Long noncoding RNA H19 regulates degeneration and regeneration of injured peripheral nerves

Our previous studies have shown that long noncoding RNA(lncRNA)H19 is upregulated in injured rat sciatic nerve during the process of Wallerian degeneration,and that it promotes the migration of Schwann cells and slows down the growth of dorsal root ganglion axons.However,the mechanism by which lncRNA H19 regulates neural repair and regeneration after peripheral nerve injury remains unclear.In this study,we established a Sprague-Dawley rat model of sciatic nerve transection injury.We performed in situ hybridization and found that at 4–7 days after sciatic nerve injury,lncRNA H19 was highly expressed.At 14 days before injury,adeno-associated virus was intrathecally injected into the L4–L5 foramina to disrupt or overexpress lncRNA H19.After overexpression of lncRNA H19,the growth of newly formed axons from the sciatic nerve was inhibited,whereas myelination was enhanced.Then,we performed gait analysis and thermal pain analysis to evaluate rat behavior.We found that lncRNA H19 overexpression delayed the recovery of rat behavior function,whereas interfering with lncRNA H19 expression improved functional recovery.Finally,we examined the expression of lncRNA H19 downstream target SEMA6D,and found that after lncRNA H19 overexpression,the SEMA6D protein level was increased.These findings suggest that lncRNA H19 regulates peripheral nerve degeneration and regeneration through activating SEMA6D in injured nerves.This provides a new clue to understand the role of lncRNA H19 in peripheral nerve degeneration and regeneration.

Expression and alteration of insulin-like growth factor II-messenger RNA in hepatoma tissues and peripheral blood of patients with hepatocellular carcinoma

AIM: To investigate the clinical values of serum free insulin-like growth factor Ⅱ (IGF-Ⅱ) levels and IGF-Ⅱ mRNA in hepatocellular carcinoma (HCC) tissues and peripheral blood for diagnosis of HCC and monitoring of extrahepatic metastasis.METHODS: Total RNAs were extracted from HCC tissues or peripheral blood mononuclear cells from patients with HCC, liver diseases devoid of cancer, non-hepatic tumors,and healthy controls, respectively. IGF-Ⅱ cDNAs were synthesized through random primers and reversetranscriptase, amplified by polymerase chain reaction (PCR), and confirmed by DNA sequencing analysis. Serum free IGF-Ⅱ levels in patients with different liver diseases were analyzed by an enzyme-linked immunosorbent assay.RESULTS: The amplified fragments of IGF-Ⅱ mRNA by RT-PCR were identical to originally designed ones with a size of 170 bp and confirmed by sequencing analysis.The dilution experiments revealed that the lowest sensitivity of our system was 2 ng/L of total RNA. The positive frequencies of IGF-Ⅱ mRNA were 100% in HCC tissues,53.3% in para-cancerous tissues, and 0% in non-cancerous tissues, respectively. The serum free IGF-Ⅱ levels were significantly higher in HCC than those in chronic hepatitis or liver cirrhosis. The positive frequency of circulating IGF-Ⅱ mRNA was 34.2% in HCC, no amplified fragment was found in other liver diseases, extrahepatic tumors,and normal controls, respectively. The circulating IGF-Ⅱ mRNA correlated with the stage of HCC, and its positive rate was 100% in HCC with extrahepatic metastasis and 35.5% in HCC with AFP-negative. No significant correlation was found between tumor sizes and circulating IGF-Ⅱ mRNA fragment.CONCLUSION: The abnormal expressions of free IGF-Ⅱ and IGF-Ⅱ mRNA are useful tumor markers for HCC diagnosis, differentiation of extrahepatic metastasis and monitoring postoperative recurrence.

