SEARCH · PubMed Health

Results for “Cell Proliferation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

PubMed2004

Modifiers of the jumonji mutation downregulate cyclin D1 expression and cardiac cell proliferation.

Cell proliferation is an important factor in various developmental processes in tissue morphogenesis, and is strictly regulated spatiotemporally. jumonji (jmj) deficient mice with a C3H/He background show hyperproliferation of cardiac myocytes and die probably of the phenotype around embryonic day 11.5. Analyses of the abnormalities revealed that repression of cyclin D1 expression by jmj is necessary for downregulation of cardiac myocyte proliferation. On the other hand, jmj mutant mice with a BALB/c background die around E14.5, suggesting that genetic background modifies hyperproliferation in the heart and timing of lethality. Here, we demonstrated that the hyperproliferation was not observed, and that cell proliferation and expression of cyclin D1 were downregulated properly in the cardiac ventricles of jmj mutant mice with a BALB/c background. These results suggest the modifier(s) of the jmj mutation can downregulate cardiac cell proliferation by repressing cyclin D1 expression in the same way as jmj.

Animals↗

PubMed1981

Patterns of cell proliferation and cell migration in the Sézary syndrome.

The patterns of cell proliferation and cell migration were studied in three patients with the Sezary syndrome using autoradiographic techniques. Cell labeling patterns following pulse labeling with tritiated thymidine in vivo indicated that Sezary cells proliferate actively in skin and in lymph nodes but that few if any Sezary cells proliferate in the peripheral blood. In two of the patients serial samples were obtained. Label dilution patterns in skin and blood over time suggested that circulating Sezary cells originated in extracutaneous sites where cells were proliferating more rapidly than in the skin. Cells labeled in extracutaneous sites of proliferation appear rapidly in the blood, and their transit time through the peripheral blood compartment is short. Circulating Sezary cells may then be deposited in the skin where they resume proliferation at a low rate. Thus, while Sezary cells proliferate in both cutaneous and extracutaneous sites, proliferation appears to be more rapid in extracutaneous sites such as lymph nodes. This suggests that trials of systemic therapeutic approaches should be undertaken.

Autoradiography↗

PubMed2005

Phosphorylation of phosphoprotein enriched in astrocytes (PEA-15) regulates extracellular signal-regulated kinase-dependent transcription and cell proliferation.

Cell cycle progression is dependent on the nuclear localization and transcriptional effects of activated extracellular signal-regulated kinase (ERK)1 and ERK2 mitogen-activated protein (MAP) kinases (ERK1/2). Phosphoprotein enriched in astrocytes (PEA-15) binds ERK1/2 and inhibits their nuclear localization, thus blocking cell proliferation. Here, we report that phosphorylation of PEA-15 blocks its interaction with ERK1/2 in vitro and in vivo and that phosphorylation of both Ser104 and Ser116 is required for this effect. Using phosphomimetic and nonphosphorylatable mutants of PEA-15, we found that PEA-15 phosphorylation abrogates its capacity to block the nuclear localization and transcriptional activities of ERK1/2; this phosphorylation therefore enables the proliferation of cells that express high levels of PEA-15. Additionally, we report that PEA-15 phosphorylation can modulate nontranscriptional activities of ERK1/2, such as the modulation of the affinity of integrin adhesion receptors. Finally, we used a novel anti-phospho-specific PEA-15 antibody to establish that PEA-15 is phosphorylated in situ in normal mammary epithelium. These results define a novel posttranslational mechanism for controlling the subcellular localization of ERK1/2 and for specifying the output of MAP kinase signaling.

Active Transport, Cell Nucleus↗

PubMed2004

Inhibition of cell proliferation and cell cycle progression by specific inhibition of basal JNK activity: evidence that mitotic Bcl-2 phosphorylation is JNK-independent.

