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Systemic inflammation causes malaise and general feelings of discomfort. This fundamental aspect of the sickness response reduces the quality of life for people suffering from chronic inflammatory diseases and is a nuisance during mild infections like common colds or the flu. To investigate how inflammation is perceived as unpleasant and causes negative affect, we used a behavioral test in which mice avoid an environment that they have learned to associate with inflammation-induced discomfort. Using a combination of cell-type-specific gene deletions, pharmacology, and chemogenetics, we found that systemic inflammation triggered aversion through MyD88-dependent activation of the brain endothelium followed by COX1-mediated cerebral prostaglandin [E.sub.2] ([PGE.sub.2]) synthesis. Further, we showed that inflammation- induced [PGE.sub.2] targeted EP1 receptors on striatal dopamine D1 receptor-expressing neurons and that this signaling sequence induced aversion through GABA-mediated inhibition of dopaminergic cells. Finally, we demonstrated that inflammation-induced aversion was not an indirect consequence of fever or anorexia but that it constituted an independent inflammatory symptom triggered by a unique molecular mechanism. Collectively, these findings demonstrate that [PGE.sub.2]-mediated modulation of the dopaminergic motivational circuitry is a key mechanism underlying the negative affect induced by inflammation., Introduction Upon inflammation, an array of brain-mediated responses occurs. They are collectively referred to as the sickness syndrome and include fever, decreased food intake, inactivity, social withdrawal, and corticosteroid secretion [...]

A recent study published in the journal Diabetes suggests that a polymorphism in the AKR1A1 gene may be associated with diabetic kidney disease (DKD). The study used transcriptomics and proteomics data to identify concordant gene-protein pairs that were changed in a similar direction with DKD. However, it is unclear whether altered protein expression is a cause or effect of DKD. The study also found that the AKR1A1 polymorphism is associated with increased serum cystatin C, a marker of glomerular filtration rate. Further research is needed to understand the role of AKR1A1 in DKD and identify potential therapeutic targets. [Extracted from the article]

The FGF23 coreceptor αKlotho (αKL) is expressed as a membrane-bound protein (mKL) that forms hetero-meric complexes with FGF receptors (FGFRs) to initiate intracellular signaling. It also circulates as an endo-proteolytic cleavage product of mKL (cKL). Previously, a patient with increased plasma cKL as the result of a translocation [t(9;13)] in the _KLOTHO (KL) gene presented with rickets and a complex endocrine profile, including paradoxically elevated plasma FGF23, despite hypophosphatemia. The goal of this study was to test whether cKL regulates phosphate handling through control of FGF23 expression. To increase cKL levels, mice were treated with an adeno-associated virus producing cKL. The treated groups exhibited dose-dependent hypophosphatemia and hypocalcemia, with markedly elevated FGF23 (38 to 456 fold). The animals also manifested fractures, reduced bone mineral content, expanded growth plates, and severe osteomalacia, with highly increased bone Fgf23 mRNA (>150 fold). cKL activity in vitro was specific for interactions with FGF23 and was FGFR dependent. These results demonstrate that cKL potently stimulates FGF23 production in vivo, which phenocopies the KL translocation patient and metabolic bone syndromes associated with elevated FGF23. These findings have important implications for the regulation of αKL and FGF23 in disorders of phosphate handling and biomineralization., Introduction The bone-derived hormone FGF23 and its coreceptor αKlotho (αKL) are critical regulators of systemic phosphate metabolism. The αKL gene product is expressed as multiple species; the membrane-bound form (mKL) [...]

