Endoplasmic Reticulum Stress Disrupts Mitochondrial Bioenergetics, Dynamics and Causes Corneal Endothelial Cell Apoptosis.

Purpose: Endoplasmic reticulum (ER) and mitochondrial stress are independently associated with corneal endothelial cell (CEnC) loss in many corneal diseases, including Fuchs' endothelial corneal dystrophy (FECD). However, the role of ER stress in mitochondrial dysfunction contributing to CEnC apoptosis is unknown. The purpose of this study is to explore the crosstalk between ER and mitochondrial stress in CEnC. Methods: Human corneal endothelial cell line (HCEnC-21T) and human corneal endothelial tissues were treated with ER stressor tunicamycin. ER stress-reducing chemical 4-phenyl butyric acid (4-PBA) was used in HCEnC-21T after tunicamycin. Fuchs' corneal endothelial cell line (F35T) was used to determine differential activation of ER stress with respect to HCEnC-21T at the baseline. ER stress, mitochondrial-mediated intrinsic apoptotic, mitochondrial fission, and fusion proteins were determined using immunoblotting and immunohistochemistry. Mitochondrial bioenergetics were assessed by mitochondrial membrane potential (MMP) loss and ATP production at 48 hours after tunicamycin. Mitochondria dynamics (shape, area, perimeter) were also analyzed at 24 hours using transmission electron microscopy. Results: Treatment of HCEnC-21T cell line with tunicamycin activated three ER stress pathways (PERK-eIF2α-CHOP, IRE1α-XBP1, and ATF6), reduced cell viability, upregulated mitochondrial-mediated intrinsic apoptotic molecules (cleaved caspase 9, caspase 3, PARP, Bax, cytochrome C), downregulated anti-apoptotic Bcl-2 protein, initiated mitochondrial dysfunction by loss of MMP and lowering of ATP production, and caused mitochondrial swelling and fragmentation with increased expression of mitochondrial fission proteins (Fis1 and p-Drp1). Fuchs' CEnC (F35T) cell line also showed activation of the ER stress-related proteins (p-eIF2α, GRP78, CHOP, XBP1) compared to HCEnC-21T at the baseline. The 4-PBA ameliorated cell loss and reduced cleaved caspase 3 and 9, thereby rescuing tunicamycin-induced cell death but not mitochondrial bioenergetics in HCEnC-21T cell line. Conclusions: Tunicamycin-induced ER stress disrupts mitochondrial bioenegetics, dynamics and contributes to the loss of CEnC viability. This novel study highlights the importance of ER-mitochondria crosstalk and its contribution to CEnCs apoptosis, seen in many corneal diseases, including FECD.

Assessing the competitiveness of medical humanities research on psychiatry, otolaryngology, and ophthalmology residency program applications.

Medical humanities research is an increasing area of interest for students as medical schools become more aware of the benefits of humanities and the arts on patient care. However, medical students may feel dissuaded from pursuing medical humanities work for fear of how it will be perceived on their residency applications. In this study, residency program directors (PDs) in New York state in psychiatry, ophthalmology, and otolaryngology were surveyed about their opinions on the competitiveness of students doing medical humanities research applying to their programs. Of the 64 PDs contacted, twenty submitted responses (31.3%). When asked if a residency applicant who only had medical humanities research experience would be seriously considered for their program, 95% of PDs said yes. Furthermore, 65% of PDs said that having medical humanities research experience in addition to clinical research increased a student's chance of being accepted to their program. Thirty percent of PDs indicated that the medical humanities were an important selection criteria for their program. Qualitative responses emphasized that non-traditional projects, such as personal essays, were as valid as published journal articles when conducted with academic rigor. Many PDs also believed that the medical humanities increased compassion, empathy, and communication skills in their residents. Considering these results, medical students should feel empowered to pursue medical humanities research, even if they are applying into a competitive surgical specialty. It should not diminish their chances of being seriously considered for a program, and may even confer an advantage over their clinical research peers.