A functional portrait of Med7 and the mediator complex in Candida albicans.

Mediator is a multi-subunit protein complex that regulates gene expression in eukaryotes by integrating physiological and developmental signals and transmitting them to the general RNA polymerase II machinery. We examined, in the fungal pathogen Candida albicans, a set of conditional alleles of genes encoding Mediator subunits of the head, middle, and tail modules that were found to be essential in the related ascomycete Saccharomyces cerevisiae. Intriguingly, while the Med4, 8, 10, 11, 14, 17, 21 and 22 subunits were essential in both fungi, the structurally highly conserved Med7 subunit was apparently non-essential in C. albicans. While loss of CaMed7 did not lead to loss of viability under normal growth conditions, it dramatically influenced the pathogen's ability to grow in different carbon sources, to form hyphae and biofilms, and to colonize the gastrointestinal tracts of mice. We used epitope tagging and location profiling of the Med7 subunit to examine the distribution of the DNA sites bound by Mediator during growth in either the yeast or the hyphal form, two distinct morphologies characterized by different transcription profiles. We observed a core set of 200 genes bound by Med7 under both conditions; this core set is expanded moderately during yeast growth, but is expanded considerably during hyphal growth, supporting the idea that Mediator binding correlates with changes in transcriptional activity and that this binding is condition specific. Med7 bound not only in the promoter regions of active genes but also within coding regions and at the 3' ends of genes. By combining genome-wide location profiling, expression analyses and phenotyping, we have identified different Med7p-influenced regulons including genes related to glycolysis and the Filamentous Growth Regulator family. In the absence of Med7, the ribosomal regulon is de-repressed, suggesting Med7 is involved in central aspects of growth control.

Medical Nutrition Education for Health, Not Harm: BMI, Weight Stigma, Eating Disorders, and Social Determinants of Health.

Effective nutrition training is fundamental to medical education. Current training is inadequate and can cause harm to students and patients alike; it leaves physicians unprepared to counsel on nutrition, places undue focus on weight and body mass index (BMI), can exacerbate anti-obesity bias, and increase risk for development of eating disorders, while neglecting social determinants of health and communication skills. Physicians and educators hold positions of influence in society; what we say and how we say it matters. We propose actionable approaches to improve nutrition education to minimize harm and pursue evidence-based, effective, and equitable healthcare.

The transcription factor REST is lost in aggressive breast cancer.

The function of the tumor suppressor RE1 silencing transcription factor (REST) is lost in colon and small cell lung cancers and is known to induce anchorage-independent growth in human mammary epithelial cells. However, nothing is currently known about the role of this tumor suppressor in breast cancer. Here, we test the hypothesis that loss of REST function plays a role in breast cancer. To assay breast tumors for REST function, we developed a 24-gene signature composed of direct targets of the transcriptional repressor. Using the 24- gene signature, we identified a previously undefined RESTless breast tumor subtype. Using gene set enrichment analysis, we confirmed the aberrant expression of REST target genes in the REST-less tumors, including neuronal gene targets of REST that are normally not expressed outside the nervous system. Examination of REST mRNA identified a truncated splice variant of REST present in the REST-less tumor population, but not other tumors. Histological analysis of 182 outcome-associated breast tumor tissues also identified a subpopulation of tumors that lack full-length, functional REST and over-express the neuroendocrine marker and REST target gene Chromogranin A. Importantly, patients whose tumors were found to be REST-less using either the 24-gene signature or histology had significantly poorer prognosis and were more than twice as likely to undergo disease recurrence within the first 3 years after diagnosis. We show here that REST function is lost in breast cancer, at least in part via an alternative splicing mechanism. Patients with REST-less breast cancer undergo significantly more early disease recurrence than those with fully functional REST, regardless of estrogen receptor or HER2 status. Importantly, REST status may serve as a predictor of poor prognosis, helping to untangle the heterogeneity inherent in disease course and response to treatment. Additionally, the alternative splicing observed in REST-less breast cancer is an attractive therapeutic target.

Dietary Supplementation With Medium-Chain Triglycerides Reduces Candida Gastrointestinal Colonization in Preterm Infants.

BACKGROUND: Candida is an important cause of infections in premature infants. Gastrointestinal colonization with Candida is a common site of entry for disseminated disease. The objective of this study was to determine whether a dietary supplement of medium-chain triglycerides (MCTs) reduces Candida colonization in preterm infants. METHODS: Preterm infants with Candida colonization (n = 12) receiving enteral feedings of either infant formula (n = 5) or breast milk (n = 7) were randomized to MCT supplementation (n = 8) or no supplementation (n = 4). Daily stool samples were collected to determine fungal burden during a 3-week study period. Infants in the MCT group received supplementation during 1 week of the study period. The primary outcome was fungal burden during the supplementation period as compared with the periods before and after supplementation. RESULTS: Supplementation of MCT led to a marked increase in MCT intake relative to unsupplemented breast milk or formula as measured by capric acid content. In the treatment group, there was a significant reduction in fungal burden during the supplementation period as compared with the period before supplementation (rate ratio, 0.15; P = 0.02), with a significant increase after supplementation was stopped (rate ratio, 61; P < 0.001). Fungal burden in the control group did not show similar changes. CONCLUSIONS: Dietary supplementation with MCT may be an effective method to reduce Candida colonization in preterm infants.

