Metzler Melissa A, Venkatesh Srirangapatnam G, Lakshmanan Jaganathan, Carenbauer Anne L, Perez Sara M, Andres Sarah A, Appana Savitri, Brock Guy N, Wittliff James L, Darling Douglas S
Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America; Department of Biochemistry & Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America; Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and.
Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America; Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and.
PLoS One. 2015 Apr 30;10(4):e0125153. doi: 10.1371/journal.pone.0125153. eCollection 2015.
The transcription factor networks that drive parotid salivary gland progenitor cells to terminally differentiate, remain largely unknown and are vital to understanding the regeneration process.
A systems biology approach was taken to measure mRNA and microRNA expression in vivo across acinar cell terminal differentiation in the rat parotid salivary gland. Laser capture microdissection (LCM) was used to specifically isolate acinar cell RNA at times spanning the month-long period of parotid differentiation.
Clustering of microarray measurements suggests that expression occurs in four stages. mRNA expression patterns suggest a novel role for Pparg which is transiently increased during mid postnatal differentiation in concert with several target gene mRNAs. 79 microRNAs are significantly differentially expressed across time. Profiles of statistically significant changes of mRNA expression, combined with reciprocal correlations of microRNAs and their target mRNAs, suggest a putative network involving Klf4, a differentiation inhibiting transcription factor, which decreases as several targeting microRNAs increase late in differentiation. The network suggests a molecular switch (involving Prdm1, Sox11, Pax5, miR-200a, and miR-30a) progressively decreases repression of Xbp1 gene transcription, in concert with decreased translational repression by miR-214. The transcription factor Xbp1 mRNA is initially low, increases progressively, and may be maintained by a positive feedback loop with Atf6. Transfection studies show that Xbp1 activates the Mist1 promoter [corrected]. In addition, Xbp1 and Mist1 each activate the parotid secretory protein (Psp) gene, which encodes an abundant salivary protein, and is a marker of terminal differentiation.
This study identifies novel expression patterns of Pparg, Klf4, and Sox11 during parotid acinar cell differentiation, as well as numerous differentially expressed microRNAs. Network analysis identifies a novel stemness arm, a genetic switch involving transcription factors and microRNAs, and transition to an Xbp1 driven differentiation network. This proposed network suggests key regulatory interactions in parotid gland terminal differentiation.
驱动腮腺唾液腺祖细胞终末分化的转录因子网络在很大程度上仍不为人知，而对于理解再生过程至关重要。
采用系统生物学方法来测量大鼠腮腺唾液腺腺泡细胞终末分化过程中体内的mRNA和微小RNA表达。在长达一个月的腮腺分化期间，利用激光捕获显微切割（LCM）在不同时间点特异性分离腺泡细胞RNA。
微阵列测量结果聚类表明表达分为四个阶段。mRNA表达模式表明过氧化物酶体增殖物激活受体γ（Pparg）具有新作用，其在出生后中期分化过程中与几个靶基因mRNA一起短暂增加。79种微小RNA在不同时间有显著差异表达。mRNA表达的统计学显著变化谱，结合微小RNA与其靶mRNA的相互关联，提示存在一个假定的网络，涉及Klf4（一种分化抑制转录因子），其在分化后期随着几种靶向微小RNA增加而减少。该网络提示一个分子开关（涉及PR结构域蛋白1（Prdm1）、Sox11、配对盒蛋白5（Pax5）、微小RNA - 200a和微小RNA - 30a）逐渐减少对X盒结合蛋白1（Xbp1）基因转录的抑制，同时微小RNA - 214的翻译抑制也减少。转录因子Xbp1 mRNA最初较低，逐渐增加，并可能通过与活化转录因子6（Atf6）的正反馈环得以维持。转染研究表明Xbp1激活Mist1启动子[已校正]。此外，Xbp1和Mist1各自激活腮腺分泌蛋白（Psp）基因，该基因编码一种丰富的唾液蛋白，是终末分化的标志物。
本研究确定了Pparg、Klf4和Sox11在腮腺腺泡细胞分化过程中的新表达模式，以及众多差异表达的微小RNA。网络分析确定了一个新的干性臂、一个涉及转录因子和微小RNA的遗传开关，以及向由Xbp1驱动的分化网络的转变。这个提出的网络提示了腮腺终末分化中的关键调控相互作用。
