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Updated: Jul 6, 2025
LC-MS Analysis of Human Platelets as a Platform for Studying Mitochondrial Metabolism
Published on: April 4, 2016
Mitofusin-2 Regulates Platelet Mitochondria and Function
Shancy Jacob1, Yasuhiro Kosaka1, Seema Bhatlekar1
1Molecular Medicine Program, (S.J., Y.K., S. Bhatlekar, F.D., H.B., A.M., V.M., E.T., G.H., N.K., B.K.M., B.J.S., K.H., N.D.T., S. Boudina, R.A.C., M.T.R., P.F.B., A.S.W., J.W.R.), University of Utah, Salt Lake City, UT.
Background:
Single-nucleotide polymorphisms linked with the rs1474868 T allele (MFN2 [mitofusin-2] T/T) in the human mitochondrial fusion protein MFN2 gene are associated with reduced platelet MFN2 RNA expression and platelet counts. This study investigates the impact of MFN2 on megakaryocyte and platelet biology.
Methods:
Mice with megakaryocyte/platelet deletion of Mfn2 (Mfn2-/- [Mfn2 conditional knockout]) were generated using Pf4-Cre crossed with floxed Mfn2 mice. Human megakaryocytes were generated from cord blood and platelets isolated from healthy subjects genotyped for rs1474868. Ex vivo approaches assessed mitochondrial morphology, function, and platelet activation responses. In vivo measurements included endogenous/transfused platelet life span, tail bleed time, transient middle cerebral artery occlusion, and pulmonary vascular permeability/hemorrhage following lipopolysaccharide-induced acute lung injury.
Results:
Mitochondria was more fragmented in megakaryocytes derived from Mfn2-/- mice and from human cord blood with MFN2 T/T genotype compared with control megakaryocytes. Human resting platelets of MFN2 T/T genotype had reduced MFN2 protein, diminished mitochondrial membrane potential, and an increased rate of phosphatidylserine exposure during ex vivo culture. Platelet counts and platelet life span were reduced in Mfn2-/- mice accompanied by an increased rate of phosphatidylserine exposure in resting platelets, especially aged platelets, during ex vivo culture. Mfn2-/- also decreased platelet mitochondrial membrane potential (basal) and activated mitochondrial oxygen consumption rate, reactive oxygen species generation, calcium flux, platelet-neutrophil aggregate formation, and phosphatidylserine exposure following dual agonist activation. Ultimately, Mfn2-/- mice showed prolonged tail bleed times, decreased ischemic stroke infarct size after cerebral ischemia-reperfusion, and exacerbated pulmonary inflammatory hemorrhage following lipopolysaccharide-induced acute lung injury. Analysis of MFN2 SNPs in the iSPAAR study (Identification of SNPs Predisposing to Altered ALI Risk) identified a significant association between MFN2 and 28-day mortality in patients with acute respiratory distress syndrome.
Conclusions:
Mfn2 preserves mitochondrial phenotypes in megakaryocytes and platelets and influences platelet life span, function, and outcomes of stroke and lung injury.
Insights
Mitofusin-2 (MFN2) is crucial for platelet health, affecting mitochondrial function, lifespan, and bleeding disorders. MFN2 deficiency impacts stroke and lung injury outcomes.
Area of Science:
- Mitochondrial biology and platelet function.
- Genetics and hematology.
Background:
- Single-nucleotide polymorphisms (SNPs) in the mitofusin-2 (MFN2) gene are linked to reduced platelet MFN2 expression and lower platelet counts.
- The MFN2 gene encodes a mitochondrial fusion protein vital for cellular processes.
Purpose of the Study:
- To investigate the role of MFN2 in megakaryocyte and platelet biology.
- To understand how MFN2 variants influence platelet function and disease.
Main Methods:
- Generated mice with megakaryocyte/platelet-specific MFN2 deletion (Mfn2-/-).
- Isolated human megakaryocytes and platelets from individuals with specific MFN2 genotypes.
- Assessed mitochondrial morphology, function, and platelet activation ex vivo and in vivo.
Main Results:
- Mfn2 deficiency led to fragmented mitochondria in megakaryocytes and altered platelet function, including reduced mitochondrial membrane potential and increased phosphatidylserine exposure.
- Mfn2-/- mice exhibited reduced platelet counts, shorter platelet lifespan, prolonged bleeding times, and altered stroke and acute lung injury outcomes.
- Human platelets with the T/T genotype for rs1474868 showed reduced MFN2 protein and impaired mitochondrial function.
Conclusions:
- MFN2 plays a critical role in maintaining mitochondrial integrity and function in megakaryocytes and platelets.
- MFN2 influences platelet lifespan, activation, and contributes to the pathophysiology of stroke and acute lung injury.
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