Genetics. Published Articles Ahead of Print: April 28, 2006, Copyright © 2006
doi:10.1534/genetics.106.057893


A more recent version of this article appeared on July 1, 2006.

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Glial and Neuronal Functions of the Drosophila Homolog of the Human SWI/SNF Gene, ATR-X (DATR-X), and the jing Zinc Finger Gene Specify the Lateral Positioning of Longitudinal Glia and Axons

Margaret J Sonnenfeld 1*

1 University of Ottawa

* To whom correspondence should be addressed. E-mail: xsun100{at}uottawa.ca.

Submitted on March 3, 2006
Revised on April 4, 2006
Accepted on 27 April 2006


Abstract

Neuronal-glial communication is essential for constructing the orthogonal axon scaffold in the developing Drosophila central nervous system (CNS). Longitudinal glia (LG) guide extending commissural and longitudinal axons while pioneer and commissural neurons maintain glial survival and positioning. However, the transcriptional regulatory mechanisms controlling these processes are not known. Previous studies showed that the midline function of the jing C2H2-type zinc finger transcription factor was only partially required for axon scaffold formation in the Drosophila CNS. We therefore screened for gain-of-function enhancers of jing gain-of-function in the eye and identified the Drosophila homolog of the disease gene of human {alpha}-thalassemia/mental retardation X-linked (ATR-X), as well as other genes with potential roles in gene expression, translation, synaptic transmission and cell cycle. jing and DATR-X reporter genes are expressed in both CNS neurons and glia including the longitudinal glia. Co-expression of jing and DATR-X in embryonic neurons synergistically affects longitudinal connective formation. During embryogenesis, jing and DATR-X have autonomous and non-autonomous roles in the lateral positioning of LG, neurons and longitudinal axons as shown by cell-specific knock-down of gene expression. jing and DATR-X are also required autonomously for glial survival. jing and DATR-X mutations show synergistic effects during longitudinal axon formation suggesting they are functionally related. These observations support a model in which downstream gene expression controlled by a potential DATR-X-Jing complex facilitates cellular positioning and axon guidance ultimately allowing for proper connectivity in the developing Drosophila CNS.

Key Words: DATR-X, X-linked mental retardation, genetic enhancer screen, jing, transcriptional regulation