Identification of a micropeptide and multiple secondary cell genes that modulate male reproductive success.

• publication
• 21-04-2021

Immarigeon C, Frei Y, Delbare SYN, Gligorov D, Machado Almeida P, Grey J, Fabbro L, Nagoshi E, Billeter JC, Wolfner MF, Karch F, Maeda RK. Proc Natl Acad Sci U S A 2021 Apr;118(15):. 2001897118. 10.1073/pnas.2001897118.

Even in well-characterized genomes, many transcripts are considered noncoding RNAs (ncRNAs) simply due to the absence of large open reading frames (ORFs). However, it is now becoming clear that many small ORFs (smORFs) produce peptides with important biological functions. In the process of characterizing the ribosome-bound transcriptome of an important cell type of the seminal fluid-producing accessory gland of , we detected an RNA, previously thought to be noncoding, called (). Notably, is nested in the HOX gene cluster of the Bithorax complex and is known to contain a micro-RNA within one of its introns. We find that this RNA encodes a "micropeptide" (9 or 20 amino acids, MSAmiP) that is expressed exclusively in the secondary cells of the male accessory gland, where it seems to accumulate in nuclei. Importantly, loss of function of this micropeptide causes defects in sperm competition. In addition to bringing insights into the biology of a rare cell type, this work underlines the importance of small peptides, a class of molecules that is now emerging as important actors in complex biological processes.

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