Knockdown of HSP110 attenuates hypoxia-induced pulmonary hypertension in mice through suppression of YAP/TAZ-TEAD4 pathway.

BACKGROUND: Pulmonary hypertension (PH) is a progressive and fatal cardiopulmonary disease characterized by pulmonary vascular remodeling and increased pulmonary vascular resistance and artery pressure. Vascular remodeling is associated with the excessive cell proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). In this paper, the effects of heat shock protein-110 (HSP110) on PH were investigated. METHODS: The C57BL/6 mice and human PASMCs (HPASMCs) were respectively exposed to hypoxia to establish and simulate PH model in vivo and cell experiment in vitro. To HSP110 knockdown, the hypoxia mice and HPASMCs were infected with adeno-associated virus or adenovirus carring the shRNAs (short hairpin RNAs) for HSP110 (shHSP110). For HSP110 and yes-associated protein (YAP) overexpression, HPASMCs were infected with adenovirus vector carring the cDNA of HSP110 or YAP. The effects of HSP110 on PH development in mice and cell proliferation, migration and autophagy of PASMCs under hypoxia were assessed. Moreover, the regulatory mechanisms among HSP110, YAP and TEA domain transcription factor 4 (TEAD4) were investigated. RESULTS: We demonstrated that expression of HSP110 was significantly increased in the pulmonary arteries of mice and HPASMCs under hypoxia. Moreover, knockdown of HSP110 alleviated hypoxia-induced right ventricle systolic pressure, vascular wall thickening, right ventricular hypertrophy, autophagy and proliferation of PASMCs in mice. In addition, knockdown of HSP110 inhibited the increases of proliferation, migration and autophagy of HPASMCs that induced by hypoxia in vitro. Mechanistically, HSP110 knockdown inhibited YAP and transcriptional co-activator with PDZ-binding motif (TAZ) activity and TEAD4 nuclear expression under hypoxia. However, overexpression of HSP110 exhibited the opposite results in HPASMCs. Additionally, overexpression of YAP partially restored the effects of shHSP110 on HPASMCs. The interaction of HSP110 and YAP was verified. Moreover, TEAD4 could promote the transcriptional activity of HSP110 by binding to the HSP110 promoter under hypoxia. CONCLUSIONS: Our findings suggest that HSP110 might contribute to the development of PH by regulating the proliferation, migration and autophagy of PASMCs through YAP/TAZ-TEAD4 pathway, which may help to understand deeper the pathogenic mechanism in PH development.

Molecular chaperone Hsp110 rescues a vesicle transport defect produced by an ALS-associated mutant SOD1 protein in squid axoplasm.

Mutant human Cu/Zn superoxide dismutase 1 (SOD1) is associated with motor neuron toxicity and death in an inherited form of amyotrophic lateral sclerosis (ALS; Lou Gehrig disease). One aspect of toxicity in motor neurons involves diminished fast axonal transport, observed both in transgenic mice and, more recently, in axoplasm isolated from squid giant axons. The latter effect appears to be directly mediated by misfolded SOD1, whose addition activates phosphorylation of p38 MAPK and phosphorylation of kinesin. Here, we observe that several different oligomeric states of a fusion protein, comprising ALS-associated human G85R SOD1 joined with yellow fluorescent protein (G85R SOD1YFP), which produces ALS in transgenic mice, inhibited anterograde transport when added to squid axoplasm. Inhibition was blocked both by an apoptosis signal-regulating kinase 1 (ASK1; MAPKKK) inhibitor and by a p38 inhibitor, indicating the transport defect is mediated through the MAPK cascade. In further incubations, we observed that addition of the mammalian molecular chaperone Hsc70, abundantly associated with G85R SOD1YFP in spinal cord of transgenic mice, exerted partial correction of the transport defect, associated with diminished phosphorylation of p38. Most striking, the addition of the molecular chaperone Hsp110, in a concentration substoichiometric to the mutant SOD1 protein, completely rescued both the transport defect and the phosphorylation of p38. Hsp110 has been demonstrated to act as a nucleotide exchange factor for Hsc70 and, more recently, to be able to cooperate with it to mediate protein disaggregation. We speculate that it can cooperate with endogenous squid Hsp(c)70 to mediate binding and/or disaggregation of mutant SOD1 protein, abrogating toxicity.

Immunization with heat shock protein 105-pulsed dendritic cells leads to tumor rejection in mice.

Recently, we reported that heat shock protein 105 (HSP105) DNA vaccination induced anti-tumor immunity. In this study, we set up a preclinical study to investigate the usefulness of dendritic cells (DCs) pulsed with mouse HSP105 as a whole protein for cancer immunotherapy in vivo. The recombinant HSP105 did not induce DC maturation, and the mice vaccinated with HSP105-pulsed BM-DCs were markedly prevented from the growth of subcutaneous tumors, accompanied with a massive infiltration of both CD4+ T cells and CD8+ T cells into the tumors. In depletion experiments, we proved that both CD4+ T cells and CD8+ T cells play a crucial role in anti-tumor immunity. Both CD4+ T cells and CD8+ T cells specific to HSP105 were induced by stimulation with HSP105-pulsed DCs. As a result, vaccination of mice with BM-DCs pulsed with HSP105 itself could elicit a stronger tumor rejection in comparison to DNA vaccination.