In the Drosophila larval brain, type I and type Ⅱ neuroblasts（NBs） undergo a series of asymmetric divisions which give rise to distinct progeny lineages. The intermediate neural progenitors（INPs） exist only in ty...In the Drosophila larval brain, type I and type Ⅱ neuroblasts（NBs） undergo a series of asymmetric divisions which give rise to distinct progeny lineages. The intermediate neural progenitors（INPs） exist only in type Ⅱ NB lineages. In this study, we reveal a novel function of Inscuteable（Insc） that acts to maintain type I NB lineage identity. In insc type I NB clones of mosaic analyses with a repressible cell marker（MARCM）, the formation of extra Deadpan（Dpn）tNB-like and GMC-like cells is observed. The lack of Insc leads to the defective localization and segregation of Numb during asymmetric cell division. By the end of cytokinesis, this results in insufficient Numb in ganglion mother cells（GMCs）. The formation of extra Deadpan（Dpn）tcells in insc clones is prevented by the attenuation of Notch activity. This suggests that Insc functions through the Numb/Notch signaling pathway. We also show that in the absence of Insc in type I NB lineages, the cellular identity of GMCs is altered where they adopt an INP-like cell fate as indicated by the initiation of Dpn expression accompanied by a transient presence of Earmuff（Erm）.These INP-like cells have the capacity to divide multiple times. We conclude that Insc is necessary for the maintenance of type I NB lineage identity. Genetic manipulations to eliminate most type I NBs with overproliferating type Ⅱ NBs in the larval brain lead to altered circadian rhythms and defective phototaxis in adult flies. This indicates that the homeogenesis of NB lineages is important for the adult＇s brain function.展开更多
The proteins Inscuteable and Staufen are key components during asymmetric cell division of neuroblasts for the development of Drosophila melanogaster. Expression and purification of both proteins has been a difficult ...The proteins Inscuteable and Staufen are key components during asymmetric cell division of neuroblasts for the development of Drosophila melanogaster. Expression and purification of both proteins has been a difficult task for structure-function studies. Based on codon optimization for protein expression in Escherichia coli, we have been able to produce, in soluble form, the C-terminal domains of Inscuteable and Staufen as chimeras with N-terminal maltose binding protein tag that contains a rigid linker between them for feasible crystallization. In addition, using an optimized synthetic gene, corresponding to the amino acid region 250 - 623 of Inscuteable fused to glutathione-S-transferase, low-scale expression experiments showed production of soluble protein. Finally, eukaryotic expression of Inscuteable in the methylothropic yeast Pichia pastoris failed to produce the Drosophila protein at detectable amounts, reinforcing the fact that E. coli still was the microorganism of choice for high-yield protein expression.展开更多
基金supported by the National Basic Research Program of China (No.2013CB945600)the National Natural Science Foundation of China (No.31371381)
文摘In the Drosophila larval brain, type I and type Ⅱ neuroblasts（NBs） undergo a series of asymmetric divisions which give rise to distinct progeny lineages. The intermediate neural progenitors（INPs） exist only in type Ⅱ NB lineages. In this study, we reveal a novel function of Inscuteable（Insc） that acts to maintain type I NB lineage identity. In insc type I NB clones of mosaic analyses with a repressible cell marker（MARCM）, the formation of extra Deadpan（Dpn）tNB-like and GMC-like cells is observed. The lack of Insc leads to the defective localization and segregation of Numb during asymmetric cell division. By the end of cytokinesis, this results in insufficient Numb in ganglion mother cells（GMCs）. The formation of extra Deadpan（Dpn）tcells in insc clones is prevented by the attenuation of Notch activity. This suggests that Insc functions through the Numb/Notch signaling pathway. We also show that in the absence of Insc in type I NB lineages, the cellular identity of GMCs is altered where they adopt an INP-like cell fate as indicated by the initiation of Dpn expression accompanied by a transient presence of Earmuff（Erm）.These INP-like cells have the capacity to divide multiple times. We conclude that Insc is necessary for the maintenance of type I NB lineage identity. Genetic manipulations to eliminate most type I NBs with overproliferating type Ⅱ NBs in the larval brain lead to altered circadian rhythms and defective phototaxis in adult flies. This indicates that the homeogenesis of NB lineages is important for the adult＇s brain function.
文摘The proteins Inscuteable and Staufen are key components during asymmetric cell division of neuroblasts for the development of Drosophila melanogaster. Expression and purification of both proteins has been a difficult task for structure-function studies. Based on codon optimization for protein expression in Escherichia coli, we have been able to produce, in soluble form, the C-terminal domains of Inscuteable and Staufen as chimeras with N-terminal maltose binding protein tag that contains a rigid linker between them for feasible crystallization. In addition, using an optimized synthetic gene, corresponding to the amino acid region 250 - 623 of Inscuteable fused to glutathione-S-transferase, low-scale expression experiments showed production of soluble protein. Finally, eukaryotic expression of Inscuteable in the methylothropic yeast Pichia pastoris failed to produce the Drosophila protein at detectable amounts, reinforcing the fact that E. coli still was the microorganism of choice for high-yield protein expression.
