The parathyroid hormone receptorsome and the potential for therapeutic intervention.

The parathyroid hormone 1 receptor (PTH1R) is activated by parathyroid hormone (PTH) and parathyroid hormone related protein (PTHrP), hormones that mediate mineral ion homeostasis and tissue development, respectively. These diverse actions mediated by one receptor are likely due to the formation of cell-specific receptorsome complexes with cytosolic constituents. Through the second and third intracellular loops, the PTH1R couples to several G protein subclasses, including Gs, Gq/11, Gi/o and G12/13, resulting in the activation of many pathways. The PTH1R carboxy-terminal tail directs interactions with a plethora of binding partners. The WD1 and WD7 repeats of the G protein ß subunit directly bind to a novel interaction domain located near the amino-terminal end of the PTH1R carboxy-terminal tail. This Gßγ binding site likely contributes to the promiscuous G protein coupling displayed by the PTH1R. Partially overlapping this site is an EF-hand binding domain that directs interactions with calpain, a calcium-activated protease, and calmodulin, a ubiquitous calcium sensor. A lysine-arginine-lysine motif located on the juxtamembrane region of the carboxy-terminal tail mediates interactions with ezrin, an actin-membrane cross-linking protein. The C-terminus of the PTH1R binds to the sodium-hydrogen regulatory factors (NHERFs) via a PDZ domain-mediated interaction, an association that influences signaling and membrane anchoring. Through direct interactions with ezrin and NHERF-1, a PTH1R receptorsome complex exists on apical membranes of the proximal tubule, an assembly that directs PTH-mediated regulation of phosphate transport. Targeting the PTH1R receptorsome will likely enhance therapies directed towards the treatment of osteoporosis and enhancing the hematopoietic stem cell niche.

Neutrophil chemorepulsion in defined interleukin-8 gradients in vitro and in vivo.

We report for the first time that primary human neutrophils can undergo persistent, directionally biased movement away from a chemokine in vitro and in vivo, termed chemorepulsion or fugetaxis. Robust neutrophil chemorepulsion in microfluidic gradients of interleukin-8 (IL-8; CXC chemokine ligand 8) was dependent on the absolute concentration of chemokine, CXC chemokine receptor 2 (CXCR2), and was associated with polarization of cytoskeletal elements and signaling molecules involved in chemotaxis and leading edge formation. Like chemoattraction, chemorepulsion was pertussis toxin-sensitive and dependent on phosphoinositide-3 kinase, RhoGTPases, and associated proteins. Perturbation of neutrophil intracytoplasmic cyclic adenosine monophosphate concentrations and the activity of protein kinase C isoforms modulated directional bias and persistence of motility and could convert a chemorepellent to a chemoattractant response. Neutrophil chemorepulsion to an IL-8 ortholog was also demonstrated and quantified in a rat model of inflammation. The finding that neutrophils undergo chemorepulsion in response to continuous chemokine gradients expands the paradigm by which neutrophil migration is understood and may reveal a novel approach to our understanding of the homeostatic regulation of inflammation.

Perceived control in relation to socioeconomic and behavioral resources for health.

Perceived control is a personality characteristic that contributes to well-being, but few studies have attempted to integrate the functions of perceived control with those of other determinants of health. This research tested two hypotheses about the functions of perceived control: (a) individual differences in perceived control would account for socioeconomic differences in self-rated health status; (b) performance of health-related behaviors would account for the health benefits of perceived control. Using data from adult, nonproxy respondents in the National Population Health Survey of Canada (1995; n = 11, 110), confirmatory factor analysis supported a measurement model of self-rated health status composed of two correlated factors: physical health (i.e., chronic conditions. restricted activities, self-rated general health, physical functional capacity) and mental health (i.e., distress, depression). Structural equation modeling supported the first hypothesis, but not the second, regarding perceived control as a determinant of self-rated physical and mental health. Health-related behaviors partially mediated age differences in self-rated health, but different behaviors functioned in this way for men than for women. The findings suggest that psychological process, that of perceiving control over life events, underlies social inequality in health. Health-related behaviors appear not to serve as the primary mechanism through which perceived control influences health.

"I can speak for myself": involving individuals with intellectual disabilities as research participants.

The Lifespan and Disability Project, a 2-year qualitative study, was designed to enhance understanding of social integration by including the perspectives of individuals with intellectual disabilities. Procedures and strategies employed to involve these individuals in the project were documented. Specifically, we describe the use of individual interviews and focus groups (e.g., purpose, rationale, facilitation techniques) to collect data, and verification meetings in which a prompting hierarchy and cueing were employed to assist participants in confirming or disconfirming the researchers' interpretations of the emerging findings. Highlights of the results were presented to illustrate the efficacy of the strategies in enabling the participants with intellectual disabilities to share their perspectives on social integration.

Later-life planning for older adults with mental retardation: a field experiment.

A quasi-experimental design was used to assess the efficacy of a leisure education-based later-life planning model for 10 older adults with mental retardation. Prior to the initiation of the planning process, they were interviewed and completed three standardized scales designed to assess life and leisure satisfaction and leisure constraints. A comparison group completed these scales but did not participate in the planning process. At the completion of the study, both groups completed the same scales. Results demonstrated that the planning-process group had significantly higher life and leisure satisfaction at the end of the study. Many participants also made changes to their lifestyles consistent with plans made during the study. Results suggest that a later-life planning process may contribute to the quality of life of older adults with mental retardation.

Two receptor interacting domains in the nuclear hormone receptor corepressor RIP13/N-CoR.