Sirtuin 1 (Sirt1) is a [NAD.sup.+]-dependent deacetylase that exerts many of the pleiotropic effects of oxidative metabolism. Due to local hypoxia and hypertonicity, the renal medulla is subject to extreme oxidative stress. Here, we set out to investigate the role of Sirt1 in the kidney. Our initial analysis indicated that it was abundantly expressed in mouse renal medullary interstitial cells in vivo. Knocking down Sirt1 expression in primary mouse renal medullary interstitial cells substantially reduced cellular resistance to oxidative stress, while pharmacologic Sirt1 activation using either resveratrol or SRT2183 improved cell survival in response to oxidative stress. The unilateral ureteral obstruction (UUO) model of kidney injury induced markedly more renal apoptosis and fibrosis in [Sirt1.sup.±] mice than in wild-type controls, while pharmacologic Sirt1 activation substantially attenuated apoptosis and fibrosis in wild-type mice. Moreover, Sirt1 deficiency attenuated oxidative stress-induced COX2 expression in cultured mouse renal medullary interstitial cells, and [Sirt1.sup.±] mice displayed reduced UUO-induced COX2 expression in vivo. Conversely, Sirt1 activation increased renal medullary interstitial cell COX2 expression both in vitro and in vivo. Furthermore, exogenous PGE2 markedly reduced apoptosis in Sirt1-deficient renal medullary interstitial cells following oxidative stress. Taken together, these results identify Sirt1 as an important protective factor for mouse renal medullary interstitial cells following oxidative stress and suggest that the protective function of Sirt1 is partly attributable to its regulation of COX2 induction. We therefore suggest that Sirt1 provides a potential therapeutic target to minimize renal medullary cell damage following oxidative stress., Introduction The renal medulla, one of the harshest environments in the body, is characterized by excessive oxidative stress that results from rapidly changing interstitial tonicity as well as low blood [...]

The present studies examined the relationship between fasting blood glucose and Hb [A.sub.1c] in C57BL/6J, DBA/2J, and KK/H1J mice with and without diabetes mellitus. Daily averaged blood glucose levels based on continuous glucose monitoring and effects of 6-h vs. overnight fasting on blood glucose were determined. Daily averaged blood glucose levels were highly correlated with Hb [A.sub.1c], as determined with a hand-held automated device using an immunodetection method. [R.sup.2] values were 0.90, 0.95, and 0.99 in KK/HIJ, C57BL/6J, and DBA/2J, respectively. Six-hour fasting blood glucose correlated more closely with the level of daily averaged blood glucose and with Hb [[A.sub.1c] than did blood glucose following an overnight fast. To validate the immunoassay-determined Hb [A.sub.1c], we also measured total glycosylated hemoglobin using boronate HPLC. Hb [A.sub.1c] values correlated well with total glycosylated hemoglobin in all three strains but were relatively lower than total glycosylated hemoglobin in diabetic DBA/2J mice. These results show that 6-h fasting glucose provides a superior index of glycemic control and correlates more closely with Hb [A.sub.1c] than overnight-fasted blood glucose in these strains of mice. glycosylated hemoglobin; methodology; mice

Hyperlipidemia is one of the major features of nephrotic syndrome (NS). Although many factors have been implicated in the pathogenesis of NS-related dyslipidemia, the underlying mechanisms remain largely uncharacterized. The present study was designed to examine the gene profile associated with lipid metabolism in the livers of nephrotic rats. NS was created in male Sprague-Dawley rats (n = 6) receiving sequential intraperitoneal injections of puromycin aminonucleoside. Analysis by Affymetrix assay, quantitative RT-PCR, and Northern and Western blotting revealed 21 genes associated with cholesterol and fatty acid metabolism. Eight genes involved in cholesterol metabolism, Apo A-I, Acly, Acat, Mpd, Fdps, Ss, Lss, and Nsdhl, were significantly upregulated under NS. Four genes involved in fatty acid biosynthesis, Acc, FAS, ELOVL 2, and ELOVL6, and three critical for triglyceride biosynthesis, Gpam, Agpat 3, and Dgat 1, were significantly upregulated, whereas two genes involved in fatty acid oxidation, Dci and MCAD, were downregulated. Expression of several genes in sterol-regulatory element-binding protein (SREBP)-1 activation was also aberrantly altered in nephrotic livers. The expression and transcriptional activity of SREBP-1 but not SREBP-2 were increased in nephrotic rats as assessed by real-time PCR, immunoblotting, and gel shift assays. The upregulation of hepatic genes involved in cholesterol biosynthesis may play an important role in the pathogenesis of hypercholesterolemia, whereas upregulation of genes participating in hepatic fatty acid and triglyceride biosynthesis and downregulation of genes involved in hepatic fatty acid oxidation may contribute to hypertriglyceridemia in nephrotic rats. Activation of SREBP-1 transcription factor may represent an underlying molecular mechanism of hyperlipidemia in NS. microarrays; nephrotic syndrome; lipid

