Biology subjects

Perkumas, K.

Publications and source records attributed to Perkumas, K..

3 recordsLinked to original sources

bioRxiv2026

Molecular profiling implicates immune-driven adaptive homeostasis in maintaining intraocular pressure with age

Aging and ocular hypertension are primary risk factors for glaucoma - a major cause of blindness worldwide. Ocular hypertension results from dysfunction in the outflow tissues - the trabecular meshwork (TM) and Schlemm's canal (SC), which are key regulators of intraocular pressure (IOP) homeostasis. Despite lifelong multifaceted stress to the outflow pathway, ocular hypertension sufficient to develop glaucoma occurs in only a minority of individuals. The mechanisms that preserve physiological IOP with aging in most individuals remain poorly understood. Using single-cell RNA sequencing and protein validation in mouse outflow tissues, we found that aging is accompanied by subtype-specific changes in TM cells, including altered extracellular matrix maintenance, reduced trophic signaling to SC, and increased profibrotic signaling. Coincident with these changes, we observed age-dependent immune remodeling, marked by increased macrophage abundance in outflow tissues. Our model predicts that macrophages maintain SC homeostasis via VEGFA signaling - normally supplied by the TM and required for normal SC function, but impaired with age. This pattern supports a paradigm in which adaptive immune remodeling contributes to preserving IOP homeostasis despite progressive aging-associated cellular dysfunction. More broadly, we identify the TM/SC outflow pathway as a model for understanding how aging tissues preserve physiological function through coordinated structural, trophic, and adaptive immune remodeling.

cell biology↗

bioRxiv2026

Time-dependent Glucocorticoid-Induced Transcriptomic Changes in Human Trabecular Meshwork and Schlemm's Canal

PurposeTo identify the transcriptomic changes induced by dexamethasone (DEX) in trabecular meshwork (TM) and Schlemms canal endothelial (SCE) cells with RNA-sequencing (RNA-seq). MethodsHuman TM (n=10) and SCE cell strains (n=5) were isolated from healthy donor eyes and exposed to DEX 100nM and vehicle (control). Three DEX exposure times were evaluated: 1-hour, 6-hours, and 2 days. RNA-seq was performed on Illuminas TruSeq platform and gene expression was quantified using featureCount. DESeq2 paired (treated and untreated) sample test was applied to identify genes transcriptionally responsive to DEX (DEGs) at false discovery rate <0.05. Gene-set enrichment analyses were performed on DEGs. DEGs were tested for association with glaucoma (POAG) and intraocular pressure (IOP). ResultsNine TM and 4 SCE strains passed quality control. After 2-day DEX exposure, there were 857 and 2,086 DEGs in TM and SCE, respectively. Of these, 411 genes were differentially expressed in both TM and SCE, including FKBP5 (17.3-fold-change, p=6.9x10-53) and FAM107A (25.1-fold-change, p=4.0x10-240), the most significant DEG after 2-day DEX exposure in TM and SCE, respectively. The 2-day DEX DEGs in TM and SCE were enriched in cell adhesion, extracellular matrix, and response to stimulus in Gene Ontologies (p<3.7x10-6). Early response DEGs were enriched in immune-related processes. Thirteen DEGs in TM were significant at all three time points, including PER1. LTBP2 is a TM-only DEG and FAM105A a SCE-only DEG associated with IOP and POAG risk. ConclusionsThis study identified candidate genes and pathways for glucocorticoid-induced ocular hypertension which can be further explored in human genetic analyses.

genomics↗

bioRxiv2018

Probe Sensitivity to Cortical versus Intracellular Cytoskeletal Network Stiffness

In development, wound healing, and pathology, cell biomechanical properties are increasingly recognized as being of central importance. To measure these properties, experimental probes of various types have been developed, but how each probe reflects the properties of heterogeneous cell regions has remained obscure. To better understand differences attributable to the probe technology, as well as to define the relative sensitivity of each probe to different cellular structures, here we took a comprehensive approach. We studied two cell types --Schlemms canal (SC) endothelial cells and mouse embryonic fibroblasts (MEFs) - using four different probe technologies: 1) atomic force microscopy (AFM) with sharp-tip; 2) AFM with round-tip; 3) optical magnetic twisting cytometry (OMTC); and 4) traction microscopy (TM). Perturbation of SC cells with dexamethasone treatment, a-actinin overexpression, or Rho-A overexpression caused increases in traction reported by TM and stiffness reported by sharp-tip AFM, as compared to corresponding controls. By contrast, under these same experimental conditions, stiffness reported by round-tip AFM and by OMTC indicated little change. Knock out (KO) of vimentin in MEFs caused a diminution of traction reported by TM, as well as stiffness reported by sharp-tip and round-tip AFM. However, stiffness reported by OMTC in vimentin KO MEFs was greater than in wild-type. Finite element analysis demonstrated that this paradoxical OMTC result in vimentin KO MEFs could be attributed to reduced cell thickness. Our results also suggest that vimentin contributes not only to intracellular network stiffness but also cortex stiffness. Taken together, this evidence suggests that AFM sharp-tip and TM emphasize properties of the actin-rich shell of the cell whereas round-tip AFM and OMTC emphasize those of the non-cortical intracellular network.

biophysics↗