This study aims to explore the functions and mechanisms of long noncoding RNA small nucleolar RNA host gene 5 (SNHG5) in chronic constriction injury (CCI)-induced neuropathic pain (NP). An NP rat model was established using the CCI method and the NP severity was evaluated by paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). The expression of SNHG5, CDK9, and SCN9A was quantified in rat dorsal root ganglion, in addition to the detections of apoptosis, pathological changes, neuron number, and the co-localization of Nav1.7 and cleaved caspase-3 with NeuN. In ND7/23 cells, the apoptosis and lactate dehydrogenase concentration were assessed, as well as the relationship between SNHG5, CDK9, and SCN9A. In the dorsal root ganglion of CCI-treated rats, SNHG5 and SCN9A were upregulated and downregulation of SNHG5 suppressed SCN9A expression, increased the PWT and PWL, blocked neuroinflammation and neuronal apoptosis, and alleviated NP. Mechanistically, SNHG5 recruited CDK9 to enhance SCN9A-encoded Nav1.7 expression and promoted peripheral neuronal apoptosis and injury. In addition, SCN9A overexpression nullified the alleviative effects of SNHG5 deficiency on NP and neuron loss in CCI rats. In conclusion, SNHG5 promotes SCN9A-encoded Nav1.7 expression by recruiting CDK9, thereby facilitating neuron loss and NP after spinal nerve injury, which may offer a promising target for the management of NP.

Pain sensitization in spinal cord injury (SCI)-induced central neuropathic pain has been a research target. Additionally, suberoylanilide hydroxamic acid (SAHA) has been reported to protect against pain hypersensitivity in central neuropathic pain. Hence, this research probed the impact of SAHA on pain sensitization in central neuropathic pain after SCI via the HDAC5/NEDD4/SCN9A axis. After SAHA treatment, SCI modeling, and gain- and loss-of-function assays, behavioral analysis was performed in mice to evaluate pain hypersensitivity and anxiety/depression-like behaviors. The enrichment of H3K27Ac in the NEDD4 promoter and the ubiquitination of SCN9A were measured with ChIP and Co-IP assays, respectively. The treatment of SAHA regained paw withdrawal threshold and paw withdrawal latency values, entry time and numbers in the center area, and entry proportion in the open arm for SCI mice, accompanied by decreases in immobility time, eating latency, thermal hyperalgesia, and mechanical ectopic pain. However, SAHA treatment did not affect the motor function of mice. SAHA treatment lowered HDAC5 expression and SCN9A protein expression in SCI mice, as well as enhanced SCN9A ubiquitination and NEDD4 expression. HDAC5 knockdown greatly increased H3K27Ac enrichment in the NEDD4 promoter. NEDD4 upregulation or HDAC5 knockdown elevated SCN9A ubiquitination but diminished SCN9A protein expression in dorsal root ganglions of SCI mice. NEDD4 silencing mitigated the improving effects of SAHA treatment on the pain hypersensitivity and anxiety/depression-like behaviors of SCI mice. SAHA suppressed HDAC5 to augment NEDD4 expression and SCN9A degradation, thereby ameliorating the pain hypersensitivity and anxiety/depression-like behaviors of SCI mice.

Nav1.7 represents a preeminent target for next-generation analgesics for its critical role in pain sensation. Here we report a 2.2-Å resolution cryo-EM structure of wild-type (WT) Nav1.7 complexed with the β1 and β2 subunits that reveals several previously indiscernible cytosolic segments. Reprocessing of the cryo-EM data for our reported structures of Nav1.7(E406K) bound to various toxins identifies two distinct conformations of S6IV, one composed of α helical turns only and the other containing a π helical turn in the middle. The structure of ligand-free Nav1.7(E406K), determined at 3.5-Å resolution, is identical to the WT channel, confirming that binding of Huwentoxin IV or Protoxin II to VSDII allosterically induces the α → π transition of S6IV. The local secondary structural shift leads to contraction of the intracellular gate, closure of the fenestration on the interface of repeats I and IV, and rearrangement of the binding site for the fast inactivation motif.

