OC 64.4 - Key roles of platelet Rubicon in thrombosis and hemorrhage during ischemia-reperfusion injury

Tuesday, June 25, 2024

15:30 – 15:45 ICT

Room: Ballroom B4

Presenting Author(s)

Hu Hu, PhD

professor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)

Co-Author(s)

JL

Jingke Li

medical doctor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)
XC

Xiaoyan Chen

medical doctor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)
LL

Li Li

medical doctor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)
Fan Bu

Medical doctor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)
XD

Xin Deng

medical doctor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)
YS

Yilin Sheng

medical doctor
Department of Pathology and Pathophysiology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China and Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
hangzhou, Zhejiang, China (People's Republic)
QS

Qiming Sun

professor
Department of Biochemistry and Molecular Biology, Zhejiang University School of Medicine, Hangzhou, China
Hangzhou, Zhejiang, China (People's Republic)

Background: Platelets play major roles in causing thrombosis and mediating the pathogenesis of ischemia-reperfusion injury. Autophagy plays essential roles in platelet activation, yet the detailed mechanism of how autophagy is integrated into the platelet activation process is not clear. Rubicon is a protein well-known for its roles in regulating autophagy, vesicle transport, and inflammation; however, the role and mechanism of platelet Rubicon in thrombosis and ischemia-reperfusion injury remains undetermined.

Aims: To investigate the role of platelet Rubicon in hemostasis, thrombosis, and ischemia-reperfusion injury.

Methods: Hemostatic and thrombotic impacts of platelet Rubicon were evaluated in a megakaryocyte-platelet-specific Rubicon knockout (Rubiconf/f PF4-Cre+) mouse strain. Conventional assays of platelet function and biochemistry were employed to elucidate the interacting partners and major pathways of Rubicon in platelet. A transient middle cerebral artery occlusion (tMCAO) mouse model was used to confirm the role of platelet Rubicon in ischemic stroke and to evaluate the therapeutic potential of synthesized Rubicon peptides.

Results: Rubiconflox/floxPF4-Cre+ mice exhibited mildly prolonged mesenteric arteriolar occlusion time and slightly shortened tail-bleeding time, but a significantly expedited development of stroke and aggravated cerebral hemorrhage in the tMCAO model. Rubicon-/- platelets displayed a selectively enhanced activation response towards collagen stimulation, meanwhile showed a diminished integrin αIIbβ3 outside-in signaling. Mechanistically, the binding partner of Rubicon was switched from the VPS34 complex in resting platelets to Btk in collagen/GPVI-activated platelets, which caused the inhibition of Btk and GPVI signaling. Rubicon was also found to inhibit integrin-mediated selective autophagic degradation of Btk and thus promote αIIbβ3 outside-in signaling and maintain the stability of thrombi. Rubicon interacts with Btk through its RUN domain and cell-permeable peptides of RUN domain reduced infarction volume in tMCAO mice.

Conclusion(s): Platelet Rubicon is a potential therapeutic candidate that protects against cerebral ischemia-reperfusion injury and prevents hemorrhage.