Endophilin A2 controls touch and mechanical allodynia via kinesin-mediated Piezo2 trafficking.

BACKGROUND: Tactile and mechanical pain are crucial to our interaction with the environment, yet the underpinning molecular mechanism is still elusive. Endophilin A2 (EndoA2) is an evolutionarily conserved protein that is documented in the endocytosis pathway. However, the role of EndoA2 in the regulation of mechanical sensitivity and its underlying mechanisms are currently unclear. METHODS: Male and female C57BL/6 mice (8-12 weeks) and male cynomolgus monkeys (7-10 years old) were used in our experiments. Nerve injury-, inflammatory-, and chemotherapy-induced pathological pain models were established for this study. Behavioral tests of touch, mechanical pain, heat pain, and cold pain were performed in mice and nonhuman primates. Western blotting, immunostaining, co-immunoprecipitation, proximity ligation and patch-clamp recordings were performed to gain insight into the mechanisms. RESULTS: The results showed that EndoA2 was primarily distributed in neurofilament-200-positive (NF200+) medium-to-large diameter dorsal root ganglion (DRG) neurons of mice and humans. Loss of EndoA2 in mouse NF200+ DRG neurons selectively impaired the tactile and mechanical allodynia. Furthermore, EndoA2 interacted with the mechanically sensitive ion channel Piezo2 and promoted the membrane trafficking of Piezo2 in DRG neurons. Moreover, as an adaptor protein, EndoA2 also bound to kinesin family member 5B (KIF5B), which was involved in the EndoA2-mediated membrane trafficking process of Piezo2. Loss of EndoA2 in mouse DRG neurons damaged Piezo2-mediated rapidly adapting mechanically activated currents, and re-expression of EndoA2 rescued the MA currents. In addition, interference with EndoA2 also suppressed touch sensitivity and mechanical hypersensitivity in nonhuman primates. CONCLUSIONS: Our data reveal that the KIF5B/EndoA2/Piezo2 complex is essential for Piezo2 trafficking and for sustaining transmission of touch and mechanical hypersensitivity signals. EndoA2 regulates touch and mechanical allodynia via kinesin-mediated Piezo2 trafficking in sensory neurons. Our findings identify a potential new target for the treatment of mechanical pain.

Hen Egg Lysozyme Alleviates Static Mechanical Pain Via NRF1-Parkin-TACAN Signaling Axis in Sensory Neurons.

Mechanical allodynia impinges on the life quality of patients. Hen Egg Lysozyme (HEL) is a substance extracted from eggs that is commonly used to inhibit bacterial activity. The role of HEL in regulating and treating pain is unclear. Here, we find that HEL selectively attenuates static mechanical allodynia of mice induced by complete Freund's adjuvant (CFA), spinal nerve ligation (SNL) and chemotherapeutic agent. RNA-seq screening reveals that CFA significantly reduces the expression of Parkin in dorsal root ganglion (DRG) neurons of mice, while pre-administration of HEL increases the expression of Parkin and remits the static mechanical allodynia induced by Parkin-siRNA. Moreover, HEL increases the interaction between nuclear respiratory factor 1 (NRF1) and histone acetyltransferase P300 and then enhances the NRF1 mediated histone acetylation in prkn promoter region in DRGs of mice. Further, Parkin interacts with mechanotransducing ion channel TACAN (Tmem120a) and knockdown of Parkin significantly increases the membrane trafficking of TACAN in sensory neurons of mice. While pre-administration of HEL inhibits the increased membrane trafficking of TACAN in sensory neurons of mice induced by Parkin-siRNA. In addition, pre-given of HEL also significantly attenuates the static mechanical allodynia induced by overexpression of TACAN in mice, and the effect of HEL can be blocked by Parkin-siRNA. This indicates that HEL increases the expression of Parkin through epigenetic mechanisms and then decreases TACAN membrane trafficking in sensory neurons to relieve static mechanical hypersensitivity. Therefore, we reveal a novel function of HEL, which is a potential substance for the treatment of static mechanical pain.

