Entactin, a 150-kD sulfated glycoprotein, is a major component of basement membranes and forms a highly stable
noncovalent complex with laminin. Nidogen can serve as a bridge between the 2 most abundant
molecules in the basement membrane: type IV collagen and laminin.
General function
Cell adhesion molecule
Comment
Cellular localization
Extracellular Matrix, Secreted
Comment
Ovarian function
Comment
Asem EK, et al 2000 reported the identification of different components of basal lamina of avian ovarian follicle.
Pure and intact basal lamina was isolated from preovulatory
follicles of the chicken ovary. Some components of the basal lamina could be
solubilized with guanidine-HCl (designated Fraction 1) and remaining
components with beta-mercaptomethanol containing guanidine-HU (designated
Fraction 2). With Western blot analysis, monoclonal and polyclonal antibodies
raised against avian, mammalian, and human proteins recognized proteins in
Fractions 1 and 2 of solubilized basal lamina. Thus, antibodies raised against
extracellular matrix proteins, laminin, fibronectin, entactin/nidogen,
tenascin, heparan sulfate proteoglycan, osteonectin, and Type IV collagen
reacted positively with basal lamina proteins.
Identification of Sheep Ovary Genes Potentially Associated with Off-season Reproduction. Chen L et al. Off-season reproduction is a favorable economic trait for sheep industry. Hu sheep, an indigenous Chinese sheep breed, demonstrates a higher productivity of lambs and displays year-around oestrous behavior under proper nutrition and environment. The genetic basis behind these traits, however, is not well understood. In order to identify genes associated with the off-season reproduction, we constructed a suppression subtractive hybridization (SSH) cDNA library using pooled ovary mRNAs of 6 oestrous Hu females as a tester and the pooled ovary mRNAs of 6 non-oestrous Chinese Merino females as a driver. A total of 382 resulting positive clones were obtained after the SSH. We identified 114 differentially up-regulated genes in oestrous Hu sheep by using subsequent screening and DNA sequencing, of which 8 were previously known, 93 were reported for the first time in sheep, and 13 were novel with no significant homology to any sequence in the DNA databases. Functions of the genes identified are related to cell division, signal transduction, structure, metabolism, or cell defense. To validate the results of SSH, 6 genes (Ntrk2, Ppap2b, Htra1, Nid1, Serpine2 and Foxola) were selected for conformational analysis using quantitative real-time PCR (qRT-PCR), and two of them (Htral and Foxo1a) were verified by Northern blot. All of the 6 genes were differentially up-regulated in the ovary of oestrous Hu. It is obvious that off-season reproduction is a complex trait involving multiple genes in multiple organs. This study helps to provide a foundation for the final identification of functional genes involved in the sheep ovary.
Expression regulated by
Steroids
Comment
Expression of Extracellular Matrix Components Is Disrupted in the Immature and Adult Estrogen Receptor ?Null Mouse Ovary. Zalewski A et al. Within the ovary, Estrogen Receptor ?(ER? is localized to the granulosa cells of growing follicles. 17?estradiol (E2) acting via ER?augments the actions of follicle stimulating hormone in granulosa cells, leading to granulosa cell differentiation and formation of a preovulatory follicle. Adult ER?null females are subfertile and possess ovaries with reduced numbers of growing follicles and corpora lutea. Because the majority of E2 production by granulosa cells occurs once puberty is reached, a role for ER?in the ovary prior to puberty has not been well examined. We now provide evidence that lack of ER?disrupts gene expression as early as post-natal day (PND) 13, and in particular, we identify a number of genes of the extracellular matrix (ECM) that are significantly higher in ER?null follicles than in wildtype (WT) follicles. Considerable changes occur to the ECM occur during normal folliculogenesis to allow for the dramatic growth, cellular differentiation, and reorganization of the follicle from the primary to preovulatory stage. Using quantitative PCR and immunofluorescence, we now show that several ECM genes are aberrantly overexpressed in ER?null follicles. We find that Collagen11a1, a protein highly expressed in cartilage, is significantly higher in ER?null follicles than WT follicles as early as PND 13, and this heightened expression continues through PND 23-29 into adulthood. Similarly, Nidogen 2, a highly conserved basement membrane glycoprotein, is elevated in ER?null follicles at PND 13 into adulthood, and is elevated specifically in the ER?null focimatrix, a basal lamina-like matrix located between granulosa cells. Focimatrix laminin and Collagen IV expression were also higher in ER?null ovaries than in WT ovaries at various ages. Our findings suggest two novel observations: a) that ER?regulates granulosa cell gene expression ovary prior to puberty, and b) that ER?regulates expression of ECM components in the mouse ovary.
Ovarian localization
Granulosa, Follicular Fluid
Comment
Studies of granulosa cell maturation in dominant and subordinate bovine follicles: novel extracellular matrix focimatrix is co-ordinately regulated with cholesterol side-chain cleavage CYP11A1. Irving-Rodgers HF 2009 et al.
