Identification of an Hexapeptide That Binds to a Surface Pocket in Cyclin A and Inhibits the Catalytic Activity of the Complex Cyclin-dependent Kinase 2-Cyclin A

Role of CDK5/cyclin complexes in ischemia-induced death and survival of renal tubular cells

“…The IC 50 value for the CDK5/cyclin I complex has not been in vitro determined due to cyclin I purification problems. Nevertheless, the mechanism of action of TAT-NBI1 is based on TAT-NBI1 binding to a cyclin groove present in cyclin A that is non-existent in cyclin E. 7 TAT-NBI1 specificity is reflected in the IC 50 s obtained for both complexes (Table S1). The molecular modeling studies of cyclin I described in the bibliography show that cyclin I is a homolog to cyclin E, 37,38 thereby supporting the differential inhibition proposed for TAT-NBI1 of both complexes.…”

“…Both roscovitine 17 and TAT-NBI1 7,8 induced cell death in tumor cell lines. Then we first determined the sensitivity of the LLC-PK1 cell line to these compounds in order to define sublethal concentrations.…”

“…TAT-NBI1 was synthesized as previously described 7 and is also available from Calbiochem (238808), while roscovitine (R7772) was obtained from Sigma-Aldrich. pCMV-HA-tagged Cdk5 (#1872) and HA-tagged dominant-negative (D145N) Cdk5 (#1873) (both) were purchased from Addgene.…”

“…7,8 The cellular model we used was the I/R model developed from an epithelial cell line deriving from pig kidney proximal tubule cells (LLC-PK1). 9 In this cell model, cells are subjected to hypoxia (1% O 2 ) and hypercapnia (18% CO 2 ) for 24 h, and Ischemia reperfusion processes induce damage in renal tubules and compromise the viability of kidney transplants.…”

“…It has been previously proposed that cyclin-dependent kinases (CDK) participate in ischemia-induced neuronal death, 4 and that CDK inhibitors provide protection. 5 Here we report that the CDK inhibitors roscovitine 6 and TAT-NBI1 7,8 provide protection against cell death in a well-established ischemia/reperfusion (I/R) model in porcine renal tubular cells (LLC-PK1). 9 When analyzing the molecular mechanism, we found the protective effect required of CDK5.…”