TRPM7 triggers Ca2+ sparks and invadosome formation in neuroblastoma cells

Abstract

Cell migration depends on the dynamic formation and turnover of cell adhesions and is tightly controlled by actomyosin contractility and local Ca2+ signals. The divalent cation channel TRPM7 (Transient Receptor Potential cation channel, subfamily Melastatin, member 7) has recently received much attention as a regulator of cell adhesion, migration and (localized) Ca2+ signaling. Overexpression and knockdown of TRPM7 affects actomyosin contractility and the formation of cell adhesions such as invadosomes and focal adhesions, but the role of TRPM7-mediated Ca2+ signals herein is currently not understood. Using Total Internal Reflection Fluorescence (TIRF) Ca2+ fluorometry and a novel automated analysis routine we have addressed the role of Ca2+ in the control of invadosome dynamics in N1E-115 mouse neuroblastoma cells. We find that TRPM7 promotes the formation of highly repetitive and localized Ca2+ microdomains or “Ca2+ sparking hotspots” at the ventral plasma membrane. Ca2+ sparking appears strictly dependent on extracellular Ca2+ and is abolished by TRPM7 channel inhibitors such as waixenicin-A. TRPM7 inhibition also induces invadosome dissolution. However, invadosome formation is (functionally and spatially) dissociated from TRPM7-mediated Ca2+ sparks. Rather, our data indicate that TRPM7 affects actomyosin contractility and invadosome formation independent of Ca2+ influx.

Expression and Contributions of TRPM7 and KCa2.3/SK3 Channels to the Increased Migration and Invasion of Microglia in Anti-Inflammatory Activation States

“…It can interact with cytoskeletal components [78], [79] to modulate actomyosin contractility that is required for cell migration [80]. Over-expressing TRPM7 in a neuroblastoma cell line facilitated cell adhesion and formation of podosomes [78] and invadosomes [77], and inhibiting TRPM7 reduced migration of activated T cells [81]. TRPM7 whole-cell currents were of similar amplitude in unstimulated microglia and after treatment with LPS or a phorbol ester [19], as well as IL4 or IL10 (present study); however, the channel is regulated by several mechanisms that might affect the current in intact cells.…”

The Transient Receptor Potential Melastatin 7 Channel Regulates Pancreatic Cancer Cell Invasion through the Hsp90α/uPA/MMP2 pathway

“…Among TRP channels, the transient receptor potential melastatin related 7 (TRPM7) channel is a Ca 2+ /Mg 2+ channel fused with a functional kinase domain that belongs to the α-kinase family [13], [14]. We and others showed that TRPM7 is involved in migration and/or invasion of epidermal cancer cells including neuroblastoma [15], [16], glioblastoma [17], breast cancer [18], [19], nasopharynx cancer [20], [21], lung cancer [22], prostate cancer [23], and PDAC [24], [25]. Importantly, TRPM7 is required for breast cancer metastasis formation in mouse xenograft, and high channel expression is an independent marker of poor outcome in breast cancer patients [26].…”

Reactive astrocytes in multiple sclerosis impair neuronal outgrowth through TRPM7‐mediated chondroitin sulfate proteoglycan production

“…Ca 2+ recordings were performed as described previously (Langeslag, Clark, Moolenaar, van Leeuwen, & Jalink, ; Visser et al, ). In short, cells were grown in 24 wells plate and incubated with Oregon Green 488 BAPTA‐1‐AM (Molecular Probes, USA) followed by further incubation in 2 ml DMEM F/12.…”