Molecular switch between cell proliferation and differentiation in the craniofacial development

热休克蛋白(HSPs)是在热休克和其他生理应激条件下诱导的，通过其分子伴侣的作用保护细胞免于死亡。在非应激条件下，热休克蛋白在细胞中结构性表达。27 kDa热休克蛋白(HSP27)被认为在细胞增殖、分化和细胞死亡的关键检查点起作用。在本研究中，我们观察了Hsp27在大鼠颌下腺导管结扎后再生腺泡细胞中的免疫定位。8周龄雄性Wistar大鼠麻醉后，用小夹子结扎右侧颌下腺主排泄管，左侧为对照组。1周后取下夹子松解结扎管。分别于…摘除后0、1、3、5、7、10、14和28d用4%多聚甲醛溶液固定颌下腺。更多的艾尔。在对照组和正常颌下腺中，HSP27免疫反应在神经和血管中可见，而在腺泡和导管细胞中未见。取出夹子3天后，在再生腺泡部远端可见少量Hsp27免疫阳性细胞。HSP27免疫反应主要定位于小而圆的上皮细胞的胞浆中。Hsp27阳性细胞在摘除夹板后7天开始增多，14天后在腺泡内未发现阳性细胞。组织学上，14天后可见正常的腺泡细胞。在颌下腺再生过程中，Hsp27阳性的上皮细胞与增殖细胞核抗原免疫反应阳性的上皮细胞没有共存，提示腺泡细胞的分化发生在摘除夹板后3~7天，Hsp27调控颌下腺再生过程中腺泡细胞的初始分化。较少

Heat shock proteins (Hsps) are induced by heat shock and other physiological stresses, and protect cells from cell death through their roles as molecular chaperone. Hsps are constitutively expressed in the cells under unstressed conditions. The 27kDa Hsp (Hsp27) has been suggested to work at crucial cellular checkpoints for proliferation, and differentiation, and cell death. Hsp27 was suggested to regulated the acinar cell differentiation and protect them from apoptosis.In the present study, we have examined the chronological immunolocalization of Hsp27 in the regenerating acinar cells after release of duct ligation in the rat submandibular gland.Male Wister rats of 8 weeks old were anesthetized and the right main excretory duct of submandibular gland were ligated by small clips and the left is control. After 1 week, clips were removed to release the duct ligation. Submandibular glands were fixed with 4% paraformaldehyde solution after 0, 1, 3, 5, 7, 10, 14 and 28 days after clip remov … More al. They were treated for immunohistochemistry of Hsp27 and PCNA.In the control and normal submandibular glands, Hsp27-immunoreactivity was observed in the nerves and blood vessels but not in the acinar and duct cells. Three days after the clip removal, small number of Hsp27-immunopositive cells was found in the distal end of regenerating acinar portion. Hsp27-immunoreacitvity was intensely localized in the cytoplasm of small and round-shaped epithelial cells. Hsp27-positive cells were increased in number until 7 days after clip removal, but no positive cells were recognized in the acini after 14 days of clip removal. Histologically, normal acinar cells were recognized after 14 days. Hsp27-positive epithelial cells were not colocalized with PCNA-immunoreactivity during the acinar regeneration.These results suggest that differentiation of acinar cells occur during 3-7 days after clip removal, and Hsp27 regulates the initial differentiation of acinar cells during submandibular gland regeneration. Less