Spineless provides a little backbone for dendritic morphogenesis.
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Biomedical subjects
Jay E Brenman
Publications and source records attributed to Jay E Brenman.
The coiled-coil protein shrub controls neuronal morphogenesis in Drosophila.
The diversity of neuronal cells, especially in the size and shape of their dendritic and axonal arborizations, is a striking feature of the mature nervous system. Dendritic branching is a complex process, and the underlying signaling mechanisms remain to be further defined at the mechanistic level. Here we report the identification of shrub mutations that increased dendritic branching. Single-cell clones of shrub mutant dendritic arborization (DA) sensory neurons in Drosophila larvae showed ectopic dendritic and axonal branching, indicating a cell-autonomous function for shrub in neuronal morphogenesis. shrub encodes an evolutionarily conserved coiled-coil protein homologous to the yeast protein Snf7, a key component in the ESCRT-III (endosomal sorting complex required for transport) complex that is involved in the formation of endosomal compartments known as multivesicular bodies (MVBs). We found that mouse orthologs could substitute for Shrub in mutant Drosophila embryos and that loss of Shrub function caused abnormal distribution of several early or late endosomal markers in DA sensory neurons. Our findings demonstrate that the novel coiled-coil protein Shrub functions in the endosomal pathway and plays an essential role in neuronal morphogenesis.
Animals↗
A novel forward genetic screen for identifying mutations affecting larval neuronal dendrite development in Drosophila melanogaster.
Vertebrate and invertebrate dendrites are information-processing compartments that can be found on both central and peripheral neurons. Elucidating the molecular underpinnings of information processing in the nervous system ultimately requires an understanding of the genetic pathways that regulate dendrite formation and maintenance. Despite the importance of dendrite development, few forward genetic approaches have been used to analyze the latest stages of dendrite development, including the formation of F-actin-rich dendritic filopodia or dendritic spines. We developed a forward genetic screen utilizing transgenic Drosophila second instar larvae expressing an actin, green fluorescent protein (GFP) fusion protein (actin::GFP) in subsets of sensory neurons. Utilizing this fluorescent transgenic reporter, we conducted a forward genetic screen of >4000 mutagenized chromosomes bearing lethal mutations that affected multiple aspects of larval dendrite development. We isolated 13 mutations on the X and second chromosomes composing 11 complementation groups affecting dendrite outgrowth/branching, dendritic filopodia formation, or actin::GFP localization within dendrites in vivo. In a fortuitous observation, we observed that the structure of dendritic arborization (da) neuron dendritic filopodia changes in response to a changing environment.
Animals↗
Calcium/calmodulin-dependent protein kinase II alters structural plasticity and cytoskeletal dynamics in Drosophila.
Drosophila dendritic arborization (da) neurons contain subclasses of neurons with distinct dendritic morphologies. We investigated calcium/calmodulin-dependent protein kinase II (CaMKII) regulation of dendritic structure and dynamics in vivo using optically transparent Drosophila larvae. CaMKII increases the dynamic nature and formation of dendritic filopodia throughout larval development but only affects neurons that normally contain dendritic filopodia. In parallel, we examined the effects of Rac1 activity on dendritic structure to explore signaling specificity. In contrast to CaMKII activity, Rac1 does not alter filopodia stability but instead causes de novo filopodia formation on all da neurons. Although both mediators increase cytoskeletal turnover, measured by fluorescence recovery after photobleaching experiments, only CaMKII increases the dynamic nature of dendritic filopodia. CaMKII signaling thus appears to use mechanisms and machinery distinct from Rac1 signaling. This study illustrates a molecular means of uncoupling cytoskeletal regulation from morphological regulation. Our results suggest that Drosophila dendritic filopodia may share some cytoskeletal regulatory mechanisms with mammalian dendritic filopodia. Furthermore, general dendrite cytoskeletal compartmentalization is conserved in multipolar neurons.
Actins↗