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Journal of Developmental Biology Mar 2023Nephrons are the functional units which comprise the kidney. Each nephron contains a number of physiologically unique populations of specialized epithelial cells that... (Review)
Review
Nephrons are the functional units which comprise the kidney. Each nephron contains a number of physiologically unique populations of specialized epithelial cells that are organized into discrete domains known as segments. The principles of nephron segment development have been the subject of many studies in recent years. Understanding the mechanisms of nephrogenesis has enormous potential to expand our knowledge about the basis of congenital anomalies of the kidney and urinary tract (CAKUT), and to contribute to ongoing regenerative medicine efforts aimed at identifying renal repair mechanisms and generating replacement kidney tissue. The study of the zebrafish embryonic kidney, or pronephros, provides many opportunities to identify the genes and signaling pathways that control nephron segment development. Here, we describe recent advances of nephron segment patterning and differentiation in the zebrafish, with a focus on distal segment formation.
PubMed: 36976103
DOI: 10.3390/jdb11010014 -
Journal of the American Society of... Mar 2021Galloway-Mowat syndrome (GAMOS) is characterized by neurodevelopmental defects and a progressive nephropathy, which typically manifests as steroid-resistant nephrotic...
BACKGROUND
Galloway-Mowat syndrome (GAMOS) is characterized by neurodevelopmental defects and a progressive nephropathy, which typically manifests as steroid-resistant nephrotic syndrome. The prognosis of GAMOS is poor, and the majority of children progress to renal failure. The discovery of monogenic causes of GAMOS has uncovered molecular pathways involved in the pathogenesis of disease.
METHODS
Homozygosity mapping, whole-exome sequencing, and linkage analysis were used to identify mutations in four families with a GAMOS-like phenotype, and high-throughput PCR technology was applied to 91 individuals with GAMOS and 816 individuals with isolated nephrotic syndrome. and studies determined the functional significance of the mutations identified.
RESULTS
Three biallelic variants of the transcriptional regulator were detected in six families with proteinuric kidney disease. Four families with a variant in the protein's zinc-finger (ZNF) domain have additional GAMOS-like features, including brain anomalies, cardiac defects, and skeletal defects. All variants destabilize the PRDM15 protein, and the ZNF variant additionally interferes with transcriptional activation. Morpholino oligonucleotide-mediated knockdown of Prdm15 in embryos disrupted pronephric development. Human wild-type RNA rescued the disruption, but the three variants did not. Finally, CRISPR-mediated knockout of in human podocytes led to dysregulation of several renal developmental genes.
CONCLUSIONS
Variants in can cause either isolated nephrotic syndrome or a GAMOS-type syndrome on an allelic basis. PRDM15 regulates multiple developmental kidney genes, and is likely to play an essential role in renal development in humans.
Topics: Amino Acid Sequence; Amino Acid Substitution; Animals; Cell Line; Child, Preschool; DNA-Binding Proteins; Female; Gene Expression Regulation, Developmental; Gene Knockdown Techniques; Gene Knockout Techniques; Hernia, Hiatal; High-Throughput Nucleotide Sequencing; Humans; Infant; Infant, Newborn; Male; Microcephaly; Models, Molecular; Mutation, Missense; Nephrosis; Nephrotic Syndrome; Podocytes; Polymorphism, Single Nucleotide; Pronephros; Protein Stability; Transcription Factors; Xenopus laevis; Zinc Fingers
PubMed: 33593823
DOI: 10.1681/ASN.2020040490 -
Methods in Cell Biology 2023Ciliated cells serve vital functions in the body ranging from mechano- and chemo-sensing to fluid propulsion. Specialized cells with bundles dozens to hundreds of motile...
