Deficiency of thioredoxin-interacting protein results in age-related thrombocytopenia due to megakaryocyte oxidative stress.

Background: Platelets are generated from megakaryocytes (MKs), mainly located in the bone marrow (BM). Megakaryopoiesis can be affected by genetic disorders, metabolic diseases, and aging. The molecular mechanisms underlying platelet count regulation have not been fully elucidated.

Objectives: In the present study, we investigated the role of thioredoxin-interacting protein (TXNIP), a protein that regulates cellular metabolism in megakaryopoiesis, using a Txnip mouse model.

Methods: Wild-type (WT) and Txnip mice (2-27-month-old) were studied. BM-derived MKs were analyzed to investigate the role of TXNIP in megakaryopoiesis with age. The global transcriptome of BM-derived CD41 megakaryocyte precursors (MkPs) of WT and Txnip mice were compared. The CD34 hematopoietic stem cells isolated from human cord blood were differentiated into MKs.

Results: Txnip mice developed thrombocytopenia at 4 to 5 months that worsened with age. During ex vivo megakaryopoiesis, Txnip MkPs remained small, with decreased levels of MK-specific markers. Critically, Txnip MkPs exhibited reduced mitochondrial reactive oxygen species, which was related to AKT activity. Txnip MkPs also showed elevated glycolysis alongside increased glucose uptake for ATP production. Total RNA sequencing revealed enrichment for oxidative stress- and apoptosis-related genes in differentially expressed genes between Txnip and WT MkPs. The effects of TXNIP on MKs were recapitulated during the differentiation of human cord blood-derived CD34 hematopoietic stem cells.

Conclusion: We provide evidence that the megakaryopoiesis pathway becomes exhausted with age in Txnip mice with a decrease in terminal, mature MKs that response to thrombocytopenic challenge. Overall, this study demonstrates the role of TXNIP in megakaryopoiesis, regulating mitochondrial metabolism.