Phosphate (Pi)-regulated heterodimerization of the high-affinity sodium-dependent Pi transporters PiT1/Slc20a1 and PiT2/Slc20a2 underlies extracellular Pi sensing independently of Pi uptake

Bon, Nina; Couasnay, Greig; Bourgine, Annabelle; Sourice, Sophie; Beck-Cormier, Sarah; Guicheux, Jérôme; Beck, Laurent

doi:10.1074/jbc.m117.807339

Cited by 91 publications

(100 citation statements)

References 71 publications

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“…25 Using isolated bone shafts, the authors showed that Pit-2 is required for proper secretion of FGF-23 in response to high Pi media and the same group recently proposed that both Pit-1 and Pit-2 mediate Pi-sensing independently of their transport activity. 27 Since, in our model, the expression of Pit-2 and Pit-1 in bones is normal, the response of FGF-23 to dietary Pi is preserved. Unlike the above parameters, the hypercalciuric response to low dietary Pi was exacerbated in our f/f mice, an effect associated with higher 1,25(OH) 2 D 3 levels.…”

Section: Discussionmentioning

confidence: 93%

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D₃ upon dietary restriction of phosphate

et al. 2020

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Aim Several Na+‐dependent phosphate cotransporters, namely NaPi‐IIb/SLC34A2, Pit‐1/SLC20A1 and Pit‐2/SLC20A2, are expressed at the apical membrane of enterocytes but their contribution to active absorption of phosphate is unclear. The aim of this study was to compare their pattern of mRNA expression along the small and large intestine and to analyse the effect of intestinal depletion of Pit‐2 on phosphate homeostasis. Methods Intestinal epithelial Pit‐2‐deficient mice were generated by crossing floxed Pit‐2 with villin‐Cre mice. Mice were fed 2 weeks standard or low phosphate diets. Stool, urine, plasma and intestinal and renal tissue were collected. Concentration of electrolytes and hormones, expression of mRNAs and proteins and intestinal transport of tracers were analysed. Results Intestinal mRNA expression of NaPi‐IIb and Pit‐1 is segment‐specific, whereas the abundance of Pit‐2 mRNA is more homogeneous. In ileum, NaPi‐IIb mRNA expression is restricted to enterocytes, whereas Pit‐2 mRNA is found in epithelial and non‐epithelial cells. Overall, their mRNA expression is not regulated by dietary phosphate. The absence of Pit‐2 from intestinal epithelial cells does not affect systemic phosphate homeostasis under normal dietary conditions. However, in response to dietary phosphate restriction, Pit‐2‐deficient mice showed exacerbated hypercalciuria and sustained elevation of 1,25(OH)2 vitamin D3. Conclusions In mice, the intestinal Na+/phosphate cotransporters are not coexpressed in all segments. NaPi‐IIb but not Pit‐2 mRNA is restricted to epithelial cells. Intestinal epithelial Pit‐2 does not contribute significantly to absorption of phosphate under normal dietary conditions. However, it may play a more significant role upon dietary phosphate restriction.

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Section: Discussionmentioning

confidence: 93%

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D₃ upon dietary restriction of phosphate

et al. 2020

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“…The non-effect by PiT1 siRNA could be explained by the long half-life of the protein, an issue that can be addressed only when a good antibody is obtained. Also, PiT1 has additional functions, such as proliferation/apoptosis (Beck et al, 2009;Kongsfelt, Byskov, Pedersen, & Pedersen, 2014) and P i sensing (Bon et al, 2018;Salaün et al, 2002), and at least in vascular smooth muscle cells, the protein is also expressed intracellularly (Villa-Bellosta, Levi, & Sorribas, 2009a).…”

Section: Discussionmentioning

confidence: 99%

Identification and expression analysis of type II and type III P_i transporters in the opossum kidney cell line