ATF4 selectively regulates heat nociception and contributes to kinesin-mediated TRPM3 trafficking.

Effective treatments for patients suffering from heat hypersensitivity are lacking, mostly due to our limited understanding of the pathogenic mechanisms underlying this disorder. In the nervous system, activating transcription factor 4 (ATF4) is involved in the regulation of synaptic plasticity and memory formation. Here, we show that ATF4 plays an important role in heat nociception. Indeed, loss of ATF4 in mouse dorsal root ganglion (DRG) neurons selectively impairs heat sensitivity. Mechanistically, we show that ATF4 interacts with transient receptor potential cation channel subfamily M member-3 (TRPM3) and mediates the membrane trafficking of TRPM3 in DRG neurons in response to heat. Loss of ATF4 also significantly decreases the current and KIF17-mediated trafficking of TRPM3, suggesting that the KIF17/ATF4/TRPM3 complex is required for the neuronal response to heat stimuli. Our findings unveil the non-transcriptional role of ATF4 in the response to heat stimuli in DRG neurons.

Difference of pain vulnerability in adult and juvenile rodents: the role of SIRT1-mediated ClC-3 trafficking in sensory neurons.

ABSTRACT: Adults are more likely to suffer from chronic pain than minors, and its underlying mechanism remains unclear. SIRT1 an important age-related protein with function of lifespan extension; whether SIRT1 plays a role in the different pain vulnerability of adult and juvenile remains unclear. Here, we found that the expression level of SIRT1 in dorsal root ganglia (DRG) was related to the pain vulnerability. After nerve injury, the expression of SIRT1 in DRG was decreased in adult rodents whereas increased in juvenile rodents. Differential manipulation of SIRT1 abolished the different pain vulnerability between adult and juvenile rodents. Furthermore, SIRT1 interacted with ClC-3 channel and mediated ClC-3 membrane trafficking and Cl- current in DRG neurons. Differential manipulation of ClC-3 also abolished the difference in pain vulnerability between adult and juvenile rodents. The different anti-inflammatory ability determined the different change trends of SIRT1 and ClC-3 trafficking contributed to the different pain vulnerability in adult and juvenile rodents. In addition, the serum SIRT1 level was negatively correlated with the pain score in patients with chronic pain. These findings revealed the mechanism of the difference in pain vulnerability between adult and juvenile rodents and provided evidence for age-specific treatment of chronic pain.

Foxo1 selectively regulates static mechanical pain by interacting with Nav1.7.

ABSTRACT: Mechanical allodynia is a debilitating condition for millions of patients with chronic pain. Mechanical allodynia can manifest in distinct forms, including brush-evoked dynamic and filament-evoked static allodynia. In the nervous system, the forkhead protein Foxo1 plays a critical role in neuronal structures and functions. However, the role of Foxo1 in the somatosensory signal remains unclear. Here, we found that Foxo1 selectively regulated static mechanical pain. Foxo1 knockdown decreased sensitivity to static mechanical stimuli in normal rats and attenuated static mechanical allodynia in rat models for neuropathic, inflammatory, and chemotherapy pain. Conversely, Foxo1 overexpression selectively enhanced sensitivity to static mechanical stimuli and provoked static mechanical allodynia. Furthermore, Foxo1 interacted with voltage-gated sodium Nav1.7 channels and increased the Nav1.7 current density by accelerating activation rather than by changing the expression of Nav1.7 in dorsal root ganglia neurons. In addition, the serum level of Foxo1 was found to be increased in chronic pain patients and to be positively correlated with the severity of chronic pain. Altogether, our findings suggest that serum Foxo1 level could be used as a biological marker for prediction and diagnosis of chronic pain. Moreover, selective blockade of Foxo1/Nav1.7 interaction may offer a new therapeutic approach in patients with mechanical pain.

