USP25 Regulates Platelet Function During Aging by Stabilizing Talin-1

Introduction Aging is an independent risk factor for the incidence of arterial thrombotic events. Loss of protein homeostasis is one of hallmarks for many aged-related diseases. Sing cell RNA sequencing of megakaryocyte in previous study have identified different patterns of protein ubiquitination between old and young murine. However, regulation of protein ubiquitination in platelet during aging remain poorly understood.

Fig. 1  Enhanced platelet function and decreased level of ubiquitination were observed in old mice. Expression of USP25 were confirmed in platelet. Upregulation of USP25 was found in old mice platelet. In vitro, aggregation, ATP release, spreading and clot retraction were inhibited in USP25-knockout mice, compared with age- and sex- matched wild type mice.In vivo, decreased final occlusion time of FeCl3-induced mesenteric arteriole thrombosis were observed in USP25 knock-out mice

Method Platelet functions including aggregation, ATP release were compared in old (>18 months) and young (2-3 months) mice. The level of total ubiquitination was evaluated by western blot. Available datasets were dig out to identify the most abundant deubiquitinating enzymes (DUB) and finally USP25 was chosen. Then, western blot, RT-PCR and immunofluorescence were used to confirm the expression of USP25. The platelet function was conducted in WT and USP25 knock-out mice. To characterize the mechanism of USP25 in the regulation of platelet function, ubiquitinated proteomics were conducted to identify the substrate of USP25 in platelet. Later co-immunoprecipitation and western blot were used to confirm the deubiquitinase activity of USP25 in platelet. Eventually, small molecular compound AZ-1, an USP25 inhibitor, was tested in terms of platelet function [1] [2] [3] [4] [5] [6] [7] [8] [9] [10].

Fig. 2  By using ubiquitinated proteomics, we found that talin-1 served as one target of USP25. The association of USP25 and talin-1 were confirmed by co-immunoprecipitation and western blot. We then observed that USP25 can maintain the expression of talin-1. The expression of talin-1 was significantly down-regulated when silencing USP25 in CHO-K1 cells, as well as in USP25 knock-out platelet.Further, the results showed that USP25 can directly deubiquitinate talin-1.Finally, AZ-1, an USP25 inhibitor, can decrease the platelet function

Results Enhanced platelet function and decreased level of ubiquitination were observed in old mice. The loss of ubiquitination can be caused by upregulation of DUBs. Then we screened DUBs in three datasets and determined that USP25 is one of the most abundant DUBs in both human and murine platelet. Expression of USP25 were confirmed in platelet . Upregulation of USP25 was found in old mice platelet. To determine the effect of USP25 in the regulation of platelet function, we constructed USP25-knockout mice. In vitro, aggregation, ATP release, spreading and clot retraction were inhibited in USP25-knockout mice, compared with age- and sex- matched wild type mice. In vivo, decreased final occlusion time of FeCl₃-induced mesenteric arteriole thrombosis were observed in USP25 knock-out mice. Mechanistically, by using ubiquitinated proteomics, we found that talin-1 served as one target of USP25. The association of USP25 and talin-1 were confirmed by co-immunoprecipitation and western blot. We then observed that USP25 can maintain the expression of talin-1. The expression of talin-1 was significantly down-regulated when silencing USP25 in CHO-K1 cells, as well as in USP25 knock-out platelet. Further, the results showed that USP25 can directly deubiquitinate talin-1. Finally, we found that small molecular compound AZ-1, one USP25 inhibitor, can significantly decrease platelet function including aggregation, ATP release, spreading and chamber in human platelet ([Fig. 1], [Fig. 2]).

Conclusion Overall, our study found that upregulation of USP25 may serve as a mechanism of platelet hyperactivity during aging. Furthermore, AZ1, an USP25 inhibitor, could be a potential target for thromboembolism.

Publication History

Article published online:
26 February 2024

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