PKC-Mediated Orai1 Channel Phosphorylation Modulates Ca2+ Signaling in HeLa Cells

Development and therapeutic implications of small molecular inhibitors that target calcium-related channels in tumor treatment

Calcium ion dysregulation exerts profound effects on various physiological activities such as tumor proliferation, migration, and drug resistance. Calcium-related channels play a regulatory role in maintaining calcium ion homeostasis, with most channels being highly expressed in tumor cells. Additionally, these channels serve as potential drug targets for the development of antitumor medications. In this review, we first discuss the current research status of these pathways, examining how they modulate various tumor functions such as epithelial-mesenchymal transition (EMT), metabolism, and drug resistance. Simultaneously, we summarize the recent progress in the study of novel small-molecule drugs over the past 5 years and their current status.

[Research advances in genetic polymorphisms in Kawasaki disease]

Kawasaki disease (KD) is a systemic inflammatory vascular disorder that predominantly affects children and is the leading cause of acquired heart disease in children. Although the etiology of this disease remains unclear, genome-wide association and genome-wide linkage studies have shown that some susceptible genes and chromosomal regions are associated with the development and progression of KD. With the advancement of high-throughput DNA sequencing techniques, more and more genomic information related to KD is being discovered. Understanding the genes involved in the pathogenesis of KD may provide novel insights into the diagnosis and treatment of KD. By analyzing related articles and summarizing related research advances, this article mainly discusses the T cell activation-enhancing genes that have been confirmed to be closely associated with the development and progression of KD and reveals their association with the pathogenesis of KD and coronary artery lesions.

Kinetics of the thapsigargin-induced Ca2+ mobilisation: A quantitative analysis in the HEK-293 cell line

Thapsigargin (TG) inhibits the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) pump and, when applied acutely, it initiates a Ca2+ mobilisation that begins with the loss of Ca2+ from the endoplasmic reticulum (ER) and culminates with store-operated Ca2+ entry (SOCE) from the extracellular space. Using the popular model cell line HEK-293, we quantified TG-induced changes in cytosolic and ER Ca2+ levels using FURA-2 and the FRET-based ER Ca2+ sensor D1ER, respectively. Our analysis predicts an ER Ca2+ leak of 5–6 µM⋅s−1 for the typical basal ER Ca2+ level of 335–407 µM in HEK-293 cells. The resulting cytosolic Ca2+ transients reached peak amplitudes of 0.6–1.0 µM in the absence of external Ca2+ and were amplified by SOCE that amounted to 28–30 nM⋅s−1 in 1 mM external Ca2+. Additionally, cytosolic Ca2+ transients were shaped by a Ca2+ clearance of 10–13 nM⋅s−1. Using puromycin (PURO), which enhances the ER Ca2+ leak, we show that TG-induced cytosolic Ca2+ transients are directly related to ER Ca2+ levels and to the ER Ca2+ leak. A one-compartment model incorporating ER Ca2+ leak and cytosolic Ca2+ clearance accounted satisfactorily for the basic features of TG-induced Ca2+ transients and underpinned the rule that an increase in amplitude associated with shortening of TG-induced cytosolic Ca2+ transients most likely reflects an increase in ER Ca2+ leak.

Role of Orai-family channels in the activation and regulation of transcriptional activity

Store operated Ca²⁺ entry (SOCE) is a cornerstone for the maintenance of intracellular Ca²⁺ homeostasis and the regulation of a variety of cellular functions. SOCE is mediated by STIM and Orai proteins following the activation of inositol 1,4,5-trisphosphate receptors. Then, a reduction of the endoplasmic reticulum intraluminal Ca²⁺ concentration is sensed by STIM proteins, which undergo a conformational change and activate plasma membrane Ca²⁺ channels comprised by Orai proteins. STIM1/Orai-mediated Ca²⁺ signals are finely regulated and modulate the activity of different transcription factors, including certain isoforms of the nuclear factor of activated T-cells, the cAMP-response element binding protein, the nuclear factor κ-light chain-enhancer of activated B cells, c-fos, and c-myc. These transcription factors associate SOCE with a plethora of signaling events and cellular functions. Here we provide an overview of the current knowledge about the role of Orai channels in the regulation of transcription factors through Ca²⁺ -dependent signaling pathways.