The Cytidine N-Acetyltransferase NAT10 Participates in Peripheral Nerve Injury-Induced Neuropathic Pain by Stabilizing SYT9 Expression in Primary Sensory Neurons.

RNA N4-acetylcytidine (ac4C) modification is increasingly recognized as an important layer of gene regulation; however, the involvement of ac4C in pain regulation has not been studied. Here, we report that N-acetyltransferase 10 protein (NAT10; the only known ac4C "writer") contributes to the induction and development of neuropathic pain in an ac4C-dependent manner. Peripheral nerve injury increases the levels of NAT10 expression and overall ac4C in injured dorsal root ganglia (DRGs). This upregulation is triggered by the activation of upstream transcription factor 1 (USF1), a transcription factor that binds to the Nat10 promoter. Knock-down or genetic deletion of NAT10 in the DRG abolishes the gain of ac4C sites in Syt9 mRNA and the augmentation of SYT9 protein, resulting in a marked antinociceptive effect in nerve-injured male mice. Conversely, mimicking NAT10 upregulation in the absence of injury evokes the elevation of Syt9 ac4C and SYT9 protein and induces the genesis of neuropathic-pain-like behaviors. These findings demonstrate that USF1-governed NAT10 regulates neuropathic pain by targeting Syt9 ac4C in peripheral nociceptive sensory neurons. Our findings establish NAT10 as a critical endogenous initiator of nociceptive behavior and a promising new target for treating neuropathic pain.SIGNIFICANCE STATEMENT The cytidine N4-acetylcytidine (ac4C), a new epigenetic RNA modification, is crucial for the translation and stability of mRNA, but its role for chronic pain remains unclear. Here, we demonstrate that N-acetyltransferase 10 (NAT10) acts as ac4C N-acetyltransferase and plays an important role in the development and maintenance of neuropathic pain. NAT10 was upregulated via the activation of the transcription factor upstream transcription factor 1 (USF1) in the injured dorsal root ganglion (DRG) after peripheral nerve injury. Since pharmacological or genetic deleting NAT10 in the DRG attenuated the nerve injury-induced nociceptive hypersensitivities partially through suppressing Syt9 mRNA ac4C and stabilizing SYT9 protein level, NAT10 may serve as an effective and novel therapeutic target for neuropathic pain.

Transcription factor ETS proto-oncogene 1 contributes to neuropathic pain by regulating histone deacetylase 1 in primary afferent neurons.

Nerve injury can induce aberrant changes in ion channels, enzymes, and cytokines/chemokines in the dorsal root ganglia (DRGs); these changes are due to or at least partly governed by transcription factors that contribute to the genesis of neuropathic pain. However, the involvement of transcription factors in neuropathic pain is poorly understood. In this study, we report that transcription factor (TF) ETS proto-oncogene 1 (ETS1) is required for the initiation and development of neuropathic pain. Sciatic nerve chronic constrictive injury (CCI, a clinical neuropathic pain model) increases ETS1 expression in the injured male mouse DRG. Blocking this upregulation alleviated CCI-induced mechanical allodynia and thermal hyperalgesia, with no apparent effect on locomotor function. Mimicking this upregulation results in the genesis of nociception hypersensitivity; mechanistically, nerve injury-induced ETS1 upregulation promotes the expression of histone deacetylase 1 (HDAC1, a key initiator of pain) via enhancing its binding activity to the HDAC1 promotor, leading to the elevation of spinal central sensitization, as evidenced by increased expression of p-ERK1/2 and GFAP in the dorsal spinal horn. It appears that the ETS1/HDAC1 axis in DRG may have a critical role in the development and maintenance of neuropathic pain, and ETS1 is a potential therapeutic target in neuropathic pain.

DHX9/DNA-tandem repeat-dependent downregulation of ciRNA-Fmn1 in the dorsal horn is required for neuropathic pain.

Circular RNAs (ciRNAs) are emerging as new players in the regulation of gene expression. However, how ciRNAs are involved in neuropathic pain is poorly understood. Here, we identify the nervous-tissue-specific ciRNA-Fmn1 and report that changes in ciRNA-Fmn1 expression in spinal cord dorsal horn neurons play a key role in neuropathic pain after nerve injury. ciRNA-Fmn1 was significantly downregulated in ipsilateral dorsal horn neurons after peripheral nerve injury, at least in part because of a decrease in DNA helicase 9 (DHX9), which regulates production of ciRNA-Fmn1 by binding to DNA-tandem repeats. Blocking ciRNA-Fmn1 downregulation reversed nerve-injury-induced reductions in both the binding of ciRNA-Fmn1 to the ubiquitin ligase UBR5 and the level of ubiquitination of albumin (ALB), thereby abrogating the nerve-injury-induced increase of ALB expression in the dorsal horn and attenuating the associated pain hypersensitivities. Conversely, mimicking downregulation of ciRNA-Fmn1 in naïve mice reduced the UBR5-controlled ubiquitination of ALB, leading to increased expression of ALB in the dorsal horn and induction of neuropathic-pain-like behaviors in naïve mice. Thus, ciRNA-Fmn1 downregulation caused by changes in binding of DHX9 to DNA-tandem repeats contributes to the genesis of neuropathic pain by negatively modulating UBR5-controlled ALB expression in the dorsal horn.

Branched-Chain Amino Acids Deficiency Promotes Diabetic Neuropathic Pain Through Upregulating LAT1 and Inhibiting Kv1.2 Channel.

