Role of Moesin Phosphorylation in Retinal Pericyte Migration and Detachment Induced by Advanced Glycation Endproducts.

Proliferative diabetic retinopathy (PDR) involves persistent, uncontrolled formation of premature blood vessels with reduced number of pericytes. Our previous work showed that advanced glycation endproducts (AGEs) induced angiogenesis in human umbilical vein endothelial cells, mouse retina, and aortic ring, which was associated with moesin phosphorylation. Here we investigated whether moesin phosphorylation may contribute to pericyte detachment and the development of PDR. Primary retinal microvascular pericytes (RMPs) were isolated, purified from weanling rats, and identified by cellular markers α-SMA, PDGFR-ß, NG2, and desmin using immunofluorescence microscopy. Effects of AGE-BSA on proliferation and migration of RMPs were examined using CCK-8, wound healing, and transwell assays. Effects on moesin phosphorylation were examined using western blotting. The RMP response to AGE-BSA was also examined when cells expressed the non-phosphorylatable Thr558Ala mutant or phospho-mimicking Thr558Asp mutant of moesin or were treated with ROCK inhibitor Y27632. Colocalization and interaction between CD44, phospho-moesin, and F-actin were observed. Experiments with cultured primary RMPs showed that AGE-BSA inhibited the proliferation, enhanced the migration, and increased moesin phosphorylation in a dose- and time-dependent manner. AGE-BSA also triggered the rearrangement of F-actin and promoted the interaction of CD44 with phospho-moesin in RMPs. These effects were abrogated in cells expressing the non-phosphorylatable moesin mutant and the application of ROCK inhibitor Y27632 attenuated AGE-induced alteration in cultured RMPs by abolishing the phosphorylation of moesin. However, those AGE-induced pathological process occurred in RMPs expressed the phospho-mimicking moesin without AGE-BSA treatment. It is concluded that AGEs could activate ROCK to mediate moesin phosphorylation at Thr558, and resulting phospho-moesin interacts with CD44 to form CD44 cluster, which might stimulate the migration of RMPs and subsequent RMP detachment in microvessel. This pathway may provide new drug targets against immature neovessel formation in PDR.

Proteomic research of human retinal microvascular pericytes stimulated with high glucose / 中华实验眼科杂志

Objective@#To determine the changes of protein expressions in human retinal microvascular pericytes (HRMPCs) stimulated with high glucose by using quantitative proteomics, which provides new clues for future investigation of diabetic retinopathy (DR).@*Methods@#HRMPCs were divided into two groups.The cells in control group were cultured in DMEM basic medium with 25 mmol/L glucose, while the cells in high glucose group were cultured in DMEM medium with 35 mmol/L glucose.The amount of living cells was measured by cell counting kit-8(CCK-8). The proteins were collected from the two groups and then were digested with trypsin.Peptides of 2 μg were injected into the time of flight-mass spectrometer and the acquisition mode was DDA.The results were further analyzed using bioinformatics software.@*Results@#CCK-8 results showed that the absorbance (A450) of HRMPCs in high glucose group was 0.75±0.04, which was significantly lower than 0.91±0.05 in control group (t=5.784, P=0.000 2). In total, 1 972 proteins were identified and 54 of them were significantly different between the two groups (fold change >1.5). Among them, 13 proteins were up-regulated, including CTNNB1 and CTBP2; while 41 proteins were down-regulated, including SQSTM1 and HMGCS1.The differentially expressed proteins were mainly involved in citric acid cycle and aerobic respiration.@*Conclusions@#The expressions of many proteins in HRMPCs change under the stimulation of high glucose, which may influence the respiration and the ATP production of cells and eventually induce the loss of pericyte.

