Alternative Splicing Controls Neuronal Expression of v-ATPase Subunit a1 and Sorting to Nerve Terminals

Philippe Fossier,Sandrine Poëa-Guyon,Nicolas Morel,Muriel Amar

doi:10.1074/jbc.m600927200

Abstract

Vacuolar proton ATPase accumulates protons inside various intracellular organelles such as synaptic vesicles; its membrane domain V0 could also be involved in membrane fusion. These different functions could require vacuolar proton ATPases possessing different V0 subunit a isoforms. In vertebrates, four genes encode isoforms a1-a4, and a1 variants are also generated by alternative splicing. We identified a novel a1 splice variant a1-IV and showed that the two a1 variants containing exon C are specifically expressed in neurons. Single neurons coexpress a2, a1-I, and a1-IV, and these subunit a isoforms are targeted to different membrane compartments. Recombinant a2 was accumulated in the trans-Golgi network, and a1-I was concentrated in axonal varicosities, whereas a1-IV was sorted to both distal dendrites and axons. Our results indicate that alternative splicing of exon N controls differential sorting of a1 variants to nerve terminals or distal dendrites, whereas exon C regulates their neuronal expression.

Highlights

In neurons, the V1 and V0 domains are transported independently in the axon and assemble once arrived in nerve terminals [12]. v-ATPase is present both in the presynaptic plasma membrane [13] and in the membrane of synaptic vesicles [14, 15]
We looked for the forth possible splice variant of a1, a1-IV, containing both exon N and exon C
We have detected in rat brain a fourth a1 splice variant, a1-IV, that contains both the N and C exons

Summary

Introduction

The V1 and V0 domains are transported independently in the axon and assemble once arrived in nerve terminals [12]. v-ATPase is present both in the presynaptic plasma membrane [13] and in the membrane of synaptic vesicles [14, 15]. We studied the expression of different v-ATPase subunit a isoforms in rat neurons.

Results

Conclusion