Dramatic Co-Activation of WWOX/WOX1 with CREB and NF-κB in Delayed Loss of Small Dorsal Root Ganglion Neurons upon Sciatic Nerve Transection in Rats

Abstract

BackgroundTumor suppressor WOX1 (also named WWOX or FOR) is known to participate in neuronal apoptosis in vivo. Here, we investigated the functional role of WOX1 and transcription factors in the delayed loss of axotomized neurons in dorsal root ganglia (DRG) in rats.Methodology/Principal FindingsSciatic nerve transection in rats rapidly induced JNK1 activation and upregulation of mRNA and protein expression of WOX1 in the injured DRG neurons in 30 min. Accumulation of p-WOX1, p-JNK1, p-CREB, p-c-Jun, NF-κB and ATF3 in the nuclei of injured neurons took place within hours or the first week of injury. At the second month, dramatic nuclear accumulation of WOX1 with CREB (>65% neurons) and NF-κB (40–65%) occurred essentially in small DRG neurons, followed by apoptosis at later months. WOX1 physically interacted with CREB most strongly in the nuclei as determined by FRET analysis. Immunoelectron microscopy revealed the complex formation of p-WOX1 with p-CREB and p-c-Jun in vivo. WOX1 blocked the prosurvival CREB-, CRE-, and AP-1-mediated promoter activation in vitro. In contrast, WOX1 enhanced promoter activation governed by c-Jun, Elk-1 and NF-κB. WOX1 directly activated NF-κB-regulated promoter via its WW domains. Smad4 and p53 were not involved in the delayed loss of small DRG neurons.Conclusions/SignificanceRapid activation of JNK1 and WOX1 during the acute phase of injury is critical in determining neuronal survival or death, as both proteins functionally antagonize. In the chronic phase, concurrent activation of WOX1, CREB, and NF-κB occurs in small neurons just prior to apoptosis. Likely in vivo interactions are: 1) WOX1 inhibits the neuroprotective CREB, which leads to eventual neuronal death, and 2) WOX1 enhances NF-κB promoter activation (which turns to be proapoptotic). Evidently, WOX1 is the potential target for drug intervention in mitigating symptoms associated with neuronal injury.

Introduction to a Thematic Issue for WWOX

“…5 Rapid accumulation of WWOX has been shown in the apoptotic nuclei of damaged neurons when rats are subjected to (1) prolonged exposure of eyes to constant light, 6 (2) exposure to dopaminergic neurotoxin 1-methyl-4-phenyl-pyridinium (MPPþ) to develop Parkinson's disease (PD)-like symptoms in the striatum of the brain, 14 or (3) dissection of sciatic nerve. 15 WWOX physically interacts with proteins associated with Alzheimer's diseases (AD). 13 Proteins of this category include TRAPPC6A, 16 TIAF1, 17,18 Tau, 7 GSK-3b, 19 JNK1, 7,20 ERK, 7,21 and many other unidentified proteins.…”

Regulation of cell signaling and apoptosis by tumor suppressor WWOX

“…49 After sciatic nerve transection in rats, TCF NF-kB, ATF3, and phosphorylated c-Jun, and CREB rapidly accumulate in the nuclei of injured neurons. 38 Wwox is also upregulated in the dorsal root ganglion (DRG) neurons within hours. 38 Phosphorylated Wwox protein blocks the prosurvival CREB-and AP-1-mediated promoter activation, indicating concurrent activation of Wwox with TCF for regulating apoptosis of small DRG neurons upon neuronal injury in rats.…”

WW Domain-Containing Oxidoreductase is a Potential Receptor for Sex Steroid Hormones

“…For example, WWOX/WOX1 controls the activation of transcription factors, including p53 (Lo et al, 2008;Chang et al, 2001Chang et al, , 2003aChang et al, , 2003bChang et al, , 2005aChang et al, , 2005bLai et al, 2005), p73 (Aqeilan et al, 2004a), AP2 (Aqeilan et al, 2004b), c-Jun (Gaudio et al, 2006;Li et al, 2009), and CREB . By immunoelectron microscopy, FRET (Förster resonance energy transfer) and co-immunoprecipitation, we have revealed the complex formation of the Tyr33-phosphorylated or activated WOX1 with p-CREB and p-c-Jun in vivo .…”

“…Tyr33 phosphorylation and accumulation in the mitochondria and nuclei Lo et al, 2008;Li et al, 2009). Tyr287 in WWOX/WOX1 can undergo phosphorylation by activated tyrosine kinase 1 (Ack1) for polyubiquitination and protein degradation in prostate cancer cells (Mahajan et al, 2005).…”

“…WWOX/WOX1 receives and integrates signals from cell surface by undergoing Tyr33-phosphorylation and relocation to the nuclei in vitro and in vivo review). Nuclear WWOX may either enhance or inhibit the promoter activities regulated by SMAD, NF-B, c-JUN, CREB and other transcription factors (Gaudio et al, 2006;Li et al, 2009;Chang et al, 2010). By immunoelectron microscopy, WWOX/WOX1 can exist alone at the membrane/cytosleleton …”