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Published on: August 21, 2014
The microRNA miR-7 regulates Tramtrack69 in a developmental switch in Drosophila follicle cells
Yi-Chun Huang1, Laila Smith, John Poulton
1Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA.
Abstract:
Development in multicellular organisms includes both small incremental changes and major switches of cell differentiation and proliferation status. During Drosophila oogenesis, the follicular epithelial cells undergo two major developmental switches that cause global changes in the cell-cycle program. One, the switch from the endoreplication cycle to a gene-amplification phase, during which special genomic regions undergo repeated site-specific replication, is attributed to Notch downregulation, ecdysone signaling activation and upregulation of the zinc-finger protein Tramtrack69 (Ttk69). Here, we report that the microRNA miR-7 exerts an additional layer of regulation in this developmental switch by regulating Ttk69 transcripts. miR-7 recognizes the 3' UTR of ttk69 transcripts and regulates Ttk69 expression in a dose-dependent manner. Overexpression of miR-7 effectively blocks the switch from the endocycle to gene amplification through its regulation of ttk69. miR-7 and Ttk69 also coordinate other cell differentiation events, such as vitelline membrane protein expression, that lead to the formation of the mature egg. Our studies reveal the important role miR-7 plays in developmental decision-making in association with signal-transduction pathways.
Insights
MicroRNA miR-7 regulates Tramtrack69 (Ttk69) during Drosophila oogenesis, controlling cell cycle switches. This discovery reveals miR-7
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Multicellular development involves cell differentiation and proliferation changes.
- Drosophila oogenesis features major cell-cycle switches in follicular epithelial cells.
- The switch from endoreplication to gene amplification is linked to Notch, ecdysone, and Ttk69.
Purpose of the Study:
- To investigate the role of microRNA miR-7 in regulating developmental switches during Drosophila oogenesis.
- To elucidate the mechanism by which miR-7 influences Ttk69 expression and cell-cycle progression.
Main Methods:
- Analysis of miR-7 binding to the 3' UTR of ttk69 transcripts.
- Experimental manipulation of miR-7 levels (overexpression) to observe effects on cell-cycle switches.
- Assessment of Ttk69 expression and downstream differentiation events.
Main Results:
- miR-7 directly targets and regulates Ttk69 transcripts in a dose-dependent manner.
- Overexpression of miR-7 inhibits the transition from endocycle to gene amplification by controlling Ttk69.
- miR-7 and Ttk69 cooperate in regulating differentiation events, including vitelline membrane protein expression.
Conclusions:
- miR-7 acts as a crucial regulator in the developmental switch from endocycle to gene amplification during oogenesis.
- miR-7, in conjunction with Ttk69, plays a significant role in cell differentiation and egg maturation.
- This study highlights the intricate role of microRNAs in developmental decision-making pathways.
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