Differential degradation of intracellular proteins in human skin fibroblasts of mitotic and mitomycin-C (MMC)-induced postmitotic differentiation states in vitro.
Rates of degradation of short- and long-lived proteins were analysed in homogeneous fibroblast cultures of mitotic or mitomycin C (MMC)-induced postmitotic states. When the highly mitotic MFII type cells--the major cell type of so called "early passage" or "young" fibroblasts--differentiate into MFIII type cells, the last mitotic fibroblast type, and further into MMC-induced postmitotic fibroblasts, the degradation of short-lived proteins increases by a factor of 1.4, resulting in significantly reduced half-lives of these proteins in the postmitotic fibroblasts. From the highly mitotic MFII to the final postmitotic PMFVI-type cells via the intermediates MFIII, PMFIV and PMFV, the half lives (t1/2) of short-lived proteins decrease by a total of 122 min in average, from 362 to 240 min. Degradation of long-lived proteins did not change significantly from cell type MFII to PMFVI. As analysed by two-dimensional (2D)-gel electrophoresis the half-lives of the mitotic and postmitotic cell-type-specific proteins except one, protein PIVa (33 kDa; Pi 5.0), range between 33.2 h and 62.9 h. Protein PIVa, the first protein specific for postmitotic cells, is initially expressed 18 h after the induction of the postmitotic state by mitomycin C (MMC) and has a half-life of approximately 66 min. This may indicate that protein PIVa could function as one possible regulatory factor controlling the postmitotic differentiation state.
Rodemann
H P
HP
Developmental Biology Unit, University of Bielefeld, Federal Republic of Germany.
D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002648:Child; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008937:Mitomycins / Q000494:pharmacology*; D008938:Mitosis / Q000187:drug effects*; D011506:Proteins / Q000032:analysis / Q000378:metabolism* / Q000502:physiology
D008937:Mitomycins; D011506:Proteins