Polyamines negatively regulate posttranscription of the P53 gene in small intestinal crypt cells

1998 ◽  
Vol 114 ◽  
pp. A431
Author(s):  
J.-Y. Wang ◽  
J. Li ◽  
AR. Patel ◽  
L. Li ◽  
JN. Rao
Keyword(s):  
P53 Gene ◽  
Intestinal Crypt ◽  
Small Intestinal ◽  
Crypt Cells

scholarly journals A novel marker glycoprotein for the microvillus membrane of surface colonocytes of rat large intestine and its presence in small-intestinal crypt cells.

1988 ◽  
Vol 106 (6) ◽  
pp. 1937-1946 ◽  
Author(s):  
S U Gorr ◽  
B Stieger ◽  
J A Fransen ◽  
M Kedinger ◽  
A Marxer ◽  
...  
Keyword(s):  
Small Intestine ◽  
Light And Electron Microscopy ◽  
Extraction Procedure ◽  
Distal Colon ◽  
Adult Rats ◽  
Intestinal Crypt ◽  
Phase Partitioning ◽  
Microvillus Membrane ◽  
Small Intestinal ◽  
Crypt Cells

Murine mAbs were produced against purified microvillus membranes of rat colonocytes in order to establish a marker protein for this membrane. The majority of antibodies binding to the colonic microvillus membrane recognized a single protein with a mean apparent Mr of 120 kD in both proximal and distal colon samples. The antigen is membrane bound as probed by phase-partitioning studies using Triton X-114 and by the sodium carbonate extraction procedure and is extensively glycosylated as assessed by endoglycosidase F digestion. Localization studies in adult rats by light and electron microscopy revealed the microvillus membrane of surface colonocytes as the principal site of the immunoreaction. The antigen was not detectable in kidney or liver by immunoprecipitation but was present in the small intestine, where it was predominantly confined to the apical membrane of crypt cells and much less to the microvillus membrane of differentiated enterocytes. During fetal development, the antigen appears first in the colon at day 15 and 1-2 d later in the small intestine. In both segments, it initially covers the whole luminal surface but an adult-like localization pattern develops soon after birth. The antibodies were also used to develop a radiometric assay for the quantification of the antigen in subcellular fractions of colonocytes in order to assess the validity of a previously developed method for the purification of colonic brush-border membranes (Stieger, B., A. Marxer, and H.P. Hauri. 1986. J. Membr. Biol. 91:19-31.). The results suggest that we have identified a valuable marker glycoprotein for the colonic microvillus membrane, which in adult rats may also serve as a marker for early differentiation of enterocyte progenitor cells in small-intestinal crypt cells.

Myc and Max disassociate following polyamine depletion in small intestinal crypt cells

1998 ◽  
Vol 114 ◽  
pp. A891
Author(s):  
J. Li ◽  
L. Li ◽  
JN. Rao ◽  
BL. Bass ◽  
J-Y. Wang
Keyword(s):  
Intestinal Crypt ◽  
Small Intestinal ◽  
Crypt Cells

scholarly journals Co-localization of the Mammalian Hemochromatosis Gene Product (HFE) and a Newly Identified Transferrin Receptor (TfR2) in Intestinal Tissue and Cells

2003 ◽  
Vol 51 (5) ◽  
pp. 613-623 ◽  
Author(s):  
William J.H. Griffiths ◽  
Timothy M. Cox
Keyword(s):  
Transferrin Receptor ◽  
Iron Homeostasis ◽  
Receptor Gene ◽  
Hfe Gene ◽  
Transport Pathway ◽  
Intestinal Crypt ◽  
Hemochromatosis Gene ◽  
Small Intestinal ◽  
Potential Interactions ◽  
Crypt Cells

Mutations in the HFE gene and a newly identified second transferrin receptor gene, TfR2, cause hemochromatosis. The cognate proteins, HFE and TfR2, are therefore of key importance in human iron homeostasis. HFE is expressed in small intestinal crypt cells where transferrin-iron entry may determine subsequent iron absorption by mature enterocytes, but the physiological function of TfR2 is unknown. Using specific peptide antisera, we examined the duodenal localization of HFE and TfR2 in humans and mice, with and without HFE deficiency, by confocal microscopy. We also investigated potential interactions of these proteins in human intestinal cells in situ. Duodenal expression of HFE and TfR2 (but not TfR1) in wild-type mice and humans was restricted to crypt cells, in which they co-localized. HFE deficiency disrupted this interaction, altering the cellular distribution of TfR2 in human crypts. In human Caco-2 cells, HFE and TfR2 co-localized to a distinct CD63-negative vesicular compartment showing marked signal enhancement on exposure to iron-saturated transferrin ligand, indicating that HFE preferentially interacts with TfR2 in a specialized early endosomal transport pathway for transferrin-iron. This interaction occurs specifically in small intestinal crypt cells that differentiate to become iron-absorbing enterocytes. Our immunohistochemical findings provide evidence for a novel mechanism for the regulation of iron balance in mammals.

