Macroglia-derived thrombospondin 2 regulates alterations of presynaptic proteins of retinal neurons following elevated hydrostatic pressure

Abstract

Many studies on retinal injury and repair following elevated intraocular pressure suggest that the survival ratio of retinal neurons has been improved by various measures. However, the visual function recovery is far lower than expected. The homeostasis of retinal synapses in the visual signal pathway is the key structural basis for the delivery of visual signals. Our previous studies found that complicated changes in the synaptic structure between retinal neurons occurred much earlier than obvious degeneration of retinal ganglion cells in rat retinae. The lack of consideration of these earlier retinal synaptic changes in the rescue strategy may be partly responsible for the limited visual function recovery with the types of protective methods for retinal neurons used following elevated intraocular pressure. Thus, research on the modulatory mechanisms of the synaptic changes after elevated intraocular pressure injury may give new light to visual function rescue. In this study, we found that thrombospondin 2, an important regulator of synaptogenesis in central nervous system development, was distributed in retinal macroglia cells, and its receptor α2δ-1 was in retinal neurons. Cell cultures including mixed retinal macroglia cells/neuron cultures and retinal neuron cultures were exposed to elevated hydrostatic pressure for 2 h. The expression levels of glial fibrillary acidic protein (the marker of activated macroglia cells), thrombospondin 2, α2δ-1 and presynaptic proteins were increased following elevated hydrostatic pressure in mixed cultures, but the expression levels of postsynaptic proteins were not changed. SiRNA targeting thrombospondin 2 could decrease the upregulation of presynaptic proteins induced by the elevated hydrostatic pressure. However, in retinal neuron cultures, elevated hydrostatic pressure did not affect the expression of presynaptic or postsynaptic proteins. Rather, the retinal neuron cultures with added recombinant thrombospondin 2 protein upregulated the level of presynaptic proteins. Finally, gabapentin decreased the expression of presynaptic proteins in mixed cultures by blocking the interaction of thrombospondin 2 and α2δ-1. Taken together, these results indicate that activated macroglia cells may participate in alterations of presynaptic proteins of retinal neurons following elevated hydrostatic pressure, and macroglia-derived thrombospondin 2 may modulate these changes via binding to its neuronal receptor α2δ-1.

Pin1 Promotes Regulated Necrosis Induced by Glutamate in Rat Retinal Neurons via CAST/Calpain2 Pathway

“…All experimental procedures used in the present study were approved by the Ethics Committee of the 3rd Xiangya Hospital of Central South University in accordance with the National Institutes of Health (NIH) Guidelines for the Care and Use of Laboratory Animals. Primary retinal neuronal cultures were prepared from 1-day-old neonatal Sprague-Dawley (SD) rat as described previously ( Li et al, 2016 ; Morgan-Warren et al, 2016 ; Wang S. et al, 2017 ). In brief, the eyes were removed aseptically, and then the corneas, crystalline lens, and pigment epithelium layer were removed, leaving the retinae.…”

“…Because both ionotropic and metabotropic glutamate receptors are exist in primary retinal neurons and retinal neuron lines ( Connaughton, 1995 ; Otori et al, 1998 ; Hack et al, 1999 ; Pang et al, 1999 ), which means the overstimulation of glutamate receptors could cause the increase of calcium influx and the followed apoptosis and necrosis. We have established the primary retinal cultures (the purity is over 90%) ( Li et al, 2016 ; Wang S. et al, 2017 ), which is understandable to be used in the next experiments ( Petegnief et al, 2001 ; Oliveira et al, 2011 ; Miao et al, 2012 ; Tan et al, 2014 ; Morgan-Warren et al, 2016 ).…”

High hydrostatic pressure induces apoptosis of retinal ganglion cells via regulation of the NGF signalling pathway

“…A growing number of studies have demonstrated that increased apoptosis, proliferation and migration exist in cells treated with elevated HP (20,21). Thus, cells exposed to elevated HP may generally function as an in vitro model of glaucomatous RGC apoptosis, as performed in the present study (22). Although Osborne et al (23) revealed that elevation of HP did not cause apoptosis in human RGCs cultured at 60 mmHg for 24 h, this difference may be associated with the speed of pressure fluctuations (24).…”

Phosphatidylserine-microbubble targeting-activated microglia/macrophage in inflammation combined with ultrasound for breaking through the blood–brain barrier

“…4 b). It has been reported that activated M/M with dendritic morphology is easy to recruit and travel and further shows active inflammatory response in ischemic area immediately after ischemia [ 15 ]. To track the change of activated M/M in the long term, rats were sacrificed for its brain needed in immunofluorescence experiments at 1, 7, 14, and 21 days post IR (Fig.…”