TIPARP is involved in the regulation of intraocular pressure

Stop codon variant in EFEMP1 is associated with primary open-angle glaucoma due to impaired regulation of aqueous humor outflow

It is known that the actin cytoskeleton and its associated cellular interactions in the trabecular meshwork (TM) and juxtacanalicular tissues mainly contribute to the formation of resistance to aqueous outflow of the eye. Fibulin-3, encoded by EFEMP1 gene, has a role in extracellular matrix (ECM) modulation, and interacts with enzymatic ECM regulators, but the effects of fibulin-3 on TM cells has not been explored. Here, we report a stop codon variant (c.T1480C, p.X494Q) of EFEMP1 that co-segregates with primary open angle glaucoma (POAG) in a Chinese pedigree. In the human TM cells, overexpression of wild-type fibulin-3 reduced intracellular actin stress fibers formation and the extracellular fibronectin levels by inhibiting Rho/ROCK signaling. TGFβ1 up-regulated fibulin-3 protein levels in human TM cells by activating Rho/ROCK signaling. In rat eyes, overexpression of wild-type fibulin-3 decreased the intraocular pressure and the fibronectin expression of TM, however, overexpression of mutant fibulin-3 (c.T1480C, p.X494Q) showed opposite effects in cells and rat eyes. Taken together, the EFEMP1 variant may impair the regulatory capacity of fibulin-3 which has a role for modulating the cell contractile activity and ECM synthesis in TM cells, and in turn may maintain normal resistance of aqueous humor outflow. This study contributes to the understanding of the important role of fibulin-3 in TM pathophysiology and provides a new possible POAG therapeutic approach.

Elevated retinal fibrosis in experimental myopia is involved in the activation of the PI3K/AKT/ERK signaling pathway

OBJECTIVE

This study aimed to investigate the regulatory role of the PI3K/AKT/ERK signaling pathway in retinal fibrosis in -6.0 diopter (D) lens-induced myopic (LIM) guinea pigs.

METHODS

Biological measurements of eye tissues were performed on guinea pigs to obtain their refraction, axial length, retinal thickness, physiological function, and fundus retinal status. In addition, Masson staining and immunohistochemical (IHC) assay were further done to explore the changes in retinal morphology after myopic induction. Meanwhile, hydroxyproline (HYP) content was measured to evaluate the degree of retinal fibrosis. Moreover, the levels of the PI3K/AKT/ERK signaling pathway and fibrosis-related molecules in retinal tissues including matrix metalloproteinase 2(MMP2), collagen type I (Collagen I), and α-smooth muscle actin (α-SMA) were detected by real-time quantitative PCR (qPCR) and Western blot.

RESULTS

The LIM guinea pigs showed a significant myopic shift in refractive error and an increase in axial length compared with those of the normal control (NC) group. Masson staining, hydroxyproline content determination, and IHC showed an increase in retinal fibrosis. After myopic induction, qPCR and western blot analyses showed that phosphatidylinositol-3-kinase catalytic subunit α (PIK3CA), protein kinase B (AKT), extracellular regulated protein kinase 1/2 (ERK1/2), MMP2, Collagen I, and α-SMA were consistently elevated in the LIM group than those in the NC group.

CONCLUSION

The PI3K/AKT/ERK signaling pathway was activated in the retinal tissues of myopic guinea pigs, which exaggerated fibrotic lesions and reduced retinal thickness, ultimately leading to retinal physiological dysfunctions in myopic guinea pigs.

A Multi-omic Analysis of the Human Lung Reveals Distinct Cell Specific Aging and Senescence Molecular Programs

Age is a major risk factor for lung disease. To understand the mechanisms underlying this association, we characterized the changing cellular, genomic, transcriptional, and epigenetic landscape of lung aging using bulk and single-cell RNAseq (scRNAseq) data. Our analysis revealed age-associated gene networks that reflected hallmarks of aging, including mitochondrial dysfunction, inflammation, and cellular senescence. Cell type deconvolution revealed age-associated changes in the cellular composition of the lung: decreased alveolar epithelial cells and increased fibroblasts and endothelial cells. In the alveolar microenvironment, aging is characterized by decreased AT2B cells and reduced surfactant production, a finding that was validated by scRNAseq and IHC. We showed that a previously reported senescence signature, SenMayo, captures cells expressing canonical senescence markers. SenMayo signature also identified cell-type specific senescence-associated co-expression modules that have distinct molecular functions, including ECM regulation, cell signaling, and damage response pathways. Analysis of somatic mutations showed that burden was highest in lymphocytes and endothelial cells and was associated with high expression of senescence signature. Finally, aging and senescence gene expression modules were associated with differentially methylated regions, with inflammatory markers such as IL1B, IL6R, and TNF being significantly regulated with age. Our findings provide new insights into the mechanisms underlying lung aging and may have implications for the development of interventions to prevent or treat age-related lung diseases.