Germ cell-specific expression of microphthalmia-associated transcription factor mRNA in mouse testis.
The gene coding for microphthalmia-associated transcription factor (Mitf) contains many promoters that could generate multiple Mitf isoforms with distinct amino-termini, such as ubiquitously expressed Mitf-A and Mitf-H. To gain further insight into Mitf isoform multiplicity and the regulation of the promoter usage of the Mitf gene, we have analyzed the function of the amino-terminal domains of Mitf isoforms and the expression of Mitf mRNA in mouse postnatal testis, which is characterized by spermatogenesis and by a cool temperature because of its unique location. Here we show that the amino-terminal domain of Mitf-A possesses a transactivation activity, as judged by yeast expression analysis. We also show the expression of Mitf-A and Mitf-D mRNAs in testis by PCR-based methods. Moreover, in situ hybridization analysis revealed that an Mitf mRNA, probably representing Mitf-A and/or Mitf-D, is expressed in germ cells, including spermatogonia, spermatocytes that undergo meiosis, and round spermatids with the haploid genome, but is undetectable in elongated spermatids with remodeled and condensed chromatin. Notably, Mitf mRNA is undetectable in somatic Leydig cells and peritubular cells. Therefore, multiple promoters may direct differential expression of the Mitf gene in the testis and contribute to functional diversity of Mitf isoforms.
Saito
Hideo
H
Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575.
Takeda
Kazuhisa
K
Yasumoto
Ken-ichi
K
Ohtani
Haruo
H
Watanabe
Ken-ichi
K
Takahashi
Kazuhiro
K
Fukuzaki
Atsushi
A
Arai
Yoichi
Y
Yamamoto
Hiroaki
H
Shibahara
Shigeki
S
D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D005091:Exons / Q000235:genetics; D015870:Gene Expression; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D051739:Microphthalmia-Associated Transcription Factor; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013094:Spermatozoa / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014157:Transcription Factors