Flightless-I, a gelsolin family member and transcriptional regulator, preferentially binds directly to activated cytosolic CaMK-II

Abstract

In order to evaluate links between Ca2+/calmodulin (CaM)-dependent protein kinase type II (CaMK-II) and cell cycle progression, CaMK-II binding partners were sought in proliferating cells by epitope-tag tandem mass spectrometry. One protein identified was the gelsolin family member, flightless-I (Fli-I). Fli-I is not a CaMK-II substrate, but binds directly and preferentially to constitutively active (T287D) CaMK-II over inactive CaMK-II. Fli-I gradually enters the nucleus upon CaMK-II inhibition and is retained in the cytosol by T287D CaMK-II. CaMK-II inhibition and Fli-I overexpression suppress transcription of β-catenin dependent transcriptional reporters, whereas Fli-I suppression enhances their transcription. These findings support a novel mechanism whereby cytosolic CaMK-II influences β-catenin dependent gene expression through Fli-I. Structured summaryMINT-6603828:delta CaMK-II (uniprotkb:Q6PHZ2) binds (MI:0407) to Flightless-I (uniprotkb:Q9JJ28) by anti bait coimmunoprecipitation (MI:0006)MINT-6603847:delta CaMK-II (uniprotkb:Q6PHZ2) phosphorylates (MI:0217) MAP2 (uniprotkb:P20357) by protein kinase assay (MI:0424)MINT-6603768:beta CaMK-II (uniprotkb:P28652) physically interacts (MI:0218) with Flightless-I (uniprotkb:Q9JJ28) by anti bait coimmunoprecipitation (MI:0006)MINT-6603759, MINT-6603776, MINT-6603786:delta CaMK-II (uniprotkb:Q6PHZ2) physically interacts (MI:0218) with Flightless-I (uniprotkb:Q9JJ28) by anti bait coimmunoprecipitation (MI:0006)MINT-6603724:CaMK-II delta (uniprotkb:Q6PHZ2) physically interacts (MI:0218) with beta 5tubulin (uniprotkb:P99024), beta 2c tubulin (uniprotkb:P68372), alpha 1a tubulin (uniprotkb:P68369), b-Actin (uniprotkb:P60710), Tropomodulin-3 (uniprotkb:Q9JHJ0), Flightless-I (uniprotkb:Q9JJ28), FLAP1 (uniprotkb:Q3UZ39) and FLAP2 (uniprotkb:Q91WK0) by anti tag coimmunoprecipitation (MI:0007).