Geometry and expression enhance enrichment of functional yeast-displayed ligands via cell panning.

Yeast surface display has proven to be an effective tool in the discovery and evolution of ligands with new or improved binding activity. Selections for binding activity are generally carried out using immobilized or fluorescently labeled soluble domains of target molecules such as recombinant ectodomain fragments. While this method typically provides ligands with high affinity and specificity for the soluble molecular target, translation to binding true membrane-bound cellular target is commonly problematic. Direct selections against mammalian cell surfaces can be carried out either exclusively or in combination with soluble target-based selections to further direct towards ligands for genuine cellular target. Using a series of fibronectin domain, affibody, and Gp2 ligands and human cell lines expressing a range of their targets, epidermal growth factor receptor and carcinoembryonic antigen, this study quantitatively identifies the elements that dictate ligand enrichment and yield. Most notably, extended flexible linkers between ligand and yeast enhance enrichment ratios from 1.4 ± 0.8 to 62 ± 57 for a low-affinity (>600 nM) binder on cells with high target expression and from 14 ± 13 to 74 ± 25 for a high-affinity binder (2 nM) on cells with medium valency. Inversion of the yeast display fusion from C-terminal display to N-terminal display still enables enrichment albeit with 40-97% reduced efficacy. Collectively, this study further enlightens the conditions-while highlighting new approaches-that yield successful enrichment of yeast-displayed binding ligands via panning on mammalian cells. Biotechnol. Bioeng. 2016;113: 2328-2341. © 2016 Wiley Periodicals, Inc.

Depressive and anxiety disorders and antidepressant prescriptions among insured children and young adults with congenital adrenal hyperplasia in the United States.

Background: Dysfunction in the hypothalamic-pituitary-adrenal axis has been associated with depressive and anxiety disorders. Little is known about the risk for these disorders among individuals with congenital adrenal hyperplasia (CAH), a form of primary adrenal insufficiency. Objective: We investigated the prevalence of depressive and anxiety disorders and antidepressant prescriptions in two large healthcare databases of insured children, adolescents, and young adults with CAH in the United States. Methods: We conducted a retrospective cohort study using administrative data from October 2015 through December 2019 for individuals aged 4-25 years enrolled in employer-sponsored or Medicaid health plans. Results: Adjusting for age, the prevalence of depressive disorders [adjusted prevalence ratio (aPR) = 1.7, 95% confidence interval (CI): 1.4-2.0, p<0.001], anxiety disorders [aPR = 1.7, 95% CI: 1.4-1.9, p<0.001], and filled antidepressant prescriptions [aPR = 1.7, 95% CI: 1.4-2.0, p<0.001] was higher among privately insured youth with CAH as compared to their non-CAH peers. Prevalence estimates were also higher among publicly insured youth with CAH for depressive disorders [aPR = 2.3, 95% CI: 1.9-2.9, p<0.001], anxiety disorders [aPR = 2.0, 95% CI: 1.6-2.5, p<0.001], and filled antidepressant prescriptions [aPR = 2.5, 95% CI: 1.9-3.1, p<0.001] as compared to their non-CAH peers. Conclusions: The elevated prevalence of depressive and anxiety disorders and antidepressant prescriptions among youth with CAH suggests that screening for symptoms of depression and anxiety among this population might be warranted.

Attention-Deficit/Hyperactivity Disorder Among US Children and Adolescents With Congenital Adrenal Hyperplasia.

BACKGROUND: Little is known regarding risk for co-occurring mental health conditions among pediatric patients with congenital adrenal hyperplasia (CAH). The objective of the current study was to investigate the prevalence of medically managed attention-deficit/hyperactivity disorder (ADHD) in 2 large administrative samples of insured children and adolescents with and without CAH in the United States. METHODS: We assessed the prevalence of CAH and of medically managed ADHD using algorithms defined from diagnosis codes and filled prescriptions data using the IBM MarketScan Commercial and Multi-State Medicaid claims databases. We evaluated subjects who were continuously enrolled for ≥ 12 months with a first claim during October 2015 through December 2017 when they were 5 to 18 years old. RESULTS: The administrative prevalence of CAH in the Commercial (N = 3 685 127) and Medicaid (N = 3 434 472) samples was 10.1 per 100 000 (n = 372) and 7.2 per 100 000 (n = 247), respectively. The prevalence of medically managed ADHD in the non-CAH population was 8.4% in the Commercial sample and 15.1% in the Medicaid sample. Among children with CAH, there was no increased prevalence of ADHD in the Commercial (9.2%, prevalence ratio [PR] = 1.1; 95% confidence interval [CI], 0.82-1.54; P = 0.48) or Medicaid (13.8%; PR = 0.91; 95% CI, 0.67-1.24; P = 0.55) samples compared with the general population. CONCLUSIONS: Using 2 large samples of insured children and adolescents in the United States, we found similar prevalence of medically managed ADHD among those with CAH and the general population. Future research to assess the validity of our claims algorithm for identifying pediatric CAH cases is warranted.

Centromere mechanical maturation during mammalian cell mitosis.

During mitosis, tension develops across the centromere as a result of spindle-based forces. Metaphase tension may be critical in preventing mitotic chromosome segregation errors, however, the nature of force transmission at the centromere and the role of centromere mechanics in controlling metaphase tension remains unknown. We combined quantitative, biophysical microscopy with computational analysis to elucidate the mechanics of the centromere in unperturbed, mitotic human cells. We discovered that the mechanical stiffness of the human centromere matures during mitotic progression, which leads to amplified centromere tension specifically at metaphase. Centromere mechanical maturation is disrupted across multiple aneuploid cell lines, leading to a weak metaphase tension signal. Further, increasing deficiencies in centromere mechanical maturation are correlated with rising frequencies of lagging, merotelic chromosomes in anaphase, leading to segregation defects at telophase. Thus, we reveal a centromere maturation process that may be critical to the fidelity of chromosome segregation during mitosis.

A Gradient in Metaphase Tension Leads to a Scaled Cellular Response in Mitosis.

During mitosis, motor proteins associate with microtubules to exert pushing forces that establish a mitotic spindle. These pushing forces generate opposing tension in the chromatin that connects oppositely attached sister chromatids, which may then act as a mechanical signal to ensure the fidelity of chromosome segregation during mitosis. However, the role of tension in mitotic cellular signaling remains controversial. In this study, we generated a gradient in tension over multiple isogenic budding yeast cell lines by genetically altering the magnitude of motor-based spindle forces. We found that a decreasing gradient in tension led to an increasing gradient in the rates of kinetochore detachment and anaphase chromosome mis-segregration, and in metaphase time. Simulations and experiments indicated that these tension responses originate from a tension-dependent kinetochore phosphorylation gradient. We conclude that the cell is exquisitely tuned to the magnitude of tension as a signal to detect potential chromosome segregation errors during mitosis.