Clinical use of prostaglandin synthase-inhibiting NSAIDs is associated with the development of hypertension; however, the cardiovascular effects of antagonists for individual prostaglandin receptors remain uncharacterized. The present studies were aimed [...]

The complex cytoarchitecture of the podocyte is critical for glomerular permselectivity. The present study characterizes the expression of nestin, an intermediate filament protein, in human kidneys. In normal kidneys, nestin was detected at the periphery of glomerular capillary loops. Colabeling showed nestin was expressed in WT1-positive cells. Within the podocyte, nestin immunoreactivity was present in the cell body and primary process. This was supported by immunoelectron microscopy. Nestin also colocalized with vimentin in the periphery of capillary loops but not in the mesangium. Nestin was not detected in other structures of the adult human kidney. To determine the potential role of nestin in proteinuria, nestin was examined in kidney biopsies from patients with or without proteinuria. These patients were diagnosed with IgA nephropathy with mild mesangial expansion but without proteinuria, IgA nephropathy with proteinuria, membranous nephropathy (MN), and focal segmental glomerular sclerosis (FSGS). The distribution of nestin in these biopsies was similar to that in the normal kidney. Semiquantitative analysis of immunostaining showed that glomerular nestin expression in IgA nephropathy without proteinuria was not different from normal kidney; however, nestin expression in kidneys of patients with IgA nephropathy and proteinuria, or MN and FSGS with proteinuria was significantly reduced compared with normal kidney (P < 0.01). Reduced nestin mRNA expression in the patients with IgA nephropathy with proteinuria and FSGN was also observed by quantitative real-time PCR. These studies suggest that nestin may play an important role in maintaining normal podocyte function in the human kidney. IgA nephropathy; proteinuria; cytoskeletal protein doi: 10.1152/ajpregu.00319.2006.

We investigated the role of the prostaglandin [E.sub.2] (PG[E.sub.2]) E[P.sub.1] receptor in modulating urine concentration as it is expressed along the renal collecting duct where arginine-vasopressin (AVP) exerts its anti-diuretic activity, and in the paraventricular and supraoptic nuclei of the hypothalamus where AVP is synthesized. The urine osmolality of E[P.sub.1]-null mice (E[P.sub.1.sup.-/-]) failed to match levels achieved by wild-type (WT) counterparts upon water deprivation (WD) for 24 h. This difference was reflected by higher plasma osmolality in WD E[P.sub.1.sup.-/-] mice. Along the collecting duct, the induction and subapical to plasma membrane translocation of the aquaporin-2 water channel in WD E[P.sub.1.sup.-/-] mice appeared equivalent to that of WD WT mice as determined by quantitative RT-PCR and immunohistochemistry. However, medullary interstitial osmolalities dropped significantly in E[P.sub.1.sup.-/-] mice following WD. Furthermore, urinary AVP levels of WD E[P.sub.1.sup.-/-] mice were significantly lower than those of WD WT mice. This deficit could be traced back to a blunted induction of hypothalamic AVP mRNA expression in WD E[P.sub.1.sup.-/-] mice as determined by quantitative RT-PCR. Administration of the AVP mimetic [deamino-[Cys.sup.1],D-[Arg.sup.8]]-vasopressin restored a significant proportion of the urine concentrating ability of WD E[P.sub.1.sup.-/-] mice. When mice were water loaded to suppress endogenous AVP production, urine osmolalities increased equally for WT and E[P.sub.1.sup.-/-] mice. These data suggest that PG[E.sub.2] modulates urine concentration by acting at E[P.sub.1] receptors, not in the collecting duct, but within the hypothalamus to promote AVP synthesis in response to acute WD. vasopressin; urine concentration; prostaglandin [E.sub.2]; E[P.sub.1] receptor

