Mammalian cell nano structures visualized by cryo Hilbert differential contrast transmission electron microscopy

We applied the Hilbert differential contrast phase electron microscopy technique for the first time to mammalian cells, Ptk2 cells. Intracellular architectures such as the cytoskeletal network, membranous organelles, and mitochondria were observed without prior removal of cell membranes or extraction of soluble proteins. The attachment of mitochondria and membrane organelles with microtubules were observed. Microtubules were depolymerized by nocodazole treatment as expected. Thus, Hilbert differential contrast phase electron microscopy of vitrified cells is a nano-scale molecular imaging technique that opens up new vistas for exploring the supramolecular organization of the mammalian cell.

Structural analyses of O-glycan sugar chains on IgA1 hinge region using SELDI-TOFMS with various lectins

The aim of the study was to develop a simple and precise method for identifying glycosylation of the IgA hinge region using surface-enhanced laser desorption/ionization (SELDI)-TOFMS with a lectin-coupled ProteinChip array. Serum IgA was isolated using an anti-IgA antibody column. Following reduction, alkylation, and trypsin digestion, the IgA fragments were applied on the ProteinChip coupled with jacalin, peanut agglutinin (PNA), or Vilsa villosa lectin (VVL). The SELDI-TOFMS peaks corresponding to the fragments containing IgA1 hinge glycopeptides trapped by each lectin were compared. The jacalin-, PNA-, and VVL-immobilized ProteinChips detected 13, 4, and 2 peaks, respectively. One major peak was confirmed as a glycopeptide by MS/MS analysis. These results suggest that a lectin-immobilized ProteinChip assay can be used to simplify the procedures for the analyses of the O-glycans in IgA1 hinge. This method potentially makes it possible to identify a disease-specific glycoform by selecting the appropriate ligand-coupled ProteinChip array.

A severe diabetic nephropathy model with early development of nodule-like lesions induced by megsin overexpression in RAGE/iNOS transgenic mice

Many factors are involved in the pathogenesis of diabetic nephropathy. A single gene abnormality may be prerequisite but insufficient to the disease to manifest. It is therefore only when a second or sometimes a third damage is associated that the consequences of pathogenic phenotypes become evident. We generated the triple transgenic mice overexpressing megsin (a novel glomerular-specific serpin), a receptor for advanced glycation end products (RAGE), and inducible nitric oxide synthase (iNOS). Compared with the single- or two-gene transgenic mice, the triple transgenic mice developed, at an early age (16 weeks), severe albuminuria and renal damage with all of the characteristics of human diabetic nephropathy (i.e., glomerular hypertrophy, diffuse mesangial expansion, inflammatory cell infiltration, and interstitial fibrosis). Interestingly, 30-40% of glomeruli exhibit nodule-like lesions. Oxidative and carbonyl stress makers (pentosidine, N(epsilon)-carboxymethyllysine, and 8-hydroxy-deoxyguanosine) were significantly higher in the triple transgenic mice. The iNOS transgenic mice have a diabetes phenotype, the renal consequences of which are moot, and the superimposition of RAGE leads to more conspicuous manifestations. By additional overexpression of megsin, a gene known to be involved in mesangial proliferation and expansion, these local consequences become dramatically manifest and approximate those observed in human pathology. This multiple hit approach is of interest in consideration of the sequential events during development of diabetic nephropathy.

Activation of the JAK-STAT signaling pathway in the rat basilar artery after subarachnoid hemorrhage

