Cytoplasmic hybrids, by fusing fish erythrophores and normal rat kidney cells

1991 ◽  
Vol 49 ◽  
pp. 266-267
Author(s):  
K.R. Porter ◽  
K.L. Anderson
Keyword(s):  
Rat Kidney ◽  
Structural Features ◽  
Cell Type ◽  
Pigment Granules ◽  
Normal Rat ◽  
Cytoplasmic Hybrids ◽  
Pigment Aggregation ◽  
General Architecture

When cultured together in the presence of PEG, these cells fuse (M1,M3) and survive in vitro for several days. This offers an opportunity to explore the capacity of one cell type (highly organized structurally) to impose it's structural features on a relatively unorganized cell type (NRK). Also, with two cells differing in several respects, one can ask questions regarding a role of the cell center in the control of pigment aggregation and dispersion, as well as the capacity of one cell type to assemble pigment granules in the cytplasm of another.First, in observations on general architecture .the hybrids have numerous microtubules (M3), but not the organized array of thousands observed in the erythrophores (M2). Furthermore, the microtubules in the hybrid are randomly oriented essentially as they are in the NRK cell (M4). There is a tendency observed in the hybrids for the pigment granules to concentrate among the microtubules and the cistemae of the ER (M3). Thus far, however, we have not succeeded consistently with epinephrine to induce aggregation, or with caffeine, dispersion.

scholarly journals Revisiting the role of IRF3 in inflammation and immunity by conditional and specifically targeted gene ablation in mice

2018 ◽  
Vol 115 (20) ◽  
pp. 5253-5258 ◽  
Author(s):  
Hideyuki Yanai ◽  
Shiho Chiba ◽  
Sho Hangai ◽  
Kohei Kometani ◽  
Asuka Inoue ◽  
...  
Keyword(s):  
Immune Cell ◽  
Cell Types ◽  
Type I ◽  
Type I Ifn ◽  
Cell Type ◽  
Gene Ablation ◽  
Cell Type Specific

IFN regulatory factor 3 (IRF3) is a transcription regulator of cellular responses in many cell types that is known to be essential for innate immunity. To confirm IRF3’s broad role in immunity and to more fully discern its role in various cellular subsets, we engineered Irf3-floxed mice to allow for the cell type-specific ablation of Irf3. Analysis of these mice confirmed the general requirement of IRF3 for the evocation of type I IFN responses in vitro and in vivo. Furthermore, immune cell ontogeny and frequencies of immune cell types were unaffected when Irf3 was selectively inactivated in either T cells or B cells in the mice. Interestingly, in a model of lipopolysaccharide-induced septic shock, selective Irf3 deficiency in myeloid cells led to reduced levels of type I IFN in the sera and increased survival of these mice, indicating the myeloid-specific, pathogenic role of the Toll-like receptor 4–IRF3 type I IFN axis in this model of sepsis. Thus, Irf3-floxed mice can serve as useful tool for further exploring the cell type-specific functions of this transcription factor.

scholarly journals BTCI enhances guanylin-induced natriuresis and promotes renal glomerular and tubular effects

2008 ◽  
Vol 68 (1) ◽  
pp. 149-154 ◽  
Author(s):  
AF. Carvalho ◽  
MS. Santos-Neto ◽  
HSA. Monteiro ◽  
SM. Freitas ◽  
L. Morhy ◽  
...  
Keyword(s):  
Filtration Rate ◽  
Rat Kidney ◽  
Structural Features ◽  
Urine Flow ◽  
Renal Metabolism ◽  
Chymotrypsin Inhibitor ◽  
Electrolyte Homeostasis ◽  
Perfused Rat Kidney ◽  
First Time

Guanylin and uroguanylin are small cysteine-rich peptides involved in the regulation of fluid and electrolyte homeostasis through binding and activation of guanylyl cyclases signaling molecules expressed in intestine and kidney. Guanylin is less potent than uroguanylin as a natriuretic agent and is degraded in vitro by chymotrypsin due to unique structural features in the bioactive moiety of the peptide. Thus, the aim of this study was to verify whether or not guanylin is degraded by chymotrypsin-like proteases present in the kidney brush-border membranes. The isolated perfused rat kidney assay was used in this regard. Guanylin (0.2 µM) induced no changes in kidney function. However, when pretreated by the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI - 1.0 µM; guanylin - 0.2 µM) it promoted increases in urine flow (deltaUF of 0.25 ± 0.09 mL.g-1/min, P < 0.05) and Na+ excretion (% delta ENa+ of 18.20 ± 2.17, P < 0.05). BTCI (1.0 µM) also increased %ENa+ (from 22.8 ± 1.30 to 34.4 ± 3.48, P < 0.05, 90 minutes). Furthermore, BTCI (3.0 µM) induced increases in glomerular filtration rate (GFR; from 0.96 ± 0.02 to 1.28 0.02 mL.g-1/min, P < 0.05, 60 minutes). The present paper strongly suggests that chymotrypsin-like proteases play a role in renal metabolism of guanylin and describes for the first time renal effects induced by a member of the Bowman-Birk family of protease inhibitors.

