Angiotensin-converting enzyme and male fertility

Abstract

The angiotensin-converting enzyme (ACE; EC 3.4.15.1) gene (Ace) encodes both a somatic isozyme found in blood and several other tissues, including the epididymis, and a testis-specific isozyme (testis ACE) found only in developing spermatids and mature sperm. We recently used gene targeting to disrupt the gene coding for both ACE isozymes in mice and reported that male homozygous mutants mate normally but have reduced fertility; the mutant females are fertile. Here we explore the male fertility defect. We demonstrate that ACE is important for achieving in vivo fertilization and that sperm from mice lacking both ACE isozymes show defects in transport within the oviducts and in binding to zonae pellucidae. Males generated by gene targeting that lack somatic ACE but retain testis ACE are normally fertile, establishing that somatic ACE in males is not essential for their fertility. Furthermore, male and female mice lacking angiotensinogen have normal fertility, indicating that angiotensin I is not a necessary substrate for testis ACE. Males heterozygous for the mutation inactivating both ACE isozymes sire wild-type and heterozygous offspring at an indistinguishable frequency, indicating no selection against sperm carrying the mutation.Angiotensin-converting enzyme (ACE; EC 3.4.15.1) catalyzes the cleavage of C-terminal dipeptides from several substrates including angiotensin I and bradykinin (1). The gene for ACE (ACE in humans, Ace in mice) codes for both a somatic and a smaller testis-specific isozyme. Somatic ACE is anchored to the plasma membranes of vascular endothelial cells and several epithelia, including cells in the epididymis, and a soluble form is present in blood. The testis isozyme is found only in developing spermatids and in mature sperm (2-5).Somatic ACE encoded by the entire gene is composed of two homologous amino acid domains (6, 7). The testis isozyme is encoded by the second half of the gene under the control of a testis-specific promoter located within intron 12 (8). The testis isozyme has a unique N-terminal sequence determined by a testis-specific exon; its remaining sequence is identical to the C-terminal domain of somatic ACE (9-11). Transcription of testis ACE in mouse spermatogenic cells begins in late pachytene spermatocytes (3) or after meiosis (4), and ACE protein is first detected in haploid spermatids (2-4). The tissue specificity of testis ACE is achieved with a promoter sequence of 91 base pairs (12). The functions of the ACE isozymes in male reproduction are unknown.We recently generated mice carrying an insertional disruption of exon 14 of the murine Ace gene, which prevents the synthesis of both testis and somatic ACE (13). Intercrossing of heterozygous mice gave Ϸ11% homozygous mutant mice compared with the expected 25%. Compared with wild-type mice (which we designate Ace ST ͞Ace ST , hereafter abbreviated STST to indicate the presence of both the somatic and testis isozymes), the homozygous mutant (stst) mice lacking both isozymes have blood pressures reduced about 3...

Identity and transfer of male reproductive gland proteins of the dengue vector mosquito, Aedes aegypti: Potential tools for control of female feeding and reproduction

“…ACEs are found in the testes and male reproductive glands (as well as other tissues) of insects and mammals (Isaac et al, 1999;Leung and Sernia, 2003;Rylett et al, 2007) and have dramatic effects on the reproductive biology of both groups of organisms (Hagaman et al, 1998;Isaac et al, 1999;Ekbote et al, 2003;Kondoh et al, 2005). Of particular interest, the effect of male-derived ACEs on female fecundity has been investigated in the mosquito, Anopheles stephensi.…”

Male Mice That Do Not Express Group VIA Phospholipase A2 Produce Spermatozoa with Impaired Motility and Have Greatly Reduced Fertility

“…In Vivo Fertilization Assay-Superovulation of 6 -8-week-old female mice was induced by injecting pregnant mare serum gonadotropin (10 IU, intraperitoneally; Sigma) and, after 48 h, hCG (10 IU, intraperitoneal, Sigma), as described (21)(22)(23)(24). Those mice were then mated with iPLA 2 ␤ ϩ/ϩ or iPLA 2 ␤ Ϫ/Ϫ males overnight, and, after 48 h, the mice were euthanized with pentobarbital according to a protocol approved by our Animal Studies Committee.…”

Shedding of somatic angiotensin-converting enzyme (ACE) is inefficient compared with testis ACE despite cleavage at identical stalk sites

“…The somatic isoform is expressed widely at surface-fluid interfaces and plays an important role in blood pressure maintenance [1,2]. The testis isoform is limited to spermatozoa and is essential for male fertility [3,4]. Somatic ACE has a tandem repeat structure of two homologous domains, of which the second (C-terminal) domain is identical with the single domain of testis ACE, except for a unique, 36-residue, serineand threonine-rich sequence at the N-terminus of testis ACE [5,6].…”