Mir20b is a microRNA that plays significant roles in multiple biological processes and diseases. It can regulate gene expression through RNA silencing under normal physiological conditions, and is involved in pathways related to cell proliferation, apoptosis, autophagy, and migration [5]. Aberrant expression of Mir20b has been associated with tumorigenesis and cancer development, and it may also have a role in the innate immune response and neurodegenerative disorders [2,3]. Genetic models, such as KO/CKO mouse models, can be valuable for studying its functions.

In non-alcoholic fatty liver disease (NAFLD), Mir20b specifically targets PPARA, a key regulator in hepatic lipid metabolism. In mouse models, overexpression of Mir20b in hepatocytes led to increased hepatic lipid accumulation and triglyceride levels, reduced fatty acid oxidation and mitochondrial biogenesis. The therapeutic effect of the PPARα agonist fenofibrate was suppressed in Mir20b-introduced mice. Conversely, inhibition of Mir20b increased fatty acid oxidation and uptake, improved insulin sensitivity, and decreased NAFLD progression. The combination of fenofibrate and anti-Mir20b had a synergic effect in improving NAFLD in methionine-deficient diet-fed mice [1]. In breast cancer, adipose-derived stem cells can promote tumor metastasis by inhibiting Mir20b through the stem cell factor-c-Kit/MAPK-p38/E2F1 signaling cascade. Downregulation of Mir20b activates the HIF-1α/VEGFA pathway, inducing epithelial-to-mesenchymal transition (EMT) and metastasis of breast cancer cells. Upregulation of Mir20b abrogates the activation of EMT and lung metastasis of breast cancer cells cocultured with adipose-derived stem cells [4].

In conclusion, Mir20b is involved in regulating crucial biological processes such as lipid metabolism in the liver and cancer cell metastasis. Studies using mouse models have revealed its role in NAFLD and breast cancer, providing insights into potential therapeutic targets for these diseases.

References:

1. Lee, Yo Han, Jang, Hyun-Jun, Kim, Sounkou, Nam, Dougu, Choi, Jang Hyun. 2021. Hepatic MIR20B promotes nonalcoholic fatty liver disease by suppressing PPARA. In eLife, 10, . doi:10.7554/eLife.70472. https://pubmed.ncbi.nlm.nih.gov/34964438/

2. de Lima, Jordana Dinorá, de Paula, André Guilherme Portela, Yuasa, Bruna Sadae, Winter Boldt, Angelica Beate, Braga, Tárcio Teodoro. 2023. Genetic and Epigenetic Regulation of the Innate Immune Response to Gout. In Immunological investigations, 52, 364-397. doi:10.1080/08820139.2023.2168554. https://pubmed.ncbi.nlm.nih.gov/36745138/

3. Wang, Ruizhi, Chopra, Nipun, Nho, Kwangsik, Counts, Scott E, Lahiri, Debomoy K. 2022. Human microRNA (miR-20b-5p) modulates Alzheimer's disease pathways and neuronal function, and a specific polymorphism close to the MIR20B gene influences Alzheimer's biomarkers. In Molecular psychiatry, 27, 1256-1273. doi:10.1038/s41380-021-01351-3. https://pubmed.ncbi.nlm.nih.gov/35087196/

4. Xu, Haiqian, Li, Wenjie, Luo, Sai, Yuan, Jian, Hao, Lijun. 2019. Adipose derived stem cells promote tumor metastasis in breast Cancer cells by stem cell factor inhibition of miR20b. In Cellular signalling, 62, 109350. doi:10.1016/j.cellsig.2019.109350. https://pubmed.ncbi.nlm.nih.gov/31254605/

5. İlhan, Ahmet, Golestani, Shayan, Shafagh, Seyyed Ghavam, Khalatbari, Fateme, Yaseri, Amirhossein Fakhre. 2023. The dual role of microRNA (miR)-20b in cancers: Friend or foe? In Cell communication and signaling : CCS, 21, 26. doi:10.1186/s12964-022-01019-7. https://pubmed.ncbi.nlm.nih.gov/36717861/