Induction of vitronectin and integrin alphav in the retina after optic nerve injury.
OBJECTIVE
Vitronectin is a secreted glycoprotein present in blood plasma and is present in the extracellular matrix of many tissues. It was found in the retinal cDNA library that contains genes whose expression is upregulated after optic nerve injury in a previous study. The purpose of this study was to assess the temporal and spatial changes in expression of vitronectin and integrin alphav in the retina following optic nerve injury.


METHODS
Adult Balb/c mice underwent crush of the optic nerve in one eye only. RT-PCR was used to determine the temporal expression of vitronectin mRNA in the retina after injury. In addition, expression at the protein level in the retina and the optic nerve of vitronectin and its major receptor subunit, integrin alphav, was analyzed by immunohistochemistry.


RESULTS
Upregulation of vitronectin mRNA in the retina was detected at one day after injury, peaking at three days, and maintained up to one week. An elevated expression of vitronectin protein was also observed in the inner retina, optic nerve head, and the optic nerve after nerve crush. In the inner retina, the increased expression of vitronectin was found in retinal ganglion cells (RGCs) and its surrounding extracellular matrix. Expression of integrin alphav was also increased in the RGC layer and in the glial cells of the nerve head and the crush site.


CONCLUSIONS
As vitronectin is an extracellular protein that can support cell attachment and promote neurite extension, elevated expression of vitronectin and its receptor may facilitate axonal regeneration following injury. We propose that treatment sustaining secretion of endogenous vitronectin or direct application of exogenous vitronectin may be a method to augment regeneration of the severed optic axons.
Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan. agwang@vghtpe.gov.tw
An-Guor
AG
Wang
May-Yung
MY
Yen
Wen-Ming
WM
Hsu
Ming-Ji
MJ
Fann
D000818:Animals; D005109:Extracellular Matrix / Q000378:metabolism; D007150:Immunohistochemistry; D039564:Integrin alphaV / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D009409:Nerve Crush; D009457:Neuroglia / Q000378:metabolism; D009900:Optic Nerve / Q000378:metabolism; D020221:Optic Nerve Injuries / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014018:Tissue Distribution; D015854:Up-Regulation; D019096:Vitronectin / Q000096:biosynthesis* / Q000235:genetics
D039564:Integrin alphaV; D012333:RNA, Messenger; D019096:Vitronectin