Structural and Mechanistic Bases of Nuclear Calcium Signaling in Human Pluripotent Stem Cell-Derived Ventricular Cardiomyocytes

Figure 5

Expression of parvalbumin (PV) and its mutated form tagged with nuclear localization sequence (NLS) or nuclear export signal (NES). (a) Confocal imaging showed correct localization of PV fusion proteins. Scale . (b) Western blot showing PV fusion proteins could be detected. (c) Cytosol-located PV expression (PV-NES for cytosolic Ca²⁺ buffering) dramatically diminished both cytosolic (upper) and nuclear (lower) Ca²⁺ transient during electrical pacing while nuclear PV expression only decreased the transient amplitude in nuclei without affecting cytosolic transient amplitude. PV-NLS-CD, the mutated form of PV, expression slightly, but not significantly, decreased nuclear Ca²⁺ transient amplitude. cells, (). (d) The effects of nuclear and cytosolic Ca²⁺ buffering on contractile force of hv-CMTs. tissues, . Scale . (e) TUNEL staining in hESC-VCMs showing hESC-VCMs treated with 100 μM H₂O₂ for 1 hour. PV-NES expression caused a lower percentage of TUNEL-positive cells during H₂O₂ treatment compared to control (). Analysis was performed by 7 captures containing 150-200 cells. (f) During hypoxic condition (1% O₂, 8 hours), PV-NES expression reduced the percentage of TUNEL-positive cells compared to control (). Analysis was performed by 3-5 captures containing 150-200 cells.

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