Cellular localization and dendritic function of rat isoforms of the SRF coactivator MKL1 in cortical neurons

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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“…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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“…It is highly likely that the phenotype of hematopoiesisspecific inducible Rbm15 KO mice, which lose long-term reconstituting HSC function, is due to loss of m6A RNA as hematopoiesis-specific inducible Mettl3 KO mice also lack functional longterm reconstituting HSCs (84). Whether m6A RNA modification accounts for the published roles of RBM15 in RNA splicing, chromatin remodeling, and nuclear export of RNA is not yet known (82,85). RBPJk (recombination signal binding protein for immunoglobulin kappa J region), a transcription factor critical for Notch signaling (77).…”

Section: Rbm15-mrtfa Fusion Proteinmentioning

confidence: 99%

MRTFA: A critical protein in normal and malignant hematopoiesis and beyond

Reed

Larsuel

Mayday

et al. 2021

Journal of Biological Chemistry

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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%

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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Cellular localization and dendritic function of rat isoforms of the SRF coactivator MKL1 in cortical neurons

Cited by 10 publications

References 11 publications

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

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

MRTFA: A critical protein in normal and malignant hematopoiesis and beyond

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

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