Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.27 (AMPK)
 6,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression and function of a receptor tyrosine kinase, c-kit, in the adult bone marrow of the mouse were investigated by using monoclonal antibodies (mAbs) against the extracellular domain of murine c-kit. In adult C57BL/6 mouse, 7.8% of total bone marrow cells express c-kit on their surface. Half of the c-kit+ cells do not express lineage markers including Mac-1, Gr-1, TER-119, and B220, while the remainder coexpress myeloid lineage markers such as Mac-1 and Gr-1. After c-kit+ cells were removed from the bone marrow cell preparation, hemopoietic progenitor cells reactive to IL-3, GM-CSF, or M-CSF and also those which give rise to spleen colonies in irradiated recipients disappeared almost completely. Thus, most hemopoietic progenitors in the adult bone marrow express c-kit. To investigate whether or not c-kit has any role in the hemopoiesis of adult bone marrow, we took the advantage of one of the anti-c-kit mAbs that can antagonize the function of c-kit. As early as two days after the injection of 1 milligram of an antagonistic antibody, ACK2, almost all hemopoietic progenitor cells disappeared from the bone marrow, which eventually resulted in the absence of mature myeloid and erythroid cells in the bone marrow. These results provide direct evidence that c-kit is an essential molecule for constitutive intramarrow hemopoiesis, especially for the self-renewal of hemopoietic progenitor cells at various stages of differentiation.
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PMID:Expression and function of c-kit in hemopoietic progenitor cells. 171 68

The c-kit receptor tyrosine kinase is highly expressed by about 10% of the neurons in the dorsal root ganglia (DRGs) of mouse embryos. We investigated the in vitro effect of stem cell factor (SCF), the ligand for c-kit receptor, on DRGs. Recombinant murine SCF (rmSCF) induced the outgrowth of c-kit-positive neurites from DRGs of normal (+/+) embryos. The effect of SCF was dose dependent and completely abolished by anti-c-kit ACK2 monoclonal antibody (mAb). Some neurites whose outgrowth was induced by nerve growth factor (NGF) were c-kit-positive, but anti-NGF mAb did not inhibit the rmSCF-induced neurite outgrowth. rmSCF did not induce neurite outgrowth from DRGs of W/W embryos that did not express c-kit receptors on the cell surface and of W42/W42 mutant embryos that expressed c-kit receptors without tyrosine kinase activity. rmSCF also had a trophic effect on c-kit-positive neurons in the culture of dissociated DRG cells. Most c-kit-positive neurons appeared to respond to NGF as well, and the SCF-responsive subpopulation represented about 10% of NGF-responsive neurons. rmSCF did not support the survival of DRG neurons from embryos of W/W and W42/W42 genotypes. These results suggest that the stimulus through the c-kit receptor tyrosine kinase has an important role in development of the peripheral nervous system.
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PMID:Stem cell factor induces outgrowth of c-kit-positive neurites and supports the survival of c-kit-positive neurons in dorsal root ganglia of mouse embryos. 750 40

In vivo injection of a neutralizing, monoclonal antibody (ACK2) to the receptor tyrosine kinase (c-kit) disrupts the normal motility patterns of the mouse small intestine. Immunohistochemical studies showed that cells expressing c-kit-like immunoreactivity (c-kit-LI) decreased in numbers in response to ACK2, but the identity of these cells is unknown. We investigated the identity and development of the cells that express c-kit-LI in the mouse small intestine and colon. Cells in the region of the myenteric plexus and deep muscular plexus of the small intestine and in the subserosa, in the myenteric plexus region, within the circular and longitudinal muscle layers, and along the submucosal surface of the circular muscle in the colon were labeled with ACK2. The distribution of cells that express c-kit-LI was the same as that of interstitial cells (ICs). In whole-mount preparations cells with c-kit-LI were interconnected, forming a network similar to the network formed by cells that stained with methylene blue, which has been used as a marker for ICs in the mouse gastrointestinal tract. Immunocytochemistry verified that ICs were labeled with ACK2. Multiple injections of animals with ACK2 between days 0 and 8 post partum (pp) caused a dramatic reduction in the number of ICs compared to control animals. From an ultrastructural point of view, the proliferation and development appeared to be suppressed in some classes of ICs, while others displayed an altered course of development. Functional studies showed that the decrease in ICs was accompanied by a loss of electrical rhythmicity in the small intestine and reduced neural responses in the small bowel and colon. Morphological experiments showed that c-kit-positive cells are ICs, and physiological evidence reinforced the concept that ICs are involved in generation of rhythmicity and translation of neural inputs in gastrointestinal smooth muscles. Controlling the development of ICs provides a powerful new tool for the investigation of the physiological role of these cells.
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PMID:c-kit-dependent development of interstitial cells and electrical activity in the murine gastrointestinal tract. 753 51

