QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 17 March 2004
doi: 10.1242/dev.01055

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Quan, X.-J. Articles by Hassan, B. A. Search for Related Content PubMed PubMed Citation Articles by Quan, X.-J. Articles by Hassan, B. A.

Evolution of neural precursor selection: functional divergence of proneural proteins

¹ Laboratory of Neurogenetics, Department of Human Genetics, Flanders Interuniversity Institute for Biotechnology (VIB), KU Leuven, 3000 Leuven, Belgium
² Developmental Biology unit, Department of Molecular Biomedical Research, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, 9000 Ghent, Belgium
³ Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
⁴ Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA

View larger version (76K): [in a new window]   Fig. 1. The proneural activities of Atonal-related proteins. (A-D) Whole-mount in situ hybridisation with an N-tubulin probe to visualise neurogenesis in Xenopus embryos at stage 15. (A) Uninjected embryos. (B) 500 pg Ngn1 mRNA. (C) 500 pg Ato mRNA. (D) 500 pg Math1 mRNA. (E) Part of a wild-type fly wing showing no sensory bristles along the AP axis. (F) A uasMath1/+; dppGal4/+ wing. (G) A uasngn1/+; dppGal4/+ wing. (H) Quantitative analysis of the number of ectopic bristles per fly induced by expression of MATH1 or NGN1 using dppGal4 driver, `n' is the number of flies counted. (I-K) Third instar larval (L3) wing discs stained with anti-ß-GAL (green) and proneural antibodies (red). (I) An A101/TM6 wing disc. (J) A uasato,dppGal4/A101 wing disc, anti-ATO (red) and anti-ß-GAL (green). (K) A uasngn1, dppGal4/A101 wing disc, anti-NGN1 (red), anti-ß-GAL (green). (L-N) L3 wing discs stained with anti-ASE. (L) A wild-type fly (CS) wing disc. (M) A uasato,dppGal4/TM6 wing disc. (N) A uasngn1, dppGal4/TM6 wing disc. (O,P) Late stage embryos stained with 22C-10 (green) and anti-NGN1 (red). (O) A CS embryo. (P) A daGal4/uasngn1 embryo. (Q) A uasngn1;Gal4-7,ato1/ato1 L3 eye disc stained with anti-SENS. (Inset) A uasngn1;Gal4-7,ato1/TM6 L3 eye disc stained with anti-SENS revealing the R8 cells.

View larger version (41K): [in a new window]   Fig. 4. NGN proteins and ATO proteins interact with different Znfinger proteins. (A) A scutellum of a uassens/+; C5Gal4/+ fly. Some ectopic microchaetes are indicated by arrows. (B) Ectopic microchaete on a uasMath1/+; C5Gal4/+ fly scutellum. (C) Ectopic microchaete on a uassens/+; C5Gal4/uasngn1 fly scutellum. (D) A scutellum of uassens/+; uasMath1/+; C5Gal4/+ fly. (E) Quantitative analysis of the effect of SENS on NGN1 and MATH1. (F-K) Detection of N-tubulin expression via whole-mount in situ hybridization in stage 19 Xenopus embryos, injected or co-injected with different mRNAs into a single blastomere at two-cell stage. (F) 250 pg X-MyT1 mRNA. (G) 250 pg Ngn1 mRNA. (H) 1000 pg Math1 mRNA. (I) 250 pg X-MyT1 and 250 pg Ngn1 mRNAs. (J) 250 pg X-MyT1 and 1000 pg Ato mRNAs. (K) 250 pg X-MyT1 and 1000 pg Math1 mRNAs.

View larger version (63K): [in a new window]   Fig. 2. Differential encoding of proneural activity in the bHLH domains of NGN proteins and ATO proteins. (A) The basic domains of ATO (red) and NGN1 (purple). Group-specific amino acids are in green. (B) Schematic representation of NGNbATO with exchanged amino acids in red. (C) Quantitative analysis of proneural activity of misexpressed ATO, NGN1, NGNbATO in a wild-type background. (Inset) A wing from a uasngnbato/+; dppGal4/+ fly. (D) Schematic representation of ATObNGN with the exchanged amino acids in purple. (E,F) N-tubulin stained Xenopus embryo at stage 19, injected with different mRNAs into one cell (right side) of two cell-stage embryos. (E) 1000 pg of Ato mRNA. (F) 1000 pg of AtobNGN mRNA. (G) Schematic representation of NGNH2ATO and ATOH2NGN. (H) Quantitative analysis of proneural activity of misexpressed ATO (blue), NGN1 (dark pink), NGNH2ATO (light pink). (I) N-tubulin stained Xenopus embryo at stage 19, injected with 1000 pg of AtoH2NGN mRNA into one cell of two-cell stage embryos.

View larger version (39K): [in a new window]   Fig. 3. Mouse NGN1 interacts with DA and Notch, but fails to induce SENS expression. (A) Quantitative analysis of the number of ectopic bristles per fly induced by expressing NGN1 in wild-type, da+/–, Notch+/– or E(spl)+/– background, or co-expression with constitutively active Notch, or the members of E(spl) complex, m8 or m. With the exception of the E(spl)+/– background, the effects of NGN1 expression in all backgrounds are significantly different from its effects in a wild-type background (P<0.001). (Inset) Autoradiograph of SDS-PAGE gels from co-immunoprecipitation using anti-Myc antibodies of 35S-labeled ATO, MATH1 and NGN1 in the presence and absence of Myc tagged DA. (B) The expression pattern of SENS in cs L3 wing disc, stained with anti-SENS (green). (C) A uasato; dppGal4/+ wing disc, stained with anti-ATO (red) and anti-SENS (green). (D) A uasngn1,dppGal4/TM6 wing disc, stained with ant-NGN1 (red) and anti-SENS (green). (E) A N8/+; uasngn1,dppGal4/+ wing disc, stained with anti-NGN1 (red) and anti-SENS (green). (F) Quantitative analysis of the number of SENS positive cells in CS (wild type), uasMath1/+;dppGal4/+, uasngn1,dppGal4/+ and N8/+ and N8/+;;uasngn1,dppGal4/+ L3 wing discs (n=5).

View larger version (76K): [in a new window]   Fig. 5. NGNbATO and ATObNGN have reversed interactions with Zn-finger proteins. (A-C) uasngnbato/+; dppGal4/+ L3 wing disc stained with (A) anti-NGN1 (red) and (B) anti-SENS (green). (C) A merged image of A and B shows that misexpression of NGNbATO induces SENS. (D) Quantitative analysis of the SENS effect on NGNbATO. (E-H) Injected Xenopus embryos at stage 19, stained with N-tubulin. (E) 100 pg AtobNGN. (F) 100 pg AtobNGN and 250 pg X-MyT1. (G) 100 pg AtoH2-NGN. (H) 100 pg of AtoH2-NGN and 250 pg X-MyT1 mRNA.

View larger version (36K): [in a new window]   Fig. 6. The putative function of ATO proteins and NGN proteins during neuronal lineage development in Drosophila and vertebrates. (A) Both ATO proteins and NGN proteins may be specifying early neural progenitors (NPCs) in flies and vertebrates, respectively, using divergent mechanisms. N and G are neuronal and glial precursors, respectively. (B) In vertebrates, NGN proteins may specify neuronal, rather than neural, precursor cells. In this model, it is not known which genes specify neural precursor cells. (C) ATO proteins and NGN proteins use different genetic pathways to regulate Notch signalling and neural and/or neuronal precursors. X and Y refer to different unknown factors that mediate the synergy between ATOs and SENS on the one hand, and NGNs and MyT1 on the other.