The PIM-2 Kinase Phosphorylates BAD on Serine 112 and Reverses BAD-induced Cell Death

Abstract

Hematopoietic growth factors mediate the survival and proliferation of blood-forming cells, but the mechanisms through which these proteins produce their effects are incompletely known. Recent studies have identified the pim family of kinases as mediators of cytokinedependent survival signals. Several studies have identified substrates for the pim-1 kinase, but little is known about the other family members, pim-2 and pim-3. We have investigated potential functions for the pim-2 kinase in factor-dependent murine hematopoietic cells. We find that pim-2 mRNA and protein expression are regulated by cytokines similarly to pim-1. Three PIM-2 protein isoforms are produced in cytokinetreated cells. All three forms are active kinases, and the short (PIM-2(34 kDa)) form is the most active at enhancing survival of FDCP1 cells after cytokine withdrawal. This pro-survival function involves inhibition of apoptosis and caspase activation. Enforced expression of PIM-2(34 kDa) kinase does not appear to regulate expression of BCL-2, BCL-xL, BIM, or BAX proteins. However, the kinase can phosphorylate the pro-apoptotic protein BAD on serine 112, which accounts in part for its ability to reverse Bad-induced cell death. Our results indicate that pim-2 functions similarly to pim-1 as a pro-survival kinase and suggest that BAD is a legitimate PIM-2 substrate.

Pim-1 preserves mitochondrial morphology by inhibiting dynamin-related protein 1 translocation

“…In the past, Pim-1 has been shown to have multiple protective effects at the mitochondria (15,26,27), but a relationship between Pim-1 and mitochondrial morphologic dynamics has not been examined previously. Pim-1 overexpression prevented Drp1 accumulation at mitochondria and decreased total Drp1 levels ( Fig.…”

Regulation of mammalian horizontal gene transfer by apoptotic DNA fragmentation

“…Cells were collected, washed in PBS, and lysed in 1% Triton lysis buffer (Yan et al, 2003). Samples were denatured at 1001C for 5 min.…”

Pim2 complements Flt3 wild-type receptor in hematopoietic progenitor cell transformation

“…Previously, we and others have shown that Flt3-dependent survival signals are primarily mediated by activation of the PI3K-AKT pathway. 8,31 Indeed, both Pim2 and Akt are known to phosphorylate the antiapoptotic protein BAD, 15,16 suggesting that both pathways impinge on apoptosis regulation through modification of the Bcl2 family of proteins. Overexpression of Pim2 did not enhance the activity of AKT in our experiments (data not shown), as has been described previously.…”

“…6,11,12 Pim1 and Pim2 are shown to protect hematopoietic cells from cell death, and deficiency of Pim kinases leads to reduced body size in knockout mouse studies. 10,[13][14][15][16][17] Interestingly, when primary bone marrow-derived blast cells from patients with AML were assessed for Pim2 expression using quantitative RT-PCR, many AML patients showed overexpression of Pim2 regardless of the presence of Flt3-ITD mutations. 2 This suggests that Pim2 expression may be increased by mechanisms other than Flt3-ITD and points to a role for Pim2 in the pathogenesis of AML.…”