Effect of donor age on the phosphorylation of the retinoblastoma gene product in cultured human keratinocytes.
The retinoblastoma gene product (pRB) is a tumor suppressor protein. Recently, it has been shown that the phosphorylation of pRB is necessary for progression from G1 to S phase in a variety of cells. In a word, the phosphorylation of pRB accelerates cell growth. In this study, we examined the phosphorylation status of pRB in normal human keratinocytes obtained from donors aged from 1 year to 71 years. The cells of old donors (61-71 years old) presented the more dense hypophosphorylated pRB band than cells of young donors (1-19 years old). Densitometric measurement showed that 42.3% +/- 4.8% of the total pRB was hypophosphorylated in cells of young donors, while 58.1% +/- 6.9% was hypophosphorylated in those of old donors. Results indicate that more pRB is hypophosphorylated in cells of old donors. The phosphorylated status of pRB might be related to the loss of growth fraction in human keratinocytes of old donors.
Kobayashi
T
T
Department of Dermatology, Osaka University School of Medicine, Japan.
Hashimoto
K
K
Sudo
K
K
Nishimoto
S
S
Yoshikawa
K
K
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002455:Cell Division; D002478:Cells, Cultured; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D008875:Middle Aged; D010766:Phosphorylation; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000378:metabolism*
D016160:Retinoblastoma Protein