Receptor-effector coupling by G proteins: implications for normal and abnormal signal transduction.
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Amino Acid Sequence↗
Biomedical subjects
L S Weinstein
Publications and source records attributed to L S Weinstein.
Studies in a kindred with parathyroid carcinoma.
We report a family with primary hyperparathyroidism in four patients in two generations with apparent autosomal dominant transmission. A fifth member was probably affected. Two cases had definite parathyroid carcinoma (PC), and two had parathyroid adenoma with atypical features that could represent an early stage of cancer. In each of our patients, one parathyroid gland was abnormal. Five other parathyroid glands (in two patients) were normal in histology and size. There was no evidence of neoplasia in other tissues. Constitutional karyotypes were normal in all four patients. We identified three chromosomal abnormalities (a reciprocal translocation between chromosomes 3 and 4, trisomy 7, and a pericentric inversion in chromosome 9) in cultured PC tissue from one patient. These chromosomal changes are of unclear significance. Analyses on tumor DNA from one case of PC and one of atypical adenoma showed no evidence of ras gene mutations, PTH gene rearrangement, or allelic loss from chromosome 11q13 (locus of the gene for multiple endocrine neoplasia type 1). This family shows susceptibility to cancer without antecedent hyperplasia in all parathyroids. It could help identify a novel tumor susceptibility gene.
Adenoma↗
Linear gastrectomy: an endoscopic staple-assisted anterior highly selective vagotomy combined with posterior truncal vagotomy for treatment of peptic ulcer disease.
A technique of anterior highly selective vagotomy is described that uses an endoscopic stapling device to facilitate and speed the procedure. Further study is necessary to ascertain the long-term recurrence rate for this new procedure, but it shows great promise as a simplified procedure for laparoscopic application in peptic ulcer disease.
Female↗
Activating mutations of the stimulatory G protein in the McCune-Albright syndrome.
BACKGROUND: The McCune-Albright syndrome is a sporadic disease characterized by polyostotic fibrous dysplasia, café au lait spots, sexual precocity, and hyperfunction of multiple endocrine glands. These manifestations may be explained by a somatic mutation in affected tissues that results in activation of the signal-transduction pathway generating cyclic AMP (cAMP). We analyzed DNA from tissues of patients with the McCune-Albright syndrome for the presence of activating mutations of the gene for the alpha subunit of the G protein (Gs alpha) that stimulates cAMP formation. METHODS: Genomic DNA fragments encompassing regions (exons 8 and 9) previously found to contain activating missense mutations of the Gs alpha gene (gsp mutations) in sporadically occurring pituitary tumors were amplified in tissues from four patients with the McCune-Albright syndrome by the polymerase chain reaction. The amplified DNA was analyzed for mutations by denaturing gradient gel electrophoresis and allele-specific oligonucleotide hybridization. RESULTS: We detected one of two activating mutations within exon 8 of the Gs alpha gene in tissues from all four patients, including affected endocrine organs (gonads, adrenal glands, thyroid, and pituitary) and tissues not classically involved in the McCune-Albright syndrome. In two of the patients, histidine was substituted for arginine at position 201 of Gs alpha, and in the other two patients cysteine was substituted for the same arginine residue. In each patient the proportion of cells affected varied from tissue to tissue. In two endocrine organs, the highest proportion of mutant alleles was found in regions of abnormal cell proliferation. CONCLUSIONS: Mutations within exon 8 of the Gs alpha gene that result in increased activity of the Gs protein and increased cAMP formation are present in various tissues of patients with the McCune-Albright syndrome. Somatic mutation of this gene early in embryogenesis could result in the mosaic population of normal and mutant-bearing tissues that may underlie the clinical manifestations of this disease.
Adolescent↗
The role of G-protein in matrix-mediated motility of highly and poorly invasive melanoma cells.
