1
|
Checkpoints and Immunity in Cancers: Role of GNG12. Pharmacol Res 2022; 180:106242. [DOI: 10.1016/j.phrs.2022.106242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/25/2022] [Accepted: 04/28/2022] [Indexed: 12/24/2022]
|
2
|
Doganli C, Nyengaard JR, Lykke-Hartmann K. Zebrafish Whole-Mount In Situ Hybridization Followed by Sectioning. Methods Mol Biol 2016; 1377:353-363. [PMID: 26695046 DOI: 10.1007/978-1-4939-3179-8_31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In situ hybridization is a powerful technique used for locating specific nucleic acid targets within morphologically preserved tissues and cell preparations. A labeled RNA or DNA probe hybridizes to its complementary mRNA or DNA sequence within a sample. Here, we describe RNA in situ hybridization protocol for whole-mount zebrafish embryos.
Collapse
Affiliation(s)
- Canan Doganli
- Smith Cardiovascular Research Institute, University of California, San Francisco, CA, 94158-9001, USA
| | - Jens Randel Nyengaard
- Stereology and Electron Microscopy Laboratory, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Hospital, Aarhus University, Aarhus C, Denmark
| | - Karin Lykke-Hartmann
- Department of Biomedicine and Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, Aarhus C, Denmark.
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C, Denmark.
| |
Collapse
|
3
|
Molecular and functional characterization of seven Na+/K+-ATPase β subunit paralogs in Senegalese sole (Solea senegalensis Kaup, 1858). Comp Biochem Physiol B Biochem Mol Biol 2015; 182:14-26. [DOI: 10.1016/j.cbpb.2014.11.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Revised: 11/24/2014] [Accepted: 11/29/2014] [Indexed: 11/22/2022]
|
4
|
Kabbani N, Nordman JC, Corgiat BA, Veltri DP, Shehu A, Seymour VA, Adams DJ. Are nicotinic acetylcholine receptors coupled to G proteins? Bioessays 2014; 35:1025-34. [PMID: 24185813 DOI: 10.1002/bies.201300082] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
It was, until recently, accepted that the two classes of acetylcholine (ACh) receptors are distinct in an important sense: muscarinic ACh receptors signal via heterotrimeric GTP binding proteins (G proteins), whereas nicotinic ACh receptors (nAChRs) open to allow flux of Na+, Ca2+, and K+ ions into the cell after activation. Here we present evidence of direct coupling between G proteins and nAChRs in neurons. Based on proteomic, biophysical, and functional evidence, we hypothesize that binding to G proteins modulates the activity and signaling of nAChRs in cells. It is important to note that while this hypothesis is new for the nAChR, it is consistent with known interactions between G proteins and structurally related ligand-gated ion channels. Therefore, it underscores an evolutionarily conserved metabotropic mechanism of G protein signaling via nAChR channels.
Collapse
|
5
|
Doğanli C, Oxvig C, Lykke-Hartmann K. Zebrafish as a novel model to assess Na+/K(+)-ATPase-related neurological disorders. Neurosci Biobehav Rev 2013; 37:2774-87. [PMID: 24091024 DOI: 10.1016/j.neubiorev.2013.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/08/2013] [Accepted: 09/23/2013] [Indexed: 11/26/2022]
Abstract
Modeling neurological disorders using zebrafish increases rapidly as this model system allows easy access to all developmental stages and imaging of pathological processes. A surprising degree of functional conservation has been demonstrated between human genes implicated in neurodegenerative diseases and their zebrafish orthologues. Zebrafish offers rapid high throughput screening of therapeutic compounds and live imaging of pathogenic mechanisms in vivo. Several recent zebrafish studies functionally assessed the role of the sodium-potassium pump (Na(+)/K(+)-ATPase). The Na(+)/K(+)-ATPase maintains the electrochemical gradients across the plasma membrane, essential for e.g. signaling, secondary active transport, glutamate re-uptake and neuron excitability in animal cells. Na(+)/K(+)-ATPase mutations are associated with neurological disorders, where mutations in the Na(+)/K(+)-ATPase α2 and α3 isoforms cause Familial hemiplegic migraine type 2 (FHM2) and Rapid-onset dystonia-parkinsonism (RDP)/Alternating hemiplegic childhood (AHC), respectively. In zebrafish, knock-down of Na(+)/K(+)-ATPase isoforms included skeletal and heart muscle defects, impaired embryonic motility, depolarized Rohon-beard neurons and abrupt brain ventricle development. In this review, we discuss zebrafish as a model to assess Na(+)/K(+)-ATPase isoform functions. Furthermore, studies investigating proteomic changes in both α2- and α3-isoform deficient embryos and their potential connections to the Na(+)/K(+)-ATPase functions will be discussed.