scholarly journals Developmental axon regrowth and primary neuron sprouting utilize distinct actin elongation factors

2020 ◽  
Vol 219 (5) ◽  
Author(s):  
Shiri P. Yaniv ◽  
Hagar Meltzer ◽  
Idan Alyagor ◽  
Oren Schuldiner
Keyword(s):  
Neurite Growth ◽  
Growth Potential ◽  
Neuronal Regeneration ◽  
Cell Type ◽  
Elongation Factors ◽  
Dynamic Expression ◽  
Unique System

Intrinsic neurite growth potential is a key determinant of neuronal regeneration efficiency following injury. The stereotypical remodeling of Drosophila γ-neurons includes developmental regrowth of pruned axons to form adult specific connections, thereby offering a unique system to uncover growth potential regulators. Motivated by the dynamic expression in remodeling γ-neurons, we focus here on the role of actin elongation factors as potential regulators of developmental axon regrowth. We found that regrowth in vivo requires the actin elongation factors Ena and profilin, but not the formins that are expressed in γ-neurons. In contrast, primary γ-neuron sprouting in vitro requires profilin and the formin DAAM, but not Ena. Furthermore, we demonstrate that DAAM can compensate for the loss of Ena in vivo. Similarly, DAAM mutants express invariably high levels of Ena in vitro. Thus, we show that different linear actin elongation factors function in distinct contexts even within the same cell type and that they can partially compensate for each other.

Nitric oxide enhancement of erythropoietin production in the isolated perfused rat kidney

1995 ◽  
Vol 269 (4) ◽  
pp. C917-C922 ◽  
Author(s):  
K. Yoshioka ◽  
J. W. Fisher
Keyword(s):  
Nitric Oxide ◽  
Rat Kidney ◽  
Mrna Levels ◽  
Isolated Perfused Rat Kidney ◽  
Intracellular Cgmp ◽  
Perfused Rat Kidney ◽  
Arterial Po2

We have previously reported that nitric oxide (NO) and guanosine 3',5'-cyclic monophosphate (cGMP) may be involved in the regulation of erythropoietin (Epo) production in response to hypoxia both in vivo and in vitro (20). In the present studies, we have used the isolated perfused rat kidney to assess the role of NO in oxygen sensing and Epo production. When arterial PO2 was reduced from 100 mmHg (normoxemic) to 30 mmHg (hypoxemic) in the perfusate of this system, perfusate levels of Epo were significantly increased. This hypoxia-induced increase in Epo production was significantly decreased by the addition of NG-nitro-L-arginine methyl ester (L-NAME; 1 mM) to the perfusates. Hypoxemic perfusion also produced a significant increase, and L-NAME significantly inhibited this increase, in intracellular cGMP levels in the kidney when compared with normoxemic perfused kidneys. Quantitative reverse transcription-polymerase chain reaction also revealed that hypoxemic perfusion produced significant increases in Epo mRNA levels in the kidney, which was blocked by L-NAME. Our findings further support an important role for the NO/cGMP system in hypoxic regulation of Epo production.

scholarly journals Substructure of the glomerular slit diaphragm in freeze-fractured normal rat kidney

1975 ◽  
Vol 65 (1) ◽  
pp. 233-236 ◽  
Author(s):  
MJ Karnovsky ◽  
GB Ryan
Keyword(s):  
Plasma Proteins ◽  
Plasma Membranes ◽  
Rat Kidney ◽  
Slit Diaphragm ◽  
Renal Glomerulus ◽  
Regular Array ◽  
Filtration Barrier ◽  
Normal Rat ◽  
Cross Bridges

In the renal glomerulus, the narrow slits between adjacent epithelial podocytes are bridged by a diaphragm (2, 8, 11). In rat and mouse kidneys fixed by perfusion with tannic acid and glutaraldehyde (TAG), it has recently been discovered that this diaphragm has a highly ordered, isoporous substructure (9). It consists of a regular array of alternating cross bridges extending from the podocyte plasma membranes to a centrally running filament. This zipperlike pattern results in two rows of rectangular pores, approximately 40 X 140 A in cross section, dimensions consistent with the proposed role of the diaphragm as an important filtration barrier to plasma proteins (6). In the present study, we found in freeze-cleaved and in freeze-etched normal rat glomeruli that the surface of the slit diaphragm has an appearance conforming to the pattern found in sectioned material.