Transcriptional Profiling of Candida albicans in the Host.

Gene expression profiling has become an important tool for determining gene functions, performing phenotypic analysis, and quantifying the differential expression of individual transcripts under various conditions. Candida albicans gene expression is highly responsive to environmental conditions and rapidly adapts to various niches within the host. Here, we describe a mouse model of gastrointestinal colonization with C. albicans, the measurement of colonization in fecal pellets, and the collection of samples for transcriptional profiling. We describe how to extract and purify RNA suitable for analysis via RT-qPCR or microarray.

Manipulation of Host Diet To Reduce Gastrointestinal Colonization by the Opportunistic Pathogen Candida albicans.

Candida albicans, the most common human fungal pathogen, can cause systemic infections with a mortality rate of ~40%. Infections arise from colonization of the gastrointestinal (GI) tract, where C. albicans is part of the normal microflora. Reducing colonization in at-risk patients using antifungal drugs prevents C. albicans-associated mortalities. C. albicans provides a clinically relevant system for studying the relationship between diet and the microbiota as it relates to commensalism and pathogenicity. As a first step toward a dietary intervention to reduce C. albicans GI colonization, we investigated the impact of dietary lipids on murine colonization by C. albicans. Coconut oil and its constituent fatty acids have antifungal activity in vitro; we hypothesized that dietary coconut oil would reduce GI colonization by C. albicans. Colonization was lower in mice fed a coconut oil-rich diet than in mice fed diets rich in beef tallow or soybean oil. Switching beef tallow-fed mice to a coconut oil diet reduced preexisting colonization. Coconut oil reduced colonization even when the diet also contained beef tallow. Dietary coconut oil also altered the metabolic program of colonizing C. albicans cells. Long-chain fatty acids were less abundant in the cecal contents of coconut oil-fed mice than in the cecal contents of beef tallow-fed mice; the expression of genes involved in fatty acid utilization was lower in C. albicans from coconut oil-fed mice than in C. albicans from beef tallow-fed mice. Extrapolating to humans, these findings suggest that coconut oil could become the first dietary intervention to reduce C. albicans GI colonization. IMPORTANCE Candida albicans, the most common human fungal pathogen, can cause infections with a mortality rate of ~40%. C. albicans is part of the normal gut flora, but when a patient's immune system is compromised, it can leave the gut and cause infections. By reducing the amount of C. albicans in the gut of susceptible patients, infections (and the resulting fatalities) can be prevented. Currently, this is done using antimicrobial drugs; to "preserve" drugs for treating infections, we looked for a dietary change to reduce the amount of C. albicans in the gut. Using a mouse model, we showed that adding coconut oil to the diet could become the first drug-free way to reduce C. albicans in the gut. More broadly, this model lets us study the interactions between our diet and the microbes in our body and the reasons why some of those microbes, under certain conditions, cause disease. Podcast: A podcast concerning this article is available.

Shaping the Future of Research: a perspective from junior scientists.

The landscape of scientific research and funding is in flux as a result of tight budgets, evolving models of both publishing and evaluation, and questions about training and workforce stability. As future leaders, junior scientists are uniquely poised to shape the culture and practice of science in response to these challenges. A group of postdocs in the Boston area who are invested in improving the scientific endeavor, planned a symposium held on October 2 (nd) and 3 (rd), 2014, as a way to join the discussion about the future of US biomedical research. Here we present a report of the proceedings of participant-driven workshops and the organizers' synthesis of the outcomes.

Induction of the RNA regulator LIN28A is required for the growth and pathogenesis of RESTless breast tumors.

The transcription factor RE1 silencing transcription factor (REST) is lost in approximately 20% of breast cancers. Although it is known that these RESTless tumors are highly aggressive and include all tumor subtypes, the underlying tumorigenic mechanisms remain unknown. In this study, we show that loss of REST results in upregulation of LIN28A, a known promoter of tumor development, in breast cancer cell lines and human breast tumors. We found that LIN28A was a direct transcriptional target of REST in cancer cells and that loss of REST resulted in increased LIN28A expression and enhanced tumor growth both in vitro and in vivo, effects that were dependent on heightened LIN28A expression. Tumors lacking REST expression were locally invasive, consistent with the increased lymph node involvement observed in human RESTless tumors. Clinically, human RESTless breast tumors also displayed significantly enhanced LIN28A expression when compared with non-RESTless tumors. Our findings therefore show a critical role for the REST-LIN28A axis in tumor aggression and suggest a causative relationship between REST loss and tumorigenicity in vivo.