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Growing evidence indicates a critical role of ubiquitin‐proteosome system in apoptosis regulation. A cardioprotective effect of ubiquitin (Ub) ligase of the C terminus of Hsc70‐interacting protein (CHIP) on myocytes has been reported. In the current study, we found that the cardioprotective effect of insulin growth factor‐1 (IGF‐1) was mediated by ERK5‐CHIP signal module via inducible cAMP early repressor (ICER) destabilization. In vitro runoff assay and Ub assay showed ICER as a substrate of CHIP Ub ligase. Both disruption of ERK5‐CHIP binding with inhibitory helical linker domain fragment (aa 101–200) of CHIP and the depletion of ERK5 by siRNA inhibited CHIP Ub ligase activity, which suggests an obligatory role of ERK5 on CHIP activation. Depletion of CHIP, using siRNA, inhibited IGF‐1‐mediated reduction of isoprot‐erenol‐mediated ICER induction and apoptosis. In diabetic mice subjected to myocardial infarction, the CHIP Ub ligase activity was decreased, with an increase in ICER expression. These changes were attenuated significantly in a cardiac‐specific constitutively active form of MEK5α transgenic mice (CA‐MEK5α‐Tg) previously shown to have greater functional recovery. Furthermore, pressure overload‐mediated ICER induction was enhanced in heterozygous CHIP+/_ mice. We identified ICER as a novel CHIP substrate and that the ERK5‐CHIP complex plays an obligatory role in inhibition of ICER expression, cardiomyocyte apoptosis, and cardiac dysfunction.—Woo, C.‐H., Le, N.‐T., Shishido, T., Chang, E., Lee, H., Heo, K.‐S., Mickelsen, D. M., Lu, Y., McClain, C., Spangenberg, T., Yan, C., Molina, C. A., Yang, J., Patterson, C., Abe, J.‐I. Novel role of C terminus of Hsc70‐interacting protein (CHIP) ubiquitin ligase on inhibiting cardiac apoptosis and dysfunction via regulating ERK5‐mediated degradation of inducible cAMP early repressor. FASEB J. 24, 4917–4928 (2010). www.fasebj.org [ABSTRACT FROM AUTHOR]

Clinical infusion of haematopoietic stem and progenitor cells (HSPCs) is vital for restoration of haematopoietic function in many cancer patients. Previously, we have demonstrated an ability to mimic physiological cell trafficking in order to capture CD34-positive (CD34+) HSPCs using monolayers of the cell adhesion protein P-selectin in flow chambers. The current study aimed to determine if HSPCs could be captured directly from circulating blood in vivo. Vascular shunt prototypes, coated internally with P-selectin, were inserted into the femoral artery of rats. Blood flow through the cell capture device resulted in a wall shear stress of 4–6 dynes/cm2. After 1-h blood perfusion, immunofluorescence microscopy and flow cytometric analysis revealed successful capture of mononuclear cells positive for the HSPC surface marker CD34. Purity of captured CD34+ cells showed sevenfold enrichment over levels found in whole blood, with an average purity of 28%. Robust cell capture and HSPC enrichment were also demonstrated in devices that were implanted in a closed-loop arterio-venous shunt conformation for 2 h. Adherent cells were viable in culture and able to differentiate into burst-forming units. This study demonstrated an ability to mimic the physiological arrest of HSPCs from blood in an implantable device and may represent a practical alternative for adult stem cell capture and enrichment. [ABSTRACT FROM AUTHOR]