Deciphering the long noncoding RNA, MALAT1 and TUG1-Directed Epigenetic Network in Aortic Stenosis

J. I. Muñoz-Manco (Bonn)¹, A. M. Utami (Bonn)², Z. Li (Bonn)³, Y. Sheng (Bonn)⁴, H. Li (Bonn)⁵, P. R. Goody (Bonn)⁶, K. Wilhelm-Jüngling (Bonn)⁷, N. Gerdes (Düsseldorf)⁸, S. Zimmer (Bonn)⁶, F. Bakhtiary (Bonn)⁹, G. Nickenig (Bonn)⁶, M. R. Hosen (Bonn)^1
1Heart Center, Molecular Cardilogy Internal Medicine-II Bonn, Deutschland; ²Heart Center Bonn, Molecular Cardiology, Department of Internal Medicine II, University Hospital Bonn, Department of Internal Medicine II, University Hospital Bonn Bonn, Deutschland; ³Heart Center Bonn, Molecular Cardiology, Department of Internal Medicine II Department of Internal Medicine II, University Hospital Bonn Bonn, Deutschland; ⁴Heart Center, Molecular Cardiology Med-II Bonn, Deutschland; ⁵Heart Center Bonn, Molecular Cardiology, Department of Internal Medicine II, University Hospital Bonn, Venusberg-Campus 1, Department of Internal Medicine II, University Hospital Bonn Bonn, Deutschland; ⁶Universitätsklinikum Bonn Medizinische Klinik und Poliklinik II Bonn, Deutschland; ⁷Institute for Cardiovascular Sciences Endothelial Signaling and Metabolism Bonn, Deutschland; ⁸Universitätsklinikum Düsseldorf Klinik für Kardiologie, Pneumologie und Angiologie Düsseldorf, Deutschland; ⁹Universitätsklinikum Bonn Klinik und Poliklinik für Herzchirurgie Bonn, Deutschland

Background: Calcific Aortic Valve Stenosis (CAVS) represents a significant and growing clinical burden in aging populations, characterized by an active pathological process of endothelial dysfunction, chronic inflammation, and progressive calcification. Despite its prevalence, no medical therapies exist to halt or reverse disease progression. Long non-coding RNAs (lncRNAs) have emerged as critical epigenetic regulators in cardiovascular disease, yet their specific roles and therapeutic potential in CAVS remain largely unexplored. This study aims to define the causal contributions and mechanistic pathways of two prominent lncRNAs, MALAT1 and TUG1, in driving the inflammatory and calcific processes central to CAVS pathology.

Methods and Results: To elucidate the functional roles of MALAT1 and TUG1, we employed loss-of-function approaches in primary human valvular endothelial cells (VECs) and valvular interstitial cells (VICs). Efficient siRNA-mediated knockdown of both lncRNAs was confirmed via qRT-PCR (One-way ANOVA, p<0.05). Initial functional characterization using wound-healing and tube formation assays indicated that MALAT1 and TUG1 silencing did not significantly alter cell migration or angiogenic capacity under baseline conditions. However, under conditions of oxidative stress induced by H₂O₂ (100 µM), a key driver of valvular pathogenesis, a critical phenotype emerged. Knockdown of MALAT1 and TUG1 resulted in a significant increase in cell viability (MTT assay, p<0.05) and a concurrent significant reduction in LDH release (p<0.05) in VECs, suggesting these lncRNAs are involved in modulating cell survival pathways under pathological stress. Furthermore, transcriptional analysis revealed that silencing MALAT1 and TUG1 led to a marked downregulation of a panel of pro-inflammatory genes, including IL-1β, IL-6, NLRP3, ICAM-1, and CASP-1. This was associated with a suppression of NF-κB pathway activity, indicating that these lncRNAs function as upstream amplifiers of a key immunogenic and inflammatory cascade in valve cells.

Conclusion and Future Perspectives: Our data establish MALAT1 and TUG1 as pivotal regulators of stress-induced cell survival and NF-κB-driven inflammation in the aortic valve microenvironment, positioning them as contributors to the early pathological remodeling in CAVS. The finding that they modulate cell viability under oxidative duress, rather than migration, points to a specific role in resisting apoptosis and promoting a pro-inflammatory cell state. Future studies will focus on delineating the precise molecular mechanisms, with a particular emphasis on their interactions with candidate microRNAs (miR-133b, miR-145) and the validation of these pathways in more complex, physiologically relevant systems. We will utilize patient-derived VEC-VIC co-culture models to investigate paracrine crosstalk and proceed to in vivo validation in a murine model of CAVS. The ultimate goal is to assess the therapeutic potential of targeting these lncRNAs to mitigate the inflammatory and calcific processes that define this devastating disease.