Collapse
Affiliation(s)
- Canan Doğanli
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Copenhagen, Denmark; Aarhus University, Department of Biomedicine, Ole Worms Allé 3, Building 1171, DK-8000 Aarhus, Denmark; Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10, Building 3135, DK-8000 Aarhus, Denmark
| | | | | |
Collapse
|
6
|
Jin J, Morse M, Frey C, Petko J, Levenson R. Expression of GPR177 (Wntless/Evi/Sprinter), a highly conserved Wnt-transport protein, in rat tissues, zebrafish embryos, and cultured human cells. Dev Dyn 2011; 239:2426-34. [PMID: 20652957 DOI: 10.1002/dvdy.22369] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
GPR177 is an evolutionarily conserved transmembrane protein necessary for Wnt protein secretion. Little is currently known, however, regarding expression of GPR177, especially in vertebrate species. We have developed an antiserum against GPR177, and used it to examine expression of GPR177 in human tissue culture cells, adult mouse, and rat tissues, as well as developing zebrafish embryos. In rodents, GPR177 is expressed in virtually all tissue types and brain regions examined. In zebrafish, GPR177 polypeptides are expressed throughout embryogenesis, and are detectable as early as 1 hr post-fertilization. In situ hybridization analysis reveals that gpr177 mRNA expression is prominent in embryonic zebrafish brain and ear. Structural studies suggest that GPR177 is modified by N-linked sugars, and that the protein contains an even number of transmembrane segments. The relatively ubiquitous expression of GPR177 suggests that this protein may serve to regulate Wnt secretion in a variety of embryonic and adult tissue types.
Collapse
Affiliation(s)
- Jay Jin
- Department of Pharmacology, Pennsylvania State College of Medicine, Hershey, Pennsylvania, USA
| | | | | | | | | |
Collapse
|
7
|
Liao BK, Chen RD, Hwang PP. Expression regulation of Na+-K+-ATPase α1-subunit subtypes in zebrafish gill ionocytes. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1897-906. [DOI: 10.1152/ajpregu.00029.2009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In zebrafish ( Danio rerio), six distinct Na+-K+-ATPase (NKA) α1-subunit genes have been identified, and four of them, zatp1a1a.1, zatp1a1a.2, zatp1a1a.4, and zatp1a1a.5, are expressed in embryonic skin where different types of ionocytes appear. The present study attempted to test a hypothesis of whether these NKA α1 paralogues are specifically expressed and function in respective ionocytes. Double fluorescence in situ hybridization analysis demonstrated the specific expression of zatp1a1a.1, zatp1a1a.2, and zatp1a1a. 5 in NKA-rich (NaR) cells, Na+-Cl− cotransporter (NCC)-expressing cells, and H+-ATPase-rich (HR) cells, respectively, based on the colocalization of the three NKA α1 genes with marker genes of the respective ionocytes (epithelial Ca2+ channel in NaR cells; NCC in NCC cells; and H+-ATPase and Na+/H+ exchanger 3b in HR cells). The mRNA expression (by real-time PCR) of zatp1a1a.1, zatp1a1a.2, and zatp1a1a.5 were, respectively, upregulated by low-Ca2+, low-Cl−, and low-Na+ freshwater, which had previously been reported to stimulate uptake functions of Ca2+, Cl−, and Na+. However, zatp1a1a.4 was not colocalized with any of the three types of ionocytes, nor did its mRNA respond to the ambient ions examined. Taken together, zATP1a1a.1, zATP1a1a.2, and zATP1a1a.5 may provide driving force for Na+-coupled cotransporter activity specifically in NaR, NCC, and HR cells, respectively.
Collapse
|
8
|
Wang L, Sewell WF, Kim SD, Shin JT, MacRae CA, Zon LI, Seidman JG, Seidman CE. Eya4 regulation of Na+/K+-ATPase is required for sensory system development in zebrafish. Development 2008; 135:3425-34. [PMID: 18799547 DOI: 10.1242/dev.012237] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To investigate the mechanisms by which mutations in the human transcriptional co-activator EYA4 gene cause sensorineural hearing loss that can occur in association with dilated cardiomyopathy, we studied eya4 expression during zebrafish development and characterized eya4 deficiency. eya4 morphant fish embryos had reduced numbers of hair cells in the otic vesicle and lateral line neuromasts with impaired sensory responses. Analyses of candidate genes that are known to be expressed in a temporal and spatial pattern comparable to eya4 focused our analyses on atp1b2b, which encodes the beta2b subunit of the zebrafish Na+/K+-ATPase. We demonstrate atp1b2b levels are reduced in eya4 morphant fish and that morpholino oligonucleotides targeting the atp1b2b gene recapitulated the eya4 deficiency phenotypes, including heart failure, decreased sensory hair cell numbers in the otic vesicle and neuromasts, and abnormal sensory responses. Furthermore, atp1b2b overexpression rescued these phenotypes in eya4 morphant fish. We conclude that eya4 regulation of Na+/K+-ATPase is crucial for the development of mechanosensory cells and the maintenance of cardiac function in zebrafish.
