Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.2 (focal adhesion kinase)
 44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have characterized the transduction pathways induced by leptin in the placenta, using human BeWo cells that express endogenous leptin receptors and synthesize leptin in a regulated manner. We first examined if the JAK-STAT phosphorylation cascade was functional in these cells. Phosphorylated JAK2 was primarily bound to a short 106kDa leptin receptor isoform and to a lesser extent to a 210kDa molecule. Leptin neither enhanced JAK2 phosphorylation nor activated STAT3 and STAT1 proteins indicating that JAK2 is constitutively activated and that the JAK-STAT transduction pathway is not recruited by leptin in BeWo cells. By contrast, leptin stimulated the transcription of the c-fos gene (3-fold) and cell proliferation (2-fold) as measured by DNA synthesis. Both effects were dependent on the rapid phosphorylation of p42-44 MAPK but not p38 MAPK. We conclude that a functional JAK-STAT pathway is not required for leptin to transduce proliferative signals in human placental cells. These findings extend the physiological action of leptin beyond its central effects, to the control of placental gene transcription and cell proliferation.
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PMID:Transduction of leptin growth signals in placental cells is independent of JAK-STAT activation. 1265 12

1. The human orphan G-protein coupled receptor bombesin receptor subtype 3 (hBRS-3) was screened for peptide ligands by a Ca(2+)mobilization assay resulting in the purification and identification of two specific ligands, the naturally occurring VV-hemorphin-7 (VV-H-7) and LVV-hemorphin-7 (LVV-H-7), from human placental tissue. These peptides were functionally characterized as full agonists with unique specificity albeit low affinity for hBRS-3 compared to other bombesin receptors. 2. VV-H-7 and LVV-H-7 induced a dose-dependent response in hBRS-3 overexpressing CHO cells, as well as in NCI-N417 cells expressing the hBRS-3 endogenously. The affinity of VV-H-7 was higher in NCI-N417 cells compared to overexpressing CHO cells. In detail, the EC(50) values were 45+/-15 microM for VV-H-7 and 183+/-60 microM for LVV-H-7 in CHO cells, and 19+/-6 microM for VV-H-7 and 38+/-18 microM for LVV-H-7 in NCI-N417 cells. Other hemorphins had no effect. Gastrin-releasing peptide (GRP) and neuromedin B (NMB) showed similar EC(50) values of 13-20 microM (GRP) and of 1-2 microM (NMB) on both cell lines. 3. Structure-function analysis revealed that both the N-terminal valine and the C-terminal phenylalanine residues of VV-H-7 are critical for the ligand-receptor interaction. 4. Endogenous hBRS-3 in NCI-N417 activated by VV-H-7 couples to phospholipase C resulting in changes of intracellular calcium, which is initially released from an inositol trisphosphate (IP(3))-sensitive store followed by a capacitive calcium entry from extracellular space. 5. VV-H-7-induced hBRS-3 activation led to phosphorylation of p42/p44-MAP kinase in NCI-N417 cells, but did not stimulate cell proliferation. In contrast, phosphorylation of focal adhesion kinase (p125(FAK)) was not observed.
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PMID:Identification and functional characterization of hemorphins VV-H-7 and LVV-H-7 as low-affinity agonists for the orphan bombesin receptor subtype 3. 1272 Oct 98

GLP-1, incretin with insulin-independent antidiabetic properties, is insulinomimetic upon glucose metabolism in extrapancreatic tissues, acting through specific receptors not associated to adenylate cyclase activation. We investigated the role of enzymes mediating insulin actions, in the GLP-1-induced glycogen synthase a activation in rat hepatocytes. GLP-1, like insulin, activates PI3K/PKB, p70s6k, p44 and p42 MAP-kinase. Wortmannin (PI3K/PKB inhibitor) blocked the stimulatory action of insulin on glycogen synthase a and reduced that of GLP-1; rapamycin (p70s6k inhibitor) was ineffective and PD98059 (MEK/MAPK inhibitor) decreased only the insulin effect; okadaic acid (PP-2A inhibitor) was ineffective, while TNFalpha (PP-1 inhibitor) blocked the action of insulin and reduced that of GLP-1; H-7 or Ro 31-8220 (PKC inhibitors) decreased the GLP-1 effect, while only H-7 reduced that of insulin. The activation of PI3K/PKB, PKC and PP-1, but not PP-2A, seems to mediate the GLP-1 stimulatory action on glycogen synthase a in rat hepatocytes, while MAPKs and p70s6k could participate in other GLP-1 effects.
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PMID:Cell signalling of the GLP-1 action in rat liver. 1285 Feb 80

