scholarly journals Secretion of human intestinal angiotensin-converting enzyme and its association with the differentiation state of intestinal cells

1996 ◽  
Vol 316 (1) ◽  
pp. 259-264 ◽  
Author(s):  
Hassan Y. NAIM
Keyword(s):  
Epithelial Cells ◽  
Lectin Binding ◽  
Critical Role ◽  
Intestinal Epithelial ◽  
Converting Enzyme ◽  
Binding Studies ◽  
Glycosylation Pattern ◽  
Differentiated Cells ◽  
Mucosal Cells ◽  
Well Differentiated

Human angiotensin I-converting enzyme (ACE) exists in intestinal epithelial cells as a membrane-bound (ACEm) and secretory glycoprotein (ACEsec). The electrophoretic mobilities of ACEsec and ACEm on SDS/polyacrylamide gels are similar; the N-deglycosylated ACEsec and ACEm, in contrast, display slight differences in their apparent molecular masses, indicating that the carbohydrate contents of ACEsec and ACEm are different. Moreover, ACEsec is solely N-glycosylated whereas ACEm is N- and O-glycosylated, assessed by lectin binding studies. Spontaneous release of ACEsec is achieved by incubation of brush border membranes at 37 °C. Aprotinin, leupeptin and EDTA partly inhibit the generation of ACEsec, strongly suggesting that ACEsec is generated from ACEm by proteolytic cleavage. The expression levels of ACEsec in the intestine may be associated with the differentiation state of mucosal cells. Thus ACEsec is more abundant than ACEm in immature non-epithelial crypt cells of patients with coeliac disease. Well-differentiated epithelial cells, by contrast, contain predominantly ACEm. The variations in the proportions of cleaved ACEsec in differentiated and non-differentiated cells may be due to varying levels of the cleaving protease. Alternatively, because epithelial cell differentiation is accompanied by alterations in the levels of oligosaccharyltransferases, the results suggest a critical role for the glycosylation pattern of ACEm in its susceptibility to the putative cleaving protease.

Glucose and glutamine provide similar proportions of energy to mucosal cells of rat small intestine

1997 ◽  
Vol 273 (4) ◽  
pp. G968-G978 ◽  
Author(s):  
Sharon E. Fleming ◽  
Kirsten L. Zambell ◽  
Mark D. Fitch
Keyword(s):  
Small Intestine ◽  
Epithelial Cells ◽  
Metabolic Pathways ◽  
Glycolytic Flux ◽  
Net Energy ◽  
Intestinal Epithelial ◽  
Atp Production ◽  
Distal Small Intestine ◽  
Mucosal Cells ◽  
In Cells

The objectives of this study were to establish a reliable method for quantifying glycolytic flux in intestinal epithelial cells, to determine the proportion of energy provided to small intestine epithelial cells by glucose vs. glutamine, and to determine whether there was an energetic advantage to having both substrates present simultaneously. There was substantial retention of 3H in alanine and lactate when [2-3H]glucose was used as tracer for quantifying glycolysis, and the magnitude of the3H retention was influenced by the presence of other substrates and metabolites. Detritiation was at least 99% complete, however, when [3-3H]glucose was used as tracer in this system and the tritium was recovered as3H2O. Glycolytic flux was six- to sevenfold higher in cells of the proximal than distal small intestine but was not significantly different for young adult (4 mo) vs. aged adult (24 mo) rats. Net ATP production from exogenous substrates was higher when both glucose and glutamine were present simultaneously than when either substrate was present alone, and glucose was calculated to provide 50–60% of the net ATP produced from these two substrates. Most of the energy produced from glucose was produced via the anaerobic metabolic pathways (78% for glucose alone, 95% with glucose and glutamine). Net energy production was calculated to be 10% lower in cells from aged animals than in those from young animals, since CO2 production from these major substrates was lower in cells from aged animals.

Nitric oxide regulates energy metabolism and Bcl-2 expression in intestinal epithelial cells

1998 ◽  
Vol 274 (5) ◽  
pp. G797-G801 ◽  
Author(s):  
Manabu Nishikawa ◽  
Kenta Takeda ◽  
Eisuke F. Sato ◽  
Tetso Kuroki ◽  
Masayasu Inoue
Keyword(s):  
Nitric Oxide ◽  
Epithelial Cells ◽  
Prolonged Exposure ◽  
Intestinal Epithelial Cells ◽  
Enteric Bacteria ◽  
Intestinal Lumen ◽  
Intestinal Epithelial ◽  
Mucosal Cells ◽  
Respiration Of Mitochondria ◽  
Induced Changes

Nitric oxide (NO) inhibits the respiration of mitochondria and enteric bacteria, particularly under low O2concentration, and induces apoptosis of various types of cells. To gain insight into the molecular role of NO in the intestine, we examined its effects on the respiration, Ca2+status, and expression of Bcl-2 in cultured intestinal epithelial cells (IEC-6). NO reversibly inhibited the respiration of IEC-6 cells, especially under physiologically low O2concentration. Although NO elevated cytosolic Ca2+as determined by the fura 2 method, the cells were fairly resistant to NO. Kinetic analysis revealed that prolonged exposure to NO elevated the levels of Bcl-2 and suppressed the NO-induced changes in Ca2+status of the cells. Because Bcl-2 possesses antiapoptotic function, toxic NO effects might appear minimally in enterocytes enriched with Bcl-2. Thus NO might effectively exhibit its antibacterial action in anaerobic intestinal lumen without inducing apoptosis of Bcl-2-enriched mucosal cells.

