Biology subjects

Geisert, E. E.

Publications and source records attributed to Geisert, E. E..

9 recordsLinked to original sources

bioRxiv2026

Mouse Predation is Dependent on a Population of POU6F2-Positive Retinal Ganglion Cells

The contribution of retinal ganglion cells (RGCs) subtypes to visually guided behavior continues to be an active area of research. We identify POU6F2-expressing RGCs essential for binocular predatory behavior. The POU6F2 RGCs are ON-OFF direction-selective RGCs that are vulnerable to glaucomatous injury. In Pou6f2 knockout (Pou6f2-/-) mice, there is a 12% loss of RGCs, and these cells are the POU6F2-expressing RGCs. Functionally, Pou6f2-/-mice exhibited profound deficits in contrast sensitivity. In this study we found a deficit in the ability of Pou6f2-/- mice to perform a binocularly driven cricked predation test. Wildtype mice detect and capture the cricket rapidly; while, both Pou6f2-/- mice and mice with one optic nerve crushed, required significant longer times to complete the task. After optic nerve crush no further impairment in performance is seen in the knockout mouse. These data demonstrate that the POU6F2-positive RGCs are essential for this binocularly driven behavior.

neuroscience↗

bioRxiv2025

Mechanistic insights into glucocorticoid-induced ocular hypertension using differences in mouse strain responsiveness

Glucocorticoids (GCs) are widely prescribed anti-inflammatory agents. Unfortunately, many people experience negative side-effects associated with long term GC therapy, developing GC-induced ocular hypertension (GC-OHT), which can lead to secondary glaucoma. Approximately, 40% of the treated individuals are susceptible to GC-OHT. Seventy years since this discovery, the molecular mechanisms underlying GC-OHT remain unclear. We previously developed a mouse model of GC-OHT delivering the potent GC dexamethasone (DEX) and observed strain-specific disparities in the development of GC-OHT. We now compare phenotypic and transcriptomic differences between five genetically distinct inbred mouse strains to identify biomarkers of GC susceptibility, and to better understand the molecular mechanisms of GC-OHT. Like humans, mouse strains differ in their ability to develop GC-OHT. Phenotypic characterization revealed that C57BL/6J and C3H/HeJ mice are GC responders and more susceptible to develop GC-OHT. DEX treatment in these strains led to elevated IOP compared to the GC non-responder strains DBA/2J.Gpnmb+, 129P3/J, and BALB/cJ. Transcriptomic analysis of responder and non-responder mouse strains revealed novel trabecular meshwork (TM) biomarkers of GC-OHT susceptibility involving enrichment of molecular pathways unique to this response. Our study identifies putative mechanisms underlying GC-OHT and provides insight into the pathogenesis of the clinically similar but more prevalent primary open-angle glaucoma.

pathology↗

bioRxiv2024

Oral supplementation with Nicotinamide Riboside treatment protects RGCs in DBA/2J mouse model

PurposeThe aim of this study was to test whether oral administration of nicotinamide riboside (NR), the nicotinamide adenine dinucleotide (NAD+) precursors, protect retina ganglion cells (RGCs) from neurodegeneration in DBA/2J (D2) mice, which is a widely used mouse model of age-related inherited glaucoma. MethodOral NR or NAM administration (NR low dose: 1150mg/kg; NR high dose: 4200mg/kg; NAM low dose group: 500mg/kg; NAM high dose: 2000mg/kg of body weight per day) essentially started when D2 mice were 4 or 9 months old and continued up to 12 months old. Control cohort identically received food/water without NAM or NR. Intraocular pressure (IOP) was measured every month until experiment completion. Pattern electroretinography (PERG) was recorded. Retinas were harvested for whole mount immunofluorescence staining with RGCs marker Brn3a and imaged by fluorescent confocal microscopy. Optic nerves were harvested for axon staining and quantification. Retinal NAD+ levels were enzymatically assayed. ResultsNR oral supplementary treatment started at 4 months old robustly increased retinal NAD+ levels in D2 mice (NRHigh vs. vehicle: 273.7{+/-}23.59% vs. 108.70{+/-}12.10%, p<0.001). In aged vehicle group (12 months old), there was significantly diminution of the P1 and N2 components of PERG response compare with naive group (naive vs. vehicle: P1: 7.82{+/-} 0.70uV vs 1.63{+/-} 0.17uV, p<0.0001; N2: -13.29{+/-} 0.83uV vs. -3.22{+/-} 0.27uV, p<0.0001; Kruskal-Wallis test with Dunn s multiple comparison test). NR treatment preserved aged D2 visual function when mice were 9 and 12 months old. In addition, long-term NR high dose treatment significantly protected against total RGCs loss and optic nerve atrophy (RGC: NRHigh vs. vehicle: 1412{+/-}62.00vs 475.2{+/-}94.68 cells/field, p<0.00001; axon numbers: NRHigh vs. vehicle: 23990{+/-}1159 vs 8573{+/-}1160, n=41-53, p<0.0001). Furthermore, long-term NR supplementation prevent iris depigmentation and delayed IOP elevation. ConclusionNR oral supplementary treatment significantly preserved RGC and axon numbers, potentially preserves retinal function via elevated retinal NAD+ level in aged D2 mice. Interestingly, NR treatment also prevented iris atrophy, delayed IOP elevation associated with this glaucoma model. NR oral supplementation thus treated several aspects of murine pigment dispersion glaucoma. Given parallels between this model and glaucoma in human, out data indicate that NR is worth exploring as a therapeutic candidate in treatment of glaucoma.

