and in solid tumors, reflected in the attenuation of PERK and IRE1α signaling. These effects correlated with increased susceptibility of cells to ER stress and hypoxia. Interestingly, the tumor suppressor activity of CAV1 was abrogated by site-directed mutagenesis of S80, correlating with a reduced ability to repress the UPR. We conclude that the tumor suppression by CAV1 involves the attenuation of the UPR, and identified S80 as essential in this context. This suggests that intracellular CAV1 regulates cancer through alternative signaling outputs.

Sources of bias in genetic association studies in cattle: A review / Fuentes de sesgo en estudios de asociación genética en ganado bovino: Revisión de literatura / Fontes de viés nos estudos de associação genética em bovinos: Revisão da literatura

Abstract Background: Genetic association studies have been increasingly used in cattle breeding programs. However, inconsistent results -such as positive, negative, or absence of association- across studies restrain reproducibility and proper implementation, propitiating the occurrence of bias. Objective: To identify and classify potential sources of bias and determine possible strategies to avoid it in genetic association studies in cattle. Source of bias in genetic association studies: Genetic and genomic sources of bias include effects associated with the gene loci governing expression. Sampling-related and statistical biases are related with factors such as stratification and database size. Strategies to correct bias in genetic association studies: Correction strategies differ in nature. Genetic and genomic strategies are based on determining the appropriate approach to obtain and report the genetic information. Sampling-related and statistical strategies are based on grouping individuals with certain traits that lead to a reduction in heterogeneity. Conclusion: It is necessary to consider the methodology used in previous studies to establish a hierarchy of sources of bias and facilitate decisions on the use of tools to reduce inconsistencies in the results of future studies.

Resumen Antecedentes: Los estudios de asociación genética son cada vez más usados en los programas de mejoramiento genético. Sin embargo, resultados inconsistentes de los estudios -como positivos, negativos o ausencia de asociación- restringen la reproducibilidad y su aplicación adecuada, propiciando la aparición de sesgos. Objetivo: Identificar y clasificar las fuentes potenciales de sesgo y determinar posibles estrategias para evitarlo en estudios de asociación genética en ganado. Fuentes de sesgo en estudios de asociación genética: Las fuentes genéticas y genómicas de sesgo incluyen los efectos asociados con la expresión que gobierna los loci. Los sesgos estadísticos y de muestreo están relacionados con factores como la estratificación y el tamaño de la base de datos. Estrategias para corregir sesgos en estudios de asociación genética: Las estrategias de corrección difieren en naturaleza. Las estrategias genéticas y genómicas se basan en determinar el enfoque apropiado para obtener la información genética. Las estrategias estadísticas y relacionadas con el muestreo se basan en la agrupación de individuos con ciertos rasgos que conducen a una reducción de la heterogeneidad. Conclusión. Se deben considerar las metodologías utilizadas en estudios previos para jerarquizar las fuentes de sesgo y facilitar las decisiones sobre el uso de herramientas para reducir inconsistencias en resultados futuros.

Resumo Antecedentes: Nos programas de criação de bovinos, os estudos de associação genética têm sido cada vez mais utilizados. No entanto, resultados inconsistentes, como positivos, negativos ou ausência de associação entre os estudos, restringem a reprodutibilidade e sua adequada implementação, propiciando o aparecimento de viés. Objetivo: Identificar e classificar potenciais fontes de viés e determinar estratégias possíveis para evitá-lo nos estudos de associação genética em bovinos. Fonte de viés em estudos de associação genética: Fontes genéticas e genômicas do viés incluem os efeitos associados aos genes que relacionam a expressão. Os vícios estatísticos e de amostragem estão relacionados a fatores como a estratificação e o tamanho do banco de dados. Estratégias para corrigir os viéses nos estudos de associação genética: As estratégias de correção diferem na natureza. As estratégias genéticas e genômicas são baseadas na determinação da abordagem apropriada para obter e relatar a informação genética. As estratégias estatísticas e de amostragem baseiam-se no agrupamento de indivíduos com certos traços que levam a uma redução na heterogeneidade. Conclusão: É necessário considerar a metodologia utilizada em estudos anteriores para estabelecer uma hierarquia de fontes de viés e facilitar decisões sobre o uso de ferramentas para reduzir inconsistências nos resultados de estudos futuros.

Cloning and molecular characterization of two ferritins from red abalone Haliotis rufescens and their expressions in response to bacterial challenge at juvenile and adult life stages.

Ferritins are ubiquitous proteins with a pivotal role in iron storage and homeostasis, and in host defense responses during infection by pathogens in several organisms, including mollusks. In this study, we characterized two ferritin homologues in the red abalone Haliotis rufescens, a species of economic importance for Chile, USA and Mexico. Two ferritin subunits (Hrfer1 and Hrfer2) were cloned. Hrfer1 cDNA is an 807 bp clone containing a 516 bp open reading frame (ORF) that corresponds to a novel ferritin subunit in H. rufescens. Hrfer2 cDNA is an 868 bp clone containing a 516 bp ORF that corresponds to a previously reported ferritin subunit, but in this study 5'- and 3'-UTR sequences were additionally found. We detected a putative Iron Responsive Element (IRE) in the 5'-UTR sequence, suggesting a posttranscriptional regulation of Hrfer2 translation by iron. The deduced protein sequences of both cDNAs possessed the motifs and domains required in functional ferritin subunits. Expression patterns of both ferritins in different tissues, during different developmental stages, and in response to bacterial (Vibrio splendidus) exposure were examined. Both Hrfer1 and Hrfer2 are most expressed in digestive gland and gonad. Hrfer1 mRNA levels increased about 34-fold along with larval developmental process, attaining the highest level in the creeping post-larvae. Exogenous feeding is initiated at the creeping larva stage; thus, the increase of Hrfer1 may suggest and immunity-related role upon exposure to bacteria. Highest Hrfer2 expression levels were detected at trochophore stage; which may be related with early shell formation. Upon challenge with, the bacteria an early mild induction of Hrfer2 (2 h post-challenge), followed by a stronger induction of Hrfer1 at 15 h post-challenge, was observed in haemocytes from adult abalones. While maximal upregulation of both genes in the whole individual occurred at 24 h post-challenge, in juveniles. A significant increase in ferritin protein levels from 6 h to 24 h post-challenge was also detected. Our results suggest an involvement of Hrfer1 and Hrfer2, and of ferritin proteins in the immune response of H. rufescens to bacterial infection.

