Biomedical subjects

J D Shi

Publications and source records attributed to J D Shi.

17 recordsLinked to original sources

PubMed2001

Molecular cloning and characterization of the mouse and human TUSP gene, a novel member of the tubby superfamily.

We report here the cloning and characterization of a novel gene belonging to the tubby superfamily proteins (TUSP) in mouse and human. The mouse Tusp cDNA is 9120 bp in length and encodes a deduced protein of 1547 amino acids, while the human TUSP gene is 11,127 bp and encodes a deduced protein of 1544 amino acids. The human and mouse genes are 87% identical for their nucleotide sequences and 85% identical for their amino acid sequences. The protein sequences of these genes are 40-48% identical to other tubby family proteins at the C-terminal conserved 'tubby domain'. In addition, the TUSP proteins contain a tubby signature motif (FXGRVTQ), two bipartite nuclear localization signals (NLSs) at the C-terminal, two proline-rich regions, one WD40 repeat region and one suppressor of cytokines signaling domain. Transfection assay with green fluorescent protein-tagged TUSP expression constructs showed that the complete TUSP protein and the N-terminal portion of TUSP are localized in the cytoplasm but the C-terminal portion with the two NLSs produced distinct dots or spots localized in the cytoplasm. Northern blotting analysis showed that the major transcript with the complete coding sequence is expressed mainly in the brain, skeletal muscle, testis and kidney. Radiation hybrid mapping localized the mouse gene to chromosome 17q13 and the human TUSP gene to chromosome 6q25-q26 near the type 1 diabetes gene IDDM5. However, association analysis in diabetic families with a polymorphic microsatellite marker did not show any evidence for association between TUSP and type 1 diabetes. The precise biological function of the tubby superfamily genes is still unknown; the highly conserved tubby domain in different species, however, suggests that these proteins must have fundamental biological functions in a wide range of multi-cellular organisms.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Molecular cloning and characterization of a novel mammalian endo-apyrase (LALP1).

Here we describe the cloning, localization, and characterization of a novel mammalian endo-apyrase (LALP1) in human and mouse. The predicted human LALP1 gene encodes a 604-amino acid protein, whereas the mouse Lalp1 gene encodes a 606-amino acid protein. The human and mouse genes have 88% amino acid sequence identity. These genes share considerable homologies with hLALP70, a recently discovered mammalian lysosomal endo-apyrase. The human LALP1 gene resides on chromosome 10q23-q24 and contains 12 exons and 11 introns covering a genomic region of approximately 46 kilobase pairs. The subcellular localization and enzymatic activity of LALP1 indicated that LALP1 is indeed an endo-apyrase with substrate preference for nucleoside triphosphates UTP, GTP, and CTP.

Amino Acid Sequence↗

PubMed2001

Rapid decrease of RNA level of a novel mouse mitochondria solute carrier protein (Mscp) gene at 4-5 weeks of age.

We cloned a novel mouse gene that encodes a protein with homology to the mitochondria solute carrier proteins (Mscp). The major full-length Mscp transcript contains 4112 bp of cDNA and a deduced protein of 338 amino acids. The Mscp protein shares 50%, 40%, and 39% sequence identity with the C. elegans hypothetical protein T26089 and the yeast mitochondria carrier proteins MRS3 and MRS4, respectively. It also showed homology with the uncoupling proteins (UCP1, UCP2, and UCP3; 22%, 24%, and 29% identity, respectively). The protein has six transmembrane domains and three mitochondria energy-transfer protein signature motifs, which are conserved among all the members of mitochondria carrier protein family. Northern analysis indicated that the Mscp gene is highly expressed in the spleen. Using cDNA microarray and Northern analysis, we have shown a significant decrease of the splenic Mscp mRNA levels around 4-5 weeks of age in several mouse strains including C57BL/6J, nonobese diabetic (NOD), and several NOD-congenic mice. These results suggest that the Mscp gene is decreased during splenic lymphocyte maturation in these mice.

Amino Acid Sequence↗

PubMed1999

A humanized anti-CD3 antibody, HuM291, with low mitogenic activity, mediates complete and reversible T-cell depletion in chimpanzees.

