Chronic acidosis, glomerular hyperfiltration, and K depletion all lead to increased activities of the proximal tubular Na/H antiporter and Na/3HCO3 cotransporter, effects that persist when the transporters are studied outside the altered environment (memory effect). The intracellular signals mediating these adaptations are presently unknown. We postulate that a number of different extracellular signals occurring acidosis, hyperfiltration, and K deficiency, all converge on a common cellular pathway that effects increased H/HCO3 transporter activities at the transcriptional and translational levels. We have established a model for chronic acidosis in cultured proximal tubule cells, where chronic incubation in acid medium leads to a tissue-specific, protein synthesis-dependent increase in Na/H antiporter activity.
One aim of this grant is to define the cell signalling mechanisms that chronically regulate H/HCO3 transporter activities; and to examine the role of these pathways in mediating the effect of chronic acid incubation on Na/H antiporter activity. Cell signals that will be examined include: 1) phospholipase C/PKC/cell Ca; 2) adenyl cyclase/CAMP/PKA; and 3) cell [Na] and Ph. We will also attempt to establish cell culture models for K depletion and hyperfiltration.
The second aim of this proposal is to study the molecular mechanisms by which the Na/H antiporter cloned by Sardet et al, is chronically regulated by the above determinants. Specifically, we will examine protein abundance, relative distribution of protein between microsomal and plasma membrane fractions, rates of synthesis/degradation, degree of phosphorylation, abundance of MRNA, and rates of MRNA transcription. Lastly, we have a 1400 bp fragment from the promoter/enhancer region of the human Na/H antiporter gene. We will use this to study how the above regulators modify interactions between nuclear proteins and the Na/H antiporter/enhancer region by CAT assay, mobility shift, and Dnase protection assays.
| Zacchia, Miriam; Tian, Xuefei; Zona, Enrica et al. (2018) Acid Stimulation of the Citrate Transporter NaDC-1 Requires Pyk2 and ERK1/2 Signaling Pathways. J Am Soc Nephrol 29:1720-1730 |
| Liu, Liping; Zacchia, Miriam; Tian, Xuefei et al. (2010) Acid regulation of NaDC-1 requires a functional endothelin B receptor. Kidney Int 78:895-904 |
| Zacchia, Miriam; Preisig, Patricia (2010) Low urinary citrate: an overview. J Nephrol 23 Suppl 16:S49-56 |
| Preisig, P A (2007) The acid-activated signaling pathway: starting with Pyk2 and ending with increased NHE3 activity. Kidney Int 72:1324-9 |
| Yang, Xiaojing; Huang, Hai-Chang; Yin, Helen et al. (2007) RhoA required for acid-induced stress fiber formation and trafficking and activation of NHE3. Am J Physiol Renal Physiol 293:F1054-64 |
| Moe, Orson W; Preisig, Patricia A (2006) Dual role of citrate in mammalian urine. Curr Opin Nephrol Hypertens 15:419-24 |
| Laghmani, Kamel; Sakamoto, Aiji; Yanagisawa, Masashi et al. (2005) A consensus sequence in the endothelin-B receptor second intracellular loop is required for NHE3 activation by endothelin-1. Am J Physiol Renal Physiol 288:F732-9 |
| Licht, Christoph; Laghmani, Kamel; Yanagisawa, Masashi et al. (2004) An autocrine role for endothelin-1 in the regulation of proximal tubule NHE3. Kidney Int 65:1320-6 |
| Aruga, Seiji; Pajor, Ana M; Nakamura, Kiyoshi et al. (2004) OKP cells express the Na-dicarboxylate cotransporter NaDC-1. Am J Physiol Cell Physiol 287:C64-72 |
| Alpern, Robert J; Preisig, Patricia A (2004) Dietary acid, endothelins, and sleep. Trans Am Clin Climatol Assoc 115:385-93; discussion 393-4 |
Showing the most recent 10 out of 68 publications
