Light is one of the most important factor influencing plant growth and development all through their life cycle. One of the well-known light-regulated processes is de-etiolation, i.e. the switch from skotomorphogenesis to photomorphogenesis. The hormones cytokinins (CKs) play an important role during the establishment of photomorphogenesis as exogenous CKs induced photomorphogenesis of dark-grown seedlings. Most of the studies are conducted on the plant model Arabidopsis, but no or few information are available for important crop species, such as tomato (Solanum lycopersicum L.). In our study, we analyzed for the first time the endogenous CKs content in tomato hypocotyls during skotomorphogenesis, photomorphogenesis and de-etiolation. For this purpose, two tomato genotypes were used: cv. Rutgers (wild-type; WT) and its corresponding mutant (7B-1) affected in its responses to blue light (BL). Using physiological and molecular approaches, we identified that the skotomorphogenesis is characterized by an endoreduplication-mediated cell expansion, which is inhibited upon BL exposure as seen by the accumulation of trancripts encoding CycD3, key regulators of the cell cycle. Our study showed for the first time that iP (isopentenyladenine) is the CK accumulated in the tomato hypocotyl upon BL exposure, suggesting its specific role in photomorphogenesis. This result was supported by physiological experiments and gene expression data. We propose a common model to explain the role and the relationship between CKs, namely iP, and endoreduplication during de-etiolation and photomorphogenesis.

• MeSH
• buněčný cyklus účinky léků   genetika   MeSH
• cyklin D3 genetika   metabolismus   MeSH
• cytokininy metabolismus   MeSH
• endoreduplikace fyziologie   účinky záření   MeSH
• fylogeneze MeSH
• hypokotyl fyziologie   účinky záření   MeSH
• isopentenyladenosin metabolismus   MeSH
• morfogeneze fyziologie   účinky záření   MeSH
• ploidie MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• semenáček fyziologie   účinky záření   MeSH
• Solanum lycopersicum fyziologie   účinky záření   MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• cyklin D3 * metabolismus   MeSH
• cyklin-dependentní kinasy * antagonisté a inhibitory   metabolismus   MeSH
• G1 fáze účinky léků   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• lymfom * enzymologie   patologie   terapie   MeSH
• molekulární modely MeSH
• nádorové buněčné linie MeSH
• proliferace buněk účinky léků   MeSH
• S fáze účinky léků   MeSH
• Check Tag
• lidé MeSH

OBJECTIVE: Cardiac hypertrophy is induced by a number of stimuli and can lead to cardiomyopathy and heart failure. Present knowledge suggests that cell-cycle regulatory proteins take part in hypertrophy. We have investigated if the D-type cyclins are involved in cardiac hypertrophy. METHODS: The expression and activity of the D-type cyclins and associated kinases in cardiomyocytes were studied during angiotensin II- and pressure overload-induced hypertrophy in rats (Rattus norvegicus) and in isolated, neonatal cardiomyocytes. Expression of the D-type cyclins was manipulated pharmacologically and genetically in neonatal myocytes. RESULTS: In the left ventricle, there was a low, constitutive expression of the D-type cyclins, which may have a biological role in normal, adult myocytes. The protein level and the associated kinase activity of the D-type cyclins were up-regulated during hypertrophic growth. The increase in cyclin D expression could be mimicked in vitro in neonatal cardiac myocytes. Interestingly, the cyclin Ds were up-regulated by hypertrophic elicitors that stimulate different signalling pathways, suggesting that cyclin D expression is an inherent part of cardiac hypertrophy. Treatment of myocytes with the compound differentiation inducing factor 1 inhibited expression of the D-type cyclins and impaired hypertrophic growth induced by angiotensin II, phenylephrine and serum. The response to hypertrophic elicitors could be restored in differentiation inducing factor 1-treated myocytes by expressing cyclin D2 from a heterologous promoter. CONCLUSION: Our results point to the D-type cyclins as important regulators of cardiac hypertrophy. This supports the notion that cell-cycle regulatory proteins regulate hypertrophic growth.

