Current Proteomics - Volume 12, Issue 3, 2015

Growth factors are proteins capable of stimulating cell growth, proliferation and differentiation. The Fibroblast Growth Factor (FGF) family is one of the largest growth factor families, comprising of a group of structurally & functionally related family of 22 polypeptide growth factors. FGFs play their physiological roles by binding to the high affinity FGF receptors (FGFRs) expressed on the surface of the target cells. These proteins are the key players in the cell growth, differentiation, migration, morphogenesis, embryonic development, wound healing, tumor growth etc. There are also reports on the involvement of FGFs in certain diseases. However FGFs have also been shown to have immense potential for use in therapeutics. This review is an attempt to provide an insight to the FGFs, their structural and functional aspects, key biological functions along with a brief account of their implication in diseases and therapeutic uses.

Proliferating Cell Nuclear Antigen (PCNA) is a protein known for its function in DNA replication in all eukaryotic cells. PCNA also has a role in DNA repair when exterior factors, like mutagenic UV-B radiation of sunlight, free radicals, ionizing radiations, chemical mutagens, etc., result in damage to DNA either genetoxically or cytotoxically. PCNA is usually of a toroidal shape and is made-up of either homo- or hetero-trimers. PCNA in Arabidopsis thaliana has two subunits; PCNA1 and PCNA2 that forms a homotrimeric structure. We found that the two subunits (PCNA1 and PCNA2) have a 97% similarity in their structures. Many studies have been conducted on PCNA from humans or yeast, but there is very little research done on plant PCNA. This study aims to close that gap, by conducting a study on PCNA subunits in Arabidopsis thaliana by predicting its 3D structure, domain analysis, subcellular localization, docking site prediction and PCNA interactome. Interactome analysis of PCNA revealed that it interacts with many proteins in DNA repair, such as Rad5, RAD9, RFC3, RFC5, RFC1, which are all a part of pathways involved in DNA repair. Interestingly we found that PCNA interacts with AtBRD1which is controlling shoot differentiation and meristem organization.

The developing seed of soybean is susceptible to high temperature and humidity stress in the field, resulting in pre-harvest seed deterioration. Some soybean cultivars are found to be resistant to the deterioration. However, the resistance mechanism is not yet understood at molecular level. To understand the resistance mechanism, the extracted proteins from the developing seed (R7 period) of a resistant soybean cultivar Xiangdou No. 3 under HTH stress were analyzed by two dimensional electrophoresis (2-DE). The abundance of 45 protein spots were found to be significantly changed, and they were further analyzed by MALDI-TOF MS. Based on the majority of these identified proteins, together with the metabolomics and physiological and biochemical data, a potential resistance mechanism was proposed, which involved in G protein-mediated and calcium-dependent signaling pathways, as well as ROS, NO, ethylene, and auxin signaling pathways; to increase resistance, the stressed developing seed enhanced its cell ultrastructure stability, ROS scavenging, photorespiratory rate, ammonium recycling, protein folding and assembly and secondary metabolite biosynthesis, whereas reduced its energy depletion. In addition, combined with our previous comparative proteomics analysis with a pre-harvest seed deterioration sensitive soybean cv. Ningzhen No. 1, the similarities and differences in the HTH stress-responsive metabolic pathways and cellular processes in the developing seeds between the two soybean cultivars were discussed. Preharvest seed deterioration resistant and sensitive soybean cultivars were found to adopt some different metabolic pathways and cellular processes to response to HTH stress. Xiangdou No. 3 possessed more stable cell ultrastructure, lower energy depletion, more enhanced protein folding and assembly and higher protein and oil concentration in its developing seed under HTH stress. All these differences might be the major reasons why Xiangdou No. 3 is more resistant to pre-harvest seed deterioration than Ningzhen No. 1. Such a result allows us to further understand how soybean developing seed responds to HTH stress at protein level and help us in breeding of resistant soybean cultivars.

Protein capsules are gaining much importance in pharmaceutical industry due to their use in drug delivery. This study presents a novel method of preparing capsules from Bovine Serum Albumin (BSA) and the role of pH in their size distribution. SEM analysis shows that capsules of 3 to 15 μm sizes are formed. Circular dichroic studies of these capsules show that the conformation of these capsules is intact. Contact angle measurements and surface tension studies show that adsorption of these capsules to solid surfaces is observed near pI is favored. This study will be useful in designing pH stimulated protein capsules for release of drugs.

In order to examine underlying mechanisms of the impressive regeneration in Dendrorhynchus Zhejiangensis, a two-dimensional gel electrophoresis (2-DE) combined with mass spectrometric analysis was employed. 70 proteins involved in regenerative process were identified and 33 proteins were up-regulated and others were down-regulated in fracture injured model. Among them, about 79% were cell cytoskeleton proteins and motor proteins. As the representatives, the expression profiles of Actin and Gelsolin-like protein (GSN), both of which were involved in cell motility, in response to body breakage of nemerteans were examined. Two genes showed similar expression patterns during regeneration process and both of them were first constantly up-regulated at 1h and 3h after being broken, then down-regulated to a lower level at 3rd day. The results suggested that Actin and GSN play important roles in regeneration of D. Zhejiangensis.

The effect of alkanes, viz. n-hexane, n-heptane and n-octane on the extracellular proteome and secretome of a solvent tolerant Pseudomonas aeruginosa has been described. Superoxide dismutase, GroEL, A-type flagellin and the porin OprF were altered significantly. The presence of these proteins in the extracellular proteome of solvent-grown cells indicates their role in the cellular adaptation of the strain to a high alkane environment. Up regulation of superoxide dismutase indicates creation of oxidative stress for the bacterial cell in an alkane-rich environment. This secretome analysis is useful for gaining a better understanding of the solvent mediated oxidative stress and the role of superoxide dismutase and GroEL expression as possible markers of solvent tolerance.