Control of the DNA damage checkpoint by chk1 and rad53 protein kinases through distinct mechanisms

In response to DNA damage, cells activate checkpoint pathways that prevent cell cycle progression. In fission yeast and mammals, mitotic arrest in response to DNA damage requires inhibitory Cdk phosphorylation regulated by Chk1. This study indicates that Chk1 is required for function of the DNA damage checkpoint in Saccharomyces cerevisiae but acts through a distinct mechanism maintaining the abundance of Pds1, an anaphase inhibitor. Unlike other checkpoint mutants, chk1 mutants were only mildly sensitive to DNA damage, indicating that checkpoint functions besides cell cycle arrest influence damage sensitivity. Another kinase, Rad53, was required to both maintain active cyclin-dependent kinase 1, Cdk1(Cdc28), and prevent anaphase entry after checkpoint activation. Evidence suggests that Rad53 exerts its role in checkpoint control through regulation of the Polo kinase Cdc5. These results support a model in which Chk1 and Rad53 function in parallel through Pds1 and Cdc5, respectively, to prevent anaphase entry and mitotic exit after DNA damage. This model provides a possible explanation for the role of Cdc5 in DNA damage checkpoint adaptation.

[Influence of psychotherapy motivation on the course of psychotherapy]

The motivational characteristics of psychotherapy inpatients should be of crucial importance for treatment effectiveness. In the present study on 219 patients from two psychosomatic-psychotherapeutic treatment centers, four dimensions of motivation for psychotherapy (illness experience; lay etiology; treatment expectations; openness to psychotherapy) were assessed using the Questionnaire for the Measurement of Psychotherapy Motivation (Fragebogen zur Messung der Psychotherapiemotivation; FMP) and related to pre-post changes in symptomatology. In these analyses, psychological symptoms (SCL-90-R) as well as interpersonal problems (IIP) were considered as indicators of treatment effects. The results support the expectation that (a) a psychosocial causal attribution of illness symptoms and (b) a marked general openness to psychotherapy at the pretreatment interview predict more positive treatment outcomes. Implications of the results for the indication of pretreatment interventions are discussed.