Novel Actin-Like Proteins T-ACTIN 1 and T-ACTIN 2 Are Differentially Expressed in the Cytoplasm and Nucleus of Mouse Haploid Germ Cells

• Published in: Biology of reproduction Vol. 69; no. 2; pp. 475 - 482
• Main Authors: Tanaka, Hiromitsu, Iguchi, Naoko, Egydio de Carvalho, Carlos, Tadokoro, Yuko, Yomogida, Kentaro, Nishimune, Yoshitake
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.08.2003
• Subjects: Actins - biosynthesis; Actins - genetics; Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Blotting, Northern; Blotting, Western; Cell Nucleus - genetics; Cell Nucleus - metabolism; Cloning, Molecular; Contents; Cytoplasm - genetics; Cytoplasm - metabolism; Cytoskeletal Proteins; DNA, Complementary - biosynthesis; DNA, Complementary - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression - genetics; Gene Library; Germ Cells - metabolism; Haploidy; Hormone metabolism and regulation; Immunohistochemistry; In Situ Hybridization; Male; Mammalian male genital system; Mice; Mice, Inbred C57BL; Molecular Sequence Data; sperm; sperm motility and transport; spermatid; spermatogenesis; Spermatogenesis - physiology; testis; Testis - cytology; Testis - metabolism; Vertebrates: reproduction; Vertebrata; Spermatozoa; Mammalia; Mouse; Actin; Spermatogenesis; Semen; Rodentia; Germinal cell; Gene expression; Testicle; In vitro
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.103.015867

We isolated cDNA clones for the novel actin-like proteins T-ACTIN 1 and T-ACTIN 2, which are expressed specifically in the mouse testis. These clones were from a subtracted cDNA library that was enriched for haploid germ cell-specific cDNAs. The mRNA sizes and deduced molecular masses of t-actin 1/mACTl7b and t-actin 2/mACTl7a were 2.2 kilobases (kb) and 1.8 kb, and Mr 43.1 × 103 and Mr 47.2 × 103, respectively. The two deduced amino acid sequences had 60% homology, and they had approximately 40% homology with other actins. The T-ACTINs contained some of the conserved regions seen in other actins. Although the cellular locations of these two proteins are quite different (T-ACTIN-1 was found in the cytoplasm and T-ACTIN-2 was located in the nucleus), the expression of their proteins and mRNAs is controlled during development and limited during spermiogenesis. In contrast, only T-ACTIN-2 was present in sperm heads and tails. These results suggest that T-ACTINs play important roles in sperm function and in the specific morphogenesis of spermatozoa during spermiogenesis.