Ubiquitin/proteasome-rich particulate cytoplasmic structures (PaCSs) in the platelets and megakaryocytes of ANKRD26-related thrombocytopenia

Summary

ANKRD26-related thrombocytopenia (ANKRD26-RT) is an autosomaldominant thrombocytopenia caused by mutations in the 5’UTR of the ANKRD26 gene. ANKRD26-RT is characterised by dysmegakaryopoiesis and an increased risk of leukaemia. PaCSs are novel particulate cytoplasmic structures with selective immunoreactivity for polyubiquitinated proteins and proteasome that have been detected in a number of solid cancers, in the epithelia of Helicobacter pylori gastritis and related preneoplastic lesions, and in the neutrophils of Schwachman- Diamond syndrome, a genetic disease with neutropenia and increased leukaemia risk. We searched for PaCSs in blood cells from 14 consecutive patients with ANKRD26-RT. Electron microscopy combined with immunogold staining for polyubiquitinated proteins, 20S and 19S proteasome showed PaCSs in most ANKRD26-RT platelets, as in a restricted minority of platelets from healthy controls and from subjects with other inherited or immune thrombocytopenias. In ANKRD26-RT platelets, the PaCS amount exceeded that of control platelets by a factor of 5 (p<0.0001). Immunoblotting showed that the higher PaCS number was associated with increased amounts of polyubiquitinated proteins and proteasome in ANKRD26-RT platelets. PaCSs were also extensively represented in ANKRD26-RT megakaryocytes, but not in healthy control megakaryocytes, and were absent in other ANKRD26-RT and control blood cells. Therefore, large amounts of PaCSs are a characteristic feature of ANKRD26-RT platelets and megakaryocytes, although these novel cell components are also present in a small subpopulation of normal platelets. The widespread presence of PaCSs in inherited diseases with increased leukaemia risk, as well as in solid neoplasms and their preneoplastic lesions, suggests a link of these structures with oncogenesis.

Keywords

ANKRD26-related thrombocytopenia - inherited thrombocytopenia - ubiquitin/proteasome system - dysmegakaryopoiesis

• References

• 1 Pippucci T, Savoia A, Perrotta S. et al. Mutations in the 5’ UTR of ANKRD26, the Ankirin repeat domain 26 gene, cause an autosomal-dominant form of inherited thrombocytopenia, THC2. Am J Hum Gen 2011; 88: 115-120.
• 2 Noris P, Perrotta S, Seri M. et al. Mutations in ANKRD26 are responsible for a frequent form of inherited thrombocytopenia: analysis of 78 patients from 21 families. Blood 2011; 117: 6673-6680.
• 3 Liu XF, Bera TK, Liu LJ. et al. A primate-specific POTE-actin fusion protein plays a role in apoptosis. Apoptosis 2009; 14: 1237-1244.
• 4 Necchi V, Sommi P, Ricci V, Solcia E. In vivo accumulation of Helicobacter pylori products, NOD1, ubiquitinated proteins and proteasome in a novel cytoplasmic structure. PLoS One 2010; 05: e9716.
• 5 Necchi V, Sommi P, Vanoli A. et al. Proteasome particle-rich structures are widely present in human epithelial neoplasms: correlative light, confocal and electron microscopy study. PLoS One 2011; 08: e21317.
• 6 Necchi V, Minelli A, Sommi P. et al. Ubiquitin-proteasome-rich cytoplasmic structures in neutrophils of patients with Schwachman-Diamond syndrome. Haematologica. 2012 Epub ahead of print.
• 7 Boocock GR, Morrison JA, Popovic M. et al. Mutations in SBDS are associated with Shwachman-Diamond syndrome. Nat Genet 2003; 33: 97-101.
• 8 Balduini CL, Pecci A, Savoia A. Recent advances in the understanding and management of MYH9-related inherited thrombocytopenias. Br J Haematol 2011; 154: 161-174.
• 9 Noris P, Perrotta S, Bottega R. et al. Clinical and laboratory features of 103 patients from 42 Italian families with inherited thrombocytopenia derived from the monoallelic Ala156Val mutation of GPIbα (Bolzano mutation). Haematologica 2012; 97: 82-88.
• 10 Provan D, Stasi R, Newland AC. et al. International consensus report on the investigation and management of primary immune thrombocytopenia. Blood 2010; 115: 168-186.
• 11 Pecci A, Canobbio I, Balduini A. et al. Pathogenetic mechanisms of hematological abnormalities of patients with MYH9 mutations. Hum Mol Genet 2005; 14: 3169-3178.
• 12 Pecci A, Malara A, Badalucco S. et al. Megakaryocytes of patients with MYH9-related thrombocytopenia present an altered proplatelet formation. Thromb Haemost 2009; 102: 90-96.
• 13 Balduini A, Malara A, Pecci A. et al. Proplatelet formation in heterozygous Bernard-Soulier syndrome type Bolzano. J Thromb Haemost 2009; 07: 478-484.
• 14 Necchi V, Candusso ME, Tava F. et al. Intracellular, intercellular, and stromal invasion of gastric mucosa, preneoplastic lesions, and cancer by Helicobacter pylori. Gastroenterology 2007; 132: 1009-1023.
• 15 Mason KD, Carpinelli MR, Fletcher JI. et al. Programmed anuclear cell death delimits platelet life span. Cell 2007; 128: 1173-1186.
• 16 Jesenberger V, Jentsch S. Deadly encounter: ubiquitin meets apoptosis. Nat Rev Mol Cell Biol 2002; 03: 112-121.
• 17 Dror Y, Freedman MH. Shwachman-Diamond syndrome marrow cells show abnormally increased apoptosis mediated through the Fas pathway. Blood 2001; 97: 3011-3016.
• 18 Suber T, Rosen A. Apoptotic cell blebs: repositories of autoantigens and contributors to immune context. Arthritis Rheum 2009; 60: 2216-2219.
• 19 Pitzer F, Dantes A, Fuchs T. et al. Removal of proteasomes from the nucleus and their accumulation in apoptotic blebs during programmed cell death. FEBS Lett 1996; 394: 47-50.
• 20 Viala J, Chaput C, Boneca IG. et al. Nod1 responds to peptidogycan delivered by the Helicobacter pylori cag pathogenicity island. Nat Immunol 2004; 05: 1166-1174.
• 21 Hatakeyama M. Oncogenic mechanisms of the Helicobacter pylori CagA protein. Nat Rev Cancer 2004; 04: 688-694.
• 22 Sahab ZJ, Hall MD, Zhang L. et al. Tumor suppressor RARRES1 regulates DLG2, PP2A, VCP, EB1, and Ankrd26. J Cancer 2010; 02: 14-22.
• 23 Bera TK, Saint Fleur A, Lee Y. et al. POTE paralogs are induced and differentially expressed in many cancers. Cancer Res 2006; 66: 52-56.