Key result
Overexpression of ERM proteins increased perinuclear actin rim levels by up to 40%, while knockdown of Moesin and Ezrin reduced rim levels by 25% and 50%, respectively, in mouse melanoma cells.
Why the study?
It was not clear how the perinuclear actin rim is coupled with the nuclear envelope.
ERM proteins are part of the mechanism that links actin filaments to the nuclear envelope, supporting perinuclear actin rim formation.
Supports ERM proteins as regulators of nuclear actin in animal models; leaves open translational relevance to human cardiovascular disease.
The interaction of actin filaments with the nuclear envelope is essential for diverse cellular processes, including cell migration, nuclear positioning, and transcriptional control. The main studied mechanism that links F-actin to the nucleus is the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. Recently, the formation of a perinuclear actin rim has been identified in various cell types in response to external force or migration signals. This rim depends on the activation of the actin nucleator Inverted formin 2 (INF2) by calcium influx. However, it is not clear how the rim is coupled with the nuclear envelope. Here we show that the nuclear membrane protein Emerin, which has an actin-binding domain, is not required for the perinuclear actin rim formation. Interestingly, we found that the Ezrin-Radixin-Moesin (ERM) proteins, known to link actin filaments to the cell membrane, are also localized to the nuclear envelope in melanoma cells. Overexpression of ERM proteins increased the perinuclear actin rim levels, while knockdown of ERM proteins led to a reduction in the rim levels. Thus, the ERM proteins appear as part of the mechanism that links actin filaments to the nuclear envelope.
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Fracchia et al. (2025) studied Melanoma (in vitro cell line model). ERM proteins overexpression and knockdown vs. Control cells (siRNA control or non-overexpressing) was evaluated on Intensity of the perinuclear actin rim. Overexpression of ERM proteins increased perinuclear actin rim levels by up to 40%, while knockdown of Moesin and Ezrin reduced rim levels by 25% and 50%, respectively, in mouse melanoma cells.
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