neuroscience↗

bioRxiv2024

Dnajc3 (HSP40) Modulates Axon Regeneration in the Mouse Optic Nerve

A forward genetics approach was used to identify genomic elements enhancing axon regeneration in the BXD recombinant mouse strains. Axon regeneration was induced by knocking down Pten in retinal ganglion cells (RGCs) using adeno-associated virus (AAV) to deliver an shRNA followed by an intravitreal injection of Zymosan with CPT-cAMP that produced a mild inflammatory response. RGC axons were damaged by optic nerve crush (ONC). Following a 12-day survival period, regenerating axons were labeled by intravitreal injection of Cholera Toxin B (CTB) conjugated with Alexa Fluor 647. Two days later, labeled axons within the optic nerve were examined to determine the number of regenerating axons and the distance they traveled down the optic nerve. The analysis revealed a surprising difference in the amount of axonal regeneration across all 33 BXD strains. There was a 7.5-fold difference in the number of regenerating axons and a 4-fold difference in distance traveled by regenerating axons. These data were used to generate an integral map defining genomic loci modulating the enhanced axonal regeneration. A quantitative trait locus modulating axon regeneration was identified on Chromosome 14 (115 to 119 Mb). Within this locus were 16 annotated genes. Subsequent testing revealed that one candidate gene, Dnajc3, modulates axonal regeneration. Dnajc3 encodes Heat Shock Protein 40 (HSP40), which is a molecular chaperone. Knocking down Dnajc3 in the high regenerative strain (BXD90) led to a decreased regeneration response, while overexpression of Dnajc3 in a low regenerative strain (BXD34) resulted in an increased regeneration response. These findings suggest that Dnajc3 not only increases the number of regenerating axons, it also increases the distance those axons travel. This may prove to be critical for functional recovery in large mammals, where the distance axons travel to their target is considerably longer than that of the mouse. Thus, Dnajc3 may play a critical role for functional recovery in humans by increasing the number of regenerating axons and the distance the regenerating axons travel.

neuroscience↗

bioRxiv2020

POU6F2 Positive Retinal Ganglion Cells a Novel Group of ON-OFF Directionally Selective Subtypes in the Mouse Retina.

PurposePreviously we identified POU6F2 as a genetic link between central corneal thickness (CCT) and risk of open-angle glaucoma. The present study is designed to characterize the POU6F2-positive retinal ganglion cells (RGCs). MethodsThe Thy1-YFP-H mouse was used to identify the structure of POU6F2-positive RGCs in the retina. In the retina of the Thy1-YFP-H mouse approximately 3% of the RGCs were labeled with yellow fluorescent protein. These retinas were stained for POU6F2 to identify the morphology of the POU6F2 subtypes in 3D reconstructions of the labeled RGCs. Multiple retinal cell markers were also co-stained with POU6F2 to characterize the molecular signature of the POU6F2-positive RGCs. DBA/2J glaucoma models were used to test the role of POU6F2 in injury. ResultsIn the retina POU6F2 labels 32.9% of the RGCs in the DBA/2J retina (16.1% heavily and 16.8% lightly labeled). In 3D constructions of Thy1-YFP-H positive RGCs, the heavily labeled POU6F2-positive cells had dendrites in the inner plexiform layer that were bistratified and appeared to be ON-OFF directionally selective cells. The lightly labeled POU6F2 RGCs displayed 3 different dendritic distributions, with dendrites in the ON sublaminae only, OFF sublaminae only, or bistratified. The POU6F2-positive cells partially co-stained with Cdh6. The POU6F2-positive cells do not co-stain with CART and SATB2 (markers for ON-OFF directionally selective RGC), SMI32 (a marker for alpha RGCs), or ChAT and GAD67(markers for amacrine cells). The POU6F2-positive cells were sensitive to injury. In DBA/2J glaucoma model, at 8 months of age there was a 22% loss of RGCs (labeled with RBPMS) while there was 73% loss of the heavily labeled POU6F2 RGCs. ConclusionsPOU6F2 is a marker for a novel group of RGC subtypes that are ON-OFF directionally selective RGCs that are sensitive to glaucomatous injury.

