Boise et al. (1993) isolated a BCL2-related gene, which they designated BCLX, and showed that it can function as a BCL2-independent regulator of apoptosis. Alternative splicing resulted in 2 distinct BCLX mRNAs. The protein product of the larger mRNA (BCLXL) was similar in size and predicted structure to BCL2. When stably transfected into an IL3-dependent cell line, it inhibited cell death upon growth factor withdrawal at least as well as BCL2. Unexpectedly, the smaller mRNA species (BCLXS) encodes a protein that inhibits the ability of BCL2 to enhance the survival of growth factor-deprived cells.
NCBI Summary:
The protein encoded by this gene belongs to the BCL-2 protein family. BCL-2 family members form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. The proteins encoded by this gene are located at the outer mitochondrial membrane, and have been shown to regulate outer mitochondrial membrane channel (VDAC) opening. VDAC regulates mitochondrial membrane potential, and thus controls the production of reactive oxygen species and release of cytochrome C by mitochondria, both of which are the potent inducers of cell apoptosis. Two alternatively spliced transcript variants, which encode distinct isoforms, have been reported. The longer isoform acts as an apoptotic inhibitor and the shorter form acts as an apoptotic activator.
General function
Cell death/survival, Anti-apoptotic, Apoptosis
Comment
Shimizu et al. (1999) created liposomes that carried the mitochondrial porin channel VDAC to show that the recombinant proapoptotic proteins Bax and Bak accelerate the opening of VDAC, whereas the antiapoptotic protein BCLXL closes VDAC by binding to it directly. Bax and Bak allow cytochrome c to pass through VDAC out of liposomes, but passage is prevented by BCLXL.
Goodman et al. (1998) reported that Northern blot analysis revealed an increase in bax mRNA levels and a decrease in bcl-x mRNA levels coincident with luteal cell apoptosis in rabbbits induced by estradiol withdrawal.
Gene whose expression is detected by cDNA array hybridization: GDP/GTP exchangers, GTPase stimulators and inhibitors, apoptosis. Also, relative transcript level reproducibly decreases during IVM Rozenn Dalbi?Tran and Pascal Mermilloda
Johnson et al. (1999) reported that 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. Kugu et al. (1998) reported that messenger RNA transcripts encoded by the bcl-xlong survival gene and the bcl-xshort pro-apoptosis gene were detected by Northern blot analysis of total RNA prepared either from human ovaries or from Percoll-purified granulosa-lutein cells obtained from patients.
Wehrli et al. (1998) reported immunohistochemical staining of bcl-2, bax, mcl-1, and bcl-X expression in ovarian surface epithelial tumors.
Follicle stages
Antral, Preovulatory, Corpus luteum
Comment
Genome-wide identification ofaberrantly methylated promoters inovarian tissue of prenatally androgenized rats. Zhang D 2014 et al.
OBJECTIVE
To identify aberrantly methylated candidate genes that are involved in the development of polycystic ovary syndrome (PCOS).
DESIGN
Animal model.
SETTING
University-affiliated laboratory.
ANIMAL(S)
Sprague-Dawley rats.
INTERVENTION(S)
The prenatally androgenized (PNA) rat model was established. Pregnant rats were treated with daily SC injections of T propionate during late gestation, and their female offspring were studied as adults.
MAIN OUTCOME MEASURE(S)
Serum glucose and hormone levels, ovary morphology and cell apoptosis, genome-wide CpG methylation, and expression of caspase-3 protein were measured.
RESULT(S)
In the PNA group, the levels of serum glucose, 17-hydroxyprogesterone, and T were significantly higher when compared with the control group. Ovarian morphology showed increased atretic follicles and cystic follicles. Using the MeDIP-chip approach, we identified 528 genes that were hypermethylated in PNA ovaries. Gene ontology analyses revealed that these genes are involved in a variety of reproductive development and biological processes. The methylation enrichments of Bcl2l1 and Scr5a1 observed in the PNA group by MeDIP-quantitative polymerase chain reaction assay were significantly higher than those obtained from the control group. Furthermore, the mRNA level of the Bcl2l1 gene was significantly decreased in the PNA group. The percentage of caspase-3-positive cells in the PNA group was obviously higher compared with the control group, by terminal deoxynucleotidyl transferase dUTP nick end labeling detection as well.
CONCLUSION(S)
DNA methylation alteration may be an important factor affecting the genes involved in the pathophysiological processes that result in the phenotype of PCOS.
/////////////////////////
Phenotypes
Mutations
2 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: embryonic lethal Comment:Motoyama et al. (1995) reported that Bcl-x-deficient mice died around embryonic day 13. Extensive apoptotic cell death was evident in postmitotic immature neurons of the developing brain, spinal cord, and dorsal root ganglia. Hematopoietic cells in the liver were also apoptotic.
Species: mouse
Mutation name: None
type: null mutation fertility: fertile Comment:Riedlinger G, et al 2002 reported that
Bcl-x Is Not Required for Maintenance of Follicles and Corpus
Luteum in the Postnatal Mouse Ovary.
It has been demonstrated that the survival of mouse primordial germ
cells during embryogenesis depends on the presence of Bcl-x. The authors
investigated whether, in the mouse, Bcl-x is required for the postnatal maintenance of
follicles and luteal cells, and whether Stat5 activates the bcl-x gene. The bcl-x gene was
deleted in these cells within the mouse using Cre-loxP recombination. Loss of the bcl-x
gene did not affect the numbers of primordial, primary, and antral follicles.
Furthermore, expression of the bcl-x gene in the ovary was independent of Stat5 and
its activating hormone, prolactin. To determine whether the prolactin receptor (PrlR),
Stat5, and Bcl-x were required for establishment and maintenance of the corpus luteum,
The authors induced pseudopregnancies in the respective gene-deletion mice. Whereas luteal
cells underwent apoptosis in the absence of the PrlR, no changes were observed in the
absence of Stat5 or Bcl-x.