Phosphate uptake in chick kidney cells: Effects of 1,25(OH)2D3 and 24,25(OH)2D3

Antiproliferative action of menadione and 1,25(OH)2D3 on breast cancer cells

“…Similarly, Banakar et al [33] have demonstrated that 1,25(OH) 2 D 3 elevates SOD activity in rat hepatocarcinogenesis induced by diethylnitrosamine. Khanal et al [34] have reported that 1,25(OH) 2 D 3 increases the specific activity of SOD and its protein level in intestinal epithelial and kidney cells from chicken. In contrast, Ravid et al [35] found a decrease in the SOD activity by calcitriol treatment of MCF-7 cells.…”

Novel hormone “receptors”

“…The protein, which we refer to as the 1,25D 3 -MARRS (membrane associated, rapid response steroid-binding) receptor was isolated on the basis of binding of isotopically labeled ligand [Nemere et al, 1994]. Using both antibodies (Ab 099 to 1,25D 3 -MARRS and 9A7 to the classical vitamin D receptor, VDR) and RNAi we demonstrated that the 1,25D 3 -MARRS receptor, and not the VDR is responsible for the nongenomic actions of 1,25(OH) 2 D 3 in chick intestine [Nemere et al, 2004] and kidney [Khanal et al, 2007]. That this is truly a cell surface protein was demonstrated by fluorescence activated cell sorting [Teillaud et al, 2005].…”

“…Purification of the protein and sequencing led to the identification of catalase as the binding protein [Larsson et al, 2006]. Binding of ligand to catalase resulted in a decrease in enzyme activity within 1 min that was evident even 5 h later [Khanal et al, 2007] . Binding to the VDR was not affected in the same samples.…”

Effect of 24,25-dihydroxyvitamin D3 on localization of catalase in chick enterocytes

“…The ability of 24,25(OH) 2 D 3 to inhibit 1,25D 3 -MARRS receptor activation of protein kinase A and C activities was found in chick intestine [12] and kidney [4], which indicates the existence of a specific binding protein for 24,25(OH) 2 [10]. In order to explain how 24,25(OH) 2 D 3 works to effect inhibition, a cellular binding protein (66 kDa) was isolated, purified [10] and sequenced [13].…”

“…The enzyme catalase is sensitive to cell signaling molecules [14]. It was found that the inhibitory action of 24,25(OH) 2 D 3 is caused by a decrease in catalase activity in both chick intestine [15,16] and kidney [12], accompanied by an increase in H 2 O 2 production [13]. Thus, one possible mechanism for the inhibitory action would be the oxidation of thioredoxin domains in 1,25D 3 -MARRS receptor that occurred after 10 min of exposure [15], accompanied by a loss of binding activity.…”