During growth of antral ovarian follicles granulosa cells first become associated with a novel type of extracellular matrix, focimatrix, and at larger sizes follicles become either subordinate or dominant. To examine this, bovine subordinate (9.0+/-S.E.M. 0.4 mm; n=16), partially dominant (12.0+/-0.6 mm; n=18) and fully dominant (15.0+/-0.4 mm; n=14) follicles were examined by real time RT-PCR analyses of granulosa cells and by immunohistochemistry of focimatrix. Changes in the expression of FSH receptor, LH receptor, cholesterol side-chain cleavage (CYP11A1), 3beta-hydroxysteroid dehydrogenase, aromatase (CYP19A1) and inhibin-alpha and beta-B were observed as expected for follicle sizes examined. After adjusting for size differences, only CYP11A1 was significantly different between the groups, and elevated in dominant follicles. Also after adjusting for differences in size there were no significant differences in expression of focimatrix components collagen type IV alpha-1 (COL4A1), laminin beta-2, nidogen 1 (NID1), and perlecan (HSPG2) or the volume density of NID1 and -2 and HSPG2. The volume density of focimatrix components in laminin 111 was significantly elevated in dominant follicles. Adjusting for analysis of more than one follicle per animal and for multiple correlations, CYP11A1 mRNA levels were highly correlated with the focimatrix genes COL4A1, NID1 and -2 and HSPG2. Thus, focimatrix may potentially regulate CYP11A1 expression, and the regulation of both could be important in follicular dominance.
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McArthur ME, et al 2000 reported the identification and immunolocalization of decorin, versican,
perlecan, nidogen, and chondroitin sulfate proteoglycans in bovine
small-antral ovarian follicles.
Proteoglycans (PGs) consist of a core protein and attached glycosaminoglycans (GAGs)
and have diverse roles in cell and tissue biology. In follicles PGs have been detected only
in follicular fluid and in cultured granulosa cells, and the composition of their GAGs has
been determined. To identify PGs in whole ovarian follicles, not just in follicular fluid and
granulosa cells, small (1-3-mm) bovine follicles were harvested. A proportion of these was
incubated with (35)SO(4) for 24 h to incorporate radiolabel into the GAGs. The freshly
harvested and cultured follicles were sequentially extracted with 6 M urea buffer, the same
buffer with 0.1% Triton X-100 and then with 0.1 M NaOH. Proteoglycans were subjected
to ion-exchange and size-exclusion chromatography. The GAGs were analyzed by
chemical and enzymic digestion, and on the basis of their composition, a list of
known PGs was measured by ELISA analyses. Versican, perlecan, decorin, but not aggrecan
or biglycan, were identified. These, excluding decorin for technical reasons, as well as a
basal lamina glycoprotein, nidogen/entactin, were immunolocalized. Versican was localized
to the thecal layers, including externa and the interna particularly in an area adjacent to the
follicular basal lamina. Perlecan and nidogen were localized to the follicular basal lamina of
antral follicles, both healthy and atretic, but not to that of preantral follicles. Both were
localized to subendothelial basal laminas, but the former was not readily detected in
arteriole smooth muscle layers. This study has confirmed the presence of versican and
perlecan, but not the latter as a component of follicular fluid, and identified decorin and
nidogen in ovarian antral follicles.
Follicle stages
Antral, Preovulatory, Corpus luteum
Comment
Dynamics of extracellular matrix in ovarian follicles and corpora lutea of mice. Irving-Rodgers HF et al. Despite the mouse being an important laboratory species, little is known about changes in its extracellular matrix (ECM) during follicle and corpora lutea formation and regression. Follicle development was induced in mice (29 days of age/experimental day 0) by injections of pregnant mare's serum gonadotrophin on days 0 and 1 and ovulation was induced by injection of human chorionic gonadotrophin on day 2. Ovaries were collected for immunohistochemistry (n=10 per group) on days 0, 2 and 5. Another group was mated and ovaries were examined on day 11 (n=7). Collagen type IV alpha1 and alpha2, laminin alpha1, beta1 and gamma1 chains, nidogens 1 and 2 and perlecan were present in the follicular basal lamina of all developmental stages. Collagen type XVIII was only found in basal lamina of primordial, primary and some preantral follicles, whereas laminin alpha2 was only detected in some preantral and antral follicles. The focimatrix, a specialised matrix of the membrana granulosa, contained collagen type IV alpha1 and alpha2, laminin alpha1, beta1 and gamma1 chains, nidogens 1 and 2, perlecan and collagen type XVIII. In the corpora lutea, staining was restricted to capillary sub-endothelial basal laminas containing collagen type IV alpha1 and alpha2, laminin alpha1, beta1 and gamma1 chains, nidogens 1 and 2, perlecan and collagen type XVIII. Laminins alpha4 and alpha5 were not immunolocalised to any structure in the mouse ovary. The ECM composition of the mouse ovary has similarities to, but also major differences from, other species with respect to nidogens 1 and 2 and perlecan.