Ciliated cells serve vital functions in the body ranging from mechano- and chemo-sensing to fluid propulsion. Specialized cells with bundles dozens to hundreds of motile cilia known as multiciliated cells (MCCs) are essential as well, where they direct fluid movement in locations such as the respiratory, central nervous and reproductive systems. Intriguingly, the appearance of MCCs has been noted in the kidney in several disease conditions, but knowledge about their contributions to the pathobiology of these states has remained a mystery. As the mechanisms contributing to ciliopathic diseases are not yet fully understood, animal models serve as valuable tools for studying cilia development and how alterations in ciliated cell function impacts disease progression. Like other vertebrates, the zebrafish, Danio rerio, has numerous ciliated tissues. Among these, the embryonic kidney (or pronephros) is comprised of both monociliated cells and MCCs and therefore provides a setting to investigate both ciliated cell fate choice and ciliogenesis. Considering the zebrafish nephron resembles the segmentation and function of human nephrons, the zebrafish provide a tractable model for studying conserved ciliogenesis pathways in vivo. In this chapter, we provide an overview of ciliated cells with a special focus on MCCs, and present a suite of methods that can be used to visualize ciliated cells and their features in the developing zebrafish. Further, these methods enable precise quantification of ciliated cell number and various cilia-related characteristics.
Topics: Animals; Humans; Zebrafish; Kidney; Zebrafish Proteins; Cilia; Cell Differentiation
PubMed: 36967138
DOI: 10.1016/bs.mcb.2022.12.001 -
Cells Apr 2022The anterior-posterior (AP) axis in chordates is regulated by a conserved set of genes and signaling pathways, including genes and retinoic acid (RA), which play...
The anterior-posterior (AP) axis in chordates is regulated by a conserved set of genes and signaling pathways, including genes and retinoic acid (RA), which play well-characterized roles in the organization of the chordate body plan. The intermediate mesoderm (IM), which gives rise to all vertebrate kidneys, is an example of a tissue that differentiates sequentially along this axis. Yet, the conservation of the spatiotemporal regulation of the IM across vertebrates remains poorly understood. In this study, we used a comparative developmental approach focusing on non-conventional model organisms, a chondrichthyan (catshark), a cyclostome (lamprey), and a cephalochordate (amphioxus), to assess the involvement of RA in the regulation of chordate and vertebrate pronephros formation. We report that the anterior expression boundary of early pronephric markers ( and ), positioned at the level of somite 6 in amniotes, is conserved in the catshark and the lamprey. Furthermore, RA, driving the expression of genes like in amniotes, regulates the anterior pronephros boundary in the catshark. We find no evidence for the involvement of this regulatory hierarchy in the AP positioning of the lamprey pronephros and the amphioxus pronephros homolog, Hatschek's nephridium. This suggests that despite the conservation of and expressions in chordate pronephros homologs, the responsiveness of the IM, and hence of pronephric genes, to RA- and -dependent regulation is a gnathostome novelty.
Topics: Animals; Chordata; Genes, Homeobox; Lampreys; Pronephros; Tretinoin; Vertebrates
PubMed: 35455988
DOI: 10.3390/cells11081304 -
Scientific Reports Oct 2023The nephron, functional unit of the vertebrate kidney, is specialized in metabolic wastes excretion and body fluids osmoregulation. Given the high evolutionary...
The nephron, functional unit of the vertebrate kidney, is specialized in metabolic wastes excretion and body fluids osmoregulation. Given the high evolutionary conservation of gene expression and segmentation patterning between mammalian and amphibian nephrons, the Xenopus laevis pronephric kidney offers a simplified model for studying nephrogenesis. The Lhx1 transcription factor plays several roles during embryogenesis, regulating target genes expression by forming multiprotein complexes with LIM binding protein 1 (Ldb1). However, few Lhx1-Ldb1 cofactors have been identified for kidney organogenesis. By tandem- affinity purification from kidney-induced Xenopus animal caps, we identified single-stranded DNA binding protein 2 (Ssbp2) interacts with the Ldb1-Lhx1 complex. Ssbp2 is expressed in the Xenopus pronephros, and knockdown prevents normal morphogenesis and differentiation of the glomus and the convoluted renal tubules. We demonstrate a role for a member of the Ssbp family in kidney organogenesis and provide evidence of a fundamental function for the Ldb1-Lhx1-Ssbp transcriptional complexes in embryonic development.
