The rapid activation of cPKCβII by progesterone results in the negative regulation of Ca 2+ influx in human resting T cells

Veronica Hui-Chen Lin; Angela Chien; Eileen Jea Chien

doi:10.1097/JCMA.0000000000000970

The rapid activation of cPKCβII by progesterone results in the negative regulation of Ca 2+ influx in human resting T cells

J Chin Med Assoc. 2023 Oct 1;86(10):885-891. doi: 10.1097/JCMA.0000000000000970. Epub 2023 Jul 27.

Authors

Veronica Hui-Chen Lin¹, Angela Chien², Eileen Jea Chien¹

Affiliations

¹ Department and Institute of Physiology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC.
² Department of Biotechnology, School of Health Technology, Ming Chuan University, Taoyuan, Taiwan, ROC.

PMID: 37496123
DOI: 10.1097/JCMA.0000000000000970

Abstract

Background: Progesterone-stimulated rapid suppression of phytohemagglutinin (PHA)-activated sustained membrane Ca 2+ influx is revealed by Mn 2+ quenching fura-2 fluorescence. Ca 2+ influx suppression results in immunosuppression of T-cell proliferation. Downregulation of protein kinase C (PKC) activity by phorbol 12-myristate 13-acetate (PMA) enhances the PHA-activated increase in sustained intracellular Ca 2+ concentration ([Ca 2+ ] i ) via Ca 2+ influx in T cells. Conventional PKC (cPKC) inhibitors also enhance the [Ca 2+ ] i increase in resting T cells caused by progesterone. This study explores whether cPKC activation by progesterone results in suppression of Ca 2+ influx in resting T cells.

Methods: Progesterone, its analogs (R5020/Org OD 02-0), and plasma membrane-impermeable progesterone-bovine serum albumin conjugate were used to stimulate human resting T cells. Inhibitors and PKC downregulation by PMA were used to investigate whether cPKC affects Ca 2+ influx.

Results: Progesterone and analogs dose-dependently suppressed Ca 2+ influx in T cells. One cPKC inhibitor, Ro318220, attenuated Ca 2+ influx suppression, and enhanced the increase in [Ca 2+ ] i caused by progesterone and analogs. U73122 did not affect Ca 2+ influx suppression but did decrease the [Ca 2+ ] i increase. Ca 2+ influx suppression was not attenuated by the cPKCα/βI isoform-selective inhibitor, Go6976, nevertheless, a cPKCβI/βII isoform-selective inhibitor, LY333531 did. Ca 2+ influx suppression was attenuated by the cPKCβII-specific inhibitor CGP53353. After PKC downregulated by PMA, Ca 2+ influx suppression by progesterone and analogs was almost abolished in parallel with a massive reduction in cPKCβII expression. This suggests cPKCβII activation by progesterone and analogs mediate Ca 2+ influx suppression in resting T cells.

Conclusion: Nongenomic membrane activation of cPKCβII by progesterone causes immunosuppression via negative regulation of Ca 2+ influx into human resting T cells. This prevents resting T-cell activation and proliferation, which protects the fetus from maternal immune attack while decreasing maternal autoimmune disease flare-ups during pregnancy. Thus, cPKCβII modulators might provide a new therapeutic approach to balancing T-cell tolerance and immunity.