Identification of a 5-hydroxytryptamine (5-HT2) receptor on guinea pig small intestinal crypt cells

1993 ◽  
Vol 265 (2) ◽  
pp. G339-G346 ◽  
Author(s):  
A. K. Siriwardena ◽  
E. H. Smith ◽  
E. H. Borum ◽  
J. M. Kellum
Keyword(s):  
Guinea Pig ◽  
Dependent Manner ◽  
Maximal Inhibition ◽  
Concentration Dependent Manner ◽  
Intestinal Crypt ◽  
Mucosal Cells ◽  
Number Of Binding Sites ◽  
Small Intestinal ◽  
Ics 205 930 ◽  
Crypt Cells

Radioligand labeling of [3H]ketanserin was examined in suspensions of dispersed guinea pig small intestinal mucosal cells prepared by modification of the EDTA-chelation method described by M. M. Weiser (J. Biol. Chem. 248: 2536-2541, 1973). Preferential incorporation of [3H]thymidine was used to confirm that suspensions were enriched in crypt cells. At 25 degrees C, binding of [3H]ketanserin to dispersed enterocytes was rapid, maximal by 5 min, saturable (dissociation constant = 1.5 nM), 65 +/- 5% specific, stable, and reversible. The maximal number of binding sites per cell was 92,000 (range 86,000-105,500). Binding was temperature dependent, with maximal binding at 37 degrees C, and was inhibited by 5-hydroxytryptamine (5-HT) (half-maximal inhibition of [3H]ketanserin binding observed in response to 1 microM 5-HT) and ketanserin (half-maximal inhibition of [3H]ketanserin binding observed in response to 1 nM ketanserin) but not by the 5-HT1P antagonist N-acetyl-5-hydroxytryptophyl 5-hydroxytryptophan amide (5-HTP-DP) or the 5-HT3 antagonist 3-tropanyl-indole-3-carboxylate methiodide (ICS-205-930). The second messenger system coupled to the putative mucosal 5-HT2 receptor was examined. 5-HT stimulated a concentration-dependent production of inositol 1,4,5-trisphosphate (IP3) in the dispersed enterocytes. This was maximal at 1 min and was inhibited in a concentration-dependent manner by ketanserin. 5-HTP-DP and ICS-205-930 had no effect on 5-HT-stimulated production of IP3. These data provide evidence for the existence of a mucosal 5-HT2 receptor located on guinea pig small intestinal crypt cells.

Polyamine depletion is associated with an increase in JunD/AP-1 activity in small intestinal crypt cells

1999 ◽  
Vol 276 (2) ◽  
pp. G441-G450 ◽  
Author(s):  
Anami R. Patel ◽  
Jian-Ying Wang
Keyword(s):  
Cell Growth ◽  
Specific Inhibitor ◽  
Cell Types ◽  
Binding Activity ◽  
Activator Protein 1 ◽  
Intestinal Crypt ◽  
Regulate Cell Growth ◽  
Small Intestinal ◽  
Crypt Cells ◽  
Dialyzed Serum

Activator protein 1 (AP-1) is a group of dimeric transcription factors composed of protooncogene (Jun and Fos) subunits that bind to a common DNA site, the AP-1 binding site. The proteins of c-Jun, JunB, and Fos are essential for initiation of the cell cycle. Conversely, the activation of the junD gene slows cell growth in some cell types. The current study tests the hypothesis that polyamines influence cell growth by altering the balance of positive and negative Jun/AP-1 activities in intestinal epithelial cells. Studies were conducted in the IEC-6 cell line derived from rat small intestinal crypt cells. Administration of α-difluoromethylornithine (DFMO), a specific inhibitor for polyamine synthesis, for 4 and 6 days completely depleted cellular polyamine levels, while AP-1 binding activity was significantly increased. Spermidine, when given together with DFMO, restored AP-1 binding activity toward normal. The increased AP-1 complexes in polyamine-deficient cells were dramatically supershifted by the anti-JunD antibody but not by antibodies against c-Jun, JunB, or Fos proteins. There were significant increases in JunD mRNA and protein in DFMO-treated cells, although expression of the c- fos, c- jun, and junB genes decreased. The increase in JunD/AP-1 activity in DFMO-treated cells was associated with a significant decrease in cell division. Exposure of control quiescent cells to 5% dialyzed serum increased c-Jun/AP-1 but not JunD/AP-1 activities. DFMO prevented the stimulation of c-Jun/AP-1 activity induced by 5% dialyzed serum. These results indicate that 1) polyamine depletion is associated with an increase in AP-1 binding activity and 2) the increase in AP-1 activity in the DFMO-treated cells was primarily contributed by an increase in the JunD/AP-1. These findings suggest that polyamines regulate cell growth at least partially by modulating the balance of positive and negative Jun/AP-1 activities in the intestinal mucosa.

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