Abstract:The vulnerability of neurons and the irreversibility of loss make discoveries of neuroprotective compounds fundamentally important. Here, the complete coding sequence of a novel protein (828 amino acids, pI 5.99), derived from mouse neuroglial cells, is revealed. The sequence contained (1) a neuroprotective peptide, NAPVSIPQ, sharing structural and immunological homologies with the previously reported, activity-dependent neurotrophic factor; (2) a glutaredoxin active site; and (3) a zinc binding domain. Gene expression was enriched in the mouse hippocampus and cerebellum and augmented in the presence of the neuropeptide vasoactive intestinal peptide, in cerebral cortical astrocytes. In mixed neuronastrocyte cultures, NAPVSIPQ provided neuroprotection at subfemtomolar concentrations against toxicity associated with tetrodotoxin (electrical blockade), the ␤-amyloid peptide (the Alzheimer's disease neurotoxin), N-methyl-D-aspartate (excitotoxicity), and the human immunodeficiency virus envelope protein. Daily NAPVSIPQ injections to newborn apolipoprotein E-deficient mice accelerated the acquisition of developmental reflexes and prevented short-term memory deficits. Comparative studies suggested that NAPVSIPQ was more efficacious than other neuroprotective peptides in the apolipoprotein E-deficiency model. A potential basis for rational drug design against neurodegeneration is suggested with NAPVSIPQ as a lead compound. The relative enrichment of the novel mRNA transcripts in the brain and the increases found in the presence of vasoactive intestinal peptide, an established neuroprotective substance, imply a role for the cloned protein in neuronal function. Key Words: Vasoactive intestinal peptide-Apolipoprotein E-Learning and memory-Neuronal survival-Molecular cloning-mRNA.

The clinical manifestations of AIDS (acquired immune deficiency syndrome) often include neuropsychiatric and neurological deficits, including early memory loss and progressive dementia. HIV (human immunodeficiency virus), the aetiological agent of AIDS, is probably carried by infected macrophages in the central nervous system. The virus enters cells by binding its envelope glycoprotein gp120 to the CD4 antigen present on brain and immune cells. From the data reported in this paper, we now suggest that the neuronal deficits associated with HIV may not be entirely a result of infectivity, but that gp120 shed from HIV could directly produce the neuropathology as a result of its interference with endogenous neurotrophic substances. It is known that an analogue of a sequence contained in vasoactive intestinal peptide (VIP) occurs in all known sequenced gp120 isolates and that VIP is important for neuronal survival in cell culture. Here we show that purified gp120 from two diverse HIV isolates and a recombinant gp120 from a third isolate were all potent in specifically producing significant neuronal cell death in dissociated hippocampal cultures derived from fetal mice, and that this could be reduced by monoclonal antibodies against the murine CD4 antigen and completely antagonized by VIP.

We have recently cloned the mouse activity-dependent neuroprotective protein (ADNP). Here, we disclose the cloning of human ADNP (hADNP) from a fetal brain cDNA library. Comparative sequence analysis of these two ADNP orthologs indicated 90% identity at the mRNA level. Several single nucleotide polymorphic sites were noticed. The deduced protein structure contained nine zinc fingers, a proline-rich region, a nuclear bipartite localization signal, and a homeobox domain profile, suggesting a transcription factor function. Further comparative analysis identified an ADNP paralog (33% identity and 46% similarity), indicating that these genes belong to a novel protein family with a nine-zinc finger motif followed by a homeobox domain. The hADNP gene structure spans ϳ40 kilobases and includes five exons and four introns with alternative splicing of an untranslated second exon. The hADNP gene was mapped to chromosome 20q12-13.2, a region associated with aggressive tumor growth, frequently amplified in many neoplasias, including breast, bladder, ovarian, pancreatic, and colon cancers. hADNP mRNA is abundantly expressed in distinct normal tissues, and high expression levels were encountered in malignant cells. Down-regulation of ADNP by antisense oligodeoxynucleotides up-regulated the tumor suppressor p53 and reduced the viability of intestinal cancer cells by 90%. Thus, ADNP is implicated in maintaining cell survival, perhaps through modulation of p53.Mouse activity-dependent neuroprotective protein (mADNP), 1 a novel vasoactive intestinal peptide (VIP)-responsive gene, was recently cloned (1). The relative enrichment of mADNP transcripts in the cerebellum, cortex, hippocampus, medulla, and midbrain and the increases found in the presence of VIP, an established neuroprotective substance (2), implied a potential function in brain metabolism. Specifically, mADNP mRNA increased 2-3-fold in astroglial cells incubated for 3 h in the presence of nanomolar amounts of VIP (1). Another tissue containing increased mADNP transcripts is the mouse testis, a highly proliferative tissue, suggesting the involvement of ADNP in cell division.As deregulation of oncogenes has been associated with neurodegeneration (3), pathways that regulate neuronal survival may impinge upon cancer proliferation. VIP regulates both neuronal survival and cell division (2). A system whereby labeled VIP is suggested as a tumor marker has been proposed, localizing in vivo tumors of patients with gastrointestinal neuroendocrine cancers as well as pancreatic and colonic adenocarcinomas (4). Other studies have identified a very high incidence of VIP receptor binding in breast, ovarian, endometrial, prostate, bladder, lung, esophageal, colonic, and pancreatic tumors as well as in neuroendocrine and brain tumors (5). However, the VIP effect on cancer growth depends on the specific tumor and may be stimulatory (6, 7) or inhibitory (8). In view of the high incidence of tumors containing VIP receptors, a potential intervention in tumor growth may employ a gene downstr...

Abstract