Transglutaminases (EC 2.3.2.13 ) are a family of enzymes that catalyze the crosslinking of proteins by epsilon-gamma
glutamyl lysine isopeptide bonds. The transglutaminases include factor XIII (plasma transglutaminase; 134570),
keratinocyte transglutaminase (TGM1; 190195), hair follicle transglutaminase, prostate transglutaminase (TGM4;
600585), and tissue transglutaminase (TGM2). Although the overall primary structures of these enzymes appear to be
quite different, they all share a common amino acid sequence at the active site (Y-G-Q-C-W) and a strict calcium
dependence for their activity. The differences in the primary structures of these different transglutaminases are probably
responsible for the diverse biologic functions that they play in physiologic processes such as blood coagulation,
epidermal differentiation, seminal fluid coagulation and fertilization, cell differentiation, and apoptosis.
General function
Apoptosis, Enzyme
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Cellular localization
Secreted, Plasma membrane
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Ovarian function
Oocyte maturation
Comment
Kim SW, et al 2001 investigated the function of tissue transglutaminase (tTG) in
the germinal vesicle breakdown (GVBD) of mouse oocyte. tTG was identified in
ooplasm and germinal vesicle by immunostaining with less amount in germinal
vesicle. Spontaneous maturation of the oocytes elevated in situ activity of
tTG by over 2.5-fold at 3 h, which was determined by a confocal microscopic
assay. However, incubation with monodansylcadaverine (MDC), a tTG inhibitor,
blocked the activation of tTG. The possible role of tTG in GVBD was
investigated by the use of two tTG inhibitors, MDC and cystamine. MDC largely
inhibited the GVBD by a concentration-dependent manner. GV-stage oocytes were
matured to the GVBD stage by 78% at 3 h in the normal culture condition.
However, in the oocytes incubated with MDC for 3 h, the GVBD rates were 43 and
11% by 50 and 100 muM, respectively. MDC also blocked the entry of 70 kDa
RITC-dextran from the ooplasm to the compartment of germinal vesicle,
indicating a possible inhibition of nuclear pore disassembly by MDC. The role
of tTG in GVBD was further investigated by microinjection with cystamine. The
control oocytes, injected with DPBS, showed about 80% of GVBD at 3 h. But the
oocytes injected with cystamine showed 15% of GVBD at 3 h and a little higher
rate at 6 h. In addition, the inhibition of GVBD maturation by MDC was
reversible by washing. These results suggested that tTG was involved in the
early event of mouse oocyte maturation.
Expression regulated by
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Ovarian localization
Oocyte, Cumulus, Granulosa
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Changes in granulosa cells gene expression associated with growth, plateau and atretic phases in medium bovine follicles. Douville G 2014 et al.
BACKGROUND
The objective of this study was to build the transcriptomic profile of granulosa cells originating from follicles 6 to 9mm in diameter in dairy cattle using microarrays.
METHODS
GRANULOSA CELLS ORIGINATING FROM THREE DIFFERENT PHASES OF ANTRAL FOLLICLE GROWTH WERE COMPARED: growing (G), plateau (P) and atresia (A), as categorized by flow cytometry profiles of DNA. The growing and atretic conditions were each hybridized against the plateau condition as a reference in order to understand the specific biological mechanisms modulated in this class of follicles.
RESULTS
2,942 genes were differentially expressed in P vs. G and 1,974 in A vs. P. A clear segregation of the 3 phases was confirmed by between group analysis (BGA). The first characteristic of the plateau phase is the activation of the upstream regulators TP53 and PTEN which participate in the reduction of cell growth through MYC, FOS and E2F1-2-3. We also observed the down-regulation of steroidogenesis genes: CYP11A1 and CYP19A1, in the granulosa cells of the plateau phase relative to the growth phase. On the other hand, the A vs. P contrast showed up-regulation of multiple transcripts associated to apoptosis: CCT2, DAB2, DSG2 and TGM2.
CONCLUSIONS
This study offers multiple candidate genes to be further studied in order to elucidate their role in the modulation of follicular development and, ultimately, of oocyte quality.
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Differential expression of tissue transglutaminase protein in mouse ovarian
follicle Lee CJ, .
Tissue transglutaminase (tTG) protein begins to accumulate in apoptotic cells and its mRNA is
expressed at the onset of apoptotic change. In the present study, we compared tTG expression with
the atretic degree of mouse ovarian follicles. The whole-body gamma-irradiated mouse ovaries
were collected and immunohistochemistry for tTG and in situ 3'-end labeling (TUNEL) was
performed. Based on the identification of atretic follicles with hematoxylin-eosin and TUNEL
immunostaining, tTG expression was evaluated and compared between normal (NF) and atretic
follicles (AF). The expression of tTG was different among AF depending on the degree of atretic
changes. There was a strong association of tTG expression with the follicular apoptotic changes.
Among NF, 24% of follicles expressed tTG protein. This value, however, increased up to 66% in
atretic follicles. The present results suggest that the follicular expression of tTG is closely related to
the degree of follicle atresia. Therefore, the expression of tTG can be used as a useful marker for
the identification of atretic follicles in the ovary.
Follicle stages
Primordial
Comment
Arraztoa JA, et al 2005 reported the identification of genes expressed in primate primordial oocytes.