| Co-Investigator(Kenkyū-buntansha) |
HORI Chiyo University of Tokyo, Faculty of Medicine, 医学部, 教務職 (10157050)
KASAMA Takeshi University of Tokyo, Faculty of Medicine, 医学部, 教務職 (80124668)
SHIMIZU Takao University of Tokyo, Faculty of Medicine, 医学部, 助教授 (80127092)
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| Research Abstract |
Harderian gland was first reported in 1694, three hundred years ago. It has several functions as an extraretinal photoreceptor, regulation of the circadian rhythm and its pheromonal effect, in addition to the excretion of lipids as lubricant. This gland is an interesting model organ for the study of circadian rhythm.
In the present study, we found a novel polypeptide growth factor, named "Harderian gland-derived growth factor (HGDGF)" , which has been purified approximately 43,000-fold, to apparent homogeneity, from guinea pig Harderian gland by column chromatographies on TSKgel DEAE-5PW, Blue Sepharose CL-6B, and Superose 12. This growth factor was eluted from TSKgel DEAE-5PW at 0.20-0.35 M MaCl, with a linear gradient of 0.15-0.80 M NaCl, and at 2.20 M NaCl from Blue Sepharose CL-6B, respectively. The activity of HGDGF toward human embryonic cells (TIG-3) was quantitated by ^3H -thymidine incorporation for 48 h, which was stimulated in a linear and dose dependent manner. The final yield was approximately 10%. The purified growth factor has a molecular weight of apporximately 14,000, as determined by SDS-polyacrylamide gel electrophoresis and also by molecular sieve column chromatography. HGDGF was labile to treatment with SH reagents or acetic acid. Both trypsin digestion and boiling decreased the activity of HGDGF. Its pI was 5.1. This factor stimulated the multiplication of TIG-3 cells but had no effect on K2T1 cells which require fibroblast growth factor (FGF) for growth. HGDGF appears to differ from other growth factors, suggesting that it is a previously undescribed growth factor.
The characterization of this growth factor will give us important informations in the understanding of the regulation of circadian rhythm.
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