Ribc1, short for RIB43A domain with coiled-coils 1, is a homolog protein of RIB43a. It is a microtubule inner protein (MIP) localized in the inner lumen of the doublet microtubules (DMTs) in mouse sperm flagella [1]. While its exact associated pathways are not fully clear, it is likely related to processes involved in sperm function and mammalian reproduction. Genetic models, such as knockout mice, are valuable tools for studying its function.

In a study using the CRISPR/Cas9 system to generate Ribc1 knockout (KO), Ribc2 KO, and Ribc1 and Ribc2 double-knockout (Ribc1/2 DKO) mice, it was found that the loss of either RIBC1 or RIBC2 alone did not impact male fertility. However, the absence of both RIBC1 and RIBC2 led to a decrease in pup numbers. Sperm motility analysis showed that Ribc1 KO spermatozoa had reduced velocity, and Ribc1/2 DKO sperm velocities were significantly lower than those of Ribc1 KO mice. Although no axonemal structural abnormalities were observed in Ribc1/2 DKO spermatozoa at the TEM level, both RIBC1 and RIBC2 function cooperatively in sperm motility [1].

In conclusion, Ribc1, along with RIBC2, plays a role in sperm motility, which in turn affects litter size in male mice. The study using Ribc1 KO and related mouse models has provided insights into the function of Ribc1 in mammalian reproduction, highlighting its importance in understanding the mechanisms underlying male fertility [1].

References:

1. Katsuma, Kento, Shimada, Keisuke, Tonai, Shingo, Miyata, Haruhiko, Ikawa, Masahito. 2025. The absence of both RIBC1 and RIBC2 induces decreased sperm motility and litter size in male mice. In Andrology, , . doi:10.1111/andr.70045. https://pubmed.ncbi.nlm.nih.gov/40265983/