Stamenkovic, I., Sgroi, D., Aruffo, A., Sy, M.S. & Anderson, T. The B lymphocyte adhesion molecule CD22 interacts with leukocyte common antigen CD45RO on T cells and 2,6 sialyltransferase, CD75, on B cells. Cell 66, 1133−1144
Functional maturation of B lymphocytes correlates with expression of the B lineage-specific cell surface glycoprotein CD22. Two CD22 polypeptides have been characterized and suggested to play a role in B cell-B cell interaction as well as in B cell adhesion to monocytes. In this work we provide evidence that CD22 is directly involved in the cognate interaction between B and T cells. One of the two CD22 polypeptides, CD22 beta, interacts with a specific ligand on a subpopulation of CD4+ T cells. Our results suggest that the T cell ligand of CD22 is CD45RO, an isoform of the leukocyte common antigen class of phosphotyrosine phosphatases associated with the helper T cell phenotype. We further demonstrate that CD22 recognizes a second ligand, CD75, expressed predominantly on activated B cells and shown to be a cell surface alpha 2-6 sialyltransferase.
"CD22 is closely related to leukocyte and B lymphocyte and the immune cells are assumed to be strongly associated with the ovulation processes. CD22 was expressed in B-lineage acute leukemia (Toba et al., 2003) and as a B lymphocyte adhesion molecule, CD22 was found to interact with leukocyte common antigen CD45RO on T cells (Stamenkovic et al., 1991). In rabbits, T lymphocytes dramatically increased in the uterus after ovulation, and both before and after ovulation, the cells were observed frequently in mucosa of the oviduct, cervix, and vagina (Gu et al., 2005). "
[Show abstract][Hide abstract] ABSTRACT: One of the most important traits for both animal science and livestock production is the number of offspring for a species. This study was performed to identify differentially evolved genes and their distinct functions that influence the number of offspring at birth by comparative analysis of eight monotocous mammals and seven polytocous mammals in a number of scopes: specific amino acid substitution with site-wise adaptive evolution, gene expansion and specific orthologous group. The mutually exclusive amino acid substitution among the 16 mammalian species identified five candidate genes. These genes were both directly and indirectly related to ovulation. Furthermore, in monotocous mammals, the EPH gene family was found to have undergone expansion. Previously, the EPHA4 gene was found to positively affect litter size in pigs and supports the possibility of the EPH gene playing a role in determining the number of offspring per birth. The identified genes in this study offer a basis from which the differences between monotocous and polytocous species can be studied. Furthermore, these genes may harbor some clues to the underlying mechanism, which determines litter size and may prove useful for livestock breeding strategies.
Asian Australasian Journal of Animal Sciences 04/2014; 27(4):464-70. DOI:10.5713/ajas.2013.13696 · 0.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Differences in levels of specific enzymes utilized in intracellular signalling could be a factor in the distinct signalling properties observed in memory and naive T cells. We have studied the expression of both classical and non-classical protein kinase of C (PKC) isoenzymes in CD45RA and CD45RO cells using a combination of Western blot and flow cytometric analysis. These data indicate that CD45RA cells express higher levels of PKC alpha, PKC beta and PKC delta than CD45RO cells. In addition, CD45RA+ cells show greater proliferative activity when stimulated with phorbol myristate acetate (PMA) and calcium ionophore than their CD45RO+ counterparts. Variations in the levels of these isoenzymes could be implicated in functional differences, such as proliferation and cytokine production, in these cell subsets.
"On T cells, various isoforms distinguish T helper cell subsets (Bottomly et al., 1989) and resting or activated T cells (Byrne et al., 1988). Physiological ligands of CD45 have not been definitively established, but CD45 interacts with the B cell antigen CD22 (Stamenkovic et al., 1991), which binds to many plasma membrane proteins that are sialylated (Sgroi et al., 1993). "
[Show abstract][Hide abstract] ABSTRACT: Despite the differences in the antigens that they recognize and in the effector functions they carry out, B and T lymphocytes utilize remarkably similar signal transduction components to initiate responses. They both use oligomeric receptors that contain distinct recognition and signal transduction subunits. Antigen receptors on both cells interact with at least two distinct families of PTKs via common sequence motifs, ARAMs, in the cytoplasmic tails of their invariant chains, which have likely evolved from a common evolutionary precursor. Coreceptors appear to serve to increase the sensitivity of both of these receptor systems through events that influence ligand binding and signal transduction. The critical role of tyrosine phosphorylation of downstream signaling components, such as phospholipase C, is the net result of changes in the balance of the action of antigen receptor-regulated PTKs and PTPases. The identification of downstream effectors, including calcineurin and Ras, that regulate cellular responses, such as lymphokine gene expression, promises the future possibility of connecting the complex pathway from the plasma membrane to the nucleus in lymphocytes. Insight gained from studies of the signaling pathways downstream of TCR and BCR stimulation is likely to contribute significantly to future understanding of mechanisms responsible for lymphocyte differentiation and for the discrimination of self from nonself in developing and mature cells.
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