Association of Factor V Secretion with Protein Kinase B Signaling in Platelets from Horses with Atypical Equine Thrombasthenia

J. W. Norris, M. Pombo, E. Shirley, G. Blevins, Fern Tablin

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Background: Two congenital bleeding diatheses have been identified in Thoroughbred horses: Glanzmann thrombasthenia (GT) and a second, novel diathesis associated with abnormal platelet function in response to collagen and thrombin stimulation. Hypothesis/Objectives: Platelet dysfunction in horses with this second thrombasthenia results from a secretory defect. Animals: Two affected and 6 clinically normal horses. Methods: Ex vivo study. Washed platelets were examined for (1) expression of the αIIb-β3 integrin; (2) fibrinogen binding capacity in response to ADP and thrombin; (3) secretion of dense and α-granules; (4) activation of the mammalian target of rapamycin (mTOR)-protein kinase B (AKT) signaling pathway; and (5) cellular distribution of phosphatidylinositol-4-phosphate-3-kinase, class 2B (PIK3C2B) and SH2 containing inositol-5′-phosphatase 1 (SHIP1). Results: Platelets from affected horses expressed normal amounts of αIIb-β3 integrin and bound fibrinogen normally in response to ADP, but bound 80% less fibrinogen in response to thrombin. α-granules only released 50% as much Factor V as control platelets, but dense granules released their contents normally. Protein kinase B (AKT) phosphorylation was reduced after thrombin activation, but mTOR Complex 2 (mTORC2) and phosphoinositide-dependent kinase 1 (PDK1) signaling were normal. SH2-containing inositol-5'-phosphatase 1 (SHIP1) did not localize to the cytoskeleton of affected platelets and was decreased overall consistent with reduced AKT phosphorylation. Conclusions and clinical significance: Defects in fibrinogen binding, granule secretion, and signal transduction are unique to this thrombasthenia, which we designate as atypical equine thrombasthenia.

Original languageEnglish (US)
Pages (from-to)1387-1394
Number of pages8
JournalJournal of Veterinary Internal Medicine
Volume29
Issue number5
DOIs
StatePublished - Sep 1 2015

Fingerprint

Thrombasthenia
Proto-Oncogene Proteins c-akt
Factor V
protein kinases
thrombin
Horses
fibrinogen
Blood Platelets
secretion
granules
horses
Thrombin
Fibrinogen
integrins
Disease Susceptibility
Phosphatidylinositol-4-Phosphate 3-Kinase
phosphorylation
phosphotransferases (kinases)
Integrins
Adenosine Diphosphate

Keywords

  • AKT
  • Bleeding Diathesis
  • Factor V
  • Horse

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Association of Factor V Secretion with Protein Kinase B Signaling in Platelets from Horses with Atypical Equine Thrombasthenia. / Norris, J. W.; Pombo, M.; Shirley, E.; Blevins, G.; Tablin, Fern.

In: Journal of Veterinary Internal Medicine, Vol. 29, No. 5, 01.09.2015, p. 1387-1394.

Research output: Contribution to journalArticle

@article{f114f96d87c4430bbc8256583856094f,
title = "Association of Factor V Secretion with Protein Kinase B Signaling in Platelets from Horses with Atypical Equine Thrombasthenia",
abstract = "Background: Two congenital bleeding diatheses have been identified in Thoroughbred horses: Glanzmann thrombasthenia (GT) and a second, novel diathesis associated with abnormal platelet function in response to collagen and thrombin stimulation. Hypothesis/Objectives: Platelet dysfunction in horses with this second thrombasthenia results from a secretory defect. Animals: Two affected and 6 clinically normal horses. Methods: Ex vivo study. Washed platelets were examined for (1) expression of the αIIb-β3 integrin; (2) fibrinogen binding capacity in response to ADP and thrombin; (3) secretion of dense and α-granules; (4) activation of the mammalian target of rapamycin (mTOR)-protein kinase B (AKT) signaling pathway; and (5) cellular distribution of phosphatidylinositol-4-phosphate-3-kinase, class 2B (PIK3C2B) and SH2 containing inositol-5′-phosphatase 1 (SHIP1). Results: Platelets from affected horses expressed normal amounts of αIIb-β3 integrin and bound fibrinogen normally in response to ADP, but bound 80{\%} less fibrinogen in response to thrombin. α-granules only released 50{\%} as much Factor V as control platelets, but dense granules released their contents normally. Protein kinase B (AKT) phosphorylation was reduced after thrombin activation, but mTOR Complex 2 (mTORC2) and phosphoinositide-dependent kinase 1 (PDK1) signaling were normal. SH2-containing inositol-5'-phosphatase 1 (SHIP1) did not localize to the cytoskeleton of affected platelets and was decreased overall consistent with reduced AKT phosphorylation. Conclusions and clinical significance: Defects in fibrinogen binding, granule secretion, and signal transduction are unique to this thrombasthenia, which we designate as atypical equine thrombasthenia.",
keywords = "AKT, Bleeding Diathesis, Factor V, Horse",
author = "Norris, {J. W.} and M. Pombo and E. Shirley and G. Blevins and Fern Tablin",
year = "2015",
month = "9",
day = "1",
doi = "10.1111/jvim.13595",
language = "English (US)",
volume = "29",
pages = "1387--1394",
journal = "Journal of Veterinary Internal Medicine",
issn = "0891-6640",
publisher = "Wiley-Blackwell",
number = "5",

