Tebar M, Boex J J, Ten Have-Opbroek A A
Department of Pulmonology, Leiden University Medical Center, Leiden, The Netherlands.
Anat Rec. 2001 May 1;263(1):25-34. doi: 10.1002/ar.1073.
At 15 weeks after conception (a.c.), the human pulmonary acinus is lined by distal low-columnar and more proximal cuboidal cells that are successive stages in alveolar type II cell differentiation (pseudoglandular period of lung development). From 16 weeks a.c. onward, there are also 'flatter' cells that are intermediate stages in the differentiation of cuboidal type II cells into squamous type I cells (canalicular period). We investigated the role of wild-type p53 protein and the proliferation marker Ki-67 in the differentiation of type II and type I cells in these two periods. Serial sections from fetal lungs (n = 30) were immunoincubated with antibodies against p53 and Ki-67. The presence of prospective type II and type I cells was confirmed using immunohistochemistry for surfactant protein SP-A as a differentiation marker and light and electron microscopy. The p53 and Ki-67 positive nuclei were quantified per alveolar cell phenotype (i.e., low-columnar; cuboidal; flatter). The occurrence of cell apoptosis was studied using propidium iodide (PI) and 4',6'-diamino-2-phenylindol dihydrochloride (DAPI) staining. The combined increase in p53 expression and decrease in Ki-67 expression during alveolar epithelial cell differentiation suggests that wild-type p53 protein plays a role in the differentiation of alveolar type II and type I cells in the human lung, and that this function is mediated through cell cycle arrest. The rare incidence of apoptotic nuclei in alveolar type II cells, together with their absence in alveolar type I cells, supports the view that p53 is involved in the differentiation, rather than the death, of alveolar epithelial cells.
在受孕后15周（a.c.）时，人类肺腺泡由远端低柱状细胞和更靠近近端的立方体细胞构成，这些细胞是肺泡II型细胞分化的连续阶段（肺发育的假腺期）。从受孕后16周起，也有“更扁平”的细胞，它们是立方体型II型细胞向扁平型I型细胞分化的中间阶段（小管期）。我们研究了野生型p53蛋白和增殖标志物Ki-67在这两个时期II型和I型细胞分化中的作用。对30例胎儿肺的连续切片用抗p53和Ki-67抗体进行免疫孵育。使用针对表面活性蛋白SP-A的免疫组织化学作为分化标志物以及光镜和电镜来确认预期的II型和I型细胞的存在。对每种肺泡细胞表型（即低柱状；立方体型；更扁平型）的p53和Ki-67阳性细胞核进行定量。使用碘化丙啶（PI）和4',6'-二脒基-2-苯基吲哚二盐酸盐（DAPI）染色研究细胞凋亡的发生情况。肺泡上皮细胞分化过程中p53表达增加和Ki-67表达降低的共同作用表明，野生型p53蛋白在人肺肺泡II型和I型细胞的分化中起作用，并且该功能是通过细胞周期停滞介导的。肺泡II型细胞中凋亡细胞核的罕见发生率以及肺泡I型细胞中不存在凋亡细胞核，支持了p53参与肺泡上皮细胞的分化而非死亡这一观点。
