Haploid male germ cells-the Grand Central Station of protein transport.

Background: The precise movement of proteins and vesicles is an essential ability for all eukaryotic cells. Nowhere is this more evident than during the remarkable transformation that occurs in spermiogenesis-the transformation of haploid round spermatids into sperm. These transformations are critically dependent upon both the microtubule and the actin cytoskeleton, and defects in these processes are thought to underpin a significant percentage of human male infertility.

CBE1 Is a Manchette- and Mitochondria-Associated Protein With a Potential Role in Somatic Cell Proliferation.

Ciliated bronchial epithelium 1 (CBE1) is a microtubule-associated protein localized to the manchette and developing flagellum during spermiogenesis and is associated with sperm maturation arrest in humans. It was hypothesized that CBE1 functions in microtubule-mediated transport mechanisms and sperm tail formation. To test this hypothesis, we analyzed Cbe1 expression and localization during spermiogenesis, and in mouse inner medullary collecting duct-3 (IMCD3) cells as a model of ciliogenesis.

A splice site variant in INPP5E causes diffuse cystic renal dysplasia and hepatic fibrosis in dogs.

Ciliopathies presenting as inherited hepatorenal fibrocystic disorders are rare in humans and in dogs. We describe here a novel lethal ciliopathy in Norwich Terrier puppies that was diagnosed at necropsy and characterized as diffuse cystic renal disease and hepatic fibrosis. The histopathological findings were typical for cystic renal dysplasia in which the cysts were located in the straight portion of the proximal tubule, and thin descending and ascending limbs of Henle's loop.

Cilia-related protein SPEF2 regulates osteoblast differentiation.

Sperm flagellar protein 2 (SPEF2) is essential for motile cilia, and lack of SPEF2 function causes male infertility and primary ciliary dyskinesia. Cilia are pointing out from the cell surface and are involved in signal transduction from extracellular matrix, fluid flow and motility. It has been shown that cilia and cilia-related genes play essential role in commitment and differentiation of chondrocytes and osteoblasts during bone formation.

Formation and function of sperm tail structures in association with sperm motility defects.

Male infertility is an increasing problem partly due to inherited genetic variations. Mutations in genes involved in formation of the sperm tail cause motility defects and thus male infertility. Therefore, it is crucial to understand the protein networks required for sperm differentiation.

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

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.

KIF1-binding protein interacts with KIF3A in haploid male germ cells.

Male fertility relies on the production of functional spermatozoa. Spermatogenesis is a complex differentiation process that is characterized by meiosis and dramatic morphogenesis of haploid cells. Spermatogenesis involves active changes in the microtubular network to support meiotic divisions, cell polarization, the reshaping of the nucleus, and the formation of a flagellum.

KIF3A is essential for sperm tail formation and manchette function.

KIF3A motor protein is responsible for intraflagellar transport, which is required for protein delivery during axoneme formation in ciliated cells. The function of KIF3A during spermatogenesis is not known. In this study, we show that depletion of KIF3A causes severe impairments in sperm tail formation and interestingly, it also affects manchette organization and the shaping of sperm heads.