In vitro antimutagenicity of capsaicin toward heterocyclic amines in Salmonella typhimurium strain TA98.

Capsicum fruits are widely consumed as a component of the human diet. Capsaicin is the principle substance responsible for their hot, pungent taste. Heterocyclic amines (HCAs) are formed during cooking of meats and are mutagenic/carcinogenic compounds.

In vivo cloning and characterization of a new growth suppressor protein TOE1 as a direct target gene of Egr1.

Egr1, an immediate early transcription factor, responds to diverse stimuli and affects gene transcription to accomplish its biological effects. One important effect of Egr1 expression is to decrease the growth and tumorigenic potential of several tumor cell types. To identify important Egr1 target genes, we have adapted a methodology involving formaldehyde-induced protein-DNA cross-linking, chromatin immunoprecipitation, and multiplex PCR.

Egr1 promotes growth and survival of prostate cancer cells. Identification of novel Egr1 target genes.

In the majority of aggressive tumorigenic prostate cancer cells, the transcription factor Egr1 is overexpressed. We provide new insights of Egr1 involvement in proliferation and survival of TRAMP C2 prostate cancer cells by the identification of several new target genes controlling growth, cell cycle progression, and apoptosis such as cyclin D2, P19ink4d, and Fas. Egr1 regulation of these genes, identified by Affymetrix microarray, was confirmed by real-time PCR, immunoblot, and chromatin immunoprecipitation assays.

Sweet solution: sugars to the rescue.

Sugar pills are usually placebos, but Smith et al. (2002, this issue) use one to rescue designer mice unable to make GDP-Fucose. Dietary fucose enters a salvage pathway and spares the mice.

Low-molecular-weight protein tyrosine phosphatase and human disease: in search of biochemical mechanisms.

A major challenge in the post-genomic era is to identify the physiological functions of genes and elucidate the molecular basis for human disease. Genetic polymorphisms offer a convenient avenue for these efforts by providing evidence for the involvement of a given gene in human pathophysiology. Here we review the current evidence linking the low-molecular-weight protein tyrosine phosphatase (LMPTP) to several common diseases, including allergy, asthma, obesity, myocardial hypertrophy, and Alzheimer's disease.

Activation of ZAP-70 through specific dephosphorylation at the inhibitory Tyr-292 by the low molecular weight phosphotyrosine phosphatase (LMPTP).

The ZAP-70 protein-tyrosine kinase plays a central role in signaling from the T cell antigen receptor. Recruitment and activation of ZAP-70 are transient and are terminated by phosphorylation of negative regulatory tyrosine residues and dephosphorylation of positively acting sites. We report that the low molecular weight protein-tyrosine phosphatase (LMPTP) specifically dephosphorylates the negative regulatory Tyr-292 of ZAP-70, thereby counteracting inactivation of ZAP-70.

Cripto: a tumor growth factor and more.

Cripto, a growth factor with an EGF-like domain, and the first member of the EGF-CFC family of genes to be sequenced and characterized, contributes to deregulated growth of cancer cells. A role for Cripto in tumor development has been described in the human and the mouse. Members of the EGF-CFC family are found only in vertebrates: CFC proteins in zebrafish, Xenopus, chick, mouse and human have been characterized and indicate some common general functions in development.

Protein tyrosine phosphatases.

The molecular mechanisms of signal transduction have been at the focus of increasingly intense scientific research. As a result, our understanding of protein tyrosine kinase-mediated signaling has advanced at an unprecedented pace during the past decade. In contrast, the study of protein tyrosine phosphatases has lagged behind, but is now gathering momentum and is predicted to become a "hot topic" in the field within the next few years.

Inhibition of T cell antigen receptor signaling by VHR-related MKPX (VHX), a new dual specificity phosphatase related to VH1 related (VHR).

A cDNA encoding a novel, human, dual-specific protein phosphatase was identified in the Incyte data base. The open reading frame predicted a protein of 184 amino acids related to the Vaccinia virus VH1 and human VH1-related (VHR) phosphatases. Expression VHR-related MKPX (VHX) was highest in thymus, but also detectable in monocytes and lymphocytes.

Novel vectors for co-expression of two proteins in E. coli.

Two new vectors, pAC28 and pEGST, for the co-expression of recombinant genes in E. coli were developed. This two-plasmid system allows for an efficient expression and purification of large amounts of protein-protein complexes formed in bacterial cells.

Chondroitin sulfate and cytoplasmic domain-dependent membrane targeting of the NG2 proteoglycan promotes retraction fiber formation and cell polarization.

Targeting of the NG2 proteoglycan to cellular retraction fibers was studied by expressing mutant NG2 molecules lacking specific structural elements of the proteoglycan. Both the cytoplasmic domain and the chondroitin sulfate chain of NG2 appear to have roles in sorting NG2 to subcellular microdomains destined to become retraction fibers. Neither of these structural features alone is sufficient to allow optimal targeting of NG2 to retraction fibers, but together they promote efficient localization of the proteoglycan to these sites.

Notl-Msell methylation-sensitive amplied fragment length polymorhism for DNA methylation analysis of human cancers.

We have applied a methylation-sensitive restriction endonuclease, NotI, to the existing amplified fragment length polymorphism (AFLP) method and developed NotI-MseI methylation-sensitive-AFLP (MS-AFLP). NotI-MseI MS-AFLP allows the analysis of DNA methylation alterations at the NotI sites scattered over the genome. Hypermethylation and hypomethylation are visualized by the decrease and increase in the band intensity of DNA fingerprints.