Vasopressin and vasopressin antagonists are finding expanded use in mouse models of disease and in clinical medicine. To provide further insight into the physiological role of V1a and V2 vasopressin receptors in the human and mouse kidney, intrarenal localization of the receptors mRNA was determined by in situ hybridization. V2-receptor mRNA was predominantly expressed in the medulla, whereas mRNA for Vla receptors predominated in the cortex. The segmental localization of vasopressin-receptor mRNAs was determined using simultaneous in situ hybridization and immunohistochemistry for segment-specific markers, including aquaporin-2, Dolichos biflorus agglutinin, epithelial Na channels, Tamm Horsfall glycoprotein, and thiazide-sensitive [Na.sup.-]-[Cl.sup.-] cotransporter. Notably, V1a receptor expression was exclusively expressed in V-ATPase/anion exchanger-1-labeled alpha-intercalated cells of the medullary collecting duct in both mouse and human kidney. In cortical collecting ducts, V1a mRNA was more widespread and detected in both principal and intercalated cells. V2-receptor mRNA is diffusely expressed along the collecting ducts in both mouse and human kidney, with higher expression levels in the medulla. These results demonstrate heterogenous axial expression of both V1a and V2 vasopressin receptors along the human and mouse collecting duct. The restricted expression of V1a-receptor mRNA in intercalated cells suggests a role for this receptor in acid-base balance. These findings further suggest distinct regulation of renal transport function by AVP through V1a and V2 receptors in the cortex vs. the medulla. in situ hybridization; vasopressin receptors; intercalated cell

Genetic mouse models provide a unique opportunity to investigate gene function in the natural course of the disease. Although diabetic nephropathy (DN) in models of type II diabetes has been well characterized, diabetic renal disease in hypoinsulinemic diabetic mice is still incompletely understood. Here, we characterized renal changes in the [pdx1.sup.PB]-HNF6 transgenic mouse that exhibits [beta]-cell dysfunction and nonobese hypoinsulinemic diabetes. Male transgenic mice developed hyperglycemia by the age of 7 wk and survived for over 1 yr without insulin treatment. Diabetes ensued earlier and progressed more severely in the HNF6 males than the females. The HNF6 males exhibited albuminuria as early as 10 wk of age, and the urinary albumin excretion increased with age, exceeding 150 [micro]g/24 h at 11 mo of age. Diabetic males developed renal hypertrophy after 7 wk of age, whereas glomerular hyperfiltration was not observed in the mice. Hypertension and hyperlipidemia were not observed in the diabetic mice. Histological analysis of the HNF6 kidneys displayed diabetic glomerular changes, including glomerular enlargement, diffuse mesangial proliferation and matrix expansion, thickened glomerular basement membrane, and arteriolar hyalinosis. Mesangial matrix accumulation increased with age, resulting in nodular lesions by 44 wk of age. Immunohistochemistry showed accumulation of type IV collagen and TGF-[beta]1 in the mesangial area. No significant immune complex deposition was observed in the HNF6 glomeruli. Thus the HNF6 mouse exhibits diabetic renal changes that parallel the early phase of human DN. The model should facilitate studies of genetic and environmental factors that may affect DN in hypoinsulinemic diabetes. animal model; diabetic renal disease; hepatocyte nuclear factor-6; transgenic mice

Abstract: In experimental glomerulonephritis, inhibition of renal prostaglandin (PG) synthesis by nonsteroidal-anti-inflammatory drugs (NSAIDs) moderates proteinuria, yet can induce harmful effects on renal blood flow and [Na.sup.+]-[K.sup.+]-water balance thereby implicating [...]

Functional and biochemical data have suggested a role for the cytochrome P450 arachidonate monooxygenases in the pathophysiology of hypertension, a leading cause of cardiovascular, cerebral, and renal morbidity and mortality. [...]

