Publication Date:
2016-03-31
Description:
Transcellular Ca 2+ transport in the late distal convoluted tubule and connecting tubule (DCT2/CNT) of the kidney is a finely controlled process mediated by the transient receptor potential vanilloid type 5 (TRPV5) channel. A complex-type- N -glycan bound at the extracellular residue Asn358 of TRPV5 through post-translational glycosylation has been postulated to regulate the activity of TRPV5 channels. Using in vitro Ca 2+ transport assays, immunoblot analysis, immunohistochemistry, patch clamp electrophysiology and total internal reflection fluorescence microscopy, it is demonstrated that the glycosidase β-galactosidase (β-gal), an enzyme that hydrolyzes galactose, stimulates TRPV5 channel activity. However, the activity of the non-glycosylated TRPV N358Q mutant was not altered in the presence of β-gal, showing that the stimulation is dependent on the presence of the TRPV5 N -glycan. In addition, β-gal was found to stimulate transcellular Ca 2+ transport in isolated mouse primary DCT2/CNT cells. β-gal expression was detected in the apical membrane of the proximal tubules, and the protein was found in mouse urine. In summary, β-gal is present in the pro-urine from where it is thought to stimulate TRPV5 activity.
Print ISSN:
0959-6658
Electronic ISSN:
1460-2423
Topics:
Biology
,
Medicine
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