Human follicle-stimulating hormone (FSH) receptor interacts with the adaptor protein APPL1 in HEK 293 cells: potential involvement of the PI3K pathway in FSH signaling.
Selection of a dominant follicle that will ovulate likely occurs by activation of cell survival pathways and suppression of death-promoting pathways in a mechanism involving FSH and its cognate receptor (FSHR). A yeast two-hybrid screen of an ovarian cDNA library was employed to identify potential interacting partners with human FSHR intracellular loops 1 and 2. Among eight cDNA clones identified in the screen, APPL1 (adaptor protein containing PH domain, PTB domain, and leucine zipper motif; also known as APPL or DIP13alpha) was chosen for further analysis. APPL1 appears to coimmunoprecipitate with FSHR in HEK 293 cells stably expressing FSHR (293/FSHR cells), confirming APPL1 as a potential FSHR-interacting partner. The phosphorylation status of members of the phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway was also examined because of the proposed role of APPL1 in the antiapoptotic PI3K/Akt pathway. FOXO1a, also referred to as forkhead homologue in rhabdomyosarcoma, is a downstream effector in the pathway and tightly linked to expression of proapoptotic genes. FOXO1a, but not the upstream kinase Akt, is rapidly phosphorylated, and FOXO1a is thereby inactivated when 293/FSHR cells are treated with FSH. In addition, FSHR coimmunoprecipitates with Akt. The identification of APPL1 as a potential interactor with FSHR and the finding that FOXO1a is phosphorylated in response to FSH provide a possible link between FSH and PI3K/Akt signaling, which may help to delineate a survival mechanism whereby FSH selects the dominant follicle to survive.
Nechamen
Cheryl A
CA
Wadsworth Center, David Axelrod Institute for Public Health, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12208, USA.
Thomas
Richard M
RM
Cohen
Brian D
BD
Acevedo
Giselles
G
Poulikakos
Poulikos I
PI
Testa
Joseph R
JR
Dias
James A
JA
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D005640:Follicle Stimulating Hormone / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000166:cytology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011962:Receptors, FSH / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D005640:Follicle Stimulating Hormone; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011962:Receptors, FSH; D043562:Receptors, G-Protein-Coupled; C464801:APPL1 protein, human; C494918:AKT1 protein, human