Neuronal microtubule-associated protein 2D is a dual a-kinase anchoring protein expressed in rat ovarian granulosa cells.
A-kinase anchoring proteins (AKAPs) function to target protein kinase A (PKA) to specific locations within the cell. AKAPs are functionally identified by their ability to bind the type II regulatory subunits (RII) of PKA in an in vitro overlay assay. We previously showed that follicle-stimulating hormone (FSH) induces the expression of an 80-kDa AKAP (AKAP 80) in ovarian granulosa cells as they mature from a preantral to a preovulatory phenotype. In this report, we identify AKAP 80 as microtubule-associated protein 2D (MAP2D), a low molecular weight splice variant of the neuronal MAP2 protein. MAP2D is induced in granulosa cells by dexamethasone and by FSH in a time-dependent manner that mimics that of AKAP 80, and immunoprecipitation of MAP2D depletes extracts of AKAP 80. MAP2D is the only MAP2 protein present in ovaries and is localized to granulosa cells of preovulatory follicles and to luteal cells. MAP2D is concentrated at the Golgi apparatus along with RI and RII and, based on coimmunoprecipitation results, appears to bind both RI and RII in granulosa cells. Reduced expression of MAP2D resulting from treatment of granulosa cells with antisense oligonucleotides to MAP2 inhibited the phosphorylation of cAMP-response element-binding protein. These results suggest that this classic neuronal RII AKAP is a dual RI/RII AKAP that performs unique functions in ovarian granulosa cells that contribute to the preovulatory phenotype.
Salvador
Lisa M
LM
Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
Flynn
Maxfield P
MP
Avila
Jesús
J
Reierstad
Scott
S
Maizels
Evelyn T
ET
Alam
Hena
H
Park
Youngkyu
Y
Scott
John D
JD
Carr
Daniel W
DW
Hunzicker-Dunn
Mary
M
D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010053:Ovary / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010766:Phosphorylation; D020033:Protein Isoforms; D051381:Rats; D017207:Rats, Sprague-Dawley; D011974:Receptors, LH / Q000378:metabolism
D002352:Carrier Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011974:Receptors, LH; D003907:Dexamethasone; D005640:Follicle Stimulating Hormone