Mukae et al. (1998) cloned and characterized a DNase that can be activated by Caspase 3 and is involved in the degradation of chromosomal DNA into nucleosomal units during apoptosis. The cDNA of human caspase-activated DNase (CAD) was found to be expressed in cells that easily undergo DNA fragmentation in response to apoptotic stimuli, but not in those that do not show apoptotic DNA fragmentation. Introduction of a CAD expression vector resulted in enhanced DNA fragmentation. The expression of the CAD mRNA in human cell lines correlated with their ability to show DNA fragmentation during apoptosis. Overexpression of CAD potentiated DNA fragmentation by apoptotic stimuli in these cell lines, indicating that CAD is responsible for the apoptotic DNA degradation.
The DNA fragmentation factor (DFF) described by Liu et al. (1997) is a heterodimer of 40-kD (DFFB) and 45-kD (DFFA) subunits. The authors showed that DFFA is the substrate for caspase-3 and triggers DNA fragmentation during apoptosis.
General function
Cell death/survival, Apoptosis
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Follicle atresia, Luteolysis
Comment
Expression regulated by
Comment
Ovarian localization
Granulosa
Comment
The CAD mRNA was expressed in a limited number of human tissues, including pancreas, spleen, prostate, and ovary (Mukae et al., 1998).
Izawa et al. (1998) used reverse transcription polymerase chain reaction and
Western blotting for the analysis of apoptosis-related gene products. The
expression of caspase-1, caspase-3, DNA fragmentation factor (DFF or CAD),
and apoptotic protease activating factor-1 was demonstrated in granulosa cells from patients undergoing IVF.
Follicle stages
Antral, Preovulatory
Comment
Identification of Genes Involved in Apoptosis and Dominant Follicle Development During Follicular Waves in Cattle.
Evans AC, et al 2004 hypothesize that granulosa and theca cells from growing dominant follicles, with relatively high intrafollicular concentrations of estradiol, have a greater expression of genes involved in inhibiting apoptosis pathways and lower expression of genes involved in apoptosis pathways than growing subordinate follicles with lower estradiol concentrations. Using the well-characterized bovine dominant follicle model, they collected granulosa and theca cells from individual dominant and the largest subordinate follicle 3 days after initiation of a follicular wave in four animals. Based on ultrasound analysis, both follicle types were in the growth phase at the time of ovariectomy. However, dominant follicles were larger (9.8+/-1.0 versus 7.6+/-0.6 mm in diameter, P<0.05) and had greater intrafollicular concentrations of estradiol ( P<0.05) compared with the largest subordinate follicles. They used bovine cDNA microarrays, which contained a total of 1400 genes including a subset of 53 genes known to be involved in apoptosis pathways, to determine which apoptosis and marker genes from each of the four dominant versus subordinate follicles were potentially differentially expressed. Using a low stringency-screening criterion, 22 genes were identified. Quantitative real-time PCR confirmed that 16 of these genes were differentially expressed. The high intrafollicular concentrations of estradiol in growing dominant follicles were positively associated with enhanced expression of mRNAs in granulosa cells for aromatase, LH receptor, estradiol receptor beta, DICE-1 and MCL-1 compared with granulosa cells from subordinate follicles (all survival-associated genes). In contrast, the relatively low intrafollicular concentrations of estradiol in growing subordinate follicles were positively associated with enhanced expression of mRNAs in granulosa cells for beta glycan, COX-1, TNFalpha, CAD and DRAK-2, and in theca cells for beta glycan, caspase 13, P58(IPK), Apaf-1, BTG-3, and TS-BCLL compared with granulosa or theca cells from dominant follicles (genes that are all associated with cell death and/or apoptosis). These genes may be candidate estradiol target genes and that they may be early markers for the final stages of follicle differentiation and initiation of apoptosis and thus selection of dominant follicles during follicular waves.