During tumor metastasis, a fine-tuned balance between the formation and loosening of adhesive cell contacts has to occur, a process based on the regulated expression of integrins. Human ovarian OV-MZ-6 cancer cells express the integrin alpha(v)beta3, which associates with vitronectin (VN) and correlates with ovarian cancer progression. Adhesion and spreading of OV-MZ-6 cells on VN was accompanied by the formation of focal adhesion contacts and the recruitment of activated tyrosine-phosphorylated focal adhesion kinase. Cultivation of OV-MZ-6 cells on VN resulted in a significantly induced cell proliferation. This VN effect could be mimicked by cultivating cells on the immobilized alpha(v)beta3 directed peptide cyclo-Arg-Gly-Asp-D-Phe-Val (cRGDfV). VN-dependent OV-MZ-6 cell adhesion and proliferation was significantly enhanced by overexpression of alpha(v)beta3 and was accompanied by rapid and transient tyrosine-phosphorylation of p44(erk-1)/p42(erk-2) mitogen-activated protein kinase. Moreover, overexpression of alpha(v)beta3 and OV-MZ-6 cell attachment to VN increased cell motility up to 5-fold accompanied by prominent changes in cytoskeletal organization and cell morphology. Upon alpha(v)beta3/VN interaction, by cDNA expression microarray analysis we identified altered mRNA levels of c-myc, epidermal growth factor receptor (EGF-R), transcription factor Fra-1, prothymosin-alpha (PTMA), integrin-linked kinase (ILK), and the cell adhesion molecule SQM-1, candidates which are possibly involved in changes of the adhesive, migratory, and proliferative phenotype of human ovarian cancer cells.
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PMID:Ovarian cancer cell proliferation and motility is induced by engagement of integrin alpha(v)beta3/Vitronectin interaction. 1295 24

Tumor necrosis factor (TNF) alpha-induced adipose-related protein (TIARP) has recently been cloned as a TNFalpha-stimulated protein expressed in adipocytes. Its expression is differentiation-dependent and potentially involved in mediating TNFalpha-induced insulin resistance. To further characterize regulation of TIARP gene expression, 3T3-L1 adipocytes were treated with key hormones modulating insulin sensitivity and influencing adipocyte metabolism, and TIARP gene expression was determined by quantitative real-time RT-PCR. Interestingly, TIARP mRNA expression was stimulated almost 9-fold after 500 ng/ml GH were added for 16 h whereas addition of 10 microM isoproterenol, 100 nM insulin and 100 nM dexamethasone for 16 h significantly decreased TIARP gene expression to between 35 and 50% of control levels. In contrast, angiotensin 2 (10 microM) and triiodothyronine (1 microM) did not have any effect. The stimulatory effect of GH was time- and dose-dependent with stimulation occurring as early as 1 h after effector addition and at concentrations as low as 5 ng/ml GH. Moreover, pharmacological inhibition of Janus kinase 2 and p42/44 mitogen-activated protein kinase reversed the stimulatory effect of GH, suggesting that both signaling molecules are involved in activation of TIARP gene expression by GH. Furthermore, an increase of TIARP mRNA could be completely reversed to control levels by withdrawal of GH for 24 h. Taken together, these results show that TIARP is not only responsive to TNFalpha but also to important other hormones influencing glucose homeostasis and adipocyte metabolism. Thus, this factor may play an integrative role in the pathogenesis of insulin resistance and its link to obesity.
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PMID:GH is a positive regulator of tumor necrosis factor alpha-induced adipose related protein in 3T3-L1 adipocytes. 1296 43