Dynamic alteration of telomerase expression and its diagnostic significance in liver or peripheral blood for hepatocellular carcinoma

AIM： To investigate the dynamic alteration of telomerase expression during development of hepatocellular carcinoma （HCC） and its diagnostic implications in liver tissues or peripheral blood mononuclear cells for HCC. METHODS： Dynamic expressions of liver telomerase during malignant transformation of hepatocytes were observed in Sprague-Dawly （SD） rats fed with 0.05% of 2-fluoenyacetamide （2-FAA）. Total RNA and telomerase were extracted from rat or human liver tissues. The telomerase activities in livers and in circulating blood were detected by a telomeric repeat amplification protocol-enzyme-linked immunosorbent assay （TRAP- ELISA）, and its diagnostic value was investigated in patients with benign or malignant liver diseases. RESULTS： The hepatoma model displayed the dynamic expression of hepatic telomerase during HCC development. The telomerase activities were consistent with liver total RNA levels （r = 0.83, P 〈 0.01） at the stages of degeneration, precancerosis, and cancerization of hepatocytes. In HCC patients, the telomerase levels in HCC tissues were significantly higher than in their adjacent non-cancerous tissues, but liver total RNA levels were lower in the former than in the latter. Although the circulating telomerase of HCC patients was abnormally expressed among patients with chronic liver diseases, the telomerase activity was a non-specific marker for HCC diagnosis, because the incidence was 15.7% in normal control, 25% in chronic hepatitis, 45.9% in liver cirrhosis, and 85.2% in HCC, respectively when absorbance value of telomerase activity was more than 0.2. If the value was over 0.6, the incidence was 60% in HCC group and 0% in any of the others （P 〈 0.01） except in two cases with liver cirrhosis. However, the combination of circulating telomerase with serum alpha-fetoprotein level could increase the positive rate and the accuracy （92.6%, 125 of 135） of HCC diagnosis. CONCLUSION： The overexpression of telomerase is associated with HCC development, and its abnormality in liver tissues or in peripheral blood could be a useful marker for diagnosis and prognosis of HCC.

Mitochondrial carnitine palmitoyl transferase-Ⅱ inactivity aggravates lipid accumulation in rat hepatocarcinogenesis

AIM To investigate the dynamic alteration of mitochondrial carnitine palmitoyl transferase Ⅱ(CPT-Ⅱ) expression during malignant transformation of rat hepatocytes.METHODS Sprague-Dawley male rats were fed with normal, high fat(HF), and HF containing 2-fluorenylacetamide(2-FAA) diet, respectively. According to the Hematoxylin and Eosin staining of livers, rats were divided into control, fatty liver, degeneration, pre-cancerous, and cancerous groups. Liver lipids were dyed with Oil Red O, CPT-Ⅱ alterations were analyzed by immunohistochemistry, and compared with CPT-Ⅱ specific concentration(μg/mg protein). Levels of total cholesterol(Tch), triglyceride(TG), and aminotransferases [alanine aminotransferase(ALT), aspartate aminotransferase(AST)] were determined by the routine methods.RESULTS After intake of HF and/or HF+2-FAA diets, the rat livers showed mass lipid accumulation. The lipid level in the control group was significantly lower than that in other groups. The changes of serum TG and Tch levels were abnormally increasing, 2-3 times more than those in the controls(P < 0.05). During the rat liver morphological changes from normal to cancer development process with hepatocyte injury, serum AST and ALT levels were significantly higher(4-8 times, P < 0.05) than those in the control group. The specific concentration of CPT-Ⅱ in liver tissues progressively decreased during hepatocyte malignant transformation, with the lowest CPT-Ⅱ levels in the cancer group than in any of the other groups(P < 0.05).CONCLUSION Low CPT-Ⅱ expression might lead to abnormal hepatic lipid accumulation, which should promote the malignant transformation of hepatocytes.

Claudin-15 overexpression inhibits proliferation and promotes apoptosis of Schwann cells in vitro

