A novel AluYb8 insertion-associated non-coding RNA, lncMUTYH, impairs mitochondrial function and dampens the M2-like polarization of macrophages

Abstract

An inverted AluYb8 insertion in the MUTYH intron 15 (AluYb8MUTYH variant) has been reported to be associated with reduced MUTYH1 expression and mitochondrial dysfunction with age. However, the underlying mechanism remains unknown. In this study, we identified a novel transcript associated with the AluYb8MUTYH variant, which revealed that this transcript is about 780 nucleotides in length with a poly-A tail, lacks protein-coding potential, referred to as lncMUTYH. The results from the reporter gene system confirmed that the lncMUTYH down-regulates MUTYH1 expression at the translational level. Site-directed mutagenesis on the 5′-terminal exon sequences of α-MUTYH and lncMUTYH constructs revealed that lncMUTYH can act as a trans-regulator that depends on the partial base pairing between its exonized AluYb8 sequence and the 5′UTR of α-MUTYH to impede MUTYH 1 expression. Furthermore, we have demonstrated a correlation between decreased mitochondrion-localized MUTYH1 caused by lncMUTYH and lowered levels of mitochondrial biological function indicators, such as mtDNA content, mitochondrial regulatory gene expression, oxygen consumption rate, ATP product, and mitochondrial respiratory capacity. Notably, we found that lncMUTYH inhibited the M2-like polarization of macrophages, and CD68/CD206-positive cell fractions were significantly lower in lncMUTYH ectopically expressing cells. The results confirmed that the AluYb8MUTYH-associated lncMUTYH, derived from an AluYb8 insertion mutation, acts as a trans-regulatory factor that inhibits the MUTYH1 protein expression, leading to a progressive mitochondrial dysfunction that may disrupt macrophage differentiation. In summary, lncMUTYH can contribute to AluYb8MUTYH-associated mitochondrial dysfunction with age and hamper the macrophage polarization process, potentially increasing the risk of developing age-related diseases.

Highlights

• A novel non-coding RNA was identified derived from the AluYb8 insertion in the MUTYH gene, namely lncMUTYH.

• LncMUTYH selectively decreased the MUTYH1 protein localized in mitochondrial, which is dependent on the sequence and orientation derived from AluYb8 insertion.

• Overexpression of lncMUTYH dampens the mitochondrial function and M2-like polarization of macrophages, partly due to the suppression of the MUTYH1 protein.

Keywords:

• AluYb8
• lncMUTYH
• mitochondrial dysfunction
• M2-like polarization

Acknowledgments

We would like to thank Yimei Fan (Nanjing University School of Medicine) for discussion on statistical analysis. We also would like to thank Lizhi Xu and Susu He (Nanjing University School of Medicine) for the constructive suggestion of this study.

Author contributions

Gaochao Dong: Data curation; Formal analysis; Investigation; Validation; Visualization; Writing the manuscript. Xuewen Yin: Data curation; Validation; Investigation; Visualization; Methodology. Yingkuan Liang: Data curation; Formal analysis; Investigation; Visualization; Methodology. Jingwen Chen: Data curation; Investigation; Methodology. Jie Wang: Investigation; Resources. Feng Jiang: Data analysis; Writing the manuscript. Chaochen Wang: Data analysis; Writing the manuscript. Wenwen Guo: Conceptualization; Funding acquisition; Supervision; Investigation; Methodology; Writing the manuscript. Yaping Wang: Conceptualization; Project administration; Supervision; Funding acquisition; Resources; Writing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This study was supported by grants from the National Natural Science Foundation of China (Grant No. 81771504, 82073211, 81702892, 81501205).