Integrins are a family of transmembrane glycoproteins that mediate cell-cell and cell-extracellular matrix interactions. The integrin α4 subunit is widely expressed by cells from the immune system and its expression ...Integrins are a family of transmembrane glycoproteins that mediate cell-cell and cell-extracellular matrix interactions. The integrin α4 subunit is widely expressed by cells from the immune system and its expression by non-hematopoietic cells is scarce. In the present study, gene and protein expression of this integrin subunit was characterized in proliferating and quiescent human RPE cells. Immunofluorescent studies confirm that the α4 subunit is expressed in vitro by RPE cells, a result that has been validated by immunofluorescence and FACS analyses. The accumulation of the α4 integrin at cell-cell junctions in post-confluent RPE cell cultures negatively correlated with the level of expression of the mRNA transcript. Accordingly, transient transfection analyses reveal that the α4 promoter activity is considerably reduced when RPE cells form a confluent monolayer. Moreover, transfection of recombinant constructs bearing 5’-deletions of the α4 promoter segment allows the localization of strong negative regulatory elements on the -76 to -300 region of the α4 gene suggesting that its expression is intimately linked to the proliferative state of primary cultured RPE cells.展开更多
Background:Because of its superficial anatomical localization,the cornea is particularly vulnerable to abrasive forces and various traumas,which can lead to significant visual impairments.Upon injury of the corneal ep...Background:Because of its superficial anatomical localization,the cornea is particularly vulnerable to abrasive forces and various traumas,which can lead to significant visual impairments.Upon injury of the corneal epithelium,there are important changes that occur in the composition of the underlying extracellular matrix(ECM).Those changes are perceived by the integrins that recognize the ECM components as their ligand and activate different intracellular signalling pathways,ultimately leading to reepithelialisation and reorganization of the injured epithelium,both of which are necessary in order to restore the visual properties of the cornea.The goal of this study was to analyse the impact of the pharmacological inhibition of specific signal transduction mediators of integrin-dependant signalling pathways on corneal wound healing using both monolayers of hCECs and tissue-engineered human corneas(hTECs)as in vitro models.Methods:hTECs were produced by the self-assembly approach and wounded with a 8-mm diameter biopsy punch.Total RNA and proteins were isolated from the wounded and unwounded hTECs to conduct gene profiling analyses and protein kinase arrays.The wounded tissues were then incubated with the WNK1 inhibitor WNK463 and wound healing was monitored over a period of 6 days.Control corneas were incubated with the vehicle alone(DMSO).The impact of WNK1 inhibition on hCECs monolayers was determined using a scratch wound assay.Results:Gene profiling analyses and protein kinases arrays revealed important alterations in the expression and activity of several mediators from the integrin-dependent signalling pathways in response to the ECM changes taking place during corneal wound healing.Among these,WNK1 is considerably activated through phosphorylation during corneal wound healing.The pharmacological inhibition of WNK1 by WNK463 significantly reduced the dynamic of corneal wound closure in our hTECs and hCECs monolayers compared to their respective negative controls.Conclusions:These results allowed the identification of WNK1 kinase as an important player for a proper healing of the cornea.Also,these results allowed for a better understanding of the cellular and molecular mechanisms involved in corneal wound healing and they may lead to the identification of new therapeutic targets in the field of corneal wounds.展开更多
Background:The cornea composes the outer surface of the eye and its transparency is required to allow light transmission to the retina.However,because of its position,the cornea is subjected to chemical and mechanical...Background:The cornea composes the outer surface of the eye and its transparency is required to allow light transmission to the retina.However,because of its position,the cornea is subjected to chemical and mechanical injuries that may lead to blindness.Our studies conducted using the human tissue-engineered cornea(hTEC)as a model provided evidence that the cyclic-AMP-response element binding protein(CREB)pathway is repressed during closure of corneal wounds.Based on these results,we hypothesized that closure of corneal wounds can be enhanced by preventing activation of CREB with the pharmacological inhibitor C646.Our goals were to proceed to the pharmacological inhibition of CREB(I)in vitro using the hTECs as a model,and then(II)in vivo using the rabbit as a model.Methods:The self-assembly approach was used to create hTECs,that were then wounded with an 8-mm diameter biopsy punch to create an epithelial defect.The tissues were then incubated with 10μM of C646(n=8).DMSO was used alone as a negative control(n=4).Closure of the wounds was monitored over a period of 5 days.Besides,the cornea of New Zealand white rabbits was debrided with an ethanol 70%solution to create an epithelial defect of 8-mm diameter.Several concentrations of C646(1,10,100μM et 1 mM)were applied as eye drops 3 times a day for up to 7 days.The wounded corneas(n=4 per concentration)were stained with fluorescein and photographed every day.Results:In vitro pharmacological inhibition of CREB with C646 considerably accelerated wound closure of all treated hTECs(4 days)compared to the control group(7 days).Moreover,the in vivo C646 treatment also accelerated wound healing of the corneas compared to the control group.The most effective concentration of C646 tested was the lowest(1μM),as it considerably enhanced the wound healing process.Conclusions:This study demonstrates that wound healing both in vitro and in vivo can be enhanced by preventing activation of CREB using a pharmacological inhibition approach.Most of all,this experiment suggests mediators from the CREB pathway as potential therapeutic targets on which we may influence to alter the wound healing dynamic of the cornea.We believe this study will lead to significant advancements in the clinical field of corneal defects.展开更多
文摘Integrins are a family of transmembrane glycoproteins that mediate cell-cell and cell-extracellular matrix interactions. The integrin α4 subunit is widely expressed by cells from the immune system and its expression by non-hematopoietic cells is scarce. In the present study, gene and protein expression of this integrin subunit was characterized in proliferating and quiescent human RPE cells. Immunofluorescent studies confirm that the α4 subunit is expressed in vitro by RPE cells, a result that has been validated by immunofluorescence and FACS analyses. The accumulation of the α4 integrin at cell-cell junctions in post-confluent RPE cell cultures negatively correlated with the level of expression of the mRNA transcript. Accordingly, transient transfection analyses reveal that the α4 promoter activity is considerably reduced when RPE cells form a confluent monolayer. Moreover, transfection of recombinant constructs bearing 5’-deletions of the α4 promoter segment allows the localization of strong negative regulatory elements on the -76 to -300 region of the α4 gene suggesting that its expression is intimately linked to the proliferative state of primary cultured RPE cells.
