<i>rd1 </i>Mouse Retina Shows Imbalance in Cellular Distribution and Levels of TIMP-1/MMP-9, TIMP-2/MMP-2 and Sulfated Glycosaminoglycans

Abstract

Background: The rd1 mouse retina displays fast degeneration of photoreceptors resulting in a depletion of almost all rod photoreceptors by postnatal day 21 (PN21). To evaluate the role of proteinases in the pathophysiology of this animal model of retinitis pigmentosa, C3H rd1 and congenic wild-type (wt) mice retinas were analyzed. Material and Methods: The cellular localization and levels of proteins, matrix metalloproteinases (MMPs), their endogenous inhibitors (TIMPs), total sulfated glycosaminoglycans (sGAG) and nature of saccharides in rd1 and wt retinal extracts were compared. Results: MMP-2/TIMP-2 and MMP-9/TIMP-1 were predominantly localized in the interphotoreceptor matrix (IPM) of both genotypes, but MMP-2/TIMP-2 also appeared in the Müller cell fibers of rd1 retina. In rd1 retinal extracts the levels of total proteins were lower and those of active MMP-9, MMP-2, TIMP-1 and total sGAG were higher than those of wt extracts. Despite an increase in TIMP-1, active MMP-9/MMP-2 were disproportionately elevated in rd1 compared to wt retina. With increasing age, MMPs in wt retinas were decreased but were increased in rd1. The sialylation of proteoglycans in PN2 and PN7 rd1 retinas was lower, and galactosylation was higher than that in wt retinas. Conclusions: MMP-9/MMP-2 and TIMP-1/TIMP-2 are associated with IPM, possibly after secretion by retinal pigmented epithelial cells. In degenerating rd1 retina, MMP-2/TIMP-2 are associated with the Müller cell fibers, which apparently play a central role in modifying the balance between MMPs and TIMPs. Elevated sGAG and proteolysis due to an imbalance in the levels of TIMPs and active MMP-9/MMP-2 in rd1 retina possibly contribute to retinal degeneration in the rd1 mouse.

Potential regulatory relationship between the nested gene DDC8 and its host gene tissue inhibitor of metalloproteinase-2

“…Both genes showed similar distributions in the retina, including abundant expression in the outer plexiform layer with lesser expression in the ganglion cell layer (Fig. 5A a,b ), confirming previous reports of TIMP-2 immunoreactivity in the interphotoreceptor matrix and Müller glia (1,22). In contrast, expression in the hippocampus and cerebral cortex were remarkably different.…”

Changes in Adeno-Associated Virus-Mediated Gene Delivery in Retinal Degeneration

“…Data from our laboratory show that specific enzymatic digestion of the inner limiting membrane allows for AAV-mediated expression in the outer retina and RPE (Dalkara et al, 2009). Studies have shown that active matrix metalloproteinase-9 (MMP-9) levels are elevated in the retina during degeneration (Ahuja et al, 2006), causing laminin degradation at the ganglion cell layer=ILM (Zhang et al, 2004). These studies suggest that the ILM is a barrier to AAV infection and a region of the retina that could undergo great changes during retinal degeneration, perhaps opening access to deeper AAV penetration and transduction.…”

Lectin Microarray Profiling and Relative Quantification of Glycome Associated With Proteins of Neonatalwtandrd1Mice Retinae

“…Neonatal rd1 mouse retina shows increased activities of protein kinase C, matrix metallo-proteinases (MMPs), cathepsins, modification and accumulation of fragmented proteoglycans, rapid loss of approximately 90% of the rod photoreceptors between the age of postnatal day 10 (PN10) and PN21, leading to the degeneration of retina. [1][2][3] In mammalian cells, N-/O-linked glycans or O-linked GlcNAc monomers are conjugated respectively to plasma membrane, extracellular matrix (ECM), and nucleocytoplasmic proteins at asparagine/threonine/serine and threonine/serine residues. Collectively, glycans comprise the glycome, which is diverse, cell-/tissue-type specific and influences cellular/metabolic processes.…”

“…[4][5][6][7][8][9][10] Glycans are implicated in the retinal development, regeneration, and physiopathologic processes due to their association with a variety of intra-and extracellular proteins. 3,9,10 During the last 30 years, static glycans associated with glycoproteins/ proteoglycans of retina of different species have been studied qualitatively by lectin-based low throughput immunohistochemical and blotting techniques. Profiling and relative quantification of the dynamic retinal glycome is crucial to understand its role in the regulation of structure and function of retinal proteins.…”

“…An aberrant glycosylation of such proteins in mutant mice adversely affects the structure and function of retina. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] This has remained undetermined due to lack of relevant technologies. Since 2005, high throughput lectin microarray technique involving the use of large numbers of lectins of high purity and well defined specificities became available for differential profiling and relative quantification of the glycome associated with complex biological samples.…”