The transcriptional factor Apt regulates neuroblast differentiation through activating CycE expression

Polyploidy in development and tumor models in Drosophila

Polyploidy, a cell status defined as more than two sets of genomic DNA, is a conserved strategy across species that can increase cell size and biosynthetic production, but the functional aspects of polyploidy are nuanced and vary across cell types. Throughout Drosophila developmental stages (embryo, larva, pupa and adult), polyploid cells are present in numerous organs and help orchestrate development while contributing to normal growth, well-being and homeostasis of the organism. Conversely, increasing evidence has shown that polyploid cells are prevalent in Drosophila tumors and play important roles in tumor growth and invasiveness. Here, we summarize the genes and pathways involved in polyploidy during normal and tumorigenic development, the mechanisms underlying polyploidization, and the functional aspects of polyploidy in development, homeostasis and tumorigenesis in the Drosophila model.

Evolutionarily Conserved Roles for Apontic in Induction and Subsequent Decline of Cyclin E Expression

Cyclin E is a key factor for S phase entry, and deregulation of Cyclin E results in developmental defects and tumors. Therefore, proper cycling of Cyclin E is crucial for normal growth. Here we found that transcription factors Apontic (Apt) and E2f1 cooperate to induce cyclin E in Drosophila. Functional binding motifs of Apt and E2f1 are clustered in the first intron of Drosophila cyclin E and directly contribute to the cyclin E transcription. Knockout of apt and e2f1 together abolished Cyclin E expression. Furthermore, Apt up-regulates Retinoblastoma family protein 1 (Rbf1) for proper chromatin compaction, which is known to repress cyclin E. Notably, Apt-dependent up-regulation of Cyclin E and Rbf1 is evolutionarily conserved in mammalian cells. Our findings reveal a unique mechanism underlying the induction and subsequent decline of Cyclin E expression.

Drosophila Embryonic CNS Development: Neurogenesis, Gliogenesis, Cell Fate, and Differentiation

The Drosophila embryonic central nervous system (CNS) is a complex organ consisting of ∼15,000 neurons and glia that is generated in ∼1 day of development. For the past 40 years, Drosophila developmental neuroscientists have described each step of CNS development in precise molecular genetic detail. This has led to an understanding of how an intricate nervous system emerges from a single cell. These studies have also provided important, new concepts in developmental biology, and provided an essential model for understanding similar processes in other organisms. In this article, the key genes that guide Drosophila CNS development and how they function is reviewed. Features of CNS development covered in this review are neurogenesis, gliogenesis, cell fate specification, and differentiation.

Drosophila as a Model for Developmental Biology: Stem Cell-Fate Decisions in the Developing Nervous System

Stem cells face a diversity of choices throughout their lives. At specific times, they may decide to initiate cell division, terminal differentiation, or apoptosis, or they may enter a quiescent non-proliferative state. Neural stem cells in the Drosophila central nervous system do all of these, at stereotypical times and anatomical positions during development. Distinct populations of neural stem cells offer a unique system to investigate the regulation of a particular stem cell behavior, while comparisons between populations can lead us to a broader understanding of stem cell identity. Drosophila is a well-described and genetically tractable model for studying fundamental stem cell behavior and the mechanisms that underlie cell-fate decisions. This review will focus on recent advances in our understanding of the factors that contribute to distinct stem cell-fate decisions within the context of the Drosophila nervous system.