Homozygosity for a missense mutation in SERPINH1, which encodes the collagen chaperone protein HSP47, results in severe recessive osteogenesis imperfecta.
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The collagen V homotrimer [alpha1(V)](3) production is unexpectedly favored over the heterotrimer [alpha1(V)](2)alpha2(V) in recombinant expression systems.
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Effect of HSP47 expression levels on heterotrimer formation among type IV collagen alpha3, alpha4 and alpha5 chains.
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We previously established stable transformants of the human embryonic kidney 293 (HEK293) cell line that express type IV collagen alpha3, alpha4 and wild-type or mutant-type alpha5 chains. Using these cell lines, we confirmed that these three chains form a heterotrimer and that alpha5 chains containing mutations seen in Alport syndrome are defective in heterotrimerization. In these studies, the amount of heterotrimer that formed was much less than expected relative to the amount of alpha(IV) chains expressed. The aim of the present study was to determine the effect of the collagen-specific molecular chaperone heat shock protein 47 (HSP47), whose expression is low in HEK293 cells, on the heterotrimerization of alpha3(IV), alpha4(IV) and alpha5(IV) chains. Reduction of HSP47 levels by siRNA resulted in defects of heterotrimerization among the three chains, indicating that HSP47 plays a critical role in the heterotrimerization. On the other hand, overexpression of HSP47 did not influence heterotrimerization. Since many enzymes and molecular chaperons assist correct folding and trimerization of collagens, one or more enzymes and/or molecular chaperones, other than HSP47, might be deficient in HEK293 cells. Overexpression of HSP47 decreased the secretion of heterotrimers containing the mutant alpha5(IV) chain, suggesting that HSP47 overexpression might enhance the quality control mechanisms of collagen synthesis by inhibiting the secretion of incorrectly structured heterotrimers. (+info)
Immunolocalization of heat shock proteins 27 and 47 during repair of induced oral ulcers.
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Heat shock proteins (Hsps) 27 and 47 are involved in the control of apoptosis, cell migration, and collagen synthesis. There is some understanding of the immunolocalization of these proteins during the repair process in skin and gastrointestinal mucosa, but their expressions in normal and injured oral mucosa are unknown. The aim of this study was to analyze the immunolocalization and intensity of these proteins in oral ulcers induced in rats and to compare these expression levels with those reported in skin and gastric mucosa. Ulcers were induced on the ventral surface of the tongues of rats. The rats were then euthanized at 0, 24, 48, 72, and 120 h. Hsp27 expression remained low in the first hours of repair, but was higher at 72 h, mainly in the migrating epithelium. Expression of Hsp47 was high at 48 h, mainly in fibroblasts, cells of the vascular wall, and basal keratinocytes of migrating epithelium. In the control group, expressions of these proteins were low, which indicates that these Hsps are constitutive proteins in oral mucosa. Expression levels were similar to those reported in the healing of skin lesions and gastric ulcer, suggesting a common mechanism of Hsp activation in the repair of these tissues. (+info)
CC chemokine receptor 5 deletion impairs macrophage activation and induces adverse remodeling following myocardial infarction.
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