We have reported previously that reactivation of progesterone receptor (PR) expression in estrogen receptor (ER)- and PR-negative MDA-MB-231 breast cancer cells enabled progesterone to inhibit cell growth and invasiveness, and to induce remarkable focal adhesions. The present study addressed molecular mechanisms that mediate these anticancer effects of progesterone in the PR-transfected breast cancer cells ABC28. In response to progesterone treatment are the marked up-regulation of cyclin-dependent kinase inhibitor protein p21WAF1/CIP1 and decreased expression of cyclin A, cyclin B1, and cyclin D1 that are required for G1 progression and during cell mitosis. Progesterone also induced down-regulation of phosphorylated MAPK (p42/44 MAPK). Furthermore, this study also demonstrated that MEK inhibitor PD98059 that inhibits the phosphorylation of p42/44 MAPK also caused reduction of cyclin D1 level and inhibition of cell proliferation. These results suggest that inhibition of p42/44 MAPK pathway is part of the mechanisms mediating progesterone's growth-inhibitory effect. On the other hand, progesterone-induced focal adhesion is mediated by separate pathway. Whereas PD98059 exhibited no effects on cell adhesion, inhibitory antibody to beta1-integrin was able to reverse progesterone-induced focal adhesion and progesterone-induced increase in the phosphorylation of focal adhesion kinase. On the other hand, beta1-integrin antibody had no effect on progesterone-mediated growth inhibition and on progesterone-mediated expression of cyclins p21CIP1/WAF1 and phosphorylation of P42/P44 MAPK. In the context of complex functions of progesterone in breast cancer and reproductive organs, identification of distinct pathways offers new strategies for designing therapeutic agents to target the specific pathway so as to minimize the side effects.
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PMID:Distinct molecular pathways mediate progesterone-induced growth inhibition and focal adhesion. 1297 Jan 68

Several distinct receptor proteins for the second messengers Ins(1,3,4,5)P(4) and PtdIns(3,4,5)P(3) are already known, such as the brain-specific p42(IP4), which we have previously cloned from different species, and cytohesins. However, it is still unclear whether proteins interacting with phosphoinositide and inositolpolyphosphate second messengers are regulated differently in different tissues. Here, we investigated these native proteins for comparison also from rat lung cytosol and purified them by PtdIns(3,4,5)P(3) affinity chromatography. Proteins selectively binding Ins(1,3,4,5)P(4) with high affinity also showed high affinity and specificity towards PtdIns(3,4,5)P(3). In lung cytosol, two prominent protein bands were found in the eluate from a PtdIns(3,4,5)P(3) affinity column. We identified these proteins by mass spectrometry as the cytohesin family of Arf guanosine nucleotide exchange factors (cytohesin 1, ARNO, GRP-1) and as Bruton's tyrosine kinase. Western blot analysis indicated that p42(IP4) was present in lung only at very low concentrations. Applying the affinity purification scheme established for rat lung cytosol to cytosol from rat brain, however, yielded only p42(IP4). We identified cytohesins in rat brain by Western blotting and PCR, but cytohesins surprisingly did not bind to the PtdIns(3,4,5)P(3)-affinity column. Gel filtration experiments of brain cytosol revealed that brain cytohesins are bound to large molecular weight complexes (150 to more than 500 kDa). Thus, we hypothesize that this finding explains why brain cytohesins apparently do not bind the inositolphosphate ligand. In lung cytosol, on the other hand, cytohesins occur as dimers. Gel filtration also showed that p42(IP4) in brain cytosol occurs as a monomer. Thus, oligomerization (homomeric or heteromeric) of InsP(4)/PtdInsP(3) binding proteins can modulate their function in a tissue-dependent manner because it can modify their ability to interact with the ligands.
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PMID:Oligomerization controls in tissue-specific manner ligand binding of native, affinity-purified p42(IP4)/centaurin alpha1 and cytohesins-proteins with high affinity for the messengers D-inositol 1,3,4,5-tetrakisphosphate/phosphatidylinositol 3,4,5-trisphosphate. 1449 94

