Modeling autosomal recessive cutis laxa type 1C in mice reveals distinct functions for Ltbp-4 isoforms.

Recent studies have revealed an important role for LTBP-4 in elastogenesis. Its mutational inactivation in humans causes autosomal recessive cutis laxa type 1C (ARCL1C), which is a severe disorder caused by defects of the elastic fiber network. Although the human gene involved in ARCL1C has been discovered based on similar elastic fiber abnormalities exhibited by mice lacking the short Ltbp-4 isoform (Ltbp4S(-/-)), the murine phenotype does not replicate ARCL1C. We therefore inactivated both Ltbp-4 isoforms in the mouse germline to model ARCL1C. Comparative analysis of Ltbp4S(-/-) and Ltbp4-null (Ltbp4(-/-)) mice identified Ltbp-4L as an important factor for elastogenesis and postnatal survival, and showed that it has distinct tissue expression patterns and specific molecular functions. We identified fibulin-4 as a previously unknown interaction partner of both Ltbp-4 isoforms and demonstrated that at least Ltbp-4L expression is essential for incorporation of fibulin-4 into the extracellular matrix (ECM). Overall, our results contribute to the current understanding of elastogenesis and provide an animal model of ARCL1C.

Latent transforming growth factor ß-binding protein 4 is downregulated in esophageal cancer via promoter methylation.

Latent transforming growth factor ß-binding protein 4 (LTBP4) is an extracellular matrix molecule that is a member of important connective tissue networks and is needed for the correct folding and the secretion of TGF-ß1. LTBP4 is downregulated in carcinomas of various tissues. Here we show that LTBP4 is also downregulated in adenocarcinomas and squamous cell carcinomas of the esophagus in vitro and in vivo. Re-expression of LTBP4 in esophageal cancer cell lines reduced cell migration ability, whereas cell viability and cell proliferation remained unchanged. Hypermethylation of the promoter regions of the two main human LTBP4 transcriptional forms, LTBP4L and LTBP4S, was found to be involved in LTBP4 silencing. Detailed investigations of the methylation patterns of the promoter regions of LTBP4L and LTBP4S identified GATA1, SP1, E2F4 and SMAD3 as potential transcription factors involved in LTBP4 expression. In in vitro transcription factor activity studies we discovered E2F4 as novel powerful regulator for LTBP4S expression.

Improved burns therapy: liposomes-in-hydrogel delivery system for mupirocin.

Wounds, particularly burns, are prone to colonization of potentially life-threatening bacteria. Local delivery of antimicrobial agents in sufficient quantities and over longer period of time can reduce risk of burn infections. Mupirocin-in-liposomes-in-hydrogels were proposed as advanced delivery system for improved burn therapy. Mupirocin was entrapped in phosphatidylcholine liposomes of various sizes, namely larger (micron size) vesicles entrapping 74% of drug and sonicated vesicles (below 300 nm) entrapping 49% of drug. Liposomes containing mupirocin were incorporated in chitosan hydrogels (10%, w/w). Incorporation of liposomes in hydrogels resulted in prolonged release of liposomally associated mupirocin, as observed in both in vitro and ex vivo studies. The drug release was affected by the vesicle size. Microbiological evaluation of newly developed system confirmed its antimicrobial potential against Staphylococcus aureus and Bacillus subtilis. Bioadhesiveness of the system was compared with the marketed cream containing mupirocin. Our system exhibited superior bioadhesiveness and sustained mupirocin release profiles to marketed product.

Latent transforming growth factor binding protein 4 (LTBP4) is downregulated in mouse and human DCIS and mammary carcinomas.

BACKGROUND: Transforming growth factor beta (TGF-ß) is able to inhibit the proliferation of epithelial cells and is involved in the carcinogenesis of mammary tumors. Three latent transforming growth factor-ß binding proteins (LTBPs) are known to modulate TGF-ß functions. METHODS: The current study analyses the expression profiles of LTBP4, its isoforms LTBP1 and LTBP3, and TGF-ß1, TGF-ß2, TGF-ß3, and SMAD2, SMAD3 and SMAD4 in human and murine (WAP-TNP8) DCIS compared to invasive mammary tumors. Additionally mammary malignant (MCF7, Hs578T, MDA-MB361) and non malignant cell lines (Hs578BsT) were analysed. Microarray, q-PCR, immunoblot, immunohistochemistry and immunofluorescence were used. RESULTS: In comparison to non-malignant tissues (n = 5), LTBP4 was downregulated in all human and mouse DCIS (n = 9) and invasive mammary adenocarcinomas (n = 5) that were investigated. We also found decreased expression of bone morphogenic protein 4 (BMP4) and increased expression of its inhibitor gremlin (GREM1). Treatment of the mammary tumor cell line (Hs578T) with recombinant TGF-ß1 rescued BMP4 and GREM1 expression. CONCLUSION: We conclude that the lack of LTBP4-mediated targeting in malignant mammary tumor tissues may lead to a possible modification of TGF-ß1 and BMP bioavailability and function.