Anti-CKB monoclonal antibody, clone DL-CZL/32F21 Knockout Validated

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9) is a specific substrate-recognition subunit of an elongin C-cullin-SOCS box E3 ubiquitin ligase complex. It recognizes its substrate, brain type creatine kinase (CKB), using the ankyrin repeat domain; and facilitates the polyubiquitination of CKB to mediate proteasomal degradation through the SOCS box domain. HASB9-2 is an isoform of hASB9 that contains one ankyrin repeat domain. In this study, the crystal structure of hASB9-2 is shown at 2.2- resolution using molecular replacement. Overall, hASB9-2 forms a slightly curved arch with a characteristic L-shaped cross-section. Amino acid substitution analysis based on docking experiments revealed that His103 and Phe107 in hASB9-2 are essential for binding to CKB. Analysis of truncation mutants demonstrated that the first six ankyrin repeats along with the N-terminal region of hASB9-2 contribute to the interaction with CKB.

Trigonelline (TGN; 1-methylpyridin-1-ium-3-carboxylate) is a widely distributed alkaloid derived from plants. Since we previously found a neurite outgrowth effect of TGN, we hypothesised that TGN might help to improve memory deficits. Here, the efficacy of TGN in restoring amyloid beta (A beta)-induced axonal degeneration and in improving memory function was investigated in Alzheimer's disease 5XFAD model mice that overexpress mutated APP and PS1 genes. Exposure of A beta 25-35 for 3 days induced atrophy of axons and dendrites. Post treatment of TGN recovered the lengths of axons and dendrites. Following oral administration of TGN in mice, TGN itself was detected in the plasma and cerebral cortex. Oral administration of TGN to 5XFAD mice for 14 days showed significant improvement in object recognition memory (P<0.001) and object location memory (P<0.01). TGN administration also normalised neurofilament light levels in the cerebral cortex (P<0.05), which is an axonal damage-associated biomarker. Analysis of target proteins of TGN in neurons by a drug affinity responsive target stability (DARTS) method identified that creatine kinase B-type (CKB) is a direct binding protein of TGN. Treatment with a CKB inhibitor cancelled the TGN-induced axonal and dendritic growth. In conclusion, we found for the first time that TGN penetrates the brain and may activate CKB, leading to axonal formation. This study shows the potential of TGN as a new drug candidate, and a new target molecule, CKB, in memory recovery signalling.