Unit:
Faculty of MedicineLibrary of the School of Health Sciences
Dissertation committee:
Δημήτριος Πικάζης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Γεώργιος Κόλλιας, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παναγιώτης Βλαχογιαννόπουλος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Αθανάσιος Τζιούφας, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Πέτρος Σφηκάκης, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Μενέλαος Μανουσάκης, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Μαριέττα Αρμακά, Ερευνήτρια Β’ Ε.ΚΕ.Β.Ε «Αλέξανδρος Φλέμιγκ»
Original Title:
Ανάλυση της έκφρασης και του ρόλου των ρυθμιστικών RNAs σε ζωικά πρότυπα Φλεγμονώδους Πολυαρθρίτιδας
Translated title:
Expression analysis and role of regulatory RNAs in animal models of Inflammatory Polyarthritis
Summary:
Regulatory RNAs, such as microRNAs (miRNAs) and lncRNAs constitute regulators of gene expression and are implicated in a variety of diseases spanning from inflammation to cancer. miRNA and lncRNA expression is deregulated in rheumatoid arthritis (RA), however, their specific role in key arthritogenic cells such as the synovial fibroblast (SF) remains elusive.
We have shown in the past that the expression of the miR-221/222 cluster is upregulated in RA SFs. Here, we demonstrate that miR-221/222 activation is downstream of major inflammatory cytokines, such as TNF and IL-1β, which promote miR-221/222 expression independently. miR-221/222 expression in SFs from the huTNFtg mouse model of arthritis correlates positively with disease progression. Targeted transgenic overexpression of miR-221/222 in SFs of the huTNFtg mouse model led to further expansion of synovial fibroblasts and disease exacerbation. miR-221/222 overexpression altered the transcriptional profile of SFs resulting in over-represented pathways in cell cycle progression and under-represented pathways in ECM regulation. Validated targets of miR-221/222 included p27 and p57 cell cycle inhibitors (previously known targets of miR-221/222), as well as Smarca1 (a chromatin remodeling component), a newly defined target of miR-221/222. In contrast, complete genetic ablation of miR-221/222 in arthritic mice led to decreased proliferation of fibroblasts, reduced synovial expansion and attenuated disease. Finally, scATAC-seq data analysis revealed increased miR-221/222 gene activity in the pathogenic and activated clusters of the intermediate and lining compartment.
Furthermore, we analyzed the expression of an underexplored class of regulatory RNAs in RA, such as the lncRNAs. To this end, analysis of differentially expressed lncRNAs in arthritic SFs from the huTNFtg mouse model was performed. Focus was given to lncRNA Gm11419, as it resides in a region next to the genetic locus of the CCL family of chemokines. Expression of Gm11419 was found to be upregulated, correlated with neighboring CCL expression and its genetic locus was conserved between the mouse and the human genome. Interestingly, several lncRNAs reside in the neighboring genetic locus of CCL genes in the human genome. These data led to the hypothesis that Gm11419 may regulate the expression of CCL genes. Gm11419 was induced under inflammatory signals, such as TNF, LPS and IL-1β and depended on TNF/TNFRI signaling. Finally, Gm11419 was detected in the chromatin fraction subcellularly, suggesting a possible function in regulating CCL expression.
Taken together, our results establish an SF-specific pathogenic role of the miR-221/222 cluster in arthritis and suggest that its therapeutic targeting in specific subpopulations should inform the design of novel fibroblast-targeted therapies for human disease. Furthermore, the study of regulatory RNAs and their role in gene expression may illuminate disease mechanisms and lead to the discovery of new therapeutic schemes.
Main subject category:
Health Sciences
Keywords:
MicroRNAs, Fibroblasts, Rheumatoid arthritis
Number of references:
344
File:
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FANI_ROUMELIOTI_PhDTHESIS.pdf
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