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V Mitev

Publications and source records attributed to V Mitev.

31 records · Page 2Linked to original sources
PubMed1995

Protein kinase C is not necessary for beta-casein gene induction by prolactin in HC11 mouse mammary cells.

HC11 mouse mammary cells cultured in the presence of insulin, cortisol and prolactin for 24 h accumulated beta-casein mRNA. When the specific inhibitor of protein kinase C, GF 109203 X, was added to the medium with the hormones, the accumulation of beta-casein mRNA was unaltered, although the protein kinase C activity was almost completely suppressed. This suggests that protein kinase C is not strictly necessary for prolactin to induce milk protein gene expression.

Animals↗
PubMed1994

Modulation of epidermal growth factor and keratinocyte growth factor effects on human keratinocyte growth by protein kinase C inhibitor, GF 109203X: comparison to fibroblast growth modulation.

In this study, epidermal growth factor (EGF), 20 ng/ml, and keratinocyte growth factor (KGF), 10 ng/ml, were able to stimulate human keratinocyte growth only in presence of GF 109203X 1 microM, a selective PKC inhibitor. This suggests that PKC negatively controls keratinocyte growth in response to EGF and KGF. On the other hand, EGF and KGF have no significant effect on PKC activity. In contrast, in human fibroblasts, EGF stimulated fibroblast growth in the presence or not of GF 109203X. Thus, EGF seems to stimulate fibroblast growth in a PKC independent manner. Moreover, EGF didn't modify significantly PKC activity in fibroblasts. KGF had no effect on fibroblasts. These results show differences in the interconnections between PKC and EGF transduction pathway in the modulation of human keratinocyte and fibroblast growth. Moreover, they especially demonstrate that PKC would negatively control human keratinocyte growth in response to EGF and also to KGF.

Adult↗
PubMed1994

Purification and characterization of casein kinase II from lactating rabbit mammary gland.

1. Highly purified 200 kDa casein kinase II from rabbit lactating mammary gland (MG-CK II) was obtained by means of a new purification procedure consisting of one phosphocellulose and three Monó Q steps. 2. Its Km for ATP was 2.22 microM and 0.57 mg/ml and 0.13 mg/ml for partially dephosphorylated casein and phosvitin respectively. Stathmine was also suitable as substrate. 2-aminopurine and 6-dimethylaminopurine inhibited efficiently MG-CK II (Ki = 5 and 1 mM respectively). 3. MG-CK II autophosphorylated on its alpha-, alpha'- and beta-subunits. The beta-subunit autophosphorylation was enhanced in presence of exogenous substrate. Its modulation was highly dependent on ATP concentration. 4. The effects of basic compounds which affected dramatically the phosphorylation of dephosphorylated casein in presence of various ATP concentrations were reported.

Adenosine Triphosphate↗
PubMed1994

Enhanced casein kinase II activity in metastatic melanoma.

The benign dermal nevus can be transformed into malignant melanoma. The possibility that the transformation process is accompanied with enhanced casein kinase II (CK II) activity was investigated. The tissue samples were obtained by incisional biopsy, homogenized and ultracentrifuged. The supernatant was injected onto a Mono Q column. CK II was monitored with [gamma-32P]GTP and its specific substrate RRREEETEEE. The CK II stimulators, spermine and polylysine, the inhibitors heparin, quercetin, poly (Glu-Tyr) 4:1 and 2,3-bisphosphoglycerate were used for identification. CK II activity in metastatic melanoma samples was about 2.5-fold higher than in dermal nevus. These results support our hypothesis that CK II takes a central role in the non-transformed and transformed skin proliferation.

Amino Acid Sequence↗
PubMed1994

Purification and characterization of two casein kinase type II isozymes from bovine brain gray matter.

Highly purified casein kinase II (CK II) isozymes from bovine brain gray matter (BBGM) were obtained by means of a new purification procedure consisting of one phosphocellulose and three Mono-Q steps. The phosphocellulose eluate showed two BBGM-CK II activities. The first minor component (BBGM-CK IIa) was eluted with 0.9 M NaCl and the major component was eluted at 1.1 M NaCl (BBGM-CK IIb). The protein complexes responsible for these two activities were comprised of three subunits, i.e., alpha (40 kDa), alpha' (38 kDa), and beta (28 kDa), with various subunit ratios. The two isozymes displayed the same behavior on Superose 12 fast protein liquid chromatographic gel filtration and sucrose density centrifugation. BBGM-CK IIa and b showed chromatographic and biochemical differences including differing Km for ATP and GTP and Ki for heparin and 2,3-bisphosphoglycerate. The properties of the main peak (BBGM-CK IIb) were studied in detail. The stimulatory effect of Mg2+, Mn2+, and Co2+ was highly dependent both on the nature of the substrate and on ionic type and concentration. It is surprising that with phosvitin as substrate, BBGM-CK IIb was fully active even in the absence of Mg2+ and NaCl. The inhibitory effect of heparin and the stimulatory effects of NaCl, KCl, spermine, and polylysine were highly dependent on the ionic strength, buffer type, and substrate. BBGM-CK II isozymes phosphorylated stathmine in the presence of polylysine, but the requirement for polybasic compounds was not absolute, as is the case with calmodulin and clathrin beta-light chain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Differential modulation of human fibroblast and keratinocyte growth by the protein kinase C inhibitor GF 109203X.

Protein kinase C (PKC) is known to be involved in cellular proliferation and differentiation. In this work, we have investigated the effects of a novel PKC inhibitor, GF 109203X, on normal human fibroblast and keratinocyte growth. GF 109203X selectively inhibited PKC activity extracted from either fibroblasts (IC50 = 0.01 microM) or keratinocytes (IC50 = 0.4 microM). The inhibitory effects of GF 109203X on total PKC activity and Ca(2+)-independent PKC activity were similar. Nevertheless, in keratinocytes Ca(2+)-independent PKC activity represented 95% of total PKC activity, whereas in fibroblasts it corresponded to only 32% of total PKC activity. GF 109203X also inhibited a cellular function related to PKC activity in living fibroblasts and keratinocytes; it blocked the inhibitory effect of 12-O-tetradecanoylphorbol-13-acetate on 125I-epidermal growth factor binding. GF 109203X inhibited fibroblast growth, in terms of tritiated thymidine incorporation and cell counts, in a dose-dependent manner. We also observed that GF 109203X at 1 microM inhibited serum stimulation of expression of mRNA for c-fos and c-jun, which are usually involved in cellular proliferation. These results suggest that PKC stimulates fibroblast growth. In contrast, GF 109203X stimulated keratinocyte growth. We also observed that GF 109203X inhibited c-fos and c-jun mRNA expression in these cells. In fact, in keratinocytes these proto-oncogenes would be involved in the cellular differentiation process rather than in cellular proliferation. This suggests that the inhibition of PKC favors keratinocyte proliferation probably by inhibiting their differentiation. Thus, using GF 109203X, we show that PKC is involved differently in human fibroblast and keratinocyte growth.

Adolescent↗
PubMed1994

[The role of a growth-related cytosol protein kinase in the pathogenesis of psoriasis].

A Growth-related protein kinase's activity was studied in clinically affected and unaffected psoriatic epidermis. This activity was about 3 fold higher in clinically affected skin. Additionally, the unaffected psoriatic epidermis shows higher activity than the normal one. We conclude that the Growth-related protein kinase might be involved in the pathogenesis of psoriasis.

Acne Vulgaris↗