DPP9-gene

DPP9 is the acronym for "dipeptidyl peptidase 9" an enzyme that in humans is encoded by the gene of the same name (DPP9 gene). The DPP9 gene is located on chromosome 19 band 19p13.3. The encoded enzyme protein DPP9 is a serine protease of the DPPIV gene family, which play a role in immune responses. Several transcript variants of the DPP9 gene have been described but not fully characterized.

DPP9 shows a so-called post-proline dipeptidyl aminopeptidase activity, which cleaves Xaa-Pro dipeptides from the N-termini of proteins. Although the activity of this protein resembles that of dipeptidyl peptidase 4 (DPP4), it does not appear to be membrane bound. Thus, DPP9 is expressed primarily intracellularly and can be detected mainly in the cytoplasm, but also in cell membranes and organelles/vesicles (Zapletal E et al. 2017).

DPP9 has been linked to immune regulation, disease pathogenesis and versch. Metabolic processes. Animal experiments have shown that in liver cells DPP9 protein levels are altered by EGF, HGF, insulin or palmitate. These findings suggest possible natural DPP9 regulators (Chen Y et al. 2016).

The dipeptidyl peptidases DPP4 and DPP9 have been linked to a variety of diseases, including:

• Type 2 diabetes
• obesity and
• Tumor disease.

The DDP9 gene has also been associated with severe covid-19- infections Pairo-Castineira E et al (2020).

1. Chen Y et al. (2016) Dipeptidyl peptidase 9 enzymatic activity influences the expression of neonatal metabolic genes. Exp Cell Res 342:72-82.
2. Pairo-Castineira E et al (2020) Genetic mechanisms of critical illness in Covid-19. Nature doi: 10.1038/s41586-020-03065-y. Epub ahead of print.
3. Olsen C et al (2003). Identification and characterization of human DPP9, a novel homologue of dipeptidyl peptidase IV. Gene 299: 185-193.
4. Zapletal E et al. (2017) Expression, subcellular localization, and possible roles of dipeptidyl peptidase 9 (DPP9) in murine macrophages. Cell Biochem Funct 35:124-137.