TY  - JOUR
AU  - Milatz, Susanne
AU  - Himmerkus, Nina
AU  - Wulfmeyer, Vera Christine
AU  - Drewell, Hoora
AU  - Mutig, Kerim
AU  - Hou, Jianghui
AU  - Breiderhoff, Tilman
AU  - Müller, Dominik
AU  - Fromm, Michael
AU  - Bleich, Markus
AU  - Günzel, Dorothee
TI  - Mosaic expression of claudins in thick ascending limbs of Henle results in spatial separation of paracellular Na+ and Mg2+ transport.
JO  - Proceedings of the National Academy of Sciences of the United States of America
VL  - 114
IS  - 2
SN  - 0027-8424
CY  - Washington, DC
PB  - National Acad. of Sciences
M1  - DZNE-2025-00367
SP  - E219 - E227
PY  - 2017
AB  - The thick ascending limb (TAL) of Henle's loop drives paracellular Na+, Ca2+, and Mg2+ reabsorption via the tight junction (TJ). The TJ is composed of claudins that consist of four transmembrane segments, two extracellular segments (ECS1 and -2), and one intracellular loop. Claudins interact within the same (cis) and opposing (trans) plasma membranes. The claudins Cldn10b, -16, and -19 facilitate cation reabsorption in the TAL, and their absence leads to a severe disturbance of renal ion homeostasis. We combined electrophysiological measurements on microperfused mouse TAL segments with subsequent analysis of claudin expression by immunostaining and confocal microscopy. Claudin interaction properties were examined using heterologous expression in the TJ-free cell line HEK 293, live-cell imaging, and Förster/FRET. To reveal determinants of interaction properties, a set of TAL claudin protein chimeras was created and analyzed. Our main findings are that (i) TAL TJs show a mosaic expression pattern of either cldn10b or cldn3/cldn16/cldn19 in a complex; (ii) TJs dominated by cldn10b prefer Na+ over Mg2+, whereas TJs dominated by cldn16 favor Mg2+ over Na+; (iii) cldn10b does not interact with other TAL claudins, whereas cldn3 and cldn16 can interact with cldn19 to form joint strands; and (iv) further claudin segments in addition to ECS2 are crucial for trans interaction. We suggest the existence of at least two spatially distinct types of paracellular channels in TAL: a cldn10b-based channel for monovalent cations such as Na+ and a spatially distinct site for reabsorption of divalent cations such as Ca2+ and Mg2.
KW  - Animals
KW  - Claudins: genetics
KW  - Claudins: metabolism
KW  - HEK293 Cells
KW  - Humans
KW  - Loop of Henle: metabolism
KW  - Loop of Henle: physiology
KW  - Magnesium: metabolism
KW  - Mice, Inbred C57BL
KW  - Mice, Knockout
KW  - Rats, Sprague-Dawley
KW  - Sodium: metabolism
KW  - Tight Junctions: metabolism
KW  - FRET (Other)
KW  - claudin interaction (Other)
KW  - microperfusion (Other)
KW  - paracellular ion transport (Other)
KW  - tight junction (Other)
KW  - Claudins (NLM Chemicals)
KW  - Sodium (NLM Chemicals)
KW  - Magnesium (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:28028216
C2  - pmc:PMC5240732
DO  - DOI:10.1073/pnas.1611684114
UR  - https://pub.dzne.de/record/276854
ER  -