Collapse
Affiliation(s)
- Libin Wang
- Harvard Medical School, Department of Genetics, and Howard Hughes Medical Institute, Division of Hematology/Oncology, Children's Hospital Boston, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Hwang PP, Lee TH. New insights into fish ion regulation and mitochondrion-rich cells. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:479-97. [PMID: 17689996 DOI: 10.1016/j.cbpa.2007.06.416] [Citation(s) in RCA: 353] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2007] [Revised: 06/18/2007] [Accepted: 06/19/2007] [Indexed: 10/23/2022]
Abstract
Compared to terrestrial animals, fish have to cope with more-challenging osmotic and ionic gradients from aquatic environments with diverse salinities, ion compositions, and pH values. Gills, a unique and highly studied organ in research on fish osmoregulation and ionoregulation, provide an excellent model to study the regulatory mechanisms of ion transport. The present review introduces and discusses some recent advances in relevant issues of teleost gill ion transport and functions of gill ionocytes. Based on accumulating evidence, a conclusive model of NaCl secretion in gills of euryhaline teleosts has been established. Interpretations of results of studies on freshwater fish gill Na+/Cl- uptake mechanisms are still being debated compared with those for NaCl secretion. Current models for Na+/Cl- uptake are proposed based on studies in traditionally used model species. Many reported inconsistencies are claimed to be due to differences among species, various experimental designs, or acclimation conditions. Having the benefit of advanced techniques in molecular/cellular biology, functional genomics, and model animals, several new notions have recently been raised concerning relevant issues of Na+/Cl- uptake pathways. Several new windows have been opened particularly in terms of molecular mechanisms of ionocyte differentiation and energy metabolite transport between gill cells during environmental challenge.
Collapse
Affiliation(s)
- Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, 115, Taiwan.
| | | |
Collapse
|
10
|
Chen H, Leung T, Giger KE, Stauffer AM, Humbert JE, Sinha S, Horstick EJ, Hansen CA, Robishaw JD. Expression of the G protein gammaT1 subunit during zebrafish development. Gene Expr Patterns 2007; 7:574-83. [PMID: 17306630 PMCID: PMC2754307 DOI: 10.1016/j.modgep.2007.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 01/02/2007] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
Here, we report the identification and expression analysis of the zebrafish G protein gammaT1 subunit gene (gngT1) during development. Similar to its human and mouse homologs, we confirm zebrafish gngT1 is expressed in the developing retina, where its transcription overlaps with the photoreceptor cell-specific marker, rhodopsin (rho). Surprisingly, we also show zebrafish gngT1 is expressed in the dorsal diencephalon, where its transcription overlaps with the pineal specific markers, arylalkylamine N-acetyltransferase-2 (annat-2) and extra-ocular rhodopsin (exorh). Analysis of the proximal promoter sequence of the zebrafish gngT1 gene identifies several conserved binding sites for the cone-rod homeobox/orthodenticle (Crx/Otx) homeodomain family of transcription factors. Using a morpholino anti-sense approach in zebrafish, we show that targeted knockdown of otx5 potently suppresses gngT1 expression in the pineal gland, whereas knockdown of crx markedly reduces gngT1 expression in the retina. Taken together, these data indicate that pineal- and retinal-specific expression of the gngT1 gene are controlled by different transcription factors and exogenous signals.