}

TY - JOUR

T1 - Association of Factor V Secretion with Protein Kinase B Signaling in Platelets from Horses with Atypical Equine Thrombasthenia

AU - Norris, J. W.

AU - Pombo, M.

AU - Shirley, E.

AU - Blevins, G.

AU - Tablin, Fern

PY - 2015/9/1

Y1 - 2015/9/1

N2 - Background: Two congenital bleeding diatheses have been identified in Thoroughbred horses: Glanzmann thrombasthenia (GT) and a second, novel diathesis associated with abnormal platelet function in response to collagen and thrombin stimulation. Hypothesis/Objectives: Platelet dysfunction in horses with this second thrombasthenia results from a secretory defect. Animals: Two affected and 6 clinically normal horses. Methods: Ex vivo study. Washed platelets were examined for (1) expression of the αIIb-β3 integrin; (2) fibrinogen binding capacity in response to ADP and thrombin; (3) secretion of dense and α-granules; (4) activation of the mammalian target of rapamycin (mTOR)-protein kinase B (AKT) signaling pathway; and (5) cellular distribution of phosphatidylinositol-4-phosphate-3-kinase, class 2B (PIK3C2B) and SH2 containing inositol-5′-phosphatase 1 (SHIP1). Results: Platelets from affected horses expressed normal amounts of αIIb-β3 integrin and bound fibrinogen normally in response to ADP, but bound 80% less fibrinogen in response to thrombin. α-granules only released 50% as much Factor V as control platelets, but dense granules released their contents normally. Protein kinase B (AKT) phosphorylation was reduced after thrombin activation, but mTOR Complex 2 (mTORC2) and phosphoinositide-dependent kinase 1 (PDK1) signaling were normal. SH2-containing inositol-5'-phosphatase 1 (SHIP1) did not localize to the cytoskeleton of affected platelets and was decreased overall consistent with reduced AKT phosphorylation. Conclusions and clinical significance: Defects in fibrinogen binding, granule secretion, and signal transduction are unique to this thrombasthenia, which we designate as atypical equine thrombasthenia.

AB - Background: Two congenital bleeding diatheses have been identified in Thoroughbred horses: Glanzmann thrombasthenia (GT) and a second, novel diathesis associated with abnormal platelet function in response to collagen and thrombin stimulation. Hypothesis/Objectives: Platelet dysfunction in horses with this second thrombasthenia results from a secretory defect. Animals: Two affected and 6 clinically normal horses. Methods: Ex vivo study. Washed platelets were examined for (1) expression of the αIIb-β3 integrin; (2) fibrinogen binding capacity in response to ADP and thrombin; (3) secretion of dense and α-granules; (4) activation of the mammalian target of rapamycin (mTOR)-protein kinase B (AKT) signaling pathway; and (5) cellular distribution of phosphatidylinositol-4-phosphate-3-kinase, class 2B (PIK3C2B) and SH2 containing inositol-5′-phosphatase 1 (SHIP1). Results: Platelets from affected horses expressed normal amounts of αIIb-β3 integrin and bound fibrinogen normally in response to ADP, but bound 80% less fibrinogen in response to thrombin. α-granules only released 50% as much Factor V as control platelets, but dense granules released their contents normally. Protein kinase B (AKT) phosphorylation was reduced after thrombin activation, but mTOR Complex 2 (mTORC2) and phosphoinositide-dependent kinase 1 (PDK1) signaling were normal. SH2-containing inositol-5'-phosphatase 1 (SHIP1) did not localize to the cytoskeleton of affected platelets and was decreased overall consistent with reduced AKT phosphorylation. Conclusions and clinical significance: Defects in fibrinogen binding, granule secretion, and signal transduction are unique to this thrombasthenia, which we designate as atypical equine thrombasthenia.

KW - AKT

KW - Bleeding Diathesis

KW - Factor V

KW - Horse

UR - http://www.scopus.com/inward/record.url?scp=84940935040&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84940935040&partnerID=8YFLogxK

U2 - 10.1111/jvim.13595

DO - 10.1111/jvim.13595

M3 - Article

VL - 29

SP - 1387

EP - 1394

JO - Journal of Veterinary Internal Medicine

JF - Journal of Veterinary Internal Medicine

SN - 0891-6640

IS - 5

ER -