Studies of mice containing mutations in the genes for a receptor tyrosine kinase, c-kit, or its cognate ligand, Steel factor (SLF), establish that this signaling pathway is required for the development of melanocytes from their precursors in the embryonic neural crest (NC). In order to define the mechanism of this requirement, we have labeled cells expressing c-kit with an anti-c-kit antibody (ACK2) and studied the action of SLF on these cells in cultures of murine trunk NC. c-kit positive (c-kit+) cells first appeared after 2 days in culture and were morphologically indistinguishable from other NC cells. These cells subsequently expressed tyrosinase-related protein, an early marker for the melanocyte lineage, and became pigmented in the presence of a phorbol ester. Further, elimination of the c-kit+ population, by incubating the cultures in ACK2, resulted in the ablation of the melanocyte population, but had no effect on the generation of other neural crest derivatives. These data indicate that c-kit+ cells arising from the neural crest are melanocyte progenitors. The addition of SLF to these cultures stimulated an increase in the number of c-kit+ cells, and further studies indicated that SLF acts as both a survival and a proliferative factor for c-kit+ cells. These findings provide a mechanism of regulation of melanocyte development, whereby c-kit is exclusively expressed by melanocyte progenitors within the neural crest precursor population, and subsequent survival and proliferation of these progenitors is regulated by SLF.
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PMID:Steel factor directs melanocyte development in vitro through selective regulation of the number of c-kit+ progenitors. 754 Jan 55

We examined developmental changes in responses of the isolated segment of the ileum of BALB/c mice treated with a monoclonal antibody (ACK2) to the receptor tyrosine kinase (Kit) for 4 days postnatally to pharmacological agents in vitro. Rhythmic contraction and relaxation of the isolated ileum started to appear on day 4 postpartum, and the sensitivity to acetylcholine (ACh) decreased gradually after birth. Treatment with ACK2 induced augmentation of contractile responses and receptor sensitivity of the longitudinal muscle of the ileum to ACh, bradykinin, and prostaglandin F2 alpha. ACh induced larger depolarization in smooth muscle cells of the ileum in the ACK2-treated mice than in the control. Circular muscle responses to these substances, as measured by changes in intraluminal pressure, were not altered by ACK2 treatment. Results suggest that interstitial cells play an important role not only in the development of the pacemaking system of the small intestine but also in the functional development of the contractile properties of the intestinal smooth muscle.
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PMID:Impairment of Kit-dependent development of interstitial cells alters contractile responses of murine intestinal tract. 894 89

Chronic injection of an anti-c-KIT receptor tyrosine kinase monoclonal antibody (ACK2) results in the disruption of the normal motility patterns of young BALB/c mice intestine. This effect is accompanied by a drastic decrease in the number of intestinal c-kit-expressing (c-kit+) cells when studied immunohistochemically with the fluorescence-labelled antibody. In order to clarify the mechanism underlying the ACK2 action and the physiological roles of intestinal c-kit+ cells, we studied the excitability of intestinal c-kit+ cells in primary culture by use of the nystatin perforated-patch-clamp technique. Under voltage-clamp at -40 mV, the majority of c-kit+ cells tested (59/70) elicited rhythmic current waves with an amplitude and frequency of 263 +/- 24 pA and 2.30 +/- 0.25 cycles/min (mean +/- SEM), respectively. Intracellular perfusion of the c-kit+ cells with ethylenebis (okonitrilo) tetraacetate (EGTA) as well as a nominally Ca(2+)-free external solution or low holding voltage (< -60 mV) prevented the rhythmic current. The reversal potential of the rhythmic current was close to the equilibrium potential for Cl-(ECl). Moreover the rhythmic current was depressed by a Cl- channel blocker, 4-acetoamido-4-isothiocyanat-ostilbene-2,2'-disulphoni c acid (SITS). The smooth muscle cells freshly dissociated from the same intestinal specimen revealed a Ca(2+)-activated K+ current, as has been described in a variety of smooth muscle cells. Cultured smooth muscle cells from the ileum preparation lacked neither the Ca(2+)-activated K+ nor rhythmic Cl- currents. Smooth muscle cells freshly dissociated from the same ileum preparation and those in culture showed no immunoreactivity with the labelled ACK2, which was consistent with our previous in situ study. Results provided direct evidence that the intestinal c-kit+ cells, but not the smooth muscle cells, possess a rhythmic Cl- current oscillation, suggesting their participation in pacemaker activity for the peristaltic gut movement.
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PMID:Rhythmic Cl- current and physiological roles of the intestinal c-kit-positive cells. 902 76

