A cDNA was isolated from rat C6 glioma cells by expression cloning which encodes a novel Na+-independent neutral amino acid transporter designated LAT1. For functional in Xenopus oocytes, LAT1 required the heavy chain of 4F2 cell surface antigen (CD98), type II membrane glycoprotein. When co-expressed with chain, transported acids branched or aromatic side chains and did not accept basic acidic acids. The transport via sensitive to system L-specific inhibitor...

We have isolated a cDNA from rat small intestine that encodes novel Na+-independent neutral amino acid transporter with distinctive characteristics in substrate selectivity and transport property. The encoded protein, designated L-type transporter-2 (LAT-2), shows sequence similarity to the system L LAT-1 (Kanai, Y., Segawa, H., Miyamoto, K., Uchino, Takeda, E., Endou, H. (1998) J. Biol. Chem. 273, 23629-23632) (50% identity) y+L transporters y+LAT-1 (47%) KIAA0245/y+LAT-2 (45%) (Torrents,...

Fibroblast growth factor-23 (FGF-23), a novel phosphate-regulating factor, was elevated in hypophosphatemic patients with X-linked rickets/osteomalacia and also chronic kidney disease. These observations suggested the pathophysiological importance of FGF-23 on phosphate homeostasis. However, regulation production is still unclear. We investigated effects both dietary phosphorus 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) circulating vivo Administration of. 1α,25(OH)2D3 dose-dependently...

The human fibroblast growth factor 23 (hFGF23) and its autosomal dominant hypophosphatemic rickets (ADHR) mutant genes were incorporated into animals by naked DNA injection to investigate the action on phosphate homeostasis <i>in vivo</i>. hFGF23 mutants (R176Q, R179Q, R179W) markedly reduced serum phosphorus (6.2–6.9 mg/dl) compared with plasmid MOCK (8.5 mg/dl). However, native did not affect (8.6 Both hFGF23R179Q mRNAs expressed more than 100-fold in liver 4 days after injection, however,...

Growth is critically dependent on the retention of a variety nutrients. The kidney contributes to this positive external balance. In present study, we isolated cDNA from human and rat that encodes growth-related Na(+)-dependent inorganic phosphate (P(i)) cotransporter (type IIc). Microinjection type IIc cRNA into Xenopus oocytes demonstrated sodium-dependent P(i) cotransport activity. Affinity for was 0.07 mm in 100 Na(+). transport activity extracellular pH. electrophysiological studies,...

A cDNA was isolated from the mouse brain that encodes a novel Na+-independent neutral amino acid transporter. The encoded protein, designated as Asc-1 (asc-type transporter 1), found to be structurally related recently identified mammalian transporters for transport systems L, y+L, xC−, and b0,+, which are linked, via disulfide bond, type II membrane glycoproteins, 4F2 heavy chain (4F2hc), or rBAT (related b0,+ transporter). required 4F2hc its functional expression. In Western blot analysis...

Recent studies suggest that vitamin D may play a role in intestinal Na(+)-dependent phosphate transport adaptation to variable levels of dietary P(i). Therefore, the goal current study was assess P(i) cotransport activity transgenic mice determine whether is an essential mediator this process. Intestinal brush-border membrane (BBM), significantly decreased receptor (VDR) null [VDR (-/-)] compared with wild-type (VDR+/+) mice. While Na-P(i) cotransporter (type IIb) mRNA were similar VDR (-/-)...

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare autosomal recessively inherited disorder, characterized by hypophosphatemia, short stature, and/or osteomalacia, and secondary absorptive hypercalciuria. HHRH caused defect in the sodium-dependent phosphate transporter (NaPi-IIc/Npt2c/NPT2c), which was thought to have only minor role renal (P(i)) reabsorption adult mice. In fact, mice that are null for Npt2c (Npt2c(-/-)) show no evidence wasting when maintained on diet...

We identified an amino acid transporter that is associated with the cystinuria-related type II membrane glycoprotein, rBAT (related to b^0,+ transporter). The designated BAT1 (b^0,+-type 1) from rat kidney was found be structurally related recently transporters for system L, y⁺L, and x⁻C, which are linked, via a disulfide bond, other 4F2hc (4F2 heavy chain). In nonreducing condition, 125-kDa band, seems correspond heterodimeric complex of rBAT,...

In a study of the rat intestinal P(i) transport system, an activator protein for Na/P(i) co-transport system (PiUS) was isolated and characterized. We also investigated effects restriction vitamin D (two most important physiological pathophysiological regulators absorption in small intestine) on activity expression co-transporters that are expressed intestine. Rat PiUS encodes 424-residue with calculated molecular mass 51463 Da. The microinjection into Xenopus oocytes markedly stimulated...

FGF23 (fibroblast growth factor 23) is a novel phosphaturic that influences vitamin D metabolism and renal re-absorption of Pi. The goal the present study was to characterize role VDR (vitamin receptor) in action using VDR(−/−) (VDR null) mice. Injection FGF23M (naked DNA encoding R179Q mutant human FGF23) into wildtype VDR(+/+) mice resulted an elevation serum levels, but had no effect on calcium or parathyroid hormone levels. In contrast, injection significant decreases Pi Na/Pi...

