| 1. |
- Beltcheva, O, et al.
(författare)
-
Sp1 specifically binds to an evolutionarily conserved DNA segment within a region necessary for podocyte-specific expression of nephrin
- 2010
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 114:1, s. E15-E22
-
Tidskriftsartikel (refereegranskat)abstract
- We have analyzed a conserved 237-bp segment located in a 1.9-kb upstream region of the nephrin gene, previously shown to contain kidney specific enhancer element(s). Electromobility shift assay was used to identify a 20-nucleotide region specifically recognized and bound by protein factors in nuclear extracts from immortalized podocyte and human embryonic kidney cell lines. The region was further narrowed down by competition assays to a stretch of 6 consecutive guanines, which are conserved at this location in multiple species. Introduction of mutations in this sequence abolished all protein binding activity whereas mutations in the flanking nucleotides did not. By means of gel supershift and chromatin immunoprecipitation assays we have shown that the protein factor from podocyte nuclear extracts able to recognize and bind the target sequence is the Sp1 zinc-finger protein.
|
|
| 2. |
- Betsholtz, C, et al.
(författare)
-
The glomerular transcriptome and proteome
- 2007
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 106:2, s. E32-E36
-
Tidskriftsartikel (refereegranskat)abstract
- Histopathology provides the current basis for classification and diagnosis of glomerular disorders. Molecular profiling methods, such as microarray analysis of mRNA expression, have rapidly emerged over the past years and are now applicable to minute amounts of tissue material, such as glomeruli from embryos or adult experimental animals, or from human renal needle biopsies. This review summarizes current efforts aiming at the determination of the glomerular transcriptome and proteome during development, in the healthy adult, and in disease. These studies are encouraging and show that comprehensive molecular profiling of the kidney glomerulus will most likely provide significant new insights into the normal structure and function of the glomerular filter, the molecular mechanisms of glomerular development, the diagnosis and classification of glomerular disease, and the pathogenic mechanisms underlying the stepwise breakdown of glomerular filter function that accompanies several common systemic disorders.
|
|
| 3. |
- Dunér, Fredrik, et al.
(författare)
-
Permeability, ultrastructural changes, and distribution of novel proteins in the glomerular barrier in early puromycin aminonucleoside nephrosis.
- 2010
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 116:2
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: It is still unclear what happens in the glomerulus when proteinuria starts. Using puromycin aminonucleoside nephrosis (PAN) rats, we studied early ultrastructural and permeability changes in relation to the expression of the podocyte-associated molecules nephrin, α-actinin, dendrin, and plekhh2, the last two of which were only recently discovered in podocytes. METHODS: Using immune stainings, semiquantitative measurement was performed under the electron microscope. Permeability was assessed using isolated kidney perfusion with tracers. Possible effects of ACE inhibition were tested. RESULTS: By day 2, some patchy foot process effacement, but no proteinuria, appeared. The amount of nephrin was reduced in both diseased and normal areas. The other proteins showed few changes, which were limited to diseased areas. By day 4, foot process effacement was complete and proteinuria appeared in parallel with signs of size barrier damage. Nephrin decreased further, while dendrin and plekhh2 also decreased but α-actinin remained unchanged. ACE inhibition had no significant protective effect. CONCLUSIONS: PAN glomeruli already showed significant pathology by day 4, despite relatively mild proteinuria. This was preceded by altered nephrin expression, supporting its pivotal role in podocyte morphology. The novel proteins dendrin and plekhh2 were both reduced, suggesting roles in PAN, whereas α-actinin was unchanged.
|
|
| 4. |
- Heikkila, P, et al.
(författare)
-
Animal models of Alport syndrome: advancing the prospects for effective human gene therapy
- 2000
-
Ingår i: Experimental nephrology. - : S. Karger AG. - 1018-7782 .- 1660-2129. ; 8:1, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- Several animal models for Alport syndrome have been described. These are available for studies on the pathogenetic mechanisms of the disease, as well as for the development of new technologies for gene therapy in this progressive hereditary kidney disease. This review summarizes current knowledge on the molecular basis of Alport syndrome, and on the animal models which all remarkably well resemble the human disease. Recent work aimed at the development of gene therapy, including hurdles and progress are discussed.
|
|
| 5. |
- Johansson, Martin
(författare)
-
Tubular regeneration: when can the kidney regenerate from injury and what turns failure into success?
