ABSTRACT
ASH2L is a core component of KMT2 complexes, crucial for H3K4 trimethylation. However, its role in spermatogenesis remains elusive. Here, we demonstrate an essential role of Ash2l for meiotic prophase but dispensable for mitosis in differentiated spermatogonia. Using a germ cell-specific Ash2l knockout mouse model, we reveal that Ash2l deficiency leads to meiotic arrest and sterility in both sexes. Ash2l-deficient spermatocytes exhibit failures in chromosomal synapsis associated with persistent DMC1 foci and γH2AX, resulting in meiocyte loss due to apoptosis. Conversely, Ash2l-deficient differentiated spermatogonia show normal development. Mechanistically, Ash2l deficiency results in a global loss of H3K4me3 in promoter regions and significantly decreases expression of thousands of genes. Among these are genes involved in epigenetic silencing pathways, such as H3K9 di-methylation, DNA methylation and piRNA pathways, that are crucial for transposon repression during meiotic prophase I progression. Supporting this, we observe that Ash2l mutant spermatocytes display ectopic expression of LINE1-ORF1P. Our findings therefore reveal the previously unappreciated role of ASH2L-dependent H3K4me3 modification in spermatogenesis and provide clues to the molecular mechanisms in epigenetic disorders underlying male infertility.
Footnotes
Author contributions
Conceptualization: M.-H.T.; Funding acquisition: M.-H.T., Y.C. ; Project administration: Z.L., B.R., Y.C., M.W., J.Y., T.H., X.T., Q.L., X.P.; Software: L.H.; Supervision: M.-H.T., F.L., Y.C.; Writing – original draft: M.-H.T., Y.C.; Writing – review & editing: M.-H.T., Y.C.
Funding
M.-H.T. was supported by the National Key Research and Development Program of China (2022YFC2702602 and 2021YFC2700200) and the National Natural Science Foundation of China (NSFC 31930034). F.L. was supported by the National Key Research and Development Program of China (2021YFA1300100) and the National Natural Science Foundation of China (NSFC 31925010). Y.C. was supported by the National Key Research and Development Program of China (2022YFC2702800), the National Natural Science Foundation of China (NSFC 32170861), the Science and Technology Commission of Shanghai Municipality (23ZR1469700) and the Sanofi Scholarship Program. Y.C. and Q.L. were supported by the Open Project of Peking University Third Hospital (BYSYSZKF2023004). Z.L. was supported by the National Natural Science Foundation of China (NSFC 32000585), B.R. was supported by the National Natural Science Foundation of China (NSFC 32100455).
Data availability
All sequencing data including ChIP-seq, NOMe-seq and RNA-seq data generated in this study have been deposited in GEO under accession number GSE246296.
