ABIN1 (Q478) is Required to Prevent Hematopoietic Deficiencies through Regulating Type I IFNs Expression

Area of Science:

• Immunology
• Hematology
• Molecular Biology

Background:

• A20-binding inhibitor of NF-κB activation (ABIN1) is a polyubiquitin-binding protein involved in cell death and immune responses.
• ABIN1 is located on chromosome 5q, a region frequently deleted in 5q minus syndrome, a type of myelodysplastic syndrome (MDS).
• The specific role of ABIN1 in MDS pathogenesis is currently unknown.

Purpose of the Study:

• To investigate the role of ABIN1 in myelodysplastic syndromes.
• To elucidate the mechanism by which ABIN1 regulates hematopoietic function.

Main Methods:

• Generation of mice with a mutation in the polyubiquitin-binding site of ABIN1 (Abin1^Q478H/Q478H).
• Assessment of hematopoietic parameters, including anemia, thrombocytopenia, and megakaryocyte dysplasia.
• Analysis of necroptosis pathway involvement (RIPK1, RIPK3, MLKL) and type I interferon (IFN-I) signaling.

Main Results:

• Abin1^Q478H/Q478H mice developed MDS-like conditions with anemia, thrombocytopenia, megakaryocyte dysplasia, extramedullary hematopoiesis, and bone marrow failure.
• While Abin1^Q478H/Q478H cells were sensitive to necroptosis, only anemia and splenomegaly were partially rescued by RIPK3 deficiency, suggesting a necroptosis-independent RIPK3 function.
• Abin1^Q478H/Q478H mice showed elevated type I interferon (IFN-I) expression; blocking IFN-I signaling ameliorated the observed hematopoietic defects.

Conclusions:

• The polyubiquitin-binding function of ABIN1 is critical for preventing hematopoietic deficiencies.
• ABIN1 regulates hematopoietic homeostasis, at least in part, through the suppression of type I interferon expression.
• These findings highlight ABIN1 as a potential therapeutic target in MDS.