High expression of ubiquitin-specific peptidase 39 is associated with the development of vascular remodeling

USP39 promotes retinal pathological angiogenesis in retinopathy of prematurity by stabilizing SIRT2 expression through deubiquitination

BACKGROUND

Retinopathy of prematurity (ROP) is a major cause of childhood blindness worldwide, highlighted by retinal neovascularization. Ubiquitin is present throughout the retina. The deubiquitinating enzyme ubiquitin-specific protease 39 (USP39) has been reported to be involved in angiogenesis. Here, this study aimed to investigate the effects of USP39 on ROP and its associated mechanism.

METHODS

Hypoxia-induced human retinal microvascular endothelial cells (hRMECs) were adopted for functional analyses. Detection of mRNA and protein was conducted using quantitative real-time PCR and western blotting. Cell migration, invasion and angiogenesis were evaluated using transwell and tube formation assays. Protein interaction was determined by immunoprecipitation assay. Oxygen-induced retinopathy (OIR) mouse models were used for in vivo analysis.

RESULTS

USP39 level was higher in hypoxia-induced hRMECs, functionally, USP39 silencing reversed hypoxia-induced migration, invasion and angiogenesis in hRMECs. In further mechanism analysis, we found that USP39 stabilized SIRT2 protein expression in hRMECs by inducing SIRT2 deubiquitination. Moreover, SIRT2 up-regulation abated hypoxia-evoked migration, invasion and angiogenesis in hRMECs. Besides that, the inhibitory effects of USP39 silencing on hypoxia-induced metastatic and angiogenic behaviors were abolished after SIRT2 overexpression. In addition, USP39 silencing blocked the activation of phosphoinositide 3-kinase (PI3K)/protein kinase B pathway (AKT) by regulating SIRT2. In vivo assay showed that levels of USP39, SIRT2, matrix metalloproteinase (MMP)-2 (MMP-2), MMP-9 and Vascular endothelial growth factor A (VEGFA) were increased in the retinas of OIR mice, while intravitreal injection of USP39 short hairpin RNA (shRNA) could reduce their expression.

CONCLUSION

USP39 stabilized SIRT2 expression by deubiquitination and promoted hypoxia-induced metastatic and angiogenic behaviors of RMECs in vitro, as well as retinal angiogenesis in vivo.

Endothelial deubiquinatase YOD1 mediates Ang II-induced vascular endothelial-mesenchymal transition and remodeling by regulating β-catenin

Hypertension is a prominent contributor to vascular injury. Deubiquinatase has been implicated in the regulation of hypertension-induced vascular injury. In the present study we investigated the specific role of deubiquinatase YOD1 in hypertension-induced vascular injury. Vascular endothelial endothelial-mesenchymal transition (EndMT) was induced in male WT and YOD1-/- mice by administration of Ang II (1 μg/kg per minute) via osmotic pump for four weeks. We showed a significantly increased expression of YOD1 in mouse vascular endothelial cells upon Ang II stimulation. Knockout of YOD1 resulted in a notable reduction in EndMT in vascular endothelial cells of Ang II-treated mouse; a similar result was observed in Ang II-treated human umbilical vein endothelial cells (HUVECs). We then conducted LC-MS/MS and co-immunoprecipitation (Co-IP) analyses to verify the binding between YOD1 and EndMT-related proteins, and found that YOD1 directly bound to β-catenin in HUVECs via its ovarian tumor-associated protease (OTU) domain, and histidine at 262 performing deubiquitination to maintain β-catenin protein stability by removing the K48 ubiquitin chain from β-catenin and preventing its proteasome degradation, thereby promoting EndMT of vascular endothelial cells. Oral administration of β-catenin inhibitor MSAB (20 mg/kg, every other day for four weeks) eliminated the protective effect of YOD1 deletion on vascular endothelial injury. In conclusion, we demonstrate a new YOD1-β-catenin axis in regulating Ang II-induced vascular endothelial injury and reveal YOD1 as a deubiquitinating enzyme for β-catenin, suggesting that targeting YOD1 holds promise as a potential therapeutic strategy for treating β-catenin-mediated vascular diseases.

Murine double minute 2-mediated estrogen receptor 1 degradation activates macrophage migration inhibitory factor to promote vascular smooth muscle cell dedifferentiation and oxidative stress during thoracic aortic aneurysm progression

Estrogen receptor 1 (ESR1) has been recently demonstrated as a potential diagnostic biomarker for thoracic aortic aneurysm (TAA). However, its precise role in the progression of TAA remains unclear. In this study, TAA models were established in ApoE-knockout mice and primary mouse vascular smooth muscle cells (VSMCs) through treatment with angiotensin (Ang) II. Our findings revealed a downregulation of ESR1 in Ang II-induced TAA mice and VSMCs. Upregulation of ESR1 mitigated expansion and cell apoptosis in the mouse aorta, reduced pathogenetic transformation of VSMCs, and reduced inflammatory infiltration and oxidative stress both in vitro and in vivo. Furthermore, we identified macrophage migration inhibitory factor (MIF) as a biological target of ESR1. ESR1 bound to the MIF promoter to suppress its transcription. Artificial MIF restoration negated the mitigating effects of ESR1 on TAA. Additionally, we discovered that murine double minute 2 (MDM2) was highly expressed in TAA models and mediated protein degradation of ESR1 through ubiquitination modification. Silencing of MDM2 reduced VSMC dedifferentiation and suppressed oxidative stress. However, these effects were reversed upon further silencing of ESR1. In conclusion, this study demonstrates that MDM2 activates MIF by mediating ESR1 degradation, thus promoting VSMC dedifferentiation and oxidative stress during TAA progression.

USP39 regulates the cell cycle, survival, and growth of human leukemia cells

Ubiquitin-specific peptidase 39 (USP39) is one member of the cysteine proteases of the USP family, which represents the largest group of DeUbiquitinases with more than 50 members in humans. The roles of USP39 in human cancer have been widely investigated. However, the roles of USP39 in human leukemia and the underlying mechanism remain unknown. Here we reported the function of USP39 in human leukemia. We observed that the expression of USP39 was up-regulated in human leukemia cells and the high expression of USP39 was correlated with poor survival of the patients with leukemia. Lentivirus-mediated knockdown of USP39 repressed the proliferation and colony formation of human leukemia cell lines HL-60 and Jurkat cells. Mechanism study showed that USP39 knockdown induced the arrest of cell cycle and apoptosis of leukemia cells. In addition, our microarray and bioinformatic analysis demonstrated that USP39 regulated diverse cellular signaling pathways that were involved in tumor biology, and several pivotal genes (IRF1, Caspase 8, and SP1) have been validated by quantitative real-time polymerase chain reaction. Knockdown or IRF1 partially restored the proliferation rate of leukemia cells with USP39 knockdown. Taken together, our findings implicate that USP39 promotes the development of human leukemia by regulating cell cycle, survival, and proliferation of the cells.