Restricted Presence of POU6F2 in Human Corneal Endothelial Cells Uncovered by Extension of the Promoter-level Expression Atlas

The hiPSC-derived corneal endothelial progenitor-like cell recovers the rabbit model of corneal endothelial dystrophy

INTRODUCTION

Corneal endothelial dysfunction results in cornea opacity, damaging sightedness, and affecting quality of life. A corneal transplant is the current effective intervention. Due to the scarcity of donated cornea, such an unmet medical need requires a novel therapeutic modality.

OBJECTIVES

Customizing patients' corneal endothelial progenitor cells with proliferative activity and lineage restriction properties shall offer sufficient therapeutic cells for corneal endothelial dystrophy.

METHODS

The customized induced human corneal endothelial progenitor-like cell (iHCEPLC) was obtained through cell fate conversions starting from PBMC (peripheral blood mononuclear cell), hiPSC (human induced pluripotent stem cell), and hNCC (human neural crest cell), while it finally reached the iHCEPLC state via a series of induction. Several molecular diagnoses were applied to depict its progenitor state, including RNAseq, FlowCytometer, immunostainings, and rtPCR. Significantly, it can be induced to gain differentiation maturity through contact inhibition. In addition, a BAK-mediated rabbit model of corneal endothelial dystrophy was established in the present study to test the therapeutic effectiveness of the iHCEPLC.

RESULTS

After inducing cell fate conversion, the specific HCEC markers were detected by rtPCR and immunostaining in iHCEPLC. Further, RNAseq was applied to distinguish its progenitor-like cell fate from primary human corneal endothelial cells (HECE). FlowCytometry profiled the heterogeneity subpopulation, consistently displaying a subtle difference from primary HCEC. A terminal differentiation can be induced in iHCEPLC, addressing its progenitor-like fate. iHCEPLC can restore the BAK-based rabbit model of corneal endothelial dystrophy. Immunohistochemistry verified that such acuity restoration of the BAK-treated cornea is due to the introduced iHCEPLC, and such therapeutic effectiveness is observed in the long term.

CONCLUSION

Here, we demonstrated that customized iHCEPLC has long-term therapeutic efficacy. As a progenitor cell, our iHCEPLC has a restricted cell lineage nature and can proliferate in vitro, supporting sufficient therapeutic candidate cells. Due to the immune-privileged nature of the cornea, our iHCEPLC proves the principle of therapeutical feasibility in both autogenic and allogeneic modalities.

POU6F2, a risk factor for glaucoma, myopia and dyslexia, labels specific populations of retinal ganglion cells

Pou6f2 is a genetic connection between central corneal thickness (CCT) in the mouse and a risk factor for developing primary open-angle glaucoma. POU6F2 is also a risk factor for several conditions in humans, including glaucoma, myopia, and dyslexia. Recent findings demonstrate that POU6F2-positive retinal ganglion cells (RGCs) comprise a number of RGC subtypes in the mouse, some of which also co-stain for Cdh6 and Hoxd10. These POU6F2-positive RGCs appear to be novel of ON-OFF directionally selective ganglion cells (ooDSGCs) that do not co-stain with CART or SATB2 (typical ooDSGCs markers). These POU6F2-positive cells are sensitive to damage caused by elevated intraocular pressure. In the DBA/2J mouse glaucoma model, heavily-labeled POU6F2 RGCs decrease by 73% at 8 months of age compared to only 22% loss of total RGCs (labeled with RBPMS). Additionally, Pou6f2-/- mice suffer a significant loss of acuity and spatial contrast sensitivity along with an 11.4% loss of total RGCs. In the rhesus macaque retina, POU6F2 labels the large parasol ganglion cells that form the magnocellular (M) pathway. The association of POU6F2 with the M-pathway may reveal in part its role in human glaucoma, myopia, and dyslexia.

