The National Institutes of Health this month awarded more than $400,000 in grant funding to support three research projects examining microRNAs in breast cancer, leukemia, and depression.
The first grant went to Duke University's Laura Simone-Bisogno, who is studying the post-transcriptional effects of RNA-binding proteins (RBPs) and their interactions with miRNAs in driving breast cancer progression.
Sequence-specific RBPs are known to regulate subsets of functionally related mRNAs as RNA regulons to form ribonucleoprotein complexes, or RNPs, which are remodeled during activation of cells with small-molecule drugs, she noted in her grant's abstract.
One RBP in particular, human antigen R (HuR), has been shown to be dysregulated in cancer, stabilizing mRNA targets encoding known cell growth regulators and proto-oncogenes. Meanwhile, studies by other researchers have shown that HuR's targets vary between cancerous and normal cells and suggest that it stabilizes its mRNA targets by competing with endogenous miRNAs.
"It is therefore likely that HuR differentially regulates the stability of mRNAs encoding factors involved in tumorigenesis by repressing typically suppressive microRNAs, resulting in the coordinated synthesis of cancer-associated proteins and enhancement of disease progression," she noted in the abstract.
With the NIH funding, Simone-Bisogno and her colleagues aim to perform RNP immunoprecipitation followed by high-throughput sequencing to identify and map remodeling of mRNA subsets associated with HuR throughout a time course of human breast cancer malignancy, beginning with normal human mammary epithelial cells.
In parallel, similar experiments will be run to identify mRNA subsets associated with Argonaute2 to pinpoint those targeted by miRNAs during the time course. The mechanisms that allow HuR to rescue mRNA targets from miRNA inhibition will be studied using a range of techniques including luciferase constructs, knockout and rescue experiments, immunofluorescence, and RNA affinity precipitation assays.
In the end, Simone-Bisogno expects that her studies will yield post-transcriptional signatures that may be used to identify small-molecule inhibitors of HuR that can help "counter the regulator changes that contribute to advanced stages of malignancy."
The three-year project began on March 1 and is worth $33,028 in its first year.
The second grant was awarded to Arnav Mehta of the California Institute of Technology to fund his investigations into the link between miR-125b and myeloid leukemia.
In 2012, he and his colleagues reported on the discovery that overexpression of the miRNA is all that is required to trigger an aggressive form of the disease in mice, and that it regulates hematopoiesis by targeting Lin28A.
Additionally, miR-125b was found to directly target the tumor suppressor IRF4, which itself binds to an adaptor protein in the NF-kappa B signaling pathway to inhibit NF-kappa B activation. Dysregulation of NF-kappa B is linked to a variety of cancers, inflammatory conditions, and autoimmune diseases.
Hypothesizing that miR-125b influences myeloid leukemia development through its influence on NF-kappa B, Mehta aims to use the NIH funding to further characterize the miRNA's role in the cancer.
He and his colleagues also plan to investigate the contribution of IRF4 to this process, as well as how NF-kappa B signaling increases myeloid output and causes leukemia in conjunction with miR-125b overexpression.
The grant began on March 1 and runs for two years. It is worth $42,676 in the first year.
The last grant was awarded to University of Alabama at Birmingham researcher Yogesh Dwivedi, who is investigating the potential role of miRNAs in major depression.
He and his colleagues have published a number of reports recently that link miRNAs to various psychological states including schizophrenia, bipolar disorder, and learned helplessness. Meantime, work from others has shown the small, non-coding RNAs are involved in neural plasticity.
Based on these and other findings, he hypothesizes that that subsets of miRNAs and their variants are differentially coexpressed in the brains of people with major depressive disorder, affecting specific neural/synaptic mRNA and cellular pathways that contribute to the condition.
With the NIH award, he and his team will profile miRNA expression by small RNA sequencing in post-mortem brain samples to identify novel miRNAs and analyze differentially expressed miRNAs, according to his grant's abstract. They also aim to identify regulatory relationships between mRNA and miRNA by mapping co-expression network modules and to analyze miRNA-mRNA pairs. Altered miRNAs and their specific target genes will be validated experimentally, with changes examined at the cellular level.
They also plan on examining the effect synaptic miRNAs have on major depression pathogenesis by determining miRNA enrichment via small RNA sequencing in synaptosomes, analyzing target genes and co-expression modules of miRNA-mRNA specifically altered in the synaptic fraction, and examining pri-/pre-miRNAs and components of miRNA biogenesis machinery at synaptic level.
He expects this work to provide a foundation for the development of miRNA-based molecular tools that will assist in the creation of depression treatments.
The grant runs from March 5 until Jan. 31, 2019. It is worth $360,920 in the first year.