Janet C. Blanks
Florida Atlantic University
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Featured researches published by Janet C. Blanks.
Investigative Ophthalmology & Visual Science | 2011
Howard Prentice; Manas R. Biswal; C. Kathleen Dorey; Janet C. Blanks
PURPOSE Retinal Müller cells span the retina and secrete several trophic factors and represent the functional link between blood vessels and neurons, making them attractive targets for gene therapy. Therefore, a hypoxia-regulated, retinal glial cell-specific vector was constructed and tested for its response to hypoxia. METHODS A hybrid promoter containing domains of human glial fibrillary acidic protein (GFAP) and several hypoxia-responsive and aerobically silenced elements (HRSE) was incorporated separately into plasmid vectors for generation of self-complementary adeno-associated virus. Müller cells trasfected with plasmids or virus were compared with other cell lines using standard METHODS The mouse model of oxygen-induced retinopathy (OIR) was used to analyze retinas from mice exposed to high oxygen or room air to evaluate the induction of the regulated promoter. RESULTS The regulated promoter was silenced under aerobic conditions in comparison with unregulated promoter in Müller cells. Hypoxia induced a 12-fold and 16-fold increase in promoter activity in primary Müller cells and human Müller cell lines, respectively. In the OIR model, intravitreal injection of the regulated promoter at postnatal day 7 (P7) resulted in high levels of green fluorescent protein expression only in retinal Müller cells at P17. GFP expression was absent in retinas of mice only exposed to room air. In vivo studies confirm normoxia silencing, hypoxic induction, and cell specificity of the regulated promoter in the mouse retina. CONCLUSIONS This hypoxia-regulated, retinal glial cell-specific AAV vector provides a platform for gene therapy within regions of retinal hypoxia which are found in diabetic retinopathy and age-related macular degeneration.
Proceedings of the National Academy of Sciences of the United States of America | 2014
Arunodoy Sur; Shailaja Kesaraju; Howard Prentice; Kasirajan Ayyanathan; Diane Baronas-Lowell; Danhong Zhu; David R. Hinton; Janet C. Blanks; Herbert Weissbach
Significance Oxidative stress-induced damage to retinal pigmented epithelial (RPE) cells is implicated in the progression of age-related macular degeneration (AMD), which is one of the primary causes of vision loss in the elderly. The present studies show that sulindac, a known nonsteroidal antiinflammatory drug, can protect an established RPE cell line, low-passage human fetal RPE, and polarized primary human fetal RPE cells against oxidative damage. The results with the RPE cell line indicate that the protective response is similar to that seen with ischemic preconditioning. Our results suggest that preventing oxidative damage in RPE cells by this drug-induced protective mechanism could be an inexpensive and relatively nontoxic therapeutic approach for AMD treatment. The retinal pigmented epithelial (RPE) layer is one of the major ocular tissues affected by oxidative stress and is known to play an important role in the etiology of age-related macular degeneration (AMD), the major cause of blinding in the elderly. In the present study, sulindac, a nonsteroidal antiinflammatory drug (NSAID), was tested for protection against oxidative stress-induced damage in an established RPE cell line (ARPE-19). Besides its established antiinflammatory activity, sulindac has previously been shown to protect cardiac tissue against ischemia/reperfusion damage, although the exact mechanism was not elucidated. As shown here, sulindac can also protect RPE cells from chemical oxidative damage or UV light by initiating a protective mechanism similar to what is observed in ischemic preconditioning (IPC) response. The mechanism of protection appears to be triggered by reactive oxygen species (ROS) and involves known IPC signaling components such as PKG and PKC epsilon in addition to the mitochondrial ATP-sensitive K+ channel. Sulindac induced iNOS and Hsp70, late-phase IPC markers in the RPE cells. A unique feature of the sulindac protective response is that it involves activation of the peroxisome proliferator-activated receptor alpha (PPAR-α). We have also used low-passage human fetal RPE and polarized primary fetal RPE cells to validate the basic observation that sulindac can protect retinal cells against oxidative stress. These findings indicate a mechanism for preventing oxidative stress in RPE cells and suggest that sulindac could be used therapeutically for slowing the progression of AMD.
