Pathogenic Potential of Hic1-Expressing Cardiac Stromal Progenitors

The cardiac stroma contains multipotent mesenchymal progenitors. However, lineage relationships within cardiac stromal cells are poorly defined. Here, we identified heart-resident PDGFRa(+) SCA-1(+) cells as cardiac fibro/adipogenic progenitors (cFAPs) and show that they respond to ischemic damage by generating fibrogenic cells. Pharmacological blockade of this differentiation step with an anti-fibrotic tyrosine kinase inhibitor decreases post-myocardial infarction (post-MI) remodeling and leads to improvement in cardiac function. In the undamaged heart, activation of cFAPs through lineage-specific deletion of the gene encoding the quiescence-associated factor HIC1 reveals additional pathogenic potential, causing fibrofatty infiltration within the myocardium and driving major pathological features pathognomonic in arrhythmogenic cardiomyopathy (AC). In this regard, cFAPs contribute to multiple pathogenic cell types within cardiac tissue and therapeutic strategies aimed at modifying their activity are expected to have tremendous benefit for the treatment of diverse cardiac diseases

The many facets of the matricelluar protein periostin during cardiac development, remodeling, and pathophysiology

Periostin is a member of a growing family of matricellular proteins, defined by their ability to interact with components of the extracellular milieu, and with receptors at the cell surface. Through these interactions, periostin has been shown to play a crucial role as a profibrogenic molecule during tissue morphogenesis. Tissues destined to become fibrous structures are dependent on cooperative interactions between periostin and its binding partners, whereas in its absence, these structures either totally or partially fail to become mature fibrous entities. Within the heart, fibrogenic differentiation is required for normal tissue maturation, remodeling and function, as well as in response to a pathological myocardial insult. In this review, aspects related to the function of periostin during cardiac morphogenesis, remodeling and pathology are summarized

Nanofiltration of hormone mimicking trace organic contaminants

The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF) membranes have been examined. Two NF membranes having different pore size were used in laboratory-scale nanofiltration experiments with feed solutions spiked with a hormone mimicking compound ¾ nonylphenol, tert-butyl phenol, or bisphenol A. Retention of the compounds was determined at various solution chemistries, namely aqueous solution pH, ionic strength, and presence of natural organic matter. The nanofiltration behavior of the selected hormone mimicking compounds appears similar to that of natural hormones as reported in our previous work. While the solution pH can dramatically influence the retention of hormone mimicking compounds by a loose NF membrane, ionic strength does not affect the nanofiltration of such contaminants. However, in the presence of natural organic matter in the feed solution, ionic strength appears to play a significant role in solute-solute and solute-membrane interactions, resulting in increased retention due to partitioning of the hormone mimicking compounds onto organic matter at a higher ionic strength

Biodistribution Studies of Polymeric Nanoparticles for Drug Delivery in Mice.

Duchenne muscular dystrophy (DMD) is a severe hereditary neuromuscular disorder caused by mutations in the dystrophin gene. Antisense-mediated targeted exon skipping has been shown to restore dystrophin expression both in DMD patients and in the mdx mouse, the murine model of DMD, but the ineffective delivery of these molecules limits their therapeutic use. We demonstrated that PMMA/N-isopropil-acrylamide (ZM2) nanoparticles (NPs), administered both intraperitoneally and orally, were able to deliver 2′OMePS antisense inducing various extents of dystrophin restoration in the mdx mice. Defining NP biodistribution is crucial to improve effects on target and dose regimens; thus, we performed in vivo studies of novel ZM4 NPs. ZM4 are conjugated with NIR fluorophores as optical probes suitable for studies on the Odyssey Imaging System. Our results indicate that NPs are widely distributed in all body muscles, including skeletal muscles and heart, suggesting that these vehicles are appropriate to deliver antisense oligonucleotides for targeting striated muscles in the DMD animal model, thus opening new horizons for Duchenne therapy

An enhancer required for transcription of the Col6a1 gene in muscle connective tissue is induced by signals released from muscle cells.

Collagen VI is a survival factor for skeletal muscle produced by endomysial cells and localized in connective tissue around muscle fibers. Mutations of its genes (COL6A1, COL6A2 and COL6A3) cause two muscular disorders, Bethlem myopathy and Ullrich disease. Expression of Collagen VI is highly dynamic during development, suggesting that developmental and homeostatic cues of the muscle microenvironment are relevant to confine its expression in this tissue. In face of the large body of work highlighting the relevance for human diseases of the adhesion of muscle cells with their surrounding extracellular matrix, remarkably little is known on how myogenic cells control gene expression in the connective tissue cells that produce such matrix. By expressing promoter-lacZ constructs in transgenic mice, we identify a Col6a1 gene enhancer region that is necessary for activation of transcription in connective tissue cells associated with skeletal muscle. By means of a lacZ transgenic mouse line crossed in metD/D mutant background, in which muscles of limb buds fail to form, we provide evidence that the presence of cells of the myogenic lineage is needed for enhancer activation in mesenchymal cells. Accordingly, lack of myogenic cells in limb buds of metD/D mice reduces Collagen VI deposition in connective tissue. The Col6a1 enhancer characterized here is conserved in mammals and may be relevant in some cases of heritable diseases of Collagen VI

Analysis of regulatory regions of Emilin1 gene and their combinatorial contribution to tissue-specific transcription

The location of regions that regulate transcription of the murine Emilin1 gene was investigated in a DNA fragment of 16.8 kb, including the entire gene and about 8.7 and 0.6 kb of 5'- and 3'-flanking sequences, respectively. The 8.7-kb segment contains the 5'-end of the putative 2310015E02Rik gene and the sequence that separates it from Emilin1, whereas the 0.6-kb fragment covers the region between Emilin1 and Ketohexokinase genes. Sequence comparison between species identified several conserved regions in the 5'-flanking sequence. Most of them contained chromatin DNase I-hypersensitive sites, which were located at about -950 (HS1), -3100 (HS2), -4750 (HS3), and -5150 (HS4) in cells expressing Emilin1 mRNA. Emilin1 transcription initiates at multiple sites, the major of which correspond to two Initiator sequences. Promoter assays suggest that core promoter activity was mainly dependent on Initiator1 and on Sp1-binding sites close to the Initiators. Moreover, one important regulatory region was contained between -1 and -169 bp and a second one between -630 bp and -1.1 kb. The latter harbors a putative binding site for transcription factor AP1 matching the location of HS1. The function of different regions was studied by expressing lacZ constructs in transgenic mice. The results show that the 16.8-kb segment contains regulatory sequences driving high level transcription in all the tissues where Emilin1 is expressed. Moreover, the data suggest that transcription in different tissues is achieved through combinatorial cooperation between various regions, rather than being dependent on a single cis-activating region specific for each tissue

Overlapping, complementary and site-specific expression pattern of genes of the EMILIN/Multimerin family

The EDEN gene superfamily comprises genes that contain the EMI domain, a structural motif recently identified in proteins of the extracellular matrix. We report here the detailed expression pattern of genes of the EMILIN/Multimerin family, the most numerous group of EDEN superfamily, during mouse development. In situ hybridization has revealed that the EMILIN/Multimerin genes are particularly expressed in the cardio-vascular system and in mesenchymal cells. In general, the territories of expression of each gene are partially overlapping or complementary with that of other members of the family and, usually, more than one gene of the family is active in different tissues, consistent with the possibility of functional compensation. The analysis is particularly relevant in the interpretation of gene targeting experiments