Mitochondrial PIP3-binding protein FUNDC2 supports platelet survival via AKT signaling pathway

Area of Science:

• Mitochondrial biology
• Hematology
• Cell death pathways

Background:

• Platelets undergo apoptosis, a programmed cell death, influenced by mitochondrial regulation.
• The pro-survival protein BCL-xL on mitochondria is critical for determining platelet lifespan.
• Understanding platelet survival mechanisms is crucial for treating platelet-related diseases.

Purpose of the Study:

• To identify novel proteins involved in regulating platelet survival and apoptosis.
• To elucidate the molecular mechanism by which FUNDC2 influences platelet lifespan.
• To explore the therapeutic potential of targeting the FUNDC2 pathway in platelet disorders.

Main Methods:

• Utilized FUNDC2 knockout mice to study platelet apoptosis.
• Investigated the interaction of FUNDC2 with mitochondrial lipids (PIP3).
• Analyzed the phosphorylation status of key signaling proteins (AKT, BAD) and BCL-xL expression.

Main Results:

• FUNDC2 knockout mice displayed increased platelet apoptosis and thrombocytopenia, particularly under hypoxic conditions.
• FUNDC2 directly binds to PIP3 via its N-terminal motif.
• FUNDC2 deficiency impaired AKT and BAD phosphorylation in a PIP3/PI3K-dependent manner, reducing BCL-xL levels and platelet survival.
• FUNDC2 deficiency shortened platelet lifespan under stress.

Conclusions:

• The outer mitochondrial membrane protein FUNDC2 is essential for platelet survival.
• The FUNDC2/AKT/BCL-xL signaling axis regulates platelet apoptosis at the mitochondrial level.
• This pathway provides new insights into the pathogenesis of thrombocytopenia and other platelet-related diseases.