Functional human NAIP promoter transcription regulatory elements for the NAIP and PsiNAIP genes.
ABSTRACT Neuronal apoptosis inhibitory protein (NAIP) has been shown to inhibit apoptosis in vitro and in vivo with an expression which is regulated in a variety of cells and tissues and may be modulated by a variety of external stimuli. To understand the molecular basis of the transcriptional regulation of the NAIP gene, we have analyzed the 5'-flanking region and transcription of the human NAIP gene. The functional promoter and silencer elements were identified by luciferase reporter constructs in transient transfection experiments using four different human cells. Although the location of the functional elements were shared among the different cells used, the activities for the NAIP promoter varied. Further, cell type-specific protein binding activities were observed by an electrophoretic mobility shift assay (EMSA). EMSA analysis with specific antibodies and DNA sequence analysis identified the POU domain transcription factor Brn-2 as a candidate transcriptional regulator of the NAIP gene. The DNA sequence of the promoter region of the PsiNAIP gene, a copy gene for NAIP, was nearly identical to that of the NAIP gene, indicating a common regulatory mechanism for transcription of the NAIP and PsiNAIP genes. Indeed, the transcript of the PsiNAIP gene was identified. These results provided the first evidence for the functional promoter and candidate transcriptional factor for the NAIP gene and transcription of the PsiNAIP gene.
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ABSTRACT: Fimbria-fornix (FF), the septo-hippocampal pathway, was transected to model Alzheimer's disease (AD), which is characterized by loss of cholinergic afferent fibers in hippocampus. Various alternations may happen in the deafferented hippocampus. In this study, we determined the expression of Brn-4 in hippocampus after FF lesion. RT-PCR and Western blot showed that mRNA transcription and protein of Brn-4 increased significantly and reached to the peak at day 14 after FF lesion. Hybridization and immunohistochemistry indicated that Brn-4 signals in hippocampus and dentate gyrus (DG) of the deafferented side were significantly stronger than the normal side. More Brn-4 positive cells were identified in the DG of deafferented hippocampus. In the pyramidal and granular cells, Brn-4 positive cells were all NeuN positive neurons, whereas in the neurogenic area, subgranular zone (SGZ), only a part of Brn-4 positive cells were NeuN positive, and these Brn-4/NeuN double positive neurons in SGZ and hilus of DG increased significantly after the trauma induced by FF lesion. In vitro Brn-4 antibody attenuated the role of extract from deafferented hippocampus in promoting differentiation of hippocampal progenitors into MAP-2 positive neurons. This study demonstrated that after FF lesion, Brn-4 in the deafferented hippocampus was upregulated and might play an important role in inducing local progenitors to differentiate into neurons, which may compensate for the loss of cholinergic afferent fibers or other dysfunctions.Hippocampus 11/2008; 19(2):176-86. · 5.49 Impact Factor
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ABSTRACT: The human neuronal apoptosis inhibitory protein (NAIP) gene is no longer principally considered a member of the Inhibitor of Apoptosis Protein (IAP) family, as its domain structure and functions in innate immunity also warrant inclusion in the Nod-Like Receptor (NLR) superfamily. NAIP is located in a region of copy number variation, with one full length and four partly deleted copies in the reference human genome. We demonstrate that several of the NAIP paralogues are expressed, and that novel transcripts arise from both internal and upstream transcription start sites. Remarkably, two internal start sites initiate within Alu short interspersed element (SINE) retrotransposons, and a third novel transcription start site exists within the final intron of the GUSBP1 gene, upstream of only two NAIP copies. One Alu functions alone as a promoter in transient assays, while the other likely combines with upstream L1 sequences to form a composite promoter. The novel transcripts encode shortened open reading frames and we show that corresponding proteins are translated in a number of cell lines and primary tissues, in some cases above the level of full length NAIP. Interestingly, some NAIP isoforms lack their caspase-sequestering motifs, suggesting that they have novel functions. Moreover, given that human and mouse NAIP have previously been shown to employ endogenous retroviral long terminal repeats as promoters, exaptation of Alu repeats as additional promoters provides a fascinating illustration of regulatory innovations adopted by a single gene.PLoS ONE 02/2009; 4(6):e5761. · 3.73 Impact Factor
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ABSTRACT: A mechanism for survival of prostate cancer cells in an androgen-deprived environment remains elusive. Here, we find that expression of neuronal apoptosis inhibitory protein (NAIP) was significantly increased in vivo and in vitro in response to androgen deprivation therapy (ADT). Increased expression of NAIP corresponded to increased DNA-binding activity of NF-kappaB that physically associated to previously uncharacterized kappaB-like sites in the NAIP locus. Importantly, expression of NAIP was significantly increased (p=0.04) in clinical samples of prostate cancer from patients receiving ADT. Expression of NAIP may be associated with enhanced survival of prostate cancer in response to castration.Cancer letters 06/2010; 292(2):176-85. · 4.86 Impact Factor