Hsp90α attenuates calcific aortic valve disease by upregulation HIF-1α and suppressing VIC osteogenesis

Background

Heat shock protein 90α (HSP90α), a stress-inducible isoform of the HSP90 family, has emerged as a critical modulator in cardiac remodeling and heart failure progression. While previous studies have focused on myocardial hypertrophy, infarction, and aortic calcification, recent evidence suggests that Hsp90α expression declines with the progression of calcific stimuli. However, its expression pattern and functional significance in calcific aortic valve disease (CAVD) remain poorly characterized.

Purpose

To investigate the expression pattern of Hsp90α in CAVD and to elucidate its functional role and underlying mechanism in VIC osteogenesis and calcific nodule formation.

Methods

Proteomics was employed to compare the differential expression of Hsp90α between the two sample groups (Ethics Committee Approval No. S2024-041-01). 3 cases of CAVD and 6 cases of non-CAVD were obtained from surgical resections. A mouse model of aged calcific aortic valve disease was established using ApoE-/- mice fed with high fat diet, and immunofluorescence staining was performed to compare Hsp90α expression between calcified and normal aortic valves. A calcification model of human aortic valve interstitial cells (VICs) was established to assess the effect of Hsp90α protein on osteogenic differentiation. Hsp90α adenovirus and the Hsp90α inhibitor Tanespimycin (17-AAG) were used to upregulate and downregulate Hsp90α expression in VICs, respectively. Downstream signaling mechanisms were investigated via co-immunoprecipitation, western blotting, and PCR.

Results

Proteomic profiling revealed reduced Hsp90α expression in calcified aortic valves from CAVD patients, which was confirmed by transcriptomic analysis (Figure 1, A) and tissue immunofluorescence (Figure 1, B). Consistently, Hsp90α was downregulated in aortic valves from high-fat diet aged mice with CAVD(Figure 1, D-F) and in human VICs following 14 days of osteogenic induction (Figure 1, C).

Hsp90α overexpression attenuated calcium deposition and reduced Osterix (OSX) and Runt-related transcription factor 2 (RUNX2) , whereas Hsp90α inhibition exacerbated calcification (Figure 2, A-C).

Co-immunoprecipitation identified hypoxia-inducible factor-1α (HIF-1α) as an Hsp90α-interacting partner in VICs (Figure 2, D). Hsp90α overexpression increased HIF-1α protein levels while suppressing OSX and RUNX2. Conversely, KC7F2, a pharmacological inhibition of HIF-1α can enhance calcific nodule formation and osteogenic protein expression (Figure 2, E-F).

Conclusions

This study demonstrates that Hsp90α attenuates VIC osteogenesis and calcific nodule formation in CAVD by upregulating HIF-1α protein stability and subsequently suppressing osteogenic protein. These findings position Hsp90α as a potential protective modulator in aortic valve calcification.Figure 1Figure 2