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A unique talin antigenic determinant and anomalous megakaryocyte talin
distribution associated with abnormal platelet formation in the Wistar
Furth rat
CW Jackson, NK Hutson, SA Steward and PE Stenberg
Department of Hematology/Oncology, St Jude Children's Research Hospital,
Memphis, TN 38101.
Rats of the Wistar Furth (WF) strain have hereditary macrothrombocytopenia
with decreased platelet alpha-granule proteins. The autosomal recessive
pattern of inheritance of the large mean platelet volume (MPV) phenotype
and platelet alpha-granule protein deficiencies suggest that a component
common to both formation of platelet alpha-granules and subdivision of
megakaryocyte cytoplasm into platelets is quantitatively or qualitatively
abnormal in WF megakaryocytes and platelets. We examined WF platelets for
such an abnormality using electrophoretic and immunologic analyses. Rabbit
antiserum prepared against WF rat platelets and absorbed with Wistar rat
platelets recognized a major 235-Kd band, and minor bands of WF rat
platelets ranging from 200 to 130 Kd, not present in immunoblots of Wistar,
Sprague-Dawley, or Long-Evans rat platelets. The minor bands were labeled
with affinity-isolated antibody to the 235-Kd band, indicating that all
bands contained the same unique antigenic site. The 235-Kd antigen had the
same mobility as rat platelet talin identified with a platelet antitalin
antibody. Activation of calcium-dependent proteases during Triton X-100
extraction caused conversion of the 235- Kd antigen into a major fragment
of 200 Kd and minor fragments ranging to 115 Kd, identical in mobility to
fragments of rat platelet talin produced in the same samples. The absorbed
anti-WF platelet antiserum also detected a 235-Kd antigen in WF lung,
kidney, and small intestine by immunoblotting. Finally, the 235-Kd antigen
unique to WF rats was immunoprecipitated from Triton X-100 supernatants of
WF platelets with an antitalin monoclonal antibody (MoAb). These data
indicate that the unique antigenic site is on WF talin. Examination of
talin distribution in Wistar megakaryocytes showed localization beneath the
plasma membrane, on the cytosolic face of demarcation membranes, associated
with alpha-granule membranes, and diffusely throughout the cytoplasm.
Although WF megakaryocytes showed the same general distribution pattern,
some differences were apparent. In contrast to membrane systems of the
Wistar rat, the large membrane complexes in WF megakaryocytes contained
little or no talin. In addition, approximately half of WF megakaryocytes
showed an increased peripheral localization of talin, often associated with
membrane blebs, with decreased talin in the cytoplasmic interior. The
association of the unique talin antigenic determinant and anomalous
megakaryocyte talin distribution with abnormal platelet formation in WF
rats suggests that talin is abnormal in this rat strain and that talin
plays an important role in subdivision of megakaryocyte cytoplasm into
platelets.
Volume 79,
Issue 7,
pp. 1729-1737,
04/01/1992
Copyright © 1992 by The American Society of Hematology
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This article has been cited by other articles:
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P. E. Stenberg, R. J. Barrie, T. I. Pestina, S. A. Steward, J. T. Arnold, A. K. Murti, N. K. Hutson, and C. W. Jackson
Prolonged Bleeding Time With Defective Platelet Filopodia Formation in the Wistar Furth Rat
Blood,
March 1, 1998;
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[Abstract]
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L Hemmings, D. Rees, V Ohanian, S. Bolton, A. Gilmore, B Patel, H Priddle, J. Trevithick, R. Hynes, and D. Critchley
Talin contains three actin-binding sites each of which is adjacent to a vinculin-binding site
J. Cell Sci.,
January 11, 1996;
109(11):
2715 - 2726.
[Abstract]
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