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) is one of the most important signaling pathways transducing signals from the cell surface in response to cytokines. Subarachnoid hemorrhage (SAH) produces cytokines in the CSF. We investigated whether this signaling pathway is activated in the rat basilar artery after SAH by cytokines. In a rat single-hemorrhage model of SAH, basilar arteries and CSF were obtained until 7 days after SAH. The concentration of interleukin-6 (IL-6) in CSF was measured by ELISA. Western blot analysis with JAK1, phosphospecific-JAK1, STAT3, phosphospecific STAT3 at Tyr705 and Ser727, cyclooxygenase-2 (COX-2), and actin antibodies was performed in basilar artery. The expressions of STAT3, phosphospecific STAT3 at Tyr705 and Ser727, and COX-2 in basilar artery were examined by immunohistochemical studies. The concentration of IL-6 immediately increased after SAH and Western blot analysis revealed that JAK1 was phosphorylated within 2 h, accompanied by phosphorylation of STAT3 at Tyr705, extending to Ser727 at days 1-2. Immunohistochemistry revealed phosphorylation of STAT3 to occur in endothelial and smooth muscle cells of the basilar artery. In addition, intracisternal injection of IL-6 by itself significantly increased phosphorylation of STAT3 at Tyr705 and Ser727. Expression of COX-2 was also upregulated in endothelial cells of the basilar artery. These results indicate that SAH produces the proinflammatory cytokine IL-6 in the CSF, which activates the JAK-STAT signaling pathway in the basilar artery and induces transcription of immediate early genes.

Activation of JAK/STAT signalling in neurons following spinal cord injury in mice

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling pathway is one of the most important in transducing signals from the cell surface to the nucleus in response to cytokines. In the present study, we investigated chronological alteration and cellular location of JAK1, STAT3, phosphorylated (p)-Tyr1022/1023-JAK1, p-Tyr705-STAT3, and interleukin-6 (IL-6) following spinal cord injury (SCI) in mice. Western blot analysis showed JAK1 to be significantly phosphorylated at Tyr1022/1023 from 6 h after SCI, peaking at 12 h and gradually decreasing thereafter, accompanied by phosphorylation of STAT3 at Tyr705 with a similar time course. ELISA analysis showed the concentration of IL-6 in injured spinal cord to also significantly increase from 3 h after SCI, peaking at 12 h, then gradually decreasing. Immunohistochemistry revealed p-Tyr1022/1023-JAK1, p-Tyr705-STAT3, and IL-6 to be mainly expressed in neurons of the anterior horns at 12 h after SCI. Pretreatment with a JAK inhibitor, AG-490, suppressed phosphorylation of JAK1 and STAT3 at 12 h after SCI, reducing recovery of motor functions. These findings suggest that SCI at the acute stage produces IL-6 mainly in neurons of the injured spinal cord, which activates the JAK/STAT pathway, and that this pathway may be involved with neuronal response to SCI.

In a type 2 diabetic nephropathy rat model, the improvement of obesity by a low calorie diet reduces oxidative/carbonyl stress and prevents diabetic nephropathy

BACKGROUND

The present study has been undertaken to unravel the critical factors involved in the progression of diabetic nephropathy (DN).

METHODS

A unique type 2 diabetic rat model with a wide range of metabolic derangements and hypertension has been utilized, the spontaneously hypertensive/NIH-corpulent rat SHR/NDmcr-cp(cp/cp). It develops histologically evident glomerular injury and tubulointerstitial damage, including mesangial activation, podocyte injury, and inflammatory cell infiltration in the tubulointerstitium.

RESULTS

A low calorie diet for 22 weeks significantly improves obesity, proteinuria and renal morphological alterations. The correction of renal injury is independent of blood pressure control. Obesity correction, although partial, normalizes the renal content of pentosidine taken as a marker of oxidative stress and advanced glycation end products (AGEs). This occurs despite the fact that, in this model, improvement of glucose control and hyperlipidaemia is limited. Proteinuria and body weight are highly correlated with renal pentosidine content, while proteinuria and body weight are also correlated with each other. Diabetic renal injury is thus inhibited by a low calorie diet with an attendant reduction of oxidative stress and AGE formation, despite sustained hypertension.

CONCLUSION

The present findings suggest a direct role of obesity in the generation of a localized oxidative stress and AGE formation, directly responsible for DN.