Exposure to air pollution is associated with DNA methylation changes in sperm

Exposure to air pollutants has been associated with adverse health outcomes in adults and children who were prenatally exposed. In addition to reducing exposure to air pollutants, it is important to identify their biologic targets in order to mitigate the health consequences of exposure. One molecular change associated with prenatal exposure to air pollutants is DNA methylation (DNAm), which has been associated with changes in placenta and cord blood tissues at birth. However, little is known about how air pollution exposure impacts the sperm epigenome, which could provide important insights into the mechanism of transmission to offspring. In the present study, we explored whether exposure to particulate matter less than 2.5 microns in diameter, particulate matter less than 10 microns in diameter, nitrogen dioxide (NO2), or ozone (O3) was associated with DNAm in sperm contributed by participants in the Early Autism Risk Longitudinal Investigation prospective pregnancy cohort. Air pollution exposure measurements were calculated as the average exposure for each pollutant measured within 4 weeks prior to the date of sample collection. Using array-based genome-scale methylation analyses, we identified 80, 96, 35, and 67 differentially methylated regions (DMRs) significantly associated with particulate matter less than 2.5 microns in diameter, particulate matter less than 10 microns in diameter, NO2, and O3, respectively. While no DMRs were associated with exposure to all four pollutants, we found that genes overlapping exposure-related DMRs had a shared enrichment for gene ontology biological processes related to neurodevelopment. Together, these data provide compelling support for the hypothesis that paternal exposure to air pollution impacts DNAm in sperm, particularly in regions implicated in neurodevelopment.

Systematic review of SLC4A11, ZEB1, LOXHD1, and AGBL1 variants in the development of Fuchs' endothelial corneal dystrophy

Introduction

The pathogenic role of variants in TCF4 and COL8A2 in causing Fuchs' endothelial corneal dystrophy (FECD) is not controversial and has been confirmed by numerous studies. The causal role of other genes, SLC4A11, ZEB1, LOXHD1, and AGBL1, which have been reported to be associated with FECD, is more complicated and less obvious. We performed a systematic review of the variants in the above-mentioned genes in FECD cases, taking into account the currently available population frequency information, transcriptomic data, and the results of functional studies to assess their pathogenicity.

Methods

Search for articles published in 2005-2022 was performed manually between July 2022 and February 2023. We searched for original research articles in peer-reviewed journals, written in English. Variants in the genes of interest identified in patients with FECD were extracted for the analysis. We classified each presented variant by pathogenicity status according to the ACMG criteria implemented in the Varsome tool. Diagnosis, segregation data, presence of affected relatives, functional analysis results, and gene expression in the corneal endothelium were taken into account. Data on the expression of genes of interest in the corneal endothelium were extracted from articles in which transcriptome analysis was performed. The identification of at least one variant in a gene classified as pathogenic or significantly associated with FECD was required to confirm the causal role of the gene in FECD.

Results

The analysis included 34 articles with 102 unique ZEB1 variants, 20 articles with 64 SLC4A11 variants, six articles with 26 LOXHD1 variants, and five articles with four AGBL1 variants. Pathogenic status was confirmed for seven SLC4A11 variants found in FECD. No variants in ZEB1, LOXHD1, and AGBL1 genes were classified as pathogenic for FECD. According to the transcriptome data, AGBL1 and LOXHD1 were not expressed in the corneal endothelium. Functional evidence for the association of LOXHD1, and AGBL1 with FECD was conflicting.

Conclusion

Our analysis confirmed the causal role of SLC4A11 variants in the development of FECD. The causal role of ZEB1, LOXHD1, and AGBL1 variants in FECD has not been confirmed. Further evidence from familial cases and functional analysis is needed to confirm their causal roles in FECD.

Revisiting Existing Evidence of Corneal Endothelial Progenitors and Their Potential Therapeutic Applications in Corneal Endothelial Dysfunction

PURPOSE

A recent successful clinical trial demonstrated that a less invasive cell-injection procedure is a viable medical modality for treating corneal endothelial dystrophy. This medical advance still relies on human corneal endothelial cell (HCEC) sources derived from rare cornea donations. The progenitor of the corneal endothelium, which has the characteristics of active proliferation and lineage restriction, will be an ideal cell source for expansion ex vivo. However, the distribution of progenitor-like cells in the corneal endothelial sheet has been under debate for more than a decade.

