Actin-capping protein regulates actomyosin contractility to maintain germline architecture in C. elegans.

Actin dynamics play an important role in tissue morphogenesis, yet the control of actin filament growth takes place at the molecular level. A challenge in the field is to link the molecular function of actin regulators with their physiological function. Here, we report an in vivo role of the actin-capping protein CAP-1 in the Caenorhabditis elegans germline. We show that CAP-1 is associated with actomyosin structures in the cortex and rachis, and its depletion or overexpression led to severe structural defects in the syncytial germline and oocytes. A 60% reduction in the level of CAP-1 caused a twofold increase in F-actin and non-muscle myosin II activity, and laser incision experiments revealed an increase in rachis contractility. Cytosim simulations pointed to increased myosin as the main driver of increased contractility following loss of actin-capping protein. Double depletion of CAP-1 and myosin or Rho kinase demonstrated that the rachis architecture defects associated with CAP-1 depletion require contractility of the rachis actomyosin corset. Thus, we uncovered a physiological role for actin-capping protein in regulating actomyosin contractility to maintain reproductive tissue architecture.

Antiemetic prophylaxis with temozolomide: an audit from a tertiary care center.

BACKGROUND: In our previous experience, a significant proportion of patients who received 5-HT3 antagonist monotherapy with adjuvant temozolomide (150-200 mg/m2) had chemotherapy-induced nausea and vomiting (CINV). This is an audit comparing the multiple antiemetic therapies in the prevention of temozolomide-associated CINV. METHODS: This was a retrospective audit. Adult glioma patients treated with temozolomide at a dose of 150-200 mg/m2 between October 2017 and June 2018 were selected for this analysis. Three antiemetic prophylaxis were used in this time period: ondansetron (October 2017 to November 2017), ondansetron + domperidone (December 2017 to February 2018), and ondansetron + olanzapine (March 2018 to June 2018). The rates of nausea and vomiting were compared among the 3 cohorts using the chi-squared test with Bonferroni correction. A P value of less than .016 was considered significant. RESULTS: A total of 360 patients were selected for this analysis. There were 91 patients in the ondansetron prophylaxis group (25.3%), 113 (31.4%) in the ondansetron plus domperidone group, and 156 (43.3%) in the ondansetron plus olanzapine group. The overall incidence of nausea and vomiting was 25.0% (n = 90) and 7.2% (n = 26). Overall the rates of nausea (P = .052) and vomiting (P = .481) were similar in all 3 cohorts. However, the rates of grade 2 and above nausea (P = .012) and vomiting (P = .015) were significantly lower in the olanzapine group. CONCLUSION: The combination of ondansetron with olanzapine leads to a statistically significant decrease in the rate of moderate-to-severe emesis and nausea and needs to be explored in a prospective study.

Principles of Actomyosin Regulation In Vivo.

The actomyosin cytoskeleton is responsible for most force-driven processes in cells and tissues. How it assembles into the necessary structures at the right time and place is an important question. Here, we focus on molecular mechanisms of actomyosin regulation recently elucidated in animal models, and highlight several common principles that emerge. The architecture of the actomyosin network - an important determinant of its function - results from actin polymerization, crosslinking and turnover, localized myosin activation, and contractility-driven self-organization. Spatiotemporal regulation is achieved by tissue-specific expression and subcellular localization of Rho GTPase regulators. Subcellular anchor points of actomyosin structures control the outcome of their contraction, and molecular feedback mechanisms dictate whether they are transient, cyclic, or persistent.