Ischemia-induced cleavage of cadherins in NRK cells: evidence for a role of metalloproteinases

2005 ◽  
Vol 289 (2) ◽  
pp. F280-F288 ◽  
Author(s):  
Marisa D. Covington ◽  
Kayla J. Bayless ◽  
Robert C. Burghardt ◽  
George E. Davis ◽  
Alan R. Parrish
Keyword(s):  
Protein Expression ◽  
Glucose Transporter ◽  
Rat Kidney ◽  
Ischemia Reperfusion ◽  
Cell Number ◽  
Tissue Inhibitors Of Metalloproteinases ◽  
Glucose Transporter 1 ◽  
Normal Rat ◽  
E Cadherin

Although ischemia has been shown to disrupt cell adhesion, the underlying molecular mechanism is unknown. In these studies, we adapted a model of ischemia-reperfusion to normal rat kidney (NRK) cells, examined disruption of the cadherin/catenin complex, and identified a role for matrix metalloproteinases (MMPs) in ischemia-induced cleavage of cadherins. In NRK cells, ischemia was induced by applying a thin layer of PBS solution supplemented with calcium and magnesium and a layer of mineral oil, which restricts exposure to oxygen. NRK cells exhibited extracellular 80-kDa and intracellular 40-kDa E-cadherin fragments after 4 h of ischemia, and at 6 h the expression of full-length E-cadherin decreased. While no fragments of N-cadherin, α-catenin, and γ-catenin were observed at any time point, the detectable levels of these proteins decreased during ischemia. Ischemia was detected by an increase in pimonidazole adducts, as well as an increase in glucose transporter-1 protein expression. Ischemia did not decrease cell number, but there was a decrease in ATP levels. In addition, there was no evidence of cleaved caspase 3 or 9 during 6 h of ischemia. The MMP inhibitors GM-6001 and TAPI-O inhibited cleavage and/or loss of E- and N-cadherin protein expression. Tissue inhibitors of metalloproteinases (TIMP)-3 and to a lesser extent TIMP-2, but not TIMP-1, inhibit ischemic cleavage and/or loss of E- and N-cadherin. These results demonstrate that ischemia induces a selective metalloproteinase-dependent cleavage of E-cadherin and decrease in N-cadherin that are associated with a disruption of junctional contacts.

Retention of fetuin-A in renal tubular lumen protects the kidney from nephrocalcinosis in rats

2013 ◽  
Vol 304 (6) ◽  
pp. F751-F760 ◽  
Author(s):  
Isao Matsui ◽  
Takayuki Hamano ◽  
Satoshi Mikami ◽  
Kazunori Inoue ◽  
Akihiro Shimomura ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Proximal Tubules ◽  
Fetuin A ◽  
Receptor Associated Protein ◽  
Tubular Lumen ◽  
Proximal Tubular ◽  
Normal Rat ◽  
Natural Inhibitor ◽  
Renal Tubular

The serum glycoprotein fetuin-A is an important inhibitor of extraosseous calcification. The importance of fetuin-A has been confirmed in fetuin-A null mice, which develop widespread extraosseous calcification including the kidney. However, the mechanism how fetuin-A protects kidneys from nephrocalcinosis remains uncertain. Here, we demonstrate that intratubular fetuin-A plays a role in the prevention of nephrocalcinosis in the proximal tubules. Although normal rat kidney did not express mRNA for fetuin-A, we found punctate immunohistochemical staining of fetuin-A mainly in the S1 segment of the proximal tubules. The staining pattern suggested that fetuin-A passed through the slit diaphragm, traveled in the proximal tubular lumen, and was introduced into proximal tubular cells by megalin-mediated endocytosis. To test this hypothesis, we inhibited the function of megalin by intravenous injection of histidine-tagged soluble receptor-associated protein (His-sRAP), a megalin inhibitor. His-sRAP injection diminished fetuin-A staining in the proximal tubules and led to urinary excretion of fetuin-A. We further analyzed the role of fetuin-A in nephrocalcinosis. Continuous injection of parathyroid hormone (PTH) 1–34 induced nephrocalcinosis mainly in the proximal tubules in rats. His-sRAP retained fetuin-A in renal tubular lumen and thereby protected the kidneys of PTH-treated rats from calcification. Our findings suggest that tubular luminal fetuin-A works as a natural inhibitor against calcification in the proximal tubules under PTH-loaded condition.

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