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PubMed1994

Deletion variants of L-hydroxyisocaproate dehydrogenase. Probing substrate specificity.

The substrate specificity and catalytic activity of the dinucleotide-dependent L-2-hydroxyisocaproate dehydrogenase from Lactobacillus confusus (L-HicDH) have been altered by modifying an enzyme region which is assumed to be involved in substrate recognition. The design of the variant enzymes was based on an amino acid alignment of the modified region with the functionally related L-lactate dehydrogenases. The best absolute sequence similarity for a protein with known tertiary structure was found for L-lactate dehydrogenase from dogfish (23%). In this study, the coenzyme loop, a functional element which is essential for catalysis and substrate specificity, was modified in order to identify the residues involved in the catalytic reaction and observe the effect on the substrate specificity. Deletions were introduced into the L-hydroxyisocaproate gene by site-directed mutagenesis. Several deletion-variant enzymes Ile100A delta, Lys100B delta, Leu101 delta, Asn105A delta and Pro105B delta showed an altered substrate specificity. For the variant enzyme with the deletion of Asn/Pro105A/B, 2-oxo carboxylic acids branched at C4 proved to be better substrates than 2-oxocaproate, the substrate with the best kcat/KM ratio known for the wild-type enzyme. The mutation resulted in a 5.2-fold increased catalytic efficiency towards 2-oxoisocaproate compared to the wild-type enzyme. After deleting Ile/Lys100A/B, 2-phenylpyruvate is the only substrate which is still converted at a significant catalytic rate. The kcat ratios of 2-oxocaproate versus 2-phenylpyruvate changed by a factor of 6500 when comparing wild-type enzyme and deletion-variant enzyme data. The single amino acid deletions in position 100A and 100B caused drastic reductions in the catalytic activity for all tested substrates, whereas the deletion of Lys100B, Leu101, Asn105A as well as Pro105B showed more specific modifications in catalytic rates and substrate recognition for each tested substrate.

Alcohol Oxidoreductases↗
PubMed1996

An alternative splice variant of human IL-4, IL-4 delta 2, inhibits IL-4-stimulated T cell proliferation.

Alternative splicing of mRNA can generate protein isoforms that are preferentially expressed in different tissues or during different states of cell differentiation or activation. Protein isoforms may have different functions. In this study, we cloned, expressed, and tested functional effects of a naturally occurring splice variant of human IL-4, called IL-4 delta 2. In IL-4 delta 2, the second exon of IL-4 is omitted by alternative splicing, with exons 1, 3, and 4 joined in an open reading frame. We found that IL-4 delta 2 RNA is expressed in the PBMC of all donors tested, usually in lower amounts than IL-4 RNA. In contrast, IL-4 delta 2 RNA is expressed in much higher levels than IL-4 RNA in thymocytes and bronchoalveolar lavage cells, suggesting tissue specificity of expression. IL-4 delta 2 cDNA was expressed in yeast. Recombinant human (rh) IL-4 delta 2 was partially purified and found to be glycosylated, with a protein core of 13 to 15 kDa. Unlike rhIL-4, rhIL-4 delta 2 did not act as a costimulator for T cell proliferation. However, rhIL-4 delta 2 inhibited the ability of rhIL-4 to act as a T cell costimulator. Inhibition was independent of glycosylation and was not mediated by toxicity. Iodinated IL-4 delta 2 was found to bind specifically to human PBMC and tumor lines known to express IL-4 receptors. Excess unlabeled IL-4 inhibited cellular binding of labeled IL-4 delta 2. Thus, rhIL-4 delta 2 is a naturally occurring splice variant of IL-4 that is preferentially expressed in the thymus and airways and inhibits function of complete IL-4. The balance between IL-4 and IL-4 delta 2 may be important in the regulation of IL-4 effects.

Amino Acid Sequence↗
PubMed1991

[Chronic hepatitis delta--the course and approaches to therapy].

Variants of chronic hepatitis delta (CHD) course were studied in 94 patients. Slow progress (for decades) occurred most frequently, while rapid progress to hepatic cirrhosis (for 1-2 years) or benign course presenting as greater than 3-year remission were rare findings. In addition to routine therapeutic modalities, except corticosteroids, 43 CHD patients received recombinant alpha 2-interferon (reaferon). Follow-up results evaluated separately for hepatic cirrhosis and free of it CHD patients support clinical promise of Soviet recombinant alpha 2-interferon against CHD.