The c-kit receptor tyrosine kinase (KIT) is constitutively activated by naturally occurring mutations in either the juxtamembrane domain or the kinase domain. Although the juxtamembrane domain mutations led to ligand-independent KIT dimerization, the kinase domain mutations (Asp814 --> Val or Tyr) did not. In an effort to determine if the kinase domain mutant could transfer oncogenic signaling without receptor dimerization, we have constructed the truncated types of c-kitWild and c-kitTyr814 cDNAs (c-kitDel-Wild and c-kitDel-Tyr814 cDNAs, respectively), in which ligand-binding and ligand-induced dimerization domains were deleted. When c-kitDel-Wild and c-kitDel-Tyr814 genes were introduced into a murine interleukin-3 (IL-3)-dependent cell line Ba/F3, KITDel-Tyr814 was constitutively phosphorylated on tyrosine and activated, whereas KITDel-Wild was not. In addition, Ba/F3 cells expressing KITDel-Tyr814 (Ba/F3(Del-Tyr814)) grew in suspension culture without the addition of exogenous growth factor, whereas Ba/F3 cells expressing KITDel-Wild (Ba/F3(Del-Wild)) required IL-3 for growth. The factor-independent growth of Ba/F3(Del-Tyr814) cells was virtually abrogated by coexpression of KITW42 that is a dominant-negative form of KIT, but not by that of KITWild, suggesting that KITDel-Tyr814 may not function as a monomer but may require receptor dimerization for inducing factor-independent growth. Furthermore, KITDel-Tyr814 was found to be coimmunoprecipitated with KITWild or KITW42 by an ACK2 monoclonal antibody directed against the extracellular domain of KIT. Moreover, KITW42 was constitutively associated with a chimeric FMS/KITTyr814 receptor containing the ligand-binding and receptor dimerization domain of c-fms receptor (FMS) fused to the transmembrane and cytoplasmic domain of KITTyr814, but not with a chimeric FMS/KITWild receptor even after stimulation with FMS-ligand. These results suggest that constitutively activating mutation of c-kit at the Asp814 codon may cause a conformation change that leads to receptor self-association not in the extracellular domain and that the receptor self-association of the Asp814 mutant may be important for activation of downstream effectors that are required for factor-independent growth and tumorigenicity.
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PMID:Activating mutation in the catalytic domain of c-kit elicits hematopoietic transformation by receptor self-association not at the ligand-induced dimerization site. 994 75

