The Effector Domain of MARCKS Is a Nuclear Localization Signal that Regulates Cellular PIP2 Levels and Nuclear PIP2 Localization

Abstract

Translocation to the nucleus of diacylglycerol kinase (DGK)– ζ is dependent on a sequence homologous to the effector domain of Myristoylated Alanine Rich C-Kinase Substrate (MARCKS). These data would suggest that MARCKS could also localize to the nucleus. A single report demonstrated immunofluorescence staining of MARCKS in the nucleus; however, further experimental evidence confirming the specific domain responsible for this localization has not been reported. Here, we report that MARCKS is present in the nucleus in GBM cell lines. We then over-expressed wild-type MARCKS (WT) and MARCKS with the effector domain deleted (ΔED), both tagged with V5-epitope in a GBM cell line with low endogenous MARCKS expression (U87). We found that MARCKS-WT localized to the nucleus, while the MARCKS construct without the effector domain remained in the cytoplasm. We also found that over-expression of MARCKS-WT resulted in a significant increase in total cellular phosphatidyl-inositol (4,5) bisphosphate (PIP2) levels, consistent with prior evidence that MARCKS can regulate PIP2 levels. We also found increased staining for PIP2 in the nucleus with MARCKS-WT over-expression compared to MARCKS ΔED by immunofluorescence. Interestingly, we observed MARCKS and PIP2 co-localization in the nucleus. Lastly, we found changes in gene expression when MARCKS was not present in the nucleus (MARCKS ΔED). These data indicate that the MARCKS effector domain can function as a nuclear localization signal and that this sequence is critical for the ability of MARCKS to regulate PIP2 levels, nuclear localization, and gene expression. These data suggests a novel role for MARCKS in regulating nuclear functions such as gene expression.

Mapping the Spatial Proteome of Metastatic Cells in Colorectal Cancer

“…This interesting finding supports a multifunctional role for this protein in chromatin organization and transcriptional control in cancer metastatic cells . We also confirm the recent nuclear assignment of MARCKS and its potential function in regulation of gene expression, indicating another dual localization for this adhesion protein.…”

Upregulation of MARCKS in kidney cancer and its potential as a therapeutic target

“…Indeed, several studies have shown a functional role of the MARCKS PSD in PIP2 sequestration and accumulation though its binding to PIP2 molecules. 43,51,52 Therefore, there is a possibility that MARCKS in its unphosphorylated state (membrane-bound) reduces the availability of PIP2 to other molecules such as PI3K, 42 thereby inactivating the PI3K/AKT pathway, as MPS did. A study on the role of MARCKS as a tumor suppressor in glioma is consistent with this proposition.…”

Differential expression, localization and activity of MARCKS between mantle cell lymphoma and chronic lymphocytic leukemia

“…As MARCKS was previously showed either bound to the cell membrane or reside in the cytosol, or alternatively become transmitted to nuclei via PIP2, 11 we investigated subcellular localization of MARCKS using immunofluorescence (IF). Indeed, the overall signal between MCL and CLL was markedly higher in MCL.…”