- 2014
-
Ingår i: Nephron. Experimental Nephrology. - : S. Karger AG. - 1660-2129. ; 126:2, s. 76-81
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The most common intrarenal cause for acute kidney injury/renal failure is tubular damage. The kidney tubules are arranged as compartments of cellular mosaics to perform their functions, and at rest almost a fifth of the human ATP consumption is allotted to the reabsorption of substances from the filtrate, rendering especially the proximal tubules highly sensitive to oxygen and/or nutrient deprivation. Normally mitotically quiescent, the tubular epithelium shows a brisk regenerative response following injury if supportive care is offered, allowing functional restoration. Despite this, the cellular machinery behind the regenerative capacity is still not unequivocally defined. This is at odds with other epithelia such as those of the skin and intestine, where stem cells maintain a continuous flow of new cells from designated niches. Summary: This review discusses the classical concept of renal regeneration, i.e. stochastically surviving cells undergoing dedifferentiation (or epithelial-mesenchymal transition) followed by replenishment of the tubular epithelium. Furthermore however, this view has recently been challenged by the concept of organ-confined stem/progenitor cells, bone marrow-derived stem cells, or mesenchymal stem cells taking part in the regenerative events. Whereas results from animal models support the classical view, morphologically distinct cells have been demonstrated in human kidneys, requiring interpretation. This review presents some of the previous work and techniques and highlights issues that need to be reconciled. Key Messages: In adult humans, the kidney tubules contain scattered cells with a distinct set of markers and properties, such as increased robustness during tubular damage. These cells may be induced by injury or represent a resident progenitor cell pool. To date, animal studies using lineage-tracing methods argue for an inductive scenario. In humans, the situation is less clear and one might speculate that the cellular heterogeneity might reflect elements of cellular reprogramming to a progenitor-like state, perhaps by induction. Due to intense investigational efforts, however, a scientific consensus may soon be reached, which will benefit further research. © 2014 S. Karger AG, Basel.
|
|
| 6. |
- Khoshnoodi, J, et al.
(författare)
-
Unraveling the molecular make-up of the glomerular podocyte slit diaphragm
- 2001
-
Ingår i: Experimental nephrology. - : S. Karger AG. - 1018-7782 .- 1660-2129. ; 9:6, s. 355-359
-
Tidskriftsartikel (refereegranskat)abstract
- Recent discoveries in podocyte proteins involved in the renal filtration barrier have shed new light on the ultrastructure of the kidney filter and pathogenesis of proteinuria. The identification of nephrin, a component of the slit diaphragm, and the intracellular slit diaphragm associated proteins CD2AP and podocin has demonstrated the existence of proteins that directly contribute to a functional kidney filter. Mutations in the genes for these three proteins result in proteinuria and nephrotic syndrome, and these proteins are also likely to be involved more generally in the pathomechanisms of proteinuria. This new knowledge has been promoted particularly through the powerful methods of molecular genetics and molecular biology. In this minireview, we present the recent progress in research of the podocyte slit diaphragm.
|
|
| 7. |
- Kujala, M, et al.
(författare)
-
SLC26A6 and SLC26A7 anion exchangers have a distinct distribution in human kidney
- 2005
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 101:2, s. E50-E58
-
Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> The anion transporters SLC26A6 (PAT1) and SLC26A7, transporting at least chloride, oxalate, sulfate and bicarbonate, show a distinct expression and function in different mammalian species. They are expressed in kidney, but their exact localization in human kidney has not been studied. We therefore examined SLC26A6 and A7 expression in human kidneys. <i>Methods:</i> The localization of SLC26A6 and A7 in different segments of human nephrons was studied by RT-PCR and immunohistochemistry by comparing to the tubular markers PNRA, CD10, Tamm-Horsfall antigen, high molecular weight cytokeratin, CK7, AQP2 and H<sup>+</sup>V-ATPase. <i>Results:</i> In human kidney, SLC26A6 is expressed in distal segments of proximal tubules, parts of the thin and thick ascending limbs of Henle’s loops, macula densa, distal convoluted tubules and a subpopulation of intercalated cells of collecting ducts. SLC26A7 is expressed in extraglomerular mesangial cells and a subpopulation of intercalated cells of collecting ducts. <i>Conclusion:</i> Our results show that in human kidney SLC26A6 and A7 have a distinct, partially overlapping expression in distal segments of nephrons. The distribution partly differs from that found previously in rodent kidneys.
|
|
| 8. |
- Melin, Jan, et al.
(författare)
-
Ischemia-induced renal expression of hyaluronan and CD44 in diabetic rats.
