Identification of a Novel Class of Farnesylation Targets by Structure-Based Modeling of Binding Specificity

Farnesylation is an important post-translational modification catalyzed by farnesyltransferase (FTase). Until recently it was believed that a C-terminal CaaX motif is required for farnesylation, but recent experiments have revealed larger substrate diversity. In this study, we propose a general structural modeling scheme to account for peptide binding specificity and recapitulate the experimentally derived selectivity profile of FTase in vitro. In addition to highly accurate recovery of known FTase targets, we also identify a range of novel potential targets in the human genome, including a new substrate class with an acidic C-terminal residue (CxxD/E). In vitro experiments verified farnesylation of 26/29 tested peptides, including both novel human targets, as well as peptides predicted to tightly bind FTase. This study extends the putative range of biological farnesylation substrates. Moreover, it suggests that the ability of a peptide to bind FTase is a main determinant for the farnesylation reaction. Finally, simple adaptation of our approach can contribute to more accurate and complete elucidation of peptide-mediated interactions and modifications in the cell

<i>In Silico</i> and <i>in Vitro</i> Elucidation of BH3 Binding Specificity toward Bcl-2

Interactions between Bcl-2-like proteins and BH3 domains play a key role in the regulation of apoptosis. Despite the overall structural similarity of their interaction with helical BH3 domains, Bcl-2-like proteins exhibit an intricate spectrum of binding specificities whose underlying basis is not well understood. Here, we characterize these interactions using Rosetta FlexPepBind, a protocol for the prediction of peptide binding specificity that evaluates the binding potential of different peptides based on structural models of the corresponding peptide–receptor complexes. For two prominent players, Bcl-xL and Mcl-1, we obtain good agreement with a large set of experimental SPOT array measurements and recapitulate the binding specificity of peptides derived by yeast display in a previous study. We extend our approach to a third member of this family, Bcl-2: we test our blind prediction of the binding of 180 BIM-derived peptides with a corresponding experimental SPOT array. Both prediction and experiment reveal a Bcl-2 binding specificity pattern that resembles that of Bcl-xL. Finally, we extend this application to accurately predict the specificity pattern of additional human BH3-only derived peptides. This study characterizes the distinct patterns of binding specificity of BH3-only derived peptides for the Bcl-2 like proteins Bcl-xL, Mcl-1, and Bcl-2 and provides insight into the structural basis of determinants of specificity

Dorsal/ventral parcellation of the amygdala: relevance to impulsivity and aggression

Investigations into the specific association of amygdala volume, a critical aspect of the fronto-limbic emotional circuitry, and aggression have produced results broadly consistent with the \u27larger is more powerful\u27 doctrine. However, recent reports suggest that the ventral and dorsal aspects of the amygdala play functionally specific roles, respectively, in the activation and control of behavior. Therefore, parceling amygdala volume into dorsal and ventral components might prove productive in testing hypotheses regarding volumetric association to aggression, and impulsivity, a related aspect of self-control. We sought to test this hypothesis in a group of 41 psychiatric patients who received standard magnetic resonance imaging and a psychometric protocol including aggression and impulsivity measures. Whole amygdala volumes were not associated with aggression or impulsivity, but significant correlations were found when dorsal/ventral amygdalae were analyzed separately. Specifically, left and right ventral amygdala volume was positively associated with motor impulsivity, and left dorsal amygdala was negatively associated with aggression. Results are discussed in terms of an activation and control model of brain-behavior relations. Potential relevance to the continuum of amygdala hyper- to hypo-activation and aggression is discussed

Electroencephalographic Correlates of Continuous Postural Tasks of Increasing Difficulty.

