FOXO1 and Its Role in Barrier Function in the Junctional Epithelium after Bacterial Infections.

Lucy Kim

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Kim, Lucy
Faculty / Advisor: Graves, Dana T.
University of Pennsylvania School of Dental Medicine, Department of Periodontics

Introduction

The aim of this project was to investigate the role of forkhead box O1 (FOXO1) in keratinocytes within the junctional epithelium through bioinformatic analyses. In particular, this study specifically focused on FOXO1’s effect on the genes involved in barrier function within the keratinocytes.

Methods

A transcriptome of 20,000 genes that were obtained from normal human epidermal keratinocytes that were incubated in either standard or high glucose media followed by transfection with FOXO1 or scrambled siRNA were used. Both Database for Annotation Visualization and Integrated Discovery (DAVID) and Gene Set Enrichment Analysis (GSEA) were utilized to analyze the obtained data. Four phenotypes were created to categorize the genes: low glucose (LG) scramble FOXO1 (scrFOXO1), LG siFOXO1, high glucose (HG) scramble FOXO1, and HG siFOXO1. From the listed phenotypes, HG scrFOXO1 vs LG scrFOXO1 and LG siFOXO1 vs LG scrFOXO1 were analyzed. Based on our hypothesis, we predicted the low glucose scrFOXO1 condition would show FOXO1’s protective role through the upregulation of key markers involved in maintaining epithelial integrity within the keratinocytes.

Results

In the HG scrFOXO1 vs LG scrFOXO1 analysis, pathways related to inflammatory responses, interleukin productions, and cytokine and chemokine activities were upregulated in the HG scrFOXO1 group. This result confirmed FOXO1’s role in promoting inflammation in hyperglycemic conditions. In the LG scrFOXO1 group, categories involving RNA activities, RNA and histone methylations, and ribosome biogenesis were upregulated. Further research needs to be conducted to explain this finding. In the LG siFOXO1 vs LG scrFOXO1 analysis, multiple categories involving antigen processing and presentation of peptide antigens were upregulated in the LG siFOXO1 group. This novel finding is another area that requires further investigation. In the LG scrFOXO1 group, a heterogeneous mixture of pathways associated with cell-to-cell adhesion, wound healing and barrier function was identified. This finding confirmed our hypothesis of FOXO1 promoting epithelial barrier function and the previous finding of FOXO1’s positive impact on wound healing.

Conclusion

Through the utilization of bioinformatics tools such as DAVID and GSEA, this study has allowed us to enhance the understanding of FOXO1’s protective role on the barrier function of keratinocytes within the junctional epithelium. However, further analyses need to be conducted to confirm the roles of the additional pathways that were identified. Lastly, the analyses on the remaining phenotypes will need to be completed to fully advance our knowledge of FOXO1 and its effects on maintaining epithelial integrity.