METHODS

This paper re-examines the scientific evidence of the existence of human corneal endothelial progenitors (HCEPs) from the aspects of (1) the origin of cornea formation during ocular development, (2) manifestations from clinical studies, and (3) the distinctive properties of ex vivo-cultured subpopulations.

RESULTS

The discrepancies regarding different types of progenitor-like cells in various locations of the cornea are based on the fact that the corneal endothelium is derived from different cell types with multiple origins during corneal formation.

CONCLUSIONS

Resolving this long-standing issue in corneal biology will enable various types of progenitors to be isolated and their potencies regarding the formation of functional endothelial cells to be examined. Additionally, an effective niche system for quantitatively producing therapeutic cells can be formulated to satisfy the burning need associated with corneal endothelial dystrophy in the future.

TFAP2B overexpression contributes to tumor growth and progression of thyroid cancer through the COX-2 signaling pathway

Thyroid cancer is commonly seen in the clinic with a rapidly increasing incidence globally. COX-2 overexpression correlates with the pathologic type of thyroid carcinoma, and it has been suggested that COX-2 overexpression is associated with a poor prognosis. However, little is known about its upstream regulatory mechanism. Bioinformatics suggested that transcription factor AP-2 beta (TFAP2B) might specifically bind to the COX-2 promoter, which was confirmed by biotin-labeled COX-2 promoter pulldown and luciferase reporter assays. We performed western blot and immunohistochemical staining to detect the expression of TFAP2B/COX-2 in thyroid cancer tissues (T) and the matched adjacent noncarcinoma tissues (ANT), and investigated the relationship between TFAP2B/COX-2 expression and clinical pathological factors in thyroid cancer patients. Afterward, MTS, colony formation, cell-apoptosis assay, transwell-invasion and scratch assays were performed to examine the proliferation, apoptosis, invasion, and migration of thyroid cancer cells with TFAP2B knocked down or overexpressed. The mouse xenograft experiment was performed to study in vivo the proliferation of thyroid cancer cells with TFAP2B knocked down or overexpressed. We found that TFAP2B bound to the promoter of COX-2 to activate its expression. Western blot and immunohistochemistry showed that TFAP2B/COX-2 was highly expressed in thyroid cancer, and high TFAP2B and COX-2 expression was associated with aggressive clinicopathological features in thyroid cancer. TFAP2B mediated thyroid cancer cell proliferation, apoptosis, invasion, and migration via the COX-2 signaling pathway in vitro and in vivo. TFAP2B bound to the promoter of COX-2 to activate its expression, indicating that TFAP2B is a critical regulatory molecule in the COX-2 signaling pathway that promoted tumor progression in thyroid cancer.

Transcription factor TFAP2B up-regulates human corneal endothelial cell-specific genes during corneal development and maintenance

The corneal endothelium, which originates from the neural crest via the periocular mesenchyme (PM), is crucial for maintaining corneal transparency. The development of corneal endothelial cells (CECs) from the neural crest is accompanied by the expression of several transcription factors, but the contribution of some of these transcriptional regulators to CEC development is incompletely understood. Here, we focused on activating enhancer-binding protein 2 (TFAP2, AP-2), a neural crest-expressed transcription factor. Using semiquantitative/quantitative RT-PCR and reporter gene and biochemical assays, we found that, within the AP-2 family, the TFAP2B gene is the only one expressed in human CECs in vivo and that its expression is strongly localized to the peripheral region of the corneal endothelium. Furthermore, the TFAP2B protein was expressed both in vivo and in cultured CECs. During mouse development, TFAP2B expression began in the PM at embryonic day 11.5 and then in CECs during adulthood. siRNA-mediated knockdown of TFAP2B in CECs decreased the expression of the corneal endothelium-specific proteins type VIII collagen α2 (COL8A2) and zona pellucida glycoprotein 4 (ZP4) and suppressed cell proliferation. Of note, we also found that TFAP2B binds to the promoter of the COL8A2 and ZP4 genes. Furthermore, CECs that highly expressed ZP4 also highly expressed both TFAP2B and COL8A2 and showed high cell proliferation. These findings suggest that TFAP2B transcriptionally regulates CEC-specific genes and therefore may be an important transcriptional regulator of corneal endothelial development and homeostasis.