ProBDNF Collapses Neurite Outgrowth of Primary Neurons by Activating RhoA

Abstract

BackgroundNeurons extend their dendrites and axons to build functional neural circuits, which are regulated by both positive and negative signals during development. Brain-derived neurotrophic factor (BDNF) is a positive regulator for neurite outgrowth and neuronal survival but the functions of its precursor (proBDNF) are less characterized.Methodology/Principal FindingsHere we show that proBDNF collapses neurite outgrowth in murine dorsal root ganglion (DRG) neurons and cortical neurons by activating RhoA via the p75 neurotrophin receptor (p75NTR). We demonstrated that the receptor proteins for proBDNF, p75NTR and sortilin, were highly expressed in cultured DRG or cortical neurons. ProBDNF caused a dramatic neurite collapse in a dose-dependent manner and this effect was about 500 fold more potent than myelin-associated glycoprotein. Neutralization of endogenous proBDNF by using antibodies enhanced neurite outgrowth in vitro and in vivo, but this effect was lost in p75NTR−/− mice. The neurite outgrowth of cortical neurons from p75NTR deficient (p75NTR−/−) mice was insensitive to proBDNF. There was a time-dependent reduction of length and number of filopodia in response to proBDNF which was accompanied with a polarized RhoA activation in growth cones. Moreover, proBDNF treatment of cortical neurons resulted in a time-dependent activation of RhoA but not Cdc42 and the effect was absent in p75NTR−/− neurons. Rho kinase (ROCK) and the collapsin response mediator protein-2 (CRMP-2) were also involved in the proBDNF action.ConclusionsproBDNF has an opposing role in neurite outgrowth to that of mature BDNF. Our observations suggest that proBDNF collapses neurites outgrowth and filopodial growth cones by activating RhoA through the p75NTR signaling pathway.

ProBDNF Signaling Regulates Depression-Like Behaviors in Rodents under Chronic Stress

“…Our previous study showed that the neurite outgrowth of dorsal root ganglion neurons in vitro is inhibited upon treatment with proBDNF, but enhanced upon treatment with anti-proBDNF (Sun et al, 2012). As this anti-proBDNF antibody can neutralize the biological activities of proBDNF in neurons (Fan et al, 2008;Sun et al, 2012;Xu et al, 2011), we wished to establish whether anti-proBDNF treatment can reverse the behavioral and pathological impairments in rats caused by chronic stress.…”

“…As this anti-proBDNF antibody can neutralize the biological activities of proBDNF in neurons (Fan et al, 2008;Sun et al, 2012;Xu et al, 2011), we wished to establish whether anti-proBDNF treatment can reverse the behavioral and pathological impairments in rats caused by chronic stress. The present study showed that i.c.v.…”

“…As the precursor form of BDNF, proBDNF has been found to play an opposing role to BDNF in regulating neuronal activity (Sun et al, 2012;Woo et al, 2005;Xu et al, 2011). It is well established that BDNF regulates neuronal survival via activation of a membrane receptor, TrkB, whereas proBDNF regulates neuronal death via activating membrane receptor p75 NTR -mediated apoptotic signaling that requires another membrane receptor called sortilin (Lee et al, 2001;Nykjaer et al, 2004;Teng et al, 2005).…”

Mature brain-derived neurotrophic factor and its receptor TrkB are upregulated in human glioma tissues

“…ProBDNF is synthesized and subsequently cleaved, either intracellularly, by prohormone convertases and furin, or extracellularly, by plasmin and matrix metalloproteinases (MMPs), to generate mature BDNF (6,7). Mature BDNF and proBDNF exert opposing effects through two different transmembrane receptor signaling systems, consisting of tyrosine receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) to modulate cell apoptosis (8)(9)(10), long-term depression (11) and synaptic plasticity (12)(13)(14)(15).…”

Unravelling the Mechanism of TrkA-Induced Cell Death by Macropinocytosis in Medulloblastoma Daoy Cells

“…Thus, we considered whether activation of RhoA, which is known to directly affect F-actin reorganization, was activated by NGF in Daoy-TrkA cells, whether it was localized to the macropinosome membranes, and whether it was essential to drive macropinocytosis. In this respect, RhoA activation has been shown to be associated with both neurite/dendritic extension and retraction in the nervous system (40,(65)(66)(67)(68)(69). We examined the kinetics of NGF-induced activation of RhoA in Daoy-TrkA cells using a GST fusion protein containing the Rho binding domain of rhotekin and observed RhoA activation as early as 10 min in response to NGF and peak activation at 6 h, and while the abundance of RhoA decreased by 12 to 24 h, the remaining molecules were still active (Fig.…”