BACKGROUND: An anti-CD3 antibody that reduces cytokine release syndrome (CRS) while maintaining immunosuppression would be a major advance in the treatment of acute allograft rejection. A humanized (Hu) anti-CD3 IgG2 Ab, HuM291 gamma2 M3 (HuM291; Protein Design Labs, Inc., Mountain View, CA), was engineered with mutations in the upper CH2 region of the Fc domain. The mutations were intended to reduce affinity for Fcgamma receptors, thought to be relevant to CRS. METHODS: In vitro studies using chimpanzee peripheral blood mononuclear cells (PBMCs) were conducted to characterize HuM291 and to establish an animal model. A multidose study was conducted in chimpanzees to evaluate the safety, pharmacokinetics, immunomodulatory activity, and immunogenicity of HuM291, when administered at doses ranging from 0.1 to 10 mg. RESULTS: HuM291 bound to and effectively downmodulated CD3 from chimpanzee PBMCs and stimulated substantially less cytokine secretion and proliferation of chimpanzee PBMCs compared with OKT3 (Orthoclone OKT3; Ortho Pharmaceutical Corp., Raritan, NJ). Multiple doses of HuM291 (0.1, 1.0, or 10 mg/dose) were not associated with adverse events, signs of toxicity, or CRS, despite cytokine release. HuM291 exhibited a long elimination t1/2 (81.5 hr) and, after three 10-mg doses, sustained serum concentrations > 1000 ng/ml were maintained for 1 week. Multiple 10-mg doses induced complete depletion of circulating CD2+CD3+ T cells for up to 10 days after the last dose; T cells recovered by Day 28. Anti-HuM291 Abs were observed in only 4 of 12 animals and were transient in 2 of those animals. CONCLUSIONS: In vitro, HuM291 is substantially less mitogenic than OKT3. In chimpanzees, HuM291 effectively depleted peripheral T cells without eliciting clinical signs of CRS, and recovered T cells were functionally normal.

Animals↗

PubMed1999

HuM291, a humanized anti-CD3 antibody, is immunosuppressive to T cells while exhibiting reduced mitogenicity in vitro.

BACKGROUND: OKT3, a mouse monoclonal antibody (Ab) specific for the human CD3 complex on T cells, is a potent immunosuppressive agent used for the treatment of acute allograft rejection. The utility of the drug has been limited by a neutralizing anti-mouse Ab response and adverse side effects resulting from T cell activation and systemic cytokine release. T cell activation is caused by OKT3-mediated cross-linking of T cells and Fc receptor-bearing cells. Studies in the mouse model have shown that global T cell activation is not necessary for immunosuppression, as Fc receptor-nonbinding anti-CD3 Abs can suppress graft rejection in the absence of the activation effects seen with Fc receptor-binding Abs. Thus, a humanized anti-CD3 antibody with a low affinity for Fc receptors might improve immunosuppressive therapy by reducing the side effects associated with OKT3. METHODS: We developed a mouse monoclonal Ab, M291, which competes with OKT3 for binding to T cells. Humanized, complementary-determining region-grafted versions of M291 featuring various Fc were engineered, including a previously described IgG2 mutant deficient in Fc receptor binding (HuM291). RESULTS: Compared with OKT3 and HuM291-IgG1, HuM291 was significantly less mitogenic to T cells in vitro and induced the release of much lower levels of the cytokines tumor necrosis factor-alpha, interferon-gamma, and interleukin-10. Despite this reduction in T cell activation, HuM291 retained the ability to modulate the CD3 complex and inhibit the mixed lymphocyte reaction. CONCLUSIONS: When evaluated in vivo, HuM291 may be an immunosuppressive agent associated with less of the acute toxicity and immunogenicity seen with OKT3 therapy.

Amino Acid Sequence↗

PubMed1999

Construction of a physical and transcript map for a 1-Mb genomic region containing the urofacial (Ochoa) syndrome gene on 10q23-q24 and localization of the disease gene within two overlapping BAC clones (<360 kb).

Urofacial (Ochoa) syndrome is an autosomal recessive disease characterized by distorted facial expression and urinary abnormalities. Previously, we mapped the UFS gene to chromosome 10q23-q24 and narrowed the interval to one YAC clone of 1410 kb. Here, we have constructed a BAC/PAC contig of the 1-Mb region using STS content mapping with 42 BAC/PAC-end sequences, 9 previously reported and 16 newly identified microsatellite markers, and 14 EST markers. A total of 26 polymorphic microsatellite markers were genotyped for 31 UFS patients from Colombia and 2 patients from the United States. Haplotype analyses suggest that the UFS gene is located within two overlapping BAC clones, a region of <360 kb of DNA sequence. We tested 42 EST markers previously mapped to the D10S1709-D10S603 interval against the BAC/PAC contig and identified 11 ESTs located in the 1-Mb region. Four of the 11 ESTs mapped to the 360-kb UFS critical region. Shotgun sequencing of the two BAC clones and BLASTN search of the EST databases revealed 3 other ESTs contained in the UFS critical region. These results will facilitate the cloning and identification of the UFS gene.