The c-Jun NH(2)-terminal kinase (JNK) subgroup of mitogen-activated protein kinases has been implicated largely in stress responses, but an increasing body of evidence has suggested that JNK also plays a role in cell proliferation and survival. We examined the effect of JNK inhibition, using either SP600125 or specific antisense oligonucleotides, on cell proliferation and cell cycle progression. SP600125 was selective for JNK in vitro and in vivo versus other kinases tested including ERK, p38, cyclin-dependent protein kinase 1 (CDK1), and CDK2. SP600125 inhibited JNK activity and KB-3 cell proliferation with the same dose dependence, suggesting that inhibition of proliferation was a direct consequence of JNK inhibition. Inhibition of proliferation by SP600125 was associated with an increase in the G(2)-M and apoptotic fractions of cells but was not associated with p53 or p21 induction. Antisense oligonucleotides to JNK2 but not JNK1 caused highly significant inhibition of cell proliferation. Wild-type mouse fibroblasts responded similarly with proliferation inhibition and apoptosis induction, whereas c-jun(-/-) fibroblasts were refractory to the effects of SP600125, suggesting that JNK signaling to c-Jun is required for cell proliferation. Studies in synchronized KB-3 cells indicated that SP600125 delayed transit time through S and G(2)-M phases. Correspondingly, JNK activity increased in late S phase and peaked in late G(2) phase. During synchronous mitotic progression, cyclin B levels increased concomitant with phosphorylation of c-Jun, H1 histone, and Bcl-2. In the presence of SP600125, mitotic progression was prolonged, and c-Jun phosphorylation was inhibited, but neither H1 nor Bcl-2 phosphorylation was inhibited. However, the CDK inhibitor roscovitine inhibited mitotic Bcl-2 phosphorylation. These results indicate that JNK, and more specifically the JNK2 isoform, plays a key role in cell proliferation and cell cycle progression. In addition, conclusive evidence is presented that a kinase other than JNK, most likely CDK1 or a CDK1-regulated kinase, is responsible for mitotic Bcl-2 phosphorylation.

Anthracenes↗

PubMedDate not supplied

Effect of TGF-beta 1, TGF-alpha, and EGF on cell proliferation and cell death in rat ventral prostatic epithelial cells in culture.

A tissue culture system for rat prostatic epithelial cells was developed, and the effect of epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and transforming growth factor beta 1 (TGF-beta 1) on these cells was evaluated. The primary culture was prepared by DNAse/collagenase dissociation of minced ventral prostates. Cells were initially plated in RPMI-1640 medium containing 10% fetal bovine serum to allow the preferential attachment of stromal cells. Twenty-four hours later, the unattached epithelial cells were replated in WAJC-404 medium supplemented with insulin (5 micrograms/ml), transferrin (5 micrograms/ml), and selenious acid (5 ng/ml). Bovine pituitary extract (BPE) (30 micrograms/ml), EGF (10 ng/ml), and TGF-beta 1 (0, 0.1, and 1.0 ng/ml) were added either alone or in combination according to experimental requirements. The rate of cell proliferation was assessed by counting the total cell number and by [3H]thymidine incorporation. Prostatic epithelial cells exhibited a bell-shaped growth curve in a span of 7-8 days, with a growth peak at day 3 or 4 of culture. Treatment of cells with EGF or TGF-alpha resulted in a concentration-dependent increase in cell growth, whereas addition of TGF-beta 1 into the culture resulted in an inhibition of cell proliferation that could be reversed with increasing concentrations of EGF. Cell death was assessed using the terminal deoxynucleotidyl transferase (TdT)-mediated immunoperoxidase-digoxigenin nick end labeling technique and the trypan blue exclusion test. Epithelial cells cultured in media containing EGF had the lowest incidence of cell death. Cells cultured in the absence of EGF demonstrated a marked increase in cells undergoing cell death. The addition of TGF-beta 1 into the EGF-depleted medium caused a further increase of cell death. These results indicated that cell proliferation and cell death in rat prostatic epithelial cells in culture could be modulated by EGF and TGF-beta 1. The former stimulated cell proliferation and prevented cell death, whereas the latter inhibited proliferation in the presence or absence of EGF and induced cell death.

Animals↗

PubMedDate not supplied

Cell proliferation and cell loss in nodule-in-nodule hepatocellular carcinoma.