Serpinopathy and endoplasmic reticulum stress

We have recently identified a novel human gene, megsin, which is a new serine protease inhibitor (serpin) predominantly expressed in the kidney. Our previous studies suggested a role of megsin in the pathogenesis of human renal diseases, but its exact biopathological significance remained unknown. During the analysis of experimental animals overexpressing the human megsin gene, we unexpectedly generated a "serpinopathy" model involving the kidney and pancreas and discovered a novel mechanism of renal injury, that is, cellular damage by endoplasmic reticulum (ER) stress caused by conformational disorder of protein tertiary structure within the ER. In vitro induction of ER stress may play a role in renal cell injury by various stimuli, but the involvement of ER stress in human renal disease remains elusive. Further research for ER structure and function may open new exciting prospects in the pathology of human renal diseases.

A novel scaffold protein, TANC, possibly a rat homolog of Drosophila rolling pebbles (rols), forms a multiprotein complex with various postsynaptic density proteins

We cloned from the rat brain a novel gene, tanc (GenBank Accession No. AB098072), which encoded a protein containing three tetratricopeptide repeats (TPRs), ten ankyrin repeats and a coiled-coil region, and is possibly a rat homolog of Drosophila rolling pebbles (rols). The tanc gene was expressed widely in the adult rat brain. Subcellular distribution, immunohistochemical study of the brain and immunocytochemical studies of cultured neuronal cells indicated the postsynaptic localization of TANC protein of 200 kDa. Pull-down experiments showed that TANC protein bound PSD-95, SAP97, and Homer via its C-terminal PDZ-binding motif, -ESNV, and fodrin via both its ankyrin repeats and the TPRs together with the coiled-coil domain. TANC also bound the alpha subunit of Ca2+/calmodulin-dependent protein kinase II. An immunoprecipitation study showed TANC association with various postsynaptic proteins, including guanylate kinase-associated protein (GKAP), alpha-internexin, and N-methyl-D-aspartate (NMDA)-type glutamate receptor 2B and AMPA-type glutamate receptor (GluR1) subunits. These results suggest that TANC protein may work as a postsynaptic scaffold component by forming a multiprotein complex with various postsynaptic density proteins.

Novel serpinopathy in rat kidney and pancreas induced by overexpression of megsin

The intracellular polymerization of abnormal serine protease inhibitors (serpins) results in liver or neuronal cell abnormalities recently identified as "serpinopathies." It was demonstrated in transgenic rats that overexpression of megsin, a recently discovered serpin located in the kidney, produces renal and pancreatic lesions characteristic of serpinopathies. Megsin expression is elevated in a variety of organs, including kidney and pancreas. Periodic acid-Schiff-positive, diastase-resistant intracellular inclusions develop only in the kidney and the pancreas. They correspond to electron-dense deposits, shown to contain megsin by immunohistochemistry and immunoelectron microscopy. In the kidney, inclusions are located mainly in the endoplasmic reticulum of glomerular epithelial, distal, and collecting duct cells, and are associated with massive proteinuria and an impaired renal function. In the pancreas, similar inclusions are found in the exocrine and Langerhans islet cells, where islet beta cells are reduced as a result of apoptosis. They are associated with diabetes with low insulin levels. The animals have an impaired growth and die within 10 wk. Rats that overexpress a mutant megsin, characterized by a deficient conformational transition activity, do not develop the serpinopathy, suggesting that some conformational flexibility of the serpin is required for the development of serpinopathy. This model of serpinopathy is the first to involve the kidney and the pancreas.

Modification of Endothelial NO Synthase Through Protein Phosphorylation After Forebrain Cerebral Ischemia/Reperfusion

BACKGROUND AND PURPOSE

Production of NO by endothelial NO synthase (eNOS) is thought to play a neuroprotective role after cerebral ischemia. The vascular endothelial growth factor (VEGF) contributes to activation of eNOS by Ca2+/calmodulin and also stimulates the protein kinase Akt, which directly phosphorylates eNOS on Ser1177 and increases enzyme activity. Although the expression of VEGF has been studied in ischemic stroke models, the activation of eNOS after cerebral ischemia has not been investigated. The purpose of the present study was to clarify molecular mechanisms underlying the regulation of eNOS activity through protein phosphorylation in postischemic processes.

