Jaskoll T F, Don-Wheeler G, Johnson R, Slavkin H C
Laboratory for Developmental Biology, School of Dentistry, University of Southern California, Los Angeles 90089-0191.
Cell Differ. 1988 Jul;24(2):105-17. doi: 10.1016/0045-6039(88)90062-0.
The timing, position and mechanism(s) for determining type II cytodifferentiation during mammalian lung development are not known. To approach this problem, we have cultured Theiler stage 16 embryonic B10.A strain mouse lung primordia (12-days gestation, E12) in serumless, chemically defined medium in the presence or absence of dexamethasone (DEX) for periods up to 27 days in vitro. Morphogenesis and cytodifferentiation were evaluated by light and transmission electron microscopy and immunochemical techniques. Pulmonary surfactant-associated apoproteins (PSAP) were initially expressed by type II cells at 16.5-day gestation in vivo. DEX-supplementation to the culture medium resulted in the accelerated expression of PSAP; the apoprotein isoforms (A1, A2, and A3) produced in vitro were comparable to those synthesized during fetal and postnatal in vivo development by high resolution, two-dimensional gel electrophoresis coupled with immunoblot staining. Cultures without DEX produced PSAP A2 and A3 isoforms, but did not produce A1 (26-31 kDa, pI 5.2-5.3). DEX-treated cultures produced more lamellar bodies within type II cells than non-treated controls. The results demonstrate that long-term cultures of embryonic lung primordia express morphogenesis, cytodifferentiation and the synthesis and secretion of PSAP in the absence of exogenous hormones or growth factors. The data set further supports the hypothesis that morphogenesis and type II cytodifferentiation are regulated by autocrine and paracrine factors intrinsic to the embryonic lung developmental program and independent of exogenous hormone controls.
在哺乳动物肺发育过程中确定II型细胞分化的时间、位置和机制尚不清楚。为了解决这个问题，我们将Theiler 16期胚胎B10.A品系小鼠肺原基（妊娠12天，E12）在无血清、化学成分明确的培养基中，在有或没有地塞米松（DEX）的情况下体外培养长达27天。通过光学显微镜、透射电子显微镜和免疫化学技术评估形态发生和细胞分化。肺表面活性物质相关载脂蛋白（PSAP）最初在体内妊娠16.5天时由II型细胞表达。向培养基中添加DEX导致PSAP表达加速；通过高分辨率二维凝胶电泳结合免疫印迹染色，体外产生的载脂蛋白异构体（A1、A2和A3）与胎儿和出生后体内发育过程中合成的异构体相当。未添加DEX的培养物产生PSAP A2和A3异构体，但不产生A1（26 - 31 kDa，pI 5.2 - 5.3）。与未处理的对照相比，DEX处理的培养物在II型细胞内产生更多板层小体。结果表明，胚胎肺原基的长期培养在没有外源激素或生长因子的情况下表达形态发生、细胞分化以及PSAP的合成和分泌。该数据集进一步支持了以下假设，即形态发生和II型细胞分化受胚胎肺发育程序固有的自分泌和旁分泌因子调节，且独立于外源激素控制。