Cortical involvement in postural control is well recognized, however the role of non-visual afferents remains unclear. Parietal cortical areas are strongly implicated in vestibulo-spatial functions, but topographical localization during balance tasks remains limited. Here, we use electroencephalography (EEG) during continuous balance tasks of increasing difficulty at single electrode positions. Twenty-four healthy, right-handed individuals performed four balance tasks of increasing difficulty (bipedal and unipedal) and a seated control condition with eyes closed. Subjective ratings of task difficulty were obtained. EEG was recorded from 32 electrodes; 5 overlying sensory and motor regions of interest (ROIs) were chosen for further investigation: C3, Cz, C4, P3, P4. Spectral power and coherence during balance tasks were analyzed in theta (4-8 Hz) and alpha (8-12 Hz) bands. Alpha power reduced as task difficulty increased and this reduction correlated with subjective difficulty ratings. Alpha coherence increased with task difficulty between C3-Cz-C4 electrode pairs. Differential changes in power were observed in Cz, suggestive of a distinct role at this electrode location, which captures lower limb cortical representation. Hemispheric asymmetry was observed, as reflected by greater reductions in theta and alpha power in right-sided areas. Our results demonstrate the functional importance of bilateral central and parietal cortices in continuous balance control. The hemispheric asymmetry observed implies that the non-dominant hemisphere is involved with online monitoring of postural control. Although the posterior parietal asymmetry found may relate to vestibular, somatosensory or multisensory feedback processing, we argue that the finding relates to active balance control rather than simple sensory-intake or reflex circuit activation

Taking an Antibiotic Time-out: Utilization and Usability of a Self-Stewardship Time-out Program for Renewal of Vancomycin and Piperacillin-Tazobactam.

BackgroundAntibiotic time-outs can promote critical thinking and greater attention to reviewing indications for continuation.ObjectiveWe pilot tested an antibiotic time-out program at a tertiary care teaching hospital where vancomycin and piperacillin-tazobactam continuation past day 3 had previously required infectious diseases service approval.MethodsThe time-out program consisted of 3 components: (1) an electronic antimicrobial dashboard that aggregated infection-relevant clinical data; (2) a templated note in the electronic medical record that included a structured review of antibiotic indications and that provided automatic approval of continuation of therapy when indicated; and (3) an educational and social marketing campaign.ResultsIn the first 6 months of program implementation, vancomycin was discontinued by day 5 in 93/145 (64%) courses where a time-out was performed on day 4 versus in 96/199 (48%) 1 year prior (P = .04). Seven vancomycin continuations via template (5% of time-outs) were guideline-discordant by retrospective chart review versus none 1 year prior (P = .002). Piperacillin-tazobactam was discontinued by day 5 in 70/105 (67%) courses versus 58/93 (62%) 1 year prior (P = .55); 9 continuations (9% of time-outs) were guideline-discordant versus two 1 year prior (P = .06). A usability survey completed by 32 physicians demonstrated modest satisfaction with the overall program, antimicrobial dashboard, and renewal templates.ConclusionsBy providing practitioners with clinical informatics support and guidance, the intervention increased provider confidence in making decisions to de-escalate antimicrobial therapy in ambiguous circumstances wherein they previously sought authorization for continuation from an antimicrobial steward

Synergistic drug combinations with a CDK4/6 inhibitor in T-cell acute lymphoblastic leukemia

Purpose: Although significant progress has been made in the treatment of T-cell acute lymphoblastic leukemia (T-ALL), many patients will require additional therapy for relapsed/refractory disease. Cyclin D3 (CCND3) and CDK6 are highly expressed in T-ALL and have been effectively targeted in mutant NOTCH1-driven mouse models of this disease with a CDK4/6 small-molecule inhibitor. Combination therapy, however, will be needed for the successful treatment of human disease. Experimental Design: We performed preclinical drug testing using a panel of T-ALL cell lines first with LEE011, a CDK4/6 inhibitor, and next with the combination of LEE011 with a panel of drugs relevant to T-ALL treatment. We then tested the combination of LEE011 with dexamethasone or everolimus in three orthotopic mouse models and measured on-target drug activity. Results: We first determined that both NOTCH1-mutant and wild-type T-ALL are highly sensitive to pharmacologic inhibition of CDK4/6 when wild-type RB is expressed. Next, we determined that CDK4/6 inhibitors are antagonistic when used either concurrently or in sequence with many of the drugs used to treat relapsed T-ALL (methotrexate, mercaptopurine, asparaginase, and doxorubicin) but are synergistic with glucocorticoids, an mTOR inhibitor, and gamma secretase inhibitor. The combinations of LEE011 with the glucocorticoid dexamethasone or the mTOR inhibitor everolimus were tested in vivo and prolonged survival in three orthotopic mouse models of T-ALL. On-target activity was measured in peripheral blood and tissue of treated mice. Conclusions: We conclude that LEE011 is active in T-ALL and that combination therapy with corticosteroids and/or mTOR inhibitors warrants further investigation

