The origin of the expressed retrotransposed gene ACTBL2 and its influence on human melanoma cells’ motility and focal adhesion formation

Abstract

We have recently found that β-actin-like protein 2 (actbl2) forms complexes with gelsolin in human melanoma cells and can polymerize. Phylogenetic and bioinformatic analyses showed that actbl2 has a common origin with two non-muscle actins, which share a separate history from the muscle actins. The actin groups’ divergence started at the beginning of vertebrate evolution, and actbl2 actins are characterized by the largest number of non-conserved amino acid substitutions of all actins. We also discovered that ACTBL2 is expressed at a very low level in several melanoma cell lines, but a small subset of cells exhibited a high ACTBL2 expression. We found that clones with knocked-out ACTBL2 (CR-ACTBL2) or overexpressing actbl2 (OE-ACTBL2) differ from control cells in the invasion, focal adhesion formation, and actin polymerization ratio, as well as in the formation of lamellipodia and stress fibers. Thus, we postulate that actbl2 is the seventh actin isoform and is essential for cell motility.

Gelsolin Contributes to the Motility of A375 Melanoma Cells and This Activity Is Mediated by the Fibrous Extracellular Matrix Protein Profile

“…However, the results from the fluorescein-gelatin assay showed that the cells without GSN, which manifested heavily impaired invasion/3-D migration abilities, formed a higher number of invadopodia, albeit they were less active than in the case of control cells. A higher number of invadopodia was previously observed by us when we studied A375 cells not producing β or γ actin or actbl2 [25,31]. We assume that this phenomenon is a somewhat compensation mechanism activated by those cells with diminished migratory abilities.…”

“…To study the role of GSN in melanoma cells' motility on different ECM proteins, we decided to knockout GSN. For this purpose, we used the CRISPR/Cas9(D10A) system, which we utilized in our previous studies [25,31]. We believe that this was an appropriate approach because non-manipulated A375 cells exhibit a varying level of GSN.…”

“…To study the role of GSN in the motility of A375 cells growing on different ECM proteins, we decided to knockout the GSN using the CRISPR/Cas9(D10A) technique. Previously, with the double nickase system (control double nickase plasmids) coding for non-targeting 20 nt scramble guide RNA sequences, we have obtained three control A375 clones, which we named CTRL KO clones [25,31]. For the purpose of this research, we generated stable A375 clones with GSN knockout using the same double nickase system.…”

Changes in Biomechanical Properties of A375 Cells Due to the Silencing of TMSB4X Expression Are Not Directly Correlated with Alterations in Their Stemness Features

“…Pucciarelli, with colleagues, showed that exposure of cells to hypoxia enhances their heterogeneity [86]. We have recently demonstrated that A375 cells are not homogeneous in terms of expression of ACTBL2, a gene coding for β-actin-like protein 2, which is the seventh actin isoform [87]. We have shown by applying the RNAscope procedure that only subsets of A375 and Hs294T (another melanoma cell line) cells expressed ACTBL2.…”

Axial Scanning Metal‐Induced Energy Transfer Microscopy for Extended Range Nanometer‐Sectioning Cell Imaging

“…[31,32] The thickness of lamellipodium, membrane tension, and the motility of a cell are closely related, and there have been several reports on morphological characteristics of invasive tumor cells. [28,33,34] The correlation between the thickness of lamellipodium at the edge and the motility of a tumor cell is another example of exciting research topics we can quickly investigate with the help of AS-MIET microscopy.…”