Unveiling novel LRP5 pathogenic variant in familial exudative vitreoretinopathy: Diverse phenotypic expressions in a mother-daughter duo.

PURPOSE: This report aims to delineate distinct phenotypes of Familial Exudative Vitreoretinopathy (FEVR) observed in a mother and her daughter, both harboring a novel LRP5 pathogenic variation. METHODS: The investigation involves a retrospective review of medical records accompanied by multimodal imaging. Molecular characterization was performed using whole exon sequencing, and the pathogenic variant was subsequently confirmed through Sanger sequencing. RESULT: A 6-year-old girl diagnosed with anisometropic amblyopia exhibited macular dragging and peripheral avascular retina in her right eye. Whole exon sequencing identified a previously unreported heterozygous missense LRP5 pathogenic variation, Glu528Lys. Simultaneously, her 43-year-old mother also carried the same mutation, manifesting peripheral exudations, avascular areas, and multiple microaneurysms. Notably, both cases presented distinctive phenotypes of FEVR. CONCLUSION: Our findings underscore the diversity in clinical presentations associated with FEVR, emphasizing the pivotal role of genetic evaluation. Despite variations in severity between the eyes of the same patient, it is crucial to remain vigilant for potential progression to a pathological status in the seemingly normal eye. Additionally, this study contributes to expanding the genetic spectrum of FEVR.

EFFICIENCY AND SAFETY OF INTERNAL LIMITING MEMBRANE PEELING WITH DIFFERENT FORCEPS FOR MACULAR DISEASE.

PURPOSE: To compare the efficiency and safety of internal limiting membrane (ILM) peeling between the Sharkskin forceps and End-grasping forceps in various macular diseases. METHODS: It is a prospective cohort block-randomized study conducted in a tertiary medical center. Seventy subjects with macular hole, epiretinal membrane, vitreomacular traction syndrome, or myopic foveoschisis, receiving pars plana vitrectomy and ILM peeling surgery were equally divided into Sharkskin forceps group and End-grasping forceps group. The duration of ILM peeling, the number of attempts to initiate peeling, and peeling-related retinal damage were evaluated by recorded video and optical coherence tomography. RESULTS: In the Sharkskin group, the authors demonstrated significantly fewer attempts to initiate ILM peeling compared with End-grasping group, with an average of 1.9 and 3.1 attempts ( P = 0.0001) and a lower incidence of retinal microstructural damage (20% vs. 45%, P < 0.0001). Moreover, the mean depth of inner retinal injury at the initiating site exhibited distinct difference postoperatively at 3 months between the Sharkskin group then the End-grasping group (4.3 vs. 30.0 µ m, P = 0.001). CONCLUSION: Sharkskin forceps provide better efficiency and outcome in ILM peeling in patients with various vitreomacular interface diseases, including reduced risk of retinal injury and fewer attempts to initiate ILM flap.

Stepwise activation of the pro-apoptotic protein Bid at mitochondrial membranes.

Caspase-8-cleaved Bid (cBid) associates with mitochondria and promotes the activation of BAX, leading to mitochondria outer membrane permeabilization (MOMP) and apoptosis. However, current structural models of cBid are largely based on studies using membrane vesicles and detergent micelles. Here we employ spin-label ESR and site-directed PEGylation methods to identify conformations of cBid at real mitochondrial membranes, revealing stepwise mechanisms in the activation process. Upon the binding of cBid to mitochondria, its structure is reorganized to expose the BH3 domain while leaving the structural integrity only slightly altered. The mitochondria-bound cBid is in association with Mtch2 and it remains in the primed state until interacting with BAX. The interaction subsequently triggers the fragmentation of cBid, causes large conformational changes, and promotes BAX-mediated MOMP. Our results reveal structural differences of cBid between mitochondria and other lipid-like environments and, moreover, highlight the role of the membrane binding in modifying cBid structure and assisting the inactive-to-active transition in function.

Accessing local structural disruption of Bid protein during thermal denaturation by absorption-mode ESR spectroscopy.

Bid is a requisite protein that connects death receptors to the initiation of mitochondrial-dependent apoptosis. Its structure was determined more than a decade ago, but its structure-function relationship remains largely unexplored. Here we investigate the thermostability of Bid protein and explore how the death-promoting function of Bid is affected by thermally-induced unfolding. First, we show by circular dichroism (CD) spectroscopy that Bid remains partially folded at high temperatures (350-368 K), and that the thermal unfolding of Bid is irreversible and accompanied with intermolecular associations that lead to protein aggregation. In 3 M GdnHCl, the onset of unfolding can, however, be conveniently observed at much lower temperatures around 320 K. We employ pulsed ESR dipolar spectroscopy to show that the structure of Bid remains almost unchanged between 0 and 3 M GdnHCl before thermal denaturation. More than 30 single-labeled Bid mutants are studied using the peak-height analysis method based on ESR absorption spectroscopy, in the temperature range of 300-345 K. The ESR results provide site-specific information about the temperature dependence of the local environment of Bid, thus enabling the discrimination between the onsets of unfolding and aggregation for respective sites. Consequently, we map out the local thermostability over the Bid structure and identify a new interface between helices 3, 6, and 8 as the beginning of structural unfolding. This study also investigates the apoptotic activity of the thermally-induced Bid aggregates and shows that Bid retains the death-promoting function even when unfolded and aggregated. The applicability of the new ESR absorption peak-height method is demonstrated for protein thermostability.