Fanconi anemia A is a nucleocytoplasmic shuttling molecule required for gonadotropin-releasing hormone (GnRH) transduction of the GnRH receptor.
GnRH binds its cognate G protein-coupled GnRH receptor (GnRHR) located on pituitary gonadotropes and drives expression of gonadotropin hormones. There are two gonadotropin hormones, comprised of a common alpha- and hormone-specific beta-subunit, which are required for gonadal function. Recently we identified that Fanconi anemia a (Fanca), a DNA damage repair gene, is differentially expressed within the LbetaT2 gonadotrope cell line in response to stimulation with GnRH. FANCA is mutated in more than 60% of cases of Fanconi anemia (FA), a rare genetically heterogeneous autosomal recessive disorder characterized by bone marrow failure, endocrine tissue cancer susceptibility, and infertility. Here we show that induction of FANCA protein is mediated by the GnRHR and that the protein constitutively adopts a nucleocytoplasmic intracellular distribution pattern. Using inhibitors to block nuclear import and export and a GnRHR antagonist, we demonstrated that GnRH induces nuclear accumulation of FANCA and green fluorescent protein (GFP)-FANCA before exporting back to the cytoplasm using the nuclear export receptor CRM1. Using FANCA point mutations that locate GFP-FANCA to the cytoplasm (H1110P) or functionally uncouple GFP-FANCA (Q1128E) from the wild-type nucleocytoplasmic distribution pattern, we demonstrated that wild-type FANCA was required for GnRH-induced activation of gonadotrope cell markers. Cotransfection of H1110P and Q1128E blocked GnRH activation of the alphaGsu and GnRHR but not the beta-subunit gene promoters. We conclude that nucleocytoplasmic shuttling of FANCA is required for GnRH transduction of the alphaGSU and GnRHR gene promoters and propose that FANCA functions as a GnRH-induced signal transducer.
Larder
Rachel
R
Medical Research Council, Human Reproductive Sciences Unit, Centre for Reproductive Biology, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4JT, Scotland, United Kingdom.
Karali
Dimitra
D
Nelson
Nancy
N
Brown
Pamela
P
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D052217:Fanconi Anemia Complementation Group A Protein / Q000378:metabolism / Q000502:physiology*; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000502:physiology; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics; D050506:Mutant Chimeric Proteins / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism*; D014018:Tissue Distribution; D000097606:Exportin 1 Protein
D052217:Fanconi Anemia Complementation Group A Protein; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D007987:Gonadotropin-Releasing Hormone; D049452:Green Fluorescent Proteins; D028884:Karyopherins; D037101:Luteinizing Hormone, beta Subunit; D050506:Mutant Chimeric Proteins; D029543:Nucleocytoplasmic Transport Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011966:Receptors, LHRH; D000097606:Exportin 1 Protein; C498471:FANCA protein, human