Alexander K. Murashov - US grants

DESCRIPTION (provided by applicant): Recent observations have demonstrated that nanomaterials may be toxic to human tissue and cell cultures, resulting in oxidative stress, inflammatory cytokine production and cell death. While the ability of nano-scaled particulate matter is known to cause a range of problems in respiratory system, recent observations suggest that the nervous system may be vulnerable as well. In particular, it was shown that nanoparticles can penetrate the blood-brain barrier affecting brain signaling linked to Alzheimer's and Parkinson's diseases, and decrease in cognitive function. However, the mechanism of nanomaterials toxicity on the nervous system has been poorly investigated. A significant question remaining to be addressed is how nanoparticles trigger changes in the nerve cells, and what can be done to early detect these deffects. Recent evidence suggests that microRNAs (miRNAs), small non-coding RNAs that regulate gene expression, may be an important prognostic factor in neurodegeneration caused by environmental exposures. While dysregulation of miRNAs has been observed in toxicological and neurological conditions, no mechanistic studies have been done on the role of miRNAs in nanotoxicity. One category of nanomaterial includes carbon nanotubes (CNTs), which are allotropes of carbon with a cylindrical nanostructure. These cylindrical structures have novel properties that make them useful in many applications in nanotechnology, electronics, optics, as well as in medicine. Their final usage, however, may be limited by their potential toxicity. In the current application, we hypothesize that exposure to CNTs will cause dysregulation of miRNAs in neuronal cells and will negatively impact neuronal function. Therefore, the specific aims for the two-year period are: 1) Determine impact of "direct" CNTs exposure on neuronal cultures in vitro, and "indirect" impact on peripheral neuron regeneration following respiratory CNTs exposure in vivo. 2) Characterize miRNA expression signature in neuronal cells in response to "direct" and "indirect" CNTs exposures. 3) Investigate if miRNAs depletion will make neuron regeneration more vulnerable to CNTs exposures by deleting Dicer in vitro and in vivo. The experiments in this application address clinically important question of CNTs neurotoxicity. The proposed research will be essential to establish a foundation for developing miRNA- based methods for diagnosis, prognosis and treatment of CNTs-associated health risks. The long-term objectives of this investigation are to elucidate role of miRNAs in mechanisms underlying the neurotoxicity of CNTs, to provide research opportunities for undergraduate and graduate students, and to provide data on which to establish future R01 grant applications. PUBLIC HEALTH RELEVANCE: The experiments in this application address clinically important question of epigenetic mechanisms of nanoparticle neurotoxicity. The proposed research will advance our understanding of the role of the microRNA pathway in mediating effects of nanoparticles on the nervous system, and will help to establish a foundation for developing methods for diagnosis, prognosis and treatment of nanoparticle associated health problems.

Abstract The prevention of childhood obesity is a key global health priority as obesity is a major contributor to increased morbidity and mortality, and is exponentially increasing in prevalence world-wide. Family aggregation studies demonstrate that adiposity tends to run in families with the heritability estimates for obesity as high as >0.70. Intergenerational studies show that ancestral nutrition can perpetuate its influence into the first and second generation of offspring via alterations in father?s sperm microRNA (miRNA) content and global methylation of DNA. While the majority of studies on intergenerational inheritance have focused on changes in parental diet, several new lines of evidence indicate that physical activity is another critical epigenetic modifier. Our published and preliminary findings demonstrate that offspring from fathers exposed to a long-term preconception exercise develop a ?thrifty phenotype?. As a result, these offspring show higher metabolic efficiency and an increased risk for obesity on a high fat diet. The observed intergenerational transmission was associated with alterations in DNA methylation and miRNA content in paternal spermatozoa. Based on these data, we propose to test the hypothesis that paternal long-term exercise induces heritable modifications in the metabolic phenotype/mitochondrial efficiency of the offspring via the male germ line. We will further determine whether these heritable changes are linked to alterations in miRNA content and DNA methylation. The specific aims for this project are: 1) To determine the impact of paternal long-term exercise on female and male offspring metabolic phenotype, mitochondrial efficiency, and susceptibility to developing obesity and glucose/insulin intolerance; 2) To determine the paternal-lineage DNA methylation patterns associated with offspring metabolic efficiency by high-throughput reduced representation bisulfite sequencing (RRBS) on epididymal spermatozoa from F0-F2 generations; 3) To determine the paternal-lineage miRNA profile associated with offspring metabolic efficiency and susceptibility to high fat diets by genome-wide RNA- Sequencing (RNA-Seq) on epididymal spermatozoa from F0-F2 generations. Integrated analysis on genome- wide RRBS methylation data and RNA-Seq data will be performed to identify cooperative relationships between methylation, miRNAs and transcriptomic changes and to further delineate the epigenetic network associated with intergenerational transmission of the thrifty phenotype. This project is expected to significantly advance our understanding of the epigenetic origins of intergenerational programming underlying familial predisposition to obesity and related metabolic diseases as well as provide excellent research opportunities for undergraduate and graduate students.