Topics: Animals; Xenopus laevis; LIM-Homeodomain Proteins; Gene Expression Regulation, Developmental; Transcription Factors; Kidney; Embryonic Development; Morphogenesis; Pronephros; Xenopus Proteins; Mammals
PubMed: 37794075
DOI: 10.1038/s41598-023-43662-1 -
Clonotypic IgH Response against Systemic Viral infection in Pronephros and Spleen of a Teleost Fish.Journal of Immunology (Baltimore, Md. :... Jun 2022Upon infection, B lymphocytes develop clonal responses. In teleost fish, which lack lymph nodes, the kinetics and location of B cell responses remain poorly...
Upon infection, B lymphocytes develop clonal responses. In teleost fish, which lack lymph nodes, the kinetics and location of B cell responses remain poorly characterized. Fish pronephros is the site of B cell differentiation and the main niche for persistence of plasma cells. In this study, we undertook the analysis of the rainbow trout IgHμ repertoire in this critical tissue for humoral adaptive immunity after primary immunization and boost with a rhabdovirus, the viral hemorrhagic septicemia virus (VHSV). We used a barcoded 5' RACE-cDNA sequencing approach to characterize modifications of the IgHμ repertoire, including VH usage in expressed V(D)J rearrangements, clonal diversity, and clonotype sharing between individual fish and treatments. In the pronephros, our approach quantified the clonotype frequency across the whole IgH repertoire (i.e., with all VH), measuring the frequency of Ag-responding clonotypes. Viral infection led to extensive modifications of the pronephros B cell repertoire, implicating several VH subgroups after primary infection. In contrast, only modest changes in repertoire persisted 5 mo later, including VHSV-specific public expansions. The IgM public response implicating IgHV1-18 and JH5, previously described in spleen, was confirmed in pronephros in all infected fish, strongly correlated to the response. However, the distribution of top clonotypes showed that pronephros and spleen B cells constitute distinct compartments with different IgH repertoires. Unexpectedly, after boost, the frequency of anti-VHSV clonotypes decreased both in pronephros and spleen, raising questions about B cell circulation. A better monitoring of B cell response kinetics in lymphoid tissues will be an essential step to understand B memory and plasmocyte formation mechanisms in fish.
Topics: Animals; Fish Diseases; Hemorrhagic Septicemia, Viral; Novirhabdovirus; Oncorhynchus mykiss; Pronephros; Spleen; Virus Diseases
PubMed: 35577368
DOI: 10.4049/jimmunol.2200088 -
BioRxiv : the Preprint Server For... Apr 2023The nephron, functional unit of the vertebrate kidney, is specialized in metabolic wastes excretion and body fluids osmoregulation. Given the high evolutionary...
The nephron, functional unit of the vertebrate kidney, is specialized in metabolic wastes excretion and body fluids osmoregulation. Given the high evolutionary conservation of gene expression and segmentation patterning between mammalian and amphibian nephrons, the pronephric kidney offers a simplified model for studying nephrogenesis. The Lhx1 transcription factor plays several roles during embryogenesis, regulating target genes expression by forming multiprotein complexes with LIM binding protein 1 (Ldb1). However, few Lhx1-Ldb1 cofactors have been identified for kidney organogenesis. By tandem-affinity purification from kidney-induced animal caps, we identified s ingle- s tranded DNA b inding p rotein 2 (Ssbp2) interacts with the Ldb1-Lhx1 complex. Ssbp2 is expressed in the pronephros, and knockdown prevents normal morphogenesis and differentiation of the glomus and the convoluted renal tubules. We demonstrate a role for a member of the Ssbp family in kidney organogenesis and provide evidence of a fundamental function for the Ldb1-Lhx1-Ssbp transcriptional complexes in embryonic development.
