Expression of Luteinizing Hormone (LH) Subunit Genes in Mouse Testis

Gonadotropins are heterodimers consisting an alpha chain (Cgα) and a beta chain. Interestingly, presence of complicated LH-β transcripts in rat testis was accidently found; testicular LH-β transcripts were confined in seminiferous tubules to spermatids, and the translated products were localized in the elongated spermatids. We hypothesized that mouse testis has potential to produce the tissue specific LH-β with similar structure to the rat testicular forms. To verify our hypothesis, we examined the adult mouse (ICR) testis using RT-PCR and immunohistochemistry. The PCR revealed the presence of the identical products in the reactions for three LH subunit types. The expected product sizes for mouse Cgα and LH-β known as pituitary type were 224 bp and 503 bp, respectively. The testicular type LH-β products were produced by a primer set based on the rat sequences, with unexpected size of 800 bp. Sequencing revealed that the proximal and distal parts (2-82 and 661- 773 bp, respectively) were homologous to rat testicular LH-β cDNA, and middle part (83-660 bp) was a unique mouse-specific region. Both Cgα and LH-β positive signals were in the round and elongated spermatids and mature sperms, and the LH-β signals were more intense. In conclusion, our study demonstrated that the presence and localization of the LH subunits in mouse testis. Further studies will be needed to understand the precise structure and function of mouse testicular LH.