Adolescent↗
PubMed1997

Association between a delta opioid receptor gene polymorphism and heroin dependence in man.

Two allelic variants of the delta opioid receptor gene, distinguished by a single base exchange T to C in codon 307 of the translated region, were detected in humans. The amino acid sequence was thereby not changed. The resulting C and T alleles combined to give the three genotypes CC, CT and TT. Allele C was more frequent in a sample of 103 German Caucasian heroin addicts (53.4%) than in a control group (39.1%, n = 115). The proportion of CC homozygotes was much greater among the drug-dependent subjects (26.2%) than in controls (9.6%). Although the reasons for this association remain to be explained, our results argue for a participation of the delta type of opioid receptors in the pathophysiology of heroin dependence.

Alleles↗
PubMed1993

New isoforms of multifunctional calcium/calmodulin-dependent protein kinase II.

Calcium/calmodulin dependent protein kinase II (CaM kinase II) seems to act as an important regulator of intracellular signal transmission. Four subtypes, termed alpha to delta, have been cloned; some of them can exist as different splicing variants. All these isoforms share a great overall homology, and they contain 3 areas of low homology. We have identified 5 new variants of subtype delta so that the total number of different isoforms now adds up to 12. These variants are probably a result of different splicing and show several deletions in regard to subtype delta. The deletion sites do exactly match regions of low homology between the subtypes. This suggests a functional division of the CaM kinase II molecule into homologous and variable domains. The homologous domains are highly conserved. Therefore, it might be the case that the constitution of the variable domains is more significant for a certain isoform than its belonging to one of the 4 subtypes alpha to delta.

Alternative Splicing↗
PubMed1978

Hemoglobin Lincoln Park: a betadelta fusion (anti-Lepore) variant with an amino acid deletion in the delta chain-derived segment.

An electrophoretically slow-moving hemoglobin variant was identified in three members of a family originating from Southern Mexico. The variant, Hb Lincoln Park, made up approximately 14% of the total hemoglobin and appeared to have normal stability and functional properties. None of the individuals in whom the abnormal hemoglobin was present was anemic, but each had a mildly elevated reticulocyte count. Structural data suggest that the non-alpha chain of Hb Lincoln Park represents a betadelta gene-fusion product, with normal beta chain structure of the amino-terminal portion of the chain and delta sequences subsequently, the crossover point occurring between animo acid residues 22 and 50. An additional abnormality is the deletion of valine-137, a component of the delta gene-derived segment of the betadelta chain. To account for the development of this abnormal globin chain, a series of intergenic crossovers is proposed; the first, a nonhomologous crossover between the beta and delta genes, presumably gave rise to the betadelta fusion gene; two additional crossovers, one of them unequal, may then have occurred between the same beta and delta genes to produce the amino acid deletion.

Adult↗
PubMed1995

Protein thermal denaturation, side-chain models, and evolution: amino acid substitutions at a conserved helix-helix interface.

Random mutant libraries with substitutions at the interface between the N- and C-terminal helices of Saccharomyces cerevisiae iso-1-cytochrome c were screened. All residue combinations that have been identified in naturally occurring cytochrome c sequences are found in the libraries. Mutants with these combinations are biologically functional. Enthalpies, heat capacities, and midpoint temperatures of denaturation are used to determine the entropy and Gibbs free energy of denaturation (delta GD) for the ferri form of the wild-type protein and 13 interface variants. Changes in delta GD cannot be allocated solely to enthalpic or entropic effects, but there is no evidence of enthalpy-entropy compensation. The lack of additivity of delta GD values for single versus multiple amino acid substitutions indicates that the helices interact thermodynamically. Changes in delta GD are not in accord with helix propensities, indicating that interactions between the helices and the rest of the protein outweigh helix propensity. Comparison of delta GD values for the interface variants and nearly 90 non-cytochrome c variants to side-chain model data leads to several conclusions. First, hydrocarbon side chains react to burial-like transfer from water to cyclohexane, but even weakly polar side chains respond differently. Second, despite octanol being a poor model for protein interiors, octanol-to-water transfer free energies are useful stability predictors for changing large hydrocarbon side chains to smaller ones. Third, unlike cyclohexane and octanol, the Dayhoff mutation matrix predicts stability changes for a variety of substitutions, even at interacting sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2006

Identification and characterization of four splicing variants of ovine POU1F1 gene.