TRPC1 functions as a store-operated Ca2+ channel in intestinal epithelial cells and regulates early mucosal restitution after wounding

2006 ◽  
Vol 290 (4) ◽  
pp. G782-G792 ◽  
Author(s):  
Jaladanki N. Rao ◽  
Oleksandr Platoshyn ◽  
Vera A. Golovina ◽  
Lan Liu ◽  
Tongtong Zou ◽  
...  
Keyword(s):  
Cell Migration ◽  
Epithelial Cells ◽  
Transient Receptor Potential ◽  
Intestinal Epithelial Cells ◽  
Critical Role ◽  
Receptor Potential ◽  
Mucosal Injury ◽  
Intestinal Epithelial ◽  
Epithelial Restitution ◽  
Transient Receptor

An increase in cytosolic free Ca2+ concentration ([Ca2+]cyt) results from Ca2+ release from intracellular stores and extracellular Ca2+ influx through Ca2+-permeable ion channels and is crucial for initiating intestinal epithelial restitution to reseal superficial wounds after mucosal injury. Capacitative Ca2+ entry (CCE) induced by Ca2+ store depletion represents a major Ca2+ influx mechanism, but the exact molecular components constituting this process remain elusive. This study determined whether canonical transient receptor potential (TRPC)1 served as a candidate protein for Ca2+-permeable channels mediating CCE in intestinal epithelial cells and played an important role in early epithelial restitution. Normal intestinal epithelial cells (the IEC-6 cell line) expressed TRPC1 and TPRC5 and displayed typical records of whole cell store-operated Ca2+ currents and CCE generated by Ca2+ influx after depletion of intracellular stores. Induced TRPC1 expression by stable transfection with the TRPC1 gene increased CCE and enhanced cell migration during restitution. Differentiated IEC-Cdx2L1 cells induced by forced expression of the Cdx2 gene highly expressed endogenous TRPC1 and TRPC5 and exhibited increased CCE and cell migration. Inhibition of TRPC1 expression by small interfering RNA specially targeting TRPC1 not only reduced CCE but also inhibited cell migration after wounding. These findings strongly suggest that TRPC1 functions as store-operated Ca2+ channels and plays a critical role in intestinal epithelial restitution by regulating CCE and intracellular [Ca2+]cyt.

scholarly journals Critical role of type III interferon in controlling SARS-CoV-2 infection, replication and spread in primary human intestinal epithelial cells

2020 ◽  
Author(s):  
Megan L. Stanifer ◽  
Carmon Kee ◽  
Mirko Cortese ◽  
Sergio Triana ◽  
Markus Mukenhirn ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
De Novo ◽  
Intestinal Epithelial Cells ◽  
Critical Role ◽  
Type I ◽  
Intestinal Epithelial ◽  
Virus Particles ◽  
Type Iii ◽  
Human Intestinal Epithelial Cells ◽  
Type Iii Interferon

SummarySARS-CoV-2 is an unprecedented worldwide health problem that requires concerted and global approaches to better understand the virus in order to develop novel therapeutic approaches to stop the COVID-19 pandemic and to better prepare against potential future emergence of novel pandemic viruses. Although SARS-CoV-2 primarily targets cells of the lung epithelium causing respiratory infection and pathologies, there is growing evidence that the intestinal epithelium is also infected. However, the importance of the enteric phase of SARS-CoV-2 for virus-induced pathologies, spreading and prognosis remains unknown. Here, using both colon-derived cell lines and primary non-transformed colon organoids, we engage in the first comprehensive analysis of SARS-CoV-2 lifecycle in human intestinal epithelial cells. Our results demonstrate that human intestinal epithelial cells fully support SARS-CoV-2 infection, replication and production of infectious de-novo virus particles. Importantly, we identified intestinal epithelial cells as the best culture model to propagate SARS-CoV-2. We found that viral infection elicited an extremely robust intrinsic immune response where, interestingly, type III interferon mediated response was significantly more efficient at controlling SARS-CoV-2 replication and spread compared to type I interferon. Taken together, our data demonstrate that human intestinal epithelial cells are a productive site of SARS-CoV-2 replication and suggest that the enteric phase of SARS-CoV-2 may participate in the pathologies observed in COVID-19 patients by contributing in increasing patient viremia and by fueling an exacerbated cytokine response.