Extended Treatment with Single-Agent Ibrutinib at the 420 mg Dose Leads to Durable Responses in Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Purpose: Ibrutinib, a first-in-class, once-daily, oral inhibitor of Bruton tyrosine kinase, promotes apoptosis, and inhibits B-cell proliferation, adhesion, and migration. Ibrutinib has demonstrated single-agent efficacy and acceptable tolerability at doses of 420 and 840 mg in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) who were treatment-naïve (TN) or had relapsed/refractory (R/R) CLL after ≥1 prior therapy in a phase Ib/II study (PCYC-1102). Subsequently, the ibrutinib 420 mg dose was approved in CLL.Experimental Design: We report data with 44 months of follow-up on 94 patients with TN and R/R CLL/SLL receiving ibrutinib 420 mg once-daily in PCYC-1102 and the long-term extension study PCYC-1103.Results: Ninety-four CLL/SLL patients (27 TN, 67 R/R) were treated with ibrutinib (420 mg/day). Patients with R/R disease had received a median of four prior therapies (range, 1-12). Responses were rapid and durable and median duration of response was not reached. Best overall response was 91% [85% TN (complete response, CR 26%) and 94% R/R (9% CR)]. Median progression-free survival (PFS) was not reached in either group. The 30-month PFS rate was 96% and 76% for TN and R/R patients, respectively. Ibrutinib was well tolerated with extended follow-up; rates of grade ≥3 cytopenias and fatigue, as well as discontinuations due to toxicities decreased over time.Conclusions: Single-agent ibrutinib at 420 mg once-daily resulted in durable responses and was well tolerated with up to 44 months follow-up in patients with TN and R/R CLL/SLL. Currently, 66% of patients continue on ibrutinib. Clin Cancer Res; 23(5); 1149-55. ©2017 AACR

Factors associated with suicide mortality among reproductive age women: a case-control study

OBJECTIVE: Examine demographic, psychosocial, pregnancy-related, and healthcare utilisation factors associated with suicide mortality among reproductive age women. METHODS: Data from nine health care systems in the Mental Health Research Network were included. A case-control study design was used in which 290 reproductive age women who died by suicide (cases) from 2000 to 2015 were matched with 2,900 reproductive age women from the same healthcare system who did not die by suicide (controls). Conditional logistic regression was used to analyse associations between patient characteristics and suicide. RESULTS: Women of reproductive age who died by suicide were more likely to have mental health (aOR = 7.08, 95% CI: 5.17, 9.71) or substance use disorders (aOR = 3.16, 95% CI: 2.19, 4.56) and to have visited the emergency department in the year prior to index date (aOR = 3.47, 95% CI: 2.50, 4.80). Non-Hispanic White women (aOR = 0.70, 95% CI: 0.51, 0.97) and perinatal (pregnant or postpartum) women were less likely to have died by suicide (aOR = 0.27, 95% CI: 0.13, 0.58). CONCLUSIONS: Reproductive age women with mental health and/or substance use disorders, prior emergency department encounters, or who are of racial or ethnic minority status were at increased risk of suicide mortality and may benefit from routine screening and monitoring. Future research should further examine the relationship between pregnancy-related factors and suicide mortality