Liver X receptors (LXRs), including LXR[alpha] and LXR[beta], are intracellular sterol sensors that regulate expression of genes controlling fatty acid and cholesterol absorption, excretion, catabolism, and cellular efflux. Because the kidney plays an important role in lipid metabolism and dyslipidemia accelerates renal damage, we investigated the effect of TO-901317, an LXR agonist, on the gene expression profile in mouse kidney. Treatment of C57 B1/6 mice with TO-901317 (3 mg*[kg.sup.1]*[day.sup.-1]) for 3 days resulted in 51 transcripts that were significantly regulated in the kidney. Among them, the stearoyl-CoA desaturase-1 (SCD1) was upregulated most dramatically. Northern blot analysis revealed that SCD1 mRNA levels were markedly higher than that in control kidneys. Enhanced SCD1 expression by TO-901317 also resulted in increased fatty acid desaturation in the kidney. In control mice, constitutive renal SCD1 expression was low; however, TO-901317 treatment markedly increased SCD1 expression in the outer stripe of the outer medulla as assessed by both in situ hybridization and immunostain. Double-labeling studies further indicated that SCD1 mRNA was selectively expressed in proximal straight tubules negative for aquaporin-2 and Tamm-Horsfall protein. In vitro studies in cultured murine proximal tubule cells further demonstrated that LXR activation enhanced SCD1 transcription via increased sterol regulatory element binding protein-1. Taken together, these data suggest LXR activation of SCD1 expression may play an important role in regulating lipid metabolism and cell function in renal proximal straight tubules. gene expression; stearoyl-coenzyme A desaturase-1; sterol regulatory element binding protein-1; lipid metabolism

Thiazolidinediones (TZDs) are widely used to treat type 2 diabetes mellitus; however, their use is complicated by systemic fluid retention. Along the nephron, the pharmacological target of TZDs, peroxisome proliferator-activated receptor-[gamma] (PPAR[gamma], encoded by Pparg), is most abundant in the collecting duct. Here we show that mice treated with TZDs experience early weight gain from increased total body water. Weight gain was blocked by the collecting duct-specific diuretic amiloride and was also prevented by deletion of Pparg from the collecting duct, using Pparg [sup.flox/flox] mice. Deletion of collecting duct Pparg decreased renal Na[sup.+] avidity and increased plasma aldosterone. Treating cultured collecting ducts with TZDs increased amiloride-sensitive Na[sup.+] absorption and Scnn1g mRNA (encoding the epithelial Na[sup.+] channel ENaC[gamma]) expression through a PPAR[gamma]-dependent pathway. These studies identify Scnn1g as a PPAR[gamma] target gene in the collecting duct. Activation of this pathway mediates fluid retention associated with TZDs, and suggests amiloride might provide a specific therapy., Author(s): YouFei Guan [1, 2]; Chuanming Hao [1, 2]; Dae Ryong Cha [1, 2]; Reena Rao [1, 2]; Wendell Lu [1, 2]; Donald E Kohan [1, 3, 4]; Mark A [...]

Mice lacking a functional cyclooxygenase-2 (COX-2) gene develop abnormal kidneys that contain hypoplastic glomeruli and reduced proximal tubular mass, and they often die of renal failure. A comparison of kidneyspecific gene expression between wild-type and COX-2-deficient mice by cDNA microarrays revealed that although more than 500 mRNAs were differentially expressed between the two strains of mice depending on their ages, the genes encoding pre-pro-epidermal growth factor (pre-pro-EGF) and Tamm-Horsfall protein (THP)/uromodulin were aberrantly expressed in the kidneys of COX-2 -/mice at all stages of their development. Downregulation of EGF could potentially affect renal development, and THP/uromodulin gene has been implicated in abnormal kidney development and end-stage renal failure in humans. We assessed in detail mechanism of defective THP/uromodulin gene expression and its potential consequences in COX-2-deficient mice. Consistent with the microarray data, the steady-state levels of THP/uromodulin mRNA were severely reduced in the COX-2 -/- kidney. Furthermore, reduced expression of renal THP/uromodulin, as assessed by Western blot and immunohistological methods, was closely corroborated by a corresponding decline in the urinary secretion of THP/uromodulin in COX-2 -/- mice. Finally, we demonstrate that the bladders of COX-2 -/- mice, in contrast to those of the wild-type mice, are highly susceptible to colonization by uropathogenic Escherichia coli. prostaglandins; Escherichia coli

