Identification, expression and characterization of rat isoforms of the serum response factor (SRF) coactivator MKL1

Ishikawa, Mitsuru; Shiota, Jun; Ishibashi, Yuta; Hakamata, Tomoyuki; Shoji, Shizuku; Tsuda, Masashi; Shirao, Tomoaki; Sekino, Yuko; Ohtsuka, Toshihisa; Baraban, Jay M.; Tabuchi, Akiko

doi:10.1016/j.fob.2013.09.001

Cited by 12 publications

(18 citation statements)

References 17 publications

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“…Together, the opposing roles of S33 and S98 phosphorylation potentially allow fine tuning both of the basal levels of nuclear MRTF-A in resting cells, and the kinetics with which the system can return to its initial state following signalling. MRTF-A and MRTF-B express tissue-specific evolutionarily conserved N-terminal isoforms ( Ishikawa et al, 2013 ), that contain both NES1 and the ERK docking sites required for effective S98 phosphorylation ( Figure 8B ). This suggests that coordination of MRTF NES1 activity and S98 phosphorylation is biologically significant, but the biological context for this remains to be determined.…”

Section: Discussionmentioning

confidence: 99%

Phosphorylation acts positively and negatively to regulate MRTF-A subcellular localisation and activity

Panayiotou

Miralles

Pawłowski

et al. 2016

eLife

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The myocardin-related transcription factors (MRTF-A and MRTF-B) regulate cytoskeletal genes through their partner transcription factor SRF. The MRTFs bind G-actin, and signal-regulated changes in cellular G-actin concentration control their nuclear accumulation. The MRTFs also undergo Rho- and ERK-dependent phosphorylation, but the function of MRTF phosphorylation, and the elements and signals involved in MRTF-A nuclear export are largely unexplored. We show that Rho-dependent MRTF-A phosphorylation reflects relief from an inhibitory function of nuclear actin. We map multiple sites of serum-induced phosphorylation, most of which are S/T-P motifs and show that S/T-P phosphorylation is required for transcriptional activation. ERK-mediated S98 phosphorylation inhibits assembly of G-actin complexes on the MRTF-A regulatory RPEL domain, promoting nuclear import. In contrast, S33 phosphorylation potentiates the activity of an autonomous Crm1-dependent N-terminal NES, which cooperates with five other NES elements to exclude MRTF-A from the nucleus. Phosphorylation thus plays positive and negative roles in the regulation of MRTF-A.DOI: http://dx.doi.org/10.7554/eLife.15460.001

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Section: Discussionmentioning

confidence: 99%

Phosphorylation acts positively and negatively to regulate MRTF-A subcellular localisation and activity

Panayiotou

Miralles

Pawłowski

et al. 2016

eLife

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“…Culture conditions and reagents for dissociating cortical cells were previously described 32 , 33 . Half of the medium was replaced every 3 days.…”

Section: Methodsmentioning

confidence: 99%

“…Immunostaining methods of NIH3T3 cells and cortical cultures were performed as previously described 27 , 32 , 33 .…”

Section: Methodsmentioning

confidence: 99%

Synaptic localisation of SRF coactivators, MKL1 and MKL2, and their role in dendritic spine morphology

Kaneda

Sakagami

Hida

et al. 2018

Sci Rep

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The megakaryoblastic leukaemia (MKL) family are serum response factor (SRF) coactivators, which are highly expressed in the brain. Accordingly, MKL plays important roles in dendritic morphology, neuronal migration, and brain development. Further, nucleotide substitutions in the MKL1 and MKL2 genes are found in patients with schizophrenia and autism spectrum disorder, respectively. Thus, studies on the precise synaptic localisation and function of MKL in neurons are warranted. In this study, we generated and tested new antibodies that specifically recognise endogenously expressed MKL1 and MKL2 proteins in neurons. Using these reagents, we biochemically and immunocytochemically show that MKL1 and MKL2 are localised at synapses. Furthermore, shRNA experiments revealed that postsynaptic deletion of MKL1 or MKL2 reduced the percentage of mushroom- or stubby-type spines in cultured neurons. Taken together, our findings suggest that MKL1 and MKL2 are present at synapses and involved in dendritic spine maturation. This study may, at least in part, contribute to better understanding of the molecular mechanisms underlying MKL-mediated synaptic plasticity and neurological disorders.

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“…) and demonstrated that MKL1 isoforms differentially regulate dendritic complexity (Ishikawa et al . , ). In addition to the physiological roles of MKL in neurons, neuropathological features of MKL have been reported, such as single nucleotide polymorphisms of the MKL1 gene in patients with schizophrenia (Luo et al .…”

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confidence: 99%

“…MKL is an important regulator of neuronal morphology (Kalita et al 2012;Shiota et al 2006;Ishikawa et al 2010;O'Sullivan et al 2010;Mokalled et al 2010). Our previous studies determined the structure of disordered RPEL motifs in MKL1 (Mizuguchi et al 2014) and demonstrated that MKL1 isoforms differentially regulate dendritic complexity (Ishikawa et al 2013. In addition to the physiological roles of MKL in neurons, neuropathological features of MKL have been reported, such as single nucleotide polymorphisms of the MKL1 gene in patients with schizophrenia (Luo et al 2015) and the MKL2 mutation as a possible causative candidate for autistic spectrum disorder (Holt et al 2010;Neale et al 2012).…”

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confidence: 99%

Involvement of SRF coactivator MKL2 in BDNF‐mediated activation of the synaptic activity‐responsive element in the Arc gene

Kikuchi

Ihara

Tanabe

et al. 2018

Journal of Neurochemistry

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The expression of immediate early genes (IEGs) is thought to be an essential molecular basis of neuronal plasticity for higher brain function. Many IEGs contain serum response element in their transcriptional regulatory regions and their expression is controlled by serum response factor (SRF). SRF is known to play a role in concert with transcriptional cofactors. However, little is known about how SRF cofactors regulate IEG expression during the process of neuronal plasticity. We hypothesized that one of the SRF‐regulated neuronal IEGs, activity‐regulated cytoskeleton‐associated protein (Arc; also termed Arg3.1), is regulated by an SRF coactivator, megakaryoblastic leukemia (MKL). To test this hypothesis, we initially investigated which binding site of the transcription factor or SRF cofactor contributes to brain‐derived neurotrophic factor (BDNF)‐induced Arc gene transcription in cultured cortical neurons using transfection and reporter assays. We found that BDNF caused robust induction of Arc gene transcription through a cAMP response element, binding site of myocyte enhancer factor 2, and binding site of SRF in an Arc enhancer, the synaptic activity‐responsive element (SARE). Regardless of the requirement for the SRF‐binding site, the binding site of a ternary complex factor, another SRF cofactor, did not affect BDNF‐mediated Arc gene transcription. In contrast, chromatin immunoprecipitation revealed occupation of MKL at the SARE. Furthermore, knockdown of MKL2, but not MKL1, significantly decreased BDNF‐mediated activation of the SARE. Taken together, these findings suggest a novel mechanism by which MKL2 controls the Arc SARE in response to BDNF stimulation.

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Identification, expression and characterization of rat isoforms of the serum response factor (SRF) coactivator MKL1

Cited by 12 publications

References 17 publications

Phosphorylation acts positively and negatively to regulate MRTF-A subcellular localisation and activity

Phosphorylation acts positively and negatively to regulate MRTF-A subcellular localisation and activity

Synaptic localisation of SRF coactivators, MKL1 and MKL2, and their role in dendritic spine morphology

Involvement of SRF coactivator MKL2 in BDNF‐mediated activation of the synaptic activity‐responsive element in the Arc gene

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