Choong P F, Martin T J, Ng K W
Department of Orthopaedics, St. Vincent's Hospital, Melbourne, Australia.
J Orthop Res. 1993 Sep;11(5):638-47. doi: 10.1002/jor.1100110505.
The responses of the immortalized rat preosteoblast UMR-201-10B to ascorbic acid (AA), 1,25(OH)2D3 (calcitriol), and retinoic acid (RA) were examined. UMR-201-10B cells have an undetectable basal alkaline phosphatase (ALP) activity that is induced after 24 h of treatment with 10(-6) M RA (4.64 +/- 0.06 mumol/h/mg of protein). The addition of 10(-8) M calcitriol resulted in a slight induction of ALP activity after 72 h (0.43 +/- 0.07 mumol/h/mg of protein). When calcitriol was added to RA, however, over the same period ALP activity was enhanced significantly compared with treatment with RA alone (RA and calcitriol, 12.29 +/- 0.86 mumol/h/mg of protein). Treatment with AA (50 micrograms/ml) alone had no effect on ALP activity but increased RA-induced ALP activity to 6.78 +/- 0.28 mumol/h/mg of protein at 24 h. In contrast, AA inhibited calcitriol-induced ALP activity after 7 days of combined treatment with calcitriol (calcitriol, 7.73 +/- 0.16 mumol/h/mg of protein; AA and calcitriol, 1.44 +/- 0.06 mumol/h/mg of protein). Individually, RA and calcitriol induced mRNA expression for ALP, matrix-gla protein (MGP), and osteopontin (OP). The steady state level of pro-alpha 1(I) collagen mRNA also was increased significantly by treatment with RA and AA individually. The combination of RA and calcitriol had a synergistic effect on ALP, OP, and especially MGP mRNA expression but significantly reduced the expression of pro-alpha 1(I) collagen mRNA. AA enhanced the effect of RA on the expression of pro-alpha 1(I) collagen, MGP, and ALP mRNAs as well as the effect of calcitriol on OP and MGP. The addition of AA to RA resulted in a decrease in the steady state level of OP, whereas its cotreatment with calcitriol caused a decrease in pro-alpha 1(I) collagen and ALP mRNA. In conclusion, these studies identify RA, calcitriol, and AA as regulators of differentiated osteoblast function.
研究了永生化大鼠前成骨细胞UMR - 201 - 10B对维生素C（AA）、1,25(OH)₂D₃（骨化三醇）和视黄酸（RA）的反应。UMR - 201 - 10B细胞的基础碱性磷酸酶（ALP）活性检测不到，在用10⁻⁶ M RA处理24小时后可被诱导（4.64±0.06 μmol/h/mg蛋白质）。添加10⁻⁸ M骨化三醇在72小时后导致ALP活性略有诱导（0.43±0.07 μmol/h/mg蛋白质）。然而，当骨化三醇与RA一起添加时，在同一时期，与单独用RA处理相比，ALP活性显著增强（RA和骨化三醇，12.29±0.86 μmol/h/mg蛋白质）。单独用AA（50 μg/ml）处理对ALP活性没有影响，但在24小时时将RA诱导的ALP活性增加到6.78±0.28 μmol/h/mg蛋白质。相反，在与骨化三醇联合处理7天后，AA抑制了骨化三醇诱导的ALP活性（骨化三醇，7.73±0.16 μmol/h/mg蛋白质；AA和骨化三醇，1.44±0.06 μmol/h/mg蛋白质）。单独来看，RA和骨化三醇诱导了ALP、基质γ-羧基谷氨酸蛋白（MGP）和骨桥蛋白（OP）的mRNA表达。单独用RA和AA处理也显著增加了前α1（I）型胶原mRNA的稳态水平。RA和骨化三醇的组合对ALP、OP，尤其是MGP的mRNA表达有协同作用，但显著降低了前α1（I）型胶原mRNA的表达。AA增强了RA对前α1（I）型胶原、MGP和ALP mRNA表达的影响，以及骨化三醇对OP和MGP的影响。在RA中添加AA导致OP稳态水平降低，而其与骨化三醇共同处理导致前α1（I）型胶原和ALP mRNA降低。总之，这些研究确定RA、骨化三醇和AA为分化成骨细胞功能的调节因子。