scholarly journals Critical Role of Type III Interferon in Controlling SARS-CoV-2 Infection in Human Intestinal Epithelial Cells

Cell Reports ◽  
2020 ◽  
Vol 32 (1) ◽  
pp. 107863 ◽  
Author(s):  
Megan L. Stanifer ◽  
Carmon Kee ◽  
Mirko Cortese ◽  
Camila Metz Zumaran ◽  
Sergio Triana ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Critical Role ◽  
Intestinal Epithelial ◽  
Type Iii ◽  
Human Intestinal Epithelial Cells ◽  
Type Iii Interferon

scholarly journals EFFECTS OF PUROMYCIN ON THE STRUCTURE OF RAT INTESTINAL EPITHELIAL CELLS DURING FAT ABSORPTION

1972 ◽  
Vol 52 (1) ◽  
pp. 15-40 ◽  
Author(s):  
Harold I. Friedman ◽  
Robert R. Cardell
Keyword(s):  
Epithelial Cells ◽  
Golgi Complex ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Fat Absorption ◽  
Absorptive Cell ◽  
Golgi Membranes ◽  
Mucosal Cells ◽  
Chylomicron Formation

This report provides information on the morphology of rat intestinal epithelial cells during fat absorption. In addition, the role of protein metabolism in this process has been evaluated by blocking its synthesis with puromycin and studying the fine structure of mucosal cells from rats at various times after fat intubation. The results indicate that SER-derived vesicles, containing fat droplets, migrate from the apical cytoplasm of the absorptive cell and fuse with saccules or vacuoles of the Golgi complex. Arguments are made that the Golgi complex is important in completing chylomicron formation and in providing appropriate enveloping membranes for the chylomicron. Such membranes may be necessary for Golgi vacuoles to fuse with the lateral cell membranes and release chylomicra. Puromycin treatment causes the absorptive cell to accumulate increased quantities of lipid that are devoid of membrane during fat absorption. In addition, puromycin-treated cells contain much less RER and Golgi membranes are strikingly decreased in number. In this paper we discuss the consequences of these abnormalities and suggest that continued protein synthesis by the RER is required in order to generate Golgi membranes. If such membranes are absent the cell's ability to discarge chylomicra is impaired and lipid accumulates.

scholarly journals Induced TRPC1 expression sensitizes intestinal epithelial cells to apoptosis by inhibiting NF-κB activation through Ca2+ influx

2006 ◽  
Vol 397 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Bernard S. Marasa ◽  
Jaladanki N. Rao ◽  
Tongtong Zou ◽  
Lan Liu ◽  
Kaspar M. Keledjian ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Transient Receptor Potential ◽  
Intestinal Epithelial Cells ◽  
Critical Role ◽  
Ectopic Expression ◽  
Receptor Potential ◽  
Nuclear Factor Κb ◽  
Intestinal Epithelial ◽  
Store Depletion ◽  
Increased Susceptibility

Apoptosis occurs within crypts and at the intestinal luminal surface and plays a critical role in mucosal homoeostasis. NF-κB (nuclear factor-κB) is the central regulator of the transcription of genes involved in apoptosis, and its activity is highly regulated in the intestinal mucosa. We have recently demonstrated that TRPC1 (transient receptor potential canonical-1) is expressed in IECs (intestinal epithelial cells) and functions as a Ca2+ permeable channel activated by Ca2+ store depletion. The present study tests the hypothesis that TRPC1 channels are implicated in the regulation of apoptosis by inhibiting NF-κB through the induction of TRPC1-mediated Ca2+ influx in the IEC-6 line. The expression of TRPC1 induced by stable transfection of IEC-6 cells with the wild-type TRPC1 gene (IEC-TRPC1 cells) increased Ca2+ influx after Ca2+ store depletion and repressed NF-κB transactivation, which was associated with an increase in susceptibility to apoptosis induced by exposure to TNFα (tumour necrosis factor-α) plus CHX (cycloheximide) (TNF-α/CHX), or STS (staurosporine). By contrast, the induction of endogenous NF-κB activity, by the depletion of cellular polyamines, promoted resistance to apoptosis, which was prevented by the ectopic expression of the IκBα super-repressor. Furthermore, inhibition of TRPC1 expression by transfection with siRNA (small interfering RNA) targeting TRPC1 (siTRPC1) decreased Ca2+ influx, increased NF-κB transactivation, and prevented the increased susceptibility of IEC-TRPC1 cells to apoptosis. Decreasing Ca2+ influx by exposure to a Ca2+-free medium also induced NF-κB activity and blocked the increased susceptibility to apoptosis of stable IEC-TRPC1 cells. These results indicate that induced TRPC1 expression sensitizes IECs to apoptosis by inhibiting NF-κB activity as a result of the stimulation of Ca2+ influx.

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