METHODS

Sprague-Dawley rats were subjected to forebrain cerebral ischemia for 15 minutes with hypotension and reperfusion for up to 24 hours. Western blot analysis and ELISAs were used to study the temporal profiles of Akt, phospho-Akt at Ser437, eNOS, phospho-eNOS at Ser1177, and VEGF expression, respectively. Immunohistochemical studies were performed to examine the spatial expression patterns of phospho-Akt at Ser437 and phospho-eNOS at Ser1177.

RESULTS

Increase in phospho-Akt at Ser437 was observed transiently 0.5 to 2 hours after reperfusion, whereas elevation of phospho-eNOS at Ser1177 and VEGF expression was observed from 6 hours after reperfusion. Endothelial cells in the microvessels were the major source of eNOS phosphorylated at Ser1177 at the 12-hour time point.

CONCLUSIONS

Increase in Ser1177 phospho-eNOS occurs in endothelial cells of microvessels after ischemic episodes with temporal expression of VEGF, pointing to a contribution to the autoregulation of postischemic brain damage.

Appearance of erythrocyte-like globules in the mouse visceral yolk sac endodermal cells on embryonic day 12, with special reference to blood islands

The mouse visceral yolk sac (VYS) is widely known to play an important role as erythropoietic tissue during embryonic periods. Mouse VYS from embryonic days 9 to 12 was examined by light microscopy, electron microscopy and histochemical analysis with benzidine to detect the presence of hemoglobin with special reference to the development of VYS, the disappearance of the blood islands in VYS, and the appearance of a novel structure in the form of erythrocyte-like globules in VYS endodermal cells. The villous appearance of VYS became complicated by the development of VYS endodermal cells. The blood islands positive for the benzidine reaction were light microscopically detected on embryonic days 9, 10, and 11. They disappeared on embryonic day 12, however. Erythrocyte-like globules positive for the benzidine reaction were not observed in VYS endodermal cells on embryonic days 9, 10, and 11, but then appeared on embryonic day 12, by light and electron microscopy. Erythrocyte-like globules in VYS endodermal cells, which appear after the disappearance of blood islands in VYS, may participate in erythropoiesis during embryonic development.

Localization of translational components at the ultramicroscopic level at postsynaptic sites of the rat brain

We investigated the localization of components of translational machinery and their regulators in the postsynaptic region. We examined several components, especially those involved in translational regulation: components of (1) MAPK-Mnk-eIF4E, (2) PI3-kinase-PDK-Akt/PKB-FRAP/mTOR-PHAS/4EBP, (3) p70S6K-S6 ribosomal protein and (4) eEF2 kinase/CaMKIII-eEF2 pathways. Western blotting detected all the components examined in the synaptic fractions, and their differential localization to the synaptic subcompartments: initiation or elongation factors, except for eIF5, were detected predominantly in the dendritic lipid raft fraction, which contained ER marker proteins. In contrast, most of their regulatory kinases were distributed to both the postsynaptic density (PSD) and the dendritic lipid raft fractions, or enriched in the former fraction. Localization of eIF4E at synaptic sites was further examined immunohistochemically at the electron microscopic level. The eIF-4E-immunoreactivity was localized to the postsynaptic sites, especially to the microvesicle-like structures underneath the postsynaptic membrane in the spine, some of which were localized in close proximity to PSD. These results suggest that the postsynaptic local translational system, in at least four major regulatory pathways, is similar to those in the perinuclear one, and that it takes place, at least partly, immediately beneath the postsynaptic membrane. The results also suggest the presence of ER-associated type of translational machinery at the postsynaptic sites.