BACKGROUND/AIMS: In order to clarify the significance of the balance between cell proliferation and cell loss during the progression of hepatocellular carcinoma, 16 operative specimens of nodule-in-nodule hepatocellular carcinoma were investigated. METHODOLOGY: In 16 specimens, cell proliferation was evaluated by the expression of Ki-67 nuclear antigen, and cell loss was also examined by the method of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The expressions of p53 protein, bcl-2 protein and Fas antigen were also investigated to clarify the relationship between their expression and cell kinetics. RESULTS: The Ki-67 labeling index of the inner nodules was higher than that for the outer nodules (18.9% vs. 7.2%; p < 0.05) and the TUNEL labeling index of the inner nodules was also higher than that for the outer nodules (12.8% vs. 6.6%; p < 0.05). The increasing rate of the Ki-67 labeling index from Edmondson's grade I to II was 3.9 +/- 3.0, that from grade II to III was 3.9 +/- 2.4, while the increasing rate of the TUNEL labeling index from grade I to II was 2.7 +/- 0.3 and that from grade II to III was 1.7 +/- 0.2 (p < 0.05). p53 Protein was observed in 5 cases, while bcl-2 protein was found in 4 cases in the border area of the inner nodule. However, Fas antigen was found in none of the examined cases. Regarding the Ki-67 positive rate in the inner nodule, the Ki-67 positive rate in the p53 protein positive cases was significantly higher than that in the negative cases (30.3 +/- 15.4 vs. 11.9 +/- 9.2; p < 0.05). However, the TUNEL labeling index was not affected by the expression of those proteins. CONCLUSIONS: This study suggested that tumor progression depends on a disturbance in the cell kinetic balance caused not by a decrease in the absolute amount of cell loss but in the chaotic balance between cell loss and cell proliferation.

Apoptosis↗

PubMed1995

Microvessel density, endothelial cell proliferation and tumour cell proliferation in human colorectal adenocarcinomas.

BACKGROUND: Thymidine incorporation studies performed in animal tumour models, revealed major differences in endothelial cell proliferation when tumour tissue was compared with normal tissue. The fraction of proliferating endothelial cells is reported to be increased by a factor of 30 to 40 in tumour tissue. PATIENTS AND METHODS: To make it possible to analyze the endothelial cell proliferation in human tumours, an immunohistochemical double staining technique comprising CD31, an endothelial cell marker, and Ki-67, a proliferation marker, was developed. Endothelial cell proliferation was analysed in 21 primary human colorectal adenocarcinomas and in the adjacent mucosa. RESULTS: Proliferating endothelial cells were found throughout the entire carcinoma. The mean overall endothelial cell labeling index (ECLI) was 9.9% (range, 5.4-18.0), and the labeling index of endothelial cells in areas of intense neovascularisation was even higher. Mean ECLI in the vascular hot spots was 21.0% (range, 6.8-35.0), and the mean tumour cell labeling index (TCLI) in the maximally Ki-67 immunostained areas was 78.3% (range 47.0-89.7). In 14 of 21 carcinomas, these areas were predominantly found at the luminal margin of the tumour, as were the vascular hot spots. A significant positive correlation was found between tumour vascularity, measured in the vascular hot spots, and tumour cell proliferation, measured in the maximally Ki-67 immunostained areas (p < 0.05). To analyse this relation in more detail, microvessel density (MVD), TCLI and ECLI were determined per x400 microscopic field by scanning in sequence from the luminal tumour margin to the invasive tumour base. In all tumours, the pattern of the MVD per x400 field, from the luminal margin to the tumour base, was similar to that of the TCLI and ECLI. CONCLUSIONS: These findings confirm that the fraction of cycling endothelial cells is higher in human colorectal carcinoma than in the adjacent mucosa which suggests that endothelial cells are proliferating in most of the individual capillaries in tumour tissue. Regional differences in MVD correlate with differences in tumour cell proliferation in these tumours.

Adenocarcinoma↗

PubMed2006

Distribution of Notch1-expressing cells and proliferating cells in mouse vomeronasal organ.