• MeSH
• angiotensin II MeSH
• cyklin D1 agonisté   analýza   metabolismus   MeSH
• cyklin D2 MeSH
• cyklin D3 MeSH
• cyklin-dependentní kinasy analýza   metabolismus   MeSH
• cykliny analýza   metabolismus   MeSH
• hypertrofie levé komory srdeční * metabolismus   MeSH
• kardiomyocyty metabolismus   účinky léků   MeSH
• krysa rodu rattus MeSH
• kultivované buňky MeSH
• potkani Wistar MeSH
• proteiny Caenorhabditis elegans * MeSH
• proteiny červů farmakologie   MeSH
• signální transdukce * fyziologie   MeSH
• transportní proteiny farmakologie   MeSH
• western blotting metody   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

The stimulation of thyroid cell proliferation by TSH through cAMP depends on permissive comitogenic factors, generally the insulin-like growth factors and insulin. In dog thyroid primary cultures, the use of the phosphodiesterase-resistant analog of cAMP (Bu)(2)cAMP instead of TSH allowed to unveil a potent comitogenic activity of carbamylcholine, which can substitute for insulin and was shown to mimic insulin action on cell cycle regulatory proteins. Like insulin, carbamylcholine induced the accumulation of cyclin D3 and overcame the repression by cAMP of this protein, which was shown 1) to be essential for cell cycle progression by means of microinjections of a neutralizing antibody; and 2) to be rate limiting for the cAMP-dependent assembly of cyclin D3-cdk4 complexes, their nuclear translocation and the phosphorylation of pRb. Relative to insulin, carbamylcholine offers the significant experimental advantage that its signaling cascades can be immediately deactivated by the muscarinic antagonist atropine. In the presence of carbamylcholine, the elimination of (Bu)(2)cAMP blocked within 2 h the entry of cells into DNA synthesis phase, but the addition of atropine still permitted the entry of cells in S phase. These data support our view that the progression in G1 phase stimulated by cAMP consists of at least two essential actions that are clearly dissociated: in a first stage, depending on the supportive activity of an agent that stimulates the required cyclin D3 accumulation, cAMP induces the assembly and nuclear translocation of cyclin D3-cdk4 complexes, and then cAMP can exert alone the last crucial control that determines the cell commitment toward DNA replication.

• MeSH
• AMP cyklický * fyziologie   MeSH
• buněčné jádro metabolismus   MeSH
• buněčný cyklus fyziologie   účinky záření   MeSH
• cyklin D3 MeSH
• cyklin-dependentní kinasa 4 MeSH
• cyklin-dependentní kinasy fyziologie   MeSH
• cykliny fyziologie   MeSH
• dibutyryl cyklický AMP farmakologie   MeSH
• DNA biosyntéza   MeSH
• G1 fáze MeSH
• hypertrofie MeSH
• karbachol * farmakologie   metabolismus   MeSH
• kultivované buňky MeSH
• mitóza účinky léků   MeSH
• proteiny buněčného cyklu fyziologie   MeSH
• protoonkogenní proteiny * MeSH
• psi MeSH
• štítná žláza * cytologie   metabolismus   patologie   účinky léků   MeSH
• synergismus léků MeSH
• zvířata MeSH
• Check Tag
• psi MeSH
• zvířata MeSH

BACKGROUND & AIMS: The G1/S-phase controlling mechanism known as the RB pathway is commonly deregulated in human malignancies. Here, the abundance and localization of key components of the retinoblastoma (RB) pathway were determined in exophytic and flat colorectal adenomas. METHODS: Samples of normal colonic mucosa (n = 41) and flat (n = 45) and exophytic (n = 26) adenomas were examined immunohistochemically using antibodies to cyclins D1, D2, D3, cyclin-dependent kinase (CDK) 4, retinoblastoma protein (pRB), and the CDK inhibitors p16INK4a, p18INK4c, and p19INK4d. RESULTS: In normal colonic epithelium, cyclin D2 was undetectable; expression of cyclin D1, CDK4, and pRB correlated with proliferation; and p16, p18, p19, and cyclin D3 were most abundant in quiescent, differentiated cells. Adenomas showed elevated expression of cyclin D1 and pRB, frequent induction of cyclin D2, and absence of p16. No obvious abnormalities were found for p18, p19, or cyclin D3. Overexpressed cyclin D2 was more common among exophytic and pRB among flat adenomas, respectively. Elevated cyclin D1, D2, and CDK4 correlated with enhanced dysplasia. CONCLUSIONS: Aberrant expression of cyclins D1, D2, CDK4, p16, and pRB occur in significant subsets of exophytic and flat adenomas, particularly among cases with high-grade dysplasia. Such defects of the RB pathway may perturb cell-cycle control and thereby contribute an early step in colorectal tumorigenesis.