Membranes from 2 K1735 murine melanoma clones of high invasive capacity show increased amounts of pertussis toxin (PT) substrate when compared to a weakly invasive cellular counterpart. Using a panel of specific G-protein antibodies, we identified Gi alpha 2 as the PT-sensitive G-protein uniquely abundant in highly invasive cells. In addition, RNA hybridization results confirm the immunoblot observations that Gi alpha 2 is present at higher levels in strongly invasive cells. This result suggests that the elevated expression of Gi alpha 2 in highly invasive cells is not entirely due to differences in either translational efficiency or protein degradation but is related to altered RNA transcriptional initiation, processing and/or degradation. ADP-ribosylation of Gi alpha-subunits by PT inhibited the fibronectin, laminin and collagen type-IV-stimulated motility of the 2 highly invasive clones, while PT treatment of cells from a poorly invasive clone resulted in little or no reduction of the fibronectin, laminin or collagen type-IV-stimulated lower motility. Furthermore, PT treatment of highly or poorly invasive K1735 clones does not result in any alteration in cellular cAMP accumulation, suggesting that the PT substrate is not linked with the adenylyl cyclase enzyme complex. The data suggest that a PT-sensitive G-protein, probably Gi alpha 2 regulates second messenger pathways that contribute to elevated motility in highly invasive K1735 cells.
Adenylate Cyclase Toxin↗
Genetic mapping of the Gs-alpha subunit gene (GNAS1) to the distal long arm of chromosome 20 using a polymorphism detected by denaturing gradient gel electrophoresis.
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Base Sequence↗
Locally recurrent parathyroid neoplasms as a cause for recurrent and persistent primary hyperparathyroidism.
Between 1982 and 1989, 145 patients underwent operations for persistent or recurrent primary hyperparathyroidism (HPT). At re-exploration, 15 patients (10.3%) were found to have locally recurrent parathyroid tumors (11 patients with adenoma and 4 with carcinoma). These 15 patients had 28 previous operations at outside institutions for HPT. Patients with locally recurrent HPT secondary to adenoma had a longer disease-free interval than patients with locally recurrent carcinoma. At the time of evaluation at the National Institutes of Health (NIH) for recurrent or persistent HPT, each patient was symptomatic and patients with carcinoma had significantly more symptoms and higher serum levels of calcium and parathyroid hormone than patients with adenoma. Locally recurrent parathyroid neoplasm was correctly localized by preoperative testing in 14 of 15 patients. These 15 patients underwent 18 reoperations at NIH for excision of locally recurrent parathyroid tumors. Following the final reoperation (two patients had more than one procedure), each patient had normal serum levels of calcium. In addition each patient remains biochemically cured (based on normal serum calcium level), with a median follow-up interval of 21 months. Local recurrence of parathyroid adenoma comprises a small but significant proportion of cases of recurrent or persistent HPT and can be indistinguishable from parathyroid carcinoma. Findings suggestive of carcinoma include shorter disease-free interval, higher serum levels of calcium and parathyroid hormone, and histologic appearance. Whether the locally recurrent parathyroid neoplasm is benign or malignant, aggressive surgery can control serum levels of calcium in these patients with acceptable rates of morbidity.
Adenoma↗
Mutations of the Gs alpha-subunit gene in Albright hereditary osteodystrophy detected by denaturing gradient gel electrophoresis.
Affected members of most kindreds with Albright hereditary osteodystrophy have a partial deficiency of functional Gs, the guanine nucleotide-binding protein that stimulates adenylyl cyclase. By use of the polymerase chain reaction to amplify genomic fragments with the attachment of a high-melting G + C-rich region (GC clamp) and analysis of these fragments by denaturing gradient gel electrophoresis, heterozygous mutations in the Gs alpha-subunit gene were found in two kindreds. These included a G----C substitution at the donor splice junction of intron 10 and a coding frameshift created by a single base deletion within exon 10. The findings illustrate the heterogeneity of genetic defects in Albright hereditary osteodystrophy and the usefulness of the polymerase chain reaction-denaturing gradient gel electrophoresis method to search rapidly for mutations in a large candidate gene.
Amino Acid Sequence↗
Characterization of the promoter of the human Gi2 alpha-subunit gene.
The promoter of the human gene for the alpha-subunit of Gi2, a GTP-binding signal transduction protein, was analyzed by cloning the 5' flanking region of the gene upstream of the bacterial chloramphenicol acetyltransferase (CAT) gene and measuring the level of CAT expression after transfection in CV-1 green monkey kidney cells. Analysis of multiple 5' deletion mutants reveals that a minimum of 85 bases upstream of the major transcriptional initiation site are required for full basal promoter activity. Deleting 11 bases to position -74 causes a 4-fold decrease in promoter activity. Another major decrement in activity is seen when a GC box between -46 and -33 is deleted, consistent with this region being a functionally active Sp1 factor-binding site. Primer extension of a CAT-specific primer hybridized to RNA from cells transfected with a Gi2 alpha promoter-CAT construct confirms approximately the same transcriptional start site as the endogenous Gi2 alpha gene. The 3' deletion mutants that either approach or delete the transcriptional start site have markedly diminished activity.
