Scleraxis expressing scleral cells respond to inflammatory stimulation

FOXM1 Participates in Scleral Remodeling in Myopia by Upregulating APOA1 Expression Through METTL3/YTHDF2

Purpose

Apolipoprotein A1 (APOA1) is a potential crucial protein and treatment goal for pathological myopia in humans. This study set out to discover the function of APOA1 in scleral remodeling in myopia and its underlying mechanisms.

Methods

A myopic cell model was induced using hypoxia. Following loss- and gain-of function experiments, the expression of the myofibroblast transdifferentiation-related and collagen production-related factors Forkhead box M1 (FOXM1), APOA1, and methyltransferase-like 3 (METTL3) in the myopic cell model was examined by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting. The proliferation and apoptosis were determined by Cell Counting Kit-8 assay and flow cytometry, respectively. Chromatin immunoprecipitation (ChIP) was employed to examine FOXM1 enrichment in the METTL3 promoter, methylated RNA immunoprecipitation (Me-RIP) to examine the N6-methyladenosine (m6A) modification level of APOA1, and photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) to examine the binding between METTL3 and APOA1.

Results

Hypoxia-induced human scleral fibroblasts (HSFs) had high APOA1 and FOXM1 expression and low METTL3 expression. FOXM1 knockdown elevated METTL3 expression and downregulated APOA1 expression. FOXM1 was enriched in METTL3 promoter. APOA1 or FOXM1 knockdown or METTL3 overexpression reversed the hypoxia-induced elevation in vinculin, paxillin, and α-smooth muscle actin (α-SMA) levels and apoptosis and the reduction in collagen, type I, alpha 1 (COL1A1) level and cell proliferation in HSFs. METTL3 or YTH N6-methyladenosine RNA binding protein F2 (YTHDF2) knockdown or APOA1 overexpression reversed the impacts of FOXM1 knockdown on vinculin, paxillin, α-SMA, and COL1A1 expression and cell proliferation and apoptosis.

Conclusions

FOXM1 elevated the m6A methylation level of APOA1 by repressing METTL3 transcription and enhanced APOA1 mRNA stability and transcription by reducing the YTHDF2-recognized m6A methylated transcripts.

The Chemistry and Biology of Collagen Hybridization

Collagen provides mechanical and biological support for virtually all human tissues in the extracellular matrix (ECM). Its defining molecular structure, the triple-helix, could be damaged and denatured in disease and injuries. To probe collagen damage, the concept of collagen hybridization has been proposed, revised, and validated through a series of investigations reported as early as 1973: a collagen-mimicking peptide strand may form a hybrid triple-helix with the denatured chains of natural collagen but not the intact triple-helical collagen proteins, enabling assessment of proteolytic degradation or mechanical disruption to collagen within a tissue-of-interest. Here we describe the concept and development of collagen hybridization, summarize the decades of chemical investigations on rules underlying the collagen triple-helix folding, and discuss the growing biomedical evidence on collagen denaturation as a previously overlooked ECM signature for an array of conditions involving pathological tissue remodeling and mechanical injuries. Finally, we propose a series of emerging questions regarding the chemical and biological nature of collagen denaturation and highlight the diagnostic and therapeutic opportunities from its targeting.

Identifying TNF and IL6 as potential hub genes and targeted drugs associated with scleritis: A bio-informative report

Background

Scleritis is a serious inflammatory eye disease that can lead to blindness. The etiology and pathogenesis of scleritis remain unclear, and increasing evidence indicates that some specific genes and proteins are involved. This study aimed to identify pivotal genes and drug targets for scleritis, thus providing new directions for the treatment of this disease.

Methods

We screened candidate genes and proteins associated with scleritis by text-mining the PubMed database using Python, and assessed their functions by using the DAVID database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to identify the functional enrichment of these genes and proteins. Then, the hub genes were identified with CytoHubba and assessed by protein-protein interaction (PPI) network analysis. And the serum from patients with active scleritis and healthy subjects were used for the validation of hub genes. Finally, the DGIdb database was used to predict targeted drugs for the hub genes for treating scleritis.

Results

A total of 56 genes and proteins were found to be linked to scleritis, and 65 significantly altered pathways were identified in the KEGG analysis (FDR < 0.05). Most of the top five pathways involved the categories “Rheumatoid arthritis,” “Inflammatory bowel disease”, “Type I diabetes mellitus,” and “Graft-versus-host disease”. TNF and IL6 were considered to be the top 2 hub genes through CytoHubba. Based on our serum samples, hub genes are expressed at high levels in active scleritis. Five scleritis-targeting drugs were found among 88 identified drugs.

Conclusions

This study provides key genes and drug targets related to scleritis through bioinformatics analysis. TNF and IL6 are considered key mediators and possible drug targets of scleritis. Five drug candidates may play an important role in the diagnosis and treatment of scleritis in the future, which is worthy of the further experimental and clinical study.

Is the human sclera a tendon-like tissue? A structural and functional comparison

Collagen rich connective tissues fulfill a variety of important functions throughout the human body, most of which having to resist mechanical challenges. This review aims to compare structural and functional aspects of tendons and sclera, two tissues with distinct location and function, but with striking similarities regarding their cellular content, their extracellular matrix and their low degree of vascularization. The description of these similarities meant to provide potential novel insight for both the fields of orthopedic research and ophthalmology.