Molecular genetic basis of porcine histo-blood group AO system.

Histo-blood group A and B antigens are oligosaccharide antigens important in transfusion and transplantation medicine. The final steps in the synthesis of these antigens are catalyzed by glycosyltransferases encoded by the functional alleles at the ABO locus. Humans have 3 major alleles (A, B, and O), whereas pigs are known to have only A and O alleles.

Murine equivalent of the human histo-blood group ABO gene is a cis-AB gene and encodes a glycosyltransferase with both A and B transferase activity.

We have cloned murine genomic and complementary DNA that is equivalent to the human ABO gene. The murine gene consists of at least six coding exons and spans at least 11 kilobase pairs. Exon-intron boundaries are similar to those of the human gene.

Abnormal vitamin B6 metabolism in alkaline phosphatase knock-out mice causes multiple abnormalities, but not the impaired bone mineralization.

The tissue non-specific alkaline phosphatase (TNAP) knock-out mouse is a model of infantile hypophosphatasia displaying impaired bone mineralization, epileptic seizures, apnoea, abnormal apoptosis in the thymus, abnormal lumbar nerve roots, and postnatal death. Administration of vitamin B6 suppresses the epileptic seizures in TNAP-/- mice. This paper examines to what extent the diverse abnormalities seen in these mice are due to impaired utilization of vitamin B6, using two complementary approaches: administration of vitamin B6 to TNAP null mice and deprivation of vitamin B6 in wild-type and TNAP heterozygous mice.

Altered Ets transcription factor activity in prostate tumor cells inhibits anchorage-independent growth, survival, and invasiveness.

The Ets family of transcription factors are important downstream targets in cellular transformation, as altering Ets activity has been found to reverse the transformed phenotype of Ras transformed mouse fibroblasts and of several human tumor cell lines. To determine whether Ets factors are important targets in the largely uncharacterized aberrant signaling in prostate cancer, we have altered Ets activity in the prostate tumor cell line PPC-1, by stable expression of either full-length Ets2, or a dominant inhibitor of Ets activity, the Ets2 DNA binding domain (Ets2DBD). Analysis of multiple independent clonal cell lines revealed that expression of either Ets2 or the Ets2DBD inhibited the anchorage-independent growth of PPC-1 cells up to 20-fold.

Inhibitory role for dual specificity phosphatase VHR in T cell antigen receptor and CD28-induced Erk and Jnk activation.

The 21-kDa dual specific protein phosphatase VH1-related (VHR) is one of the smallest known phosphatases, and its function has remained obscure. We report that this enzyme is expressed in lymphoid cells and is not induced by T cell antigen receptor like other dual specificity phosphatases. Introduction of exogenous VHR into Jurkat T cells caused a marked decrease in the transcriptional activation of a nuclear factor of activated T cells and an activator protein-1-driven reporter gene in response to ligation of T cell antigen receptors.

Extracellular signals and scores of phosphatases: all roads lead to MAP kinase.

MAP kinases function as key signal integration points for a vast number of external stimuli that affect the life and death of cells and are therefore subject to rigorous regulation. Here we review the numerous protein phosphatases that directly counteract MAP kinase activation. To simplify the complexity, we attempt to integrate the information into a 'sequential phosphatase model' of MAP kinase regulation.

Mutational inactivation of the proapoptotic gene BAX confers selective advantage during tumor clonal evolution.

A remarkable instability at simple repeated sequences characterizes gastrointestinal cancer of the microsatellite mutator phenotype (MMP). Mutations in the DNA mismatch repair gene family underlie the MMP, a landmark for hereditary nonpolyposis colorectal cancer. These tumors define a distinctive pathway for carcinogenesis because they display a particular spectrum of mutated cancer genes containing target repeats for mismatch repair deficiency.

Subcellular localization of intracellular protein tyrosine phosphatases in T cells.

A high protein tyrosine phosphatase (PTPase) activity is required to maintain circulating T lymphocytes in a resting phenotype, and to limit the initiation of T cell activation. We report that 15 of the currently known 24 intracellular PTPases are expressed in T cells, namely HePTP, TCPTP, SHP1, SHP2, PEP, PTP-PEST, PTP-MEG2, PTEN, PTPH1, PTP-MEG1, PTP36, PTP-BAS, LMPTP, PRL-1 and OV-1. Most were found in the cytosol and many were enriched at the plasma membrane.

Molecular genetics of ABO.

This year commemorates the 100th anniversary of the discovery of the ABO blood group system by Karl Landsteiner. His findings of red cell agglutination by serum and recognition of blood groups laid the scientific basis for safe practice of blood transfusion. Even though dozens of blood systems have been identified, the ABO system still remains to be one of the most important systems in transfusion medicine.

Binding of the NG2 proteoglycan to kringle domains modulates the functional properties of angiostatin and plasmin(ogen).

Interactions of the developmentally regulated chondroitin sulfate proteoglycan NG2 with human plasminogen and kringle domain-containing plasminogen fragments have been analyzed by solid-phase immunoassays and by surface plasmon resonance. In immunoassays, the core protein of NG2 binds specifically and saturably to plasminogen, which consists of five kringle domains and a serine protease domain, and to angiostatin, which contains plasminogen kringle domains 1-3. Apparent dissociation constants for these interactions range from 12 to 75 nm.