PITSLRE protein kinase activity is associated with apoptosis

Abstract

Minimal ectopic expression of a 58-kDa protein kinase (PITSLRE beta 1), distantly related to members of the cdc2 gene family, induces telophase delay, abnormal chromosome segregation, and decreased growth rates in Chinese hamster ovary cells. Here we show that this decrease in cell growth rate is due to apoptosis. Apoptosis is also induced by ectopic expression of an amino-terminal deletion mutant containing the catalytic and C-terminal domains of PITSLRE beta 1 but not by other mutants lacking histone H1 kinase activity or by other members of the cdc2 gene family. However, unlike the wild-type PITSLRE beta 1 over-expressors, ectopic expression of the N-terminal PITSLRE beta 1 mutant does not result in telophase delay or abnormal chromosome segregation. These results suggested that the function of this protein kinase could be linked to apoptotic signaling. To test this hypothesis, we examined levels of PITSLRE mRNA, steady-state protein, and enzyme activity in human T cells undergoing apoptosis after activation with the anti-Fas monoclonal antibody (MAb). All were substantially elevated shortly after Fas MAb treatment. In addition to new transcription and translation, proteolysis contributed to the increased steady-state levels of a novel 50-kDa PITSLRE protein, as suggested by the diminution of larger PITSLRE isoforms observed in the same cells. Indeed, treatment of the Fas-activated T cells with a serine protease inhibitor prevented apoptotic death and led to the accumulation of larger, less active PITSLRE kinase isoforms but not the enzymatically active 50-kDa PITSLRE isoform. Finally, induction of apoptosis by glucocorticoids in the same cell line, as well as by Fas MAb treatment of another T-cell line, led to a similar induction of 50-kDa PITSLRE protein levels over time. These findings suggest that (i) PITSLRE kinase(s) may lie within apoptotic signaling pathway(s), (ii) serine protease activation may be an early event in Fas-activated apoptosis of human T cells, and (iii) some PITSLRE kinase isoforms may be targets of apoptotic proteases.

Death-associated protein kinase 2 is a new calcium/calmodulin-dependent protein kinase that signals apoptosis through its catalytic activity

“…Activation of cyclin dependent-protein kinase (CDK), Cdc2 kinase was correlated with apoptosis of lymphoma cells induced by granzyme B (Shi et al, 1994). An additional CDK, p58 PITSRLE induced apoptosis upon overexpression in Chinese hamster ovary cells and was activated by Fas-stimulation (Lahti et al, 1995). FAST and RICK (also known as RIP2) kinases are also implicated in Fas-mediated apoptosis (Tian et al, 1995;Inohara et al, 1998;McCarthy et al, 1998).…”

Quiescence versus apoptosis: Myc abundance determines pathway of exit from the cell cycle

“…As observed with Myc, elevated cyclin levels can result either in transformation (Motokura et al, 1991;Withers et al, 1991) or in apoptosis (Freeman et al, 1994;Hoang et al, 1994;Lahti et al, 1995;Meikrantz et al, 1994;Meikrantz and Schlegel, 1996;Sherr and Roberts, 1995;Shi et al, 1994), and dominant negative mutants of cdc2, cdk2 and cdk3 can suppress apoptosis (Meikrantz and Schlegel, 1996). Direct links between the activation of Myc and cdks have been proposed (Galaktionov et al, 1996;Hoang et al, 1994;Rudolph et al, 1996;Steiner et al, 1995) and build on the concept that the inappropriate overexpression of c-myc may cause aberrant cell cycle events as a prelude to apoptosis in cells predisposed to this condition.…”

Cytogenetic characterization of HB2 epithelial cells from the human breast

“…Interestingly, 1p22 band contains the dihydropyrimidine dehydrogenase gene, which encodes an initial and rate-limiting enzyme acting in the uracil and thymine catabolic pathways and being responsible for degradation of 5-fluorouracil, which is also considered as a potential prognostic marker for breast cancers (Li et al 2004). Moreover, 1p33 band contains the cyclin-dependent kinase inhibitor 2C gene encoding p18 of the INK4 family which functions as a cell cycle regulator that controls G 1 progression via inhibition of CDK4 (Guan et al 1994), whereas the cell division cycle 2-like 2 (PITSLRE protein) variant 3 gene, encoding a member of the subfamily of p34 cdc2 -related protein kinases which intervene in the regulation of apoptosis, and at least other three potential tumor suppressor genes (i.e., Heir-1, TNFR , and DAN) are located in band 1p36 which contains another aphidicolin-inducible chromosomal fragile site (Lahti et al 1995;Thompson et al 1997;Tunca et al 2000).…”