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Updated: Apr 21, 2026
Isolation of Mouse Megakaryocyte Progenitors
Published on: May 20, 2021
Cytosolic carboxypeptidase CCP6 is required for megakaryopoiesis by modulating Mad2 polyglutamylation
Buqing Ye1, Chong Li1, Zhao Yang2
1Key Laboratory of Infection and Immunity of CAS, Center for Laboratory Animal Research, Center for Biological Imaging, Key Laboratory of RNA Biology and Beijing Noncoding RNA Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Abstract:
Bone marrow progenitor cells develop into mature megakaryocytes (MKs) to produce platelets for hemostasis and other physiological functions. However, the molecular mechanisms underlying megakaryopoiesis are not completely defined. We show that cytosolic carboxypeptidase (CCP) 6 deficiency in mice causes enlarged spleens and increased platelet counts with underdeveloped MKs and dysfunctional platelets. The prominent phenotypes of CCP6 deficiency are different from those of CCP1-deficient mice. We found that CCP6 and tubulin tyrosine ligase-like family (TTLL) members TTLL4 and TTLL6 are highly expressed in MKs. We identify Mad2 (mitotic arrest deficient 2) as a novel substrate for CCP6 and not CCP1. Mad2 can be polyglutamylated by TTLL4 and TTLL6 to modulate the maturation of MKs. CCP6 deficiency causes hyperglutamylation of Mad2 to promote activation of Aurora B, leading to suppression of MK maturation. We reveal that Mad2 polyglutamylation plays a critical role in the regulation of megakaryopoiesis.
Insights
Cytosolic carboxypeptidase 6 (CCP6) deficiency in mice impairs megakaryopoiesis, leading to underdeveloped megakaryocytes and dysfunctional platelets. This study identifies Mad2 polyglutamylation as a key regulator of platelet production.
Area of Science:
- Hematology
- Molecular Biology
- Cell Biology
Background:
- Megakaryopoiesis, the process of platelet production from bone marrow progenitor cells, is crucial for hemostasis.
- The precise molecular mechanisms governing megakaryopoiesis remain incompletely understood.
- Cytosolic carboxypeptidases (CCPs) are enzymes involved in protein modification, but their specific roles in megakaryopoiesis are largely undefined.
Purpose of the Study:
- To investigate the role of cytosolic carboxypeptidase 6 (CCP6) in megakaryopoiesis.
- To identify novel substrates and regulatory pathways of CCP6 in megakaryocyte development.
- To elucidate the molecular mechanisms by which CCP6 deficiency impacts platelet production and function.
Main Methods:
- Utilized a mouse model deficient in CCP6 to study megakaryopoiesis.
- Examined megakaryocyte morphology, platelet counts, and platelet function in CCP6-deficient mice.
- Investigated the expression of CCP6 and tubulin tyrosine ligase-like (TTLL) family members in megakaryocytes.
- Identified and characterized Mad2 as a novel substrate of CCP6 using biochemical and cellular assays.
- Analyzed the effects of CCP6 deficiency on Mad2 polyglutamylation and Aurora B kinase activity.
Main Results:
- CCP6 deficiency in mice resulted in splenomegaly, increased platelet counts, underdeveloped megakaryocytes, and dysfunctional platelets.
- CCP6, TTLL4, and TTLL6 were found to be highly expressed in megakaryocytes.
- Mad2 was identified as a novel substrate for CCP6, and its polyglutamylation by TTLL4 and TTLL6 was shown to modulate megakaryocyte maturation.
- CCP6 deficiency led to Mad2 hyperglutamylation, promoting Aurora B kinase activation and suppressing megakaryocyte maturation.
- The findings highlight a critical role for Mad2 polyglutamylation in regulating megakaryopoiesis.
Conclusions:
- CCP6 plays a significant role in regulating megakaryopoiesis through the modulation of Mad2 polyglutamylation.
- Dysregulation of Mad2 polyglutamylation, influenced by CCP6 activity, leads to impaired megakaryocyte maturation and platelet dysfunction.
- This study uncovers a novel molecular pathway involving CCP6, Mad2, and Aurora B in the intricate process of platelet production.
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