Successive increases in human cyclin A1 promoter activity during spermatogenesis in transgenic mice.
The human cyclin A1 gene is highly expressed in pachytene spermatocytes and is essential for spermatogenesis. To analyze mechanisms of cyclin A1 gene expression in vivo, we cloned a 1.3 kb fragment of the promoter upstream of the cDNA of enhanced green fluorescent protein (EGFP). Four lines of transgenic mice were generated that carried the transgene. Cyclin A1 promoter activity in the organs of the transgenic mice was analyzed using fluorescence microscopy and flow cytometry. Expression of EGFP was seen in male germ cells of all four murine lines. Spermatogonia at the basal membrane expressed low levels of EGFP, but bright green fluorescence was present in spermatocytes entering meiosis. Interestingly, a further sharp increase in EGFP expression was found in spermatocytes approximately at the stage of the first meiotic division. EGFP levels stayed high thereafter and EGFP was present in mature spermatozoa. A portion of c-kit expressing cells in the testis also expressed EGFP indicating cyclin A1 promoter activity in a subpopulation of spermatogonia. These data suggest that cyclin A1 is active not only in pachytene spermatocytes but also in earlier phases of spermatogenesis.
Müller-Tidow
Carsten
C
Department of Medicine, Hematology and Oncology, University of Münster, D-48129 Münster, Germany. muellerc@uni-muenster.de
Readhead
Carol
C
Cohen
Arthur H
AH
Asotra
Kamlesh
K
Idos
Gregory
G
Diederichs
Sven
S
Cauvet
Thomas
T
Yang
Rong
R
Berdel
Wolfgang E
WE
Serve
Hubert
H
Koeffler
H Phillip
HP
D000818:Animals; D019925:Cyclin A / Q000235:genetics* / Q000378:metabolism*; D056750:Cyclin A1; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008540:Meiosis; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D013090:Spermatocytes / Q000378:metabolism; D013091:Spermatogenesis; D013093:Spermatogonia / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism; D013737:Testis / Q000166:cytology
C503745:CCNA1 protein, human; C503747:Ccna1 protein, mouse; D019925:Cyclin A; D056750:Cyclin A1; D019009:Proto-Oncogene Proteins c-kit