The use of LiCl in clinical psychiatry is routinely complicated by overt nephrogenic diabetes insipidus (NDI), the mechanism of which is incompletely understood. In vitro studies indicate that lithium can induce renal medullary interstitial cell cyclooxygenase 2 (COX2) protein expression via inhibition of glycogen synthase kinase-3[beta] (GSK-3[beta]). Both COX1 and COX2 are expressed in the kidney. Renal prostaglandins have been suggested to play an important role in lithium-induced polyuria. The present studies examined whether induction of the COX2 isoform contributes to LiCl-induced polyuria. Four days after initiation of lithium treatment in C57 BL/6J mice, urine volume increased in LiCl-treated mice by fourfold compared with controls (P < 0.0001) and was accompanied by decreased urine osmolality. This was temporally associated with increased renal COX2 protein expression and increased urinary [PGE.sub.2] excretion, whereas COX1 levels remained unchanged. COX2 inhibition significantly blunted lithium-induced polyuria (P < 0.0001) and reduced urinary [PGE.sub.2] levels. Lithium-associated polyuria was also seen in COX1-/- mice and was associated with increased urinary [PGE.sub.2]. COX2 inhibition completely prevented polyuria and [PGE.sub.2] excretion in COX1-/- mice, suggesting that COX2, but not COX1, plays a critical role in lithium-induced polyuria. Lithium also induced renal medullary COX2 protein expression in congenitally polyuric antidiuretic hormone (AHD)-deficient rats, demonstrating that lithiuminduced COX2 protein expression is not secondary to altered ADH levels or polyuria. Lithium also decreased renal medullary GSK-3[beta] activity, and this was temporally related to increased COX2 expression in the kidney from lithium-treated mice, consistent with a tonic in vivo suppression of COX2 expression by GSK-3 activity. In conclusion, these findings temporally link decreased GSK-3 activity to enhanced renal COX2 expression and COX2-derived urine [PGE.sub.2] excretion. Suppression of COX2-derived PGE2 blunts lithium-associated polyuria. prostaglandin E2; urine osmolality

Liver X receptor-[alpha] mediates cholesterol efflux in glomerular mesangial cells. Am J Physiol Renal Physiol 287: F886-F895, 2004. First published July 27, 2004; doi:10.1152/ajprenal.00123.2004.--Lipid-mediated injury plays an important role in the pathogenesis of many renal diseases including diabetic nephropathy. Liver X receptor-[alpha] (LXR[alpha]) is an intracellular sterol sensor that regulates expression of genes controlling cholesterol absorption, excretion, catabolism, and cellular efflux. The present study was aimed at examining the role of LXR[alpha] in cholesterol metabolism in glomerular mesangial cells. A 1,561-bp fragment of full-length rabbit LXR cDNA was cloned. The deduced protein sequence exhibited 92.4 and 89.2% identity to human and mouse LXR[alpha], respectively. Tissue distribution studies showed that rabbit LXR[alpha] was expressed in the liver, spleen, and kidney. In situ hybridization and RT-PCR assays further indicated that LXR[alpha] mRNA was widely expressed in the kidney and present in every nephron segment including the glomeruli. To determine intrarenal regulation of LXR[alpha], rabbits were treated with thiazolidinedione (TZD) peroxisome proliferator-activated receptor--[gamma] (PPAR[gamma]) agonists, which have been previously shown to enhance LXR[alpha] expression via PPAR[gamma] and increase cholesterol efflux in macrophages. The results showed that glomerular LXR[alpha] expression was markedly induced by TZDs. In cultured rabbit mesangial cells, LXR[alpha] mRNA and protein were detected by RT-PCR and immunoblotting. Treatment of mesangial cells with a specific LXR[alpha] agonist, TO-901317, significantly increased basal and apolipoprotein AI-mediated cholesterol efflux and markedly enhanced the promoter activity of an LXR[alpha] target gene, ATP-binding cassette transporter A1 (ABCA1). In conclusion, LXR[alpha] is expressed in renal glomeruli and functionally present in mesangial cells where its activation mediates cholesterol efflux via ABCA1. These data suggest that LXR[alpha] may be a potential therapeutic target for treating lipid-related renal glomerular disease. glomeruli; ATP-binding cassette transporter A1