Expression of POU1F1 gene, a member of the POU homeodomain family of transcription factors, is necessary for normal differentiation, development and survival of three anterior pituitary cell types (thyrotrophs, somatotrophs and lactotrophs) and for the proper expression of growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH) genes and POU1F1 gene itself. Alternative splicing forms of this gene have been reported in different species, with few functional studies. Apart from the POU1F1-Wild-type with the expected length, in this work we isolated three additional splicing variants: POU1F1-beta, with a 78 bp insert in the trans-activation domain; POU1F1-gamma that lacks exon 3 and POU1F1-delta that lacks exons 3, 4 and 5. Four different protein isoforms were also detected by Western blot in the sheep pituitary tissue. Functional assays were performed to study the trans-activation of GH and PRL promoters by the splicing variants. Regarding the PRL promoter, the beta variant presented only 12% of the Wild-type trans-activation capacity. Variants gamma and delta showed no capacity to trans-activate PRL promoter. Both gamma and delta variants acted as repressors of Wt, reducing significantly the trans-activation made by Wt alone (p<0.05). Concerning the GH promoter, the beta variant presented a trans-activation capacity 10% higher than Wt. Wt and beta variants strongly interact in the activation of GH promoter doubling the trans-activation potential of Wt. Variants gamma and delta showed no capacity to trans-activate the GH promoter and both acted as repressors, reducing significantly (p<0.001) the trans-activation performed by Wt. This work presents, for the first time, the characterization of four splicing forms of Ovis aries POU1F1 gene.

Alternative Splicing↗
PubMed1992

Comparison of the galactopoietic response to pituitary-derived and recombinant-derived variants of bovine growth hormone.

Two studies were designed to examine the differences in galactopoietic potency of molecular variants of pituitary- and recombinant-derived bovine GH (bGH). The recombinant bGH molecules included amino-terminal and position-127 amino acid substitutions which are representative of two of the four natural pituitary variants or of partially degraded bGH molecules. Amino-terminal variants of bGH included methionine (Met1), alanine (Ala1), serine (Ser1) or deletion of four amino acids (delta 1-4). The delta 1-4 variants were representative of degradation products previously isolated in pituitary bGH preparations. In the first study, 54 lactating Holstein cows received i.m. injections of a buffer solution (control), pituitary-derived bGH, or recombinant-derived [Met1,Leu127]-bGH, [Met1,Val127]-bGH, [Ala1,Leu127]-bGH, or [Ala1,Val127]-bGH. Cows received 25 mg bGH/day for 21 days. Substitution of the amino-terminal alanyl residue with methionine did not affect milk response. GH variants with Val127 elicited a greater milk response (8.5 kg/day) than Leu127 bGH variants (6.5 kg/day). The average milk response to the four recombinant bGH variants was 7.5 kg/day greater than controls compared with 4.4 kg/day for pituitary-derived bGH. In contrast, blood bGH concentrations were equivalent for pituitary and recombinant bGH treatments, approximately 20 micrograms/l more than control levels at 3 h after injection. Blood free fatty acid concentrations were increased, but insulin and glucose levels were unaffected by bGH treatment. In the second study, 54 lactating Holstein cows received i.m. injections of a buffer control solution or recombinant-derived [Met1,Leu127]-bGH, [Ser1,Leu127]-bGH, [Ser1,Val127]-bGH, [delta 1-4,Leu127]-bGH or [delta 1-4,Val127]-bGH. Cows received 25 mg bGH/day for 28 days. The milk response to full-length bGH variants was 6.6 kg/day greater than the response to the amino-terminal deletion variants (P less than 0.05). Substitution of valine for leucine did not affect milk response to either the deletion (delta 1-4) or full-length (Met1 or Ser1) bGH molecules. In conclusion, the lowered galactopoietic potency of pituitary bGH preparations was demonstrated, at least in part, to be due to the presence of amino-terminal amino acid deletions rather than differences in amino acid sequences of recombinant bGH. Ala1 bGH variants with valine at position 127 elicited a greater milk response than Leu127 variants.

Amino Acid Sequence↗
PubMed1979

Hemoglobin Crete (beta 129 ala leads to pro): a new high-affinity variant interacting with beta o -and delta beta o -thalassemia.

