GHR/PRLR Heteromultimer Is Composed of GHR Homodimers and PRLR Homodimers. Mol Endocrinol 2016 May;30(5):504-17
Date
03/24/2016Pubmed ID
27003442Pubmed Central ID
PMC4853563DOI
10.1210/me.2015-1319Scopus ID
2-s2.0-84964876556 (requires institutional sign-in at Scopus site) 15 CitationsAbstract
GH receptor (GHR) and prolactin (PRL) receptor (PRLR) are homologous transmembrane cytokine receptors. Each prehomodimerizes and ligand binding activates Janus Kinase 2 (JAK2)-signal transducer and activator of transcription (STAT) signaling pathways by inducing conformational changes within receptor homodimers. In humans, GHR is activated by GH, whereas PRLR is activated by both GH and PRL. We previously devised a split luciferase complementation assay, in which 1 receptor is fused to an N-terminal luciferase (Nluc) fragment, and the other receptor is fused to a C-terminal luciferase (Cluc) fragment. When receptors approximate, luciferase activity (complementation) results. Using this assay, we reported ligand-independent GHR-GHR complementation and GH-induced complementation changes characterized by acute augmentation above basal signal, consistent with induction of conformational changes that bring GHR cytoplasmic tails closer. We also demonstrated association between GHR and PRLR in T47D human breast cancer cells by coimmunoprecipitation, suggesting that, in addition to forming homodimers, these receptors form hetero-assemblages with functional consequences. We now extend these analyses to examine basal and ligand-induced complementation of coexpressed PRLR-Nluc and PRLR-Cluc chimeras and coexpressed GHR-Nluc and PRLR-Cluc chimeras. We find that PRLR-PRLR and GHR-PRLR form specifically interacting ligand-independent assemblages and that either GH or PRL augments PRLR-PRLR complementation, much like the GH-induced changes in GHR-GHR dimers. However, in contrast to the complementation patterns for GHR-GHR or PRLR-PRLR homomers, both GH and PRL caused decline in luciferase activity for GHR-PRLR heteromers. These and other data suggest that GHR and PRLR associate in complexes comprised of GHR-GHR/PRLR-PRLR heteromers consisting of GHR homodimers and PRLR homodimers, rather than GHR-PRLR heterodimers.
Author List
Liu Y, Zhang Y, Jiang J, Lobie PE, Paulmurugan R, Langenheim JF, Chen WY, Zinn KR, Frank SJMESH terms used to index this publication - Major topics in bold
Breast NeoplasmsCarrier Proteins
Cell Line, Tumor
Female
Growth Hormone
Humans
Immunoprecipitation
Janus Kinase 2
Ligands
Luciferases
Protein Binding
Protein Multimerization
Receptors, Prolactin
Signal Transduction