Pharmacoperone Identification for Therapeutic Rescue of Misfolded Mutant Proteins

G protein-coupled receptors (GPCRs), which includes the gonadotropin-releasing hormone (GnRH) receptor (GnRHR), comprises the largest family of validated drug targets – more than half of all approved drugs derive their benefits by selective targeting of GPCRs. Most drugs in this class are either agonists or antagonists of GPCRs and high throughput screens have typically been designed and performed with a view toward identification of such compounds as lead drug candidates. This manuscript presents the case that valuable drugs which effect the trafficking of GPCRs may have been overlooked because pharmacoperones have been selected from existing screens that identify agonists and antagonists. A “gain of activity assay” is proposed; this assay relies on the expression of a mutant of the GnRHR that is known to be rescuable by pharmacoperone drugs, and which is restored to activity in their presence. Accordingly, “hits” are identified by the appearance of activity. The gene for the mutant is under control of tetracycline and may be prevented from being expressed. This is a valuable feature since it allows false positives to be identified. Such drugs will show apparent activity whether or not the mutant is expressed. This assay will enable identification of these drugs from chemical libraries and does not rely on their activity as agonists or antagonists

A mathematical model for LH release in response to continuous and pulsatile exposure of gonadotrophs to GnRH

In a previous study, a model was developed to investigate the release of luteinizing hormone (LH) from pituitary cells in response to a short pulse of gonadotropin-releasing hormone (GnRH). The model included: binding of GnRH to its receptor (R), dimerization and internalization of the hormone receptor complex, interaction with a G protein, production of inositol 1,4,5-trisphosphate (IP(3)), release of calcium from the endoplasmic reticulum (ER), entrance of calcium into the cytosol via voltage gated membrane channels, pumping of calcium out of the cytosol via membrane and ER pumps, and release of LH. The extended model, presented in this paper, also includes the following physiologically important phenomena: desensitization of calcium channels; internalization of the dimerized receptors and recycling of some of the internalized receptors; an increase in G(q )concentration near the plasma membrane in response to receptor dimerization; and basal rates of synthesis and degradation of the receptors. With suitable choices of the parameters, good agreement with a variety of experimental data of the LH release pattern in response to pulses of various durations, repetition rates, and concentrations of GnRH were obtained. The mathematical model allows us to assess the effects of internalization and desensitization on the shapes and time courses of LH response curves

In the Classroom: Strategies for Poor Readers (Mar. \u2790)

All readers need successful learning experiences. Recent research suggests that poor readers benefit from using the same whole language reading and writing strategies as more successful readers. In her introduction to the April 1988 themed issue of Vie Reading Teacher on what works with poor readers. Irene West Gaskins stated: The research I was doing supported the current view that reading is a process in which an active and strategic reader gains meaning through an interaction between background knowledge and information in a text. Since I have adopted this definition, the way I teach has changed and students in the classrooms in which I teach seem to be benefitting — especially the hard-to-teach students. I no longer believe that I am successful as a teacher when most of my students are learning- Unless I have reached the hard-to-teach. I may not have taught at all. The challenge is for classroom teachers to accept responsibility for providing successful learning experiences for all children in their classrooms, including the poor readers (p. 749)

In the Classroom: Vocabulary (April \u2790)

Vocabulary knowledge is one of the most critical elements of comprehension. Helping students to expand their own vocabularies and to become more interested in words is a challenge for all teachers. The following techniques provide teachers various ways to enhance students\u27 vocabulary development. To read more about vocabulary instruction, see: Heimlich, J.E., & Pittelman, S.D. (1986). Semantic mapping: Classroom applications. Newark, DE: International Reading Association. Johnson, D.D. (Ed.) (1986). Vocabulary [Special issuel. Journal of Reading, 29 (7). Johnson, D.D., & Pearson, PD. (1984). Teaching reading vocabulary (2nd ed.). New York: Holt, Rinehart and Winston. Marzano, R.J., & Marzano, J.S. (1988). A cluster approach to elementary vocabulary instruction. Nevrark, DE: International Reading Association

In the Classroom: Reading and Writing in the Content Areas (Dec. \u2789)

Students comprehend content material by reading, discussing, writing, questioning, investigating, exploring, and organizing. Reading and writing in the content areas relates prior knowledge, classroom interaction, cooperative learning, vocabulary instruction, and questioning techniques. Children practice research skills by organizing information in a meaningful and practical manner. This month\u27s In the Classroom column presents ways in which teachers can enhance their students\u27 comprehension of content area topics by involving them in various classroom activities. Additional resources for content area reading and writing activities follow : Dupuis, M.M. (1983). Reading in the content areas: Research for teachers. Newark, DE: International Reading Association. Graves, D.H. (1989). Investigate nonfiction. Portsmouth, NH: Heinemann. Heimlich, J.E. and Pittelman, S.D. (1986). Semnntic mapping: Classroom applications. Newark, DE: International Reading Association. Marzano, R.J, and Marzano, J.S. (1988). A cluster approach to elementary vocabulary instruction. Newark, DE: International Reading Association. Thelen, J.N. (1984). Improving reading in science. Newark, DE: International Reading Association

