"SHP-1 (also designated as SHPTP-1, SHP, HCP and PTP1C, PTPN6) is a 68 kDa cytosolic PTP predominantly expressed in hematopoietic and epithelial cells   . The human SHP-1 gene is located on chromosome 12p13   and consists of 17 exons and 16 introns, spanning 17 kb of DNA (6). SHP-1 contains two tandem src-homology 2 (SH2) domains, three potential SH3-binding motifs (PxxP) for binding, a catalytic phosphatase domain and a C-terminal tail with two sites for tyrosine phosphorylation     . "
[Show abstract][Hide abstract] ABSTRACT: We identified 7 SHP-1 transcripts using epithelial cancer-derived cell lines. Four were shown to utilize the epithelial promoter 1 to transcribe a full-length, a partial (exon 3) or complete (exons 3 & 4) deletion of the N-SH2 domain, and also a non-coding transcript having a stop codon caused by a frame shift due to intron 2 retention. Three additional transcripts were shown to utilize the hematopoietic promoter 2 to transcribe a full-length, a partial (exon 3) deletion of the N-SH2 domain and a non-coding transcript with intron 2 retention. We show that endogenous proteins corresponding to the open-reading-frame (ORF) transcripts are produced. Using GST-fusion proteins we show that each of the ORF SHP-1 transcripts has phosphatase activity and isoforms with an N-SH2 deletion have increased phosphatase activity and novel protein-protein interactions. This study is the first to document utilization of promoter 2 by SHP-1 transcripts and a noncoding transcript in human epithelial cells.
"The human SHP-1 gene is located on chromosome 12p13 (Plutzky et al., 1992; Matsushita et al., 1999). It consists of 17 exons and spans approximately 17 kb of DNA with a transcription size of 2.4– 2.6 kb (Fig. 1). "
[Show abstract][Hide abstract] ABSTRACT: SHP-1, an SH2 domain-containing protein tyrosine phosphatase, is primarily expressed in hematopoietic cells and behaves as a key regulator controlling intracellular phosphotyrosine levels in lymphocytes. SHP-1 has been proposed as a candidate tumor suppressor gene in lymphoma, leukemia and other cancers, as it functions as an antagonist to the growth-promoting and oncogenic potentials of tyrosine kinase. The decreased levels of SHP-1 protein and SHP-1 mRNA observed in various leukemia and lymphoma cell lines have been attributed to either the methylation of the promoter region of the SHP-1 gene or the post-transcriptional block of SHP-1 protein synthesis. In contrast, SHP-1 protein is normally or over-expressed in some non-lymphocytic cell lines, such as prostate cancer, ovarian cancer and breast cancer cell lines. SHP-1 expression also is decreased in some breast cancer cell lines with negative expression of estrogen receptor as well as some prostate and colorectal cancer cell lines. These data suggest that SHP-1 can play either negative or positive roles in regulating signal transduction pathways. Dysfunction in SHP-1 regulation can cause abnormal cell growth and induce different kinds of cancers. In this paper, we summarize recent studies on the expression and regulation of SHP-1 protein and its pathological function in the development of lymphoma, leukemia and other cancers.
[Show abstract][Hide abstract] ABSTRACT: The crucial role of costimulatory molecules, CD28, CTLA-4, CD80 and CD86, for T cell activation and inhibition has been established. In the previous study, we reported the results of a polymorphism screening of human CTLA-4 gene. In this study, we screened for polymorphisms of human CD28, CD80 and CD86 genes, and detected that polymorphisms were tested for the association with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Variations were identified in the coding regions of CD80 (452G/A, 614C/G and 864A/G) and CD86 (1057A/G), while no variation was observed in the coding region of CD28. The variations at CD80 position 452 and CD86 position 1057 were present in a substantial proportion of the Japanese population, and were considered to be single nucleotide polymorphisms within the coding sequence (cSNPs). CD80 864 (G-->A) leads to the amino acid substitution N186D, and CD86 1057 (A-->G) results in A304T substitution. Furthermore, in the analysis of CD80 5'-flanking region, six SNPs, -454C/A, -387T/C, -232G/A, -79G/C, -7T/C and /A, and one insertion, -558ins (CATGA), were identified. The combination of these variations was found to constitute four promoter alleles of CD80. None of the observed variations was significantly associated with RA or SLE. Further studies will be of particular interest to examine the functional difference of the promoter alleles for the transcriptional activity of CD80, as well as the evolutionary pathway of the four alleles.
Genes and Immunity 10/2000; 1(7):428-34. DOI:10.1038/sj.gene.6363704 · 2.91 Impact Factor
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