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BACKGROUND: Intravenous lidocaine has been shown to reduce opioid consumption and is associated with favourable outcomes after surgery. In this study, we explored whether intraoperative lidocaine reduces intraoperative opioid use and length of stay (LOS) and improves long-term survival after primary debulking surgery for ovarian cancer and explored the correlation between SCN9A expression and ovarian cancer prognosis.
METHODS: This retrospective study included patients who underwent primary debulking surgery(PDS) for ovarian cancer from January 2015 to December 2018. The patients were divided into non-lidocaine and lidocaine [bolus injection of 1.5 mg/kg lidocaine at the induction of anaesthesia followed by a continuous infusion of 2 mg/(kg∙h) intraoperatively] groups. Intraoperative opioid consumption, the verbal numeric rating scale (VNRS) at rest and LOS were recorded. Propensity score matching was used to minimize bias, and disease-free survival (DFS) and overall survival (OS) were compared between the two groups.
RESULTS: After propensity score matching(PSM), the demographics were not significantly different between the groups. The intraoperative sufentanil consumption in the lidocaine group was significantly lower than that in the non-lidocaine group (Mean: 35.6 μg vs. 43.2 μg, P=0.035). LOS was similar between the groups (12.0 days vs. 12.4 days, P=0.386). There was a significant difference in DFS between the groups (32.3% vs. 21.6%, P=0.015), and OS rates were significantly higher in the lidocaine group than in the non-lidocaine group (35.2% vs. 25.6%, P=0.042). Multivariate analysis indicated that intraoperative lidocaine infusion was associated with prolonged OS and DFS.
CONCLUSIONS: Intraoperative intravenous lidocaine infusion appears to be associated with improved OS and DFS in patients undergoing primary debulking surgery for ovarian cancer. Our study has the limitations of a retrospective review. Hence, our results should be confirmed by a prospective randomized controlled trial.

Charcot neuroarthropathy is a systemic disease with pathological changes in the musculoskeletal system, which leads to fractures, dislocations, and deformities involving multiple bones and joints, particularly those of the feet. While the common underlying cause of Charcot neuroarthropathy is diabetes mellitus, it is also associated with congenital insensitivity to pain (CIP). CIP is a rare disorder caused by loss-of-function mutations in SCN9A encoding Nav1.7. In this study, we report a patient with CIP from a consanguineous family susceptible to Charcot neuroarthropathy with a novel SCN9A mutation. This report involves the case of a middle-aged man who suffered from CIP, had repeated painless fractures, and developed bone and joint destruction. The physical and radiological examinations revealed that multiple joints were swollen and deformed, and soft-tissue trauma was evident. We identified a novel homozygous SCN9A mutation (p.Cys1339Arg) by whole-exome sequencing (WES), which was verified using Sanger sequencing. In addition, the wild-type (WT) and mutated p. Cys1339Arg were assessed in HEK293 cells expressing Nav1.7, and the results showed that p. Cys1339Arg almost abolished the Nav1.7 sodium current. In conclusion, Charcot neuroarthropathy associated with CIP demonstrated a wider spectrum of Charcot neuroarthropathy than was previously recognized or documented. In addition, this finding is conducive to understanding the critical amino acids for maintaining the function of Nav1.7, thus contributing to the development of Nav1.7-targeted analgesics.

Congenital insensitivity to pain (OMIM 243000) is an extremely rare disorder caused by loss-of-function mutations in SCN9A encoding Nav1.7. Although the SCN9A mutations and phenotypes of painlessness and anosmia/hyposmia in patients are previously well documented, the complex relationship between genotype and phenotype of congenital insensitivity to pain remains unclear. Here, we report a congenital insensitivity to pain patient with novel SCN9A mutations. Functional significance of novel SCN9A mutations was assessed in HEK293 cells expressing Nav1.7, the results showed that p.Arg99His significantly decreased current density and reduced total Nav1.7 protein levels, whereas p.Trp917Gly almost abolished Nav1.7 sodium current without affecting its protein expression. These revealed that mutations in Nav1.7 in this congenital insensitivity to pain patient still retained partial channel function, but the patient showed completely painlessness, the unexpected genotypic-phenotypic relationship of SCN9A mutations in our patient may challenge the previous findings \"Nav1.7 total loss-of-function leads to painlessness.\" Additionally, these findings are helpful for understanding the critical amino acid for maintaining function of Nav1.7, thus contributing to the development of Nav1.7-targeted analgesics.

