Recent Advances: Transglutaminase in Ocular Health and Pathological Processes

Abstract

propelled further research in this field, and a wide variety of techniques have been employed, including peptides [14], small molecules [15], molecules from bacteria [16] and lead compounds discovered by screening [17]. (Figure 1) summarises the ocular disease states that have been linked to TG.Many abbreviations and synonyms of various types of TG have been used in the literature. For example, TG2 will be used in place of commonly encountered abbreviations such as 'TGc' and 'tTG'. Ocular Surface DiseasesStudies that linked TG to ocular surface diseases such as pterygium [18], allergic conjunctivitis [19], dry eye [20] and cicatricial conjunctivitis [21,22] have been performed, and will be described in the following sections. In the cornea and conjunctiva, TG activity can be detected in the intercellular spaces, along the basement membranes, the cytoplasm of the epithelial cells, the superficial stromal keratocytes, as well as in the walls of the conjunctival stromal vessels [4]. Although TG2 can be found within various ocular cell types, TG1 was identified only in the suprabasal layer of the corneal epithelium. AbstractTransglutaminase (TG) is a diverse class of crosslinking enzymes involved in the regulation of cytokine production, endocytosis, cell adhesion, migration, apoptosis and autophagy. It has been implicated in inflammatory diseases, neurodegenerative processes and cancer. The eye is a specialized organ which subserves the important function of vision and has distinctive physiological and anatomical properties that differ from other body tissues. Understanding of the roles of various TGs in the eye therefore require studies specific to cells and tissues of ocular origin. We review the advances in TG research in ocular diseases, including pterygium, glaucoma, cataract and proliferative vitreoretinopathy. TG1 is a molecule important for keratinisation in many cicatrizing diseases of the ocular surface, including keratoconjunctivitis sicca. TG2, with multiple functions, has been shown to be important in inflammation and cell adhesion in various ocular diseases. The results of TG research in each region of the eye are critically assessed and the implications of these studies in the treatment of ocular diseases are discussed. By modifying wound healing process and influencing the amount of inflammation in animal models of human ocular diseases, TG-related strategies are now a possibility for selected clinical scenarios. For example, the use of retinoic acid for severe dry eye has undergone clinical trials. However, in many other areas, more research in selection of specific targets, time of intervention, specific method of delivery of interventional molecules, and safety of therapy in humans may be necessary. One promising area in the future is the use of a TG strategy to modify conjunctival wound healing to increase success rates after glaucoma surgery.

Biological Feature Selection and Disease Gene Identification using New Stepwise Random Forests

“…Regarding GO 0044343 (canonical Wnt signaling pathway involved in regulation of type B pancreatic cell proliferation), it was investigated that pancreatic cardinoma is associated with the optic nerve (Ring, 1967). For GO 0018262 (isopeptide cross-linking), Tong et al (2011) discussed transglutaminase in ocular health and pathological processes. Transglutaminase (TG) is a big class of intra-and extra-cellular enzymes with 9 members, all of which catalyze the formation of epsilon-(γ-glutamyl) lysine isopeptide linkages between peptide substrates, except for a catalytically inactive member Band 4.1 (Tong et al, 2011).…”

“…For GO 0018262 (isopeptide cross-linking), Tong et al (2011) discussed transglutaminase in ocular health and pathological processes. Transglutaminase (TG) is a big class of intra-and extra-cellular enzymes with 9 members, all of which catalyze the formation of epsilon-(γ-glutamyl) lysine isopeptide linkages between peptide substrates, except for a catalytically inactive member Band 4.1 (Tong et al, 2011).…”