ABSTRACT
Fibroblast growth factor-inducible-14 (Fn14), a receptor for tumor necrosis-like weak inducer of apoptosis, is expressed in the neurons of dorsal root ganglion (DRG). Its mRNA is increased in the injured DRG following peripheral nerve injury. Whether this increase contributes to neuropathic pain is unknown. We reported here that peripheral nerve injury caused by spinal nerve ligation (SNL) increased the expression of Fn14 at both protein and mRNA levels in the injured DRG. Blocking this increase attenuated the development of SNL-induced mechanical, thermal, and cold pain hypersensitivities. Conversely, mimicking this increase produced the increases in the levels of phosphorylated extracellular signal-regulated kinase ½ and glial fibrillary acidic protein in ipsilateral dorsal horn and the enhanced responses to mechanical, thermal, and cold stimuli in the absence of SNL. Mechanistically, the increased Fn14 activated the NF-κB pathway through promoting the translocation of p65 into the nucleus of the injured DRG neurons. Our findings suggest that Fn14 may be a potential target for the therapeutic treatment of peripheral neuropathic pain.
Subject(s)
NF-kappa B/metabolism , Neuralgia/metabolism , Sensory Receptor Cells/metabolism , Signal Transduction , TWEAK Receptor/metabolism , Animals , Cells, Cultured , Ganglia, Spinal/metabolism , Ganglia, Spinal/pathology , Ligation , Male , Mice , Microinjections , Neuralgia/pathology , Pain Threshold , Peripheral Nerve Injuries/metabolism , Peripheral Nerve Injuries/pathology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Spinal Nerves/metabolism , Spinal Nerves/pathologyABSTRACT
OBJECTIVE: To study the changes of MAPK and Akt signaling pathways in hearts and placentas of aborted fetuses with congenital heart disease (CHD), and investigate their roles in the pathogenesis of CHD. METHODS: Ten aborted fetuses with severe CHD (CHD group) and 7 gestational age-matched non-cardiac malformation aborted fetuses (control group) were enrolled. Western blot analysis was undertaken to assess the expression of p38, p38alpha, p-p38, MEF2, ERK, p-ERK, Akt, p-Akt(Ser473) and p-Akt(Thr308) in left ventricles and placentas of the fetuses, while semi-quantitative reverse transcription polymerase chain reaction analysis was used to detect the expression of p38alpha isoforms mRNA in hearts. RESULTS: Compared with the heart samples of the control group, the protein expression levels of p38 and its alpha isoform in 4 cases, p-p38 in 6 cases, MEF2 in 2 cases, p-ERK in 8 cases, Akt in 4 cases, p-Akt(Ser473) and p-Akt(Thr308) in 8 cases decreased, while the protein expression levels of p-p38 in 2 cases and p-Akt(Thr308) in 1 case increased. P-p38 protein level in 3 cases and p-ERK protein level in 2 cases decreased in placentas compared with the control group. The changes of protein expression of MAPK and Akt signaling pathway in hearts were not consistent with those in placentas in the CHD group. The expression of p38alpha isoform2 mRNA showed descent tendency in 4 heart samples with CHD, while the expression of other three p38alpha isoforms mRNA was reduced in only 1 sample compared with the control group. CONCLUSIONS: Dysfunction of MAPK and Akt signaling pathways is tissue-specific in aborted fetuses with CHD. The perturbed two signaling pathways in hearts may contribute to the pathogenesis of human CHD.