PubMed: 37090653
DOI: 10.1101/2023.04.15.537039 -
Kidney360 Apr 2022The renal glomerulus is a tuft of capillaries in Bowman's capsule and functions as a blood-filtration unit in the kidney. The unique glomerular capillary tuft structure...
BACKGROUND
The renal glomerulus is a tuft of capillaries in Bowman's capsule and functions as a blood-filtration unit in the kidney. The unique glomerular capillary tuft structure is relatively conserved through vertebrate species. However, the morphogenetic mechanism governing glomerular capillary tuft formation remains elusive.
METHODS
To clarify how glomerular capillaries develop, we analyzed glomerular capillary formation in the zebrafish pronephros by exploiting fluorescence-based bio-imaging technology.
RESULTS
During glomerular capillary formation in the zebrafish pronephros, endothelial cells initially sprouted from the dorsal aorta and formed the capillaries surrounding the bilateral glomerular primordia in response to podocyte progenitor-derived vascular endothelial growth factor-A. After formation, blood flow immediately occurred in the glomerular primordia-associated capillaries, while in the absence of blood flow, they were transformed into sheet-like structures enveloping the glomerular primordia. Subsequently, blood flow induced formation of Bowman's space at the lateral sides of the bilateral glomerular primordia. Concomitantly, podocyte progenitors enveloped their surrounding capillaries while moving toward and coalescing at the midline. These capillaries then underwent extensive expansion and remodeling to establish a functional glomerular capillary tuft. However, stopping blood flow inhibited the remodeling of bilateral glomerular primordia, which therefore remained unvascularized but covered by the vascular sheets.
CONCLUSIONS
We delineated the morphogenetic processes governing glomerular capillary tuft formation in the zebrafish pronephros and demonstrated crucial roles of blood flow in its formation. Blood flow maintains tubular structures of the capillaries surrounding the glomerular primordia and promotes glomerular incorporation of these vessels by inducing the remodeling of glomerular primordia.
Topics: Animals; Endothelial Cells; Kidney Glomerulus; Pronephros; Vascular Endothelial Growth Factor A; Zebrafish
PubMed: 35721616
DOI: 10.34067/KID.0005962021 -
Developmental Biology Jan 2022The corpuscles of Stannius (CS) represent a unique endocrine organ of teleostean fish that secrets stanniocalcin-1 (Stc1) to maintain calcium homeostasis. Appearing at...
The corpuscles of Stannius (CS) represent a unique endocrine organ of teleostean fish that secrets stanniocalcin-1 (Stc1) to maintain calcium homeostasis. Appearing at 20-25 somite stage in the distal zebrafish pronephros, stc1-expressing cells undergo apical constriction, and are subsequently extruded to form a distinct gland on top of the distal pronephric tubules at 50 h post fertilization (hpf). Several transcription factors (e.g. Hnf1b, Irx3b, Tbx2a/b) and signaling pathways (e.g. Notch) control CS development. We report now that Fgf signaling is required to commit tubular epithelial cells to differentiate into stc1-expressing CS cells. Inhibition of Fgf signaling by SU5402, dominant-negative Fgfr1, or depletion of fgf8a prevented CS formation and stc1 expression. Ablation experiments revealed that CS have the ability to partially regenerate via active cell migration involving extensive filopodia and lamellipodia formation. Activation of Wnt signaling curtailed stc1 expression, but had no effect on CS formation. Thus, our observations identify Fgf signaling as a crucial component of CS cell fate commitment.
Topics: Animals; Cell Differentiation; Endocrine Glands; Fibroblast Growth Factors; Glycoproteins; Pronephros; Wnt Signaling Pathway; Zebrafish; Zebrafish Proteins
PubMed: 34666023
DOI: 10.1016/j.ydbio.2021.10.005