Homeobox transcription factor DLX4 is not necessary for skin development and homeostasis

Dlx4 is a member of a family of homeobox genes with homology to Drosophila distal‐less (dll) gene. We show that Dlx4 expression pattern partially overlaps with its cis‐linked gene Dlx3 during mouse development as well as in neonatal and adult skin. In mice, Dlx4 is expressed in the branchial arches, embryonic limbs, digits, nose, hair follicle and in the basal and suprabasal layers of mouse interfollicular epidermis. We show that inactivation of Dlx4 in mice did not result in any overtly gross pathology. Skin development, homeostasis and response to TPA treatment were similar in mice with loss of Dlx4 compared to wild‐type counterparts.     

Phylotypic expression of the bHLH genes Neurogenin2, Neurod,and Mash1 in the mouse embryonic forebrain

In the anamniote model animals, zebrafish and Xenopus laevis, highly comparable early forebrain expression patterns of proneural basic helix‐loop‐helix (bHLH) genes relevant for neurogenesis (atonal homologs, i.e., neurogenins/NeuroD and achaete‐scute homologs, i.e., Ascl/ash) were previously revealed during a particular period of development (zebrafish: 3 days; frog: stage 48). Neurogenins/NeuroD on the one hand and Ascl1/ash1 on the other hand exhibit essentially mutually exclusive spatial patterns, probably reflecting different positional information received within the neural tube, and appear to underlie glutamatergic versus GABAergic neuronal differentiation, respectively. Significant data suggest that similar complementary localizations of these proneural genes and corresponding differentiation pathways also exist in the mouse, the prominent mammalian model. The present article reports on detailed mouse brain bHLH gene expression patterns to fill existing gaps in the identification of expression domains, especially outside the telencephalon. Clearly, there are strong similarities in the complementarity of territories expressing Ascl1/Mash 1 versus neurogenins/NeuroD in the entire mouse forebrain, except for the pretectal alar plate and basal plate of prosomeres 1–3. The analysis substantiates localization of neurogenins/NeuroD in the pallium, eminentia thalami, and dorsal thalamus, and expression of Ascl1/Mash 1 in the striatal and septal subpallium, preoptic region, ventral thalamus, and hypothalamus, which is highly similar to the situation described in Xenopus and zebrafish. Thus, all three vertebrate model species display a “phylotypic stage or period” corresponding to a temporally and spatially defined control of neurogenesis during forebrain development, ultimately resulting in the differentiation of distinct populations of glutamatergic versus GABAergic neurons. J. Comp. Neurol. 518:851–871, 2010. © 2009 Wiley‐Liss, Inc.     

Dlx1基因在大鼠外胚间充质细胞中表达的研究

目的 探讨Dlxl基因在牙胚发育过程中的调控作用。方法 采用外胚间充质细胞组织块培养法；地高辛标记cDNA原位杂交检测方法和斑点杂交方法，观察Dlxl基因在大鼠外胚间充质细胞，人牙乳头细胞，人牙髓细胞中的表达情况。结果 Dlxl基因在外胚间充质细胞和人牙乳头细胞中mRNA呈强阳性表达，而在牙髓细胞中弱表达。结论 Dlxl基因是牙胚发育过程中重要的调节因子，这种调控作用具有一定的时间性与空间性，它可能主要参与调控早期未分化细胞，而对终末分化细胞作用不显著。     

Dlx5 mRNA在室管膜前下区神经干细胞中的表达规律及其对神经元分化的影响

目的研究D lx5 mRNA在培养的室管膜前下区(anterior subventricu lor zone,SVZa)神经干细胞(NSCs)中的表达规律及其对SVZa NSCs方向分化的影响。方法提取每一代培养的SVZa NSCs的总RNA,通过逆转录-聚合酶链反应(RT-PCR)检测D lx5及Er81 mRNA表达的情况;将重组质粒pEGFP-mD lx5用电穿孔的方法转染不表达D lx5 mRNA代次的NSCs,再检测D lx5 mRNA的表达情况,并将转染细胞分化后进行免疫荧光染色,分析基因转染细胞与神经元分化的关系;另外,还用100 ng/m l的骨形态发生蛋白-2(BMP-2)处理不表达D lx5 mRNA的NSCs,24 h后检测D lx5 mRNA的表达情况。最后将不同D lx5 mRNA表达情况的NSCs分化后用流式细胞仪检测神经元分化的比例。结果细胞传代至第4代时D lx5 mRNA表达消失,相应地,其神经元分化比例为(8.34±0.36)%,比表达D lx5 mRNA的第3代NSCs的(19.16±0.75)%明显下降;用D lx5基因转染该代NSCs后,外源转染基因能够使内源性D lx5 mRNA恢复表达,神经元分化比例也明显升高,为(35.66±0.58)%,免疫荧光染色也证实基因转染细胞分化成了神经元;而BMP-2处理也能诱导D lx5 mRNA重新表达,神经元分化比例也有一定程度上升,与第3代NSCs的相似,为(22.27±0.12)%。除第3代NSCs分化组与BMP-2诱导组神经元分化比例差异无统计学意义外,其余各组间两两比较差异均有统计学意义(P<0.05)。结论随着传代次数的增加,到第4代时,SVZa NSCs D lx5 mRNA表达消失,而外源性D lx5基因转染及BMP-2可以诱导其重新表达;D lx5基因能使新生大鼠来源的SVZa NSCs向神经元方向分化。     

Dlx基因在哺乳动物颌面部发育中的调控作用研究进展

<正>颌面部包括颌骨、牙齿、神经、肌肉、部分颅骨以及听觉和视觉系统等多种软硬组织,其组织发育和形态发生是一个十分复杂的过程,是上皮和间充质相互作用的结果,多种基因和信号通路包括同源盒基因(Homeobox gene,Hox)参与了这个过程。同源盒基因是一类转录因子,广泛存在于生物体内,与同源异型现象即生物在个体发育过程中身体的某一部分结构转变为相似或相关的另一