Guillén

Caldas

Levi

et al. 2018

Experimental Physiology

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New Findings What is the central question of this study?The opossum kidney (OK) cell line is the main in vitro model of proximal tubular Pi transport, but it is incomplete because only the NaPiIIa Pi transporter has been identified. What is the main finding and its importance?We have cloned and characterized the Pi transporters NaPiIIc, PiT1 and PiT2 from OK cells and have analysed the relevance of the four transporters to Pi transport. All four transporters are involved in the upregulated Pi transport of cells incubated using a low‐Pi medium, and only PiT1 is not involved in basal transport. Abstract The apical membrane of renal proximal tubular epithelial cells is the main controller of phosphate homeostasis, because it determines the rate of urinary Pi excretion. The opossum kidney (OK) cell line is a good model for studying this function, but only NaPiIIa (NaPi4) has been identified to date as a Pi transporter in this cell line. In this work, we have identified three additional Pi transporters that are present in OK cells: NaPiIIc, PiT1 and PiT2. All three sequences are similar to the corresponding orthologues, but PiT1 is missing the first transmembrane domain. Confluent cells exhibit characteristics of type II Pi transport, which increases with alkalinity and is inhibited by phosphonoformic acid (PFA), and they mainly express NaPiIIa and NaPiIIc, with a low abundance of PiT1 and PiT2. Proliferating cells show a higher expression of PiT1 and PiT2 and a low expression of NaPiIIa and NaPiIIc. Adaptation to a low Pi concentration for 24 h induces the expression of RNA from NaPiIIa and NaPiIIc, which is not prevented by actinomycin D. Small interfering RNA transfections revealed that PiT1 is not necessary for Pi transport, but it is necessary for adaptation to a low Pi, similar to NaPiIIa and PiT2. Our study reveals the complexity of the coordination between the four Pi transporters, the variability of RNA expression according to confluence and the heterogeneous correlation between Pi transport and RNA levels.

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“…BRET assay is very efficient to evaluate the direct interaction of different proteins [26][27][28]. To further evaluate the existence of 5-HT1AR-OX2R heterodimer, we used BRET analysis to determine whether 5-HT1AR interacted with OX2R directly.…”

Section: The Direct Interaction Between 5-ht1ar and Ox2r In Hek293t Cmentioning

confidence: 99%

Signaling transduction regulated by 5-hydroxytryptamine 1A receptor and orexin receptor 2 heterodimers

Wang

Cheng

et al. 2019

Cellular Signalling

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As G-protein-coupled receptors (GPCRs), 5-hydroxytryptamine 1A receptor (5-HT1AR) and orexin receptor 2 (OX2R) regulate the levels of the cellular downstream molecules. The heterodimers of different GPCRs play important roles in various of neurological diseases. Moreover, 5-HT1AR and OX2R are involved in the pathogenesis of neurological diseases such as depression with deficiency of hippocampus plasticity. However, the direct interaction of the two receptors remains elusive. In the present study, we firstly demonstrated the heterodimer formation of 5-HT1AR and OX2R. Exchange protein directly activated by cAMP (Epac) cAMP bioluminescence resonance energy transfer (BRET) biosensor analysis revealed that the expression levels of cellular cAMP significantly increased in HEK293T cells transfected with the two receptors compared with the 5-HT1AR group. Additionally, the cellular level of calcium was upregulated robustly in HEK293T cells co-transfected with 5-HT1AR and OX2R group after agonist treatment. Furthermore, western blotting data showed that 5-HT1AR and OX2R heterodimer decreased the levels of phosphorylation of extracellular signal-regulated kinase (ERK) and cAMP-response element-binding protein (CREB). These results not only unraveled the formation of 5-HT1AR and OX2R heterodimer but also suggested that the heterodimer affected the downstream signaling pathway, which will provide new insights into the function of the two receptors in the brain.

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Phosphate (Pi)-regulated heterodimerization of the high-affinity sodium-dependent Pi transporters PiT1/Slc20a1 and PiT2/Slc20a2 underlies extracellular Pi sensing independently of Pi uptake

Cited by 91 publications

References 71 publications

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D₃ upon dietary restriction of phosphate

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D₃ upon dietary restriction of phosphate

Identification and expression analysis of type II and type III P_i transporters in the opossum kidney cell line

Signaling transduction regulated by 5-hydroxytryptamine 1A receptor and orexin receptor 2 heterodimers

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Phosphate (Pi)-regulated heterodimerization of the high-affinity sodium-dependent Pi transporters PiT1/Slc20a1 and PiT2/Slc20a2 underlies extracellular Pi sensing independently of Pi uptake

Cited by 91 publications

References 71 publications

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D3 upon dietary restriction of phosphate

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D3 upon dietary restriction of phosphate

Identification and expression analysis of type II and type III Pi transporters in the opossum kidney cell line

Signaling transduction regulated by 5-hydroxytryptamine 1A receptor and orexin receptor 2 heterodimers

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Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D₃ upon dietary restriction of phosphate

Intestinal epithelial ablation of Pit‐2/Slc20a2 in mice leads to sustained elevation of vitamin D₃ upon dietary restriction of phosphate

Identification and expression analysis of type II and type III P_i transporters in the opossum kidney cell line