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Scientific Reports Oct 2018The molecular events driving specification of the kidney have been well characterized. However, how the initial kidney field size is established, patterned, and...
The molecular events driving specification of the kidney have been well characterized. However, how the initial kidney field size is established, patterned, and proportioned is not well characterized. Lhx1 is a transcription factor expressed in pronephric progenitors and is required for specification of the kidney, but few Lhx1 interacting proteins or downstream targets have been identified. By tandem-affinity purification, we isolated FRY like transcriptional coactivator (Fryl), one of two paralogous genes, fryl and furry (fry), have been described in vertebrates. Both proteins were found to interact with the Ldb1-Lhx1 complex, but our studies focused on Lhx1/Fry functional roles, as they are expressed in overlapping domains. We found that Xenopus embryos depleted of fry exhibit loss of pronephric mesoderm, phenocopying the Lhx1-depleted animals. In addition, we demonstrated a synergism between Fry and Lhx1, identified candidate microRNAs regulated by the pair, and confirmed these microRNA clusters influence specification of the kidney. Therefore, our data shows that a constitutively-active Ldb1-Lhx1 complex interacts with a broadly expressed microRNA repressor, Fry, to establish the kidney field.
Topics: Animals; Body Patterning; Cell Line; Chromatography, Liquid; DNA-Binding Proteins; Gene Expression Regulation, Developmental; Gene Order; Genetic Vectors; Kidney; LIM-Homeodomain Proteins; MicroRNAs; Multiprotein Complexes; Organogenesis; Protein Binding; Repressor Proteins; Tandem Mass Spectrometry; Transcription Factors; Xenopus Proteins; Xenopus laevis
PubMed: 30375416
DOI: 10.1038/s41598-018-34038-x -
Biochemical and Biophysical Research... Aug 2004Vertebrates use two or three forms of kidney successively during development and the nephric duct is essential for this succession of kidney induction. While transcripts...
Vertebrates use two or three forms of kidney successively during development and the nephric duct is essential for this succession of kidney induction. While transcripts of many Wnt ligands and Wnt receptor Frizzled genes have been localized in developing kidney, the relationship between Wnt signaling and nephric duct development remains unknown. This study investigated the role of Xenopus frizzled-8 (Xfz8) in pronephros development. Translational inhibition of Xfz8 caused a significant reduction in the staining of a duct-specific antibody, but did not affect the expression of early pronephric maker genes in the duct region. Defects in pronephric tubule branching were also observed following inhibition of Xfz8. Histological analysis revealed that the Xfz8-inhibited cells failed to form a normal epithelium structure. These results suggest that Xfz8 is involved in the process of normal epithelium formation in the developing pronephric duct and tubules after specification.
Topics: Animals; Biomarkers; Female; Immunohistochemistry; In Situ Hybridization; Kidney; Morphogenesis; Protein Biosynthesis; Proto-Oncogene Proteins; Receptors, Cell Surface; Signal Transduction; Wnt Proteins; Xenopus Proteins; Xenopus laevis
PubMed: 15358202
DOI: 10.1016/j.bbrc.2004.06.166 -
Pediatric Nephrology (Berlin, Germany) Sep 2011Kidney development is a multi-step process where undifferentiated mesenchyme is converted into a highly complex organ through several inductive events. The general... (Review)
Review
Kidney development is a multi-step process where undifferentiated mesenchyme is converted into a highly complex organ through several inductive events. The general principles regulating these events have been under intense investigation and despite extensive progress, many open questions remain. While the metanephric kidneys of mouse and rat have served as the primary model, other organisms also significantly contribute to the field. In particular, the more primitive pronephric kidney has emerged as an alternative model due to its simplicity and experimental accessibility. Many aspects of nephron development such as the patterning along its proximo-distal axis are evolutionarily conserved and are therefore directly applicable to higher vertebrates. This review will focus on the current understanding of pronephros development in Xenopus. It summarizes how signaling, transcriptional regulation, as well as post-transcriptional mechanisms contribute to the differentiation of renal epithelial cells. The data show that even in the simple pronephros the mechanisms regulating kidney organogenesis are highly complex. It also illustrates that a multifaceted analysis embracing modern genome-wide approaches combined with single gene analysis will be required to fully understand all the intricacies.