- 2006
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 103:3
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: Unilateral renal ischemia during 30 min causes severe, non-reversible renal damage in diabetic (DM) rats, but not in nondiabetic rats. Hyaluronan (HA) is a glycosaminglycan involved in various forms of renal injury. We examined the role of HA and CD44, a major receptor for HA, in the development of postischemic renal injury in DM rats. METHODS: The left renal artery of streptozotocin diabetic Wistar rats was clamped for 30 min. The HA content in the kidneys was measured. A biotinylated HA-binding probe was used to localize HA. Inflammatory cells and other cells expressing CD44 were identified by immunohistochemistry. RESULTS: In ischemic DM kidneys the renal HA-content started to increase already after 24 h and significantly so after 1-8 weeks after ischemia/reperfusion (I/R). The relative water content of the kidneys increased in parallel. HA started to appear in the cortex of ischemic DM kidneys 1 week after I/R. In contrast, the non-DM ischemic kidneys showed no increase of HA and water content after 1-8 weeks after I/R. The tubular cells in the cortex and outer medulla demonstrated increased staining for CD44. In the same compartments the increased numbers of infiltrating inflammatory cells also expressed CD44. CONCLUSION: HA-accumulation in the renal cortex might contribute to the renal damage seen after transient ischemia in DM rats by promoting inflammation through interaction between HA and CD44 expressing inflammatory cells. Furthermore, HA accumulation may contribute to an interstitial renal edema.
|
|
| 9. |
- Xiao, ZJ, et al.
(författare)
-
Glomerular podocytes express type 1 adenylate cyclase: inactivation results in susceptibility to proteinuria
- 2011
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 118:3, s. E39-E48
-
Tidskriftsartikel (refereegranskat)abstract
- <i>Background/Aims:</i> The organization of actin cytoskeleton in podocyte foot processes plays a critical role in the maintenance of the glomerular filtration barrier. The cAMP pathway is an important regulator of the actin network assembly in cells. However, the role of the cAMP pathway in podocytes is not well understood. Type 1 adenylate cyclase (Adcy1), previously thought to be specific for neuronal tissue, is a member of the family of enzymes that catalyses the formation of cAMP. In this study, we characterized the expression and role of A<i>dcy1</i> in the kidney. <i>Methods:</i> Expression of Adcy1 was studied by RT-PCR, Northern blotting and in situ hybridization. The role of <i>Adcy1</i> in podocytes was investigated by analyzing <i>Adcy1</i> knockout mice (Adcy1–/–). <i>Results and Conclusion:</i> Adcy1 is expressed in the kidney specifically by podocytes. In the kidney, Adcy1 does not have a critical role in normal physiological functioning as kidney histology and function are normal in Adcy1–/– mice. However, albumin overload resulted in severe albuminuria in Adcy1–/– mice, whereas wild-type control mice showed only mild albumin leakage to urine. In conclusion, we have identified Adcy1 as a novel podocyte signaling protein that seems to have a role in compensatory physiological processes in the glomerulus.
|
|
| 10. |
- Xu, Xiangjun, et al.
(författare)
-
Expression of novel podocyte-associated proteins sult1b1 and ankrd25.
- 2011
-
Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 117:2, s. e39-46
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: Podocytes have a unique function in the renal ultrafiltration that is achieved by expressing proteins that are highly specific to podocytes. In this study, we identified two novel podocyte-associated proteins.METHODS: The expression of sult1b1 and ankrd25 in mouse tissues was studied by RT-PCR. The protein expression was studied by generating polyclonal antibodies that were used in Western blotting and immunohistochemistry.RESULTS: By RT-PCR we detected sult1b1 expression only in glomerular, liver and brain tissues. By immunohistochemistry, sult1b1 was detected in the kidney exclusively in the Golgi apparatus of the podocyte. No expression outside the glomerulus was observed in the kidney. The ankrd25 transcript was detected in most mouse tissues analyzed by RT-PCR. In the kidney, however, immunohistochemistry showed that this protein was expressed only by podocyte, mesangial, and smooth muscle cells. In podocytes, ankrd25 was localized to foot processes.CONCLUSIONS: Identification of these two novel glomerulus-associated proteins opens up possibilities to investigate their role in the renal filter physiology and diseases. We speculate that sult1b1 may be involved in the sulfonylation of podocyte protein podocalyxin, whereas ankrd25 may contribute to controlling actin dynamics in podocyte foot processes.
|
|