Diabetic neuropathic pain (DNP), one of the most common complications of diabetes, is characterized by bilateral symmetrical distal limb pain and substantial morbidity. To compare the differences  is aimed at serum metabolite levels between 81 DNP and 73 T2DM patients without neuropathy and found that the levels of branched-chain amino acids (BCAA) are significantly lower in DNP patients than in T2DM patients. In high-fat diet/low-dose streptozotocin (HFD/STZ)-induced T2DM and leptin receptor-deficient diabetic (db/db) mouse models, it is verified that BCAA deficiency aggravated, whereas BCAA supplementation alleviated DNP symptoms. Mechanistically, using a combination of RNA sequencing of mouse dorsal root ganglion (DRG) tissues and label-free quantitative proteomic analysis of cultured cells, it is found that BCAA deficiency activated the expression of L-type amino acid transporter 1 (LAT1) through ATF4, which is reversed by BCAA supplementation. Abnormally upregulated LAT1 reduced Kv1.2 localization to the cell membrane, and inhibited Kv1.2 channels, thereby increasing neuronal excitability and causing neuropathy. Furthermore, intraperitoneal injection of the LAT1 inhibitor, BCH, alleviated DNP symptoms in mice, confirming that BCAA-deficiency-induced LAT1 activation contributes to the onset of DNP. These findings provide fresh insights into the metabolic differences between DNP and T2DM, and the development of approaches for the management of DNP.

Discovery of a small molecular compound simultaneously targeting RXR and HADC: design, synthesis, molecular docking and bioassay.

Retinoid X receptor (RXR) and Histone deacetylase (HDAC) are considered important targets for anti-cancer therapy due to their crucial roles in genetic or epigenetic regulations of cancer development and progression. Here, we have designed and synthesized a novel compound which targets both RXR and HADC. This dual-targeting agent is derived from bexarotene and suberoylanilide hydroxamic acid (SAHA), prototypical RXR agonist and HDAC inhibitor, respectively. Molecular docking studies demonstrate that this agent has a relatively strong affinity to RXR and HADC. Importantly, it presents the potentials of activation of RXR and inhibition of HDAC in both cell-free and whole-cell assays, and displays anti-proliferative effect on representative cancer cell lines and drug-resistant cancer cell lines.

[Research Progress on Distribution Characteristics and Formation Mechanisms of Microplastics in the Environment].

The extensive application of plastic products leads to the increasingly significant harm of plastic wastes to the ecological environment, which is also a focus of global environmental issues. Due to the lack of a sound plastic waste management system, most plastic waste is still treated by the traditional mode or remains in the environment, with low recycling efficiency, and the plastic life cycle has not yet formed. Plastics in the environment will age and degrade under the actions of physical (wear, waves), chemical (ultraviolet radiation, hydrolysis), and biological (fungi, bacteria) factors for a long time and generate micro (nano) plastics. Due to their small particle size, large specific surface area, and charged characteristics, in addition to their own toxicity, they can also be used as carriers or covert carriers of pollutants (heavy metals, persistent organic pollutants, polycyclic aromatic hydrocarbons, bacteria, etc.) to migrate in the environment through runoff, sewage discharge, and hydrometeorology, causing ecological environmental pollution. MPs pollution has been listed as the second largest scientific problem in the field of environmental and ecological science by the United Nations Environment Programme. MPs are widely distributed, and there are different degrees of MPs pollution in the global water (freshwater, ocean), soil, and atmospheric environment. Traces of MPs have also been found in human placentas, human breastmilk, living lungs, and blood in recent years. Therefore, the formation mechanisms of MPs under the actions of physics, chemistry, and microorganisms, as well as their abundance levels and migration characteristics in water, soil, and atmosphere environment were comprehensively reviewed, with the hope of providing reference for monitoring the pollution levels of MPs in the environment, exploring their transport laws in the environment, proposing the management strategy of MPs pollution, and revealing the degradation mechanisms of MPs under different effects.

Oligomer procyanidins (F2) repress HIF-1α expression in human U87 glioma cells by inhibiting the EGFR/ AKT/mTOR and MAPK/ERK1/2 signaling pathways in vitro and in vivo.

Hypoxia-inducible factor-1 (HIF-1) is over-expressed in gliomas and has become one of the most compelling tumor targets. In this study, we found that oligomer procyanidins (F2) can suppress the expressions of HIF-1α and its target genes in U87 cells, and also down-regulate the EGFR/PI3K/AKT/mTOR and MAPK/ERK1/2 pathways in vitro and in vivo. Furthermore, hypoxia-induced formation of tubular structures by human umbilical vascular endothelial cells and the migration and invasion of U87 cells could be inhibited by F2 in a HIF-1 dependent manner. Moreover, in a U87 xenograft tumor model, F2 significantly reduced intra-tumor vessel density and cell proliferation and finally retarded tumor growth, indicating that F2 may be a potential HIF-1 inhibitor and serve as one of candidates for glioma therapy.

Oligomer procyanidins (F2) isolated from grape seeds inhibits tumor angiogenesis and cell invasion by targeting HIF-1α in vitro.

Overexpression of hypoxia-inducible factor-1 (HIF-1) α, a transcription factor which immortalizes tumors by inducing expression of the genes involved in cell survival, migration and angiogenesis, is closely associated with poor prognosis, increased risk of metastasis and increased mortality. Oligomer procyanidins (F2), a natural fraction from grape seeds, has been demonstrated to have antioxidant and antitumor activities, however the antitumor effect of F2 targeting HIF-1α remains unknown. The present study showed that F2 markedly decreased HIF-1α and the expression of its target genes in cancer cells through inactivating the EGFR-PI3K-AKT-mTOR and MAPK-ERK1/2 pathways. Moreover, F2 suppressed vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP)-2 expressions, followed by the inhibition of tumor angiogenesis and cell invasion in a HIF-1α-dependent manner. Collectively, these findings indicate that the antitumor effect of F2 is, at least in part, mediated by suppressing HIF-1α-dependent pathway, and suggest that F2 may be a potentially useful agent for treatment of human cancer.