Activation of M-calpain (calpain II) by Epidermal Growth Factor is Limited by Protein Kinase A Phosphorylation of M-calpain
Overview
Affiliations
We have shown previously that the ELR-negative CXC chemokines interferon-inducible protein 10, monokine induced by gamma interferon, and platelet factor 4 inhibit epidermal growth factor (EGF)-induced m-calpain activation and thereby EGF-induced fibroblast cell motility (H. Shiraha, A. Glading, K. Gupta, and A. Wells, J. Cell Biol. 146:243-253, 1999). However, how this cross attenuation could be accomplished remained unknown since the molecular basis of physiological m-calpain regulation is unknown. As the initial operative attenuation signal from the CXCR3 receptor was cyclic AMP (cAMP), we verified that this second messenger blocked EGF-induced motility of fibroblasts (55% +/- 4.5% inhibition) by preventing rear release during active locomotion. EGF-induced calpain activation was inhibited by cAMP activation of protein kinase A (PKA), as the PKA inhibitors H-89 and Rp-8Br-cAMPS abrogated cAMP inhibition of both motility and calpain activation. We hypothesized that PKA might negatively modulate m-calpain in an unexpected manner by directly phosphorylating m-calpain. A mutant human large subunit of m-calpain was genetically engineered to negate a putative PKA consensus sequence in the regulatory domain III (ST369/370AA) and was expressed in NR6WT mouse fibroblasts to represent about 30% of total m-calpain in these cells. This construct was not phosphorylated by PKA in vitro while a wild-type construct was, providing proof of the principle that m-calpain can be directly phosphorylated by PKA at this site. cAMP suppressed EGF-induced calpain activity of cells overexpressing a control wild-type human m-calpain (83% +/- 3.7% inhibition) but only marginally suppressed that of cells expressing the PKA-resistant mutant human m-calpain (25% +/- 5.5% inhibition). The EGF-induced motility of the cells expressing the PKA-resistant mutant also was not inhibited by cAMP. Structural modeling revealed that new constraints resulting from phosphorylation at serine 369 would restrict domain movement and help "freeze" m-calpain in an inactive state. These data point to a novel mechanism of negative control of calpain activation, direct phosphorylation by PKA.
The role of calcium-calpain pathway in hyperthermia.
Enomoto A, Fukasawa T Front Mol Med. 2024; 2:1005258.
PMID: 39086981 PMC: 11285567. DOI: 10.3389/fmmed.2022.1005258.
Langlois B, Martin J, Schneider C, Hachet C, Terryn C, Rioult D Front Oncol. 2022; 12:981927.
PMID: 36052226 PMC: 9424861. DOI: 10.3389/fonc.2022.981927.
The Critical Role of Calpain in Cell Proliferation.
Kovacs L, Su Y J Biomol Res Ther. 2021; 3(3).
PMID: 34414019 PMC: 8373195. DOI: 10.4172/2167-7956.1000112.
Kelley E, Cross T, Snyder E, McDonald C, Hoffman E, Bello L Respir Res. 2019; 20(1):221.
PMID: 31619245 PMC: 6796481. DOI: 10.1186/s12931-019-1200-1.
PFKFB3 in Smooth Muscle Promotes Vascular Remodeling in Pulmonary Arterial Hypertension.
Kovacs L, Cao Y, Han W, Meadows L, Kovacs-Kasa A, Kondrikov D Am J Respir Crit Care Med. 2019; 200(5):617-627.
PMID: 30817168 PMC: 6727156. DOI: 10.1164/rccm.201812-2290OC.