Huntingtin-interacting protein-1-related protein of rat (rHIP1R) is localized in the postsynaptic regions

We cloned a rHIP1R (GenBank Accession No., AB005052) encoding a Sla2/huntingtin-interacting protein (HIP1) family protein from a rat brain cDNA library. Localization of rHIP1R was investigated in the rat brain using an antibody specific to the HIP1R antibody. The rHIP1R protein was enriched in the synaptic plasma membrane fraction along with huntingtin, a synaptic protein and a causal protein for Huntington's disease. The electron microscopic examination revealed that HIP1R was localized at postsynaptic spines. Localization of HIP1R in the small vesicular structures in the spine, possible sites of vesicular transport of synaptic proteins, together with the structure-based analysis, suggested a role of HIP1R for vesicle trafficking through interaction with F-actin and working together with huntingtin and HIP1 at the synaptic sites.

A light and electron microscopic study of the mouse visceral yolk sac endodermal cells in the middle and late embryonic periods, showing the possibility of definitive erythropoiesis

Hematological studies have revealed the importance of the visceral yolk sac (VYS) in the primitive erythropoiesis of mouse embryos at an early stage before day 12. We examined the possibility of the occurrence of extra-embryonic erythropoiesis at a stage later than embryonic day 12 by light and electron microscopic analyses. Surprisingly, a novel structure in the form of erythrocyte-like globules was observed in the VYS endodermal cells. They were consistently present in the VYS endodermal cells from embryonic day 12 until day 18 (birth is day 19), by immunocytochemical and enzyme histochemical analyses. They were immuno-positive for mouse erythrocyte antibody and also positive for the benzidine reaction showing the presence of hemoglobin. The erythrocyte-like globules were shown to be the erythrocytes present in the cytoplasm. These results indicated that erythropoiesis in the VYS endodermal cells continues from the early embryonic stage, as primitive erythropoiesis, until the late stage.

Phosphorylation of neuronal nitric oxide synthase at Ser847 by CaM-KII in the hippocampus of rat brain after transient forebrain ischemia

The authors previously demonstrated that Ca2+/calmodulin (CaM)-dependent protein kinase IIalpha (CaM-KIIalpha) can phosphorylate neuronal nitric oxide synthase (nNOS) at Ser847 and attenuate NOS activity in neuronal cells. In the present study, they established that forebrain ischemia causes an increase in the phosphorylation of nNOS at Ser847 in the hippocampus. This nNOS phosphorylation appeared to be catalyzed by CaM-KII: (1) it correlated with the autophosphorylation of CaM-KIIalpha; (2) it was blocked by the CaM-KII inhibitor, KN-93; and (3) nNOS and CaM-KIIalpha were found to coexist in the hippocampus. Examination of the spatial relation between nNOS and CaM-KIIalpha in the brain revealed coexistence in the hippocampus but not in the cortex during reperfusion, with a concomitant increase in autophosphorylation of CaM-KIIalpha. The phosphorylation of nNOS at Ser847 probably takes place in nonpyramidal hippocampal neurons, which increased after 30 minutes of reperfusion in the hippocampus, whereas no significant increase was detected in the cortex. An intraventricular injection of KN-93 significantly decreased the phosphorylation of nNOS in the hippocampus. These results point to CaM-KII as a protein kinase, which by its colocalization may attenuate the activity of nNOS through its Ser847 phosphorylation, and may thus contribute to promotion of tolerance to postischemic damage in hippocampal neurons.

Identification of functions of peroxisome proliferator-activated receptor alpha in proximal tubules

Peroxisome proliferator-activated receptor alpha(PPARalpha) is a member of the steroid/nuclear receptor superfamily that is intensively expressed in the kidney, but its physiologic function is unknown. In this study, PPARalpha-null mice were used to help clarify the function. Starved PPARalpha-null mice were found to secrete significantly more quantities of urine albumin than starved wild-type mice. Furthermore, the appearance of giant lysosomes, marked accumulation of albumin, and an impaired ability concerning albumin digestion were found only in proximal tubules of the starved PPARalpha-null mice. These abnormalities were probably derived from ATP insufficiency as a result of the starvation-induced decline of carbohydrate metabolism and a lack of PPARalpha-dependent fatty acid metabolism. It is interesting that these abnormalities disappeared when glucose was administered. Taken together, these findings demonstrate important functions of PPARalpha in the proximal tubules, the dynamic regulation of the protein-degradation system through maintenance of ATP homeostasis, and emphasize the importance of the fatty acid metabolism in renal physiology.