Our previous experiments have discovered that Claudin-15 was up-regulated in Schwann cells of the distal nerve stumps of rat models of sciatic nerve injury.However,how Claudin-15 affects Schwann cell function is still unknown.This study aimed to identify the effects of Claudin-15 on proliferation and apoptosis of Schwann cells cultured in vitro and explore the underlying mechanisms.Primary Schwann cells were obtained from rats.Claudin-15 in Schwann cells was knocked down using siRNA(siRNA-1 group)compared with the negative control siRNA transfection group(negative control group).Claudin-15 in Schwann cells was overexpressed using pGV230-Claudin-15 plasmid(pGV230-Claudin-15 group).The pGV230 transfection group(pGV230 group)acted as the control of the pGV230-Claudin-15 group.Cell proliferation was analyzed with EdU assay.Cell apoptosis was analyzed with flow cytometric analysis.Cell migration was analyzed with Transwell inserts.The mRNA and protein expressions were analyzed with quantitative polymerase chain reaction assay and western blot assay.The results showed that compared with the negative control group,cell proliferation rate was up-regulated;p-AKT/AKT ratio,apoptotic rate,p-c-Jun/c-Jun ratio,mRNA expression of protein kinase C alpha,Bcl-2 and Bax were down-regulated;and mRNA expression of neurotrophins basic fibroblast growth factor and neurotrophin-3 were increased in the siRNA-1 group.No significant difference was found in cell migration between the negative control and siRNA-1 groups.Compared with the pGV230 group,the cell proliferation rate was down-regulated;apoptotic rate,p-c-Jun/c-Jun ratio and c-Fos protein expression increased;mRNA expression of protein kinase C alpha and Bax decreased;and mRNA expressions of neurotrophins basic fibroblast growth factor and neurotrophin-3 were up-regulated in the pGV230-Claudin-15 group.The above results demonstrated that overexpression of Claudin-15 inhibited Schwann cell proliferation and promoted Schwann cell apoptosis in vitro.Silencing of Claudin-15 had the reverse effect and provided neuroprotective effect.This study was approved by the Experimental Animal Ethics Committee of Jilin University of China(approval No.2016-nsfc001)on March 5,2016.

Baculoviral inhibitor of apoptosis protein repeatcontaining protein 3 delays early Wallerian degeneration after sciatic nerve injury

Wallerian degeneration is a complex biological process that occurs after nerve injury,and involves nerve degeneration and regeneration.Schwann cells play a crucial role in the cellular and molecular events of Wallerian degeneration of the peripheral nervous system.However,Wallerian degeneration regulating nerve injury and repair remains largely unknown,especially the early response.We have previously reported some key regulators of Wallerian degeneration after sciatic nerve injury.Baculoviral inhibitor of apoptosis protein repeat-containing protein 3(BIRC3)is an important factor that regulates apoptosis-inhibiting protein.In this study,we established rat models of right sciatic nerve injury.In vitro Schwann cell models were also established and subjected to gene transfection to inhibit and overexpress BIRC3.The data indicated that BIRC3 expression was significantly up-regulated after sciatic nerve injury.Both BIRC3 upregulation and downregulation affected the migration,proliferation and apoptosis of Schwan cells and affected the expression of related factors through activating c-fos and ERK signal pathway.Inhibition of BIRC3 delayed early Wallerian degeneration through inhibiting the apoptosis of Schwann cells after sciatic nerve injury.These findings suggest that BIRC3 plays an important role in peripheral nerve injury repair and regeneration.The study was approved by the Institutional Animal Care and Use Committee of Nantong University,China(approval No.2019-nsfc004)on March 1,2019.

Claudin 14/15 play important roles in early wallerian degeneration after rat sciatic nerve injury

Purpose:Wallerian degeneration(WD)is an antegrade degenerative process distal to peripheral nerve injury.Numerous genes are differentially regulated in response to the process.However,the underlying mechanism is unclear,especially the early response.We aimed at investigating the effects of sciatic nerve injury on WD via CLDN 14/15 interactionsin vivo andin vitro.Methods:Using the methods of molecular biology and bioinformatics analysis,we investigated the molecular mechanism by which claudin 14/15 participate in WD.Our previous study showed that claudins 14 and 15 trigger the early signal flow and pathway in damaged sciatic nerves.Here,we report the effects of the interaction between claudin 14 and claudin 15 on nerve degeneration and regeneration during early WD.Results:It was found that claudin 14/15 were upregulated in the sciatic nerve in WD.Claudin 14/15 promoted Schwann cell proliferation,migration and anti-apoptosisin vitro.PKCα,NT3,NF2,and bFGF were significantly upregulated in transfected Schwann cells.Moreover,the expression levels of theβ-catenin,p-AKT/AKT,p-c-jun/c-jun,and p-ERK/ERK signaling pathways were also significantly altered.Conclusion:Claudin 14/15 affect Schwann cell proliferation,migration,and anti-apoptosis via theβ-catenin,p-AKT/AKT,p-c-jun/c-jun,and p-ERK/ERK pathwaysin vitro andin vivo.The results of this study may help elucidate the molecular mechanisms of the tight junction signaling pathway underlying peripheral nerve degeneration.