Activation of Apoptosis in a βB1-CTGF Transgenic Mouse Model

• Main Authors: Maximilian Weiss, Sabrina Reinehr, Ana M. Mueller-Buehl, Johanna D. Doerner, Rudolf Fuchshofer, Gesa Stute, H. Burkhard Dick, Stephanie C. Joachim
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: International Journal of Molecular Sciences
• Subjects: βB1-CTGF; primary open-angle glaucoma; apoptosis; caspase 3; neurofilament H; Bax/Bcl2
• Online Access: https://www.mdpi.com/1422-0067/22/4/1997
• ISSN: 1661-6596; 1422-0067

To reveal the pathomechanisms of glaucoma, a common cause of blindness, suitable animal models are needed. As previously shown, retinal ganglion cell and optic nerve degeneration occur in βB1-CTGF mice. Here, we aimed to determine possible apoptotic mechanisms and degeneration of different retinal cells. Hence, retinae were processed for immunohistology (<i>n</i> = 5–9/group) and quantitative real-time PCR analysis (<i>n</i> = 5–7/group) in 5- and 10-week-old βB1-CTGF and wildtype controls. We noted significantly more cleaved caspase 3⁺ cells in βB1-CTGF retinae at 5 (<i>p </i>=<i> </i>0.005) and 10 weeks (<i>p </i>=<i> </i>0.02), and a significant upregulation of <i>Casp3</i> and <i>Bax</i><i>/Bcl2</i> mRNA levels (<i>p </i><<i> </i>0.05). Furthermore, more terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL⁺) cells were detected in transgenic mice at 5 (<i>p </i>=<i> </i>0.03) and 10 weeks (<i>p </i>=<i> </i>0.02). Neurofilament H staining (<i>p </i>=<i> </i>0.01) as well as <i>Nefh</i> (<i>p </i>=<i> </i>0.02) and <i>Tubb3 </i>(<i>p </i>=<i> </i>0.009) mRNA levels were significantly decreased at 10 weeks. GABAergic synapse intensity was lower at 5 weeks, while no alterations were noted at 10 weeks. The glutamatergic synapse intensity was decreased at 5 (<i>p </i>=<i> </i>0.007) and 10 weeks (<i>p </i>=<i> </i>0.01). No changes were observed for bipolar cells, photoreceptors, and macroglia. We conclude that apoptotic processes and synapse loss precede neuronal death in this model. This slow progression rate makes the βB1-CTGF mice a suitable model to study primary open-angle glaucoma.