title: Impact of subdomain D1 of the short form S1b of the human prolactin receptor on its inhibitory action on the function of the long form of the receptor induced by prolactin.
abstract: BACKGROUND
  Long-form (LF) homodimers of the human prolactin receptor (PRLR) mediate prolactin's diverse actions. Short form S1b inhibits the LF function through heterodimerization. Reduced S1b/LF-ratio in breast cancer could contribute to tumor development/progression. Current work defines the structural and functional relevance of the D1 domain of S1b on its inhibitory function on prolactin-induced LF function.
  
  
  METHODS
  Studies were conducted using mutagenesis, promoter/signaling analyses, bioluminescence resonance energy transfer (BRET) and molecular modeling approaches.
  
  
  RESULTS
  Mutation of E69 in D1 S1b or adjacent residues at the receptor surface near to the binding pocket (S) causes loss of its inhibitory effect while mutations away from this region (A) or in the D2 domain display inhibitory action as the wild-type. All S1b mutants preserved prolactin-induced Jak2 activation. BRET reveals an increased affinity in D1 mutated S1b (S) homodimers in transfected cells stably expressing LF. In contrast, affinity in S1b homodimers with either D1 (A) or D2 mutations remained unchanged. This favors LF mediated signaling induced by prolactin. Molecular dynamics simulations show that mutations (S) elicit major conformational changes that propagate downward to the D1/D2 interface and change their relative orientation in the dimers.
  
  
  CONCLUSIONS
  These findings demonstrate the essential role of D1 on the S1b structure and its inhibitory action on prolactin-induced LF-mediated function.
  
  
  CONCLUSIONS
  Major changes in receptor conformation and dimerization affinity are triggered by single mutations in critical regions of D1. Our structure-function/simulation studies provide a basis for modeling and design of small molecules to enhance inhibition of LF activation for potential use in breast cancer treatment.
authors.affiliation: Section on Molecular Endocrinology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA.
authors.forename: J-H
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Center for Molecular Modeling, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892-4510, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Hassan
authors.affiliation: Section on Molecular Endocrinology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Section on Molecular Endocrinology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Tsai-Morris
authors.affiliation: Section on Molecular Endocrinology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA. Electronic address: dufaum@mail.nih.gov.
authors.forename: M L
authors.initials: ML
authors.lastname: Dufau
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D002460:Cell Line; D019281:Dimerization; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D053614:Janus Kinase 2 / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D011388:Prolactin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D011981:Receptors, Prolactin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013329:Structure-Activity Relationship
chemical_list: D020033:Protein Isoforms; D011981:Receptors, Prolactin; D011388:Prolactin; C507924:JAK2 protein, human; D053614:Janus Kinase 2
keywords: Human prolactin receptor; Short and long form; Structure/function; Subdomain D1
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