| LGALS8 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Aliases | LGALS8 , Gal-8, PCTA-1, PCTA1, Po66-CBP, galectin 8 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 606099; MGI: 1928481; HomoloGene: 31386; GeneCards: LGALS8; OMA:LGALS8 - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
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| Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Galectin-8 is a protein of the galectin family that in humans is encoded by the LGALS8 gene. [5] [6] [7]
This gene encodes a member of the galectin family. Galectins are beta-galactoside-binding animal lectins with conserved carbohydrate recognition domains. The galectins have been implicated in many essential functions including development, differentiation, cell-cell adhesion, cell-matrix interaction, growth regulation, apoptosis, and RNA splicing. This gene is widely expressed in tumoral tissues and seems to be involved in integrin-like cell interactions. Alternatively spliced transcript variants encoding different isoforms have been identified. [7]
Galectin-8, interacts with the mTOR regulatory system composed of SLC38A9, Ragulator, RagAB, RagCD. [8] Galectin-8 controls mTOR causing its inactivation and dissociation from damaged lysosomes, hence transducing the breach of the lysosomal membrane to mTOR. [8] The physiological consequences of mTOR inhibition following lysosomal membrane damage [8] encompass autophagy and metabolic switching.
Circulating galectin levels in the serum of healthy individuals typically range between 0.1 and 166.3 ng/mL, with a median concentration of approximately 6 ng/mL. In cancer patients, these levels can increase up to fivefold. [9] [10]
Galectin-8 has a complex role in cancer, sometimes being protumorigenic and other times anti-tumorigenic. [11]
Galectin-8 has recently been shown to have a role in cellular defence, against both bacterial cytosolic infection and vacuolar damage. [12] Many intracellular bacteria, such as S. enterica serovar Typhimurium and S. flexneri prefer to replicate inside and outside of the vacuole safety respectively, yet these vacuoles may become damaged, exposing bacteria to the host cell cytoplasm. It has been shown that the binding of galectin-8 to the damaged vacuole can recruit autophagy adaptors such as NDP52 leading to the formation of an autophagosome and subsequent bacterial destruction. [12] As knockout experiments of galectin-8 leads to more successful cytosolic replication by S. enterica serovar Typhimurium, it is thought that galectin-8 acts as a danger receptor in defence against intracellular pathogens. [12] [13]
Galectin-8 has also been used to study endosomal disruption in the development of nanoscale drug delivery systems. Many drug delivery systems carrying large molecule drugs, such as antisense oligonucleotides, siRNA, peptides, and therapeutic proteins, are engineered to be pH-responsive, and disrupt the endosomal membrane because of the lower pH found within progressively acidifying endosomes. Galectin-8 can be tagged with a fluorophore to track these disrupted endosomal membranes, especially when coupled with automated microscopy. [14]
Galectin-8 has been shown to interact with CD44 [15] , CD49d, [16] CD29 [16] and CD49c. [16] It also interacts with components of the mTORC1 complex. [8]
Integrins are transmembrane receptors that help cell–cell and cell–extracellular matrix (ECM) adhesion. Upon ligand binding, integrins activate signal transduction pathways that mediate cellular signals such as regulation of the cell cycle, organization of the intracellular cytoskeleton, and movement of new receptors to the cell membrane. The presence of integrins allows rapid and flexible responses to events at the cell surface.
Cell adhesion molecules (CAMs) are a subset of cell surface proteins that are involved in the binding of cells with other cells or with the extracellular matrix (ECM), in a process called cell adhesion. In essence, CAMs help cells stick to each other and to their surroundings. CAMs are crucial components in maintaining tissue structure and function. In fully developed animals, these molecules play an integral role in generating force and movement and consequently ensuring that organs are able to execute their functions normally. In addition to serving as "molecular glue", CAMs play important roles in the cellular mechanisms of growth, contact inhibition, and apoptosis. Aberrant expression of CAMs may result in a wide range of pathologies, ranging from frostbite to cancer.
In mammalian cells, vinculin is a membrane-cytoskeletal protein in focal adhesion plaques that is involved in linkage of integrin adhesion molecules to the actin cytoskeleton. Vinculin is a cytoskeletal protein associated with cell-cell and cell-matrix junctions, where it is thought to function as one of several interacting proteins involved in anchoring F-actin to the membrane.
ICAM-1 also known as CD54 is a protein that in humans is encoded by the ICAM1 gene. This gene encodes a cell surface glycoprotein which is typically expressed on endothelial cells and cells of the immune system. It binds to integrins of type CD11a / CD18, or CD11b / CD18 and is also exploited by rhinovirus as a receptor for entry into respiratory epithelium.
