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 language | English (US) |
|---|---|
| Pages (from-to) | 1387-1394 |
| Number of pages | 8 |
| Journal | Journal of Veterinary Internal Medicine |
| Volume | 29 |
| Issue number | 5 |
| DOIs | |
| State | Published - Sep 1 2015 |
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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 journal › Article
}
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 -