Characterisation of a new regulator of BDNF signalling, Sprouty3, involved in axonal morphogenesis in vivo.
During development, many organs, including the kidney, lung and mammary gland, need to branch in a regulated manner to be functional. Multicellular branching involves changes in cell shape, proliferation and migration. Axonal branching, however, is a unicellular process that is mediated by changes in cell shape alone and as such appears very different to multicellular branching. Sprouty (Spry) family members are well-characterised negative regulators of Receptor tyrosine kinase (RTK) signalling. Knockout of Spry1, 2 and 4 in mouse result in branching defects in different organs, indicating an important role of RTK signalling in controlling branching pattern. We report here that Spry3, a previously uncharacterised member of the Spry family plays a role in axonal branching. We found that spry3 is expressed specifically in the trigeminal nerve and in spinal motor and sensory neurons in a Brain-derived neurotrophin factor (BDNF)-dependent manner. Knockdown of Spry3 expression causes an excess of axonal branching in spinal cord motoneurons in vivo. Furthermore, Spry3 inhibits the ability of BDNF to induce filopodia in Xenopus spinal cord neurons. Biochemically, we show that Spry3 represses calcium release downstream of BDNF signalling. Altogether, we have found that Spry3 plays an important role in the regulation of axonal branching of motoneurons in vivo, raising the possibility of unexpected conservation in the involvement of intracellular regulators of RTK signalling in multicellular and unicellular branching.
Faculty of Life Sciences, Michael Smith Building, University of Manchester, Oxford Road, Manchester, UK.
Niki
N
Panagiotaki
Federico
F
Dajas-Bailador
Enrique
E
Amaya
Nancy
N
Papalopulu
Karel
K
Dorey
D000818:Animals; D001369:Axons / Q000201:enzymology / Q000378:metabolism*; D001483:Base Sequence; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D020013:Calcium Signaling; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D010802:Phylogeny; D011554:Pseudopodia / Q000378:metabolism; D020813:Receptor, trkB / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus / Q000196:embryology / Q000235:genetics; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*
D019208:Brain-Derived Neurotrophic Factor; D047908:Intracellular Signaling Peptides and Proteins; C554200:Spry3 protein, Xenopus; D029867:Xenopus Proteins; C554199:sprouty3 protein, mouse; D020813:Receptor, trkB; D048049:Extracellular Signal-Regulated MAP Kinases