Hemoglobin Crete, beta129 (h7)ala leads to pro, is a new mutant hemoglobin (Hb) with high oxygen affinity that was discovered in a Greek family in various combinations with beta- and deltabeta-thalassemia. The propositus, who presented an unusual clinical picture of an "overcompensated" hemolytic state, with erythrocytosis, splenomegaly, abnormal red cell morphology, and marked erythroid hyperplasia, appeared doubly heterozygous for Hb Crete and deltabeta-thalassemia. His red cells contained 67% Hb Crete and 30% Hb F, and the combination of these two hemoglobins resulted in a blood P50O2 of 11.2 mm Hg. A brother with Hb Crete trait (38% Hb Crete, 56% Hb A, blood P50O2 23.0 mm Hg) did not have significant erythrocytosis. Purified Hb Crete was heat-unstable and exhibited a high oxygen affinity, and a normal Bohr effect. We postulate that the beta 129 proline substitution disrupts the H helix, perturbing nearby residues involved in alpha 1 beta 1 contact sites of the Hb tetramer.

Adult↗
PubMed1995

Tissue-dependent expression of a novel splice variant of the human oestrogen receptor.

We have isolated a novel splice variant of ER mRNA from normal endometrial tissue using RT/PCR. The variant contains an unusual splice junction formed by splicing sequences within exons 4 and 7 together. The translated protein product would be predicted to lack part of exon 4, all of exons 5 and 6 and, due to a missense alignment at the new splice junction, the remaining sequence from exon 7 would be translated out of frame and terminate at the exon 7/8 splice junction. As a result, the protein would lack most of the hormone binding domain (HBD) and the major oestrogen-dependent transactivating region (AF-2), but still contain the DNA binding domain (DNA-BD) and N-terminal transactivating region (AF-1). In contrast to the exon 5 deleted variant of ER (delta 5), which was expressed in both normal endometrium and liver, this novel variant was present in endometrium but not in liver samples. These results confirm that some ER splice variants are expressed in normal, non-malignant oestrogen responsive tissues. In addition, they demonstrate the tissue specific expression of a novel and interesting splice variant of ER in these normal tissues.

Alternative Splicing↗
PubMed1984

Interaction of Vicia graminea anti-N lectin with cell surface glycoproteins from erythrocytes with rare blood group antigens.

The erythrocyte receptors for Vicia graminea (Vg) anti-N lectin have been investigated after 125I-labelling of the purified lectin and binding to membrane components separated by dodecyl sulphate polyacrylamide gel electrophoresis. GP alpha (synonym glycophorin A or MN glycoprotein) and GP delta (synonym glycophorin B or Ss glycoprotein) are the main Vg receptors of native human blood group NN and MN erythrocytes whereas Vg lectin only binds to GP delta from MM red cells. The glycoprotein of 28 kDa present in Mi III erythrocytes (a presumed variant of GP delta) carries Vg receptors. Both binding studies and agglutination experiments with this lectin suggest that the delta Mi III gene might produce more glycoprotein molecules than the normal delta gene. Binding of Vg lectin to hybrid glycoproteins [from Mi V, St(a+) and Dantu (+) donors] produced by unequal crossing-over between alpha and delta genes, may occur if the molecules exhibit N activity. The lectin does not bind to sialic acid- and galactose-deficient glycoproteins from Tn erythrocytes and no binding could be detected in the region of GP delta of erythrocytes from S-s-U-individuals. Addition of N-acetylgalactosamine residues to the alkali-labile oligosaccharides attached to GP alpha and GP delta, as found in Cad erythrocytes, decrease the binding capacity for Vg lectin. Finally the absence of Vg lectin binding sites on native GP alpha molecule from MgMg and McM erythrocytes, which carry well defined variants of this glycoprotein, supports the view that the binding site of the lectin on native glycoproteins is located at the N-terminal end of glycoprotein (GP alpha and GP delta) with N specificity (N-terminus = Leu).

Antigens, Surface↗
PubMed1995

A polymorphism in the delta-aminolevulinic acid dehydratase gene may modify the pharmacokinetics and toxicity of lead.

