SPEF2 functions in microtubule-mediated transport in elongating spermatids to ensure proper male germ cell differentiation

Abstract

Sperm differentiation requires specific protein transport for correct sperm tail formation and head shaping. A transient microtubular structure, the manchette, appears around the differentiating spermatid head and serves as a platform for protein transport to the growing tail. Sperm flagellar 2 (SPEF2) is known to be essential for sperm tail development. In this study we investigated the function of SPEF2 during spermatogenesis using a male germ cell-specific Spef2 knockout mouse model. In addition to defects in sperm tail development, we observed a duplication of the basal body and failure in manchette migration resulting in an abnormal head shape. We identified cytoplasmic dynein 1 and GOLGA3 as novel interaction partners for SPEF2. SPEF2 and dynein 1 colocalize in the manchette and the inhibition of dynein 1 disrupts the localization of SPEF2 to the manchette. Furthermore, the transport of a known SPEF2-binding protein, IFT20, from the Golgi complex to the manchette was delayed in the absence of SPEF2. These data indicate a possible novel role of SPEF2 as a linker protein for dynein 1-mediated cargo transport along microtubules.

Biallelic mutations in Sperm flagellum 2 cause human multiple morphological abnormalities of the sperm flagella (MMAF) phenotype

“…A nonsense mutation in exon 28 caused PCD in mice. Lack of the full‐length SPEF2 protein is the basis of the sperm tail defective phenotype in multiple animal models . In our present work, the patient harbored biallelic mutations and exhibited a typical MMAF phenotype without PCD, mainly because the biallelic mutations generated truncated proteins that contained the full N‐terminus, which was confirmed by the constructed mutant plasmids (Figure B).…”

“…Previous studies have promulgated the significance of SPEF2 in spermatogenesis . An intronic insertion within the Spef2 gene resulted in aberrant splicing and caused immotile and malformed sperm tails in pigs .…”

“…Causative nonsense mutations in Spef2 caused short tails and an abnormal flagellar shape in a mouse model . Conditional knockout Spef2 in male germ cells produced short and thick tailed sperm with microtubule structural defects, including disorganization or the absence of central pair microtubules and a complete disorganization of the axoneme, mitochondria, and outer dense fibers, and a lack of organized fibrous sheath structures in the mouse model . According to the latest reports, the homozygous mutations in SPEF2 induced the human sperm MMAF phenotype, accompanied by an absence of the central pair complex (9 + 0 conformation) and defects in the principal piece of the sperm flagella .…”

DNAH6is a novel candidate gene associated with sperm head anomaly

“…Acroplaxome, a subacrosomal cytoskeletal plate towards which Golgi‐derived vesicles fuse, is one of the major complexes involved in acrosome formation (Kierszenbaum & Tres, ). Many dynein proteins are involved in the Golgi transport and maintenance (Asante et al., ; Chanduri et al., ; Jaarsma & Hoogenraad, ; Lehti, Zhang, Kotaja, & Sironen, ; Schroeder & Vale, ). Also in most cells, the Golgi lies adjacent to the centrioles.…”

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

“…At the early steps of spermiogenesis, the axoneme composed of microtubules elongates and a transient microtubule structure called the manchette is assembled [36]. The manchette is involved in sperm head elongation, and abnormal head morphology is often related to defects in the formation, function, and movement of the manchette [37][38][39][40]. To observe the axoneme and manchette, we performed immunofluorescence using an anti-α-tubulin antibody on spermatogenic cells obtained from seminiferous tubules.…”