Bacteriophage P1↗

PubMed1999

Genetic homogeneity, high-resolution mapping, and mutation analysis of the urofacial (Ochoa) syndrome and exclusion of the glutamate oxaloacetate transaminase gene (GOT1) in the critical region as the disease gene.

The urofacial (Ochoa) syndrome (UFS) is a rare autosomal recessive disorder characterized by abnormal facial expression and urinary abnormalities. Previously, we mapped the gene to a genomic interval of approximately 1 cM on chromosome region 10q23-24, using families from Columbia. Here we demonstrate genetic homogeneity of the syndrome through homozygosity mapping in American patients with Irish heritage. We established a physical map and identified novel polymorphic markers in the UFS critical region. Haplotype analysis using the new markers mapped the UFS gene within one YAC clone of 1,410 kb. We also determined the precise location of the gene encoding for glutamate oxaloacetate transaminase (GOT1) within the new UFS critical region and determined its genomic structure. However, mutation analysis excluded GOT1 as a candidate for the UFS gene.

Abnormalities, Multiple↗

PubMed1999

Cloning of Aire, the mouse homologue of the autoimmune regulator (AIRE) gene responsible for autoimmune polyglandular syndrome type 1 (ASP1).

The human autoimmune regulator gene (AIRE), responsible for autoimmune polyglandular syndrome Type 1 (APS1), has recently been identified by positional cloning. Here we report the cloning of Aire, the mouse homologue of AIRE, and the characterization of its genomic structure. The complete Aire gene is contained in 14 exons and encodes a protein of 552 amino acids. The coding region shares 77% nucleotide homology and 71% protein homology with human AIRE. As in its human homologue, Aire contains two PHD-type zinc-finger motifs, suggesting that the Aire protein may act as a transcription regulator.

Amino Acid Sequence↗

PubMed1999

Expression and alternative splicing of the mouse autoimmune regulator gene (Aire).

AIRE, the gene responsible for the autoimmune polyglandular syndrome type 1 (APS1) or APECED, may act as a transcription factor according to its predicated protein structure. Here we demonstrate the low expression level of the mouse Aire gene as it is undetectable by Northern blot analyses. However, RT-PCR analyses revealed expression of Aire in mouse thymus, ovary, lung, testis, kidney and adrenal gland. Barely detectable level of RT-PCR product was also found in thyroid gland and heart but no amplification was detected in pancreas, spleen and liver. Competitive RT-PCR assays demonstrated highest expression level of Aire mRNA in thymus. In addition to the complete cDNA (Aire or Aire-1a), we identified 11 alternative splicing forms (designated as Aire-1b, Aire-1c, Aire-1d, Aire-2a, Aire-2b, Aire-2c, Aire-2d, Aire-3a, Aire-3b, Aire-3c and Aire-3d). These forms result from combinations of four alternative splicing units (exon 10, exon 11, 12 bp in exon 6 and 3 bp in exon 8). The relative abundance of these splicing forms was also determined.

Alternative Splicing↗

PubMed1999

Chromosomal localization and complete genomic sequence of the murine autoimmune regulator gene (Aire).

We have recently cloned the murine autoimmune regulator (Aire) gene, the homologue of human AIRE responsible for the autoimmune polyglandular syndrome type 1 (APS1) or autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED). Here, we report the genomic sequence (18,413 bp) for the entire Aire gene and its 5' flanking region, which contains putative regulatory sequences. Comparison of the genomic and cDNA sequences indicates that the Aire gene is composed of 14 exons and the coding sequence shares high similarities between mouse and human. The sizes of the homologous introns in the two species are conserved; however, the introns do not share significant sequence homologies except the sequences near the splice donor and acceptor sites. Sequence analyses of the 5' regulatory region and the complete coding region in three mouse strains (B6, NOD and SJL) did not reveal any sequence variation, suggesting sequence conservation between different inbred mouse strains. Using one of the six microsatellite markers identified by genomic sequencing and a B6 x Cast backcross mapping panel, we mapped the mouse Aire gene to chromosome 10, a syntenic region containing the Cdl18 and Pfkl genes on human chromosome 21q22.

