Pro-B-cell-specific transcription and proapoptotic function of protein kinase Ceta.
Using a subtractive cloning scheme on cDNA prepared from primary pro-B and pre-B cells, we identified several genes whose products regulate apoptosis. We further characterized one of these genes, encoding protein kinase Ceta (PKCeta). PKCeta transcripts were readily detected in pro-B cells but were absent in pre-B cells. Although both a full-length and a truncated form of PKCeta were detectable in bone marrow pro-B cells, transition to the pre-B-cell stage was associated with increased relative levels of truncated PKCeta. We found that PKCeta is proteolyzed in apoptotic lymphocytes, generating a kinase-active fragment identical to the truncated form which is capable of inducing apoptosis when expressed in a pro-B cell line. Caspase-3 can generate an identical PKCeta cleavage product in vitro, and caspase inhibitors prevent the generation of this product during apoptosis in transfected cell lines. Inducible overexpression of either the full-length or truncated form of PKCeta results in cell cycle arrest at the G(1)/S transition. These results suggest that the expression and proteolytic activation of PKCeta play an important role in the regulation of cell division and cell death during early B-cell development.
Graduate Program in Immunology, The Johns Hopkins University School of Public Health, Baltimore, Maryland 21205, USA.
T A
TA
Morrow
S A
SA
Muljo
J
J
Zhang
J M
JM
Hardwick
M S
MS
Schlissel
D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D001402:B-Lymphocytes / Q000166:cytology* / Q000201:enzymology; D053148:Caspase 3; D020169:Caspases / Q000502:physiology; D002453:Cell Cycle; D019070:Cell Lineage; D018076:DNA, Complementary / Q000235:genetics; D004790:Enzyme Induction; D018507:Gene Expression Regulation, Developmental; D006410:Hematopoiesis / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000201:enzymology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009928:Organ Specificity; D010446:Peptide Fragments / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000096:biosynthesis; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013382:Subtraction Technique; D014158:Transcription, Genetic; D014162:Transfection
D018076:DNA, Complementary; D018398:Homeodomain Proteins; D007527:Isoenzymes; D010446:Peptide Fragments; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; C064658:RAG-1 protein; C081975:protein kinase C eta; D011493:Protein Kinase C; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases