Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice

Viola Lorenz, Haley Ramsey, Zhi Jian Liu, Joseph Italiano, Karin Hoffmeister, Sihem Bihorel, Donald Mager, Zhongbo Hu, William B. Slayton, Benjamin T. Kile, Martha Sola-Visner, Francisca Ferrer-Marin

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Congenital amegakaryocytic thrombocytopaenia (CAMT) is a disorder caused by c-MPL mutations that impair thrombopoietin (TPO) signalling, resulting in a near absence of megakaryocytes (MKs). While this phenotype is consistent in adults, neonates with CAMT can present with severe thrombocytopaenia despite normal MK numbers. To investigate this, we characterized MKs and platelets in newborn c-MPL -/- mice. Liver MKs in c-MPL -/- neonates were reduced in number and size compared with wild-type (WT) age-matched MKs, and exhibited ultrastructural abnormalities not found in adult c-MPL -/- MKs. Platelet counts were lower in c-MPL -/- compared with WT mice at birth and did not increase over the first 2 weeks of life. In vivo biotinylation revealed a significant reduction in the platelet half-life of c-MPL -/- newborn mice (P2) compared with age-matched WT pups, which was not associated with ultrastructural abnormalities. Genetic deletion of the pro-apoptotic Bak did not rescue the severely reduced platelet half-life of c-MPL -/- newborn mice, suggesting that it was due to factors other than platelets entering apoptosis early. Indeed, adult GFP+ (green fluorescent protein transgenic) platelets transfused into thrombocytopenic c-MPL -/- P2 pups also had a shortened lifespan, indicating the importance of cell-extrinsic factors. In addition, neonatal platelets from WT and c-MPL -/- mice exhibited reduced P-selectin surface expression following stimulation compared with adult platelets of either genotype, and platelets from c-MPL -/- neonates exhibited reduced glycoprotein IIb/IIIa (GPIIb/IIIa) activation in response to thrombin compared with age-matched WT platelets. Taken together, our findings indicate that c-MPL deficiency is associated with abnormal maturation of neonatal MKs and developmental stage-specific defects in platelet function.

Original languageEnglish
Pages (from-to)2322-2333
Number of pages12
JournalThrombosis and Haemostasis
Volume117
Issue number12
DOIs
Publication statusPublished - 1 Jan 2017

Keywords

  • animal models
  • bone marrow
  • megakaryocytes
  • platelet physiology
  • thrombocytopaenia

Cite this

Lorenz, V., Ramsey, H., Liu, Z. J., Italiano, J., Hoffmeister, K., Bihorel, S., ... Ferrer-Marin, F. (2017). Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice. Thrombosis and Haemostasis, 117(12), 2322-2333. https://doi.org/10.1160/TH17-06-0433
Lorenz, Viola ; Ramsey, Haley ; Liu, Zhi Jian ; Italiano, Joseph ; Hoffmeister, Karin ; Bihorel, Sihem ; Mager, Donald ; Hu, Zhongbo ; Slayton, William B. ; Kile, Benjamin T. ; Sola-Visner, Martha ; Ferrer-Marin, Francisca. / Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice. In: Thrombosis and Haemostasis. 2017 ; Vol. 117, No. 12. pp. 2322-2333.
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title = "Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice",
abstract = "Congenital amegakaryocytic thrombocytopaenia (CAMT) is a disorder caused by c-MPL mutations that impair thrombopoietin (TPO) signalling, resulting in a near absence of megakaryocytes (MKs). While this phenotype is consistent in adults, neonates with CAMT can present with severe thrombocytopaenia despite normal MK numbers. To investigate this, we characterized MKs and platelets in newborn c-MPL -/- mice. Liver MKs in c-MPL -/- neonates were reduced in number and size compared with wild-type (WT) age-matched MKs, and exhibited ultrastructural abnormalities not found in adult c-MPL -/- MKs. Platelet counts were lower in c-MPL -/- compared with WT mice at birth and did not increase over the first 2 weeks of life. In vivo biotinylation revealed a significant reduction in the platelet half-life of c-MPL -/- newborn mice (P2) compared with age-matched WT pups, which was not associated with ultrastructural abnormalities. Genetic deletion of the pro-apoptotic Bak did not rescue the severely reduced platelet half-life of c-MPL -/- newborn mice, suggesting that it was due to factors other than platelets entering apoptosis early. Indeed, adult GFP+ (green fluorescent protein transgenic) platelets transfused into thrombocytopenic c-MPL -/- P2 pups also had a shortened lifespan, indicating the importance of cell-extrinsic factors. In addition, neonatal platelets from WT and c-MPL -/- mice exhibited reduced P-selectin surface expression following stimulation compared with adult platelets of either genotype, and platelets from c-MPL -/- neonates exhibited reduced glycoprotein IIb/IIIa (GPIIb/IIIa) activation in response to thrombin compared with age-matched WT platelets. Taken together, our findings indicate that c-MPL deficiency is associated with abnormal maturation of neonatal MKs and developmental stage-specific defects in platelet function.",
keywords = "animal models, bone marrow, megakaryocytes, platelet physiology, thrombocytopaenia",
author = "Viola Lorenz and Haley Ramsey and Liu, {Zhi Jian} and Joseph Italiano and Karin Hoffmeister and Sihem Bihorel and Donald Mager and Zhongbo Hu and Slayton, {William B.} and Kile, {Benjamin T.} and Martha Sola-Visner and Francisca Ferrer-Marin",
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Lorenz, V, Ramsey, H, Liu, ZJ, Italiano, J, Hoffmeister, K, Bihorel, S, Mager, D, Hu, Z, Slayton, WB, Kile, BT, Sola-Visner, M & Ferrer-Marin, F 2017, 'Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice' Thrombosis and Haemostasis, vol. 117, no. 12, pp. 2322-2333. https://doi.org/10.1160/TH17-06-0433

Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice. / Lorenz, Viola; Ramsey, Haley; Liu, Zhi Jian; Italiano, Joseph; Hoffmeister, Karin; Bihorel, Sihem; Mager, Donald; Hu, Zhongbo; Slayton, William B.; Kile, Benjamin T.; Sola-Visner, Martha; Ferrer-Marin, Francisca.

In: Thrombosis and Haemostasis, Vol. 117, No. 12, 01.01.2017, p. 2322-2333.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice

AU - Lorenz, Viola

AU - Ramsey, Haley

AU - Liu, Zhi Jian

AU - Italiano, Joseph

AU - Hoffmeister, Karin

AU - Bihorel, Sihem

AU - Mager, Donald

AU - Hu, Zhongbo

AU - Slayton, William B.

AU - Kile, Benjamin T.

AU - Sola-Visner, Martha

AU - Ferrer-Marin, Francisca

PY - 2017/1/1

Y1 - 2017/1/1

N2 - Congenital amegakaryocytic thrombocytopaenia (CAMT) is a disorder caused by c-MPL mutations that impair thrombopoietin (TPO) signalling, resulting in a near absence of megakaryocytes (MKs). While this phenotype is consistent in adults, neonates with CAMT can present with severe thrombocytopaenia despite normal MK numbers. To investigate this, we characterized MKs and platelets in newborn c-MPL -/- mice. Liver MKs in c-MPL -/- neonates were reduced in number and size compared with wild-type (WT) age-matched MKs, and exhibited ultrastructural abnormalities not found in adult c-MPL -/- MKs. Platelet counts were lower in c-MPL -/- compared with WT mice at birth and did not increase over the first 2 weeks of life. In vivo biotinylation revealed a significant reduction in the platelet half-life of c-MPL -/- newborn mice (P2) compared with age-matched WT pups, which was not associated with ultrastructural abnormalities. Genetic deletion of the pro-apoptotic Bak did not rescue the severely reduced platelet half-life of c-MPL -/- newborn mice, suggesting that it was due to factors other than platelets entering apoptosis early. Indeed, adult GFP+ (green fluorescent protein transgenic) platelets transfused into thrombocytopenic c-MPL -/- P2 pups also had a shortened lifespan, indicating the importance of cell-extrinsic factors. In addition, neonatal platelets from WT and c-MPL -/- mice exhibited reduced P-selectin surface expression following stimulation compared with adult platelets of either genotype, and platelets from c-MPL -/- neonates exhibited reduced glycoprotein IIb/IIIa (GPIIb/IIIa) activation in response to thrombin compared with age-matched WT platelets. Taken together, our findings indicate that c-MPL deficiency is associated with abnormal maturation of neonatal MKs and developmental stage-specific defects in platelet function.

AB - Congenital amegakaryocytic thrombocytopaenia (CAMT) is a disorder caused by c-MPL mutations that impair thrombopoietin (TPO) signalling, resulting in a near absence of megakaryocytes (MKs). While this phenotype is consistent in adults, neonates with CAMT can present with severe thrombocytopaenia despite normal MK numbers. To investigate this, we characterized MKs and platelets in newborn c-MPL -/- mice. Liver MKs in c-MPL -/- neonates were reduced in number and size compared with wild-type (WT) age-matched MKs, and exhibited ultrastructural abnormalities not found in adult c-MPL -/- MKs. Platelet counts were lower in c-MPL -/- compared with WT mice at birth and did not increase over the first 2 weeks of life. In vivo biotinylation revealed a significant reduction in the platelet half-life of c-MPL -/- newborn mice (P2) compared with age-matched WT pups, which was not associated with ultrastructural abnormalities. Genetic deletion of the pro-apoptotic Bak did not rescue the severely reduced platelet half-life of c-MPL -/- newborn mice, suggesting that it was due to factors other than platelets entering apoptosis early. Indeed, adult GFP+ (green fluorescent protein transgenic) platelets transfused into thrombocytopenic c-MPL -/- P2 pups also had a shortened lifespan, indicating the importance of cell-extrinsic factors. In addition, neonatal platelets from WT and c-MPL -/- mice exhibited reduced P-selectin surface expression following stimulation compared with adult platelets of either genotype, and platelets from c-MPL -/- neonates exhibited reduced glycoprotein IIb/IIIa (GPIIb/IIIa) activation in response to thrombin compared with age-matched WT platelets. Taken together, our findings indicate that c-MPL deficiency is associated with abnormal maturation of neonatal MKs and developmental stage-specific defects in platelet function.

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KW - bone marrow

KW - megakaryocytes

KW - platelet physiology

KW - thrombocytopaenia

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Lorenz V, Ramsey H, Liu ZJ, Italiano J, Hoffmeister K, Bihorel S et al. Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice. Thrombosis and Haemostasis. 2017 Jan 1;117(12):2322-2333. https://doi.org/10.1160/TH17-06-0433