• MeSH
• adenom * metabolismus   patologie   MeSH
• cyklin D1 analýza   MeSH
• cyklin D2 MeSH
• cyklin D3 MeSH
• cyklin-dependentní kinasa 4 MeSH
• cyklin-dependentní kinasy analýza   MeSH
• cykliny analýza   MeSH
• dospělí MeSH
• G1 fáze * MeSH
• inhibitor p16 cyklin-dependentní kinasy analýza   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádory tračníku * metabolismus   patologie   MeSH
• protoonkogenní proteiny * MeSH
• retinoblastomový protein analýza   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH

Dog thyroid epithelial cells in primary culture constitute a physiologically relevant model of positive control of DNA synthesis initiation and G0-S prereplicative phase progression by cAMP as a second messenger for thyrotropin (thyroid-stimulating hormone [TSH]). As previously shown in this system, the cAMP-dependent mitogenic pathway differs from growth factor cascades as it stimulates the accumulation of p27(kip1) but not cyclins D. Nevertheless, TSH induces the nuclear translocations and assembly of cyclin D3 and cdk4, which are essential in cAMP-dependent mitogenesis. Here we demonstrate that transforming growth factor beta(1) (TGFbeta(1)) selectively inhibits the cAMP-dependent cell cycle in mid-G1 and various cell cycle regulatory events, but it weakly affects the stimulation of DNA synthesis by epidermal growth factor (EGF), hepatocyte growth factor, serum, and phorbol esters. EGF+serum and TSH did not interfere importantly with TGFbeta receptor signaling, because they did not affect the TGFbeta-induced nuclear translocation of Smad 2 and 3. TGFbeta inhibited the phosphorylation of Rb, p107, and p130 induced by TSH, but it weakly affected the phosphorylation state of Rb-related proteins in EGF+serum-treated cells. TGFbeta did not inhibit c-myc expression. In TSH-stimulated cells, TGFbeta did not affect the expression of cyclin D3, cdk4, and p27(kip1), nor the induced formation of cyclin D3-cdk4 complexes, but it prevented the TSH-induced relocalization of p27(kip1) from cdk2 to cyclin D3-cdk4. It prevented the nuclear translocations of cdk4 and cyclin D3 without altering the assembly of cyclin D3-cdk4 complexes probably formed in the cytoplasm, where they were prevented from sequestering nuclear p27(kip1) away from cdk2. This study dissociates the assembly of cyclin D3-cdk4 complexes from their nuclear localization and association with p27(kip1). It provides a new mechanism of regulation of proliferation by TGFbeta, which points out the subcellular location of cyclin D-cdk4 complexes as a crucial factor integrating mitogenic and antimitogenic regulations in an epithelial cell in primary culture.

• MeSH
• AMP cyklický * fyziologie   MeSH
• biologický transport MeSH
• buněčné dělení MeSH
• buněčný cyklus fyziologie   MeSH
• cyklin D3 MeSH
• cyklin-dependentní kinasa 2 MeSH
• cyklin-dependentní kinasa 4 MeSH
• cyklin-dependentní kinasy * metabolismus   MeSH
• cykliny * metabolismus   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• epitelové buňky cytologie   MeSH
• exprese genu MeSH
• fosforylace MeSH
• inhibitor p27 cyklin-dependentní kinasy MeSH
• kinasy CDC2-CDC28 * MeSH
• kultivované buňky MeSH
• mitogeny farmakologie   MeSH
• nádorové supresorové proteiny * MeSH
• protein Smad2 MeSH
• protein Smad3 MeSH
• protein-serin-threoninkinasy MeSH
• proteiny asociované s mikrotubuly * metabolismus   MeSH
• proteiny buněčného cyklu * MeSH
• protoonkogenní proteiny c-myc biosyntéza   MeSH
• protoonkogenní proteiny * MeSH
• psi MeSH
• retinoblastomový protein metabolismus   MeSH
• štítná žláza cytologie   MeSH
• thyreotropin metabolismus   MeSH
• trans-aktivátory metabolismus   MeSH
• transformující růstový faktor beta * fyziologie   MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• psi MeSH
• zvířata MeSH