Preparation and antagonistic effect of ACE inhibitory peptide from cashew.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitory peptides were found to alleviate acute hepatitis significantly. In this study, we purified and identified ACE inhibitory peptide from cashew to evaluate its protective role on alcohol-induced acute hepatitis in mice. RESULTS: The ACE inhibitory peptides were purified by using consecutive chromatographic techniques. One of these peptides (FETISFK) exhibited the highest ACE inhibition rate (91.04 ± 0.31%). In vivo, the results showed that ACE inhibitory peptide decreased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) caused by alcohol exposure. Moreover, it could increase the activities of superoxide dismutase (SOD) and glutathione (GSH), and decrease the level of malondialdehyde (MDA). It was also found to down-regulate markedly the expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). It could also decrease the expression of ACE, angiotensin II (AngII) and angiotensin II type 1 receptor (AT1 R). CONCLUSION: These findings support the view that the ACE inhibitory peptide alleviated acute hepatitis by down-regulating the ACE-AngII-AT1 R axis, broadening the research approach to prevent acute hepatitis, and providing experimental data for the development and utilization of cashews. © 2019 Society of Chemical Industry.

Puerarin Relieves Paclitaxel-Induced Neuropathic Pain: The Role of Nav1.8 ß1 Subunit of Sensory Neurons.

Currently there is no effective treatment available for clinical patients suffering from neuropathic pain induced by chemotherapy paclitaxel. Puerarin is a major isoflavonoid extracted from the Chinese medical herb kudzu root, which has been used for treatment of cardiovascular disorders and brain injury. Here, we found that puerarin dose-dependently alleviated paclitaxel-induced neuropathic pain. At the same time, puerarin preferentially reduced the excitability and blocked the voltage-gated sodium (Nav) channels of dorsal root ganglion (DRG) neurons from paclitaxel-induced neuropathic pain rats. Furthermore, puerarin was a more potent blocker of tetrodotoxin-resistant (TTX-R) Nav channels than of tetrodotoxin-sensitive (TTX-S) Nav channels in chronic pain rats' DRG neurons. In addition, puerarin had a stronger blocking effect on Nav1.8 channels in DRG neurons of neuropathic pain rats and ß1 subunit siRNA can abolish this selective blocking effect on Nav1.8. Together, these results suggested that puerarin may preferentially block ß1 subunit of Nav1.8 in sensory neurons contributed to its anti-paclitaxel induced neuropathic pain effect.

Immune response mechanism of mouse monocytes/macrophages treated with κ-carrageenan polysaccharide.

This study investigated the function of κ-carrageenan polysaccharide in immune regulation. The immune response of RAW 264.7 cells treated with κ-carrageenan polysaccharide was explored by MTT assay, general morphological observation, neutral red phagocytosis assay, Griess method, fluorescence method, and enzyme-linked immunosorbent assay. In addition, TLR4 blocking experiment and double-fluorescence immunostaining were performed on cells to demonstrate their immune response mechanism. Results show that κ-carrageenan polysaccharide not only promotes cell proliferation but also activates RAW 264.7 cells, thereby improving the cells' phagocytic capability, NO production, and tumor necrosis factor-α (TNF-α) secretion. In addition, the use of TLR4-specific inhibitors can significantly mediate the increased TNF-α secretion induced by κ-carrageenan polysaccharide. The RAW 264.7 cells treated with κ-carrageenan polysaccharide show upregulated TLR4 expression, and the main subunit of NF-κB (p65) is translocated. These results support the immunomodulatory function of κ-carrageenan polysaccharide in RAW 264.7 cells.

Establishment of a new model for culturing rabbit osteoblasts in vitro.

To establish an experimental model for culturing rabbit osteoblasts in vitro, the osteoblasts were isolated from the calvarial bone of a 15-day old rabbit using a method of culturing the bone pieces in a medium after they had been digested by an enzyme for 15 min. The acquired cells were assayed by cell morphology, alkaline phosphatase activity and production of a mineralized matrix. The results showed that the cells had the morphologic characteristics and some biological behaviours of osteoblasts. Based on the primary isolation of osteoblasts from bone and combining digestion with explants, a novel model for culturing rabbit osteoblasts in vitro was established, which is easy, efficient and effective. This model can be used in many studies of osteogenesis mechanisms and bone replacement materials.