title: Reactive oxygen species are involved in BMP-induced dendritic growth in cultured rat sympathetic neurons.
abstract: Previous studies have shown that bone morphogenetic proteins (BMPs) promote dendritic growth in sympathetic neurons; however, the downstream signaling molecules that mediate the dendrite promoting activity of BMPs are not well characterized. Here we test the hypothesis that reactive oxygen species (ROS)-mediated signaling links BMP receptor activation to dendritic growth. In cultured rat sympathetic neurons, exposure to any of the three mechanistically distinct antioxidants, diphenylene iodinium (DPI), nordihydroguaiaretic acid (NGA) or desferroxamine (DFO), blocked de novo BMP-induced dendritic growth. Addition of DPI to cultures previously induced with BMP to extend dendrites caused dendritic retraction while DFO and NGA prevented further growth of dendrites. The inhibition of the dendrite promoting activity of BMPs by antioxidants was concentration-dependent and occurred without altering axonal growth or neuronal cell survival. Antioxidant treatment did not block BMP activation of SMAD 1,5 as determined by nuclear localization of these SMADs. While BMP treatment did not cause a detectable increase in intracellular ROS in cultured sympathetic neurons as assessed using fluorescent indicator dyes, BMP treatment increased the oxygen consumption rate in cultured sympathetic neurons as determined using the Seahorse XF24 Analyzer, suggesting increased mitochondrial activity. In addition, BMPs upregulated expression of NADPH oxidase 2 (NOX2) and either pharmacological inhibition or siRNA knockdown of NOX2 significantly decreased BMP-7 induced dendritic growth. Collectively, these data support the hypothesis that ROS are involved in the downstream signaling events that mediate BMP7-induced dendritic growth in sympathetic neurons, and suggest that ROS-mediated signaling positively modulates dendritic complexity in peripheral neurons.
authors.affiliation: Department of Biology, Saint Mary's College of California, Moraga, CA, USA. Electronic address: vc5@stmarys-ca.edu.
authors.forename: Vidya
authors.initials: V
authors.lastname: Chandrasekaran
authors.affiliation: Department of Biology, Saint Mary's College of California, Moraga, CA, USA.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Lea
authors.affiliation: Department of Biology, Saint Mary's College of California, Moraga, CA, USA.
authors.forename: Jose Carlo
authors.initials: JC
authors.lastname: Sosa
authors.affiliation: Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Higgins
authors.affiliation: Department of Molecular Biosciences, University of California, Davis, CA, USA.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Lein
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002478:Cells, Cultured; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D055495:Neurogenesis; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D017783:Superior Cervical Ganglion / Q000166:cytology / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; D051785:Smad Proteins; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D010100:Oxygen
keywords: Antioxidants; Bone morphogenetic proteins; Dendrites; Free radicals; Reactive oxygen species; Sympathetic neurons