Different accumulations of 3-ketoacyl-CoA thiolase precursor in peroxisomes of Chinese hamster ovary cells harboring a dysfunction in the PEX2 protein

The peroxisomal localization of 3-ketoacyl-CoA thiolase (hereafter referred to as thiolase) was characterized in five Chinese hamster ovary (CHO) mutant cell lines each harboring a dysfunction in the PEX2 protein. PT54 (Pex2pN100) cells carry a nonsense mutation that results in the PEX2 protein truncated at amino acid position 100. SK24 (Pex2pC258Y) cells carry a missense mutation resulting in the amino acid substitution of a cysteine residue by a tyrosine residue at amino acid position 258 of the PEX2 protein. The WSK24 (Pex2pC258Y/+wild) cell line is a stable transformant of SK24 (Pex2pC258Y) cells transfected with wild-type rat PEX2 cDNA. The SPT54 (Pex2pN100/+Pex2pC258Y) and WPT54 (Pex2pN100/+wild) cell lines are stable transformants of PT54 (Pex2pN100) cells transfected with the mutant PEX2 cDNA from SK24 (Pex2pC258Y) cells and wild-type rat PEX2 cDNA, respectively. In these cell lines, except PT54 (Pex2pN100), thiolase appeared to be localized in peroxisomes, as it is in the wild-type cells. When the molecular size of the enzyme was examined on SDS-polyacrylamide gel electrophoresis, the peroxisome-localized enzyme exhibited a larger precursor form in these mutant cells. The characterizations with salt wash, sodium carbonate extraction and proteinase K digestion indicated that the precursor forms of the enzyme were accumulated at different states in peroxisomes of these mutant cells. The dispositions on the peroxisomal membrane were further sustained by differential permeabilization using digitonin, followed by immunocytochemical fluorescence. These results suggest that PEX2 protein functions differently on two processes of the maturation and the disposition in the import pathway of thiolase.

Growth inhibition and differentiation of pancreatic cancer cell lines by PPAR gamma ligand troglitazone

INTRODUCTION

Ligand activation of peroxisome proliferator-activated receptor gamma (PPAR gamma) results in growth inhibition and differentiation of various cancer cells.

AIMS

We determined whether the PPAR gamma ligand, troglitazone, inhibits the growth of pancreatic cancer cells and clarified the underlying mechanisms with a special focus on restriction point control of the late G1 phase of the cell cycle.

METHODOLOGY

Nine pancreatic cancer cell lines were used to study a variety of troglitazone effects on cell growth by MTT assay, on cell cycle by flow cytometry, on cell cycle regulating factors of late G1 phase by Western and Northern blotting and CDK2 kinase assay, and on morphology by collagen gel culture and electron-microscopy.

RESULTS

Troglitazone showed a potent dose-response effect on the growth inhibition of six pancreatic cancer cell lines, which were suppressed to less than 50% of control at the concentration of 10 microM. The growth inhibition was linked to the G1 phase cell cycle arrest through the upregulation of p21 mRNA and protein expression simultaneously with the inhibition of CDK2 kinase activity and the hypophosphorylation of Rb protein. The upregulation of expression of p21 mRNA was mainly due to stabilization of mRNA. Troglitazone induced significant morphologic changes of duct structure with apoptotic cells in the lumen.

CONCLUSION

Troglitazone had growth inhibitory and differentiation induction effects on the pancreatic cancer cell lines through the upregulation of p21 expression, suggesting that ligand activation of PPAR gamma is a new molecular target for effective therapy against pancreatic cancer.

