Subcellular localization and secretion of activity-dependent neuroprotective protein in astrocytes

Illana Gozes, Sharon Furman, Ruth A. Steingart, Shmuel Mandel, Janet M. Hauser, Douglas E. Brenneman

Research output: Contribution to journalArticlepeer-review

Abstract

Activity-dependent neuroprotective protein (ADNP, ~123562.8 Da), is synthesized in astrocytes and expression of ADNP mRNA is regulated by the neuroprotective peptide vasoactive intestinal peptide (VIP). The gene that encodes ADNP is conserved in human, rat and mouse, and contains a homeobox domain profile that includes a nuclear-export signal and a nuclear-localization signal. ADNP is essential for embryonic brain development, and NAP, an eight-amino acid peptide that is derived from ADNP, confers potent neuroprotection. Here, we investigate the subcellular localization of ADNP through cell fraction-ation gel electrophoresis, immunoblotting and immunocytochemistry usingα-CNAP, an antibody directed to the neuroprotec-tive NAP fragment that constitutes part of an N-terminal epitope of ADNP. Recombinant ADNP was used as a competitive ligand to measure antibody specificity. ADNP-like immunoreactivity was found in the nuclear cell fraction of astrocytes and in the cytoplasm. In the cytoplasm, ADNP-like immunoreactivity colocalized with tubulin-like immunoreactivity and with microtubular structures, but not with actin microfilaments. Because microtubules are key components of developing neurons and brain, possible interaction between tubulin and ADNP might indicate a functional correlate to the role ofADNP in the brain. In addition, ADNP-like immunoreactivity in the extracellular milieu of astrocytes increased by ~1.4 fold after incubation of the astrocytes with VIP. VIP is known to cause astrocytes to secrete neuroprotective/neurotrophic factors, and we suggest that ADNP constitutes part of this VIP-stimulated protective milieu.

Original languageEnglish
Pages (from-to)193-199
Number of pages7
JournalNeuron Glia Biology
Volume1
Issue number3
DOIs
StatePublished - 2004

Keywords

  • ADNP
  • homeobox brain development
  • microtubules
  • secreted proteins

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