Vomeronasal receptor neurons (VRNs) proliferate and differentiate continuously in the vomeronasal organ (VNO) throughout life. In adult mice, new VRNs are generated mainly in the marginal region, located in the boundary region between sensory and nonsensory epithelia. The Notch signaling pathway is involved in differentiation in the developing nervous system. To understand the Notch signaling pathway involved in generating VRNs, we focused on the relationship between the expression pattern of Notch1 and the localization of proliferating cells in both developing and regenerating mice VNO, and examined the Notch signaling pathway involved in the development of VNO by in situ hybridization of Notch1 and immunocytochemistry of 5-bromo-2'-deoxyuridine. During embryonic and neonatal development, proliferating cells and Notch1-expressing (+) cells were observed evenly throughout VNO. A large number of proliferating cells and Notch1 (+) cells were observed in embryonic VNO, but gradually decreased during development. The localization of proliferating cells was similar to that of Notch1 (+) cells at each developmental stage. In adult VNO, there are a few proliferating cells and Notch1 (+) cells, which were only in the marginal region of VNO. Seven days after removal of the accessory olfactory bulb (AOB), VRNs proliferated throughout VNO. Although the number of Notch1 (+) cells also increased in VNO, the majority of these were concentrated in the dorsal region of VNO, suggesting that it has two types of differentiating cell. These results suggest that Notch1 plays a role in the differentiation of VRNs during development and regeneration of VRNs after removal of AOB.

Animals↗

PubMed1988

Toxicity in uremia. 1. Correlation between PTH levels and depressed cell proliferation.

Cell proliferation is significantly depressed in uremia; to assess the influence of PTH on it, normal lymphocytes were cultured in presence of uremic patients' serum with low or high plasma PTH levels (Group A; PTH less than 2.5 ng/ml; Group B: PTH greater than 12 ng/ml), and serum of normal subjects (Group C). Cell proliferation was lowered by serum from both groups (p A vs C less than 0.004; p B vs C less than 0.001). However, the depressing effect was more evident when group B serum was employed (p A vs B less than 0.002).

Cell Division↗

PubMed1998

Macrophages, cell proliferation, and cell death in the human menstrual corpus luteum.

We studied the presence and numbers of macrophages in the different compartments of the human menstrual corpus luteum (CL) in relation to the proliferative activity and apoptosis in luteal cells. Macrophages were recognized by immunohistochemical demonstration of the lysosome-associated glycoprotein CD68, and proliferating cells by immunohistochemical detection of the cell cycle-related protein Ki67 and by counting mitotic cells. In general, changes in the number of macrophages were parallel to the functional activity of the CL. Macrophage numbers increased up to the end of the early luteal phase, remained relatively unchanged during the midluteal phase, and decreased at the late luteal phase. Furthermore, macrophages showed prominent morphological changes during the cycle. They showed round or elongated cytoplasm during the early and late luteal phases, and dendritic features in the midluteal phase. Proliferating cells were very abundant on Days 15-16 and showed a significant decrease thereafter. Most proliferating cells corresponded to stromal (mainly vascular) cells. However, about 5% of granulosa-lutein cells and about 15% of theca-lutein cells were proliferating during the early and midluteal phases. Regression of the CL at the late luteal phase was associated with both a decrease in the number of proliferating cells and an increase in the number of apoptotic cells, which were highly increased on Days 25-27 of the cycle. The number of macrophages was not related to cell proliferation nor to cell death during the luteal phase. The observed changes in both macrophage number and morphology suggest the existence of a bidirectional communication between macrophages and steroidogenic cells in the human CL, or regulation of both cell populations by similar mechanisms.

Apoptosis↗

PubMed1999

Reduced expression of (alpha)5(beta)1 integrin prevents spreading-dependent cell proliferation.

