Control of TRPM3 Ion Channels by Protein Kinase CK2-Mediated Phosphorylation in Pancreatic β-Cells of the Line INS-1

Abstract

In pancreatic β-cells of the line INS-1, glucose uptake and metabolism induce the openings of Ca2+-permeable TRPM3 channels that contribute to the elevation of the intracellular Ca2+ concentration and the fusion of insulin granules with the plasma membrane. Conversely, glucose-induced Ca2+ signals and insulin release are reduced by the activity of the serine/threonine kinase CK2. Therefore, we hypothesized that TRPM3 channels might be regulated by CK2 phosphorylation. We used recombinant TRPM3α2 proteins, native TRPM3 proteins from INS-1 β-cells, and TRPM3-derived oligopeptides to analyze and localize CK2-dependent phosphorylation of TRPM3 channels. The functional consequences of CK2 phosphorylation upon TRPM3-mediated Ca2+ entry were investigated in Fura-2 Ca2+-imaging experiments. Recombinant TRPM3α2 channels expressed in HEK293 cells displayed enhanced Ca2+ entry in the presence of the CK2 inhibitor CX-4945 and their activity was strongly reduced after CK2 overexpression. TRPM3α2 channels were phosphorylated by CK2 in vitro at serine residue 1172. Accordingly, a TRPM3α2 S1172A mutant displayed enhanced Ca2+ entry. The TRPM3-mediated Ca2+ entry in INS-1 β-cells was also strongly increased in the presence of CX-4945 and reduced after overexpression of CK2. Our study shows that CK2-mediated phosphorylation controls TRPM3 channel activity in INS-1 β-cells.

Bradykinin-Induced Sensitization of Transient Receptor Potential Channel Melastatin 3 Calcium Responses in Mouse Nociceptive Neurons

“…Both TRPA1 and TRPV1 can be phosphorylated and sensitized by calcium–calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC) ( Bonnington and McNaughton, 2003 ; Zhang et al, 2010 ; Wang et al, 2015 ; Patil et al, 2020 ). Since TRPM3 proteins also harbor several potential phosphorylation sites ( Becker et al, 2021 ), we examined the effect of inhibitors of either CaMKII (KN62; 1 μM; Figure 4A ) or PKC (Gö6983; GÖ; 1 μM, Figure 4D ) on TRPM3 sensitization by BK. Interestingly, neither inhibition of CaMKII ( p < 0.001, Mann-Whitney U; Figure 4B ) nor PKC ( p < 0.01, Mann-Whitney U; Figure 4E ) prevented TRPM3 sensitization.…”

Roles of TRPM channels in glioma

“…Several studies have found that [Ca2+] cyt and intracellular Mg2+ ions inhibit the activity of TRPM3 channels. 77 , 91 …”

The Role of Protein Kinase CK2 in Development and Disease Progression: A Critical Review

“…Further, in other circumstances, CK2 can phosphorylate substrates that do not share the consensus sequence, such as serine 392 of p53 or the tyrosine residues of Fpr3 in yeast [ 120 , 121 , 122 ]. Due to the versatility of this enzyme, CK2 activates numerous interacting proteins, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 and transient receptor potential cation channel subfamily M (TRPM) 3 ion channels [ 123 , 124 ]. As CK2 targets many substrates, it has increasingly become a candidate for novel therapeutics, as it is implicated in the progression of many diseases, such as breast and colon cancer [ 23 , 125 , 126 , 127 ].…”