1. The gastric corpus and antrum contain interstitial cells of Cajal (ICC) within the tunica muscularis. We tested the hypothesis that ICC are involved in the generation and regeneration of electrical slow waves. 2. Normal, postnatal development of slow wave activity was characterized in tissues freshly removed from animals between birth and day 50 (D50). Slow wave amplitude and frequency increased during this period. Networks of myenteric ICC (IC-MY) were present in gastric muscles at birth and did not change significantly in appearance during the period of study as imaged by confocal immunofluorescence microscopy. 3. IC-MY networks were maintained and electrical rhythmicity developed in organ culture in a manner similar to normal postnatal development. Electrical activity was maintained for at least 48 days in culture. 4. Addition of a neutralizing antibody (ACK2) for the receptor tyrosine kinase, Kit, to the culture media caused progressive loss of Kit-immunoreactive cells. Loss of Kit-immunoreactive cells was associated with loss of slow wave activity. Most muscles became electrically quiescent after 3-4 weeks of exposure to ACK2. 5. In some muscles small clusters of Kit-immunoreactive IC-MY remained after culturing with ACK2. These muscles displayed slow wave activity but only in the immediate regions in which Kit-positive IC-MY remained. These data suggest that regions without Kit-immunoreactive cells cannot generate or regenerate slow waves. 6. After loss of Kit-immunoreactive cells, the muscles could not be paced by direct electrical stimulation. Stimulation with acetylcholine also failed to elicit slow waves. The data suggest that the generation of slow waves is an exclusive property of IC-MY; smooth muscle cells may not express the ionic apparatus necessary for generation of these events. 7. We conclude that IC-MY are an essential element in the spontaneous rhythmic electrical and contractile activity of gastric muscles. This class of ICC appears to generate slow wave activity and may provide a means for regeneration of slow waves.
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PMID:Interstitial cells of cajal generate electrical slow waves in the murine stomach. 1037 7

Triple negative (TN) breast cancer is more frequent in women who are obese or have type II diabetes, as well as young women of color. These cancers do not express receptors for the steroid hormones estrogen or progesterone, or the type II receptor tyrosine kinase (RTK) Her-2 but do have upregulation of basal cytokeratins and the epidermal growth factor receptor (EGFR). These data suggest that aberrations of glucose and fatty acid metabolism, signaling through EGFR and genetic factors may promote the development of TN cancers. The anti-type II diabetes drug metformin has been associated with a decreased incidence of breast cancer, although the specific molecular subtypes that may be reduced by metformin have not been reported. Our data indicates that metformin has unique anti-TN breast cancer effects both in vitro and in vivo. It inhibits cell proliferation (with partial S phase arrest), colony formation and induces apoptosis via activation of the intrinsic and extrinsic signaling pathways only in TN breast cancer cell lines. At the molecular level, metformin increases P-AMPK, reduces P-EGFR, EGFR, P-MAPK, P-Src, cyclin D1 and cyclin E (but not cyclin A or B, p27 or p21), and induces PARP cleavage in a dose- and time-dependent manner. These data are in stark contrast to our previously published biological and molecular effects of metformin on luminal A and B, or Her-2 type breast cancer cells. Nude mice bearing tumor xenografts of the TN line MDA-MB-231, treated with metformin, show significant reductions in tumor growth (p = 0.0066) and cell proliferation (p = 0.0021) as compared to untreated controls. Metformin pre-treatment, before injection of MDA-MB-231 cells, results in a significant decrease in tumor outgrowth and incidence. Given the unique anti-cancer activity of metformin against TN disease, both in vitro and in vivo, it should be explored as a therapeutic agent against this aggressive form of breast cancer.
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PMID:Metformin induces unique biological and molecular responses in triple negative breast cancer cells. 1971 81

Disregulation of epidermal growth factor receptor (EGFR) signaling directly promotes bypass of proliferation and survival restraints in a high frequency of epithelia-derived cancer. As such, much effort is currently focused on decoding the molecular architecture supporting EGFR activation and function. Here, we have leveraged high throughput reverse phase protein lysate arrays, with a sensitive fluorescent nanocrystal-based phosphoprotein detection assay, together with large scale siRNA-mediated loss of function to execute a quantitative interrogation of all elements of the human kinome supporting EGF-dependent signaling. This screening platform has captured multiple novel contributions of diverse protein kinases to modulation of EGFR signal generation, signal amplitude, and signal duration. As examples, the prometastatic SNF1/AMPK-related kinase hormonally upregulated Neu kinase was found to support EGFR activation in response to ligand binding, whereas the enigmatic kinase MGC16169 selectively supports coupling of active EGFR to ERK1/2 regulation. Of note, the receptor tyrosine kinase MERTK and the pyrimidine kinase UCK1 were both found to be required for surface accumulation of EGFR and subsequent pathway activation in multiple cancer cell backgrounds and may represent new targets for therapeutic intervention.
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PMID:Comprehensive mapping of the human kinome to epidermal growth factor receptor signaling. 2042 2


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