Biology subjects

Marquilly, C.

Publications and source records attributed to Marquilly, C..

3 recordsLinked to original sources

bioRxiv2023

Respective contribution of Appl to mushroom body axon growth and long-term memory in Drosophila

The Amyloid Precursor Protein (APP) is associated with Alzheimers disease. Appl is the single Drosophila APP ortholog and is expressed in all neurons throughout development. Appl was previously shown to cell-autonomously modulate axon outgrowth in the mushroom bodies (MBs), the fly olfactory memory center. However, we found that Appld, the only reported null allele, affects the normal function of vnd, the gene just proximal to Appl. To decipher developmental defects specifically due to a loss of only Appl function, we generated a precise Appl null allele (ApplC2.1) by CRISPR/Cas9 genomic engineering. With ApplC2.1, we confirmed the partial requirement for Appl in MB axon outgrowth. We also produced new CRISPR vnd alleles removing either vnd-B or vnd-A function. We report here that vnd is also required for MB {beta}-branch axon outgrowth and to a much greater extent than Appl itself. Moreover, vnd is expressed in neurons close to, but not within, the MB during development and is required non-cell-autonomously for MB axon outgrowth

neuroscience↗

bioRxiv2022

The actin nucleator Spire cooperates with Rab11 to initiate nascent dendrite branches.

Dendrites form arbors whose size, shape and complexity define how neurons cover their receptive territories. Actin dynamics contribute to growth and remodeling of dendrite arbors. Here we examined how Spire, a conserved actin nucleation factor, promotes formation of new branches in vivo. In live imaging of Drosophila class IV dendritic arborization (c4da) neurons, Spire was observed at new sites of branch initiation, where it assembled new actin polymer in a burst just prior to filopodial outgrowth. For dendrite arborization, Spire required intact structural domains to nucleate actin and target the secretory network, and interacted with Rab11 GTPase, a key regulator of recycling endosomes. Together, these findings support a model in which Spire cooperates with Rab11 to promote new dendrite branches by linking localized actin dynamics with intracellular trafficking of endosomes that deliver lipids and cargoes to fuel protrusive outgrowth of nascent dendrites.

neuroscience↗

bioRxiv2019

HTT is a repressor of ABL activity required for APP induced axonal growth

ABL tyrosine kinase activity controls several aspects of development including axon patterning. Amyloid precursor protein (APP) is linked to Alzheimers disease and previous work established that ABL is a downstream effector in an Appl, the Drosophila App ortholog, signaling pathway which modulates axon outgrowth in the mushroom bodies (MBs), the fly memory center. Here we show that Abl is required for the MB neuron axonal growth. Importantly, both Abl overexpression and lack of expression produce a similar phenotype in the MBs indicating the necessity of tightly regulating ABL activity. We find that the fly huntingtin protein (HTT), the homolog of the protein involved in Huntingtons disease, behaves genetically as a repressor of ABL activity. Supporting this, FRET-based measurements of in vivo ABL activity in the MBs reveal a clear increase in its activity when HTT levels are reduced. Thus, in addition to its many other reported roles, HTT acts as a negative regulator of ABL activity, at least in the MBs, to maintain its appropriate physiological levels necessary for axon growth.

neuroscience↗