# Molecular mechanisms for regulating microRNA levels in metazoans

> **NIH NIH R35** · UNIVERSITY OF FLORIDA · 2023 · $411,750

## Abstract

PROJECT SUMMARY
Gene expression, the genetic information flow from DNA to RNA to protein, involves delicate regulation by a
group of small non-coding RNAs called microRNAs (miRNAs). Dysregulated miRNA networks have been
observed in a variety of disease states including cancer, developmental defects, and neurodegenerative
diseases. In these disease states, the miRNA abundance can be affected at either the degradation or the
biogenesis steps. Target-directed miRNA degradation (TDMD) is a mechanism by which specific miRNAs
undergo degradation when extensively base-paired with their target RNAs. How TDMD may contribute to
different diseases is unclear due to the paucity of known target RNAs (or triggers) that can induce miRNA
degradation. On the other hand, Dicer functions as the central enzyme in processing precursor miRNAs into
mature miRNAs. Dicer deficiency promotes tumorigenesis, but how different miRNAs are affected by lower
levels of Dicer in cancer remains a question. To address these knowledge gaps, we will probe the molecular
regulatory mechanisms of specific miRNA abundance in metazoans focusing on three projects:
1. Expand the repertoire of metazoan TDMD triggers.
We have established CLASH, a combined biochemical and bioinformatics pipeline, for identification of TDMD
triggers in cultured cells. We will further improve CLASH for application in model organisms to identify
conserved and essential TDMD triggers.
2. Investigate the properties of effective TDMD triggers.
Known TDMD trigger sequences are concentrated in conserved regions of the mRNA 3′ UTR and non-coding
RNAs. We will investigate the importance of trigger transcripts sequences, structure and the non-coding
properties in inducing TDMD.
3. Differential Dicer processing of cellular miRNAs.
In an engineered colorectal cancer HCT116 cell line, in which Dicer expression can be fine-tuned by
doxycycline, we will determine the miRNA profile at different Dicer expression levels. Determinants for
differential responsiveness to Dicer of individual miRNAs will be probed by in vitro Dicer cleavage assays and
identification of miRNA binding proteins.
Our unique experimental approaches will provide the basis for developing novel therapeutics through
modulation of the TDMD pathway and Dicer action. Techniques and experience acquired in this project will
prepare our group for future research in exploring molecular machineries that regulate small RNAs essential
for gene expression in normal and diseased tissue.

## Key facts

- **NIH application ID:** 10622724
- **Project number:** 2R35GM128753-06
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** MINGYI XIE
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $411,750
- **Award type:** 2
- **Project period:** 2018-08-13 → 2028-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10622724

## Citation

> US National Institutes of Health, RePORTER application 10622724, Molecular mechanisms for regulating microRNA levels in metazoans (2R35GM128753-06). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10622724. Licensed CC0.

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