Armadillo repeat-containing proteins (ARMCs) are a large family found throughout eukaryotes, which play prominent roles in cell adhesion, signaling and cytoskeletal regulation. The ARMC6 protein is highly conserved in primates, including humans, but to date does not have a clear function beyond initial hints of a link to cancer and telomerase activity. We report here in vitro experiments showing ARMC6 binding to DNA promoter sequences from several cancer-related genes (e.g., EGFR, VEGF and c-MYC), and also to the telomeric RNA repeat (TERRA). ARMC6 binding activity appears to recognize G-quadruplex motifs, which are being increasingly implicated as structure-based protein binding sites in chromosome maintenance and repair. In vivo investigation of ARMC6 function revealed that when this protein is overexpressed in human cell lines, there is different expression of genes connected with oncogenic pathways and those implicated in downstream non-canonical telomerase pathways (e.g., VEGF, hTERT, c-MYC, ESM1, MMP3). ARMC6 is already known to interact with human shelterin protein TRF2 and telomerase. The protein binds G-quadruplex structures and does so preferentially to RNA over DNA. As such, this protein may be an example of how a non-canonical nucleic acid structural motif allows mediation between gene regulation and telomeric chromatin rearrangement pathways.
- MeSH
- DNA vazebné proteiny MeSH
- G-kvadruplexy * MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádory genetika metabolismus MeSH
- promotorové oblasti (genetika) * MeSH
- proteiny s doménou armadillo * metabolismus genetika MeSH
- regulace genové exprese u nádorů MeSH
- RNA metabolismus genetika MeSH
- telomerasa metabolismus genetika MeSH
- telomery * metabolismus MeSH
- transkripční faktory MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
KEY MESSAGE: Arabidopsis and human ARM protein interact with telomerase. Deregulated mRNA levels of DNA repair and ribosomal protein genes in an Arabidopsis arm mutant suggest non-telomeric ARM function. The human homolog ARMC6 interacts with hTRF2. Telomerase maintains telomeres and has proposed non-telomeric functions. We previously identified interaction of the C-terminal domain of Arabidopsis telomerase reverse transcriptase (AtTERT) with an armadillo/β-catenin-like repeat (ARM) containing protein. Here we explore protein-protein interactions of the ARM protein, AtTERT domains, POT1a, TRF-like family and SMH family proteins, and the chromatin remodeling protein CHR19 using bimolecular fluorescence complementation (BiFC), yeast two-hybrid (Y2H) analysis, and co-immunoprecipitation. The ARM protein interacts with both the N- and C-terminal domains of AtTERT in different cellular compartments. ARM interacts with CHR19 and TRF-like I family proteins that also bind AtTERT directly or through interaction with POT1a. The putative human ARM homolog co-precipitates telomerase activity and interacts with hTRF2 protein in vitro. Analysis of Arabidopsis arm mutants shows no obvious changes in telomere length or telomerase activity, suggesting that ARM is not essential for telomere maintenance. The observed interactions with telomerase and Myb-like domain proteins (TRF-like family I) may therefore reflect possible non-telomeric functions. Transcript levels of several DNA repair and ribosomal genes are affected in arm mutants, and ARM, likely in association with other proteins, suppressed expression of XRCC3 and RPSAA promoter constructs in luciferase reporter assays. In conclusion, ARM can participate in non-telomeric functions of telomerase, and can also perform its own telomerase-independent functions.
- MeSH
- Arabidopsis enzymologie genetika MeSH
- holoenzymy MeSH
- lidé MeSH
- proteiny huseníčku genetika metabolismus MeSH
- proteiny s doménou armadillo genetika metabolismus MeSH
- reportérové geny MeSH
- techniky dvojhybridového systému MeSH
- telomerasa genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
