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Department of Biological Sciences, The University of Notre Dame, Notre Dame, Indiana 46556
Address all correspondence and requests for reprints to: A. L. Johnson, Ph.D., Department of Biological Sciences, P.O. Box 369, The University of Notre Dame, Notre Dame, Indiana 46556. E-mail: johnson.128{at}nd.edu
Expression of Bcl-x protein was evaluated in hen ovarian follicles,
relative to stage of development, and in cultured granulosa cells after
treatment with various apoptosis-suppressing or -inducing agents. Using
Western blot analysis, Bcl-XLONG was most frequently
observed migrating as a doublet with a molecular mass of approximately
28 kDa; the apparent higher molecular mass band of this doublet was
determined to represent a phosphorylated form. Consistent with previous
findings reported for bcl-x messenger RNA, only
the Bcl-XLONG (apoptosis-suppressing) form of protein was
detected in the hen granulosa cells, and highest levels of
Bcl-XLONG protein (sum of the protein doublet) expression
were found in granulosa from preovulatory follicles together with
tissues with immune function (e.g. spleen and bone
marrow). Evidence for Bcl-XSHORT expression was found only
in the theca and several nonovarian tissues. Immunocytochemical
analysis of preovulatory vs. prehierarchal follicles
confirmed the comparatively greater expression of cytoplasmic
Bcl-XLONG, particularly in preovulatory follicle granulosa.
Levels of Bcl-XLONG were significantly increased after
20 h of culture in the presence of 8-bromo-cAMP (8-br-cAMP;
compared with culture in control medium) in granulosa cells from both
stages of follicle development. Such results are correlated with the
protein’s proposed function to protect against cell death in
apoptosis-resistant, preovulatory follicle granulosa cells and are
consistent with the ability of this cAMP agonist to increase
bcl-XLONG messenger RNA levels in cultured
cells. Furthermore, several factors that have previously been
demonstrated to suppress apoptosis in granulosa cells, in
vitro, (e.g. 8-br-cAMP, LH, FSH) were found to
rapidly (within 15 min) increase levels of phosphorylated
Bcl-XLONG, compared with control cells, whereas an
inhibitor of protein kinase A (H-89) blocked such phosphorylation. By
comparison, transforming growth factor 
, a factor previously found
to attenuate apoptosis and apoptosis-inducing agents
(e.g. paclitaxel, C8-ceramide, daunorubicin, UV
irradiation) failed to phosphorylate Bcl-XLONG. From these
studies, it is concluded that both the phosphorylation of
Bcl-XLONG (a short-term response) and increased levels of
Bcl-XLONG (a comparatively slower response) in hen
granulosa cells are promoted by gonadotropins via the adenylyl
cyclase/cAMP signaling pathway. Moreover, elevated levels of chicken
Bcl-XLONG protein expression and its phosphorylated state
are correlated with resistance to apoptotic cell death in granulosa
cells in vitro and ultimately a resistance to ovarian
follicle atresia in vivo.
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 D. C. Woods and A.L. Johnson Regulation of Follicle-Stimulating Hormone-Receptor Messenger RNA in Hen Granulosa Cells Relative to Follicle Selection Biol Reprod, March 1, 2005; 72(3): 643 - 650. [Abstract] [Full Text] [PDF]
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 A. L. Johnson, J. S. Langer, and J. T. Bridgham Survivin as a Cell Cycle-Related and Antiapoptotic Protein in Granulosa Cells Endocrinology, September 1, 2002; 143(9): 3405 - 3413. [Abstract] [Full Text] [PDF]
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G. Riedlinger, R. Okagaki, K.-U. Wagner, E. B. Rucker III, T. Oka, K. Miyoshi, J. A. Flaws, and L. Hennighausen Bcl-x Is Not Required for Maintenance of Follicles and Corpus Luteum in the Postnatal Mouse Ovary Biol Reprod, February 1, 2002; 66(2): 438 - 444. [Abstract] [Full Text] [PDF]
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S.-Y. Chun, H.-W. Bae, W.-J. Kim, J.-H. Park, S. Y. Hsu, and A. J. W. Hsueh Expression of Messenger Ribonucleic Acid for the Antiapoptosis Gene P11 in the Rat Ovary: Gonadotropin Stimulation in Granulosa Cells of Preovulatory Follicles Endocrinology, June 1, 2001; 142(6): 2311 - 2317. [Abstract] [Full Text] [PDF]
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A.L. Johnson, J.T. Bridgham, and J.A. Swenson Activation of the Akt/Protein Kinase B Signaling Pathway Is Associated with Granulosa Cell Survival Biol Reprod, May 1, 2001; 64(5): 1566 - 1574. [Abstract] [Full Text]
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A.L. Johnson and J.T. Bridgham Caspase-3 and -6 Expression and Enzyme Activity in Hen Granulosa Cells Biol Reprod, March 1, 2000; 62(3): 589 - 598. [Abstract] [Full Text]
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A. L. Johnson Editorial: Mcl-1--Just Another Antiapoptotic Bcl-2 Homolog? Endocrinology, December 1, 1999; 140(12): 5465 - 5468. [Full Text]
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