Generalized epilepsy with febrile seizures plus (GEFS+) is a complex familial epilepsy syndrome. It is mainly caused by mutations in SCN1A gene, encoding type 1 voltage-gated sodium channel α-subunit (NaV1.1), and GABRA1 gene, encoding the α1 subunit of the γ-aminobutyric acid type A (GABAA) receptor, while seldom related with SCN9A gene, encoding the voltage-gated sodium channel NaV1.7. In this study, we investigated a Chinese family with an autosomal dominant form of GEFS+. DNA sequencing of the whole coding region revealed a novel heterozygous nucleotide substitution (c.5873A>G) causing a missense mutation (p.Y1958C). This mutation was predicted to be deleterious by three different bioinformatics programs (The polyphen2, SIFT, and MutationTaster). Our finding reports a novel likely pathogenic SCN9A Y1958C heterozygous mutation in a Chinese family with GEFS+ and provides additional supports that SCN9A variants may be associated with human epilepsies.

OBJECTIVE: This study aimed to identify disease-causing gene mutations in individuals belonging to the Southern Chinese Han population diagnosed with fever-associated seizures or epilepsy (FASE).
METHODS: Blood samples and clinical data were collected from 78 children with FASE. All subjects were screened for mutations using whole-exome sequencing, and mutations were validated using the Sanger sequencing method.
RESULTS: Three novelSCN9A heterozygous missense mutations (I775M, R429C and A442T) were noted, which are associated with febrile seizures (FS), febrile seizures plus (FS+) and genetic epilepsy with febrile seizures plus (GEFS+), respectively. The R429C and A442T mutations are located in the large cytoplasmic loop between transmembrane topological domains, whereas I775M is located in the topological domain DIIS2. The I775M and R429C mutations have highly evolutionarily conserved residues and are predicted to affect the SCN9A protein function according to bioinformatics tools. These three mutations were not identified in 300 unrelated control subjects.
CONCLUSIONS: Mutations in theSCN9A gene may be linked with FASE.

Genetic mutants of voltage-gated sodium channels (VGSCs) are considered to be responsible for the increasing number of epilepsy syndromes. Previous research has indicated that mutations of one of the VGSC genes, SCN9A (Nav1.7), result in febrile seizures and Dravet syndrome in humans. Despite these recent efforts, the electrophysiological basis of SCN9A mutations remains unclear. Here, we performed a genetic screen of patients with febrile seizures and identified a novel missense mutation of SCN9A (W1150R). Electrophysiological characterization of different SCN9A mutants in HEK293T cells, the previously-reported N641Y and K655R variants, as well as the newly-found W1150R variant, revealed that the current density of the W1150R and N641Y variants was significantly larger than that of the wild-type (WT) channel. The time constants of recovery from fast inactivation of the N641Y and K655R variants were markedly lower than in the WT channel. The W1150R variant caused a negative shift of the G-V curve in the voltage dependence of steady-state activation. All mutants displayed persistent currents larger than the WT channel. In addition, we found that oxcarbazepine (OXC), one of the antiepileptic drugs targeting VGSCs, caused a significant shift to more negative potential for the activation and inactivation in WT and mutant channels. OXC-induced inhibition of currents was weaker in the W1150R variant than in the WT. Furthermore, with administering OXC the time constant of the N641Y variant was longer than those of the other two SCN9A mutants. In all, our results indicated that the point mutation W1150R resulted in a novel gain-of-function variant. These findings indicated that SCN9A mutants contribute to an increase in seizure, and show distinct sensitivity to OXC.