A synthetic nonapeptide derived from the sequence of a platelet type I collagen receptor inhibits type I collagen-mediated platelet aggregation

Natural healing-inspired collagen-targeting surgical protein glue for accelerated scarless skin regeneration

Skin scarring after deep dermal injuries is a major clinical problem due to the current therapies limited to established scars with poor understanding of healing mechanisms. From investigation of aberrations within the extracellular matrix involved in pathophysiologic scarring, it was revealed that one of the main factors responsible for impaired healing is abnormal collagen reorganization. Here, inspired by the fundamental roles of decorin, a collagen-targeting proteoglycan, in collagen remodeling, we created a scar-preventive collagen-targeting glue consisting of a newly designed collagen-binding mussel adhesive protein and a specific glycosaminoglycan. The collagen-targeting glue specifically bound to type I collagen in a dose-dependent manner and regulated the rate and the degree of fibrillogenesis. In a rat skin excisional model, the collagen-targeting glue successfully accelerated initial wound regeneration as defined by effective reepithelialization, neovascularization, and rapid collagen synthesis. Moreover, the improved dermal collagen architecture was demonstrated by uniform size of collagen fibrils, their regular packing, and a restoration of healthy tissue component. Collectively, our natural healing-inspired collagen-targeting glue may be a promising therapeutic option for improving the healing rate with high-quality and effective scar inhibition.

Targeting collagen for diagnostic imaging and therapeutic delivery

As the most abundant protein in mammals and a major structural component in extracellular matrix, collagen holds a pivotal role in tissue development and maintaining the homeostasis of our body. Persistent disruption to the balance between collagen production and degradation can cause a variety of diseases, some of which can be fatal. Collagen remodeling can lead to either an overproduction of collagen which can cause excessive collagen accumulation in organs, common to fibrosis, or uncontrolled degradation of collagen seen in degenerative diseases such as arthritis. Therefore, the ability to monitor the state of collagen is crucial for determining the presence and progression of numerous diseases. This review discusses the implications of collagen remodeling and its detection methods with specific focus on targeting native collagens as well as denatured collagens. It aims to help researchers understand the pathobiology of collagen-related diseases and create novel collagen targeting therapeutics and imaging modalities for biomedical applications.

The signal transduction pathway of the nonintegrin receptor of 65 kDa is different from glycoprotein VI

The identity and signal pathways of a platelet nonintegrin receptor for type I collagen, 65 kDa, are not established. In this investigation, we have examined whether there is a difference in the signal transduction pathways between the 65-kDa protein and glycoprotein VI (GP VI). Results from this study show that these two proteins are different based on the following facts. First, the anti-65-kDa antibody does not precipitate GP VI and vice versa. Second, the Fc receptor (FcR) gamma chain which associates with GP VI after exposure to collagen does not associate with the 65-kDa protein. Third, tyrosine phosphorylation of the FcR gamma chain was obtained by Fab fragments of anti-GP VI but not by anti-65 kDa. These results suggest that the signal transduction pathway of the platelet receptors for the 65-kDa protein and GP VI are different.

Mechanisms of platelet aggregation

Platelet aggregation is initiated by receptor activation coupled to intracellular signaling leading to activation of integrin alphaIIbbeta3. Recent advances in the study of platelet receptors for collagen, von Willebrand factor, thrombin, and adenosine diphosphate are providing new insights into the mechanisms of platelet aggregation.

Role of Nitric Oxide Synthase in Collagen–Platelet Interaction: Involvement of Platelet Nonintegrin Collagen Receptor Nitrotyrosylation

Platelets possess the endothelial isoform of nitric oxide synthase (eNOS), which plays an important role in platelet function. Other laboratories, including ours, have reported that nitric oxide (NO) is released upon exposure of platelets to collagen, but the mechanism of the interaction is not yet established. The objective of this study is to examine the possible role of nonintegrin receptor nitrotyrosylation on collagen-induced platelet aggregation. Results of the study show that two platelet proteins with M(r) of 65- and 23-kDa proteins are nitrotyrosylated in a time-dependent manner after the addition of type I collagen. The M(r) 65-kDa protein is identified as the platelet receptor for type I collagen. The recombinant protein of the platelet receptor for type I collagen can also be nitrotyrosylated. The nitrotyrosylated recombinant protein loses its ability to inhibit type I collagen-induced platelet aggregation. In addition, the polyclonal anti-65 kDa immunoprecipitates eNOS suggesting that the platelet nonintegrin receptor for type I collagen is closely linked to the eNOS. These results demonstrate that the inhibitory effect of NO on collagen-induced platelet aggregation may be mediated by the nitrotyrosylation of the 65-kDa receptor.