Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0393754 (HSA)
 2,996 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the mouse heat stable antigen (HSA or mouse CD24) shows tissue-specific as well as developmental regulation. During the maturation of several hematopoietic lineages, HSA expression is generally high in immature precursor cells and low or absent in terminally differentiated cells. We present evidence suggesting that this regulation of the HSA gene (Cd24a) occurs at the transcriptional level. In addition, sequence and methylation analysis of the Cd24a promoter revealed characteristics of both "housekeeping" and tissue-specific promoters, including a methylation-free, HpaII tiny fragment (HTF) island, multiple putative SP1 and AP-2 consensus binding sites, and a TATA box. Functional analysis of a 0.6-kilobase DNA fragment containing these elements fused to the CAT reporter gene in transient transfection experiments showed activity in both HSA expressing and non-expressing cell lines with a strength similar to that of the herpes-simplex virus-thymidine kinase promoter. Large fragments from the flanking region of the Cd24a promoter did not influence the ubiquitous nature of this promoter. Finally, we mapped the Cd24a, Cd24b, and Cd24c genes to mouse chromosomes 10, 8, and 14 respectively.
 ...
PMID:The heat stable antigen (mouse CD24) gene is differentially regulated but has a housekeeping promoter. 822 59

CD22 is a B cell-restricted surface molecule which may play an important role in interactions between B cells and other cells and in regulating signals through the B cell receptor (BCR) complex. Here we have examined whether the mouse is a suitable in vivo model for studying CD22 functions. In primary and secondary lymphoid organs of adult mice CD22 is on all mature B cells, including resting IgM+IgD+ B cells, IgG+ HSA(lo) memory B cells, syndecan+ plasma cells and CD5+ B cells, but it is not on immature IgM+IgD- B cells. Biochemical analysis revealed that murine CD22 is associated with the IgM receptor in some, but not all, CD22+ B leukemic and lymphoma cell lines; as with human CD22, murine CD22 is rapidly phosphorylated on tyrosine after ligation of the BCR. In the CD22- murine pro-B cell line, FEMCL, CD22 expression was inducible by treatment with phorbol 12-myristate 13-acetate. A genomic fragment of the cd22b allele containing 1.3 kb 5' of exon 1 was sequenced in order to identify potential DNA regulatory elements in the CD22 promoter region. Consensus sequences for transcription factor binding sites including PU.1, AP-1, AP-2, C/EBP and SP-1 were present, but no classical TATA elements or initiator motifs were evident at relevant positions. The 1.3-kb promoter fragment 5' of exon 1 was sufficient for directing basal promoter activity in B and T cells. There was no significant sequence similarity between the murine and human cd22 gene promoters, although both contain repetitive elements and Sp-1 and AP1 binding sites. Thus, murine CD22 shares a number of features with human CD22 and the mouse provides a suitable model system for elucidating the function of CD22 in vivo.
 ...
PMID:Characterization of the expression and gene promoter of CD22 in murine B cells. 897 19

Aggregation of the high-affinity immunoglobulin E (IgE) receptor (FcepsilonRI), expressed on mast cells and basophils, initiates the immediate hypersensitivity reaction. Aggregated FcepsilonRI has been reported to rapidly migrate to lipid rafts in RBL-2H3 cells. We confirmed that aggregated FcepsilonRI is found in the lipid raft fractions of cellular lysates. Furthermore, we show that the cross-linked FcepsilonRI remains associated with detergent-resistant structures upon internalization. Previous morphological studies have reported that aggregated FepsiloncRI is endocytosed via clathrin-coated pits, which in general are not lipid raft associated. To address this apparent discrepancy, we employed siRNA to suppress expression of components of the clathrin-mediated internalization machinery, namely, clathrin heavy chain, and the AP-2 (alpha-adaptin or mu2-subunit). Transferrin receptor (TfR) is endocytosed by a clathrin-mediated process and, as expected, each transfected siRNA caused a two to threefold elevation of TfR surface expression and almost completely inhibited its endocytosis. In contrast, there was no effect on surface expression levels of FcepsilonRI nor on the endocytosis of the dinitrophenyl-human serum albumin (DNP-HSA)/IgE/FcepsilonRI complex. On the contrary, internalization of DNP-HSA/IgE/FcepsilonRI was inhibited by overexpression of a dominant-negative dynamin mutant. We conclude that internalization of cross-linked FcRI does not require the AP-2/clathrin complex but is dynamin-dependent and may be lipid raft mediated.
 ...
PMID:The high-affinity immunoglobulin-E receptor (FcepsilonRI) is endocytosed by an AP-2/clathrin-independent, dynamin-dependent mechanism. 1663 89