The proliferation of most normal cells depends on the synergistic interaction of several growth factors and hormones, but the cell cycle basis for this combined requirement remains largely uncharacterized. We have addressed the question of the requirement for insulin/IGF-1 also observed in many cell culture systems in the physiologically relevant system of primary cultures of dog thyroid epithelial cells stimulated by TSH, which exerts its mitogenic activity only via cAMP. The induction of cyclin A and cdc2, the phosphorylation of cdk2, the nuclear translocation of cdk4 and the assembly of cyclin D3-cdk4 complexes required the synergy of TSH and insulin. Cyclin D3 (the most abundant cyclin D) was necessary for the proliferation stimulated by TSH in the presence of insulin as shown by microinjection of a neutralizing antibody. Cyclin D3 accumulation and activity were differentially regulated by insulin and TSH, which points out this cyclin as an integrator that ranks these comitogenic pathways as supportive and activatory, respectively. Paradoxically TSH alone strongly repressed cyclin D3 accumulation. This inhibition was overridden by insulin, which markedly stimulated cyclin D3 mRNA and protein accumulation, but failed to assemble cyclin D3-cdk4 complexes in the absence of TSH. TSH unmasked the DCS-22 epitope of cyclin D3 and assembled cyclin D3-cdk4 in the presence of insulin. These data demonstrate that cyclin D synthesis and cyclin D-cdk assembly can be dissociated and complementarily regulated by different agents and signalling pathways.

• MeSH
• buněčný cyklus * MeSH
• cyklin D3 MeSH
• cykliny metabolismus   MeSH
• hypoglykemika farmakologie   MeSH
• inzulin metabolismus   farmakologie   MeSH
• kultivované buňky MeSH
• myši MeSH
• psi MeSH
• signální transdukce * účinky léků   MeSH
• štítná žláza metabolismus   patologie   MeSH
• synergismus léků MeSH
• thyreotropin metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

D-type cyclins are proto-oncogenic components of the 'RB pathway', a G1/S regulatory mechanism centred around the retinoblastoma tumour suppressor (pRB) implicated in key cellular decisions that control cell proliferation, cell-cycle arrest, quiescence, and differentiation. This study focused on immunohistochemical and immunochemical analysis of human adult testis and 32 testicular tumours to examine the differential expression and abundance of cyclins D1, D2, and D3 in relation to cell type, proliferation, differentiation, and malignancy. In normal testis, the cell type-restricted expression patterns were dominated by high levels of cyclin D3 in quiescent Leydig cells and the lack of any D-type cyclin in the germ cells, the latter possibly representing the only example of normal mammalian cells proliferating in the absence of these cyclins. Most carcinoma-in-situ lesions appeared to gain expression of cyclin D2 but not D1 or D3, while the invasive testicular tumours showed variable positivity for cyclins D2 and D3, but rarely D1. An unexpected correlation with differentiation rather than proliferation was found particularly for cyclin D3 in teratomas, a conceptually significant observation confirmed by massive up-regulation of cyclin D3 in the human teratocarcinoma cell line NTera2/D1 induced to differentiate along the neuronal lineage. These results suggest a possible involvement of cyclin D2 in the early stages of testicular oncogenesis and the striking examples of proliferation-independent expression point to potential dual or multiple roles of the D-type cyclins, particularly of cyclin D3. These findings extend current concepts of the biology of the cyclin D subfamily, as well as of the biology and oncopathology of the human adult testis. Apart from practical implications for the assessment of proliferation and oncogenic aberrations in human tissues and tumours, this study may inspire further research into the emerging role of the cyclin D proteins in the establishment and/or maintenance of the differentiated phenotypes.

• MeSH
• buněčná diferenciace MeSH
• buněčné dělení MeSH
• cyklin D1 analýza   MeSH
• cyklin D2 MeSH
• cyklin D3 MeSH
• cykliny analýza   MeSH
• dospělí MeSH
• imunoenzymatické techniky MeSH
• karcinom in situ chemie   MeSH
• lidé MeSH
• nádorové buňky kultivované MeSH
• nádorové proteiny analýza   MeSH
• testikulární nádory chemie   patologie   MeSH
• testis chemie   cytologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