Two nonradioactive methods for determining glomerular filtration rate (GFR) in conscious mice using FITC-labeled inulin (FITC-inulin) were evaluated. The first method measured GFR using clearance kinetics of plasma FITC-inulin after a single bolus injection. Based on a two-compartment model, estimated GFR was 236.69 [+ or -] 16.55 and 140.20 [+ or -] 22.27 [micro]l/min in male and female C57BL/6J mice, respectively. Total or 5/6 nephrectomy reduced inulin clearance to 0 or 32.80 [+ or -] 9.32 [micro]l/min, respectively. Conversely, diabetes mellitus induced by streptozotocin was associated with increased GFR. The other approach measured urinary inulin clearance using intraperitoneal microosmotic pumps to deliver FITC-inulin and metabolic cages to collect timed urine samples. This approach yielded similar GFR values of 211.11 [+ or -] 26.56 and 157.36 [+ or -] 20.02 [micro]l/min in male and female mice, respectively. These studies demonstrate the feasibility of repeated nonisotopic measurement of inulin clearance in conscious mice. hemodynamics; nephrectomy; diabetes mellitus; salts

[PGF.sub.2[alpha]] is one of the major prostanoids produced by the kidney. The cellular effects of [PGF.sub.2[alpha]] are mediated by a G protein-coupled transmembrane receptor designated the FP receptor. Both in situ hybridization and [beta]-galactosidase knocked into the endogenous FP locus were used to determine the cellular distribution of the mouse FP receptor. Specific labeling was detected in the kidney, ovary, and uterus. Abundant FP expression in ovarian follicles and uterus is consistent with previous reports of failed parturition in FP-/- mice. In the kidney, coexpression of the mFP mRNA with the thiazide-sensitive cotransporter defined its expression in the distal convoluted tubule (DCT). FP receptor was also present in aquaporin-2-positive cortical collecting ducts (CCD). No FP mRNA was detected in glomeruli, proximal tubules, or thick ascending limbs. Intrarehal expression of the FP receptor in the DCT and CCD suggests an important role for the FP receptor regulating water and solute transport in these segments of the nephron. dinoprost; nephron; natriuresis; water

The Cre/loxP transgenic system may be used to achieve temporally and/or spatially regulated gene deletion. The Mx1Cre mouse expresses Cre recombinase under control of the IFN-inducible Mx1 promoter. Mx1Cre mice were crossed with a reporter strain (ROSA26tm1Sor) in which [beta]-galactosidase activity is expressed only after Cre-mediated recombination to determine the cellular pattern of Cre-mediated genetic recombination in the kidney and other tissues. Widespread recombination was observed in vascular endothelium as well as in the liver and spleen. Recombination was restricted to subsets of stromal cells in uterus, duodenum, colon, aorta, and kidney. In the cortex, [chi]-galactosidase activity was detected in a subset of tubules and all glomerular cells, including endothelium, mesangium, and podocytes. No [chi]-galactosidase activity was detected in proximal tubules. Costaining of kidneys with segment-specific markers demonstrated induction of [chi]-galactosidase activity in collecting duct, with sporadic labeling of the thick ascending limb but no significant labeling of distal convoluted tubules. We conclude that Mx1-driven gene recombination is spatially as well as temporally restricted. The Mx1Cre transgene should prove a useful reagent to achieve temporally regulated recombination in endothelial, glomerular, and distal renal epithelia in mice. Cre recombinase; liver; spleen; interstitium; collecting duct; glomerulus