Transport of essential solutes across biological membranes is one of the fundamental characteristics of living cells. Although selenium is an essential micronutrient, little is known about the cellular mechanisms of chemical species-specific selenium transport in fish. We report here the kinetic and pharmacological transport characteristics of selenite and its thiol (glutathione and l-cysteine)...

We have explored the development of the brush border in adult chicken enterocytes by analyzing the cytoskeletal protein and mRNA levels as enterocytes arise from crypt stem cells and differentiate as they move toward the villus. At the base of the crypt, a small population of cells contain a rudimentary terminal web and a few short microvilli with long rootlets. These microvilli appear to arise...

Streptozotocin-induced (Type 1) diabetes mellitus (T1DM) in rats promotes jejunal glucose transport, but the trigger for this response remains unclear. Our recent work using euglycemic rats has implicated the enterocyte renin-angiotensin system (RAS) in control of sodium-dependent glucose transporter (SGLT1)-mediated glucose uptake across the jejunal brush border membrane (BBM). The aim of the ...

The effect of calcium upon the uptake of oleic acid solubilized with 10 mM taurocholate was investigated using an in vitro model of isolated enterocytes. The addition of Ca2+ to the incubation medium (Hanks' medium) led to a decrease in oleic-acid uptake. This uptake inhibition was dependent on both the amount of Ca2+ and the fatty-acid concentration, since the inhibitory effect was significant...

The role of class II major histocompatibility antigens in classical antigen-presenting cells has been described (Unanue (1984) Annu. Rev. Immunol. 2, 395-428; Watts and McConnell (1987) Rev. Immunol. 5, 461-475). Whether enterocytes, which also express class II antigens, can act as antigen-presenting cells in vivo is not known. One pre-requisite for a role for enterocytes in antigen presentatio...

Growth and differentiation of stem cells is thought to be regulated by growth factors and responding protein tyrosine kinase activities. Comparing mitotic stem cells from the adult intestinal epithelium, isolated from the crypts of Lieberkuhn, with isolated differentiated absorbtive cells we find major differences in the levels of phosphotyrosine-containing proteins. Crypt stem cells possess tw...

Enzymes within the CYP3A subfamily are major Phase I drug-metabolizing enzymes present in hepatocytes and small bowel enterocytes. These enzymes are highly inducible in the liver by many structurally diverse compounds, including a number of commonly used medications. Studies indicate that CYP3A enzymes present in small bowel enterocytes are also inducible. However, the regulation of CYP3A enzym...

Serum lipoproteins (LP) are increasingly being recognized as dual purpose molecules that contribute to both cholesterol homeostasis and host innate defense. In fact, very low LP levels are associated with increased risk of bacterial infection in critically ill patients. In this respect, we reported that apolipoprotein B100 (apoB100), the 4536 amino acid structural protein of very low density li...

It is generally believed that vitamin E is absorbed along with chylomicrons. However, we previously reported that human colon carcinoma Caco-2 cells use dual pathways, apolipoprotein B (apoB)-lipoproteins and HDLs, to transport vitamin E. Here, we used primary enterocytes and rodents to identify in vivo vitamin E absorption pathways. Uptake of [(3)H]alpha-tocopherol by primary rat and mouse ent...