Cell adhesion to substratum results in the initiation of integrin signaling and an integrin-dependent organization of the cytoskeleton (cell spreading). To address the potential relationships between these events and cell proliferation, we transfected NRK fibroblasts with an antisense cDNA encoding a 1.3 kb ATG-spanning portion of (alpha)5 integrin subunit and obtained stable clones in which the surface expression of (alpha)5(beta)1 integrin was selectively reduced. (alpha)5-antisense NRK cells are less spread than the control transfectants, have poorly defined stress fibers, and an increased amount of cortical actin. The antisense clones remained anchorage-dependent, but they proliferated very slowly. Serum dose-response curves showed that they have an impaired response to mitogens. Importantly, cell spreading and stress fiber formation could be completely restored by plating the antisense cells on collagen, but cell spreading failed to rescue proliferation. These data indicate that cell spreading can be uncoupled from cell proliferation and that cytoskeletal organization is important for NRK cell proliferation because it enforces the proliferative effect of (alpha)5(beta)1 integrin. Our results also indicate that reduced surface expression of (alpha)5(beta)1 integrin is not sufficient to confer the anchorage-independent phenotype to nontransformed cells.

Animals↗

PubMed1995

[Cell proliferation and cell death (apoptosis) as indices differentiating malignant from benign gastrointestinal myogenic tumors].

We examined whether the determination of cell proliferation and cell death rates was useful in the differential diagnosis between benign and malignant myogenic tumors of gastrointestinal tract. As markers for cell proliferation and cell death, Ki-67 (MIB-1) positive rates or argyrophilic nucleolar organizer region (AgNOR) counts and apoptotic cell counts were determined in a total of 53 myogenic tumors comprising 36 leiomyomas and 17 leiomyosarcomas. Apoptotic cells were detected with the in situ nick end labeling method reported by Gavrieli in 1992 with modifications. Significant differences were observed in the Ki-67 positive rates (leiomyoma 1.8 +/- 1.4%, leiomyosarcoma 8.6 +/- 6.0%, p < 0.0001), in the mean AgNOR counts (leiomyoma 1.77 +/- 0.53, leiomyosarcomas 3.14 +/- 1.02, p < 0.0001), and in the apoptotic cell counts (median; leiomyoma 3.2, leiomyosarcoma 32.5 per 10(6) tumor cells, p < 0.005). All high grade sarcomas were picked up by the Ki-67 index of more than 7%, and almost all leiomyomas were thrown away by the AgNOR counts more than 3.0 within the low Ki-67 cases, which showed 81% of sensitivity and 97% of specificity. These results show that a combination use of Ki-67 and AgNOR is of use in the differential diagnosis between leiomyoma and leiomyosarcoma. Although a significant difference was also noted in apoptotic cell counts between these two categories, this seems not to be a practical index for the discrimination because apoptotic cell death is a rare event in gastrointestinal myogenic tumors.

Apoptosis↗

PubMed1996

Fibroblast growth factor 2 uses distinct signaling pathways for cell proliferation and cell shape changes in corneal endothelial cells.