Various cellular signaling pathways, such as phosphatidylinositol 3-kinase, calcineurin, Janus kinase 2/signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinase (MAPK) have been suggested to play an important role in skeletal muscle growth. Old muscle, compared with young muscle, lacks the ability to completely regrow its muscle mass after an atrophy-induced stimulus. it is hypothesized that defects and/or delays in the activation of specific cell signaling pathways of aged soleus muscle limit the potential for growth. To test this, 42 male Fischer 344 x Brown Norway rats, 30 mo old, were hindlimb immobilized for 10 days, and their muscle samples were compared with muscle samples analyzed from 3- to 4-mo-old rats in a previous report (Childs TE, Spangenburg EE, Vyas DR, and Booth FW. Am J Physiol Cell Physiol: 285: C391-C398, 2003). After 10 days, the immobilization was removed and rats were allowed to ambulate for a series of days. Alterations in the activation or deactivation status of specific signaling pathways were determined by comparing the phosphorylation (phos) and total concentration of specific signaling proteins (pan) through Western blotting with the 10-day immobilization group. Various cell signals and their respective time groups of the old rats were shown to be significantly different compared with the 10-day immobilization group. For example, peak increases during recovery from the immobilization were observed at 1) the third recovery day for calcineurin B-pan and 2) the sixth recovery day for glycogen synthase kinase-3beta-phos, p70 S6 kinase (p70S6k) -phos and -pan, calcineurin A-pan, STAT3-phos and -pan, p44 MAPK-pan, and p42 MAPK-pan. In contrast, Akt-pan, c-Jun NH2-terminal kinase-phos, and p38 MAPK-phos were observed to decrease from 10-day immobilization values to control levels. Also, Aktphos was unchanged among all groups. In a follow-up experiment in which muscle samples from both the present study and a previous study (Childs TE, Spangenburg EE, Vyas DR, and Booth FW. Am J Physiol Cell Physiol: 285: C391-C398, 2003) were reanalyzed together, the recovery-induced increase in p70S6k-phos from immobilization-atrophy was significantly attenuated in soleus muscles of the old group.
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PMID:Responsiveness of cell signaling pathways during the failed 15-day regrowth of aged skeletal muscle. 1451 1

Pancreatic endocrine tumours (PETs) occur sporadically or are inherited as part of the multiple endocrine neoplasia type-1 syndrome. Little is known about the molecular events leading to these tumours. Cyclin D1, a key regulator of the G1/S transition of the cell cycle, is overexpressed in a variety of human cancers as well as certain endocrine tumours. We hypothesized that similar to other endocrine tumours, cyclin D1 is overexpressed in human sporadic PETs. Cyclin D1 protein overexpression was found in 20 of 31 PETs (65%) when compared with normal pancreatic tIssue. Furthermore, Northern blot analysis suggests that cyclin D1 up-regulation occurs at the post-transcriptional level in some PETs. Because the key cell growth signalling pathways p42/p44/ERK (extracellular signal-regulated kinase), p38/MAPK (mitogen-activated protein kinase), and Akt/PKB (protein kinase B) can regulate cyclin D1 protein expression in other cell types, pancreatic endocrine tumours were analysed with phospho-specific antibodies against the active forms of these proteins to elucidate a tIssue-specific regulatory mechanism of cyclin D1 in PETs. We found frequent activation of the p38/MAPK and Akt pathways, but down-regulation of the ERK pathway, in cyclin D1 overexpressing PETs. This study demonstrates that cyclin D1 overexpression is associated with human sporadic PET tumorigenesis, and suggests that this up-regulation may occur at the post-transcriptional level. These findings will direct future studies of PETs towards cell cycle dysregulation and the identification of key growth factor pathways involved in the formation of these tumours.
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PMID:Frequent overexpression of cyclin D1 in sporadic pancreatic endocrine tumours. 1452 67

GnRH agonist therapy is known to reduce uterine leiomyoma volume, although the molecular mechanisms responsible for this effect remain poorly understood. In this study, we have investigated the molecular mechanisms involved in the anti-proliferative effect of a GnRH agonist, leuprolide acetate (LA), in uterine leiomyomas obtained from six patients treated with LA for 3 months before surgery (group B), compared with tumours from six untreated patients (group A). To this end, we have evaluated the expression and the activity of molecules involved in the regulation of cell survival and proliferation. In group B, the total activity of PI3K was reduced by 60% compared with control samples. Furthermore, LA caused a reduction of PKB activation of approximately 50%, measured as serine 473 phosphorylation. In parallel with PKB reduction in LA samples, we observed a 60% reduction in the phosphorylation of its substrate BAD. While Bcl-xL/BAD association was not significantly modified in LA-treated leiomyomas, BAD/14.3.3 interaction was reduced, due to a 50% decreased 14.3.3 expression. In addition, LA was able to reduce the expression of the antiapoptotic proteins FLIP and PED/PEA15 by 70 and 50% respectively, compared with control samples. We next evaluated the activation of MAP kinases in leiomyomas. Activation of p42 and p44 MAP kinase isoforms was increased by 30% in group B. However, the phosphorylation of the transcription factor Elk1 was not increased in a similar fashion in LA-treated leiomyomas compared with group A. Thus, these data suggest that LA reduction of leiomyoma volume is mediated at least in part by a decreased activation of the PI3K/PKB survival pathway and by the suppression of antiapoptotic factors.
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PMID:Molecular mechanisms involved in GnRH analogue-related apoptosis for uterine leiomyomas. 1466 5


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