Understanding fibroblast activation protein (FAP): Substrates,activities, expression and targeting for cancer therapy

Fibroblast activation protein (FAP) is best known for its heightened expression in tumour stroma. This atypical serine protease has both dipeptidyl peptidase and endopeptidase activities, cleaving substrates at a post-proline bond. FAP expression is difficult to detect in non-diseased adult organs, but is greatly upregulated in sites of tissue remodelling, which include liver fibrosis, lung fibrosis, atherosclerosis, arthritis, tumours and embryonic tissues. Due to its restricted expression pattern and dual enzymatic activities, FAP is emerging as a unique therapeutic target. However, methods to exploit and target this protease are advancing more rapidly than knowledge of the fundamental biology of FAP. This review highlights this imbalance, emphasising the need to better define the substrate repertoire and expression patterns of FAP to elucidate its role in biological and pathological processes.     

The impact of collagen on softening of grass carp (Ctenopharyngodon idella) fillets stored under superchilled and ice storage

The objective of this work was to study the impact of collagen on softening of grass carp (Ctenopharyngodon idella) fillets during chilled storage. The fillets were stored under superchilling (?1.5 ± 0.2 °C) and with ice (0.2 ± 0.1 °C) for 21 days, and texture properties, collagen and the related enzyme activities were measured. Results showed that firmness and collagen content were strongly influenced by storage temperature and time. Fillet firmness decreased by 32.3% (superchilling) and 49.6% (ice stored) of the initial values after 3 days of storage, respectively. Total collagen content decreased with time, but different collagen fractions showed variations. Collagen degraded to different extents depending on storage conditions as indicated by SDS‐PAGE and amino acid analysis. In addition, collagenase activity declined significantly during the first 3 days, followed by a slow increase. This study demonstrated that collagen degradation was involved in grass carp fillet softening and provided useful information for fillet quality improvement.     

Meat quality of kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus): Carcass yield, physical quality and chemical composition of kudu and impala Longissimus dorsi muscle as affected by gender and age

The meat quality of kudu and impala was compared. Live weight and carcass weight differed between species, genders and age groups. Impala had the highest dressing percentage while kudu had the highest live weight and carcass weight. Kudu had the lowest fat content while female animals had a higher fat and myoglobin content than males. Sub-adults had a higher ash content than adults. Species, gender and age had no effect of pH, drip loss, cooking loss or tenderness although kudu had higher L*, a*, b* and chroma values than impala. Impala sub-adults had significantly higher insoluble collagen, soluble collagen, total collagen and hydroxyproline content than kudu sub-adults. Kudu had the highest potassium levels while impala had the highest phosphorus levels. Potassium, sodium, iron and copper levels also differed between species.     

Isolation and characterisation of acid-solubilised collagen from the skin of Nile tilapia (Oreochromis niloticus)

Acid-solubilised collagen (ASC) was extracted from the skin of Nile tilapia (Oreochromis niloticus) and characterisation was studied. The results indicated that the yield of ASC was 39.4% on the basis of dry weight. This ASC was rich in glycine (35.6%). The amount of imino acids, proline and hydroxyproline, in ASC was 210 residues per 1000 residues. The ultraviolet (UV) absorption spectrum of ASC showed that the distinct absorption was at 220 nm. ASC showed transition curve at maximum temperature (T_max) of 32.0 °C in 0.05 M acetic acid, about 12 °C lower than that of calf skin collagen. Maximum solubility (0.75 mg/ml) in 0.5 M acetic acid was observed at pH 3. Solubility reached the minimum at pH 7. A sharp decrease in solubility was observed in 2% (w/v) NaCl or above. Biochemical studies indicated that ASC was composed of the α1α2α3 heterotrimers.     

热水提取罗非鱼鱼鳞胶原蛋白的研究

本文对热水法提取罗非鱼鳞胶原蛋白的条件进行了优化,并测定了鱼鳞胶原蛋白的氨基酸组成.结果发现,罗非鱼鳞胶原蛋白的最佳提取工艺为提取温度100℃,pH值6.0,液固比12,时间2h,此时蛋白得率为265.3mg/g原料.氨基酸检测结果发现,所提取鱼鳞蛋白含17种氨基酸,其中7种必须氨基酸,胶原蛋白的特征氨基酸羟脯氨酸含量达10.4g/100g原料.     

Development of annulus fibrosus tissue construct with hydrogel coils containing pre-conditioned mesenchymal stem cell

Low back pain associated with degenerative disc diseases has been a major health concern that brings suffering to the patients physically and economically.Many existing therapeutic strategies provide shortterm relief of symptoms rather than treatment of the underlying cause.Development of an engineered tissue for disc regeneration is still in its infancy due to the limited autologous healthy disc cell source from the patients.It is also challenging to mimic the complexity of micro-architecture in the native disc tissue that determine their unique structural properties.To date,simple tissue models that mimic the annulus fibrosus(AF)micro-environment for understanding the potential of mesenchymal stem cells(MSCs)in AF tissue engineering are still lacking.In this study,the assembly of a coiled hydrogel microfiber has shown its capability to encapsulate MSCs and create an engineered tissue model that mimics the multiple lamellae of native AF.Using this model,we investigated the potential of MSCs that were previously induced by ascorbic acid(AA).Compared to non-induced MSCs,AA-induced MSCs exhibited significant increase in AF-associated biomarkers during later development in the engineered AF tissue model and also encouraged collagen accumulation through the down-regulated catabolic gene MMP1 and upregulated anti-catabolic gene TIMP1.Furthermore,AA-induced MSCs exhibited a Col2/Col1 ratio closer to that of a native AF tissue.These results suggested that AA-induced MSCs could be a potential cell source for AF tissue engineering and this established tissue model may provide a simple tool for successful AF tissue engineering strategies in the future.     

对蛋壳膜中角蛋白与胶原蛋白的提取分离技术及功能多肽的概述

中国是世界第一禽蛋生产和消费大国。随着人们对鸡蛋消费量的增加以及鸡蛋的集中加工使得大量蛋壳堆积与丢弃,这不仅对环境造成了严重的污染,也是资源上的极度浪费,对蛋壳的资源化利用具有极其重要的意义。国内外对蛋壳的资源化利用甚多,而对蛋壳膜的利用则相对较少。事实上,蛋壳膜是蛋白和多肽等的潜在资源,具有十分可观的应用价值。为此本文概述了蛋壳膜这一具有高附加值的生物膜,并对其内在的角蛋白与胶原蛋白及其生物活性肽进行了相应的介绍,着重强调了其提取分离的方法。旨在为开发利用鸡蛋壳膜这一丰富的资源提供科学的理论依据。     

Exploration of collagen recovered from animal by-products as a precursor of bioactive peptides: Successes and challenges

A large amount of food-grade animal by-products is annually produced during industrial processing and they are normally utilized as animal feed or other low-value purposes. These by-products are good sources of valuable proteins, including collagen or gelatin. The revalorization of collagen may lead to development of a high benefit-to-cost ratio. In this review, the major approaches for generation of collagen peptides with a wide variety of bioactivities were summarized, including antihypertensive, antioxidant and antidiabetic activities, and beneficial effects on bone, joint and skin health. The biological potentials of collagen peptides and their bioavailability were reviewed. Moreover, the unique advantages of collagen peptides over other therapeutic peptides were highlighted. In addition, the current challenges for development of collagen peptides as functional food ingredients were also discussed. This article discusses the opportunity to utilize collagen peptides as high value-added bio-functional ingredients in the food industry.     

Effect of muscular hypertrophy on physico-chemical, biochemical and texture traits of meat from yearling bulls

The effect of the presence of the double-muscling gene either homozygous (mh/mh) or heterozygous (mh/+) on the physico-chemical, biochemical and texture traits of Longissimus thoracis muscle of yearling bulls of the Asturiana de los Valles (AV) breed was studied. Meat of mh/mh bulls had lower amount of intramuscular fat (p<0.001) and also lower total (p<0.01) and insoluble collagen (p<0.05), although the double-muscling genotype did not affect collagen solubility. Homozygous animals had lower pigment content (p<0.05) and a lighter meat, showing lower water holding capacity, estimated as expressible juice under pressure (p<0.001). Genotype affected significantly the metabolic traits of muscle, with mh/mh animals having higher muscle glycolytic metabolism, assessed by a higher (p<0.001) lactate dehydrogenase (LDH) activity and lower (p<0.001) oxidative activity of the isocitrate dehydrogenase (ICDH). The percentage of myosin heavy chain I in muscle was lower, although not significantly, for mh/mh bulls compared to mh/+ bulls. Texture measurements performed on raw material showed that meat of mh/mh bulls had lower resistance to total and 80% compression, which means lower background or collagen toughness. However, there were no differences between genotypes on shear force of cooked meat. Therefore, the physico-chemical, biochemical and texture traits of meat from mh/mh and mh/+ bull are in general significantly different, which could affect the sensorial quality of meat and hence the consumer acceptance.     

Evaluation of sericin/collagen membranes as prospective wound dressing biomaterial

Sericin, a silk protein, has high potential for use in biomedical applications. In this study, wound dressing membranes of Sericin (S) and Collagen (C) were prepared by glutaraldehyde cross-linking at S/C; 2:1, 1:1, 1:2, and 0:1 weight ratios. They were stable in water for 4 weeks. However, increasing the proportion of sericin had decreasing effect on the membrane stability. Water swelling property of membranes was enhanced with sericin. The highest water swelling was obtained in 1:1 group (9.06 g/g), but increasing collagen or sericin content in the membranes had a diminishing effect. Highest water vapor transmission rate was obtained with 1:2 group (1013.80 g/m²/day). Oxygen permeability results showed that 1:2 (7.67 mg/L) and 2:1 (7.85 mg/L) S/C groups were better than the other groups. While sericin decreased the tensile strength and elongation of membranes, it increased modulus. Sericin also increased brittleness of membranes, but their UTS range (24.93–44.92 MPa) was still suitable for a wound dressing. Membranes were not penetrable to microorganisms. Cytotoxicity studies showed that fibroblasts and keratinocytes attached and gained their characteristic morphologies. They also proliferated on membranes significantly. After 1 week of subcutaneous implantation, a fibrous capsule formed around all membranes with an acute inflammation. Sericin containing membranes showed signs of degradation (at 2nd week), while collagen only membranes remained largely intact. Eventually, sericin containing membranes degraded in 3 weeks with moderate inflammatory response. Overall results suggest that sericin/collagen membranes would be favorable as wound dressing material when sericin ratio is less than or equal to the collagen component.