PURPOSE: Fibroblast growth factor 2 (FGF-2) is not only a potent mitogen, it is a modulator for corneal endothelial cells. To define how the modulation activities of FGF-2 are mediated, we used pharmacologic inhibitors to examine the association of phospholipase C-gamma 1 (PLC-gamma) with FGF receptor or with cytoskeleton. METHODS: Cell proliferation was determined either by the incorporation of 3H-thymidine into DNA or by counting cell numbers in the absence or presence of the inhibitors. The protein expression was analyzed by immunoprecipitation and immunoblot analysis. Cell shape change was determined by phase-contrast microscopy. RESULTS: FGF-2 stimulated DNA synthesis, whereas genistein inhibited the FGF-2-mediated cell proliferation in a dose-dependent manner, regardless of the concentration of FGF-2. The PLC-gamma 1 specific antisense oligonucleotide primer was able to inhibit cell proliferation by 25% in the absence of FGF-2; however, the antisense primer was not able to override the action of FGF-2. Fibroblast growth factor receptor was phosphorylated on treatment of the cells with FGF-2; however, 24-hour treatment with the growth factor significantly reduced phosphorylation of the receptor. Phospholipase C gamma 1 appears to be abundant in cytoplasm in the absence and presence of FGF-2, and a minor portion of the molecule is translocated to membrane after treatment with FGF-2; genistein inhibited the translocation. When the cytoskeleton fraction of the normal and the modulated corneal endothelial cells was immunoprecipitated with PLC-gamma 1 antibodies, PLC-gamma 1, actin, and vinculin were coprecipitated in both cell cultures. Phospholipase C gamma 1 associated with cytoskeleton was phosphorylated on treatment of the cells with FGF-2. In the presence of FGF-2 of the modulated cells, cytochalasin B, which did not revert the modulated cell morphology, abolished the association of PLC-gamma 1 with actin and vinculin; colchicine, which did revert the modulated cell shape to the polygonal shape, did not block the association of these three molecules. Interestingly, colchicine slightly enhanced the stimulatory effect of FGF-2 on corneal endothelial proliferation in contrast to the effect of cytochalasin B, which slightly decreased the FGF-2 action on cell proliferation. CONCLUSIONS: The association of PLC-gamma 1 with cytoskeleton plays a role in cell proliferation, whereas the association of PLC-gamma 1 with actin and vinculin has no effect on cell shape changes. These findings indicate that FGF-2 appears to use distinct signaling pathways for cell proliferation and cell shape changes in corneal endothelial cells.

Animals↗

PubMed2005

Effects of distal cholesterol biosynthesis inhibitors on cell proliferation and cell cycle progression.

Cholesterol is a major lipid component of the plasma membrane in animal cells. In addition to its structural requirement, cholesterol is essential in cell proliferation and other cell processes. The aim of the present study was to elucidate the stringency of the requirement for cholesterol as a regulator of proliferation and cell cycle progression, compared with other sterols of the cholesterol biosynthesis pathway. Human promyelocytic HL-60 cells were cultured in cholesterol-free medium and treated with different distal inhibitors of cholesterol biosynthesis (zaragozic acid, SKF 104976, SR 31747, BM 15766, and AY 9944), which allow the synthesis of isoprenoid derivatives and different sets of sterol intermediates, but not cholesterol. The results showed that only the inhibition of sterol Delta7-reductase was compatible with cell proliferation. Blocking cholesterol biosynthesis upstream of this enzyme resulted in the inhibition of cell proliferation and cell cycle arrest selectively in G2/M phase.

Anticholesteremic Agents↗

PubMed2000

Selenium modulation of cell proliferation and cell cycle biomarkers in normal and premalignant cells of the rat mammary gland.

The present study was designed to assess the effect of Se-methylselenocysteine or triphenylselenonium chloride treatment on cell proliferation [bromodeoxyuridine (BrdUrd) labeling] and cell cycle biomarkers [proliferating cell nuclear antigen (PCNA), cyclin D1, and p27/Kip 1] in the intact mammary gland of rats. Immunohistochemical assays of the above end points were carried out in different morphological structures: (a) terminal end bud cells and alveolar cells of a maturing mammary gland undergoing active differentiation; and (b) premalignant mammary intraductal proliferations (IDPs) identified at 6 weeks after carcinogen dosing. Neither compound was found to affect BrdUrd labeling or the expression of cell cycle biomarkers in the normal terminal-end bud cells and alveolar cells. Se-methylselenocysteine reduced the total number of IDP lesions by approximately 60%. Interestingly, this was not accompanied by decreases in BrdUrd labeling or the proportion of IDP cells expressing PCNA and cyclin D1. An enhancement in the fraction of p27/Kip 1-positive IDP cells, however, was detected as a result of Se-methylselenocysteine treatment. Although triphenylselenonium chloride did not reduce the total number of IDPs, there were more of the smaller-sized lesions and fewer of the larger-sized lesions compared with those found in the control group. Triphenylselenonium chloride also significantly decreased the proportion of IDP cells incorporating the BrdUrd label or expressing PCNA and cyclin D1. The above findings suggest that early transformed cells are sensitive to selenium intervention, whereas normal proliferating cells are not. It is possible that Se-methylselenocysteine blocks carcinogenesis by a pathway that may not involve cell growth inhibition as a primary response; in contrast, triphenylselenonium chloride is likely to act by a cytostatic mechanism. The data also imply that selenium efficacy testing in intervention trials is possible with the use of biomarkers, provided that the appropriate biomarkers are matched with the selenium compound of interest and that the pathological characteristics of the cell population to be evaluated are taken into consideration.