Investigative Ophthalmology & Visual Science | 2014
Manas R. Biswal; Howard Prentice; C. Dorey; Janet C. Blanks
PURPOSE Müller cells, the major glial cell in the retina, play a significant role in retinal neovascularization in response to tissue hypoxia. We previously designed and tested a vector using a hypoxia-responsive domain and a glial fibrillary acidic protein (GFAP) promoter to drive green fluorescent protein (GFP) expression in Müller cells in the murine model of oxygen-induced retinopathy (OIR). This study compares the efficacy of regulated and unregulated Müller cell delivery of endostatin in preventing neovascularization in the OIR model. METHODS Endostatin cDNA was cloned into plasmids with hypoxia-regulated GFAP or unregulated GFAP promoters, and packaged into self-complementary adeno-associated virus serotype 2 vectors (scAAV2). Before placement in hyperoxia on postnatal day (P)7, mice were given intravitreal injections of regulated or unregulated scAAV2, capsid, or PBS. Five days after return to room air, on P17, neovascular and avascular areas, as well as expression of the transgene and vascular endothelial growth factor (VEGF), were compared in OIR animals treated with a vector, capsid, or PBS. RESULTS The hypoxia-regulated, glial-specific, vector-expressing endostatin reduced neovascularization by 93% and reduced the central vaso-obliteration area by 90%, matching the results with the unregulated GFAP-Endo vector. Retinas treated with the regulated endostatin vector expressed substantial amounts of endostatin protein, and significantly reduced VEGF protein. Endostatin production from the regulated vector was undetectable in retinas with undamaged vasculature. CONCLUSIONS These findings suggest that the hypoxia-regulated, glial cell-specific vector expressing endostatin may be useful for treatment of neovascularization in proliferative diabetic retinopathy.
Experimental Eye Research | 2009
Rainald Schmidt-Kastner; Pawel Kreczmanski; Markus N. Preising; Roselie M.H. Diederen; Christoph Schmitz; Danielle Reis; Janet C. Blanks; C. Kathleen Dorey
Wolfram syndrome 1 (WFS1, OMIM 222300), a rare genetic disorder characterized by optic nerve atrophy, deafness, diabetes insipidus and diabetes mellitus, is caused by mutations of WFS1, encoding WFS1/wolframin. Non-syndromic WFS1 variants are associated with the risk of diabetes mellitus due to altered function of wolframin in pancreatic islet cells, expanding the importance of wolframin. This study extends a previous report for the monkey retina, using immunohistochemistry to localize wolframin on cryostat and paraffin sections of human retina. In addition, the human retinal pigment epithelial (RPE) cell line termed ARPE-19 and retinas from both pigmented and albino mice were studied to assess wolframin localization. In the human retina, wolframin was expressed in retinal ganglion cells, optic axons and the proximal optic nerve. Wolframin expression in the human retinal pigment epithelium (RPE) was confirmed with intense cytoplasmic labeling in ARPE-19 cells. Strong labeling of the RPE was also found in the albino mouse retina. Cryostat sections of the mouse retina showed a more extended pattern of wolframin labeling, including the inner nuclear layer (INL) and photoreceptor inner segments, confirming the recent report of Kawano et al. [Kawano, J., Tanizawa, Y., Shinoda, K., 2008. Wolfram syndrome 1 (Wfs1) gene expression in the normal mouse visual system. J. Comp. Neurol. 510, 1-23]. Absence of these cells in the human specimens despite the use of human-specific antibodies to wolframin may be related to delayed fixation. Loss of wolframin function in RGCs and the unmyelinated portion of retinal axons could explain optic nerve atrophy in Wolfram Syndrome 1.
