Calpeptin increases the activity of upstream stimulatory factor and induces high level globin gene expression in erythroid cells.
Differentiation of erythroid cells is regulated by cell signaling pathways including those that change the intracellular concentration of calcium. Calcium-dependent proteases have been shown previously to process and regulate the activity of specific transcription factors. We show here that the protein levels of upstream stimulatory factor (USF) increase during differentiation of murine erythroleukemia (MEL) cells. USF was subject to degradation by the Ca(2+)-dependent protease m-calpain in undifferentiated but not in differentiated MEL cells. Treatment of MEL cells with the specific calpain inhibitor calpeptin increased the levels of USF and strongly induced expression of the adult alpha- and beta-globin genes. The induction of globin gene expression was associated with an increase in the association of USF and RNA po ly mer ase II with regulatory elements of the beta-globin gene locus. Calpeptin also induced high level alpha- and beta-globin gene expression in primary CD71-positive erythroid progenitor cells. The combined data suggest that inhibition of calpain activity is required for erythroid differentiation-associated increase in globin gene expression.
Lin
I-Ju
IJ
Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
Zhou
Zhuo
Z
Crusselle-Davis
Valerie J
VJ
Moghimi
Babak
B
Gandhi
Kunjal
K
Anantharaman
Archana
A
Pantic
Dorjan
D
Huang
Suming
S
Jayandharan
Giridhararao
G
Zhong
Li
L
Srivastava
Arun
A
Bungert
Jörg
J
D000818:Animals; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism; D002454:Cell Differentiation; D004151:Dipeptides / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D041905:Erythroid Cells / Q000166:cytology* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics* / Q000378:metabolism; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D051189:Murinae; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism; D051720:Upstream Stimulatory Factors / Q000235:genetics / Q000378:metabolism*
D004151:Dipeptides; D004791:Enzyme Inhibitors; D051720:Upstream Stimulatory Factors; C071482:calpeptin; D005914:Globins; D012319:RNA Polymerase II; D002154:Calpain; C449000:m-calpain