ALKBH5 in mouse testicular Sertoli cells regulates Cdh2 mRNA translation to maintain blood–testis barrier integrity

BACKGROUND: RNA N(6)-methyladenosine (m(6)A) is involved in mammalian spermatogenesis. In both germ cells and Leydig cells, ALKBH5 regulates spermatogenesis and androgen synthesis in an m(6)A-dependent manner. However, it is unclear whether ALKBH5 plays a role in testicular Sertoli cells, which constitute the blood–testis barrier (BTB) through cell junctions between adjacent Sertoli cells. METHODS: ALKBH5 expression in the testes of humans and mice was detected by immunohistochemical staining and immunofluorescence staining. BTB integrity was evaluated by BTB assay. m(6)A-seq was performed to screen for BTB-related molecules regulated by ALKBH5. m(6)A immunoprecipitation–quantitative real-time polymerase chain reaction (qPCR), RNA immunoprecipitation–qPCR, western blot, coimmunoprecipitation, and polysome fractionation–qPCR analyses were performed to explore the mechanisms of ALKBH5 in BTB. Transmission electron microscopy was applied to observe the BTB ultrastructure. RESULTS: ALKBH5 in Sertoli cells is related to the integrity of the BTB. Subsequently, the m(6)A level on Cdh2 mRNA, encoding a structural protein N-cadherin in the BTB, was found to be regulated by ALKBH5. IGF2BP1/2/3 complexes and YTHDF1 promoted Cdh2 mRNA translation. In addition, we found that basal endoplasmic specialization, in which N-cadherin is a main structural protein, was severely disordered in the testes of Alkbh5-knockout mice. CONCLUSIONS: Our study revealed that ALKBH5 regulates BTB integrity via basal endoplasmic specialization by affecting Cdh2 mRNA translation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s11658-022-00404-x.