Pterygium epithelium abnormal differentiation related to activation of extracellular signal-regulated kinase signaling pathway in vitro

AIMTo investigate whether the abnormal differentiation of the pterygium epithelium is related to the extracellular signal-regulated kinase (ERK) signaling pathway in vitro.METHODSThe expression levels of phosphorylated ERK (P-ERK), keratin family members including K19 and K10 and the ocular master control gene Pax-6 were measured in 16 surgically excised pterygium tissues and 12 eye bank conjunctiva. In colony-forming cell assays, the differences in clone morphology and in K10, K19, P-ERK and Pax-6 expression between the head and body were investigated. When cocultured with the ERK signaling pathway inhibitor PD98059, the changes in clone morphology, colony-forming efficiency, differentiated marker K10, K19 and Pax-6 expression and P-ERK protein expression level were examined by immunoreactivity and Western blot analysis.RESULTSThe expression of K19 and Pax-6 decreased in the pterygium, especially in the head. No staining of K10 was found in the normal conjunctiva epithelium, but it was found to be expressed in the superficial cells in the head of the pterygium. Characteristic upregulation of P-ERK was observed by immunohistochemistry. The clone from the head with more differentiated cells in the center expressed more K10, and the clone from the body expressed more K19. The P-ERK protein level increased in the pterygium epithelium compared with conjunctiva and decreased when cocultured with PD98059. The same medium with the ERK inhibitor PD98059 was more effective in promoting clonal growth than conventional medium with 3T3 murine feeder layers. It was observed that the epithelium clone co-cultured with the inhibitor had decreased K10 expression and increased K19 and Pax-6 expression.CONCLUSIONWe suggest ERK signaling pathway activation might play a role in the pterygium epithelium abnormal differentiation.

Isoleucine, an Essential Amino Acid, Induces the Expression of Human <i>β</i>Defensin 2 through the Activation of the G-Protein Coupled Receptor-ERK Pathway in the Intestinal Epithelia

Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.

Identification of key genes involved in axon regeneration and Wallerian degeneration by weighted gene co-expression network analysis

Peripheral nerve injury repair requires a certain degree of cooperation between axon regeneration and Wallerian degeneration.Therefore,investigating how axon regeneration and degeneration work together to repair peripheral nerve injury may uncover the molecular mechanisms and signal cascades underlying peripheral nerve repair and provide potential strategies for improving the low axon regeneration capacity of the central nervous system.In this study,we applied weighted gene co-expression network analysis to identify differentially expressed genes in proximal and distal sciatic nerve segments from rats with sciatic nerve injury.We identified 31 and 15 co-expression modules from the proximal and distal sciatic nerve segments,respectively.Functional enrichment analysis revealed that the differentially expressed genes in proximal modules promoted regeneration,while the differentially expressed genes in distal modules promoted neurodegeneration.Next,we constructed hub gene networks for selected modules and identified a key hub gene,Kif22,which was up-regulated in both nerve segments.In vitro experiments confirmed that Kif22 knockdown inhibited proliferation and migration of Schwann cells by modulating the activity of the extracellular signal-regulated kinase signaling pathway.Collectively,our findings provide a comparative framework of gene modules that are co-expressed in injured proximal and distal sciatic nerve segments,and identify Kif22 as a potential therapeutic target for promoting peripheral nerve injury repair via Schwann cell proliferation and migration.All animal experiments were approved by the Institutional Animal Ethics Committee of Nantong University,China(approval No.S20210322-008)on March 22,2021.

Combination of Quercetin, Hirudin and Cinnamaldehyde Promotes Schwann Cell Differentiation and Myelination against High Glucose by Inhibiting ERK Signaling Pathway

Objective:To investigate the therapeutic and synergistic effects of QHC(combination of quercetin(Q),hirudin(H)and cinnamaldehyd(C))on Schwann cell differentiation and myelination against high glucose(HG)induced injury.Methods:Primary-culture Schwann cells exposed to HG(50 mmol/L)for 72 h and Schwann cell–dorsal root ganglion(DRG)neuron cocultures exposed to HG(50 mmol/L)for 7 days were employed as in vitro model of diabetic neuropathy.The cells were randomly divided into 10 groups:control(CON,25 mmol/L glucose),HG(50 mmol/L glucose),HG plus 10μmol/L quercetin(Q),HG plus 0.04 IU/mL hirudin(H),HG plus 100 nmol/L cinnamaldehyd(C),HG plus 10μmol/L quercetin and 0.04 IU/mL hirudin(QH),HG plus 10μmol/L quercetin and 50 nmol/L cinnamaldehyd(QC),HG plus 0.04 IU/mL hirudin and 50 nmol/L cinnamaldehyd(HC),HG plus 10μmol/L quercetin,0.04 IU/mL hirudin and 50 nmol/L cinnamaldehyd(QHC)or 10μmol/L U0126.Cell differentiation was evaluated by periaxin immunofluorescence staining.The protein expression levels of myelin protein zero(P0),myelin basic protein(MBP),myelin-associated glycoprotein(MAG),extracellular signal-regulated kinase(ERK),p-ERK,p-c-Jun,c-Jun,notch intracellular domain(NICD)and the mRNA expression levels of P0,MBP,MAG,Krox-20,Notch1 and Jagged1 were detected by Western blotting and real-time quantitative PCR analysis.The secretion of ciliary neurotrophic factor(CNTF)was determined by enzyme-linked immunosorbent assay(ELISA).The number and length of the myelin segments were evaluated by MBP immunofluorescence staining.The expression and the location of p-ERK in cocultures were detected by MAG and p-ERK immunofluorescence double staining.Results:Co-treatment with Q,C,H and their combination promoted Schwann cell differentiation,increased CNTF secretion,up-regulated the protein and m RNA expressions of myelin,and increased the number and length of the myelin segments(P<0.01 or P<0.05).In particular,the combination therapy of Q,H and C was superior to the respective monotherapy(P<0.01).Combination therapy of QHC exhibited higher inhibitory activities for ERK signaling related molecules than each monomer or the combination of the two monomers(P<0.01).Conclusions:QHC combination yielded synergy in promoting Schwann cell differentiation and myelination and the protective effect may involve in the inhibition of ERK signaling pathway,providing scientific evidence for better understanding of combination of Q,H and C in clinical applications.