Abstract:Production of insoluble elastin, the major component of elastic fibers, can be modulated by numerous intrinsic and exogenous factors. Because patients with hemolytic disorders characterized with fluctuations in iron concentration demonstrate defective elastic fibers, we speculated that iron might also modulate elastogenesis. In the present report we demonstrate that treatment of cultured human skin fibroblasts with low concentration of iron 2-20 M (ferric ammonium citrate) induced a significant increase in the… Show more
“…2 elastic fibers both at the transcriptional and protein synthesis levels. 40 Even if the effect of iron on elastic fibers might contribute to the elastopathy of -thalassemia, it can hardly explain the complete clinical and structural similarities of the symptoms with inherited PXE. In fact, in hereditary hemochromatosis, whether in human patients or a mouse model, no ectopic calcification of the connective tissue has been reported.…”
-Thalassemia and pseudoxanthoma elasticum (PXE) are distinct genetic disorders. Yet, a dystrophic mineralization phenotype similar to PXE has frequently been associated with -thalassemia or sickle cell anemia patients of Mediterranean descent. These calcifications are clinically and structurally identical to inherited PXE. As we previously excluded the presence of PXE-causing mutations in the ABCC6 gene of -thalassemia patients with PXE manifestations, we hypothesized that a molecular mechanism independent of gene mutations either altered the ABCC6 gene expression or disrupted the biologic properties of its product in the liver or kidneys, which are the tissues with the highest levels of expression. To test this possibility, we investigated Abcc6 synthesis in the liver and kidneys of a -thalassemia mouse model (Hbb th3/؉ ). We found a progressive liver-specific down-regulation of the Abcc6 gene expression and protein levels by quantitative PCR, Western blotting, and immunofluorescence. The levels of Abcc6 protein decreased significantly at 6 months of age and stabilized at 10 months and older ages at ϳ25% of the wild-type protein levels. We studied the transcriptional regulation of the Abcc6 gene in wild-type and Hbb th3/؉ mice, and we identified the erythroid transcription factor NF-E2 as the main cause of the transcriptional down-regulation using transcription factor arrays and chromatin immunoprecipitation. The Hbb th3/؉ mice did not develop spontaneous calcification as seen in the Abcc6 ؊/؊ mice probably because the Abcc6 protein decrease occurred late in life and was probably insufficient to promote mineralization in the Hbb th3/؉ mouse C57BL/6J genetic background. Nevertheless, our result suggested that a similar decrease of ABCC6 expression occurs in the liver of -thalassemia patients and may be responsible for their frequent PXE-like manifestations.
“…2 elastic fibers both at the transcriptional and protein synthesis levels. 40 Even if the effect of iron on elastic fibers might contribute to the elastopathy of -thalassemia, it can hardly explain the complete clinical and structural similarities of the symptoms with inherited PXE. In fact, in hereditary hemochromatosis, whether in human patients or a mouse model, no ectopic calcification of the connective tissue has been reported.…”
-Thalassemia and pseudoxanthoma elasticum (PXE) are distinct genetic disorders. Yet, a dystrophic mineralization phenotype similar to PXE has frequently been associated with -thalassemia or sickle cell anemia patients of Mediterranean descent. These calcifications are clinically and structurally identical to inherited PXE. As we previously excluded the presence of PXE-causing mutations in the ABCC6 gene of -thalassemia patients with PXE manifestations, we hypothesized that a molecular mechanism independent of gene mutations either altered the ABCC6 gene expression or disrupted the biologic properties of its product in the liver or kidneys, which are the tissues with the highest levels of expression. To test this possibility, we investigated Abcc6 synthesis in the liver and kidneys of a -thalassemia mouse model (Hbb th3/؉ ). We found a progressive liver-specific down-regulation of the Abcc6 gene expression and protein levels by quantitative PCR, Western blotting, and immunofluorescence. The levels of Abcc6 protein decreased significantly at 6 months of age and stabilized at 10 months and older ages at ϳ25% of the wild-type protein levels. We studied the transcriptional regulation of the Abcc6 gene in wild-type and Hbb th3/؉ mice, and we identified the erythroid transcription factor NF-E2 as the main cause of the transcriptional down-regulation using transcription factor arrays and chromatin immunoprecipitation. The Hbb th3/؉ mice did not develop spontaneous calcification as seen in the Abcc6 ؊/؊ mice probably because the Abcc6 protein decrease occurred late in life and was probably insufficient to promote mineralization in the Hbb th3/؉ mouse C57BL/6J genetic background. Nevertheless, our result suggested that a similar decrease of ABCC6 expression occurs in the liver of -thalassemia patients and may be responsible for their frequent PXE-like manifestations.
“…The observed lack of mature elastin structures thus constitutes a serious limitation for tissue engineering of functional blood vessels designed for the high-pressure circulation. Biosynthesis and subsequent crosslinking of elastin appears to be one of the most complex and tightly regulated processes during the maturation of blood vessels [49].…”
Nearly 20 years have passed since Weinberg and Bell attempted to make the first tissue-engineered blood vessels. Following this early attempt, vascular tissue engineering has emerged as one of the most promising approaches to fabricate orderly and mechanically competent vascular substitutes. In elastic and muscular arteries, elastin is a critical structural and regulatory matrix protein and plays an important and dominant role by conferring elasticity to the vessel wall. Elastin also regulates vascular smooth muscle cells activity and phenotype. Despite the great promise that tissue-engineered blood vessels have to offer, little research in the last two decades has addressed the importance of elastin incorporation into these vessels. Although cardiovascular tissue engineering has been reviewed in the past, very little attention has been given to elastin. Thus, this review focuses on the recent advances made towards elastogenesis and the challenges we face in the quest for appropriate functional vascular substitutes.
“…Numerous studies have been aimed at reversal of damaged skin (reviewed in Mahoney et al, 2009). We described that a proteolytic digest of elastin and iron (ferric ammonium citrate) (Bunda et al, 2005) can stimulate production of tropoelastin in skin and that polyphenols (tannic acid and ellagic acid; Jimenez et al, 2006) that preferentially bind to elastin protect it from proteolysis. Stimulation of new elastic fibers in the skin has also been reported after topical treatment with 17-b-estradiol (Son et al, 2005).…”
We have shown that the steroid hormone aldosterone, recognized for its action on the kidney and the cardiovascular system, also modulates deposition of extracellular matrix in human skin. We have shown that treatment of primary cultures of normal skin fibroblasts with aldosterone (10 n-1 μM), in addition to stimulation of collagen type I expression, induces elastin gene expression and elastic fiber deposition. We have further shown that the elastogenic effect of aldosterone, which can be enhanced in the presence of mineralocorticoid receptor (MR) antagonists spironolactone and eplerenone, is executed in a MR-independent manner via amplification of IGF-I receptor-mediated signaling. Because aldosterone applied alone stimulates both collagen and elastin deposition in cultures of fibroblasts and in cultures of skin explants derived from dermal stretch marks, we postulate that this steroid should be used in the treatment of damaged skin that loses its volume and elasticity. Moreover, aldosterone applied in conjunction with spironolactone or eplerenone induces matrix remodeling and exclusively enhances elastogenesis in cultures of fibroblasts and explants derived from dermal scars and keloids. We therefore propose that intra-lesional injection of these factors should be considered in therapy for disfiguring dermal lesions and especially in prevention of their recurrence after surgical excision.
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