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Linda L. Restifo

Professor of Neurobiology and Neurology

M.D., 1984, University of Pennsylvania School of Medicine
Ph.D. 1986, University of Pennsylvania


Office: Gould-Simpson Bldg. Rm. 423
Email: llr@neurobio.arizona.edu
Phone: (520) 621-9821
Fax: (520) 621-8282
Restifo lab group

The Restifo Lab in the News

Postdoc Positions available through the PERT training program
 
Genetics of brain development and neuronal plasticity; genetics of mental retardation;
drug discovery for developmental brain disorders


My overarching interest is in the genetics of brain development, ranging from the control of large-scale morphogenetic movements to the remodeling of individual neurons. We use the fruit fly model system, Drosophila melanogaster, in part because of its phylogenetic similarities to mammals. In particular, we are using fruit flies to understand human developmental brain disorders, such as mental retardation and autism, and as a drug-discovery tool. Our methods include genetic manipulations, primary neuron cell culture, immunostaining and confocal microscopy, expression profiling (with Affymetrix microarrays), bioinformatics, and software development for neuron-image analysis.

In order to study genetic pathways that control brain morphogenesis and neuronal plasticity, we focus on the metamorphosis portion of development because the nervous system undergoes dramatic changes, including neuronal remodeling. These changes are under the control of a steroid hormone, 20-hydroxyecdysone (20E), whose receptor subunits are members of the nuclear receptor superfamily. At the cellular level, steroid hormone-induced changes in neuronal structure and function are very similar in mammals and insects.

Many of our studies deal with a fascinating brain region, the mushroom bodies, which are remodeled during metamorphosis and which mediate complex adult behaviors, including some forms of learning and memory. We used dissociated cell culture methods to demonstrate that 20E promotes neurite outgrowth of mushroom body neurons harvested early in the metamorphic interval. We also found a number of neuronal morphology phenotypes in vitro, which suggested that cell culture could provide a sensitive assay system for identifying neuronal defects (see below).

We determined that Broad Complex transcription factors play a pivotal role in mediating 20E-regulated nervous system metamorphosis. This family of BTB-zinc-finger proteins (BRC-Z1 through -Z4) is generated by alternative splicing of transcripts from a large gene directly induced by 20E in the CNS and other tissues. Transgenic-rescue and spatial expression studies support a model of BRC function in coordinating cell-cell interactions that underlie central nervous system morphogenetic movements.

Hundreds of human genes can mutate to a mental retardation (MR) phenotype, either in isolation or as part of a syndrome. We used bioinformatics methods to show that 75% of human MR genes have a candidate functional ortholog in Drosophila. To date, four of the Drosophila genes have been shown by others to have learning or memory phenotypes, and we predict that this will be true for many more of them. We showed that mutants of Drosophila fragile X mental retardation 1 (dfmr1) have defects in mushroom body development during metamorphosis. A major new initiative uses mushroom body cell culture methods to search for neuronal phenotypes of MR gene mutants in vitro. Our long-term goal is to use the Drosophila system as a stepping stone for discovery of drugs that will benefit human MR patients.


Selected Recent Publications  

Spokony RF, Restifo, LL. Jul 2007. Anciently duplicated Broad Complex exons have distinct temporal functions during tissue morphogenesis. Development Genes and Evolution, 217:499-513

Narro ML, Yang F, Kraft R, Wenk C, Efrat A, Restifo LL. Mar 2007. NeuronMetrics: software for rapid semi-automated processing of cultured-neuron images. Brain Research, 1138:57-75

Kraft R, Escobar MM, Narro ML, Kurtis JL, Efrat A, Barnard K, Restifo LL. Aug 2006. Phenotypes of Drosophila brain neurons in primary culture reveal a role for fascin in neurite shape and trajectory. J Neurosci, 26:8734-47

Warren JT, Yerushalmi Y, Shimell MJ, O'Connor MB, Restifo LL, Gilbert LI. Feb 2006. Discrete pulses of molting hormone, 20-hydroxyecdysone, during late larval development of Drosophila melanogaster: correlations with changes in gene activity. Dev Dyn, 235:315-26

Wilson TG, Yerushalmi Y, Donnell DM, Restifo LL. Jan 2006. Interaction Between Hormonal Signaling Pathways in Drosophila melanogaster as Revealed by Genetic Interaction Between Methoprene-tolerant and Broad-Complex. Genetics, 172:253-64

Consoulas C, Levine RB, Restifo LL. May 2005. The steroid hormone-regulated gene Broad Complex is required for dendritic growth of motoneurons during metamorphosis of Drosophila. J Comp Neurol, 485:321-37

Restifo LL. Jan 2005. Mental retardation genes in drosophila: New approaches to understanding and treating developmental brain disorders. Ment Retard Dev Disabil Res Rev, 11:286-94

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