Animals↗

PubMed2006

Nicotine as a mitogenic stimulus for pancreatic acinar cell proliferation.

Cell proliferation is an important process in life for growth of normal and cancer cells. The signal transduction pathways activated during this process are strictly regulated. This editorial focuses on the role of nicotine, a mitogen, in the induction of signaling pathways resulting in proliferation of pancreatic tumor cells and compares these events with those in normal acinar cells isolated from the rat pancreas. The data shows striking similarities between these two cellular systems. In addition, the editorial reviews very recent literature of the contribution of MAPK signaling in cell lines associated with human diseases. A prospective cellular model of nicotine induced activation of MAPK cascade is presented.

Animals↗

PubMed2000

Protein kinase C regulation of corneal endothelial cell proliferation and cell cycle.

PURPOSE: The purpose of this study was to determine the role of protein kinase C (PKC) in corneal endothelial cell proliferation. METHODS: Immunocytochemistry and Western blotting were used to define the PKC isoforms expressed in primary cultures of rat corneal endothelial cells. For proliferation studies, primary cultures of rat corneal endothelial cells were serum-starved for 48 hours and incubated for 2 hours with the PKC inhibitors staurosporine (10(-9) to 10(-7) M), chelerythrine (10(-9) to 5 x 10(-8) M), or calphostin C (10(-9) to 10(-7) M). Individual PKC isoforms were inhibited using PKCalpha antisense oligonucleotide transfection or exposure for 1 hour to myristoylated, pseudosubstrate-derived peptide inhibitors against PKCalpha, -alphassgamma, -epsilon, and -delta (10(-8) to 10(-6) M). Cells were then stimulated with 2.5% serum for 24 hours. Cell proliferation was measured with bromodeoxyuridine (BrDU) and Ki67 immunocytochemistry. Protein level of cyclin E was determined by Western blotting. RESULTS: PKCalpha, -ssII, -delta, -epsilon, -iota, -eta, -gamma, and -theta were detected in corneal endothelial cells. Maximum inhibition of PKC with staurosporine, calphostin C, and chelerythrine reduced cell proliferation to 7%, 31%, and 48% of control, respectively. Myristoylated peptide inhibition of PKCalpha and -epsilon reduced cell proliferation to 57% and 59% of control, respectively. PKCalpha antisense oligonucleotide reduced cell proliferation to 35% of control. Cyclin E protein level was decreased to 70%, 38%, 57%, and 43% of control in cells treated with calphostin C, staurosporine, chelerythrine, and PKCalpha antisense, respectively. CONCLUSIONS: PKC activity, in particular PKCalpha and -epsilon activity, is important in promoting corneal endothelial cell proliferation. Inhibition of PKC activity prohibits G1/S-phase progression and reduces cyclin E protein levels.

Animals↗

PubMed2003

Adipogenesis: a cross-talk between cell proliferation and cell differentiation.

The transition between cell proliferation and cell differentiation taking place during adipocyte differentiation is a tightly regulated process where both cell cycle regulators and differentiating factors interact, creating a cascade of events leading to the commitment of the cells into the adipocyte phenotype. Based on in-vitro cell models of adipocyte differentiation, the different stages of adipogenesis have been established, each of them with a particular pattern of gene expression. Re-entry into the cell cycle of growth-arrested preadipocytes is known as the clonal expansion phase. Growth-arrested preadipocytes undergo several rounds of cell cycle before terminally differentiating into adipocytes, suggesting that a cross-talk might exist between the cell cycle or the cell proliferation machinery and the factors controlling cell differentiation. I will focus this review on the influence of the proliferative phase of preadipocytes in the adipocyte differentiation process.

Adipocytes↗