Animals↗

PubMed1998

Induction of prostate tumor-specific CD8+ cytotoxic T-lymphocytes in vitro using antigen-presenting cells pulsed with prostatic acid phosphatase peptide.

BACKGROUND: Most strategies in cancer immunotherapy are aimed at the induction of a strong cellular immune response against the tumor. Particularly, CD8+ T lymphocytes have been proven in multiple animal models to be critical for the eradication of solid tumors. METHODS: We used a population of peripheral blood-derived antigen-presenting cells (APC), containing dendritic cells (DC), to generate prostate tumor-specific CD8+ T cells. Selected peptides from prostatic acid phosphatase (PAP), a prostate tissue-specific antigen, were shown to bind HLA-A2. A high-affinity peptide was used to generate peptide-specific CD8+ cytolytic T lymphocytes (CTL) from the peripheral blood of healthy donors. RESULTS: The obtained PAP-peptide-specific CTL lysed peptide-coated target cells, vaccinia-infected target cells, and HLA-A2-positive prostate-tumor cells in vitro in an antigen-specific manner. CONCLUSIONS: Our results indicate that CTL precursors to the PAP gene product exist and could be potentially recruited to elicit an antitumor response. Thus, PAP is a suitable antigen for inclusion in prostate cancer vaccines.

Acid Phosphatase↗

PubMed1998

Characterization of mutations in patients with autoimmune polyglandular syndrome type 1 (APS1).

Autoimmune polyglandular syndrome type 1 (APS1), also known as autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), is an autosomal recessive disorder characterized by the failure of several endocrine glands as well as nonendocrine organs. The autoimmune regulator (AIRE) gene responsible for APS1 on chromosome 21q22.3 has recently been identified. Here, we have characterized mutations in the AIRE gene by direct DNA sequencing in 16 unrelated APS1 families ascertained mainly from the USA. Our analyses identified four different mutations (a 13-bp deletion, a 2-bp insertion, one nonsense mutation, and one potential splice/donor site mutation) that are likely to be pathogenic. Fifty-six percent (9/16) of the patients contained at least one copy of a 13-bp deletion (1094-1106del) in exon 8 (seven homozygotes and two compound heterozygotes). A nonsense mutation (R257X) in exon 6 was also found in 31.3% (5/16) of the USA patients. These data are important for genetic diagnosis and counseling for families with autoimmune endocrine syndromes.

Female↗

PubMed1996

Protein turnover in the hypertrophying kidney.

To establish whether altered proteolysis contributes to the increase in protein content in hypertrophying kidneys, we studied protein turnover in proximal renal tubules isolated from rats with three forms of renal hypertrophy, diabetes mellitus (DM), ammonium chloride-induced acidosis and compensatory renal growth (CRG). We found that in DM and in chronic acidosis the normal balance in protein turnover is altered due to attenuated proteolysis and accelerated protein synthesis. Together this favors an increase in kidney protein content. In contrast, in CRG, the increase in protein content is entirely due to increased protein synthesis. Thus, the changes in protein turnover leading to the net gain in kidney protein content in renal hypertrophy depends on the cause of hypertrophy.

Acidosis↗

PubMed1996

The effect of a chocolate bar supplementation on moderate exercise recovery of recreational runners.

To study the effects of a chocolate bar supplementation before exercise on improving recovery of physiological and metabolic changes induced by exercise, 16 male students aged 18-20 years voluntarily served as subjects. A crossover design was employed. Each subject took part in two trials and ran an hour on a treadmill with the intensity of keeping heart rate at 148-150 min for each trial. Results showed that plasma glucose levels of subjects increased significantly (5.42 +/- 0.83 mmol/L) at 15 min after ingestion of a chocolate bar and maintained in moderate high levels (4.92 +/- 0.57 mmol/L) until 30 min after an hour's running while the glucose levels were low and dropped to under normal ranges (3.84 +/- 0.31 mmol/L) at 30 min after exercise as they were with a supplement of placebo. Results of plasma FFA, blood lactate and plasma urea nitrogen levels and RPE all indicated that chocolate bar supplementation before exercise benefits to create the necessary prerequisite for exercise and recovery.