Temperature-sensitive phenotype of Chinese hamster ovary cells defective in PEX5 gene

SK32 mutant cells, which were isolated as peroxisome-deficient Chinese hamster ovary (CHO) cells by an advantage of a visible peroxisome form of green fluorescent protein (GFP), were found to suffer from a functional loss of PEX5 gene encoding for PTS1R. The sequence analysis of cDNA indicated that PEX5 gene encoded for the two isoforms composed of 603 amino acids (PTS1RS) and 640 amino acids (PTS1RL). The mutation changed glycine to arginine at amino acid position 343 of PTS1RL (corresponding to the position 306 of PTS1RS) in SK32 cells. The mutant cells exhibited a temperature-sensitive (TS) phenotype on the peroxisomal localizations of the recombinant GFP and urate oxidase appending a genuine peroxisome targeting signal 1 (PTS1), a tripeptide of Ser-Lys-Leu (SKL) at the C-terminus, but did not on that of catalase harboring a divergent PTS1, Lys-Ala-Asn-Leu (KANL) sequence. 3-ketoacyl-CoA thiolase (hereafter referred to as thiolase), which harbors an extension sequence (PTS2) at the N-terminus, never appeared to be affected on the peroxisomal localization in the mutant cells. When thiolase was examined on the molecular size in the mutant cells, the enzyme existed as the larger precursor form in the peroxisomes at 37 degrees C and a considerable part (almost half) was converted to the mature size at 30 degrees C. These results indicate that the amino acid substitution, Gly306Arg in PTS1RS and/or Gly343Arg in PTSRL, gives rise to TS phenotype on the peroxisomal translocation of PTS1 proteins and the maturation of PTS2 protein.

Role of peroxisome proliferator-activated receptor gamma and its ligands in non-neoplastic and neoplastic human urothelial cells

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-activated transcription factors and is expressed in several types of tissue. Although PPARgamma reportedly is expressed in normal urothelium, its function is unknown. We examined the expression of PPARgamma in normal urothelium and bladder cancer in an attempt to assess its functional role. Immunohistochemical staining revealed normal urothelium to express PPARgamma uniformly. All low-grade carcinomas were positive either diffusely or focally, whereas staining was primarily focal or absent in high-grade carcinomas. A nonneoplastic urothelial cell line (1T-1), a low-grade (RT4) carcinoma cell line, and two high-grade (T24 and 253J) carcinoma cell lines in culture expressed PPARgamma mRNA and protein. Luciferase assay indicated that PPARgamma was functional. PPARgamma ligands (15-deoxy-Delta(12,14)-prostaglandin J(2), troglitazone and pioglitazone) suppressed the growth of nonneoplastic and neoplastic urothelial cells in a dose-dependent manner. However, neoplastic cells were more resistant than were nonneoplastic cells. Failure to express PPARgamma or ineffective transcriptional activity may be some of the mechanisms responsible for resistance to the inhibitory action of PPARgamma ligands.

Peroxisomes in permanent and provisional kidneys. Phylogenic and ontogenic considerations

Peroxisomes in three forms of vertebrate kidney (pronephros, mesonephros, and metanephros), as permanent or provisional kidney, are summarized concerning their ultrastructure and developmental changes. Because the peroxisome is known to be diverse in mammalian metanephros, and species difference is its distinctive feature among cell organelles, information should be obtained on each kidney of each species. The ultrastructural and biochemical features of peroxisomes have at least been partly delineated in the metanephros and mesonephros, but nothing is known about the pronephros. Ultrastructural studies of the metanephric peroxisomes are present in mammals, birds, and reptiles, but information on their development is restricted to mammals and birds. As for the mesonephric peroxisomes, both ultrastructural and developmental data have been accumulating on mammals and amphibians, and ultrastructural information is present on fishes, but not on birds and reptiles. At present, studies on peroxisomes of provisional kidney have been restricted to mammalian mesonephros. The common features of renal peroxisomes previously examined are that they are spherical cell organelles with a single limiting membrane in ultrastructure, and are positive for catalase. Information on the ultrastructure and enzymes is not sufficient at present for comparing the ontogenesis of renal peroxisomes with their phylogenesis.

