Zebrafish enhancer trap line recapitulates embryonic aquaporin 1a expression pattern in vascular endothelial cells

Rehn, Kira; Wong, Kuan Shen; Balciunas, Darius; Sumanas, Saulius

doi:10.1387/ijdb.103249kp

Cited by 16 publications

(14 citation statements)

References 42 publications

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“…Recently, it was demonstrated that AQP1a1 is expressed on the skin of yolk sac in larval zebrafish [16], [17], and expression of zebrafish AQP1a1 in Xenopus oocytes was associated with an increase in water influx [7]. Here we show that in larval zebrafish, AQP1a1 is expressed predominantly on the basolateral membrane of ionocytes on the yolk sac epithelium.…”

Section: Discussionsupporting

confidence: 48%

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The Role of Aquaporin and Tight Junction Proteins in the Regulation of Water Movement in Larval Zebrafish (Danio rerio)

2013

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Teleost fish living in freshwater are challenged by passive water influx; however the molecular mechanisms regulating water influx in fish are not well understood. The potential involvement of aquaporins (AQP) and epithelial tight junction proteins in the regulation of transcellular and paracellular water movement was investigated in larval zebrafish (Danio rerio). We observed that the half-time for saturation of water influx (K u) was 4.3±0.9 min, and reached equilibrium at approximately 30 min. These findings suggest a high turnover rate of water between the fish and the environment. Water influx was reduced by the putative AQP inhibitor phloretin (100 or 500 μM). Immunohistochemistry and confocal microscopy revealed that AQP1a1 protein was expressed in cells on the yolk sac epithelium. A substantial number of these AQP1a1-positive cells were identified as ionocytes, either H+-ATPase-rich cells or Na+/K+-ATPase-rich cells. AQP1a1 appeared to be expressed predominantly on the basolateral membranes of ionocytes, suggesting its potential involvement in regulating ionocyte volume and/or water flux into the circulation. Additionally, translational gene knockdown of AQP1a1 protein reduced water influx by approximately 30%, further indicating a role for AQP1a1 in facilitating transcellular water uptake. On the other hand, incubation with the Ca2+-chelator EDTA or knockdown of the epithelial tight junction protein claudin-b significantly increased water influx. These findings indicate that the epithelial tight junctions normally act to restrict paracellular water influx. Together, the results of the present study provide direct in vivo evidence that water movement can occur through transcellular routes (via AQP); the paracellular routes may become significant when the paracellular permeability is increased.

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Section: Discussionsupporting

confidence: 48%

“…In larval zebrafish, the results of in situ hybridization demonstrated that AQP1a is expressed on the skin of the yolk sac, presumably to regulate water influx [16], [17]. However, it is still unclear whether AQP1 has any physiological role in facilitating transcellular water movement in teleost fish in vivo .…”

Section: Introductionmentioning

confidence: 99%

The Role of Aquaporin and Tight Junction Proteins in the Regulation of Water Movement in Larval Zebrafish (Danio rerio)

2013

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“…A gene-trap fli1b tpl50Gt mutant line was generated in a Tol2 -mediated insertional mutagenesis screen using GBT-B4 gene trap vector (C. Seiler et al, unpublished data, 2015) similar to the recently published GBT-B1. 42-44 The gene trap transposon (Figure IIE in the online-only Data Supplement) integrated into the first intron and near the start of the coding sequence resulting in a Gal4-VP16 fusion protein lacking the ETS DNA-binding domain (Figure IIF through IIH in the online-only Data Supplement); therefore, the mutation is expected to be null or severe hypomorph. 43 Consistent with this view, the gene-trap disruption resulted in an 18.5-fold (5.4±2.0%) reduction in full-length fli1b message as determined by reverse transcription polymerase chain reaction and whole-mount in situ hybridization (Figure IIM, IIN, and IIP in the online-only Data Supplement).…”

Section: Resultsmentioning

confidence: 99%

Etv2 and Fli1b Function Together as Key Regulators of Vasculogenesis and Angiogenesis

