Coordinated assembly and disassembly of integrin-mediated focal adhesions (FAs) is essential for cell migration. Many studies have shown that FA disassembly requires Ca2+ influx, however our understanding of this process remains incomplete. Here, we show that Ca2+ influx via STIM1/Orai1 calcium channels, which cluster near FAs, leads to activation of the GTPase Arf5 via the Ca2+-activated GEF IQSec1, and that both IQSec1 and Arf5 activation are essential for adhesion disassembly. We further show that IQSec1 forms a complex with the lipid transfer protein ORP3, and that Ca2+ influx triggers PKC-dependent translocation of this complex to ER/plasma membrane (PM) contact sites adjacent to FAs. In addition to allosterically activating IQSec1, ORP3 also extracts PI4P from the PM, in exchange for phosphatidylcholine. ORP3-mediated lipid exchange is also important for FA turnover. Together, these findings identify a new pathway that links calcium influx to FA turnover during cell migration.

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Thermal and mechanical stress conditions were applied to two model proteins, human growth hormone (hGH) and epidermal growth factor (EGF), to evaluate protein stability during the manufacturing process, focusing on protein secondary structure and aggregation. The samples were analyzed with differential scanning calorimetry (DSC), circular dichroism (CD), and size-exclusion chromatography (SEC). The monomer and aggregation contents were obtained by SEC and the proteins' secondary structure on exposure to thermal stress was evaluated by CD. DSC showed that the transition temperature (T m) of hGH and EGF was 74.43 and 79.11 °C, respectively. The accelerated thermal stress temperature was set at 70 °C. The monomer content of hGH decreased from 97.8 to 82.3 % in response to thermal stress. However, the monomer content of EGF decreased significantly from 33.73 to 5.61 %. The hGH and EGF showed an increase in α-helix content and a decrease in β-sheet (antiparallel and parallel β-sheet). Moreover, the contents changed significantly during the first 1 h and then changed slightly for the remaining time. On the other hand, shaking stress showed that hGH was highly affected compared to EGF. The hGH monomer steadily decreased and only the half the monomer content remained at 3 h. It is suspected that the shaking stress induced hGH adsorption to the gas-liquid interface, which may facilitate protein denaturation. The results indicate that protective excipients might be necessary for inevitable stress conditions during the developmental process. The stability of each protein differed with respect to specific stress conditions. Therefore, an array of complementary analytical methods might be required to evaluate the protein stability.

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