Differentiation-dependent alternative splicing and expression of the extracellular matrix protein 1 gene in human keratinocytes

Lipoid proteinosis

Lipoid proteinosis is a rare, autosomal recessive disorder that presents in early infancy with hoarseness, followed by pox-like and acneiform scars, along with infiltration and thickening of the skin and certain mucous membranes. Histological and ultrastructural examination reveals widespread deposition of hyaline-like material and disruption/reduplication of basement membrane around blood vessels and at the dermal--epidermal junction. Recently, lipoid proteinosis was mapped to 1q21 and pathogenetic loss-of-function mutations were identified in the extracellular matrix protein 1 gene (ECM1). This article reviews the molecular basis of lipoid proteinosis and reassesses the clinico-pathological features of this disorder in light of the new genetic discoveries.

Extracellular matrix protein 1 (ECM1) has angiogenic properties and is expressed by breast tumor cells

Tumor growth and metastasis are critically dependent on the formation of new blood vessels. The present study found that extracellular matrix protein 1 (ECM1), a newly described secretory glycoprotein, promotes angiogenesis. This was initially suggested by in situ hybridization studies of mouse embryos indicating that the ECM1 message was associated with blood vessels and its expression pattern was similar to that of flk-1, a recognized marker for endothelium. More direct evidence for the role of ECM1 in angiogenesis was provided by the fact that highly purified recombinant ECM1 stimulated the proliferation of cultured endothelial cells and promoted blood vessel formation in the chorioallantoic membrane of chicken embryos. Immunohistochemical staining with specific antibodies indicated that ECM1 was expressed by the human breast cancer cell lines MDA-435 and LCC15, both of which are highly tumorigenic. In addition, staining of tissue sections from patients with breast cancer revealed that ECM1 was present in a significant proportion of primary and secondary tumors. Collectively, the results of this study suggest that ECM1 possesses angiogenic properties that may promote tumor progression.

Recombinant human extracellular matrix protein 1 inhibits alkaline phosphatase activity and mineralization of mouse embryonic metatarsals in vitro

Two mRNAs are transcribed from the extracellular matrix protein 1 gene (Ecm1): Ecm1a and an alternatively spliced Ecm1b. We studied Ecm1 mRNA expression and localization during endochondral bone formation and investigated the effect of recombinant human (rh) Ecm1a protein on organ cultures of embryonic mouse metatarsals. Of the two transcripts, Ecm1a mRNA was predominantly expressed in fetal metacarpals from day 16 to 19 after gestation. Ecm1 expression was not found in 16- and 17-day-old metatarsals of which the perichondrium was removed. In situ hybridization and immunohistochemistry demonstrated Ecm1 expression in the connective tissues surrounding the developing bones, but not in the cartilage. Biological effects of rhEcm1a protein on fetal metatarsal cultures were biphasic: at low concentrations, Ecm1a stimulated alkaline phosphatase activity and had no effect on mineralization, whereas at higher concentrations, Ecm1a dose dependently inhibited alkaline phosphatase activity and mineralization. These results suggest that Ecm1a acts as a novel negative regulator of endochondral bone formation.