High serum IgG4 concentrations in patients with sclerosing pancreatitis

BACKGROUND

Sclerosing pancreatitis is a unique form of pancreatitis that is characterized by irregular narrowing of the main pancreatic duct, lymphoplasmacytic inflammation of the pancreas, and hypergammaglobulinemia and that responds to glucocorticoid treatment. Preliminary studies suggested that serum IgG4 concentrations are elevated in this disease but not in other diseases of the pancreas or biliary tract.

METHODS

We measured serum IgG4 concentrations using single radial immunodiffusion and an enzyme-linked immunosorbent assay in 20 patients with sclerosing pancreatitis, 20 age- and sex-matched normal subjects, and 154 patients with pancreatic cancer, ordinary chronic pancreatitis, primary biliary cirrhosis, primary sclerosing cholangitis, or Sjögren's syndrome. Serum concentrations of immune complexes and the IgG4 subclass of immune complexes were determined by means of an enzyme-linked immunosorbent assay with monoclonal rheumatoid factor.

RESULTS

The median serum IgG4 concentration in the patients with sclerosing pancreatitis was 663 mg per deciliter (5th and 95th percentiles, 136 and 1150), as compared with 51 mg per deciliter (5th and 95th percentiles, 15 and 128) in normal subjects (P<0.001). The serum IgG4 concentrations in the other groups of patients were similar to those in the normal subjects. In patients with sclerosing pancreatitis, serum concentrations of immune complexes and the IgG4 subclass of immune complexes were significantly higher before glucocorticoid therapy than after four weeks of such therapy. Glucocorticoid therapy induced clinical remissions and significantly decreased serum concentrations of IgG4, immune complexes, and the IgG4 subclass of immune complexes.

CONCLUSIONS

Patients with sclerosing pancreatitis have high serum IgG4 concentrations, providing a useful means of distinguishing this disorder from other diseases of the pancreas or biliary tract.

High serum IgG4 concentrations in patients with sclerosing pancreatitis

BACKGROUND

Sclerosing pancreatitis is a unique form of pancreatitis that is characterized by irregular narrowing of the main pancreatic duct, lymphoplasmacytic inflammation of the pancreas, and hypergammaglobulinemia and that responds to glucocorticoid treatment. Preliminary studies suggested that serum IgG4 concentrations are elevated in this disease but not in other diseases of the pancreas or biliary tract.

METHODS

We measured serum IgG4 concentrations using single radial immunodiffusion and an enzyme-linked immunosorbent assay in 20 patients with sclerosing pancreatitis, 20 age- and sex-matched normal subjects, and 154 patients with pancreatic cancer, ordinary chronic pancreatitis, primary biliary cirrhosis, primary sclerosing cholangitis, or Sjögren's syndrome. Serum concentrations of immune complexes and the IgG4 subclass of immune complexes were determined by means of an enzyme-linked immunosorbent assay with monoclonal rheumatoid factor.

RESULTS

The median serum IgG4 concentration in the patients with sclerosing pancreatitis was 663 mg per deciliter (5th and 95th percentiles, 136 and 1150), as compared with 51 mg per deciliter (5th and 95th percentiles, 15 and 128) in normal subjects (P<0.001). The serum IgG4 concentrations in the other groups of patients were similar to those in the normal subjects. In patients with sclerosing pancreatitis, serum concentrations of immune complexes and the IgG4 subclass of immune complexes were significantly higher before glucocorticoid therapy than after four weeks of such therapy. Glucocorticoid therapy induced clinical remissions and significantly decreased serum concentrations of IgG4, immune complexes, and the IgG4 subclass of immune complexes.

CONCLUSIONS

Patients with sclerosing pancreatitis have high serum IgG4 concentrations, providing a useful means of distinguishing this disorder from other diseases of the pancreas or biliary tract.