The thyroid hormone receptor (TR) and the retinoic acid receptor (RAR) act as transcriptional repressors when they are not occupied by their cognate ligands. This repressor function is mediated by proteins called corepressors. One of the nuclear hormone receptor corepressors, N-CoR, was originally isolated as a retinoid X receptor-interacting protein called RIP13. We have isolated a new potential variant of RIP13/N-CoR that is missing previously described transcriptional repressor domains but is similar in structure to the related corepressor termed SMRT or TRAC-2. Detailed analysis of the interaction with TR and RAR demonstrates that RIP13/N-CoR contains a new receptor interaction domain, termed ID-II, in addition to the previously described domain, referred to here as ID-I. Both ID-I and ID-II are capable of interacting independently with either TR or RAR, as assessed by the yeast two-hybrid system, by a mammalian two-hybrid system, or by direct in vitro binding. Results with all three approaches confirm that RIP13/N-CoR also interacts with retinoid X receptor, but this interaction is weaker than that with TR or RAR. Together, these results demonstrate that RIP13/N-CoR can interact with several different nuclear hormone receptors via two separate receptor interaction domains. Differences between the interactions observed in the different systems suggest that corepressor function may be modified by additional factors present in various cell types.

Ah receptor phosphorylation: localization of phosphorylation sites to the C-terminal half of the protein.

The aryl hydrocarbon receptor (AhR) is a transcriptional enhancer activated by the binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related xenobiotics. Ligand binding initiates a series of poorly understood molecular events which confers recognition of cis-acting elements located in regulatory regions of particular structural genes, such as CYP1A1. Several studies have suggested that AhR phosphorylation may be instrumental in activating the AhR to a DNA-binding state. In agreement with previous investigations, treatment of the AhR with acid phosphatase resulted in the loss of DNA-binding activity. To further evaluate the functional role of AhR phosphorylation we determined whether TCDD binding altered total AhR phosphorylation, and identified phosphorylated regions by the examination of chemical cleavage patterns. The AhR was isolated by immunoprecipitation from [32P]-orthophosphate-labeled Hepa 1 cells grown in the presence or absence of TCDD. Examination of the amount of 32P associated with the AhR indicated that the total level of AhR phosphorylation was not affected by ligand binding. Chemical cleavage with hydroxylamine and cyanogen bromide also revealed a similar pattern for liganded and unliganded AhR. The shortest regions of overlap determined by the chemical cleavage patterns localized phosphorylation sites to two regions in the C-terminal half of the AhR. One region is centrally located between amino acids 368 and 605 and within or adjacent to a DNA binding repressor domain. The other region is located at the glutamine-rich carboxyl terminus between amino acids 636 and 759. These data coupled with previous observations imply that total AhR phosphorylation is not altered by the ligand-elicited transformation to a DNA-binding form, but that phosphorylation nevertheless plays an important role in the ability of an active AhR-Arnt complex to associate with cis-acting regulatory elements.

Telangiectasia macularis eruptiva perstans.

Telangiectasia macularis eruptiva perstans (TMEP) is a rare form of mastocytosis. It appears most frequently in adults and only occasionally will affect young children or infants. In this disease, multiple brownish-red confluent macules and telangiectasias develop, primarily on the trunk. Pruritus frequently occurs, and may be mild to severe. Most patients have only skin involvement; however, involvement may be systemic as well. Clinical signs and symptoms of systemic mastocytosis are varied and depend on which internal organs are affected. Classic symptoms--such as episodic flushing, gastrointestinal complaints, heart palpitations, and syncope--may be confused with those of other diseases, most notably the carcinoid syndrome. A simple workup can help to differentiate between these two conditions. The authors describe a 48-year old woman who was seen with cutaneous features of TMEP and with multiple symptoms suggesting systemic mastocytosis. They discuss the clinical features, diagnostic workup, and therapeutic options in the management of this relatively rare condition.

Apert's syndrome (acrocephalosyndactyly) in a patient with hyperhidrosis.

Apert's syndrome, also known as acrocephalosyndactyly, is a rare type of premature craniofacial synostosis characterized by the clinical triad of cranial and facial malformations along with syndactyly of the hands and feet. Acne vulgaris involving atypical sites such as the upper extremities constitutes the dermatologic hallmark of this rare genodermatosis. We report a patient who demonstrates the classic findings of Apert's syndrome. Our patient also presented with severe hyperhidrosis, which may represent a new clinical finding not previously reported in association with this syndrome.

Chelatable metal ions are not required for aryl hydrocarbon receptor transformation to a DNA binding form: phenanthrolines are possible competitive antagonists of 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The aryl hydrocarbon receptor (AhR) mediates the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds by binding DNA and altering gene transcription. We determined whether AhR transformation to a DNA binding form requires chelatable metal ions. The chelator 1,10-phenanthroline and its nonchelating isomers 1,7- and 4,7-phenanthroline blocked, in a concentration-dependent manner, TCDD-elicited transformation of the AhR in rat hepatic cytosol to a form which bound a dioxin-response element (DRE; upstream of the structural gene for cytochrome P4501A1). This was found to be due to the ability of these compounds to competitively inhibit [3H]TCDD specific binding to the AhR under conditions in vitro. EDTA (20 mM) failed to inhibit DRE binding of the transformed AhR, but pretreatment of cytosol with EDTA prior to transformation inhibited DRE binding up to 60%. However, removal of EDTA from the cytosol by gel filtration prior to incubation with TCDD resulted in the same DRE binding as filtered control cytosol without the added divalent metal ions. Both chelators, oxalic acid and iminodiacetic acid, failed to inhibit DRE binding when added prior to AhR transformation. Together these data indicate that chelatable metal ions are not required for AhR transformation to the DNA binding form.