Collapse
Affiliation(s)
- Hui Chen
- Weis Center for Research, Geisinger Health System, Danville, PA 17822, USA
| | - TinChung Leung
- Weis Center for Research, Geisinger Health System, Danville, PA 17822, USA
| | - Kathryn E. Giger
- Weis Center for Research, Geisinger Health System, Danville, PA 17822, USA
| | - Anna M. Stauffer
- Weis Center for Research, Geisinger Health System, Danville, PA 17822, USA
| | - Jasper E. Humbert
- Weis Center for Research, Geisinger Health System, Danville, PA 17822, USA
| | - Soniya Sinha
- Dept. of Biological and Allied Health Sciences, Bloomsburg University, Bloomsburg, PA 17815, USA
| | - Eric J. Horstick
- Dept. of Biological and Allied Health Sciences, Bloomsburg University, Bloomsburg, PA 17815, USA
| | - Carl A. Hansen
- Dept. of Biological and Allied Health Sciences, Bloomsburg University, Bloomsburg, PA 17815, USA
| | - Janet D. Robishaw
- Corresponding author. Tel.: +1 570 271 6659; fax: +1 570 271 6701. E-mail address: (J. D. Robishaw), Mail address: Weis Center for Research, 100 North Academy Ave. Danville,PA 17822, USA
| |
Collapse
|
11
|
Khan KM, Sarfaraz N, Siddiqui S, Nawaz H. Immunohistochemical localization of G protein betagamma subunits in the lateral wall of the rat cochlea. J Anat 2006; 208:205-18. [PMID: 16441565 PMCID: PMC2100195 DOI: 10.1111/j.1469-7580.2006.00526.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The role of G protein-mediated signal transduction in the production of endolymph, an extracellular fluid of unusual ionic composition, is beginning to be understood. The identity of Galpha subunits in the stria vascularis and the spiral ligament of the lateral wall of the cochlear duct is well established. However, little is known about the presence of betagamma subunits. This study used immunohistochemistry to investigate the distribution of G protein betagamma subunits in the lateral wall of the cochlea. Temporal bones of 6- to 8-week-old rats were fixed in 4% paraformaldehyde and 0.1% glutaraldehyde and processed for embedding in paraffin wax. The dewaxed, midmodiolar sections of the cochlea were incubated with subunit-specific polyclonal antibodies. The results show that the pattern of immunoreactivity varies for the G protein beta1-4 and gamma1-3, 5 and 7 subunits in the stria vascularis and spiral ligament. In the stria vascularis, immunoreactivity was detected for beta2, beta3, beta4, gamma1, gamma2 and gamma7 subunits. All five types of fibrocytes in the spiral ligament exhibited positive staining for gamma2 and gamma7. However, immunoreactivity for beta1-4 subunits was variable. Immunoreactivity for gamma3 and gamma5 subunits was not detected in the lateral cochlear wall. The expression pattern of G protein betagamma subunits in lateral wall provides a basis for interpreting the functions of G protein-coupled receptors in cochlear fluid homeostasis.
Collapse
Affiliation(s)
- Khalid M Khan
- Department of Biological & Biomedical Sciences, Faculty of Health Sciences, The Aga Khan University, Karachi, Pakistan.
| | | | | | | |
Collapse
|
12
|
Blasiole B, Canfield VA, Vollrath MA, Huss D, Mohideen MAPK, Dickman JD, Cheng KC, Fekete DM, Levenson R. Separate Na,K-ATPase genes are required for otolith formation and semicircular canal development in zebrafish. Dev Biol 2006; 294:148-60. [PMID: 16566913 DOI: 10.1016/j.ydbio.2006.02.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 02/17/2006] [Accepted: 02/21/2006] [Indexed: 11/21/2022]
Abstract
We have investigated the role of Na,K-ATPase genes in zebrafish ear development. Six Na,K-ATPase genes are differentially expressed in the developing zebrafish inner ear. Antisense morpholino knockdown of Na,K-ATPase alpha1a.1 expression blocked formation of otoliths. This effect was phenocopied by treatment of embryos with ouabain, an inhibitor of Na,K-ATPase activity. The otolith defect produced by morpholinos was rescued by microinjection of zebrafish alpha1a.1 or rat alpha1 mRNA, while the ouabain-induced defect was rescued by expression of ouabain-resistant zebrafish alpha1a.1 or rat alpha1 mRNA. Knockdown of a second zebrafish alpha subunit, alpha1a.2, disrupted development of the semicircular canals. Knockdown of Na,K-ATPase beta2b expression also caused an otolith defect, suggesting that the beta2b subunit partners with the alpha1a.1 subunit to form a Na,K-ATPase required for otolith formation. These results reveal novel roles for Na,K-ATPase genes in vestibular system development and indicate that different isoforms play distinct functional roles in formation of inner ear structures. Our results highlight zebrafish gene knockdown-mRNA rescue as an approach that can be used to dissect the functional properties of zebrafish and mammalian Na,K-ATPase genes.
