MutSα mismatch repair protein stability is governed by subunit interaction, acetylation, and ubiquitination

In eukaryotes, DNA mismatch recognition is accomplished by the highly conserved MutSα (Msh2/Msh6) and MutSβ (Msh2/Msh3) complexes. Previously, in the yeast Saccharomyces cerevisiae, we determined that deleting MSH6 caused wild-type Msh2 levels to drop by ∼50%. In this work, we determined that Msh6 steady-state levels are coupled to increasing or decreasing levels of Msh2. Although Msh6 and Msh2 are reciprocally regulated, Msh3 and Msh2 are not. Msh2 missense variants that are able to interact with Msh6 were destabilized when Msh6 was deleted; in contrast, variants that fail to dimerize were not further destabilized in cells lacking Msh6. In the absence of Msh6, Msh2 is turned over at a faster rate and degradation is mediated by the ubiquitin-proteasome pathway. Mutagenesis of certain conserved lysines near the dimer interface restored the levels of Msh2 in the absence of Msh6, further supporting a dimer stabilization mechanism. We identified two alternative forms of regulation both with the potential to act via lysine residues, including acetylation by Gcn5 and ubiquitination by the Not4 ligase. In the absence of Gcn5, Msh2 levels were significantly decreased; in contrast, deleting Not4 stabilized Msh2 and Msh2 missense variants with partial function. The stabilizing effect on Msh2 by either the presence of Msh6 or the absence of Not4 are dependent on Gcn5. Taken together, the results suggest that the wild-type MutSα mismatch repair protein stability is governed by subunit interaction, acetylation, and ubiquitination.

Delusional versus nondelusional body dysmorphic disorder: clinical features and course of illness

DSM-IV's classification of body dysmorphic disorder (BDD) is controversial. Whereas BDD is classified as a somatoform disorder, its delusional variant is classified as a psychotic disorder. However, the relationship between these BDD variants has received little investigation. In this study, we compared BDD's delusional and nondelusional variants in 191 subjects using reliable and valid measures that assessed a variety of domains. Subjects with delusional BDD were similar to those with nondelusional BDD in terms of most variables, including most demographic features, BDD characteristics, most measures of functional impairment and quality of life, comorbidity, and family history. Delusional and nondelusional subjects also had a similar probability of remitting from BDD over 1 year of prospective follow-up. However, delusional subjects had significantly lower educational attainment, were more likely to have attempted suicide, had poorer social functioning on several measures, were more likely to have drug abuse or dependence, were less likely to currently be receiving mental health treatment, and had more severe BDD symptoms. However, when controlling for BDD symptom severity, the two groups differed only in terms of educational attainment. These findings indicate that BDD's delusional and nondelusional forms have many more similarities than differences, although on several measures delusional subjects evidenced greater morbidity, which appeared accounted for by their more severe BDD symptoms. Thus, these findings offer some support for the hypothesis that these two BDD variants may constitute the same disorder. Additional studies are needed to examine this issue, which may have relevance for other disorders with both delusional and nondelusional variants in DSM.

The conservative treatment of the anterior cruciate deficient knee

Seventy-nine recreational athletes (average age, 26 years) with complete ACL tears were treated with nonligamentous arthroscopic surgery, monitored rehabilitation, functional bracing, and activity modification. The average followup was 52 months (range, 36 to 102 months). Six (8%) patients ultimately underwent ligament reconstruction and were considered failures of nonreconstructive treatment. The remaining 73 patients were the subject of detailed analysis. There were 9 (11%) excellent, 25 (32%) good, 17 (22%) fair, and 28 (35%) poor results. Although 71 patients (97%) were satisfied with their knee for activities of daily living, only 36 (49%) were satisfied with their knee for sports. Twenty-nine (40%) had significantly modified their athletic activities. Age, sex, interval from injury to treatment, associated meniscal tears (49 or 67%), and articular cartilage damage (21 or 29%) had no apparent effect on the outcome. Poor results were noted in 29 (40%) patients with significant pivot shifts. Multiple repeat injuries, repeat arthroscopy, isokinetic deficits, and increased length of followup were also associated with poor results.