CENP-E haploinsufficiency causes chromosome misalignment and spindle assembly checkpoint activation in the spermatogonia.

Background: The establishment of kinetochore-microtubule attachment is essential for error-free chromosome alignment and segregation during cell division. Defects in chromosome alignment result in chromosome instability, birth defects, and infertility. Kinesin-7 CENP-E mediates kinetochore-microtubule capture, chromosome alignment, and spindle assembly checkpoint in somatic cells, however, mechanisms of CENP-E in germ cells remain poorly understood.

Objectives: This study aimed to explore the functions of CENP-E in the proliferation and self-renewal of spermatogonia.

Materials and methods: A CENP-E heterozygous knockout strain was established in C57BL/6J mice using the CRISPR/Cas9 and Cre/LoxP system. Hematoxylin-eosin staining was performed to study the histology. The inhibition of CENP-E in the GC-1 spg cells was performed using the specific inhibitor GSK923295. The expression and localization of spermatogonial marker proteins were determined by immunofluorescence using confocal microscopy in the control and CENP-E^+/- heterozygous mouse testes. The protein expression level was analyzed using Western blot. The cell-cycle and apoptosis assay were measured using flow cytometry. In addition, karyotype analysis was performed using hypotonic preparation and chromosome spreading.

Results: Here, we reveal that CENP-E haploinsufficiency results in chromosome misalignment, spindle disorganization, and metaphase arrest in spermatogonia, which leads to the loss of spermatogonia, chromosomal instability, and spermatogenic disorders. Notably, CENP-E ablation leads to the activation of spindle assembly checkpoint and aneuploidy, which impairs the proliferation and self-renewal of spermatogonia.

Discussion and conclusion: CENP-E depletion disrupts the recruitment of key checkpoint proteins, including BubR1, Bub1, KIF2C, and Aurora B, indicating a causal relationship between chromosome misalignment and spindle assembly checkpoint activation in spermatogonia. Our findings demonstrate that CENP-E regulates kinetochore-microtubule attachment, chromosome alignment, and spindle assembly checkpoint in spermatogonia.