Animals↗
Laparoscopic cholecystectomy.
Laparoscopic cholecystectomy is a new method of removing diseased gallbladders. It has the advantage of being an outpatient procedure with rapid full recovery. Morbidity and complications are decreased, and patient satisfaction has been excellent. This is a report of our first 42 patients selected to undergo this procedure.
Adult↗
Clonality of parathyroid tumors in familial multiple endocrine neoplasia type 1.
Familial multiple endocrine neoplasia type 1 (MEN-1) is characterized by tumors of the parathyroids, endocrine pancreas, and anterior pituitary. Since the gene associated with MEN-1, located on chromosome 11 (11q13), may normally inhibit tumor proliferation, tumors could arise from inactivation of one or both of the alleles. However, parathyroid tumors in patients with MEN-1 have been considered to result from polyclonal hyperplasia. Using genetic probes, we tested parathyroid tumors for a monoclonal component, represented by a loss of alleles at any of eight loci along chromosome 11. Ten of 16 tumors from 14 patients with familial MEN-1 had losses of alleles from chromosome 11. Tumors with losses were larger than those without (1.6 vs. 0.2 g; P less than 0.002), suggesting that a monoclonal adenoma may develop after a phase of polyclonal hyperplasia. In 7 of 10 tumors, the subregion of loss was less than the full length of chromosome 11 but always included one copy of the MEN-1 locus. Of 34 sporadic adenomas from patients without MEN-1, 9 showed similar allelic losses in chromosome 11; in 7 the losses included the apparent MEN-1 locus. We conclude that many "hyperplastic" parathyroid tumors in familial MEN-1 are in fact monoclonal and may progress or even begin to develop by inactivation of the MEN-1 gene (at 11q13) in a precursor cell. Some sporadic adenomas have allelic losses on chromosome 11, which may also involve the MEN-1 gene.
Adenoma↗
Cloning and characterization of the human gene for the alpha-subunit of Gi2, a GTP-binding signal transduction protein.
We isolated and characterized human genomic clones encompassing the gene for the alpha-subunit of Gi2, a GTP-binding signal transduction protein abundantly expressed in myeloid cells. The gene is divided into 9 exons and spans 23.5 kb. Exons 2, 6 and 7 encode putative guanine nucleotide-binding domains that are highly conserved among GTP-binding proteins. A polyadenylation signal located within exon 9 predicts an mRNA size (approximately 2.3 kb) several hundred bases longer than that of published cDNAs, and consistent with the size seen on RNA blot hybridization. Primer extension and S1 nuclease analysis determined a major and several minor transcriptional start sites. The first exon and 5' flanking region are highly G + C rich, contain several GC boxes (SP1 transcription factor binding sites), a CAAT box, and lack a TATA box. The presumptive promoter region is thus similar to that of ras and other widely expressed genes.
Amino Acid Sequence↗
Effects of teleocidin and the phorbol ester tumor promoters on cell transformation, differentiation, and phospholipid metabolism.
The potent tumor-promoting agent 12-O-tetradecanoylphorbol-13-acetate (TPA) and related diterpene phorbol esters have been shown to enhance viral transformation and anchorage-independent growth, inhibit differentiation, and stimulate phosphatidylcholine turnover in various cell culture systems. In the present study, we report that teleocidin, and indole alkaloid isolated from Streptomyces, induces several biological effects similar to those of TPA in cell culture. Both TPA and teleocidin enhanced transformation of a clone of Fischer rat embryo cells (CREF) by a temperature-sensitive mutant of adenovirus type 5 (H5ts125); enhanced the cloning efficiency in agar of E11 cells, a clone of H5ts125-transformed Sprague-Dawley rat embryo cells; inhibited melanogenesis in murine B-16 melanoma cells; inhibited myogenesis in myoblast cultures established from normal human skeletal muscle; and stimulated choline release from prelabeled phospholipids of C3H10T 1/2 mouse cells. In general, TPA and teleocidin were equipotent in inducing these biological effects and were most active in the 3- to 10-ng/ml range, i.e., approximately 10(-8) to 10(-9) M. These studies provide further evidence that teleocidin represents a new class of tumor-promoting agents with properties similar to, if not identical with, those of the phorbol ester tumor promoters. These findings also suggest that cell culture systems can be used to identify new types of tumor-promoting agents in addition to the diterpene phorbol esters.
Adenoviruses, Human↗