Collapse
Affiliation(s)
- Brian Blasiole
- Department of Pharmacology, Penn State University College of Medicine, H078, Hershey, PA 17033, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Leung T, Chen H, Stauffer AM, Giger KE, Sinha S, Horstick EJ, Humbert JE, Hansen CA, Robishaw JD. Zebrafish G protein gamma2 is required for VEGF signaling during angiogenesis. Blood 2006; 108:160-6. [PMID: 16537812 PMCID: PMC1895829 DOI: 10.1182/blood-2005-09-3706] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) is a major mediator of pathologic angiogenesis, a process necessary for the formation of new blood vessels to support tumor growth. Historically, VEGF has been thought to signal via receptor tyrosine kinases, which are not typically considered to be G protein dependent. Here, we show that targeted knockdown of the G protein gng2 gene (Ggamma2) blocks the normal angiogenic process in developing zebrafish embryos. Moreover, loss of gng2 function inhibits the ability of VEGF to promote the angiogenic sprouting of blood vessels by attenuating VEGF induced phosphorylation of phospholipase C-gamma1 (PLCgamma1) and serine/threonine kinase (AKT). Collectively, these results demonstrate a novel interaction between Ggamma2- and VEGF-dependent pathways to regulate the angiogenic process in a whole-animal model. Blocking VEGF function using a humanized anti-VEGF antibody has emerged as a promising treatment for colorectal, non-small lung cell, and breast cancers. However, this treatment may cause considerable side effects. Our findings provide a new opportunity for cotargeting G protein- and VEGF-dependent pathways to synergistically block pathologic angiogenesis, which may lead to a safer and more efficacious therapeutic regimen to fight cancer.
Collapse
Affiliation(s)
- Tinchung Leung
- Weis Center for Research, Geisinger Health System, Danville, PA 17822, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Shmukler BE, Kurschat CE, Ackermann GE, Jiang L, Zhou Y, Barut B, Stuart-Tilley AK, Zhao J, Zon LI, Drummond IA, Vandorpe DH, Paw BH, Alper SL. Zebrafish slc4a2/ae2 anion exchanger: cDNA cloning, mapping, functional characterization, and localization. Am J Physiol Renal Physiol 2005; 289:F835-49. [PMID: 15914778 DOI: 10.1152/ajprenal.00122.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Although the zebrafish has been used increasingly for the study of pronephric kidney development, studies of renal ion transporters and channels of the zebrafish remain few. We report the cDNA cloning and characterization of the AE2 anion exchanger ortholog from zebrafish kidney, slc4a2/ae2. The ae2 gene in linkage group 2 encodes a polypeptide of 1,228 aa exhibiting 64% aa identity with mouse AE2a. The exon-intron boundaries of the zebrafish ae2 gene are nearly identical to those of the rodent and human genes. Whole-mount in situ hybridization detects ae2 mRNA in prospective midbrain as early as the five-somite stage, then later in the pronephric primordia and the forming pronephric duct, where it persists through 72 h postfertilization (hpf). Zebrafish Ae2 expressed in Xenopus laevis oocytes mediates Na(+)-independent, electroneutral (36)Cl(-)/Cl(-) exchange moderately sensitive to inhibition by DIDS, is inhibited by acidic intracellular pH and by acidic extracellular pH, but activated by (acidifying) ammonium and by hypertonicity. Zebrafish Ae2 also mediates Cl(-)/HCO(3)(-) exchange in X. laevis oocytes and accumulates in or near the plasma membrane in transfected HEK-293 cells. In 24-48 hpf zebrafish embryos, the predominant but not exclusive localization of Ae2 polypeptide is the apical membrane of pronephric duct epithelial cells. Thus Ae2 resembles its mammalian orthologs in function, mechanism, and acute regulation but differs in its preferentially apical expression in kidney. These results will inform tests of the role of Ae2 in zebrafish kidney development and function.
Collapse
Affiliation(s)
- Boris E Shmukler
- Molecular Medicine and Renal Units, Beth Israel Deaconess Med. Ctr. E/RW763, 330 Brookline Ave., Boston, MA 02215, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Abstract
Historically, it has been assumed that the functional roles of G proteins in receptor recognition and effector regulation are specified by their diverse alpha subunits. However, the discovery of similarly diverse betagamma subunits that participate in both of these functional processes has called this assumption into question; recent work suggests that G proteins function as heterotrimers whose roles in particular receptor signaling pathways are determined by their specific alphabetagamma subunit combinations. Although much remains to be learned, the assembly of specific alphabetagamma subunit combinations seems to involve both structural and spatial factors.
Collapse
Affiliation(s)
- Janet D Robishaw
- 100 N. Academy Ave, Weis Center for Research, Geisinger Clinic, Danville, PA 17822-2614, USA.
| | | |
Collapse
|