NCBI Summary:
Laminins, a family of extracellular matrix glycoproteins, are the major noncollagenous constituent of basement membranes. They have been implicated in a wide variety of biological processes including cell adhesion, differentiation, migration, signaling, neurite outgrowth and metastasis. Laminins, composed of 3 non identical chains: laminin alpha, beta and gamma (formerly A, B1, and B2, respectively), form a cruciform structure consisting of 3 short arms, each formed by a different chain, and a long arm composed of all 3 chains. Each laminin chain is a multidomain protein encoded by a distinct gene. Several isoforms of each chain have been described. Different alpha, beta and gamma chain isomers combine to give rise to different heterotrimeric laminin isoforms which are designated by Arabic numerals in the order of their discovery, i.e. alpha1beta1gamma1 heterotrimer is laminin 1. The biological functions of the different chains and trimer molecules are largely unknown, but some of the chains have been shown to differ with respect to their tissue distribution, presumably reflecting diverse functions in vivo. This gene encodes the beta chain isoform laminin, beta 2. The beta 2 chain contains the 7 structural domains typical of beta chains of laminin, including the short alpha region. However, unlike beta 1 chain, beta 2 has a more restricted tissue distribution. It is enriched in the basement membrane of muscles at the neuromuscular junctions, kidney glomerulus and vascular smooth muscle. Transgenic mice in which the beta 2 chain gene was inactivated by homologous recombination, showed defects in the maturation of neuromuscular junctions and impairment of glomerular filtration. Alternative splicing involving a non consensus 5' splice site (gc) in the 5' UTR of this gene has been reported. It was suggested that inefficient splicing of this first intron, which does not change the protein sequence, results in a greater abundance of the unspliced form of the transcript than the spliced form. The full-length nature of the spliced transcript is not known. [provided by RefSeq, Aug 2011]
General function
Cell adhesion molecule
Comment
Cellular localization
Extracellular Matrix
Comment
Ovarian function
Follicle development
Comment
Proteomic biomarkers for ovarian cancer risk in women with polycystic ovary syndrome: a systematic review and biomarker database integration. Galazis N et al. OBJECTIVE: To review and identify possible biomarkers for ovarian cancer (OC) in women with polycystic ovary syndrome (PCOS). DESIGN: Systematic literature searches of MEDLINE, EMBASE, and Cochrane using the search terms 'proteomics,' 'proteomic,' and 'ovarian cancer' or 'ovarian carcinoma.' Proteomic biomarkers for OC were then integrated with an updated previously published database of all proteomic biomarkers identified to date in patients with PCOS. SETTING: Academic department of obstetrics and gynecology in the United Kingdom. PATIENT(S): A total of 180 women identified in the six studies. INTERVENTION(S): Tissue samples from women with OC vs. tissue samples from women without OC. MAIN OUTCOME MEASURE(S): Proteomic biomarkers, proteomic technique used, and methodologic quality score. RESULT(S): A panel of six biomarkers was overexpressed both in women with OC and in women with PCOS. These biomarkers include calreticulin, fibrinogen-?, superoxide dismutase, vimentin, malate dehydrogenase, and lamin B2. CONCLUSION(S): These biomarkers could help improve our understanding of the links between PCOS and OC and could potentially be used to identify subgroups of women with PCOS at increased risk of OC. More studies are required to further evaluate the role these biomarkers play in women with PCOS and OC.
Expression regulated by
Comment
Ovarian localization
Comment
Follicle stages
Primary, Secondary, Antral, Preovulatory
Comment
Extracellular matrix of the developing ovarian follicle.
Rodgers RJ, et al 2003 ..
Ovaries can be considered tissues in which endocrine organs - follicles and corpora lutea - continually grow and regress. Follicles have both epithelial and stromal layers in which cell migration or movement, cell division, specialization and differentiation, and death occur. A fluid-filled antrum develops and at ovulation the epithelial cells undergo an epithelial to mesenchymal transition into luteal cells. Although growth factors and hormones are very important in some of these processes, the extracellular matrix participates in all of them. Importantly, the matrix is diverse in composition and cells rarely behave without reference to the composition and structure of the matrix. When follicles commence growing, the follicular basal lamina changes in its composition from containing all six alpha chains of collagen type IV to only alpha1 and alpha2. Perlecan and nidogen 1 subsequently become components of the follicular basal lamina, and there is an increase in the amount of laminin chains alpha1, beta2 and gamma1, at least in cows. Late in follicular developent and on atresia some follicles contain laminin alpha2. On atresia the follicular basal lamina is not degraded as occurs at ovulation, but can be breached by cells from the thecal layer if granulosa cells no longer align it.