Leucine-rich repeat kinase 2 (LRRK2) is known as the most common gene responsible for familial Parkinson disease (PD). This protein plays a key role in the neurodegenerative pathways associated with PD. LRRK2 also plays critical roles in actin dynamics and microtubule cytoskeletal assembly in the cells. In addition to PD, actin and microtubule cytoskeletons are associated with the onset and development of glaucoma by regulating the intraocular pressure (IOP) in humans and animals. However, the role of LRRK2 in regulating IOP remains unclear. Hence, this study investigated the contribution of LRRK2 to cytoskeleton-mediated regulation of IOP. LRRK2 was detected in primary human trabecular meshwork cells by immunofluorescence and western blotting analysis. Inhibition of the function and the expression of LRRK2 by LRRK2 inhibitors and LRRK2 siRNA, induced a significant reduction of TEER in these cells. TEER reduction by an LRRK2 inhibitor was attenuated by paclitaxel, a-tubulin polymerization inducer, but not by jasplakinolide, an actin polymerization inducer, suggesting that inhibition of LRRK2 induced depolymerization of microtubules, resulting in decreased TEER. Finally, LRRK2 gene knockout and LRRK2 inhibition led to a significant reduction of IOP in C57BL6J mice and Japanese white rabbits, respectively. These results suggested that LRRK2 is associated with catalysis of a-tubulin in trabecular meshwork cells and regulates IOP in mice and rabbits. Hence, there is a possibility that an LRRK2 inhibitor contributes to glaucoma therapeutics. Further evaluation to clarify the role of LRRK2 in IOP regulation is needed. SIGNIFICANCE STATEMENT: In this study, a significant contribution of LRRK2 to the regulation of intraocular pressure (IOP) was shown. Inhibition of LRRK2 results in a decrease in TEER of the trabecular meshwork cells, associated with the depolymerization of microtubules. Furthermore, both LRRK2 knockout and administration of the LRRK2 inhibitor induced a significant decrease in the IOP in animals. These results clearly indicate the role of LRRK2 in the regulation of IOP and the possibility of a novel therapeutic approach to glaucoma.

Uveal melanoma (UM) is the most common primary intra-ocular malignancy in adults and carries a high risk of metastatic disease, affecting approximately 50% of patients despite advances in local tumour control. PRAME (PReferentially expressed Antigen in MElanoma) has emerged as a marker for metastatic risk; however, evidence is largely derived from mRNA expression studies rather than routine immunohistochemistry (IHC). This study evaluates PRAME protein expression by IHC in a large UM cohort and examines its association with clinicopathological features and survival outcomes. A total of 403 UM cases were included. PRAME IHC was performed on tissue microarrays (TMAs) and/or whole tumour sections and scored as positive based on nuclear staining in >10% of tumour cells. Associations were assessed using chi-square and Mann-Whitney U tests. Survival outcomes were analysed using Kaplan-Meier curves and Cox proportional hazards models. PRAME positivity was identified in 5% of TMA cases and 40% of whole-section cases. On TMAs, PRAME expression was associated with worse overall survival (median 26 versus 50 months; p = 0.03) but not metastasis-free survival (MFS). In contrast, whole-section PRAME expression was strongly associated with shorter MFS (median 5 versus 20 months; p < 0.001) and worse overall survival (median 13 versus 52 months; p = 0.04). In multivariate analysis including age, American Joint Committee on Cancer stage and BAP1 status, whole-section PRAME positivity remained an independent adverse predictor of MFS (hazard ratio = 10.5, p = 0.002). PRAME IHC is a clinically meaningful prognostic biomarker in UM, particularly when assessed on whole tumour sections, where it provides strong independent prognostic information.