Topics: Animals; Developmental Biology; Epithelial Cells; Gene Expression Regulation, Developmental; History, 20th Century; History, 21st Century; Organogenesis; Pronephros; Signal Transduction; Xenopus
PubMed: 21499947
DOI: 10.1007/s00467-011-1881-2 -
Developmental Dynamics : An Official... May 2005The kidney plays a critical role in regulating the composition of the blood, including pH. The major buffer regulating pH of the blood is bicarbonate. Bicarbonate is...
The kidney plays a critical role in regulating the composition of the blood, including pH. The major buffer regulating pH of the blood is bicarbonate. Bicarbonate is freely filtered through the glomerulus and must be recovered from the primary filtrate to maintain appropriate buffering capacity and blood pH. In this report, the expression of carbonic anhydrase type 2 within the late distal segment of pronephroi is described. This expression precisely overlaps that of the sodium-bicarbonate transporter XNBC1. In mammalian kidneys, these two proteins collaborate in the transepithelial recovery of bicarbonate from the kidney filtrate. Coexpression of the genes encoding these proteins in Xenopus embryos indicates that pronephroi use the same recovery system and that this system is largely localized to the late portion of the pronephric distal segment. Not only do the simple pronephroi regulate water and solute balance, they also appear to regulate blood pH in a manner akin to that of the vastly more complex mammalian metanephric kidneys.
Topics: Acid-Base Equilibrium; Amino Acid Sequence; Animals; Carbonic Anhydrase II; Kidney Tubules, Distal; Molecular Sequence Data; Sodium-Bicarbonate Symporters; Xenopus laevis
PubMed: 15712278
DOI: 10.1002/dvdy.20225 -
Developmental Biology Dec 1990To determine if cell migration is involved in the formation of the pronephric duct in Xenopus, we used morphometry, ablation, and videomicroscopy of vitally stained...
To determine if cell migration is involved in the formation of the pronephric duct in Xenopus, we used morphometry, ablation, and videomicroscopy of vitally stained cells to study duct formation. In St 23-24 (Nieuwkoop and Faber, 1956) embryos, a ridge of cells forms caudal to the pronephric rudiment. The ridge lengthens at approximately the same rate as the embryonic trunk from St 23 to St 31. Ablation experiments demonstrated that the ridge constitutes the pronephric duct rudiment (PDR); when the ridge was ablated at St 23-24, little or no duct formation occurred, whereas a duct formed when the pronephric rudiment was ablated and the ridge left intact. Vital dye injections showed that the PDR forms from the intermediate mesoderm ventral to myotomes IV-VIII. From St 29/30 to St 33/34, the PDR actively elongates along the ventral edge of the myotomes as far as myotome XIV, where it joins the cloaca as the pronephric duct. Videomicroscopy of vitally stained cells showed that the PDR elongates throughout its length and does not incorporate additional cells from the mesoderm over which it elongates. The results strengthen the case for a common mode of pronephric duct formation among amphibian species.
Topics: Animals; Cell Movement; Coloring Agents; Female; Kidney; Male; Mesoderm; Video Recording; Xenopus laevis
PubMed: 2257968
DOI: 10.1016/0012-1606(90)90349-n -
Genome Biology 2008The pronephros, the simplest form of a vertebrate excretory organ, has recently become an important model of vertebrate kidney organogenesis. Here, we elucidated the... (Comparative Study)
Comparative Study
BACKGROUND
The pronephros, the simplest form of a vertebrate excretory organ, has recently become an important model of vertebrate kidney organogenesis. Here, we elucidated the nephron organization of the Xenopus pronephros and determined the similarities in segmentation with the metanephros, the adult kidney of mammals.
RESULTS
We performed large-scale gene expression mapping of terminal differentiation markers to identify gene expression patterns that define distinct domains of the pronephric kidney. We analyzed the expression of over 240 genes, which included members of the solute carrier, claudin, and aquaporin gene families, as well as selected ion channels. The obtained expression patterns were deposited in the searchable European Renal Genome Project Xenopus Gene Expression Database. We found that 112 genes exhibited highly regionalized expression patterns that were adequate to define the segmental organization of the pronephric nephron. Eight functionally distinct domains were discovered that shared significant analogies in gene expression with the mammalian metanephric nephron. We therefore propose a new nomenclature, which is in line with the mammalian one. The Xenopus pronephric nephron is composed of four basic domains: proximal tubule, intermediate tubule, distal tubule, and connecting tubule. Each tubule may be further subdivided into distinct segments. Finally, we also provide compelling evidence that the expression of key genes underlying inherited renal diseases in humans has been evolutionarily conserved down to the level of the pronephric kidney.
