IgG antibodies are large molecules of about 150kilodalton made of four peptide chains. It contains two identical class γ heavy chains of about 50 kDa and two identical light chains of about 25 kDa, thus a tetrameric quaternary structure. The two heavy chains are linked to each other and to a light chain each by disulfide bonds. The resulting tetramer has two identical halves, which together form the Y-like shape. Each end of the fork contains an identicalantigen binding site. The various regions and domains of a typical IgG are depicted in the figure to the left. The Fc regions of IgGs bear a highly conserved N-glycosylation site. The N-glycans attached to this site are predominantly core-fucosylated diantennary structures of the complex type. In addition, small amounts of these N-glycans also bear bisecting GlcNAc and α-2,6-linked sialic acid residues.
The various regions and domains of a typical IgG
There are four IgG subclasses (IgG1, 2, 3, and 4) in humans, named in order of their abundance in serum (IgG1 being the most abundant).
|Name||Percent||Crosses placenta easily||Complement activator||Binds to Fc receptor on phagocytic cells||Half Life|
|IgG1||66%||yes (1.47)*||second-highest||high affinity||21 days|
|IgG2||23%||no (0.8)*||third-highest||extremely low affinity||21 days|
|IgG3||7%||yes (1.17)*||highest||high affinity||7 days|
|IgG4||4%||yes (1.15)*||no||intermediate affinity||21 days|
|* Quota cord/maternity concentrations blood. Based on data from a Japanese study on 228 mothers.|
The pathology of the fibrotic proliferative vitreoretinopathy (PVR) membrane represents an excessive wound healing response characterised by cells' proliferation, migration and secretion of extracellular matrix molecules (ECMs). Retinal pigment epithelial (RPE) cells are a major cellular component of the fibrotic membrane. Endothelin-1 (ET-1) has been reported to be involved in the development of PVR in vivo research. However, little is known about the role of ET-1 in RPE cells in vitro. In the present study, we investigated the role of ET-1 in the proliferation, migration and secretion of ECMs (such as type I collagen and fibronectin) in RPE cells in vitro. Our results illustrated that ET-1 promoted the proliferation, migration and secretion of ECMs through the protein kinase B (Akt) and extracellular signal-regulated kinase (Erk) signaling pathways in RPE cells in vitro. These findings strongly suggested that ET-1 may play a vital role in the development of PVR. - Source :PubMed
Complement activation is implicated in the pathogenesis of age-related macular degeneration (AMD). Apolipoprotein E (ApoE) and complement activation products such as membrane attack complex (MAC) are present in eyes of individuals with AMD. Herein, we investigated the effect of complement activation on induction of ApoE accumulation in human retinal pigment epithelial (RPE) cells. - Source :PubMed
Retinal pigment epithelium (RPE) dysfunction underlies the retinal degenerative process in age-related macular degeneration (AMD), and thus RPE cell replacement provides an optimal treatment target. We characterized longitudinally the efficacy of RPE cells derived under xeno-free conditions from clinical and xeno-free grade human embryonic stem cells (OpRegen) following transplantation into the subretinal space of Royal College of Surgeons (RCS) rats. - Source :PubMed
Semaphorins form a family of secreted and membrane-bound molecules that were identified originally as axonal guidance factors during neuronal development. Given their wide distribution in many including mature tissues, semaphorin 4D (sema4D) and its main functional receptor plexin B1 (plxnB1) are expected to fulfill additional functions that remain to be uncovered. A main characteristic of the plexin receptor family is its ability to reorganize the cytoskeleton. PlxnB1 specifically may directly interact with Rho family GTPases to regulate F-actin driven pathways in cells in culture. Diurnal clearance phagocytosis by the retinal pigment epithelium (RPE) of photoreceptor outer segment fragments (POS) is critical for photoreceptor function and longevity. In this process, rearrangement of RPE cytoskeletal F-actin via activation of the Rho family GTPase Rac1 is essential for POS internalization. Here, we show a novel role in POS phagocytosis by RPE cells in culture and in vivo for plexin B1 and its ligand sema4D. Exogenous sema4D abolishes POS internalization (but not binding) by differentiated RPE cells in culture by decreasing the GTP load of Rac1. In the rat eye, sema4D localizes to retinal photoreceptors, while PlxnB1 is expressed by neighboring RPE cells. At the peak of diurnal retinal phagocytosis after light onset, plxnB1 phosphorylation and sema4D levels are reduced in wild-type rat retina in situ but not in mutant RCS rat retina in which the RPE lacks phagocytic activity. Finally, increased POS phagosome content after light onset is observed in the RPE in situ of mice with either plxnB1 or sema4D gene deletion. Altogether, our results demonstrate a novel physiological function for sema4D/plxnB1 signaling in RPE phagocytosis serving as attenuating brake prior to light onset whose release enables the diurnal phagocytic burst. - Source :PubMed
Exercise has been shown to be safe and effective for prostate cancer (PrCa) patients. The monitoring of resistance exercise (RE) intensity is an emerging area of interest in RE prescription. Rating of perceived exertion (RPE) is one of the most commonly used methods, but has not yet been validated in this population. Thus, the purpose of this study was to examine the relationship between RPE and RE intensity in PrCa. Data for this study were abstracted from baseline upper and lower body strength assessments from two previous trials (IDEA-P; Livestrong) in our laboratory investigating functional outcomes in PrCa patients undergoing androgen deprivation therapy (ADT). A total of 75 participants from both trials were included in this study. RPE's corresponding to 50%, 70% and 90% 1RM were extracted from the results of participants' upper and lower body 1RM strength tests. The changes in RPE across increasing intensities were assessed using separate univariate analysis of variance (ANOVA). For each ANOVA, RPE was used as the dependent variable and intensity (50%, 70%, 90%) used as the fixed factor. A univariate ANOVA revealed a significant difference (p<0.05) among the RPE values for each intensity for both upper and lower body lifts. The results of our analyses suggest that RPE values rise linearly in response to increases in exercise intensity. Our study supports the concept that RPE may be a practical training tool to accurately estimate RE intensity in PrCa survivors undergoing ADT. Practitioners may consider employing RPE to monitor and adjust RE intensity in this population. - Source :PubMed