Neuroprotective Effects of Brn3b in PC12 Cells and Retinal Ganglion Cells under Glaucomatous Conditions

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dc.contributor.advisorRaghu R. Krishnamoorthy
dc.contributor.committeeMemberWeiming Mao
dc.contributor.committeeMemberJohn V. Planz
dc.creatorPhatak, Nitasha R.
dc.date.accessioned2019-08-22T21:35:28Z
dc.date.available2019-08-22T21:35:28Z
dc.date.issued2015-08-01
dc.date.submitted2015-08-17T12:36:05-07:00
dc.description.abstractGlaucoma is a group of chronic progressive optic neuropathies commonly characterized by elevated intraocular pressure (IOP) (a subset of glaucoma patients display neurodegenerative effects at ‘normal’ IOP) leading to axonal degeneration, optic nerve head cupping and apoptosis of retinal ganglion cell death (RGCs), which result in visual field defects and blindness. While there are medications available to lower IOP, there is an unmet need for neuroprotective treatments for glaucoma, since some neurodegenerative effects persist despite lowering IOP. The main focus of this study was on the class 4 POU domain transcription factor, Brn3b, which has been shown to play a key role in the development of RGCs. Two previous studies from other labs showed that a decrease in Brn3b expression occurs in animal model of glaucoma. A recent publication from our laboratory demonstrated neuroprotective effects of adeno-associated virus (AAV) mediated expression of Brn3b in a rat model of ocular hypertension. This research project identified some mechanisms of Brn3b-mediated neuroprotection in cultured PC12 cells (under the condition of hypoxia) and also in vivo in the Morrison’s model of ocular hypertension in rats. In the first part of the study, we demonstrated the effect of overexpression of Brn3b on various markers of synaptic plasticity in PC12 cells under conditions of normoxia as well as hypoxia. Immunoblot as well as immunocytochemical analyses revealed an increase in expression of neurite growth markers, GAP-43 and ac-TUBA, by Brn3b upregulation both under conditions of normoxia as well as hypoxia. . This suggests that transcription factor Brn3b has the ability to upregulate expression genes contributing to synaptic plasticity genes both under ‘normal’ conditions and during a glaucomatous insult (hypoxia). In the concluding part of this study, cell survival factors including, Bcl-2, Bcl-xL and p-AKT were studied as potential targets of Brn3b-mediated neuroprotection. Adeno-associated virus-mediated expression of Brn3b in rat eyes with elevated IOP promoted an upregulation of Bcl-2, Bcl-xL and p-AKT in RGCs, as determined by immunohistochemistry. Taken together, the evidence suggests that Brn3b has the potential to be developed as a therapeutic agent for neuroprotection during ocular neurodegenerative diseases like glaucoma.
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/20.500.12503/29444
dc.language.isoen
dc.provenance.legacyDownloads151
dc.subjectAmino Acids, Peptides, and Proteins
dc.subjectChemical Actions and Uses
dc.subjectEye Diseases
dc.subjectMedical Sciences
dc.subjectMedicine and Health Sciences
dc.subjectNervous System Diseases
dc.subjectSense Organs
dc.subjecttranscription factor Brn3b
dc.subjectglaucoma
dc.titleNeuroprotective Effects of Brn3b in PC12 Cells and Retinal Ganglion Cells under Glaucomatous Conditions
dc.typeDissertation
dc.type.materialtext
thesis.degree.departmentGraduate School of Biomedical Sciences
thesis.degree.grantorUniversity of North Texas Health Science Center at Fort Worth
thesis.degree.nameDoctor of Philosophy

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