The γ3 chain of laminin is widely but differentially expressed in murine basement membranes: expression and functional studies.

Laminins are heterotrimeric extracellular glycoproteins found in, but not confined to, basement membranes (BMs). They are important components in formation of the molecular networks of BMs as well as in cell polarity, cell differentiation and tissue morphogenesis. Each laminin is composed by an α, a β and a γ chain.

Expression of type XXIII collagen mRNA and protein.

Collagen XXIII is a member of the transmembranous subfamily of collagens containing a cytoplasmic domain, a membrane-spanning hydrophobic domain, and three extracellular triple helical collagenous domains interspersed with non-collagenous domains. We cloned mouse, chicken, and humanalpha1(XXIII) collagen cDNAs and showed that this non-abundant collagen has a limited tissue distribution in non-tumor tissues. Lung, cornea, brain, skin, tendon, and kidney are the major sites of expression.

A novel marker of tissue junctions, collagen XXII.

Here we describe a novel specific component of tissue junctions, collagen XXII. It was first identified by screening an EST data base and subsequently expressed as a recombinant protein and characterized as an authentic tissue component. The COL22A1 gene on human chromosome 8q24.

Matrix metalloproteinase 9 expression is coordinately modulated by the KRE-M9 and 12-O-tetradecanoyl-phorbol-13-acetate responsive elements.

To investigate the pathophysiologic role of matrix metalloproteinase 9 (MMP-9), we analyzed the mechanism of its transcriptional regulation in keratinocytes and in HT1080 fibrosarcoma cells in culture. The KRE-M9 element, which is located between the 12-O-tetradecanoyl-phorbol-13-acetate responsive element (TRE) and the transcription initiation site in the MMP-9 promoter, is essential for MMP-9 transcription in the absence of the TRE. The KRE-M9 binding protein, however, is shown to be a repressor of transcription rather than an activator; we found several times higher transcriptional activity when the KRE-M9 element was mutated.

Collagen XXIV, a vertebrate fibrillar collagen with structural features of invertebrate collagens: selective expression in developing cornea and bone.

Tissue-specific assembly of fibers composed of the major collagen types I and II depends in part on the formation of heterotypic fibrils, using the quantitatively minor collagens V and XI. Here we report the identification of a new fibrillar-like collagen chain that is related to the fibrillar alpha1(V), alpha1(XI), and alpha2(XI) collagen polypeptides and which is coexpressed with type I collagen in the developing bone and eye. The new collagen was designated the alpha1(XXIV) chain and consists of a long triple helical domain flanked by typical propeptide-like sequences.