A Mechanosensitive Channel, Mouse Transmembrane Channel-Like Protein 1 (mTMC1) Is Translated from a Splice Variant <i>mTmc1ex1</i> but Not from the Other Variant <i>mTmc1ex2</i>
Mechanical stimuli caused by sound waves are detected by hair cells in the cochlea through the opening of mechanoelectrical transduction (MET) channels. Transmembrane channel-like protein 1 (TMC1) has been revealed to be the pore-forming component of the MET channel. The two splice variants for mous...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-09-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/21/18/6465 |
| Summary: | Mechanical stimuli caused by sound waves are detected by hair cells in the cochlea through the opening of mechanoelectrical transduction (MET) channels. Transmembrane channel-like protein 1 (TMC1) has been revealed to be the pore-forming component of the MET channel. The two splice variants for mouse <i>Tmc1</i> (<i>mTmc1ex1</i> and <i>mTmc1ex2</i>) were reported to be expressed in the cochlea of infant mice, though only the sequence of <i>mTmc1ex2</i> had been deposited in GenBank. However, due to the presence of an upstream open reading frame (uORF) and the absence of a typical Kozak sequence in <i>mTmc1ex2</i>, we questioned whether mTMC1 was translated from <i>mTmc1ex2</i>. Therefore, in this study, we evaluated which splice variant was protein-coding mRNA. Firstly, the results of RT-PCR and cDNA cloning of <i>mTmc1</i> using mRNA isolated from the cochlea of five-week-old mice suggested that more <i>Tmc1ex1</i> were expressed than <i>mTmc1ex2</i>. Secondly, mTMC1 was translated from <i>mTmc1ex1</i> but not from <i>mTmc1ex2</i> in a heterologous expression system. Finally, analyses using site-directed mutagenesis revealed that the uORF and the weak Kozak sequence in <i>mTmc1ex2</i> prevented the translation of mTMC1 from <i>mTmc1ex2</i>. These results suggest that <i>mTmc1ex1</i> plays a main role in the expression of mTMC1 in the mouse cochlea, and therefore, <i>mTmc1ex1</i> should be the mRNA for mTMC1 hereafter. |
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| ISSN: | 1661-6596 1422-0067 |