Molecular and functional characterization of a novel splice variant of ANKHD1 that lacks the KH domain and its role in cell survival and apoptosisc

Abstract

Multiple ankyrin repeat motif‐containing proteins play an important role in protein–protein interactions. ANKHD1 proteins are known to possess multiple ankyrin repeat domains and a single KH domain with no known function. Using yeast two‐hybrid system analysis, we identified a novel splice variant of ANKHD1. This splice variant of ANKHD1, which we designated as HIV‐1 Vpr‐binding ankyrin repeat protein (VBARP), does not contain the signature KH domain, and codes for only a single ankyrin repeat motif. We characterized VBARP by molecular and functional analysis, revealing that VBARP is ubiquitously expressed in different tissues as well as cell lines of different lineage. In addition, blast searches indicated that orthologs and homologs to VBARP exist in different phyla, suggesting that VBARP might be evolutionarily conserved, and thus may be involved in basic cellular function(s). Furthermore, biochemical analysis revealed the presence of two VBARP isoforms coding for 69 and 49 kDa polypeptides, respectively, that are primarily localized in the cytoplasm. Functional analysis using short interfering RNA approaches indicate that this gene product is essential for cell survival through its regulation of caspases. Taken together, these results indicate that VBARP is a novel splice variant of ANKHD1 and may play a role in cellular apoptosis (antiapoptotic) and cell survival pathway(s).

Long-term outdoor air pollution and DNA methylation in circulating monocytes: results from the Multi-Ethnic Study of Atherosclerosis (MESA)

“…ANKHD1 contains multiple ankyrin repeats [50], which mediate protein-protein interactions and have been found in proteins involved in various cellular functions including cell-cell signaling, cytoskeleton integrity, cell cycle control, transcriptional regulation, and inflammatory response [51]. The role that ANKHD1 plays in air pollution-related disease is unclear, but the presence of ankyrin repeats suggests that ANKHD1 may play an important cellular function.…”

Intron retention generates ANKRD1 splice variants that are co-regulated with the main transcript in normal and failing myocardium

“…However, ankrd1 augmented expression can represent an adaptive response of the myocardium to stress both during development and various heart insults . Expression of several ankyrin repeat proteins was found to be associated with cell survival (Miles et al, 2005). In this regard, forced expression of normally sized ankrd1 in rat embryonic cardiomyocytes (Han et al, 2005) and human microvascular endothelial cells (Samaras et al, 2007) increases their resistance to Dox-induced stress/apoptosis which correlates with a decrease in caspase-3 activity.…”

The Role of Vpr in the Regulation of HIV-1 Gene Expression

“…In addition, expression of Vpr can induce apoptosis through a variety of mechanisms. [31][32][33][34][35][36][37] In one study, suppression of NFkB activity through the induction of IkB was linked to Vpr-mediated apoptosis. 38 In other studies, induction of apoptosis by Vpr was attributed to rapid dissipation of the mitochondrial transmembrane potential, association of Vpr with adenine nucleotide translocator, release of cytochrome c, and activation of caspase-3.…”