Nexin-Dynein regulatory complex component DRC7 but not FBXL13 is required for sperm flagellum formation and male fertility in mice

by Akane Morohoshi, Haruhiko Miyata, Keisuke Shimada, Kaori Nozawa, Takafumi Matsumura, Ryuji Yanase, Kogiku Shiba, Kazuo Inaba, Masahito Ikawa Flagella and cilia are evolutionarily conserved cellular organelles. Abnormal formation or motility of these organelles in humans causes several syndromic diseases termed ciliopathies. The central component of flagella and cilia is the axoneme that is composed of the ‘9+2’ microtubule arrangem ent, dynein arms, radial spokes, and the Nexin-Dynein Regulatory Complex (N-DRC). The N-DRC is localized between doublet microtubules and has been extensively studied in the unicellular flagellateChlamydomonas. Recently, it has been reported that TCTE1 (DRC5), a component of the N-DRC, is essential for proper sperm motility and male fertility in mice. Further, TCTE1 has been shown to interact with FBXL13 (DRC6) and DRC7; however, functional roles of FBXL13 and DRC7 in mammals have not been elucidated. Here we show thatFbxl13 andDrc7 expression are testes-enriched in mice. AlthoughFbxl13 knockout (KO) mice did not show any obvious phenotypes,Drc7 KO male mice were infertile due to their short immotile spermatozoa. InDrc7 KO spermatids, the axoneme is disorganized and the ‘9+2’ microtubule arrangement was difficult to detect. Further, other N-DRC components fail to incorporate into the flagellum without DRC7. These results indicate thatDrc7, but notFbxl13, is essential for the correct assembly of the N-DRC and flagella.
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research