Regulated sodium transport in the renal connecting tubule (CNT) via the epithelial sodium channel (ENaC). 2009

Johannes Loffing, and Christoph Korbmacher
Institute of Anatomy, University of Zurich, Switzerland. johannes.loffing@anatom.uzh.ch

The aldosterone-sensitive distal nephron (ASDN) includes the late distal convoluted tubule 2, the connecting tubule (CNT) and the collecting duct. The appropriate regulation of sodium (Na(+)) absorption in the ASDN is essential to precisely match urinary Na(+) excretion to dietary Na(+) intake whilst taking extra-renal Na(+) losses into account. There is increasing evidence that Na(+) transport in the CNT is of particular importance for the maintenance of body Na(+) balance and for the long-term control of extra-cellular fluid volume and arterial blood pressure. Na(+) transport in the CNT critically depends on the activity and abundance of the amiloride-sensitive epithelial sodium channel (ENaC) in the luminal membrane of the CNT cells. As a rate-limiting step for transepithelial Na(+) transport, ENaC is the main target of hormones (e.g. aldosterone, angiotensin II, vasopressin and insulin/insulin-like growth factor 1) to adjust transepithelial Na(+) transport in this tubular segment. In this review, we highlight the structural and functional properties of the CNT that contribute to the high Na(+) transport capacity of this segment. Moreover, we discuss some aspects of the complex pathways and molecular mechanisms involved in ENaC regulation by hormones, kinases, proteases and associated proteins that control its function. Whilst cultured cells and heterologous expression systems have greatly advanced our knowledge about some of these regulatory mechanisms, future studies will have to determine the relative importance of the various pathways in the native tubule and in particular in the CNT.

UI MeSH Term Description Entries
D007328 Insulin A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1). Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D007334 Insulin-Like Growth Factor I A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor. IGF-I,Somatomedin C,IGF-1,IGF-I-SmC,Insulin Like Growth Factor I,Insulin-Like Somatomedin Peptide I,Insulin Like Somatomedin Peptide I
D007685 Kidney Tubules, Collecting Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of Bellini) which opens on the summit of the papilla. Kidney Collecting Ducts,Kidney Collecting Duct,Collecting Duct, Kidney,Collecting Ducts, Kidney
D006706 Homeostasis The processes whereby the internal environment of an organism tends to remain balanced and stable. Autoregulation
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000075702 Nedd4 Ubiquitin Protein Ligases E3 ubiquitin ligases that consist of four WW DOMAINS. They accept UBIQUITIN from E2 UBIQUITIN-CONJUGATING ENZYME as a thioester via their C-terminal HECT domains and transfer it specifically to the 63rd LYSINE residue (Lys-63) of target proteins. NEDD4 targets include many proteins and receptors with important functions for cell growth and homeostasis such as VEGFR-2; FGFR1 TYROSINE KINASE; and ERBB-4 RECEPTOR. They play a critical role in the internalization of these receptors, their degradation by LYSOSOMES, and also function as part of the ESCRT complex in VIRUS RELEASE. Nedd4 Proteins,Neuronal Precursor Cell-Expressed Developmentally Down-Regulated 4 Ligase,Neuronal Precursor Cell Expressed Developmentally Down Regulated 4 Ligase
D000076204 WNK Lysine-Deficient Protein Kinase 1 A serine-threonine kinase which plays an important role in the regulation of electrolyte homeostasis, cell signaling, survival, and proliferation. It functions as an activator and inhibitor of sodium-coupled chloride co-transporters and as an inhibitor of potassium-coupled chloride co-transporters. Mutations in the WNK1 gene are associated with type 2C PSEUDOHYPOALDOSTERONISM and type 2A HEREDITARY SENSORY AND AUTONOMIC NEUROPATHIES. WNK Lysine Deficient Protein Kinase 1
D000450 Aldosterone A hormone secreted by the ADRENAL CORTEX that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Aldosterone, (+-)-Isomer,Aldosterone, (11 beta,17 alpha)-Isomer
D000804 Angiotensin II An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the C-terminal by ANGIOTENSIN CONVERTING ENZYME. The amino acid in position 5 varies in different species. To block VASOCONSTRICTION and HYPERTENSION effect of angiotensin II, patients are often treated with ACE INHIBITORS or with ANGIOTENSIN II TYPE 1 RECEPTOR BLOCKERS. Angiotensin II, Ile(5)-,Angiotensin II, Val(5)-,5-L-Isoleucine Angiotensin II,ANG-(1-8)Octapeptide,Angiotensin II, Isoleucine(5)-,Angiotensin II, Valine(5)-,Angiotensin-(1-8) Octapeptide,Isoleucine(5)-Angiotensin,Isoleucyl(5)-Angiotensin II,Valyl(5)-Angiotensin II,5 L Isoleucine Angiotensin II,Angiotensin II, 5-L-Isoleucine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

Related Publications

Johannes Loffing, and Christoph Korbmacher
October 1982, The American journal of physiology,
Johannes Loffing, and Christoph Korbmacher
June 2003, Pflugers Archiv : European journal of physiology,
Johannes Loffing, and Christoph Korbmacher
November 2010, American journal of physiology. Regulatory, integrative and comparative physiology,
Johannes Loffing, and Christoph Korbmacher
August 2021, The Journal of general physiology,
Johannes Loffing, and Christoph Korbmacher
March 2003, The Journal of physiology,
Johannes Loffing, and Christoph Korbmacher
March 2016, Metabolism: clinical and experimental,
Johannes Loffing, and Christoph Korbmacher
February 2019, EBioMedicine,
Johannes Loffing, and Christoph Korbmacher
February 2019, Molecular brain,
Johannes Loffing, and Christoph Korbmacher
January 2011, Journal of biomedicine & biotechnology,
Johannes Loffing, and Christoph Korbmacher
January 2000, Nihon rinsho. Japanese journal of clinical medicine,
Copied contents to your clipboard!