In the Classroom: Using Children\u27s Literature (Oct. \u2789)

Lists children\u27s literature in reading instruction. Children\u27s Literature in the Reading Program ; Literature-based Reading Programs at Work ; Children\u27s Choices: Teaching With Books Children Like ; Transitions: From Literature to Literacy

Gonadotropin and Gonadal Steroid Release in Response to a Gonadotropin-Releasing Hormone Agonist in G_q^ɑ and G_(11)^ɑ Knockout Mice

In this study, we used mice lacking the G_(11)^α[ G_(11) knockout (KO)] or G_q^α gene (G_q KO) to examine LH release in response to a metabolically stable GnRH agonist (Buserelin). Mice homozygous for the absence of G_(11)^α and G_q^α appear to breed normally. Treatment of (5 wk old) female KO mice with the GnRH agonist Buserelin (2 μg/100 μl, sc) resulted in a rapid increase of serum LH levels (reaching 328 ± 58 pg/25 μl for G_(11) KO; 739 ± 95 pg/25 μl for G_q KO) at 75 min. Similar treatment of the control strain, 129SvEvTacfBr for G_(11) KO or the heterozygous mice for G_q KO, resulted in an increase in serum LH levels (428 ± 57 pg/25 μl for G_(11) KO; 884 ± 31 pg/25 μl for G_q KO) at 75 min. Both G_(11) KO and G_q KO male mice released LH in response to Buserelin (2 μg/100 μl of vehicle; 363 ± 53 pg/25μ l and 749 ± 50 pg/25 μl 1 h after treatment, respectively). These values were not significantly different from the control strain. In a long-term experiment, Buserelin was administered every 12 h, and LH release was assayed 1 h later. In female G11 KO mice and control strain, serum LH levels reached approximately 500 pg/25 μl within the first hour, then subsided to a steady level (∼100 pg/25 μl) for 109 h. In male G_(11) KO mice and in control strain, elevated LH release lasted for 13 h; however, LH levels in the G_(11) KO male mice did not reach control levels for approximately 49 h. In a similar experimental protocol, the G_q KO male mice released less LH (531 ± 95 pg/25 μl) after 13 h from the start of treatment than the heterozygous male mice (865 ± 57 pg/25 μl), but the female KO mice released more LH (634 ± 56 pg/25 μl) after 1 h from the start of treatment than the heterozygous female mice (346 ± 63 pg/25 μl). However, after the initial LH flare, the LH levels in the heterozygous mice never reached the basal levels achieved by the KO mice. G_(11) KO mice were less sensitive to low doses (5 ng/per animal) of Buserelin than the respective control mice. Male G_(11) KO mice produced more testosterone than the control mice after 1 h of stimulation by 2 μg of Buserelin, whereas there was no significant difference in Buserelin stimulated testosterone levels between G_q KO and heterozygous control mice. There was no significant difference in Buserelin stimulated estradiol production in the female G_q KO mice compared with control groups of mice. However, female G_(11) KO mice produced less estradiol in response to Buserelin (2 μg) compared with control strain. Although there were differences in the dynamics of LH release and steroid production in response to Buserelin treatment compared with control groups of mice, the lack of complete abolition of these processes, such as stimulated LH release, and steroid production, suggests that these G proteins are either not absolutely required or are able to functionally compensate for each other

An Introduction to the SMARTRISK Heroes Program: Positive Social Marketing for Adolescent Injury Prevention

This article provides background on the SMARTRISK Heroes Program, a mobile stage production that introduces young people to the prevalence of unintentional injury for their age group and presents them with a series of strategies that will reduce the likelihood that they will be unintentionally injured or killed. The program logic is consistent with theoretical work from the area of health promotion including the Protection Motivation Theory and the Transtheoretical Model of Stages of Change. The SMARTRISK Heroes Program has been the subject of a number of past evaluations that are briefly described. The program logic model was included in this article. Additional information on the program and its evaluations can be found at http://www.smartrisk.ca by selecting SMARTRISK Heroes, under the “Youth Tab.

Receptor antagonism/agonism can be uncoupled from pharmacoperone activity

Pharmacoperones rescue misrouted mutants of the vasopressin receptor type 2 (V2R) and enable them to traffic to the correct biological locus where they function. Previously, a library of nearly 645,000 structures was interrogated with a high throughput screen; pharmacoperones were identified for V2R mutants with a view toward correcting the underlying mutational defects in nephrogenic diabetes insipidus. In the present study, an orthologous assay was used to evaluate hits from the earlier study. We found no consistent relation between antagonism or agonism and pharmacoperone activity. Active pharmacoperones were identified which had minimal antagonistic activity. This increases the therapeutic reach of these drugs, since virtually all pharmacoperone drugs reported to date were selected from peptidomimetic antagonists. Such mixed-activity drugs have a complex pharmacology limiting their therapeutic utility and requiring their removal prior to stimulation of the receptor with agonist