器官培养中兔乳腺外植体的酪蛋白周转率

Casein turnover in rabbit mammary explants in organ culture.

作者信息

Al-Sarraj K, Newbury J, White D A, Mayer R J

出版信息

Biochem J. 1979 Sep 15;182(3):837-45. doi: 10.1042/bj1820837.

DOI:10.1042/bj1820837

PMID:518567

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1161419/

Abstract

Explants of mammary gland from mid-pregnant rabbits were cultured in medium 199 containing insulin, prolactin and cortisol, and specific anti-casein immunoglobulin G was used to measure the amount, rate of synthesis and rate of degradation of casein in the explants in the presence of hormones and after removal of hormones from previously stimulated tissue. 2. The amount of casein in particle-free supernatants prepared from mammary explants was measured by ;rocket' immunoelectrophoresis. 3. The rate of incorporation of l-[4,5-(3)H]leucine into casein was measured after isolation of the casein by immunoadsorbent chromatography and polyacrylamide-gel electrophoresis in the presence of urea and sodium dodecyl sulphate. 4. Casein accumulates in mammary explants in the presence of insulin, prolactin and cortisol, but not in the absence of hormones. Removal of hormones after 24h in culture results in a decrease in the rate of accumulation of casein in the explants. 5. Casein-synthetic rate increases in mammary explants in the presence of insulin, prolactin and cortisol, but not in the absence of hormones. Removal of hormones after 24h in culture results in continued casein synthesis at approx. 30% of the rate in the presence of hormones. The synthetic rate does not decrease to values observed in explants cultured throughout in the absence of hormones. 6. Casein is not degraded in mammary explants during a phase of rapid casein accumulation (36-72h) in the presence of hormones. Furthermore casein is not degraded when hormones are removed from the tissue after between 36 and 72h in culture. 7. Casein is glycosylated in mammary explants; the extent of glycosylation parallels the rate of synthesis. The glycosylated protein is rapidly secreted from the tissue. 8. The results are consistent with the notion that after hormonal stimulation mammary explants from mid-pregnant rabbits synthesize, glycosylate and rapidly secrete casein. Removal of hormones decreases the synthetic rate of casein, but does not cause the accumulation of a pool of degradable casein in the lobuloalveolar cells.

摘要

将妊娠中期兔的乳腺外植体培养于含有胰岛素、催乳素和皮质醇的199培养基中，并用特异性抗酪蛋白免疫球蛋白G来测定在有激素存在时以及从先前受刺激的组织中去除激素后，外植体中酪蛋白的含量、合成速率和降解速率。2. 用“火箭”免疫电泳法测定从乳腺外植体制备的无颗粒上清液中酪蛋白的含量。3. 在尿素和十二烷基硫酸钠存在的情况下，通过免疫吸附色谱法和聚丙烯酰胺凝胶电泳分离酪蛋白后，测定l-[4,5-(³)H]亮氨酸掺入酪蛋白的速率。4. 在胰岛素、催乳素和皮质醇存在时，酪蛋白在乳腺外植体中积累，而在无激素时则不积累。培养24小时后去除激素会导致外植体中酪蛋白积累速率下降。5. 在胰岛素、催乳素和皮质醇存在时，乳腺外植体中酪蛋白的合成速率增加，而在无激素时则不增加。培养24小时后去除激素会导致酪蛋白以约激素存在时速率的30%继续合成。合成速率不会降至在无激素条件下全程培养的外植体中观察到的值。6. 在激素存在下酪蛋白快速积累的阶段（36 - 72小时），乳腺外植体中的酪蛋白不会降解。此外，在培养36至72小时后从组织中去除激素时，酪蛋白也不会降解。7. 乳腺外植体中的酪蛋白会发生糖基化；糖基化程度与合成速率平行。糖基化蛋白会迅速从组织中分泌出来。8. 这些结果与以下观点一致，即妊娠中期兔的乳腺外植体在激素刺激后会合成、糖基化并迅速分泌酪蛋白。去除激素会降低酪蛋白的合成速率，但不会导致小叶腺泡细胞中可降解酪蛋白池的积累。