Chmp1b在II型肺泡细胞分化状态调控中的作用研究

Type II alveolar cell poorly differentiated and lamellar body disappeared after abrogation smad1 expression in embryo lung epithelium. New born transgenic mouse died. Chmp1b was identified as smad1 binding protein in mouse embryo lung. Chmp1b plays important role in many key cell physiology events such as the formation of multivesicular body. Chmp1b also distributed in cell nucleus and related to chromatin structure control and the function is unclear. Multivesicular body plays important roles on the biogenesis of lamella body. Primary experiments show the expression of Chmp1b during lung development correlate with periphery lung maturation. We plan to constitute the transgenic mice which inhibit chmp1b expression by shRNA in lung epithelium and study the function of Chmp1b in the development and maturation of periphery lung tissue. We will check the interaction pattern between smad1 and Chmp1b, analysis the mechanism and significance which control the distribution of Chmp1b in cell nucleus and cytoplasm, study the function of Chmp1b in cell nucleus and analysis its relation to cytoplasm Chmp1b. The mechanism of how chmp1b participates precious control of type II pneumonocyte differentiation status and peripheral lung development will be elucidate by combination of experiment in transgenic mice and cell level. Our research will provide new idea to find new method to promote recovery of lung disease.

敲除鼠胚胎肺上皮组织中 Smad1使Ⅱ型肺泡上皮细胞分化不良，板层小体消失，新生鼠死亡。我们发现鼠胚胎肺中 Smad1可与 Chmp1b互作。胞质中Chmp1b参与细胞多泡体形成等细胞生理活动。Chmp1b也分布在核内，可能参与染色质结构调控，功能尚不清楚。多泡体是板层小体的前体，初步研究证实Chmp1b的表达与肺发育时末梢肺组织成熟相关，我们拟构建抑制Chmp1b表达的转基因小鼠，研究 Chmp1b 在末梢肺组织发育中的作用；鉴定 Chmp1b 与Smad1 的互作模式，分析控制细胞内 Chmp1b 分布的机制及生理意义，研究核内Chmp1b的功能及其与胞质中 Chmp1b 的关系；综合动物整体水平和细胞水平的工作，阐明Chmp1b 在肺发育及Ⅱ型肺泡上皮细胞分化状态精细调控中的作用机制。这将为寻找促进肺部疾病康复的新方法提供新思路。

Chmp1b是一种ESCRT-III (Endosomal Sorting Complexes Required for Transport )相关蛋白，Chmp1a是Chmp1b同家族成员, Chmp1b/1a在多泡体的形成、自噬、细胞的膜重塑与改建中起重要作用，调控多种受体信号通路，参与胞质分裂等重要细胞生理活动。项目完成人完成了Chmp1b/1a可诱导条件敲减转基因鼠的制备，对转基因鼠表型进行了初步观察分析，研究了在肺纤维化疾病发生过程中Chmp1b/1a的作用，对二型肺泡上皮细胞诱导分化过程中Chmp1b/1a的作用机制作了分析。我们研究发现正常小鼠末梢肺组织二型肺泡上皮细胞表达Chmp1b/1a，二型肺泡上皮细胞去分化或转分化时Chmp1b/1a表达降低，其在细胞质与细胞核内的分布与细胞分化状态相关。Chmp1b/1a对与维持二型肺泡上皮细胞分化特征十分重要。Chmp1b/1a是小鼠肺纤维化发生的负相关因子，肺纤维化病灶区不存在Chmp1b/1a的表达，Chmp1b/1a通过影响受体信号通路，能够避免肺泡上皮细胞异常分化，在末梢肺组织稳态维持中起重要作用。我们构建了可诱导条件敲减的转基因载体，利用制备的Chmp1b/1a可诱导条件敲减转基因鼠与EIIa-Cre鼠交配，分别敲减Chmp1b和Chmp1a的表达，得到的转基因鼠表型正常。结合文献报道和其它研究，推测Chmp1b/1a可能在功能上存在冗余与互补。我们的工作能使我们从一个全新的角度看待评估肺纤维化病变机制，为末梢肺组织为稳态维持研究积累了新的科学资料。