Associations between the presence of a constitutional variant of delta-aminolevulinic acid dehydratase (ALAD-2) and lead concentrations in blood and bone, as well as between this allele and indices of kidney function, were investigated among 691 members of a construction trade union. The average blood lead level in this group was 7.78 micrograms/dl. No significant difference was observed in blood lead concentration in ALAD-2 carriers compared to those homozygous for the more common ALAD-1 allele (7.78 +/- 3.62 micrograms Pb/dl vs. 7.73 ( +/- 3.48 micrograms Pb/dl, respectively; p = 0.73). Bone lead was measured in a subset of 122 of the study subjects. Patella minus tibia lead concentrations for each individual averaged 3.35 +/- 11.99 micrograms Pb/g bone mineral in ALAD-1 homozygotes and 8.62 +/- 9.47 micrograms Pb/g bone mineral in ALAD-2 carriers (p = 0.06). Comparisons of blood urea nitrogen (BUN) and uric acid by genotype indicated elevated levels among ALAD-2 individuals (p = 0.03 and 0.07, respectively). In logistic regression models accounting for other variables potentially associated with BUN and uric acid levels, BUN was significantly associated with blood lead levels (p = 0.01). Associations of BUN and uric acid levels with ALAD-2 were of borderline statistical significance in these models (p = 0.06 and 0.07). Taken together, these results suggest that the ALAD-2 genotype may influence the pharmacokinetic distribution and chronic renal toxicity of lead, perhaps due to differential binding of lead to the variant protein.

Adult↗
PubMed1979

DNA sequence variants in the G gamma-, A gamma-, delta- and beta-globin genes of man.

DNA prepared from 60 unrelated individuals was cleaved with one of eight different restriction endonucleases and the resulting DNA fragments were separated by agarose gel electrophoresis. DNA fragments containing G gamma-, A gamma-, delta- or beta-globin genes were detected by Southern blot hybridization, using as probe either a 32P-labeled cloned DNA copy of rabbit beta-globin messenger RNA or labeled human beta- and G gamma- globin cDNA plasmids. Three types of variant restriction enzyme patterns of globin DNA fragments were detected in otherwise normal individuals. One variant pattern, found in only one person, was caused by an additional restriction endonuclease Pst I cleavage site in the center of the delta- globin gene intervening sequence; the subject was heterozygous for the presence of this cleavage site and was shown to have inherited it from her mother. Another variant pattern resulted from the appearance of an endonuclease Hind III cleavage site in the intervening sequence of the A gamma-globin gene; this variant is polymorphic, with a gene frequency for the presence of the intragenic Hind III site of 0.23. This Hind III cleavage site polymorphism is also found in the G gamma-globin gene intervening sequence and thus the polymorphism itself appears to be duplicated over the pair of gamma-globin loci. These variants can be used to derive an approximate estimate of the total number of different DNA sequence variants in man.

Base Sequence↗
PubMed1993

Identification of novel isoforms of the delta subunit of Ca2+/calmodulin-dependent protein kinase II. Differential expression in rat brain and aorta.

Two novel isoforms of the Ca2+/calmodulin-dependent protein kinase II delta subunit were detected in rat aorta. Identification of the subunits was based on two independent lines of evidence, i.e. detection by immunoblotting of differently sized delta subunits and DNA sequence analysis of partial cDNA clones of the kinase. Cytosolic extracts from rat brain, aorta, and cultured aortic cells were analyzed by Western blotting using a delta subunit-specific antipeptide antibody. Aortic extracts demonstrated a single 53-kDa cross-reactive band approximately 7 kDa smaller than the cross-reactive band seen in brain. To ascertain the structural basis for this difference, reverse-transcribed RNAs from rat aorta and brain were analyzed by polymerase chain reaction (PCR), and the PCR fragments were cloned and sequenced. When aortic cDNA was analyzed with a primer pair that spanned the known variable region of the brain kinase subunit, the amplified PCR products were smaller than the major product obtained from brain cDNA. The aortic PCR product was cloned and sequenced and found to represent two novel subunit sequences, designated delta 2 and delta 3 to distinguish them from the previously described delta sequence (now called delta 1) from brain. delta 2 was identical to the predicted delta 1 sequence except for a deletion of 102 base pairs (bp). This deletion corresponded to nearly the entire variable domain. In the sequence of delta 3, this 102-bp region was replaced by a sequence of 33 bp that had 79% nucleotide sequence identity to a portion of the gamma subunit variable domain. A fourth form of the delta subunit (delta 4) was identified in rat skeletal muscle. The delta 4 isoform was characterized by the deletion of a 42-bp sequence identical to the 42 bp at the 3' end of the 102-bp deletion of delta 2. Reverse-transcription PCR analysis of additional rat tissues indicated that alternatively spliced variants of the delta subunit of Ca2+/calmodulin-dependent protein kinase II are expressed in a tissue-specific pattern.

Amino Acid Sequence↗
PubMed1993

Molecular analysis of G6PD variants in northern Italy: a study on the population from the Ferrara district.

