Aluminum exposure impairs the reproductive function of male mice by inhibiting the AKAP4/cAMP/PKA signaling pathway and inducing mitochondrial apoptosis

Aluminum (Al), a widely distributed environmental heavy metal, has attracted growing attention for its reproductive toxicity. The present study aimed to examine the toxicological impact of AlCl₃ on the male reproductive system and delineate its molecular basis, with emphasis on the involvement of the AKAP4-regulated cAMP/PKA signaling pathway in mitochondrial function and apoptosis. Using an AlCl₃-exposed mouse model and GC-2spd cells, together with Western blotting, immunofluorescence, and mitochondrial functional assays, Al accumulation in testicular tissue was observed, accompanied by pathological injury, reduced sex hormone levels, and abnormal sperm parameters. Mechanistic analysis in vitro demonstrated marked suppression of AKAP4 expression in GC-2spd cells following AlCl₃ treatment, resulting in diminished cAMP/PKA activity. The consequent reduction in p-BADSer155 phosphorylation, coupled with elevated BAD expression, triggered mitochondrial dysfunction—evidenced by decrease in ATP production and reduced membrane potential—and initiated apoptosis, characterized by Bax/Bcl-2 disequilibrium, Cytochrome C release, and caspase-3 activation. Gene editing further confirmed that AKAP4 overexpression alleviated AlCl₃-induced inhibition of the cAMP/PKA pathway, mitochondrial dysfunction, and apoptosis in GC-2spd cells. Collectively, these results identify the AKAP4–cAMP/PKA–BAD phosphorylation axis as a core mediator of Al-induced reproductive toxicity, offering mechanistic insight into male infertility associated with heavy metal exposure and indicating AKAP4 as a potential therapeutic target.