The Midline Protein Regulates Axon Guidance by Blocking the Reiteration of Neuroblast Rows within the Drosophila Ventral Nerve Cord

Mary Ann Manavalan, Ivana Gaziova, Krishna Moorthi Bhat

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Guiding axon growth cones towards their targets is a fundamental process that occurs in a developing nervous system. Several major signaling systems are involved in axon-guidance, and disruption of these systems causes axon-guidance defects. However, the specific role of the environment in which axons navigate in regulating axon-guidance has not been examined in detail. In Drosophila, the ventral nerve cord is divided into segments, and half-segments and the precursor neuroblasts are formed in rows and columns in individual half-segments. The row-wise expression of segment-polarity genes within the neuroectoderm provides the initial row-wise identity to neuroblasts. Here, we show that in embryos mutant for the gene midline, which encodes a T-box DNA binding protein, row-2 neuroblasts and their neuroectoderm adopt a row-5 identity. This reiteration of row-5 ultimately creates a non-permissive zone or a barrier, which prevents the extension of interneuronal longitudinal tracts along their normal anterior-posterior path. While we do not know the nature of the barrier, the axon tracts either stall when they reach this region or project across the midline or towards the periphery along this zone. Previously, we had shown that midline ensures ancestry-dependent fate specification in a neuronal lineage. These results provide the molecular basis for the axon guidance defects in midline mutants and the significance of proper specification of the environment to axon-guidance. These results also reveal the importance of segmental polarity in guiding axons from one segment to the next, and a link between establishment of broad segmental identity and axon guidance.

Original languageEnglish (US)
Article numbere1004050
JournalPLoS Genetics
Volume9
Issue number12
DOIs
StatePublished - 2013

Fingerprint

ventral nerve cord
axons
Drosophila
defect
protein
Axons
gene
nervous system
ancestry
Neural Plate
embryo
Proteins
proteins
DNA
Growth Cones
DNA-Binding Proteins
Nervous System
Genes
mutant
Axon Guidance

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology
  • Ecology, Evolution, Behavior and Systematics
  • Cancer Research
  • Genetics(clinical)

Cite this

The Midline Protein Regulates Axon Guidance by Blocking the Reiteration of Neuroblast Rows within the Drosophila Ventral Nerve Cord. / Manavalan, Mary Ann; Gaziova, Ivana; Bhat, Krishna Moorthi.

In: PLoS Genetics, Vol. 9, No. 12, e1004050, 2013.

Research output: Contribution to journalArticle

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