title: Abi plays an opposing role to Abl in Drosophila axonogenesis and synaptogenesis.
abstract: Abl tyrosine kinase (Abl) regulates axon guidance by modulating actin dynamics. Abelson interacting protein (Abi), originally identified as a kinase substrate of Abl, also plays a key role in actin dynamics, yet its role with respect to Abl in the developing nervous system remains unclear. Here we show that mutations in abi disrupt axonal patterning in the developing Drosophila central nervous system (CNS). However, reducing abi gene dosage by half substantially rescues Abl mutant phenotypes in pupal lethality, axonal guidance defects and locomotion deficits. Moreover, we show that mutations in Abl increase synaptic growth and spontaneous synaptic transmission frequency at the neuromuscular junction. Double heterozygosity for abi and enabled (ena) also suppresses the synaptic overgrowth phenotypes of Abl mutants, suggesting that Abi acts cooperatively with Ena to antagonize Abl function in synaptogenesis. Intriguingly, overexpressing Abi or Ena alone in cultured cells dramatically redistributed peripheral F-actin to the cytoplasm, with aggregates colocalizing with Abi and/or Ena, and resulted in a reduction in neurite extension. However, co-expressing Abl with Abi or Ena redistributed cytoplasmic F-actin back to the cell periphery and restored bipolar cell morphology. These data suggest that abi and Abl have an antagonistic interaction in Drosophila axonogenesis and synaptogenesis, which possibly occurs through the modulation of F-actin reorganization.
authors.affiliation: Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan.
authors.forename: Tzu-Yang
authors.initials: TY
authors.lastname: Lin
authors.forename: Chiu-Hui
authors.initials: CH
authors.lastname: Huang
authors.forename: Hsiu-Hua
authors.initials: HH
authors.lastname: Kao
authors.forename: Gan-Guang
authors.initials: GG
authors.lastname: Liou
authors.forename: Shih-Rung
authors.initials: SR
authors.lastname: Yeh
authors.forename: Chih-Ming
authors.initials: CM
authors.lastname: Cheng
authors.forename: Mei-Hsin
authors.initials: MH
authors.lastname: Chen
authors.forename: Rong-Long
authors.initials: RL
authors.lastname: Pan
authors.forename: Jyh-Lyh
authors.initials: JL
authors.lastname: Juang
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology* / Q000235:genetics; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism; D010641:Phenotype; D016315:Proto-Oncogene Proteins c-abl / Q000235:genetics / Q000378:metabolism*; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: C121808:Abi protein, Drosophila; D000199:Actins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C092744:ENA-VASP proteins; D008840:Microfilament Proteins; D018377:Neurotransmitter Agents; C449671:SCAR protein, Drosophila; D016315:Proto-Oncogene Proteins c-abl