Bcakground

Thrombopoietin (Tpo) , is a key regulator of megakaryocytopoiesis and thrombopoiesis. It is principally produced in the liver and is bound and with human and rat Tpo, respectively. It is an 80-85 kDa protein that consists of an N-terminal domain with homology to Erythropoietin (Epo) and a internalized by the receptor Tpo R/c-mpl. Defects in the Tpo-Tpo R signaling pathway are associated with a variety of platelet disorders (1-3). The 356 amino acid (aa) mouse Tpo precursor is cleaved to yield the 335 aa mature protein. Mature mouse Tpo shares 71% and 81% aa sequence homology C-terminal domain that contains multiple N-linked and O-linked glycosylation sites (4, 5). Tissue specific alternate splicing of mouse Tpo generates multiple isoforms with internal deletions, insertions, and/or C-terminal substitutions (6). Tpo promotes the differentiation, proliferation, and maturation of MK and their progenitors (4, 5, 7). Several other cytokines can promote these functions as well but only in cooperation with Tpo (8, 9). Notably, IL-3 independently induces MK development, although its effects are restricted to early in the MK lineage (8, 9). Tpo additionally promotes platelet production, aggregation, ECM adhesion, and activation (10-12). It is cleaved by platelet-derived thrombin following Arg191 within the C-terminal domain and subsequently at other sites upon extended digestion . Full length Tpo and shorter forms circulate in the plasma (4, 5). The C-terminal domain is not required for binding to Tpo R or inducing MK growth and differentiation (5). Aside from its hematopoietic effects, Tpo is expressed in the brain where it promotes the apoptosis of hypoxia-sensitized neurons and inhibits neuronal differentiation by blocking NGF-induced signaling .

Reference

1. Deutsch, V.R. and A. Tomer (2006) Br. J. Haematol. 134:453.

2. Kaushansky, K. (2005) J. Clin. Invest. 115:3339.

3. Li, J. et al. (1999) Br. J. Haematol. 106:345.

4. Bartley, T.D. et al. (1994) Cell 77:1117.

5. de Sauvage, F.J. et al. (1994) Nature 369:533.

6. Marcucci, R. and M. Romano (2008) Biochim. Biophys. Acta 1782:427.

7. Kaushansky, K. et al. (1994) Nature 369:568.

8. Kaushansky, K. et al. (1995) Proc. Natl. Acad. Sci. 92:3234.

8. Broudy, V.C. et al. (1995) Blood 85:1719.

10. Lok, S.I. et al. (1994) Nature 369:565.

11. Chen, J. et al. (1995) Blood 86:4054.

12. VOda, A. et al. (1996) Blood 87:4664.

Specifications

Synonyms	THCYT1; THPO; thrombopoietin nirs variant 1; Thrombopoietin; Tpo; TPOMKCSF; MKCSF; MK-CSF
Accession #	P40226
Source	Human embryonic kidney cell, HEK293-derived mouse TPO protein
Source	Ser22-Thr356
Predicted Moleucular weight	35.6 kDa

Components and Storage

Formulation	Solution protein
	Dissolved in sterile PBS buffer.
	This solution can be diluted into other aqueous buffers. Centrifuge the vial prior to opening.
Storage and Stability	Avoid repeated freeze-thaw cycles.
	It is recommended that the protein be aliquoted for optimal storage.
	12 months from date of receipt, -20 to -70 °C as supplied.
Shipping	Shipping with dry ice

Quality

Purity	> 95%, determined by SDS-PAGE
Endotoxin Level	<0.010 EU per 1 ug of the protein by the LAL method
Activity	Measured in a cell proliferation assay using MO7e human megakaryocytic leukemic cells.
Activity	The EC50 for this effect is 0.04-2.4 ng/mL.

SDS-PAGE

Bioactivity

Documents

Mouse TPO