Childhood Pityriasis Rosea

Abstract: Pityriasis rosea (PR) is an acute, self‐limiting papulosquamous disorder of unknown etiology. Published studies of childhood PR are scarce and most are reviews. The aim of this study was to determine the demographic and clinical features of childhood PR.     

Neurological and adrenal dysfunction in the adrenal insufficiency/alacrima/achalasia (3A) syndrome

Review of 20 patients with glucocorticoid deficiency (three cases also with salt loss) associated with absent tear secretion (19 cases) and achalasia of the cardia (15 cases) revealed neurological abnormalities in 17 including hyper-reflexia, muscle weakness, dysarthria, and ataxia together with impaired intelligence and abnormal autonomic function, particularly postural hypotension. These findings indicate that significant neurological problems are common in this multisystem disorder.     

Quantitative analysis of neuropeptide Y receptor association with ��-arrestin2 measured by bimolecular fluorescence complementation

Background and purpose:

β-Arrestins are critical scaffold proteins that shape spatiotemporal signalling from seven transmembrane domain receptors (7TMRs). Here, we study the association between neuropeptide Y (NPY) receptors and β-arrestin2, using bimolecular fluorescence complementation (BiFC) to directly report underlying protein–protein interactions.

Experimental approach:

Y1 receptors were tagged with a C-terminal fragment, Yc, of yellow fluorescent protein (YFP), and β-arrestin2 fused with the complementary N-terminal fragment, Yn. After Y receptor–β-arrestin association, YFP fragment refolding to regenerate fluorescence (BiFC) was examined by confocal microscopy in transfected HEK293 cells. Y receptor/β-arrestin2 BiFC responses were also quantified by automated imaging and granularity analysis.

Key results:

NPY stimulation promoted association between Y1–Yc and β-arrestin2–Yn, and the specific development of BiFC in intracellular compartments, eliminated when using non-interacting receptor and arrestin mutants. Responses developed irreversibly and were slower than for downstream Y1 receptor–YFP internalization, a consequence of delayed maturation and stability of complemented YFP. However, β-arrestin2 BiFC measurements delivered appropriate ligand pharmacology for both Y1 and Y2 receptors, and demonstrated higher affinity of Y1 compared to Y2 receptors for β-arrestin2. Receptor mutagenesis combined with β-arrestin2 BiFC revealed that alternative arrangements of Ser/Thr residues in the Y1 receptor C tail could support β-arrestin2 association, and that Y2 receptor–β-arrestin2 interaction was enhanced by the intracellular loop mutation H155P.

Conclusions and implications:

The BiFC approach quantifies Y receptor ligand pharmacology focused on the β-arrestin2 pathway, and provides insight into mechanisms of β-arrestin2 recruitment by activated and phosphorylated 7TMRs, at the level of protein–protein interaction.