The Drosophila SERTAD protein Taranis determines lineage-specific neural progenitor proliferation patterns

• Published in: Developmental biology Vol. 376; no. 2; pp. 150 - 162
• Main Authors: Manansala, Miguel C., Min, Sarah, Cleary, Michael D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.04.2013
• Subjects: Animals; Cell Cycle; Cell Cycle Proteins - metabolism; Cell Differentiation; Cell Lineage; Cell Proliferation; Crosses, Genetic; Drosophila; Drosophila melanogaster; Drosophila Proteins - metabolism; Gene Expression Profiling; Gene Expression Regulation, Developmental; Immunohistochemistry - methods; In Situ Hybridization; Intermediate neural progenitor; Neural Stem Cells - cytology; Neuroblast; Neurons - cytology; Neurons - metabolism; SERTAD; Stem Cells - cytology; Taranis; Time Factors; Taranis; SERTAD; Neuroblast; Cell cycle; Intermediate neural progenitor
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2013.01.025

Neural progenitors of the Drosophila larval brain, called neuroblasts, can be divided into distinct populations based on patterns of proliferation and differentiation. Type I neuroblasts produce ganglion mother cells (GMCs) that divide once to produce differentiated progeny, while type II neuroblasts produce self-renewing intermediate neural progenitors (INPs) and thus generate lineages containing many more progeny. We identified Taranis (Tara) as an important determinant of type I lineage-specific neural progenitor proliferation patterns. Tara is an ortholog of mammalian SERTAD proteins that are known to regulate cell cycle progression. Tara is differentially-expressed in neural progenitors, with high levels of expression in proliferating type I neuroblasts but no detectable expression in type II lineage INPs. Tara is necessary for cell cycle reactivation in quiescent neuroblasts and for cell cycle progression in type I lineages. Cell cycle defects in tara mutant neuroblasts are due to decreased activation of the E2F1/Dp transcription factor complex and delayed progression through S-phase. Mis-expression of tara in type II lineages delays INP cell cycle progression and induces premature differentiation of INPs into GMCs. Premature INP differentiation can also be induced by loss of E2F1/Dp function and elevated E2F1/Dp expression suppresses Tara-induced INP differentiation. Our results show that lineage-specific Tara expression is necessary for proper brain development and suggest that distinct cell cycle regulatory mechanisms exist in type I versus type II neural progenitors. ► Tara is expressed in type I progenitors but is absent from type II progenitors. ► Tara is required for cell cycle reactivation in quiescent neuroblasts. ► Tara regulates cell cycle progression in type I neuroblast lineages. ► Tara mis-expression induces differentiation of intermediate neural progenitors. ► Tara differentially affects progenitor proliferation in type I versus type II lineages.