TMEM87a/Elkin1, a component of a novel mechanoelectrical transduction pathway, modulates melanoma adhesion and migration

Abstract

37Mechanoelectrical transduction is a cellular signalling pathway where physical stimuli are 38 converted into electro-chemical signals by mechanically activated ion channels. We describe 39 here the presence of mechanically activated currents in melanoma cells that are dependent on 40 TMEM87a, which we have renamed Elkin1. Heterologous expression of this protein in 41 PIEZO1-deficient cells, that exhibit no baseline mechanosensitivity, is sufficient to 42 reconstitute mechanically activated currents. Melanoma cells lacking functional Elkin1 43 exhibit defective mechanoelectrical transduction, decreased motility and increased 44 dissociation from organotypic spheroids. By analysing cell adhesion properties, we 45 demonstrate that Elkin1 deletion is associated with increased cell-substrate adhesion and 46 decreased homotypic cell-cell adhesion strength. We therefore conclude that Elkin1 supports 47 a PIEZO1-independent mechanoelectrical transduction pathway and modulates cellular 48 adhesions and regulates melanoma cell migration and cell-cell interactions. 49 50 130 occurred within the stimulus range, allowing us to use a Boltzmann sigmoidal fit to determine 131 the MA current sensitivity. Half-maximal activation of MA currents was seen with 132 approximately 18 nm of substrate deflection (Effective deflection ED50; standard error = 133 20.5 nm). These data indicate a correlation between migratory properties and the MA current 134 sensitivity to deflections applied at cell-substrate contact points. The robust MA current 135 activation observed in cells cultured on LM511 also provided an excellent system to 136 investigate the molecules required for this mechanoelectrical transduction. 137 5 138 157 1999), indicating that neither likely mediates the deflection-evoked currents in WM266-4 158 cells (Figure 1-figure supplement 2). We then examined the proteomics data for proteins of 159 unknown function with 4 or more predicted transmembrane (TM) domains. We prioritised 160 the investigation of Elkin1 due to its expression in melanoma cells but not healthy 161 melanocytes, its expression in additional mechanosensitive cells (Alveolar Type II cells) and 162 its upregulation in additional human cancers (Human Protein Atlas (Uhlén et al., 2005) 163 available from www.proteinatlas.org). We generated miRNA constructs targeting Elkin1 and 164 found that knockdown of Elkin1 transcript resulted in a dramatic reduction in MA currents to 165 deflections up to 1000 nm (Figure 2A,B). These data suggested that Elkin1 contributes to 166 MA currents in melanoma cells. 167 168 Three human isoforms (representing splice variants) of Elkin1 have been identified: isoforms 169 1 and 3 (555 and 494 aa respectively), contain 6 predicted TM domains (Figure 2C). Isoform 170 2 (181 aa) does not contain any predicted TM domains and was not examined in this study.171 6We cloned hsElkin1-iso1 and hsElkin1-iso3 from WM266-4 cDNA and generated C-terminal 172 GFP fusion constructs. We confirmed the plasma membrane localisation of these two 17...

Innocuous pressure sensation requires A-type afferents but not functional ΡΙΕΖΟ2 channels in humans

“…The ability of patients with ΡΙΕΖΟ2 Deficiency Syndrome to sense innocuous pressure exposes the existence of an additional type of mechanosensation that also does not require ΡΙΕΖΟ2. Recently, several genes have been proposed to function as mechanosensitive ion channels [39][40][41][42] and await evaluation of their in vivo roles in pressure sensation.…”

TMEM120A/TACAN inhibits mechanically activated Piezo2 channels

“…Piezo2 is not the only mechanically activated channel in DRG neurons, and it is not the sole sensor responsible for all aspects of somatosensory touch and mechanical pain (Kefauver et al, 2020). Several novel putative mechanically activated channels have been identified in recent years, including Tentonin3 (TMEM150C) (Hong et al, 2016), Elkin1 (TMEM87A) (Patkunarajah et al, 2020), OSCAs (TMEM63) (Murthy et al, 2018a) and TACAN (TMEM120A) (Beaulieu-Laroche et al, 2020). The physiological roles of these novel putative mechanically activated channels is not very well understood.…”

Spatiotemporal dynamics of PIEZO1 localization controls keratinocyte migration during wound healing

“…While mechanically-activated ion channels were proposed to contribute to Ca 2+ signaling in single cell migration in vitro as early as twenty years ago (J. Lee et al 1999;Doyle, Marganski, and Lee 2004;Wei et al 2009;Tsai and Meyer 2012;Patkunarajah et al 2020), many important questions have remained unanswered, including those related to channel identity, functional effects in collective cell migration and physiological contribution during wound healing. We provide evidence for PIEZO1's involvement in cellular retraction events in single cells as well as in collective cell migration during keratinocyte re-epithelialization.…”