China
Africa
Explore chapters and articles related to this topic
Hereditary Papillary Renal Cell Cancer
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Expressed by epithelial cells at the plasma membrane, the extracellular portion of MET consists of the Sema domain (homology to semaphorins, including the full α-subunit and the N-terminal part of the β-subunit), cysteine-rich MET-related sequence (MRS domain), glycine-proline-rich repeats (G-P repeats), and four immunoglobulin-plexin-transcription (IPT) repeats (Ig domains); while the intracellular region of MET comprises the juxtamembrane (JM) domain (including a serine residue Ser 985 for inhibiting the receptor kinase activity upon phosphorylation, a tyrosine Tyr 1003 for MET polyubiquitination, endocytosis, and degradation upon interaction with the ubiquitin ligase CBL), tyrosine kinase domain (consisting of Tyr 1234 and Tyr 1235, which are transphosphorylated after MET activation), and carboxyterminal docking sites (containing two crucial tyrosines, Tyr 1349 and Tyr 1356, which are inserted into the multisubstrate docking site, capable of recruiting downstream adapter proteins with Src homology-2 [SH2] domains) [7].
Normal and Abnormal Development of the Biliary Tree
Published in Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso, The Pathophysiology of Biliary Epithelia, 2020
Most recendv, a gene on 6p21.1-p12 has been identified for autosomal recessive polycystic kidney disease.88,89 This large and complex gene extends over 469 kb, and in a minimum of 86 exons encodes a member of a novel class of proteins that share structural features with hepatocyte growth factor receptor and plexins. These in turn belong to a superfamily of proteins involved in regulation of cell proliferation and of cellular adhesion and repulsion; a class of proteins of considerable interest for organogenesis.
Osteoimmunology in Aging
Published in Shamim I. Ahmad, Aging: Exploring a Complex Phenomenon, 2017
Lia Ginaldi, Daniela Di Silvestre, Maria Maddalena Sirufo, Massimo De Martinis
Many other receptor pathways, most of which are shared by immune cells, interact with RANK, some co-stimulators and others inhibitors. The inhibitor receptor system ephrin (Eph) B2/B4 allows the passage of signals bidirectionally between osteoclasts and osteoblasts [54]. It inhibits osteoclast differentiation by blocking c-fos and the NFATc1 transcriptional cascade in osteoclast cell lineage and contemporaneously favors the coupling of bone formation and resorption through the induction of osteogenetic regulatory genes in osteoblasts [55]. The ephrinB2/ephrinB4 binding therefore functions as a coupling factor in bone remodeling process [56]. Other coupling factors are semaphorins, glycoproteins involved in several biological processes such as immune response, tumor progression, and bone remodeling, among others [57–59]. Semaphorin4D (Sema4D) expressed in osteoclasts binds to its osteoblast receptor (Plexin-B1) inhibiting IGF-1 pathway, essential for osteoblast differentiation [60], whereas Sema3A in osteoblasts is an inhibitor of osteoclastogenesis [61]. During bone remodeling osteoclasts inhibit bone formation by expressing Sema4D, in order to initiate bone resorption, whereas osteoblasts express Sema3A that suppresses bone resorption, prior to bone formation.
Semaphorin 4D as a guidance molecule in the immune system
Published in International Reviews of Immunology, 2021
The classic receptors for Sema4D are molecules of plexin family [2, 3, 6], and the classic signal from these receptors is associated with cytoskeleton rearrangement. It is the plexin receptors that mediate the key effects of Sema4D in nervous and cardiovascular systems, such as axon guidance or the direction of endothelial cell migration [2, 3, 6, 7]. Plexins are expressed by many types of cells and tissues providing a huge variety of Sema4D effects. The only exception is the immune system, where the key receptor for Sema4D is CD72, a non-canonical molecule that does not belong to the plexin family [10]. CD72 is expressed by different immune cells – B lymphocytes, monocytes/macrophages, dendritic cells, and these cells are considered as the main targets of Sema4D in the immune system. Accordingly, studies of the immunoregulatory activity of semaphorin are focused almost exclusively on its CD72-dependent effects [5, 10–12]. However, the classic plexin receptors for Sema4D attributed traditionally to non-immune tissues are also present on the membrane of immune cells [13–16] and should participate in the control of their activity. Since the affinity of the plexin receptors is almost two orders of magnitude higher than that of CD72, they will respond to a much lower concentrations of semaphorin. Therefore, plexin-dependent effects of Sema4D in the immune system require special attention, and its role in the control of immune cell migration is of primary interest, based on classic semaphorin effects in non-immune tissues.
Gene expression of semaphorin-3A, semaphorin-7A, neuropilin-1, plexin-C1, and β1 integrin in treated-multiple sclerosis patients
Published in Neurological Research, 2020
Shima Shapoori, Ghasem Mosayebi, Mohsen Ebrahimi Monfared, Ali Ghazavi, Behzad Khansarinejad, Iman Farahani, Ali Ganji
Plexin-C1, as one of the receptors of Sema7A, is a cell surface receptor and a member of plexin family, which has been recently known to be associated with acute inflammation. Based on the current study, inflammatory responses can be debilitated by blocking plexin-C1 [32]. Contrary to the study by Konig and colleagues, our results depicted a significant reduction in plexin-C1 gene expression among treatment-naive patients, compared to the healthy controls, while there was a significant increase in MS patients after treatment with high-dose IFN-β1a, IFN-β1b, and GA. Additionally, another receptor of Sema7A is α1β1 integrin (CD49a, VLA1), which belongs to the integrin family and plays a major role in Sema7A signaling [33].