[Role of antiapoptotic Bcl-X(L) in megakaryocyte differentiation and maturation].
OBJECTIVE
To investigate the role of antiapoptotic Bcl-x(L) protein in megakaryocyte differentiation and maturation.


METHODS
RNA interference was used to block the expression of Bcl-x(L) when K562 cells were induced to differentiate into megakaryocyte (CD61 + cells) by PDBu, and the expression of Bcl-x(L) was evaluated with flow cytometry and reverse transcription polymerase chain reaction (RT-PCR). The CD34 + cell fraction was positively isolated by using the MiniMACS system from normal bone marrow. Immunochemical staining and flow cytometry were used to detect the expression of Bcl-x(L) in the differentiation (CD41 + cells) of CD34 + cells induced by trombopoietin (TPO).


RESULTS
Among K562 cells induced by PDBu, the percentage of CD6L + cells rapidly increased in 24 hours and maintained at a high positive level in 72 hours. When exposured to si-Bcl-x(L), the percentage of CD6 1 + cells only slightly increased in 72 hours. The expression of Bcl-x(L) mRNA was significantly decreased after transfection compared with that of control group, and Bcl-x(L) protein expression decreased correspondingly. After the CD34 + bone marrow cells having been treated with TPO for 5 days to 20 days, the Bcl-x(L)-megakaryocytes increased as the culture time prolonged, and there was a strong expression of Bcl-x(L) in immature megakaryocyte and an obviously decreased expression in degenerating megakaryocytes maturation.


CONCLUSIONS
Increased expression of antiapoptotic Bcl-x(L) may be essential to mature megakaryocyte. The down-regulation of antiapoptotic Bcl-x(L) in mature megakaryocyte may be crucial to platelets formation.
Zhang
Lei
L
State Key Laboratory of Experimental Hematology, Hospital of Blood Disease, Institute of Hematology, CAMS and PUMC, Tianjin 300020, China.
Yang
Ren-chi
RC
Lu
Shi-hong
SH
Liu
Bin
B
Ren
He
H
Han
Zhi-bo
ZB
Han
Zhong-chao
ZC
D002454:Cell Differentiation; D006801:Humans; D020014:K562 Cells; D008533:Megakaryocytes / Q000502:physiology*; D034622:RNA Interference; D051020:bcl-X Protein / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
D051020:bcl-X Protein