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| EXPRESSION OF VAMP2-LIKE PROTEIN IN KIDNEY COLLECTING DUCT INTRACELLULAR VESICLES - COLOCALIZATION WITH AQUAPORIN-2 WATER CHANNELS |
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| Author(s): NIELSEN S, MARPLES D, BIRN H, MOHTASHAMI M, DALBY NO, TRIMBLE W, KNEPPER M |
| Source: JOURNAL OF CLINICAL INVESTIGATION Volume: 96 Issue: 4 Pages: 1834-1844 Published: OCT 1995 |
| Times Cited: 117 References: 38 |
| Abstract: Body water balance is controlled by vasopressin, which regulates Aquaporin-2 (AQP2) water channels in kidney collecting duct cells by vesicular trafficking between intracellular vesicles and the plasma membrane, To examine the molecular apparatus involved in vesicle trafficking and vasopressin regulation of AQP2 in collecting duct cells, we tested if targeting proteins expressed in the synaptic vesicles, namely vesicle-associated membrane proteins 1 and 2 (VAMP1 and 2), are expressed in kidney collecting duct, Immunoblotting revealed specific labeling of VAMP2 (18-kD band) but not VAMP1 in membrane fractions prepared from kidney inner medulla, Controls using preadsorbed antibody or preimmune serum were negative, Bands of identical molecular size were detected in immunoblots of brain membrane vesicles and purified synaptic vesicles, VAMP2 in kidney membranes was cleaved by tetanus toxin, revealing a tetanus toxin-sensitive VAMP homologue, Similarly, tetanus toxin cleaved VAMP2 in synaptic vesicles, In kidney inner medulla, VAMP2 was predominantly expressed in the membrane fraction enriched for intracellular vesicles, with little or no VAMP2 in the plasma membrane enriched fraction, This was confirmed by immunocytochemistry using semithin cryosections, which showed mainly vesicular labeling in collecting duct principal cells, with no labeling of intercalated cells, VAMP2 immunolabeling colocalized with AQP2 labeling in intracellular vesicles, as determined by immunoelectron microscopy after double immunolabeling of isolated vesicles. Quantitative analysis of 1,310 vesicles revealed a highly significant association of both AQP2 and VAMP2 in the same vesicles (P < 0.0001), Furthermore, the presence of AQP2 in vesicles immunoisolated with anti-VAMP2 antibodies was confirmed by im munoblotting, In conclusion, VAMP2, a component of the neuronal SNARE; complex, is expressed in vesicles carrying AQP2, suggesting a role in vasopressin-regulated vesicle trafficking of AQP2 water channels. |
| Document Type: Article |
| Language: English |
| Reprint Address: NIELSEN, S (reprint author), AARHUS UNIV, INST ANAT, DEPT CELL BIOL, DK-8000 AARHUS, DENMARK |
Addresses:
1. UNIV TORONTO, DEPT PHYSIOL, TORONTO, ON M5S 1A8 CANADA
2. UNIV TORONTO, NEURODEGENERAT DIS RES CTR, TORONTO, ON M5S 1A8 CANADA
3. AARHUS UNIV, DEPT BIOL MOLEC, DK-8000 AARHUS, DENMARK
4. NHLBI, KIDNEY & ELECTROLYTE METAB LAB, BETHESDA, MD 20892 USA |
| Publisher: ROCKEFELLER UNIV PRESS, 222 E 70TH STREET, NEW YORK, NY 10021 |
| Subject Category: Medicine, Research & Experimental |
| IDS Number: RY954 |
| ISSN: 0021-9738 |
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