Investigative Ophthalmology & Visual Science | 2008
Michele Nachman-Clewner; Frank J. Giblin; C. Kathleen Dorey; Robert H. I. Blanks; Loan Dang; Christopher J. Dougherty; Janet C. Blanks
PURPOSE Metallothioneins (MTs) in the brain and retina are believed to bind metals and reduce free radicals, thereby protecting neurons from oxidative damage. This study was undertaken to investigate whether retinal photoreceptor (PR) cells lacking MTs are more susceptible to hyperbaric oxygen (HBO)-induced cell death in vivo. METHODS Wild-type (WT) and MT-knockout (MT-KO) mice lacking metallothionein (MT)-1 and MT-2 were exposed to three atmospheres of 100% oxygen for 3 hours, 3 times per week for 1, 3, or 5 weeks. The control animals were not exposed. Histologic analysis of PR viability was performed by counting rows of nuclei in the outer nuclear layer (ONL). Ultrastructure studies verified PR damage. RESULTS HBO exposure produced a major loss of PR cells in the central retinas of WT and MT-KO mice, with no effect on the peripheral retina even at the longest (5 weeks) exposures. The degree of PR damage and cell death increased with duration of HBO exposure. One week of HBO exposure was insufficient to cause PR death, but tissue damage was observed in the inner and outer segments. At 3 weeks, the rows of PR nuclei in the central retina were significantly reduced by 38% in WT and 28% in MT-KO animals. At 5 weeks, PR loss was identical in WT (34%) and MT-KO (34%) animals and was comparable to that in WT at 3 weeks. CONCLUSIONS The data suggest that MT-1 and -2 alone are not sufficient for protecting PRs against HBO-induced cell death. The selective degeneration of central PRs may provide clues to mechanisms of oxidative damage in retinal disease.
Advances in Experimental Medicine and Biology | 2012
George W. Smith; C. Kathleen Dorey; Howard Prentice; Janet C. Blanks
Age-related macular degeneration (AMD) is the leading cause of blindness in the western world for people over 60 years of age. The most severe pathological event of AMD is choroidal neovascularization (CNV), the process of new vessel formation emerging from the choroid. The new vessels extend into the normally avascular photoreceptor cell layer, where they leak fluid and cause photoreceptor cell death. CNV is thought to be initiated by hypoxia and chronic inflammation, which occur due to abnormal, age-related changes within the retinal pigmented epithelium (RPE). These events cause increased expression of the angiogenic protein vascular endothelial growth factor (VEGF) via hypoxia-inducible factor-1 (HIF-1), a transcription factor that is vital in regulation of cellular responses to hypoxic and inflammatory conditions. Increased VEGF signaling stimulates proliferation and migration of vascular endothelial cells and facilitates the neovascular process.
Archive | 2012
Manas R. Biswal; Howard Prentice; Janet C. Blanks
Gliomas are the most common brain tumor in the central nervous system (CNS). The majority of malignant gliomas arise from neoplastic transformation of resident astrocytes. Gliomas are very aggressive tumors since they are characterized by widespread invasion of brain tissue. The exact pathogenesis and underlying mechanisms for glioma cell infiltration are currently unclear. Cell-cell interaction and tissue microenvironment play an important role in tumor progression leading to modification and infiltration of surrounding tissue. The hypoxic microenvironment contributes to abnormal neovascularization of the glioma.
Molecular Vision | 2006
Ji-jing Pang; Cheng M; Haire Se; Edward D. Barker; Planelles; Janet C. Blanks
Experimental Eye Research | 2004
Ji-jing Pang; Mei Cheng; Douglas Stevenson; Melvin D. Trousdale; C. Kathleen Dorey; Janet C. Blanks
Molecular Vision | 2008
Rainald Schmidt-Kastner; Hideo Yamamoto; Duco I. Hamasaki; Hiroko Yamamoto; Jean Marie Parel; Christoph Schmitz; C. Kathy Dorey; Janet C. Blanks; Markus N. Preising