In different systems, cyclic adenosine monophosphate (cAMP) either blocks or promotes cell cycle progression in mid to late G1 phase. Dog thyroid epithelial cells in primary culture constitute a model of positive control of DNA synthesis initiation and G0-S prereplicative phase progression by cAMP as a second messenger for thyrotropin (TSH). The cAMP-dependent mitogenic pathway is unique as it is independent of mitogen-activated protein kinase activation and differs from growth factor-dependent pathways at the level of the expression of several protooncogenes/transcription factors. This study examined the involvement of D-type G1 cyclins and their associated cyclin-dependent kinase (cdk4) in the cAMP-dependent G1 phase progression of dog thyroid cells. Unlike epidermal growth factor (EGF)+serum and other cAMP-independent mitogens, TSH did not induce the accumulation of cyclins D1 and D2 and partially inhibited the basal expression of the most abundant cyclin D3. However, TSH stimulation enhanced the nuclear detection of cyclin D3. This effect correlated with G1 and S phase progression. It was found to reflect both the unmasking of an epitope of cyclin D3 close to its domain of interaction with cdk4, and the nuclear translocation of cyclin D3. TSH and EGF+serum also induced a previously undescribed nuclear translocation of cdk4, the assembly of precipitable cyclin D3-cdk4 complexes, and the Rb kinase activity of these complexes. Previously, cdk4 activity was found to be required in the cAMP-dependent mitogenic pathway of dog thyrocytes, as in growth factor pathways. Here, microinjections of a cyclin D3 antibody showed that cyclin D3 is essential in the TSH/ cAMP-dependent mitogenesis, but not in the pathway of growth factors that induce cyclins D1 and D2. The present study (a) provides the first example in a normal cell of a stimulation of G1 phase progression occurring independently of an enhanced accumulation of cyclins D, (b) identifies the activation of cyclin D3 and cdk4 through their enhanced assembly and/or nuclear translocation, as first convergence steps of the parallel cAMP-dependent and growth factor mitogenic pathways, and (c) strongly suggests that this new mechanism is essential in the cAMP-dependent mitogenesis, which provides the first direct demonstration of the requirement for cyclin D3 in a G1 phase progression.

• MeSH
• AMP cyklický metabolismus   MeSH
• buněčné dělení účinky léků   fyziologie   MeSH
• buněčné jádro metabolismus   MeSH
• cyklin D3 MeSH
• cyklin-dependentní kinasa 4 MeSH
• cyklin-dependentní kinasy biosyntéza   metabolismus   MeSH
• cykliny metabolismus   MeSH
• epidermální růstový faktor farmakologie   MeSH
• epitopy analýza   MeSH
• fluorescenční protilátková technika MeSH
• G1 fáze fyziologie   MeSH
• hypoglykemika farmakologie   MeSH
• inzulin farmakologie   MeSH
• krevní proteiny farmakologie   MeSH
• kultivované buňky MeSH
• mitogeny farmakologie   MeSH
• protoonkogenní proteiny * MeSH
• psi MeSH
• štítná žláza cytologie   enzymologie   MeSH
• thyreotropin farmakologie   MeSH
• zvířata MeSH
• Check Tag
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The mammalian D-type cyclins D1, D2, and D3 activate the cyclin-dependent kinases CDK4 and CDK6 in G1 and thereby promote the cell's commitment to enter S phase. To elucidate the extent of functional overlap among the D-type cyclins, we have examined several aspects of the least characterized member of this subfamily of G cyclin proteins, cyclin D3. Microinjection of cyclin D3-neutralizing antibody inhibited G1/S transition in human (IMR-90) and rat (R12) diploid fibroblasts, indicating that analogous to cyclins D1 and D2, cyclin D3 is essential for timely progression through G1. In contrast to cyclins D1 and D2, cyclin D3 was (i) ubiquitously expressed among a panel of 70 human cultured cell types; (ii) strongly upregulated upon induction of HL-60 leukaemia cells to differentiate; and (iii) accumulated to high levels in a wide range of quiescent cell types in mouse and human differentiated tissues. Complementary analyses of human biopsies and mouse tissues at different stages of foetal and postnatal development revealed lineage-dependent transient or long-term accumulation of the cyclin D3 protein, correlating with initiation/establishment or maintenance of the mature phenotypes, respectively. Our data support the notion that the biological roles of the individual D-type cyclins are not fully redundant, and suggest a possible dual role for cyclin D3 in cell proliferation and induction and/or maintenance of terminal differentiation.

• MeSH
• akutní promyelocytární leukemie patologie   MeSH
• buněčná diferenciace fyziologie   MeSH
• buněčné dělení fyziologie   MeSH
• buněčné linie MeSH
• cyklin D3 MeSH
• cykliny biosyntéza   imunologie   fyziologie   MeSH
• G1 fáze fyziologie   MeSH
• HL-60 buňky MeSH
• interfáze fyziologie   MeSH
• kosterní svaly cytologie   metabolismus   MeSH
• lidé MeSH
• monoklonální protilátky chemie   MeSH
• nádorové buňky kultivované MeSH
• orgánová specificita MeSH
• S fáze fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH