Molecular cloning and characterization of the mouse Ecm1 gene and its 5' regulatory sequences

Lichen Sclerosus: A Current Landscape of Autoimmune and Genetic Interplay

Lichen sclerosus (LS) is an acquired chronic inflammatory dermatosis predominantly affecting the anogenital area with recalcitrant itching and soreness. Progressive or persistent LS may cause urinary and sexual disturbances and an increased risk of local skin malignancy with a prevalence of up to 11%. Investigations on lipoid proteinosis, an autosomal recessive genodermatosis caused by loss-of-function mutations in the extracellular matrix protein 1 (ECM1) gene, led to the discovery of a humoral autoimmune response to the identical molecule in LS, providing evidence for an autoimmune and genetic counterpart targeting ECM1. This paper provides an overview of the fundamental importance and current issue of better understanding the immunopathology attributed to ECM1 in LS. Furthermore, we highlight the pleiotropic action of ECM1 in homeostatic and structural maintenance of skin biology as well as in a variety of human disorders possibly associated with impaired or gained ECM1 function, including the inflammatory bowel disease ulcerative colitis, Th2 cell-dependent airway allergies, T-cell and B-cell activation, and the demyelinating central nervous system disease multiple sclerosis, to facilitate sharing the concept as a plausible therapeutic target of this attractive molecule.

ECM1 secreted by HER2-overexpressing breast cancer cells promotes formation of a vascular niche accelerating cancer cell migration and invasion

The tumor microenvironment is increasingly recognized as key player in cancer progression. Investigating heterotypic interactions between cancer cells and their microenvironment is important for understanding how specific cell types support cancer. Forming the vasculature, endothelial cells (ECs) are a prominent cell type in the microenvironment of both normal and neoplastic breast gland. Here, we sought out to analyze epithelial-endothelial cross talk in the breast using isogenic non-tumorigenic vs. tumorigenic breast epithelial cell lines and primary ECs. The cellular model used here consists of D492, a breast epithelial cell line with stem cell properties, and two isogenic D492-derived EMT cell lines, D492M and D492HER2. D492M was generated by endothelial-induced EMT and is non-tumorigenic while D492HER2 is tumorigenic, expressing the ErbB2/HER2 oncogene. To investigate cellular cross talk, we used both conditioned medium (CM) and 2D/3D co-culture systems. Secretome analysis of D492 cell lines was performed using mass spectrometry and candidate knockdown (KD), and overexpression (OE) was done using siRNA and CRISPRi/CRISPRa technology. D492HER2 directly enhances endothelial network formation and activates a molecular axis in ECs promoting D492HER2 migration and invasion, suggesting an endothelial feedback response. Secretome analysis identified extracellular matrix protein 1 (ECM1) as potential angiogenic inducer in D492HER2. Confirming its involvement, KD of ECM1 reduced the ability of D492HER2-CM to increase endothelial network formation and induce the endothelial feedback, while recombinant ECM1 (rECM1) increased both. Interestingly, NOTCH1 and NOTCH3 expression was upregulated in ECs upon treatment with D492HER2-CM or rECM1 but not by CM from D492HER2 with ECM1 KD. Blocking endothelial NOTCH signaling inhibited the increase in network formation and the ability of ECs to promote D492HER2 migration and invasion. In summary, our data demonstrate that cancer-secreted ECM1 induces a NOTCH-mediated endothelial feedback promoting cancer progression by enhancing migration and invasion. Targeting this interaction may provide a novel possibility to improve cancer treatment.

Stromal protein Ecm1 regulates ureteric bud patterning and branching

The interactions between the nephrogenic mesenchyme and the ureteric bud during kidney development are well documented. While recent studies have shed some light on the importance of the stroma during renal development, many of the signals generated in the stroma, the genetic pathways and interaction networks involving the stroma are yet to be identified. Our previous studies demonstrate that retinoids are crucial for branching of the ureteric bud and for patterning of the cortical stroma. In the present study we demonstrate that autocrine retinoic acid (RA) signaling in stromal cells is critical for their survival and patterning, and show that Extracellular matrix 1, Ecm1, a gene that in humans causes irritable bowel syndrome and lipoid proteinosis, is a novel RA-regulated target in the developing kidney, which is secreted from the cortical stromal cells surrounding the cap mesenchyme and ureteric bud. Our studies suggest that Ecm1 is required in the ureteric bud for regulating the distribution of Ret which is normally restricted to the tips, as inhibition of Ecm1 results in an expanded domain of Ret expression and reduced numbers of branches. We propose a model in which retinoid signaling in the stroma activates expression of Ecm1, which in turn down-regulates Ret expression in the ureteric bud cleft, where bifurcation normally occurs and normal branching progresses.

Human Melanoma cells over-express extracellular matrix 1 (ECM1) which is regulated by TFAP2C

Extracellular matrix 1 (ECM1) is over-expressed in multiple epithelial malignancies. However, knowledge regarding the expression of ECM1 in melanomas and the mechanisms of ECM1 regulation is limited. In this study, we found that ECM1 is over-expressed in several melanoma cell lines, when compared to primary melanocytes, and furthermore, that ECM1 expression paralleled that of TFAP2C levels in multiple cell lines. Knockdown of TFAP2C in the A375 cell line with siRNA led to a reduction in ECM1 expression, and upregulation of TFAP2C with adenoviral vectors in the WM793 cell line resulted in ECM1 upregulation. Utilizing 5’ RACE to identify transcription start sites (TSS) and luciferase reporter assays in the ECM1-overexpressing A375 cell line, we identified the minimal promoter region of human ECM1 and demonstrate that an approximately 100bp fragment upstream of the TSS containing a TATA box and binding sites for AP1, SP1 and Ets is sufficient for promoter activity. Chromatin immunoprecipitation and direct sequencing (ChIP-seq) for TFAP2C in the A375 cell line identified an AP2 regulatory region in the promoter of the ECM1 gene. Gelshift assays further confirmed binding of TFAP2C to this site. ECM1 knockdown reduces melanoma cell attachment and is consistent with findings that ECM1 overexpression has been associated with a poor prognosis. Our investigations show an as yet unrecognized role for TFAP2C in melanoma via its regulation of ECM1.

Interaction between cartilage oligomeric matrix protein and extracellular matrix protein 1 mediates endochondral bone growth

In an effort to define the biological functions of COMP, a functional genetic screen was performed. This led to the identification of extracellular matrix protein 1 (ECM1) as a novel COMP-associated partner. COMP directly binds to ECM1 both in vitro and in vivo. The EGF domain of COMP and the C-terminus of ECM1 mediate the interaction between them. COMP and ECM1 colocalize in the growth plates invivo. ECM1 inhibits chondrocyte hypertrophy, matrix mineralization, and endochondral bone formation, and COMP overcomes the inhibition by ECM1. In addition, COMP-mediated neutralization of ECM1 inhibition depends on their interaction, since COMP largely fails to overcome the ECM1 inhibition in the presence of the EGF domain of COMP, which disturbs the association of COMP and ECM1. These findings provide the first evidence linking the association of COMP and ECM1 and the biological significance underlying the interaction between them in regulating endochondral bone growth.

Interaction of extracellular matrix protein 1 with extracellular matrix components: ECM1 is a basement membrane protein of the skin

The extracellular matrix protein 1 (ECM1) is a secreted glycoprotein, which plays an important role in the structural and functional biology of the skin as demonstrated by the identification of loss-of-function mutations in ECM1 as cause of the genodermatosis lipoid proteinosis, characterized by reduplication of the skin basement membrane and hyalinization of the underlying dermis. To search for binding partner(s) of ECM1, we tested the in vitro binding activity of ECM1a, a major isoform of four ECM1 splice variants, to different skin extracellular matrix proteins (such as laminin 332, collagen type IV, and fibronectin) and polysaccharides (such as hyaluronan, heparin, and chondroitin sulfate A) with solid-phase binding assay. We demonstrated that ECM1a utilizes different regions to bind to a variety of extracellular matrix components. Ultrastructurally, ECM1 is a basement membrane protein in human skin and is part of network-like suprastructures containing perlecan, collagen type IV, and laminin 332 as constituents. Furthermore, ECM1a enhanced the binding of collagen IV to laminin 332 dose-dependently, showing its involvement in the dermal-epidermal junction and interstitial dermis and making the functional link to the pathophysiology of lipoid proteinosis. To our knowledge, this is previously unreported.