CONCLUSION
The present study validates the Xenopus pronephros as a genuine model that may be used to elucidate the molecular basis of nephron segmentation and human renal disease.
Topics: Adult; Animals; Biomarkers; Cell Differentiation; Chloride-Bicarbonate Antiporters; Gene Expression Regulation, Developmental; Humans; Kidney; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Xenopus Proteins; Xenopus laevis
PubMed: 18492243
DOI: 10.1186/gb-2008-9-5-r84 -
Veterinary Immunology and... Jun 1986Since the teleost pronephros is an important source of diverse immunocytes, suspensions of pronephric cells from young adult carp have been characterized. In freshly...
Since the teleost pronephros is an important source of diverse immunocytes, suspensions of pronephric cells from young adult carp have been characterized. In freshly prepared suspensions, adherent, spreading cells (macrophages?) constituted less than 3% of the total population. Granulocytes and lymphocytes were co-dominant (less than 80%) leucocyte types. Continuous Percoll density gradient centrifugation yielded discrete subpopulations with these rho values and cytological characteristics: Fraction I & II rho = 1.055-1.070 thrombocytes, monocytes, macrophages, and lymphocytes. Fraction III rho = 1.080-1.090 granulocytes, type 1. Fraction IV rho = 1.105-1.110 erythrocytes and granulocytes, type 2. Fraction V rho = 1.118-1.125 granulocytes, type 3. Fraction VI rho = 1.140-1.150 granulocytes, type 4. Granulocyte motility increased markedly over the first 24 hr in vitro, and was enhanced by components washed from intact yeast. The subtypes of granulocytes were distinguishable by not only the rho values, but also on the basis of cell size, ultra-structure of the granules, and their histochemical and phagocytic characteristics. After simultaneous in vivo injection of Bacillus megaterium (Gram + ve), Aeromonas hydrophila (Gram - ve) and Saccharomyces cerevisiae (yeast), individual pronephric leucocytes were found capable of phagocytosing all three types of particle. Granulocytes which had phagocytosed B. megaterium were slower than macrophages in their ability to kill the bacteria. Encounter with B. megaterium or S. cerevisiae in vitro elicited a clumping reaction which involved mostly the larger leucocytes [granulocytes]. Both adherent cells and non-adherent cells were phagocytic in vitro.
Topics: Animals; Carps; Cyprinidae; Female; Granulocytes; Kidney; Leukocytes; Lymphocytes; Male; Phagocytosis
PubMed: 3765337
DOI: 10.1016/0165-2427(86)90118-2 -
Journal of Embryology and Experimental... Jun 1981The axolotl pronephric duct rudiment is readily accessible to both SEM observation and surgical manipulation. The rudiment segregates from the dorsal part of the lateral...
The axolotl pronephric duct rudiment is readily accessible to both SEM observation and surgical manipulation. The rudiment segregates from the dorsal part of the lateral mesoderm and then extends caudally along the ventrolateral border of the segmenting comites, eventually contacting the cloacal wall. The marked thinning of the rudiment which accompanies this migration is paralleled by a corresponding reduction in cell number across the duct's diameter and by caudad translocation and elongation of vital dye marks applied to the duct mesoderm. Duct extension thus involves appreciable cell rearrangement. The morphology of duct mesoderm and its substratum (somite and lateral mesoderm) suggests that active locomotion of cells near its tip marshals the duct's caudad elongation. Filopodia and small focal areas of intercellular contact may mediate the adhesions between the cells which must be broken and reformed as the cells rearrange.
Topics: Ambystoma mexicanum; Animals; Cell Movement; Kidney; Mesoderm; Microscopy, Electron, Scanning; Morphogenesis
PubMed: 7310283
DOI: No ID Found -
Journal of Comparative Pathology Oct 1995The amphibian pronephros is fated to die during early development. Pronephric cells undergo apoptosis and their function is replaced by the mesonephros, which becomes...