Purification and cultivation of mouse primary retinal microvascular pericytes based on pre-incubation / 中华实验眼科杂志

Objective@#To establish a simple method for isolation, purification and cultivation of primary retinal microvascular pericytes (RMPs) from mice.@*Methods@#Retinas were isolated from mice following with mechanical morcel, enzymatic digestion and filtration.The retinal fragments were incubated with low glucose DMEM with 20% fetal bovine serum after 24 hours pre-incubation.Differential digestion was used for purification of primary RMPs.Morphological examination of cells was performed by phase contrast microscopy, and further characterization was analyzed by immunocytochemistry.Functional assay was evaluated by the pericytes-endothelial cells (ECs) co-culture system.The treatment and use of experimental animals followed the regulations on the administration of experimental animals promulgated by the state science and technology commission.@*Results@#Cells migrated out of fragments after 24 hours of incubation, and developed into small or large colonies gradually.The cells and their subpassages presented typical pericyte morphology with large irregular triangular cell bodies and multiple long processes.No contact inhibition was observed.Most cells uniformly expressed the cellular markers α-smooth muscle actin (α-SMA) and platelet-derived growth factor receptor-β (PDGFR-β), a few cells expressed the cellular markers glial fibrillary acidic protein (GFAP), but no cell expressed von Willebrand factor (vWF). The purity rate of RMPs was up to 97%.In the co-culture system, RMPs directly contacted with ECs to form the capillary-like cords in vitro.@*Conclusions@#A simple method for the isolation, purification cultivation of mouse RMPs is established, and active RMPs can be readily obtained by this method.

Purification and cultivation of mouse primary retinal microvascular pericytes based on pre-incubation / 中华实验眼科杂志

Objective To establish a simple method for isolation, purification and cultivation of primary retinal microvascular pericytes ( RMPs) from mice. Methods Retinas were isolated from mice following with mechanical morcel,enzymatic digestion and filtration. The retinal fragments were incubated with low glucose DMEM with 20％ fetal bovine serum after 24 hours pre-incubation. Differential digestion was used for purification of primary RMPs. Morphological examination of cells was performed by phase contrast microscopy, and further characterization was analyzed by immunocytochemistry. Functional assay was evaluated by the pericytes-endothelial cells ( ECs) co-culture system. The treatment and use of experimental animals followed the regulations on the administration of experimental animals promulgated by the state science and technology commission. Results Cells migrated out of fragments after 24 hours of incubation, and developed into small or large colonies gradually. The cells and their subpassages presented typical pericyte morphology with large irregular triangular cell bodies and multiple long processes. No contact inhibition was observed. Most cells uniformly expressed the cellular markers α-smooth muscle actin (α-SMA) and platelet-derived growth factor receptor-β( PDGFR-β) ,a few cells expressed the cellular markers glial fibrillary acidic protein ( GFAP) ,but no cell expressed von Willebrand factor ( vWF) . The purity rate of RMPs was up to 97％. In the co-culture system,RMPs directly contacted with ECs to form the capillary-like cords in vitro. Conclusions A simple method for the isolation, purification cultivation of mouse RMPs is established, and active RMPs can be readily obtained by this method.

Proteomic research of human retinal microvascular pericytes stimulated with high glucose / 中华实验眼科杂志

Objective To determine the changes of protein expressions in human retinal microvascular pericytes ( HRMPCs) stimulated with high glucose by using quantitative proteomics, which provides new clues for future investigation of diabetic retinopathy ( DR) . Methods HRMPCs were divided into two groups. The cells in control group were cultured in DMEM basic medium with 25 mmol/L glucose,while the cells in high glucose group were cultured in DMEM medium with 35 mmol/L glucose. The amount of living cells was measured by cell counting kit-8(CCK-8). The proteins were collected from the two groups and then were digested with trypsin. Peptides of 2μg were injected into the time of flight-mass spectrometer and the acquisition mode was DDA. The results were further analyzed using bioinformatics software. Results CCK-8 results showed that the absorbance ( A450 ) of HRMPCs in high glucose group was 0. 75±0. 04,which was significantly lower than 0. 91±0. 05 in control group (t=5. 784,P=0. 0002). In total,1972 proteins were identified and 54 of them were significantly different between the two groups (fold change >1. 5). Among them,13 proteins were up-regulated,including CTNNB1 and CTBP2;while 41 proteins were down-regulated,including SQSTM1 and HMGCS1. The differentially expressed proteins were mainly involved in citric acid cycle and aerobic respiration. Conclusions The expressions of many proteins in HRMPCs change under the stimulation of high glucose,which may influence the respiration and the ATP production of cells and eventually induce the loss of pericyte.