Expression of extracellular matrix protein 1 (ECM1) in human skin is decreased by age and increased upon ultraviolet exposure

BACKGROUND

The extracellular matrix protein 1 (ECM1) is expressed in human skin and plays an important role in its normal structure and function. In the rare genetic skin disease lipoid proteinosis, which is characterized by a loss-of-function mutation in the ECM1 gene, skin areas habitually exposed to the sun may show a more severely scarred and photoaged appearance. However, no data are available on the possible involvement of ECM1 expression in intrinsic and extrinsic skin ageing.

OBJECTIVES

We hypothesized that ECM1 expression in human skin is regulated by age- and ultraviolet (UV)-dependent mechanisms.

METHODS

Skin biopsies from 12 patients with histologically confirmed solar elastosis, from non-UV-exposed sites of 12 age-matched controls and 12 young subjects were analysed. To evaluate the influence of acute UV exposure, buttock skin of 10 healthy subjects was irradiated repetitively on 10 days with a solar simulator and compared intraindividually with non-UV-treated contralateral sites. The expression of ECM1 was investigated by immunohistochemistry using an ECM1 antibody detecting ECM1a and ECM1c isoforms. Semiquantitative analysis of staining intensity was carried out by densitometric image analysis.

RESULTS

In normal human skin ECM1a and ECM1c are expressed mainly in the basal cell layers of epidermal keratinocytes and in dermal vessels. For the first time, an expression in the outer root sheath of hair follicles, in sebaceous lobules and epithelium of sweat glands is described. Intrinsically (UV-protected) aged skin shows a significantly reduced expression in basal and upper epidermal cell layers compared with young skin. In photoaged skin, expression is significantly increased within the lower and upper epidermis compared with age-matched UV-protected sites. Importantly, after acute UV exposure in young healthy subjects expression of ECM1 is markedly increased in both lower and upper epidermal cell layers.

CONCLUSIONS

This is the first study to demonstrate a regulation of ECM1 expression in human skin by age and UV exposure. These data suggest that ECM1 expression may represent a cutaneous stress response to acute and chronic UV irradiation.

Suppression of AP-1 constitutive activity interferes with polyomavirus MT antigen transformation ability

Polyomavirus (Py) encodes a potent oncogene, the middle T antigen (MT), that induces cell transformation by binding to and activating several cytoplasmic proteins which take part in transduction of growth factors-induced mitogenic signal to the nucleus. We have previously reported that the AP-1 transcriptional complex is a target for MT during cell transformation although, its activation was not sufficient for establishment of the transformed phenotype. Here we show that expression of a dominant-negative cJun mutant in MT transformed cell lines inhibits its transformation ability, indicating that constitutive AP-1 activity is necessary for cell transformation mediated by MT. Evidences also suggest that proliferation of MT transformed cells in low serum concentrations and their ability to form colonies in agarose are controlled by distinct mechanisms.

Perlecan protein core interacts with extracellular matrix protein 1 (ECM1), a glycoprotein involved in bone formation and angiogenesis

The goal of this study was to discover novel partners for perlecan, a major heparan sulfate proteoglycan of basement membranes, and to examine new interactions through which perlecan may influence cell behavior. We employed the yeast two-hybrid system and used perlecan domain V as bait to screen a human keratinocyte cDNA library. Among the strongest interacting clones, we isolated a approximately 1.6-kb cDNA insert that encoded extracellular matrix protein 1 (ECM1), a secreted glycoprotein involved in bone formation and angiogenesis. The sequencing of the clone revealed the existence of a novel splice variant that we name ECM1c. The interaction was validated by co-immunoprecipitation studies, using both cell-free systems and mammalian cells, and the specific binding site within each molecule was identified employing various deletion mutants. The C terminus of ECM1 interacted specifically with the epidermal growth factor-like modules flanking the LG2 subdomain of perlecan domain V. Perlecan and ECM1 were also co-expressed by a variety of normal and transformed cells, and immunohistochemical studies showed a partial expression overlap, particularly around dermal blood vessels and adnexal epithelia. ECM1 has been shown to regulate endochondral bone formation, stimulate the proliferation of endothelial cells, and induce angiogenesis. Similarly, perlecan plays an important role in chondrogenesis and skeletal development, as well as harboring pro- and anti-angiogenic activities. Thus, a physiological interaction could also occur in vivo during development and in pathological events, including tissue remodeling and tumor progression.