The amphibian pronephros is fated to die during early development. Pronephric cells undergo apoptosis and their function is replaced by the mesonephros, which becomes the functional kidney of the adult frog. Tadpoles of the northern leopard frog, Rana pipiens, were inoculated with a Lucké tumour herpesvirus (LTV) preparation. Most of the animals developed typical Lucké renal carcinomas at metamorphosis. Fewer developed carcinomas of the pronephric cell type. A pronephric carcinoma, rescued from apoptosis by the herpesvirus, was harvested from a post-metamorphic frog. The tumour was judged to be pronephric by its anatomical location (in the anterior part of the body) and because both mesonephric kidneys were intact and tumour-free upon removal of the tumour mass. A tumour fragment was fixed for histological examination, which confirmed that the tissue was a renal carcinoma. A further fragment was subjected to short-term culture in order to produce metaphase cells for cytogenetical analysis. Based upon silverstained nucleolar organizing region numbers, 14 of 15 metaphase cells were estimated to have the diploid number (2N = 26) of chromosomes and a karyotype was constructed which did not appear to differ from that of normal cells. A single cell was estimated to be tetraploid (4N = 52). This is the first report of chromosomes of a pronephric Lucké carcinoma. LTV replicates only in tumour tissue maintained in the cold. Because the frog in this study had been maintained in the laboratory at 22 degrees C for about 10 months, no viruses would have been detectable with electron microscopy. However, the presence of Lucké herpesvirus DNA was detected in tumour homogenates by polymerase chain reaction amplification of a 1.2 kbp Hind III restriction fragment of the LTV DNA. The presence of LTV DNA provided assurance that the rescued pronephric tumour was indeed a Lucké carcinoma.
Topics: Animals; Apoptosis; Base Sequence; Chromosomes; Herpesviridae Infections; Herpesvirus 1, Ranid; Karyotyping; Kidney; Kidney Neoplasms; Larva; Mesonephros; Molecular Probes; Molecular Sequence Data; Polymerase Chain Reaction; Rana pipiens; Tumor Virus Infections
PubMed: 8592053
DOI: 10.1016/s0021-9975(05)80042-8 -
Development (Cambridge, England) Dec 1998The zebrafish pronephric kidney provides a simplified model of nephron development and epithelial cell differentiation which is amenable to genetic analysis. The...
The zebrafish pronephric kidney provides a simplified model of nephron development and epithelial cell differentiation which is amenable to genetic analysis. The pronephros consists of two nephrons with fused glomeruli and paired pronephric tubules and ducts. Nephron formation occurs after the differentiation of the pronephric duct with both the glomeruli and tubules being derived from a nephron primordium. Fluorescent dextran injection experiments demonstrate that vascularization of the zebrafish pronephros and the onset of glomerular filtration occurs between 40 and 48 hpf. We isolated fifteen recessive mutations that affect development of the pronephros. All have visible cysts in place of the pronephric tubule at 2-2.5 days of development. Mutants were grouped in three classes: (1) a group of twelve mutants with defects in body axis curvature and manifesting the most rapid and severe cyst formation involving the glomerulus, tubule and duct, (2) the fleer mutation with distended glomerular capillary loops and cystic tubules, and (3) the mutation pao pao tang with a normal glomerulus and cysts limited to the pronephric tubules. double bubble was analyzed as a representative of mutations that perturb the entire length of the pronephros and body axis curvature. Cyst formation begins in the glomerulus at 40 hpf at the time when glomerular filtration is established suggesting a defect associated with the onset of pronephric function. Basolateral membrane protein targeting in the pronephric duct epithelial cells is also severely affected, suggesting a failure in terminal epithelial cell differentiation and alterations in electrolyte transport. These studies reveal the similarity of normal pronephric development to kidney organogenesis in all vertebrates and allow for a genetic dissection of genes needed to establish the earliest renal function.
Topics: Animals; Crosses, Genetic; DNA-Binding Proteins; Embryo, Nonmammalian; Embryonic Induction; Female; Gene Expression Regulation, Developmental; Kidney; Kidney Glomerulus; Kidney Tubules; Male; Mutagenesis; Nephrons; PAX2 Transcription Factor; Phenotype; Transcription Factors; WT1 Proteins; Zebrafish; Zebrafish Proteins; Zinc Fingers
PubMed: 9806915
DOI: 10.1242/dev.125.23.4655