genetics↗

bioRxiv2017

Genomic Locus Modulating Corneal Thickness in the Mouse Identifies POU6F2 as a Potential Risk of Developing Glaucoma

Purpose: Central corneal thickness (CCT) is one of the most heritable ocular traits and it is also a phenotypic risk factor for primary open angle glaucoma (POAG). The present study uses the BXD Recombinant Inbred (RI) strains to identify novel quantitative trait loci (QTLs) modulating CCT in the mouse with the potential of identifying a molecular link between CCT and risk of developing POAG.\n\nMethods: The BXD RI strain set was used to define mammalian genomic loci modulating CCT, with a total of 818 corneas measured from 61 BXD RI strains (between 60-100 days of age). The mice were anesthetized and the eyes were positioned in front of the lens of the Phoenix Micron IV Image-Guided OCT system or the Bioptigen OCT system. CCT data for each strain was averaged and used to identify quantitative trait loci (QTLs) modulating this phenotype using the bioinformatics tools on GeneNetwork (www.genenetwork.org). The candidate genes and genomic loci identified in the mouse were then directly compared with the summary data from a human primary open-angle glaucoma (POGA) genome wide association study (NEIGHBORHOOD) to determine if any genomic elements modulating mouse CCT are also risk factors for POAG.\n\nResults: This analysis revealed one significant QTL on Chr 13 and a suggestive QTL on Chr 7. The significant locus on Chr 13 (13 to 19 Mb) was examined further to define candidate genes modulating this eye phenotype. For the Chr 13 QTL in the mouse, only one gene in the region (Pou6f2) contained nonsynonymous SNPs. Of these five nonsynonymous SNPs in Pou6f2, two resulted in changes in the amino acid proline which could result in altered secondary structure affecting protein function. The 7 Mb region under the mouse Chr 13 peak distributes over 2 chromosomes in the human: Chr 1 and Chr 7. These genomic loci were examined in the NEIGHBORHOOD database to determine if they are potential risk factors for human glaucoma identified using meta-data from human GWAS. The top 50 hits all resided within one gene (POU6F2), with the highest significance level of p = 10-6 for SNP rs76319873. POU6F2 is found in retinal ganglion cells and in corneal limbal stem cells. To test the effect of POU6F2 on CCT we examined the corneas of a Pou6f2-null mice and the corneas were thinner than those of wild-type littermates. In addition, these POU6F2 RGCs die early in the DBA/2J model of glaucoma than most RGCs.\n\nConclusions: Using a mouse genetic reference panel, we identified a transcription factor, Pou6f2, that modulates CCT in the mouse. POU6F2 is also found in a subset of retinal ganglion cells and these RGCs are sensitive to injury.\n\nAuthors SummaryGlaucoma is a complex group of diseases with several known causal mutations and many known risk factors. One well-known risk factor for developing primary open angle glaucoma is the thickness of the central cornea. The present study leverages a unique blend of systems biology methods using BXD recombinant inbred mice and genome-wide association studies from humans to define a putative molecular link between a phenotypic risk factor (central corneal thickness) and glaucoma. We identified a transcription factor, POU6F2, that is found in the developing retinal ganglion cells and cornea. POU6F2 is also present in a subpopulation of retinal ganglion cells and in stem cells of the cornea. Functional studies reveal that POU6F2 is associated the central corneal thickness and with susceptibility of retinal ganglion cells to injury.

genetics↗

bioRxiv2017

Genomic Loci Modulating Retinal Ganglion Cell Death Following Elevated IOP in the Mouse