Craig

Grajevskaja

Liao

et al. 2015

ATVB

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Objective The E26 transformation-specific domain transcription factor Etv2/Etsrp/ER71 is a master regulator of vascular endothelial differentiation during vasculogenesis, although its later role in sprouting angiogenesis remains unknown. Here, we investigated in the zebrafish model a role for Etv2 and related E26 transformation-specific factors, Fli1a and Fli1b in developmental angiogenesis. Approach and Results Zebrafish fli1a and fli1b mutants were obtained using transposon-mediated gene trap approach. Individual fli1a and fli1b homozygous mutant embryos display normal vascular patterning, yet the angiogenic recovery observed in older etv2 mutant embryos does not occur in embryos lacking both etv2 and fli1b. Etv2 and fli1b double-deficient embryos fail to form any angiogenic sprouts and show greatly increased apoptosis throughout the axial vasculature. In contrast, fli1a mutation did not affect the recovery of etv2 mutant phenotype. Overexpression analyses indicate that both etv2 and fli1b, but not fli1a, induce the expression of multiple vascular markers and of each other. Temporal inhibition of Etv2 function using photoactivatable morpholinos indicates that the function of Etv2 and Fli1b during angiogenesis is independent from the early requirement of Etv2 during vasculogenesis. RNA-Seq analysis and chromatin immunoprecipitation suggest that Etv2 and Fli1b share the same transcriptional targets and bind to the same E26 transformation-specific sites. Conclusions Our data argue that there are 2 phases of early vascular development with distinct requirements of E26 transformation-specific transcription factors. Etv2 alone is required for early vasculogenesis, whereas Etv2 and Fli1b function redundantly during late vasculogenesis and early embryonic angiogenesis.

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“…The abundance of gas-permeable membrane channels is the second key regulator of membrane permeability to CO 2 (Itel et al, 2012). In larval zebrafish, AQP1a1 is expressed in several membranes of potential relevance to CO 2 excretion, including endothelial cells of the arterial vasculature (Rehn et al, 2011), RBCs ( present study; Chen et al, 2010) and ionocytes of the yolk sac epithelium (Chen et al, 2010;Kwong et al, 2013). Loss of RBCs, and hence RBC AQP1a1, by treating the developing zebrafish with phenylhydrazine had no significant impact on CO 2 excretion, and AQP1a1 Values were normalized relative to 18S (for mRNA) or β-actin (for protein), and values for HEA-exposed larvae then were expressed relative to those of the corresponding control group.…”

Section: Discussionmentioning

confidence: 99%

The water channel aquaporin-1a1 facilitates movement of CO2 and ammonia in zebrafish (Danio rerio) larvae

Talbot

Kwong

Gilmour

et al. 2015

Journal of Experimental Biology

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The present study tested the hypothesis that zebrafish (Danio rerio) aquaporin-1a1 (AQP1a1) serves as a multi-functional channel for the transfer of the small gaseous molecules, CO 2 and ammonia, as well as water, across biological membranes. Zebrafish embryos were microinjected with a translation-blocking morpholino oligonucleotide targeted to AQP1a1. Knockdown of AQP1a1 significantly reduced rates of CO 2 and ammonia excretion, as well as water fluxes, in larvae at 4 days post fertilization (dpf ). Because AQP1a1 is expressed both in ionocytes present on the body surface and in red blood cells, the haemolytic agent phenylhydrazine was used to distinguish between the contributions of AQP1a1 to gas transfer in these two locations. Phenylhydrazine treatment had no effect on AQP1a1-linked excretion of CO 2 or ammonia, providing evidence that AQP1a1 localized to the yolk sac epithelium, rather than red blood cell AQP1a1, is the major site of CO 2 and ammonia movements. The possibility that AQP1a1 and the rhesus glycoprotein Rhcg1, which also serves as a dual CO 2 and ammonia channel, act in concert to facilitate CO 2 and ammonia excretion was explored. Although knockdown of each protein did not affect the abundance of mRNA and protein of the other protein under control conditions, impairment of ammonia excretion by chronic exposure to high external ammonia triggered a significant increase in the abundance of AQP1a1 mRNA and protein in 4 dpf larvae experiencing Rhcg1 knockdown. Collectively, these results suggest that AQP1a1 in zebrafish larvae facilitates the movement of CO 2 and ammonia, as well as water, in a physiologically relevant fashion.

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Zebrafish enhancer trap line recapitulates embryonic aquaporin 1a expression pattern in vascular endothelial cells

Cited by 16 publications

References 42 publications

The Role of Aquaporin and Tight Junction Proteins in the Regulation of Water Movement in Larval Zebrafish (Danio rerio)

The Role of Aquaporin and Tight Junction Proteins in the Regulation of Water Movement in Larval Zebrafish (Danio rerio)

Etv2 and Fli1b Function Together as Key Regulators of Vasculogenesis and Angiogenesis

The water channel aquaporin-1a1 facilitates movement of CO2 and ammonia in zebrafish (Danio rerio) larvae

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