AKAP79/150 recruits the transcription factor NFAT to regulate signaling to the nucleus by neuronal L-type Ca2+ channels

Mol Biol Cell. 2019 Jul 1;30(14):1743-1756. doi: 10.1091/mbc.E19-01-0060. Epub 2019 May 15.

Abstract

In neurons, regulation of activity-dependent transcription by the nuclear factor of activated T-cells (NFAT) depends upon Ca2+ influx through voltage-gated L-type calcium channels (LTCC) and NFAT translocation to the nucleus following its dephosphorylation by the Ca2+-dependent phosphatase calcineurin (CaN). CaN is recruited to the channel by A-kinase anchoring protein (AKAP) 79/150, which binds to the LTCC C-terminus via a modified leucine-zipper (LZ) interaction. Here we sought to gain new insights into how LTCCs and signaling to NFAT are regulated by this LZ interaction. RNA interference-mediated knockdown of endogenous AKAP150 and replacement with human AKAP79 lacking its C-terminal LZ domain resulted in loss of depolarization-stimulated NFAT signaling in rat hippocampal neurons. However, the LZ mutation had little impact on the AKAP-LTCC interaction or LTCC function, as measured by Förster resonance energy transfer, Ca2+ imaging, and electrophysiological recordings. AKAP79 and NFAT coimmunoprecipitated when coexpressed in heterologous cells, and the LZ mutation disrupted this association. Critically, measurements of NFAT mobility in neurons employing fluorescence recovery after photobleaching and fluorescence correlation spectroscopy provided further evidence for an AKAP79 LZ interaction with NFAT. These findings suggest that the AKAP79/150 LZ motif functions to recruit NFAT to the LTCC signaling complex to promote its activation by AKAP-anchored calcineurin.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • A Kinase Anchor Proteins / chemistry
  • A Kinase Anchor Proteins / metabolism*
  • Amino Acid Motifs
  • Animals
  • Calcineurin / metabolism
  • Calcium Channels, L-Type / metabolism*
  • Calcium Signaling
  • Cell Line
  • Cell Nucleus / metabolism*
  • Cells, Cultured
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Dendritic Spines / metabolism
  • Hippocampus / cytology
  • Models, Biological
  • NFATC Transcription Factors / metabolism*
  • Neurons / metabolism*
  • Protein Binding
  • Protein Transport
  • Rats, Sprague-Dawley
  • Signal Transduction*
  • Transcription, Genetic

Substances

  • A Kinase Anchor Proteins
  • AKAP5 protein, human
  • Calcium Channels, L-Type
  • NFATC Transcription Factors
  • Cyclic AMP-Dependent Protein Kinases
  • Calcineurin