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Published on: June 30, 2023
MiR-20a and miR-20b negatively regulate autophagy by targeting RB1CC1/FIP200 in breast cancer cells
Shufeng Li1, Qian Qiang1, Haitao Shan1
1Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Department of Biochemistry and Molecular Biology, Medical School of Southeast University, Nanjing 210009, China.
Aims:
RB1CC1/FIP200 was essential for autophagosome formation. Therefore, RB1CC1/FIP200 cellular levels are critical for the activation of the autophagy pathways. Following the screen of miRNAs affecting RB1CC1/FIP200 level and rapamycin-induced autophagy, we discovered miR-20a and miR-20b could regulate autophagy by targeting RB1CC1/FIP200.
Main Methods:
Inhibitory effect of miR-20a and 20b on basal and rapamycin-stimulated autophagy was demonstrated using various autophagic tests including GFP-LC3 puncta analysis, LC3II/LC3I gel shift and TEM observation.
Key Findings:
We discovered RB1CC1/FIP200 as cellular targets of miR-20a and miR-20b. Upon miR-20a and miR-20b overexpression, both mRNA and protein levels of RB1CC1/FIP200 decreased. miR-20a and miR-20b target sequences present in the 3' UTR of RB1CC1/FIP200 mRNAs and introduction of mutations abolished the miR-20a and miR-20b responsiveness. In MCF7 and MDA-MB-231 breast cancer cells, miR-20a and miR-20b over-expression attenuated basal and rapamycin-induced autophagy; while suppression of miR-20a or miR-20b by specific antagomir showed normal rapamycin-induced autophagic activity.
Significance:
To our knowledge, this is the first study showing the significance of miR-20a and miR-20b regulating autophagy by targeting RB1CC1/FIP200.
Insights
MicroRNAs miR-20a and miR-20b regulate autophagy by targeting RB1CC1/FIP200. This study reveals their critical role in controlling autophagosome formation and cellular autophagy pathways.
Area of Science:
- Molecular Biology
- Cell Biology
- Autophagy Research
Background:
- RB1CC1/FIP200 is essential for autophagosome formation.
- Cellular levels of RB1CC1/FIP200 are critical for autophagy pathway activation.
Purpose of the Study:
- To investigate the role of microRNAs (miRNAs) in regulating RB1CC1/FIP200 levels and autophagy.
- To identify specific miRNAs that target RB1CC1/FIP200 and affect autophagy.
Main Methods:
- Screening of miRNAs affecting RB1CC1/FIP200 levels and rapamycin-induced autophagy.
- Utilizing autophagic tests: GFP-LC3 puncta analysis, LC3II/LC3I gel shift, and Transmission Electron Microscopy (TEM).
- Assessing the effect of miR-20a and miR-20b overexpression and suppression on RB1CC1/FIP200 levels and autophagy.
Main Results:
- RB1CC1/FIP200 identified as a direct target of miR-20a and miR-20b.
- Overexpression of miR-20a and miR-20b decreased both mRNA and protein levels of RB1CC1/FIP200.
- miR-20a and miR-20b attenuated basal and rapamycin-induced autophagy in breast cancer cells.
Conclusions:
- This study is the first to demonstrate that miR-20a and miR-20b regulate autophagy by targeting RB1CC1/FIP200.
- miR-20a and miR-20b play a significant role in controlling autophagy.
- These findings highlight a novel regulatory mechanism in autophagy.
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