Megakaryocyte polyploidization is associated with a functional gene amplification.
It is believed that polyploidy induces an orchestrated increase in gene expression. To know whether all alleles remain functional during megakaryocyte polyploidization, we used a well-established fluorescence in situ hybridization technique which allows one to simultaneously detect pre-mRNAs and assess ploidy level in a single cell. All alleles of GPIIb, GPIIIa, VWF, beta-actin, hsp70, c-mpl, Fli-1, and FOG-1 genes are transcriptionally active in megakaryocytes from 4N to 32N. All X chromosomes in male cells are transcriptionally active but only half of them are transcriptionally active in female megakaryocytes, as revealed by the transcriptional activity of the GATA-1 gene. Nuclear untranslated XIST RNA accumulates on the inactivated X chromosomes, indicating that they are subjected to a normal inactivation process. Altogether, our results demonstrate that megakaryocyte polyploidization results in a functional gene amplification whose likely function is an increase in protein synthesis parallel with cell enlargement.
Raslova
Hana
H
INSERM U362, and Centre National de la Recherche Scientifique (CNRS) UMR 1599, Institut Gustave Roussy, Villejuif, France.
Roy
Lydia
L
Vourc'h
Claire
C
Le Couedic
Jean Pierre
JP
Brison
Olivier
O
Metivier
Didier
D
Feunteun
Jean
J
Kroemer
Guido
G
Debili
Najet
N
Vainchenker
William
W
D000483:Alleles; D002454:Cell Differentiation / Q000235:genetics; D041321:Chromosomes, Human, X; D005260:Female; D005784:Gene Amplification; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008533:Megakaryocytes / Q000378:metabolism*; D015539:Platelet Activation / Q000235:genetics; D011123:Polyploidy; D015138:RNA, Nuclear / Q000032:analysis; D014158:Transcription, Genetic
D015138:RNA, Nuclear