Inhibition of glutaminyl cyclase attenuates cell migration modulated by monocyte chemoattractant proteins

Abstract

QC (glutaminyl cyclase) catalyses the formation of N-terminal pGlu (pyroglutamate) in peptides and proteins. pGlu formation in chemoattractants may participate in the regulation of macrophage activation and migration. However, a clear molecular mechanism for the regulation is lacking. The present study examines the role of QC-mediated pGlu formation on MCPs (monocyte chemoattractant proteins) in inflammation. We demonstrated in vitro the pGlu formation on MCPs by QC using MS. A potent QC inhibitor, PBD150, significantly reduced the N-terminal uncyclized-MCP-stimulated monocyte migration, whereas pGlu-containing MCP-induced cell migration was unaffected. QC small interfering RNA revealed a similar inhibitory effect. Lastly, we demonstrated that inhibiting QC can attenuate cell migration by lipopolysaccharide. These results strongly suggest that QC-catalysed N-terminal pGlu formation of MCPs is required for monocyte migration and provide new insights into the role of QC in the inflammation process. Our results also suggest that QC could be a drug target for some inflammatory disorders.

Role of glutaminyl cyclases in thyroid carcinomas

“…In contrast to DP4 and aminopeptidase P, the mature pE-modified N-terminus of CCL2 is not protected against MMP1 cleavage (McQuibban et al 2002, Cynis et al 2011. Furthermore, inhibition of QC activity by a competitive inhibitor or by RNAi suppressed monocytic cell migration (Cynis et al 2011, Chen et al 2012. Hence, the prevention of pE-formation has the potential to enhance chemokine degradation by suppression of N-terminal maturation and, thereby, opening alternative degradation pathway and this impairs the bioactivity of CCL2.…”

“…Recently, others and we described that the pE protein modification is an important posttranslational step in CCL2 maturation (Cynis et al 2011, Chen et al 2012. Owing to the cyclization of the N-terminal CCL2 glutaminyl precursor into pE, the positive charge of the N-terminus is lost resulting in resistance against cleavage by aminopeptidases such as dipeptidyl peptidase 4/CD26, which is highly expressed in FTC and PTC (Kehlen et al 2003).…”

“…Interestingly, the oncogenic fusion protein RET/PTC expressed in PTC activates the transcription factor NF-kB and induces CCL2 gene expression (Russell et al 2003, Neely et al 2011. Recently, others and we have shown that the chemotactic activity of CCL2 depends on a modified N-terminus of the polypeptide, particularly the formation of a pyroglutamate (pE)-residue protecting against proteolytic degradation in vivo (Cynis et al 2011, Chen et al 2012. The formation of the N-terminal pE-residue is an important maturation step during synthesis and secretion of not only CCL2 but also hormones such as thyreotropin-releasing hormone and GNRH (Goren et al 1977, Abraham & Podell 1981, Awade et al 1994.…”

Linked Production of Pyroglutamate-Modified Proteins via Self-Cleavage of Fusion Tags with TEV Protease and Autonomous N-Terminal Cyclization with Glutaminyl Cyclase In Vivo

“…Up to now, it is still unclear whether the cyclization reaction occurs post-translationally or co-translationally. Several papers reported that the conversion of glutaminyl peptides to their respective pyroglutamyl peptides can be accomplished by adding QC in vitro [24], [25]. However, a recent report described that pGlu formation likely occurs in the initial stage of protein folding in vivo , specifically before the formation of structured intermediates [26], thus supporting a co-translational cyclization reaction.…”

Can Small Molecule Inhibitors of Glutaminyl Cyclase Be Used as a Therapeutic for Alzheimer'S Disease?

“…And the pE-CCL2 levels in cerebrospinal fluid correlates with the faster cognitive decline in prodromal AD patients. Accordingly, inhibiting the generation of pE-CCL2 is believed to be a promising new approach for the prevention and treatment of neuroinflammation at the beginning of AD [9].…”