Recent studies have demonstrated that klotho protein plays a role in calcium/phosphate homeostasis. The goal of the present study was to investigate regulation Na-P(i) cotransporters mutant (kl/kl) mice. kl/kl mice displayed hyperphosphatemia, high plasma 1,25(OH)(2)D(3) levels, increased activity renal and intestinal sodium-dependent P(i) cotransporters, levels type IIa, IIb, IIc transporter proteins compared with wild-type Interestingly, transcript IIa/type mRNA abundance, but not...

Hereditary hypophosphatemic rickets with hypercalciuria results from mutations of the renal type IIc Na-P(i) cotransporter gene, suggesting that transporter plays a prominent role in phosphate handling. The goal present study was to investigate regulation by parathyroid hormone (PTH). Type levels were markedly increased thyroparathyroidectomized (TPTX) rats. Four hours after administration PTH, protein decreased apical membrane fraction but recovered baseline at 24 h. Immunohistochemical...

Vitamin D is an important regulator of phosphate homeostasis. The effects vitamin on the expression renal Na+-dependent inorganic (Pi) transporters (types I and II) were investigated. In D-deficient rats, amounts type II Pi transporter (NaPi-2) protein mRNA decreased in juxtamedullary kidney cortex, but not superficial compared with control rats. administration 1,25-dihydroxyvitamin D3(1,25-(OH)2D3) to rats increased initial rate uptake as well NaPi-2 cortex. transcriptional activity a...

Abstract: The mechanisms by which fibroblast growth factor 23 (FGF23) alters inorganic phosphate (Pi) homeostasis is not entirely clear. In the present study, we examined effect of FGF23 on intestinal sodium‐dependent Pi transport in mice. Injection FGF23(R179Q) markedly reduced serum and 1,25(OH) 2 D 3 levels normal Those animals show reduction activity amount type IIb cotransporter (type NaPi) protein brush border membrane vesicles. vitamin receptor null mice (VDR−/−), had no NaPi levels....

Primary renal inorganic phosphate (Pi) wasting leads to hypophosphatemia, which is associated with skeletal mineralization defects. In humans, mutations in the gene encoding type IIc sodium–dependent transporter lead hereditary hypophophatemic rickets hypercalciuria, but whether Pi directly causes bone disorder unknown. Here, we generated Npt2c-null mice define contribution of Npt2c homeostasis and abnormalities. Homozygous mutants (Npt2c−/−) exhibited hypercalcemia, elevated plasma...

Fibroblast growth factor-23 (FGF-23) has been recently identified as playing an important pathophysiological role in phosphate homeostasis and vitamin D metabolism. To elucidate the precise physiological regulation of FGF-23, we characterized mouse FGF-23 5'-flanking region analyzed its promoter activity. The gene contained a TFIID site (TATA box) several putative transcription factor binding sites, including MZF1, GATA-1 c-Ets-1 motifs, but it did not contain typical sequences response...

Agonist-induced phosphorylation of the parathyroid hormone (PTH) receptor 1 (PTHR1) regulates signaling in vitro, but role this vivo is uncertain. We investigated by injecting "knock-in" mice expressing a phosphorylation-deficient (PD) PTHR1 with PTH ligands and assessing acute biologic responses. Following injection (1-34), or unique, long-acting analog, PD mice, compared WT exhibited enhanced increases cAMP levels blood, as well production gene expression responses bone kidney tissue....

The present study was undertaken to define the mechanisms governing regulation of novel renal brush-border membrane (BBM) Na-phosphate (P i ) cotransporter designated type IIc (Npt2c). To address this issue, expression Npt2c compared in two hypophosphatemic mouse models with impaired BBM Na-P cotransport. In mice homozygous for disrupted Npt2a gene ( Npt2 – / ), protein abundance, relative actin, increased 2.8-fold +/+ littermates, whereas a corresponding increase mRNA β-actin, not evident....

The extracellular concentration of inorganic phosphate (Pi) is an important determinant parathyroid cell function. effects Pi may be mediated through specific molecules in the membrane, one candidate molecule for which would a Na+-dependent cotransporter. A complementary DNA encoding Na+-Pi cotransporter, termed rat PiT-1, has now been isolated from parathyroid. 2890-bp encodes protein 681 amino acids that shows sequence identities 97% and 93% with type III cotransporters mouse PiT-1 human...

Dietary phosphate levels regulate the renal brush-border type IIa Na-Pi cotransporter. Another cotransporter, IIc, colocalizes with cotransporter in apical membrane of proximal tubular cells. The goal present study was to determine whether dietary also rapidly IIc Type and transporter protein were increased rats chronically fed a low-Pi diet compared those normal-Pi diet. Two hours after beginning high-Pi diet, decreased, whereas remained unchanged. Western blot analysis prepared 4 h showed...