Neddylation is indispensable for early meiotic progression in spermatocytes via destabilizing HORMAD1 by SCF ubiquitin E3 ligase during synapsis.

BACKGROUND: The organized chromatin configuration in meiosis prophase I is crucial for spermatogenesis and male fertility, involving a series of tightly coordinated events mediated by numerous proteins. Neddylation, a ubiquitin-like post-translational modification, conjugates NEDD8 to substrate proteins and thus regulates protein degradation via activating Cullin-RING E3 ligases. Despite its importance in other cellular processes, its role in meiosis remains elusive.

METHODS: We inhibited neddylation using intratesticular MLN4924 treatment and generated germ cell-specific Nedd8-depleted male mice to study its meiotic role. Meiotic progression and chromosomal synapsis were assessed via markers of meiotic progression especially the assembly of synaptonemal complexes. Substrate-specific role of neddylation in meiosis was dissected to identify its functional targets both in vivo and in vitro.

RESULTS: Nedd8 deficiency in spermatocytes caused meiotic arrest at the zygotene stage, leading to azoospermia and infertility. Spermatocytes showed disrupted synapsis, with persistent HORMAD1 on unsynapsed axes and defective assembly of synaptonemal complex central elements. Mechanistically, neddylation mediated SKP1-Cullin1-FBXO47 complex-dependent ubiquitination and degradation of HORMAD1, a prerequisite for proper synapsis.

CONCLUSIONS: Our findings demonstrate that neddylation is essential for spermatocyte development and reveal its critical role in regulating synaptonemal complex dynamics, probably depending on SCF complex-mediated HORMAD1 degradation. This study provides insights into post-translational control of protein dynamics in meiosis and potential therapeutic targets for male infertility.