Selective deficiency in protein kinase C isoenzyme expression and inadequacy in mitogen-activated protein kinase activation in cord blood T cells.
The biochemical basis for the reduced lymphokine production by neonatal T cells compared with adult T cells remains poorly defined. Previous studies have raised the possibility that neonatal T cells could be deficient in their ability to transmit signals via protein kinase (PK) C. We now report that while PKC-dependent activation of the mitogen-activated protein (MAP) kinases, c-Jun N-terminal protein kinase and the extracellular signal-regulated protein kinase (ERK)1/ERK2, was deficient in cord blood T cells compared with adult blood T cells, marked activation of the MAP kinases in cord blood T cells was achieved via PKC-independent means. Consistent with a deficiency in the signalling capability of PKC, cord blood T cells were selectively deficient in the expression of PKC beta I, epsilon, theta and zeta. Stimulation of cord blood T cells resulted in a time-dependent increase in PKC expression, with increases detectable by 4 h. This was accompanied by an enhancement in MAP kinase activation via PKC-dependent means. These novel data suggest that an inadequacy in PKC-MAP kinase signalling may be responsible, at least in part, for the phenotype of cord blood T cells.
Hii
Charles S T
CS
Department of Immunopathology, Women's and Children's Hospital, 72 King William Road, North Adelaide, Adelaide 5006, Australia. chii01@mail.staff.adelaide.edu.au
Costabile
Maurizio
M
Mayne
George C
GC
Der
Channing J
CJ
Murray
Andrew W
AW
Ferrante
Antonio
A
D004789:Enzyme Activation; D005260:Female; D005312:Fetal Blood / Q000166:cytology / Q000201:enzymology*; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011247:Pregnancy; D011493:Protein Kinase C / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000201:enzymology*
D007527:Isoenzymes; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases