SPATA6

Cilia effects upon perturbation of SPATA6

Loss-of-function effect:

Acephalic sperm: head-tail detachment from failed connecting piece assembly (mouse knockout, PMID 25605924)

Phenotypes

Mouse phenotype:

Spata6-/- knockout mice (Yuan et al. 2015, PNAS, PMID 25605924) display male infertility with acephalic spermatozoa: failure of connecting piece development during late spermiogenesis produces headless spermatozoa in epididymis and ejaculate. SPATA6 is required for assembly of segmented columns and capitulum of the sperm connecting piece. Mechanism: SPATA6 interacts with myosin light-chain and heavy-chain subunits (MYL6) to mediate myosin-based microfilament transport during sperm head-tail conjunction. Similar ultrastructural defects (acephalic spermatozoa syndrome, ASS) reported in human infertility patients, but no patient mutations in SPATA6 itself have been identified to date — only SUN5 and PMFBP1 mutations cause human ASS clinically.

Subcellular localization

sperm connecting piece, segmented columns, capitulum

References: PMID:25605924

Functional category

• Reproduction & sperm
• Trafficking (BBSome, small GTPases, vesicular transport, ATPases)

Function

SPATA6 is a testis-specific protein required for normal assembly of the sperm connecting piece, including segmented columns and capitulum, which mediate tight head-tail conjunction during late spermiogenesis. No patient mutations in SPATA6 have been reported; clinical relevance is based on mouse knockout evidence (Yuan et al. 2015, PNAS, PMID 25605924).