文摘Background:Because of its superficial anatomical localization,the cornea is particularly vulnerable to abrasive forces and various traumas,which can lead to significant visual impairments.Upon injury of the corneal epithelium,there are important changes that occur in the composition of the underlying extracellular matrix(ECM).Those changes are perceived by the integrins that recognize the ECM components as their ligand and activate different intracellular signalling pathways,ultimately leading to reepithelialisation and reorganization of the injured epithelium,both of which are necessary in order to restore the visual properties of the cornea.The goal of this study was to analyse the impact of the pharmacological inhibition of specific signal transduction mediators of integrin-dependant signalling pathways on corneal wound healing using both monolayers of hCECs and tissue-engineered human corneas(hTECs)as in vitro models.Methods:hTECs were produced by the self-assembly approach and wounded with a 8-mm diameter biopsy punch.Total RNA and proteins were isolated from the wounded and unwounded hTECs to conduct gene profiling analyses and protein kinase arrays.The wounded tissues were then incubated with the WNK1 inhibitor WNK463 and wound healing was monitored over a period of 6 days.Control corneas were incubated with the vehicle alone(DMSO).The impact of WNK1 inhibition on hCECs monolayers was determined using a scratch wound assay.Results:Gene profiling analyses and protein kinases arrays revealed important alterations in the expression and activity of several mediators from the integrin-dependent signalling pathways in response to the ECM changes taking place during corneal wound healing.Among these,WNK1 is considerably activated through phosphorylation during corneal wound healing.The pharmacological inhibition of WNK1 by WNK463 significantly reduced the dynamic of corneal wound closure in our hTECs and hCECs monolayers compared to their respective negative controls.Conclusions:These results allowed the identification of WNK1 kinase as an important player for a proper healing of the cornea.Also,these results allowed for a better understanding of the cellular and molecular mechanisms involved in corneal wound healing and they may lead to the identification of new therapeutic targets in the field of corneal wounds.
文摘Background:The cornea composes the outer surface of the eye and its transparency is required to allow light transmission to the retina.However,because of its position,the cornea is subjected to chemical and mechanical injuries that may lead to blindness.Our studies conducted using the human tissue-engineered cornea(hTEC)as a model provided evidence that the cyclic-AMP-response element binding protein(CREB)pathway is repressed during closure of corneal wounds.Based on these results,we hypothesized that closure of corneal wounds can be enhanced by preventing activation of CREB with the pharmacological inhibitor C646.Our goals were to proceed to the pharmacological inhibition of CREB(I)in vitro using the hTECs as a model,and then(II)in vivo using the rabbit as a model.Methods:The self-assembly approach was used to create hTECs,that were then wounded with an 8-mm diameter biopsy punch to create an epithelial defect.The tissues were then incubated with 10μM of C646(n=8).DMSO was used alone as a negative control(n=4).Closure of the wounds was monitored over a period of 5 days.Besides,the cornea of New Zealand white rabbits was debrided with an ethanol 70%solution to create an epithelial defect of 8-mm diameter.Several concentrations of C646(1,10,100μM et 1 mM)were applied as eye drops 3 times a day for up to 7 days.The wounded corneas(n=4 per concentration)were stained with fluorescein and photographed every day.Results:In vitro pharmacological inhibition of CREB with C646 considerably accelerated wound closure of all treated hTECs(4 days)compared to the control group(7 days).Moreover,the in vivo C646 treatment also accelerated wound healing of the corneas compared to the control group.The most effective concentration of C646 tested was the lowest(1μM),as it considerably enhanced the wound healing process.Conclusions:This study demonstrates that wound healing both in vitro and in vivo can be enhanced by preventing activation of CREB using a pharmacological inhibition approach.Most of all,this experiment suggests mediators from the CREB pathway as potential therapeutic targets on which we may influence to alter the wound healing dynamic of the cornea.We believe this study will lead to significant advancements in the clinical field of corneal defects.
