The cellular expression of GABA(A) receptor alpha1 subunit during spermatogenesis in the mouse testis.
GABA(A) receptors are pentamers in structure and are mainly composed of alpha, beta and gamma subunits. These receptors are known to function as chloride channels. We observed alpha5, beta1 and gamma3 subunit immunoreactivity in the mouse testes, specifically in the cytoplasm surrounding the nucleus in the spermatocytes and spermatids. In the current study, alpha1 subunit immunoreactivity was located in the nucleus of spermatogonia, spermatocytes and round spermatids. Immunoelectron microscopy revealed that the alpha1 subunit was localized within the nucleus of pachytene and diplotene spermatocytes in the area of condensed chromatin rather than extended chromatin. Protein sequence analysis revealed that the alpha1 subunit included DM DNA binding domains that were related to transcription factors involved in testicular differentiation in adult mice. These findings suggest that the alpha1 subunit may undertake a gene transcription function during the maturation of germ cells. a1 immunoreactivity was also detected within the mitochondria of spermatocytes and in the acrosome of round and elongated spermatids. Although the precise physiological role of the GABA(A) receptor alpha1 subunit in mitochondria remains unknown, we hypothesize that its function in the acrosome may be related to the acrosome reaction during fertilization or during spermatogenesis.
Kanbara
Kiyoto
K
Department of Anatomy and Cell Biology, Division of Life Sciences, Osaka Medical College, Daigaku-machi, Takatsuki, Osaka, Japan. an2007@art.osaka-med.ac.jp
Okamoto
Keiko
K
Nomura
Sakashi
S
Kaneko
Takeshi
T
Watanabe
Masahito
M
Otsuki
Yoshinori
Y
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011963:Receptors, GABA-A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013091:Spermatogenesis; D013094:Spermatozoa / Q000378:metabolism* / Q000648:ultrastructure; D013737:Testis / Q000378:metabolism* / Q000648:ultrastructure
C546241:Gabra1 protein, mouse; D012333:RNA, Messenger; D011963:Receptors, GABA-A