Galectins are a class of proteins that bind specifically to β-galactoside sugars, such as N-acetyllactosamine, which can be bound to proteins by either N-linked or O-linked glycosylation. They are also termed S-type lectins due to their dependency on disulphide bonds for stability and carbohydrate binding. There have been about 15 galectins discovered in mammals, encoded by the LGALS genes, which are numbered in a consecutive manner. Only galectin-1, -2, -3, -4, -7, -7B, -8, -9, -9B, 9C, -10, -12, -13, -14, and -16 have been identified in humans. Galectin-5 and -6 are found in rodents, whereas galectin-11 and -15 are uniquely found in sheep and goats. Members of the galectin family have also been discovered in other mammals, birds, amphibians, fish, nematodes, sponges, and some fungi. Unlike the majority of lectins they are not membrane bound, but soluble proteins with both intra- and extracellular functions. They have distinct but overlapping distributions but found primarily in the cytosol, nucleus, extracellular matrix or in circulation. Although many galectins must be secreted, they do not have a typical signal peptide required for classical secretion. The mechanism and reason for this non-classical secretion pathway is unknown.
In molecular biology, CD18 is an integrin beta chain protein that is encoded by the ITGB2 gene in humans. Upon binding with one of a number of alpha chains, CD18 is capable of forming multiple heterodimers, which play significant roles in cellular adhesion and cell surface signaling, as well as important roles in immune responses. CD18 also exists in soluble, ligand binding forms. Deficiencies in CD18 expression can lead to adhesion defects in circulating white blood cells in humans, reducing the immune system's ability to fight off foreign invaders.
Integrin beta-1 (ITGB1), also known as CD29, is a cell surface receptor that in humans is encoded by the ITGB1 gene. This integrin associates with integrin alpha 1 and integrin alpha 2 to form integrin complexes which function as collagen receptors. It also forms dimers with integrin alpha 3 to form integrin receptors for netrin 1 and reelin. These and other integrin beta 1 complexes have been historically known as very late activation (VLA) antigens.
CD49d is an integrin alpha subunit. It makes up half of the α4β1 lymphocyte homing receptor.
Integrin alpha-3 is a protein that in humans is encoded by the ITGA3 gene. ITGA3 is an integrin alpha subunit. Together with beta-1 subunit, it makes up half of the α3β1 integrin duplex that plays a role in neural migration and corticogenesis, acted upon by such factors as netrin-1 and reelin.
CD9 is a gene encoding a protein that is a member of the transmembrane 4 superfamily also known as the tetraspanin family. It is a cell surface glycoprotein that consists of four transmembrane regions and has two extracellular loops that contain disulfide bonds which are conserved throughout the tetraspanin family. Also containing distinct palmitoylation sites that allows CD9 to interact with lipids and other proteins.
Cysteine-rich angiogenic inducer 61 (CYR61) or CCN family member 1 (CCN1), is a matricellular protein that in humans is encoded by the CYR61 gene.
C-type lectin domain family 4 member M is a protein that in humans is encoded by the CLEC4M gene. CLEC4M has also been designated as CD299.
Integrin, beta 4 (ITGB4) also known as CD104, is a human gene.
Neural precursor cell expressed developmentally down-regulated protein 9 (NEDD-9) is a protein that in humans is encoded by the NEDD9 gene. NEDD-9 is also known as enhancer of filamentation 1 (EF1), CRK-associated substrate-related protein (CAS-L), and Cas scaffolding protein family member 2 (CASS2). An important paralog of this gene is BCAR1.
Lysosomal-associated membrane protein 1 (LAMP-1) also known as lysosome-associated membrane glycoprotein 1 and CD107a, is a protein that in humans is encoded by the LAMP1 gene. The human LAMP1 gene is located on the long arm (q) of chromosome 13 at region 3, band 4 (13q34).
Galectin-3-binding protein is a protein that in humans is encoded by the LGALS3BP gene.
Galectin-9 was first isolated from mouse embryonic kidney in 1997 as a 36 kDa beta-galactoside lectin protein. Human galectin-9 is encoded by the LGALS9 gene.
Integrin alpha-9 is a protein that in humans is encoded by the ITGA9 gene. Cytogenetic location: 3p22.2
Arginylglycylaspartic acid (RGD) is the most common peptide motif responsible for cell adhesion to the extracellular matrix (ECM), found in species ranging from Drosophila to humans. Cell adhesion proteins called integrins recognize and bind to this sequence, which is found within many matrix proteins, including fibronectin, fibrinogen, vitronectin, osteopontin, and several other adhesive extracellular matrix proteins. The discovery of RGD and elucidation of how RGD binds to integrins has led to the development of a number of drugs and diagnostics, while the peptide itself is used ubiquitously in bioengineering. Depending on the application and the integrin targeted, RGD can be chemically modified or replaced by a similar peptide which promotes cell adhesion.
Galectin-3 is a protein that in humans is encoded by the LGALS3 gene. Galectin-3 is a member of the lectin family, of which 14 mammalian galectins have been identified.