Genetic and mechanistic diversity in pediatric hemophagocytic lymphohistiocytosis.

The HLH-2004 criteria are used to diagnose hemophagocytic lymphohistiocytosis (HLH), yet concern exists for their misapplication, resulting in suboptimal treatment of some patients. We sought to define the genomic spectrum and associated outcomes of a diverse cohort of children who met the HLH-2004 criteria. Genetic testing was performed clinically or through research-based whole-exome sequencing. Clinical metrics were analyzed with respect to genomic results. Of 122 subjects enrolled over the course of 17 years, 101 subjects received genetic testing. Biallelic familial HLH (fHLH) gene defects were identified in only 19 (19%) and correlated with presentation at younger than 1 year of age (P < .0001). Digenic fHLH variants were observed but lacked statistical support for disease association. In 28 (58%) of 48 subjects, research whole-exome sequencing analyses successfully identified likely molecular explanations, including underlying primary immunodeficiency diseases, dysregulated immune activation and proliferation disorders, and potentially novel genetic conditions. Two-thirds of patients identified by the HLH-2004 criteria had underlying etiologies for HLH, including genetic defects, autoimmunity, and malignancy. Overall survival was 45%, and increased mortality correlated with HLH triggered by infection or malignancy (P < .05). Differences in survival did not correlate with genetic profile or extent of therapy. HLH should be conceptualized as a phenotype of critical illness characterized by toxic activation of immune cells from different underlying mechanisms. In most patients with HLH, targeted sequencing of fHLH genes remains insufficient for identifying pathogenic mechanisms. Whole-exome sequencing, however, may identify specific therapeutic opportunities and affect hematopoietic stem cell transplantation options for these patients.

Molecular characterization of two ferritins of the scallop Argopecten purpuratus and gene expressions in association with early development, immune response and growth rate.

Ferritin is involved in several iron homoeostasis processes in molluscs. We characterized two ferritin homologues and their expression patterns in association with early development, growth rate and immune response in the scallop Argopecten purpuratus, a species of economic importance for Chile and Peru. Two ferritin subunits (Apfer1 and Apfer2) were cloned. Apfer1 cDNA is a 792bp clone containing a 516bp open reading frame (ORF) that corresponds to a novel ferritin subunit in A. purpuratus. Apfer2 cDNA is a 681bp clone containing a 522bp ORF that corresponds to a previously sequenced EST. A putative iron responsive element (IRE) was identified in the 5'-untranslated region of both genes. The deduced protein sequences of both cDNAs possessed the motifs and domains characteristic of functional ferritin subunits. Both genes showed differential expression patterns at tissue-specific and early development stage levels. Apfer1 expression level increased 40-fold along larval developmental stages, decreasing markedly after larval settlement. Apfer1 expression in mantle tissue was 2.8-fold higher in fast-growing than in slow-growing scallops. Apfer1 increased 8-fold in haemocytes 24h post-challenge with the bacterium Vibrio splendidus. Apfer2 expression did not differ between fast- and slow-growing scallops or in response to bacterial challenge. These results suggest that Apfer1 and Apfer2 may be involved in iron storage, larval development and shell formation. Apfer1 expression may additionally be involved in immune response against bacterial infections and also in growth; and thus would be a potential marker for immune capacity and for fast growth in A. purpuratus.

Caveolin-1-enhanced motility and focal adhesion turnover require tyrosine-14 but not accumulation to the rear in metastatic cancer cells.

Caveolin-1 is known to promote cell migration, and increased caveolin-1 expression is associated with tumor progression and metastasis. In fibroblasts, caveolin-1 polarization and phosphorylation of tyrosine-14 are essential to promote migration. However, the role of caveolin-1 in migration of metastatic cells remains poorly defined. Here, caveolin-1 participation in metastatic cell migration was evaluated by shRNA targeting of endogenous caveolin-1 in MDA-MB-231 human breast cancer cells and ectopic expression in B16-F10 mouse melanoma cells. Depletion of caveolin-1 in MDA-MB-231 cells reduced, while expression in B16-F10 cells promoted migration, polarization and focal adhesion turnover in a sequence of events that involved phosphorylation of tyrosine-14 and Rac-1 activation. In B16-F10 cells, expression of a non-phosphorylatable tyrosine-14 to phenylalanine mutant failed to recapitulate the effects observed with wild-type caveolin-1. Alternatively, treatment of MDA-MB-231 cells with the Src family kinase inhibitor PP2 reduced caveolin-1 phosphorylation on tyrosine-14 and cell migration. Surprisingly, unlike for fibroblasts, caveolin-1 polarization and re-localization to the trailing edge were not observed in migrating metastatic cells. Thus, expression and phosphorylation, but not polarization of caveolin-1 favor the highly mobile phenotype of metastatic cells.