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NIH Awards Four Grants for microRNA Research in February

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The National Institutes of Health this month awarded four grants to help pay for microRNA-related research projects aiming to study the function of conserved miRNAs in plants, the role the non-coding RNAs play in human T- and B-cell activation, the impact of miRNAs in brain cancer, and how miRNAs affect the aging process.

The first grant, worth $223,430 in the first year of its four-year term, was awarded to Pennsylvania State University's Michael Axtell to support his investigation into the functional and evolutionary genomics of ancient miRNAs.

"A core set of [conserved] plant microRNAs regulate homologous targets in very different plant species … [and] these ancient microRNA-target interactions are thought to regulate development processes," he wrote in the grant's abstract.

But questions linger as to how the same miRNA-target interactions "guide the very different developmental patterns and morphologies of highly divergent plants," he noted. "Do they ultimately control ancient, conserved suites of gene expression, or have they been differentially utilized in different lineages? This project seeks to answer these questions by using molecular genetics to elucidate the functions and regulatory networks of ancient miRNAs in two very different land plants."

Specifically, Axtell aims to "genetically dissect" the function of the miRNA machinery in the moss Physcomitrella patens, according to the abstract. Then, he plans to analyze the functions of homologous ancient miRNA-target interactions in P. patens and Arabidopsis thaliana, and "empirically determine and compare" the gene-regulatory networks controlled by ancient miRNA-target interactions in the two plant species.

The second grant was awarded to Scripps Research Institute researcher Daniel Salomon to help fund a five-year investigation into how miRNAs contribute to the regulation of human lymphocyte activation.

"Current literature identifies 30 miRNAs associated with hematopoietic lineage cells but only a small subset [are] documented in T and B cells," Salomon wrote in the grant's abstract. "We hypothesize that miRNAs play a pivotal role in [regulating] human immunity by targeting key differentially and constitutively expressed genes regulating T and B lymphocyte activation, differentiation, and survival."

The goal of Salomon's NIH-funded project, which is worth $474,750 in its first year, is to conduct a full analysis of miRNA expression in human T- and B-cell activation, and to investigate the possibility that post-transcriptional processing of miRNA precursors in the nucleus is important in this activation process.

Salomon also aims to use mass-spectrometry proteomics and deep-sequencing tools to "discover the correlations between protein, mRNA, and miRNA expression and molecular network regulation during activation, and to validate the number of high-value miRNA candidates in biologically significant pathways," according to the grant's abstract.

"If our multidimensional '-omics' approach is successful, then it is a proof of concept for an effort to organize the full force of a large collaborative group at validating all the major pathways for each cell type, identifying the impact of immunosuppression, correlate the results with clinical samples from transplant patients, and … [advancing] our understanding of transplant immunology," the abstract adds.

University of Virginia, Charlottesville, investigator Benjamin Purow was awarded the third grant, worth $315,120 in its first year, to help him determine whether miRNA inhibition of the Notch cell-signaling pathway can be used to treat brain cancer.

Preliminary studies indicate that two miRNAs, miR-7 and miR-326, have targets in the Notch pathway, suppress Notch activity, show decreased expression in human gliomas, and inhibit viability and invasiveness of glioma cells in vitro, according to the grant's abstract. As such, Purow and colleagues are undertaking a "systematic investigation" of the miRNAs as Notch-inhibiting tumor suppressors with therapeutic potential.

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As part of their four-year project, they will use immunoblotting and 3' UTR luciferase reporters to "validate which of the predicted Notch pathway members are … directly targeted by these microRNAs," Purow wrote in the abstract. "Additionally, we will determine whether inhibitors of the [miRNAs] can increase Notch activity and expression of Notch pathway targets."

The researchers also propose to use the grant funding to quantify the expression of the various forms of miR-7 and miR-326 in human glioma and normal brain tissue to see if their levels correlate to Notch activity and the expression of Notch pathway proteins. The phenotypic effects of transfecting the miRNAs into established glioma lines will then be evaluated.

"Recent evidence has suggested that standard cancer cell lines may be poorly representative of the original tumors … and that gliomas and other cancers may be more accurately modeled by lines grown from a small stem cell-like subpopulation within the tumors," Purow noted in the abstract. "It is [also] hypothesized that this stem cell-like fraction is responsible for tumorigenesis and regrowth of tumors, and they are highly resistant to standard therapies."

Therefore, the team also aims to determine the effects of the two miRNAs on the growth, differentiation, and invasiveness in glioma tumor stem cell lines in vitro and in orthotopic xenograft mouse models," the abstract states.

The final grant, which runs for five years, was awarded to Yale University's Frank Slack to fund his continued investigation into the role of miRNAs on the aging process. Financial data for the grant was not available.

"Genetic studies in C. elegans have identified myriad genes and pathways that affect longevity," Slack wrote in the grant's abstract. "However, the extent of miRNA involvement in aging, and the genetic circuitry and mechanisms by which these genes modulate aging, has not been elucidated. This proposal will test the hypotheses that miRNAs play a fundamental role in life span by acting in aging pathways, and that their expression patterns provide novel biomarkers of aging."

To do so, Slack and his colleagues will characterize the life spans of [C. elegans] mutants with loss of over-expression of aging-associated miRNA candidates, and then search for the targets of the non-coding RNAs, the abstract states. The investigators will then make green fluorescent protein fusions to the promoters of miRNAs altered in aging and "identify a few miRNAs whose expression at a particular times or in a particular tissue predicts future life span.

"Given the high conservation of miRNAs across species, it is likely that insights uncovered by this research will have high relevance towards our understanding of aging in higher organisms and may suggest new diagnostic and therapeutic avenues to treat diseases of aging," the abstract concludes.

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