Isoform-specific interactions between meprin metalloproteases and the catalytic subunit of protein kinase A: Significance in acute and chronic kidney injury.

Isoform-specific interactions between meprin metalloproteases and the catalytic subunit of protein kinase A: Significance in acute and chronic kidney injury. Am J Physiol Renal Physiol. 2014 Oct 29;:ajprenal.00167.2014 Authors: Niyitegeka JM, Bastidas AC, Newman RH, Taylor SS, Ongeri EM Abstract Meprins metalloproteases are abundantly expressed in the brush border membranes of kidney proximal tubules. Meprins are implicated in ischemia/reperfusion (IR)-induced renal injury and diabetic nephropathy. The protein kinase A (PKA) signaling pathway modulates extracellular matrix metabolism in diabetic kidneys. The present study evaluated isoform-specific interactions between the catalytic subunit of PKA (PKA C) and meprins. To this end, cytosolic-enriched kidney proteins from meprin αβ double knockout mice, and purified forms of recombinant mouse PKA Cα, Cβ1, and Cβ2, were incubated with activated forms of either homomeric meprin A or meprin B. The cleaved protein products were subjected to SDS-PAGE and analyzed by coomassie staining and Western blot analysis. While meprin A only cleaved PKA Cβ1, meprin B cleaved all three PKA C isoforms. Analysis of the proteolytic fragments by mass spectrometry revealed that meprin A and B cleave the PKA C isoforms at defined sites, resulting in unique cleavage products. Michaelis-Menten enzyme kinetics demonstrated that meprin B-mediated cleavage of PKA Cα occurs at a rate consistent with that of...
Source: Am J Physiol Renal P... - Category: Urology & Nephrology Authors: Tags: Am J Physiol Renal Physiol Source Type: research