N-terminal nesprin-2 variants regulate β-catenin signalling.
The spatial compartmentalisation of biochemical signalling pathways is essential for cell function. Nesprins are a multi-isomeric family of proteins that have emerged as signalling scaffolds, herein, we investigate the localisation and function of novel nesprin-2 N-terminal variants. We show that these nesprin-2 variants display cell specific distribution and reside in both the cytoplasm and nucleus. Immunofluorescence microscopy revealed that nesprin-2 N-terminal variants colocalised with β-catenin at cell-cell junctions in U2OS cells. Calcium switch assays demonstrated that nesprin-2 and β-catenin are lost from cell-cell junctions in low calcium conditions whereas emerin localisation at the NE remained unaltered, furthermore, an N-terminal fragment of nesprin-2 was sufficient for cell-cell junction localisation and interacted with β-catenin. Disruption of these N-terminal nesprin-2 variants, using siRNA depletion resulted in loss of β-catenin from cell-cell junctions, nuclear accumulation of active β-catenin and augmented β-catenin transcriptional activity. Importantly, we show that U2OS cells lack nesprin-2 giant, suggesting that the N-terminal nesprin-2 variants regulate β-catenin signalling independently of the NE. Together, these data identify N-terminal nesprin-2 variants as novel regulators of β-catenin signalling that tether β-catenin to cell-cell contacts to inhibit β-catenin transcriptional activity.
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Qiuping
Q
Zhang
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Rose-Marie
RM
Minaisah
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Elisa
E
Ferraro
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Chen
C
Li
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Lauren J
LJ
Porter
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Can
C
Zhou
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Fang
F
Gao
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Junyi
J
Zhang
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Dipen
D
Rajgor
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Flavia
F
Autore
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK.
Catherine M
CM
Shanahan
British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College, SE5 9NU London, UK. Electronic address: derek.warren@kcl.ac.uk.
Derek T
DT
Warren
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D015203:Reproducibility of Results; D015398:Signal Transduction; D014158:Transcription, Genetic; D051176:beta Catenin / Q000378:metabolism*
D008565:Membrane Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; C485904:SYNE2 protein, human; D051176:beta Catenin; C092710:emerin
Cell-cell junctions; Nesprin-2; Scaffold protein; Β-catenin