Adolescent↗

PubMed1994

Renal tubular cell protein breakdown in uninephrectomized and ammonium chloride-loaded rats.

Kidney enlargement after unilateral nephrectomy or the induction of a systemic acidosis with ammonium chloride is associated with an increase in kidney protein content. This reflects an imbalance between protein breakdown and protein synthesis. Because it has been shown in diabetic nephromegaly that depressed protein breakdown contributes to the increase in kidney protein content, this study examined whether altered protein breakdown is common to all forms of renal hypertrophy. Accordingly, protein turnover was measured in isolated proximal tubules from kidney in rats undergoing renal enlargement after uninephrectomy or chronic ammonium chloride-induced acidosis. In both conditions, kidney protein content and protein synthesis ([14C]valine incorporation) increased significantly. Fractional protein degradation was depressed in renal tubules isolated from the acidotic rats and was accompanied by a decrease in proximal tubule cathepsin B and combined B and L activities. These changes are comparable to earlier observations with the diabetic kidney. In contrast, after unilateral nephrectomy, protein breakdown is not reduced, and it can reasonably be concluded that, in this condition, protein gain reflects increased protein synthesis alone. It was concluded that the pattern of protein turnover leading to protein accretion in renal hypertrophy varies according to the initial stimulus for renal growth.

Adaptation, Physiological↗

PubMed1991

Amino acids regulate kidney cell protein breakdown.

Amino acids inhibit breakdown of long-lived intracellular proteins in some but not all tissues studied. Because no information is available relating to the effect of amino acids on kidney cell proteolysis, this study was conducted with cultured proximal-like opossum kidney (OK) cells and primary cultured rabbit proximal tubular cells in which long-lived cell proteins were labeled with carbon 14-labeled valine. These cultured cells were acutely deprived of amino acids; this was followed by a 57% to 66% increase in the proteolytic rate in OK cells and a 22% rate increase in the rabbit kidney cells. In cultured OK cells incubated in serum-free minimal essential medium containing 13 amino acids, proteolysis averaged 4.62% +/- 0.28%/2 hr and increased to 7.66% +/- 0.38%/2 hr when amino acids were deleted. Each amino acid was then added alone. Leucine, phenylalanine, and lysine had significant effects in inhibiting the deprivation response by 40%, 26%, and 22%, respectively. Leucine appears to inhibit proteolysis directly and not through its metabolites, since alpha-ketoisocaproate, the leucine transamination product, was without effect. Similarly, failure of tyrosine to inhibit proteolysis suggests a direct phenylalanine action. When leucine, phenylalanine, and lysine were simultaneously deleted from the incubation medium, the increase in proteolysis corresponded to 56% of the response after deletion of all amino acids. Thus to maximally affect proteolysis, amino acids, which on their own have little effect on protein breakdown, also appear to play a role. From this study we conclude that amino acids seem to play an important and direct role in the regulation of kidney epithelial cell protein breakdown.

Amino Acids↗

PubMed1990

Modulation of kidney cell protein degradation by insulin.

Insulin is an established regulator of intracellular proteolysis in several mammalian tissues but little is known about its role in the kidney. The present study was undertaken to determine whether insulin influences protein degradation in isolated rat renal proximal tubules and to investigate its mechanism of action in cultured proximal-like tubular epithelial cells from the opossum kidney. Long-lived protein degradation was determined from the release of carbon 14-labeled valine from previously labeled cellular protein under conditions designed to minimize label reutilization. In isolated tubules, the mean control rate of proteolysis was 2.18% per hour, indicating an appreciable turnover of cellular protein. Insulin (10(-6) mol/L) decreased the rate by 23%. In cultured kidney cells, the rate of protein degradation averaged 1.25% per hour in the presence of serum and 1.68% per hour in its absence, an increase of 34%. High insulin concentrations suppressed this acceleration completely, and physiologic levels inhibited it partially. No evidence was obtained to indicate that insulin action is mediated through stimulation of Na(+)-H+ antiport or through increased amino acid utilization. Ammonium chloride, however, strongly attenuated the serum deprivation response and the inhibitory effect of insulin. The exact mechanisms whereby insulin inhibits proteolysis is not known, but these findings are consistent with an inhibitory action of insulin on the lysosomal pathway.

Ammonium Chloride↗