Hematopoietic cells from CD155-transgenic mice express CD155 and support poliovirus replication ex vivo

Despite identification of the poliovirus (PV) receptor (CD155), mechanisms by which this molecule mediates paralytic disease remain obscure. Unanswered questions include CD155 localization in human tissues, the nature of cells supporting the first round of replication, identity of nonneural replication sites, and route of entry into the CNS. In earlier work, we showed that CD155 is expressed on primary human monocytes and that these cells support low, but statistically significant, levels of PV replication ex vivo without prior culturing. We hypothesize that monocytes support PV replication in vivo and that they contribute to pathogenesis. In the current study, we tested whether CD155-transgenic mouse hematopoietic cells express cell surface CD155 and whether these cells support PV replication. We found that the majority of monocyte/macrophages from peritoneal washes express CD155. In addition, 26-32% of CD155-transgenic bone marrow and spleen cells express CD155 on monocyte/macrophages, T cells and hematopoietic precursor cells. Various tissues supported PV replication without pre-culturing, however, pre-culturing or pre-treatment of mice with thioglycollate increased virus yield. These results are consistent with those from human cells and suggest that the CD155 transgenic mouse model is useful to help understand the role of hematopoietic cells in PV pathogenesis.

Genetic dissection of c-myc apoptotic pathways

All biological functions mediated by the c-myc oncoprotein require an intact transactivation domain (TAD). We compared TAD mutants for their ability to promote apoptosis of 32D myeloid cells in response to interleukin-3 (IL-3) deprivation and exposure to chemotherapeutic drugs, and to activate ornithine decarboxylase, an endogenous c-myc target. Different sub-regions of the TAD were required to mediate each function. cDNA microarrays were then used to identify multiple c-myc-regulated transcripts, some of which were also modulated by IL-3 or cytotoxic drugs, as well as by specific sub-regions of the TAD. Several of the c-myc-regulated transcripts had also been previously identified as targets for IFN-gamma. The functional consequences of their deregulation were manifested by a marked sensitivity of c-myc-overexpressing cells to IFN-gamma-mediated apoptosis. Our results establish that several well-characterized functions of c-myc are separable and correlate with the expression of a novel group of target genes, some of which also mediate the apoptotic action of IFN-gamma.

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

The human extracellular matrix protein 1 (Ecm1) gene is located at chromosome band 1q21 close to the epidermal differentiation complex and is transcribed in two discrete mRNAs: a full length Ecm1a and a shorter, alternatively spliced, Ecm1b transcript, the expression of which is restricted to tonsils and skin. The chromosomal localization and the Ecm1b expression in skin prompted us to investigate the role of Ecm1 in keratinocyte differentiation. In this study, we provide evidence for the existence of a relationship between keratinocyte differentiation and expression of the Ecm1b transcript. Cultures of subconfluent undifferentiated normal human keratinocytes express only Ecm1a. Upon reaching confluence, the cells start to differentiate, as measured by keratin K10 mRNA expression. Concomitantly Ecm1b mRNA expression is induced, although expression of Ecm1a mRNA remains unchanged. In addition, treatment of undifferentiated normal human keratinocyte cells with 12-O-tetradecanoyl-phorbol-13-acetate strongly induces the expression of Ecm1b mRNA. Expression of Ecm1b can also be induced by coculturing normal human keratinocytes with lethally irradiated feeder cells and by a diffusible factor secreted by stromal cells. In adult human skin, Ecm1a mRNA is expressed throughout the epidermis with the strongest expression in the basal and first suprabasal cell layers, whereas expression of Ecm1b mRNA is predominantly found in spinous and granular cell layers. Immunohistochemically, Ecm1a expression is almost completely restricted to the basal cell layer, whereas Ecm1b is detected in the suprabasal layers. These results are strongly suggestive of a role for Ecm1b in terminal keratinocyte differentiation, which is also supported by the localization of the Ecm1 gene at 1q21. Refinement of its genomic localization, however, placed Ecm1 centromeric of the epidermal differentiation complex.