The present study was designed to identify genomic loci modulating the susceptibility of retinal ganglion cells (RGC) to elevated intraocular pressure (IOP) in the BXD recombinant inbred mouse strain set. IOP was elevated by injecting magnetic microspheres into the anterior chamber and blocking the trabecular meshwork using a handheld magnet to impede drainage. The IOP was then measured over the next 21 days. Only animals with IOP greater than 25 mmHg for two consecutive days or an IOP above 30 mmHg on a single day after microsphere-injection were used in this study. On day 21, mice were sacrificed and the optic nerve was processed for histology. Axons were counted for both the injected and the control eye in 49 BXD strains, totaling 181 normal counts and 191 counts associated with elevated IOP. The axon loss for each strain was calculated and the data were entered into genenetwork.org. The average number of normal axons in the optic nerve across all strains was 54,788 {+/-} 16% (SD), which dropped to 49,545 {+/-} 20% in animals with artificially elevated IOP. Interval mapping demonstrated a relatively similar genome-wide map for both conditions with a suggestive Quantitative Trait Locus (QTL) on proximal Chromosome 3. When the relative axon loss was used to generate a genome-wide interval map, we identified one significant QTL (p<0.05) on Chromosome 18 between 53.6 and 57 Mb. Within this region, the best candidate gene for modulating axon loss was Aldh7a1. Immunohistochemistry demonstrated ALDH7A1 expression in mouse RGCs. ALDH7A1 variants were not significantly associated with glaucoma in the NEIGHBORHOOD GWAS dataset, but this enzyme was identified as part of the butanoate pathway previously associated with glaucoma risk. Our results suggest that genomic background influences susceptibility to RGC degeneration and death in an inducible glaucoma model.

genetics↗

bioRxiv2017

Genetic Locus Modulating IOP

PurposeIntraocular pressure (IOP) is the primary risk factor for developing glaucoma. The present study examines genomic contribution to the normal regulation of IOP in the mouse.\n\nMethodsThe BXD recombinant inbred (RI) strain set was used to identify genomic loci modulating IOP. We measured the IOP from 532 eyes from 34 different strains. The IOP data will be subjected to conventional quantitative trait analysis using simple and composite interval mapping along with epistatic interactions to define genomic loci modulating normal IOP.\n\nResultsThe analysis defined one significant quantitative trait locus (QTL) on Chr.8 (100 to 106 Mb). The significant locus was further examined to define candidate genes that modulate normal IOP. There are only two good candidate genes within the 6 Mb over the peak, Cdh8 (Cadherin 8) and Cdh11 (Cadherin 11). Expression analysis on gene expression and immunohistochemistry indicate that Cdh11 is the best candidate for modulating the normal levels of IOP.\n\nConclusionsWe have examined the genomic regulation of IOP in the BXD RI strain set and found one significant QTL on Chr. 8. Within this QTL that are two potential candidates for modulating IOP with the most likely gene being Cdh11.

bioinformatics↗

bioRxiv2017

The BXD Mouse Strains are a Model System for Studying Optic Nerve Regeneration

The present study is designed to identify the influences of genetic background to optic nerve regeneration using the two parental strains C57BL/6J and DBA/2J and 7 BXD recombinant inbred strains. To study regeneration in the optic nerve, Pten was knocked down in the retinal ganglion cells using AAV, and a mild inflammatory response was induced by an intravitreal injection of zymosan with CPT-cAMP, and the axons were damaged by optic nerve crush (ONC). Regenerating axons were labeled by Cholera Toxin B and quantified 14 days after ONC. The number of axons at 0.5 mm and 1 mm from the crush site were counted. In addition, we measured the distance that 5 axons had grown down the nerve and the longest distance a single axon reached. Results showed a considerable amount of differential axonal growth across all 9 BXD strains. There was a significant difference (P=0.014 Mann-Whitney U test) in the regenerative capacity in the number of axons reaching 0.5 mm from a low of 1487.6 {+/-} 264.9 axons in BXD102 to a high of 4175.8 {+/-} 648.6 axons in BXD29. There were also significant differences (P=0.014 Mann-Whitney U test) in the distance axons traveled, looking at a minimum of 5 axons with the shortest distance was 787.2 {+/-} 46.5{micro}m in BXD102 to a maximum distance of 2025.5 {+/-} 223.3{micro}m in BXD29. These results reveal that genetic background can modulate axonal regeneration and that the BXD strains are a particularly well-suited model system.

neuroscience↗