In the Ferrara district, an area south of the Po delta, four different variants of glucose-6-phosphate dehydrogenase (G6PD;E.C.1.1.49) have been described as a result of biochemical characterization of the enzyme protein: one was G6PD Mediterranean (G6PD Med) and three were local variants named Ferrara I, II, and III. The Ferrara I variant was recently analysed at the DNA level and shown to correspond to G6PD A376G/202A, while the mutations causing the variants II and III, still remain unknown. We analysed the G6PD coding region of 18 apparently unrelated G6PD deficient subjects, whose families have lived in the Ferrara district for at least three generations: 12 subjects had G6PD Med563T/1311T, 3, G6PD Santamaria376G/542T and 2, G6PD A-376G/202A. In one subject we found a new mutation, a G-->A transition at nucleotide 242 causing an Arg-->His amino-acid replacement at position 81. We named this new variant G6PD Lagosanto242 A. Phenotypically the enzyme has nearly normal kinetic properties and appears different from the variants Ferrara II and III.

Child↗
PubMed2001

The delta-aminolevulinic acid dehydratase (ALAD) polymorphism and bone and blood lead levels in community-exposed men: the Normative Aging Study.

Recent research has indicated that a polymorphic variant of delta-aminolevulinic acid dehydratase (ALAD) may influence an individual's level of lead in bone and blood and, as a result, may also influence an individual's susceptibility to lead toxicity. In this study, we investigated whether this ALAD polymorphism is associated with altered levels of lead in bone and blood among 726 middle-aged and elderly men who had community (nonoccupational) exposures to lead. We measured levels of blood and bone lead by graphite furnace atomic absorption spectroscopy and a K X-ray fluorescence (KXRF) instrument, respectively. We determined the ALAD MspI polymorphism in exon 4 by a polymerase chain reaction restriction fragment length polymorphism (RFLP). Of the 726 subjects, 7 (1%) and 111 (15%) were, respectively, homozygous and heterozygous for the variant allele. The mean (SD) of blood lead (micrograms per deciliter), cortical bone (tibia) lead (micrograms per gram), and trabecular bone (patella) lead (micrograms per gram) were 6.2 (4.1), 22.1 (13.5), and 31.9 (19.5) in subjects who did not have the variant allele (ALAD 1-1), and 5.7 (4.2), 21.2 (10.9), and 30.4 (17.2) in the combined subjects who were either heterozygous or homozygous for the variant allele (ALAD 1-2 and ALAD 2-2). In multivariate linear regression models that controlled for age, education, smoking, alcohol ingestion, and vitamin D intake, the ALAD 1-1 genotype was associated with cortical bone lead levels that were 2.55 microg/g [95% confidence interval (CI) 0.05-5.05] higher than those of the variant allele carriers. We found no significant differences by genotype with respect to lead levels in trabecular bone or blood. In stratified analyses and a multivariate regression model that tested for interaction, the relationship of trabecular bone lead to blood lead appeared to be significantly modified by ALAD genotype, with variant allele carriers having higher blood lead levels, but only when trabecular bone lead levels exceeded 60 microg/g. These results suggest that the variant ALAD-2 allele modifies lead kinetics possibly by decreasing lead uptake into cortical bone and increasing the mobilization of lead from trabecular bone.

Aged↗
PubMed1999

Significant increase of a specific variant TSG101 transcript during the progression of cervical neoplasia.

The human tumour susceptibility gene TSG101 has recently been identified on chromosomal locus 11p15.1-15.2 which is frequently affected by genetic alterations in neoplastic lesions of the uterine cervix. Aberrant transcripts of the TSG101 gene have been reported in various tumour entities, including breast, ovarian and prostate cancers, but also in several non-neoplastic tissues. We analysed TSG101 transcription by reverse transcription-polymerase chain reaction (RT-PCR) in a total of 139 clinical samples of cervical tissues and in cervical carcinoma cell lines. Variant transcripts were observed in all cell lines, in 69 of 122 (57%) cervical dysplasia and carcinoma samples and in five of 17 (29%) normal cervical tissues. One specific variant TSG101 transcript (delta 154-1054) was detected with a significantly increased frequency in advanced preneoplastic cervical lesions. However, the relative abundance of variant TSG101 transcripts appeared to be generally low, as only wild-type, but no variant transcripts were detectable in Northern blot analyses of cervical carcinoma cell lines. These data point to a progressive loss of stringent splice control functions or to extended alternative splicing in advanced dysplasia and neoplasia. The relative amounts of variant transcripts do not support a major functional role of TSG101 variants in cervical carcinogenesis.

Blotting, Northern↗