Search

Dystocia is a disorder characterized by prolonged or dysfunctional labour. Delivery that starts late or not at all, leads to an increased risk for Caesarean section, infant morbidity and mortality. Familial aggregations of dystocia suggest a polygenic background. We have studied three candidate genes for dystocia, i.e. the genes for testosterone 5-alpha reductase type 1, prostaglandin F2alpha receptor and endothelin 1 and performed mutational screening in 23 women with dystocia, of which 12 have affected relatives. No mutations were found, making it unlikely that any of these genes represent a major cause of dystocia in man. [ABSTRACT FROM AUTHOR]

Background: The TNFSF4/TNFRSF4 system, along with several other receptor-ligand pairs, is involved in the recruitment and activation of T-cells and is therefore tentatively implicated in atherosclerosis and acute coronary syndromes. We have previously shown that genetic variants in TNFSF4 are associated with myocardial infarction (MI) in women. This prompted functional studies of TNFSF4 expression., Methods and Results: Based on a screening of the TNFSF4 genomic region, a promoter polymorphism (rs45454293) and a haplotype were identified, conceivably involved in gene regulation. The rs45454293T-allele, in agreement with the linked rs3850641G-allele, proved to be associated with increased risk of MI in women. Haplotype-specific chromatin immunoprecipitation of activated polymerase II, as a measure of transcriptional activity in vivo, suggested that the haplotype including the rs45454293 and rs3850641 polymorphisms is functionally important, the rs45454293T- and rs3850641G-alleles being associated with lower transcriptional activity in cells heterozygous for both polymorphisms. The functional role of rs45454293 on transcriptional levels of TNFSF4 was clarified by luciferase reporter assays, where the rs45454293T-allele decreased gene expression when compared with the rs45454293C-allele, while the rs3850641 SNP did not have any effect on TNFSF4 promoter activity. Electromobility shift assay showed that the rs45454293 polymorphism, but not rs3850641, affects the binding of nuclear factors, thus suggesting that the lower transcriptional activity is attributed to binding of one or more transcriptional repressor(s) to the T-allele., Conclusions: Our data indicate that the TNFSF4 rs45454293T-allele is associated with lower TNFSF4 expression and increased risk of MI.

Coronary artery disease (CAD) is a leading cause of death world-wide, and most cases have a complex, multifactorial aetiology that includes a substantial heritable component. Identification of new genes involved in CAD may inform pathogenesis and provide new therapeutic targets. The PROCARDIS study recruited 2,658 affected sibling pairs (ASPs) with onset of CAD before age 66 y from four European countries to map susceptibility loci for CAD. ASPs were defined as having CAD phenotype if both had CAD, or myocardial infarction (MI) phenotype if both had a MI. In a first study, involving a genome-wide linkage screen, tentative loci were mapped to Chromosomes 3 and 11 with the CAD phenotype (1,464 ASPs), and to Chromosome 17 with the MI phenotype (739 ASPs). In a second study, these loci were examined with a dense panel of grid-tightening markers in an independent set of families (1,194 CAD and 344 MI ASPs). This replication study showed a significant result on Chromosome 17 (MI phenotype; p = 0.009 after adjustment for three independent replication tests). An exclusion analysis suggests that further genes of effect size lambda(sib) > 1.24 are unlikely to exist in these populations of European ancestry. To our knowledge, this is the first genome-wide linkage analysis to map, and replicate, a CAD locus. The region on Chromosome 17 provides a compelling target within which to identify novel genes underlying CAD. Understanding the genetic aetiology of CAD may lead to novel preventative and/or therapeutic strategies., Competing Interests: Competing interests. The authors have declared that no competing interests exist.

We recently showed that genetic variants in OX40L are associated with myocardial infarction (MI) and severity of coronary artery disease in human. A number of studies also suggest a possible role for OX40 (the OX40L receptor) as a factor contributing to atherosclerosis. In the present study, the OX40 gene was screened for variants associated with precocious MI, using individuals with MI before the age of 60 and controls. Despite the fact that the OX40 gene is highly conserved between species and that relatively few common genetic variants were encountered, an association with MI was seen for a polymorphism in intron 5 (rs2298212). In silico investigation suggested that genetic variation (rs2298211), linked to this intronic variant, is possibly affecting spliceosome function. Our results provide evidence that variants in human OX40 might influence susceptibility to MI. The relevance of these findings is supported by the vital functions fulfilled by OX40 in mammals as reflected by the high level of evolutionary conservation.

Ath1 is a quantitative trait locus on mouse chromosome 1 that renders C57BL/6 mice susceptible and C3H/He mice resistant to diet-induced atherosclerosis. The quantitative trait locus region encompasses 11 known genes, including Tnfsf4 (also called Ox40l or Cd134l), which encodes OX40 ligand. Here we report that mice with targeted mutations of Tnfsf4 had significantly (P

Platelet membrane glycoprotein IIb/IIIa plays an important role in platelet aggregation. A polymorphism of the gene encoding the IIIa subunit, with the two allele forms PLA1 and PLA2, has been identified. Some, but not all, studies suggest that the PLA2 allele confers an increased risk of suffering a myocardial infarction. Conversely, a recent study suggests that the PLA1 allele may contribute to early atherosclerosis and more rapid progression of stable coronary artery disease. To test whether these associations could be reproduced in a well-characterized sample of survivors of premature myocardial infarction, we examined 369 patients admitted to coronary care units in the Stockholm area who suffered a first myocardial infarction before the age of 60 years. There were no significant differences in extent of coronary artery disease according to PLA genotype group (based on quantitative coronary angiography). In addition, the frequencies of PLA1 and PLA2 alleles did not differ from those of 388 well-matched control subjects without coronary artery disease. These results suggest that the PLA1/PLA2 polymorphism of the platelet glycoprotein IIIa gene does not substantially contribute to the development of coronary atherosclerosis or the genetic susceptibility to premature myocardial infarction.

Endothelial growth factors have become the target of intense research since the initial discovery of vascular endothelial growth factor (VEGF/VPF). At present, VEGF is established as a major inducer of angiogenesis in normal and pathological conditions. Recently several new members in the VEGF family have been described; VEGF-B/VRF, VEGF-C and VEGF-D. VEGF-D is most closely related to VEGF-C by virtue of the presence of N- and C-terminal extensions that are not found in other VEGF family members. We have here examined the expression pattern of vegf-d mRNA with in situ hybridization in developing and adult mice. This shows a restricted expression pattern, with high levels mainly in lung tissue. The expression in embryonic lung is upregulated prior to birth. Expression of vegf-d in other tissues, as well as in lung tissue of the E14 embryo, was either low or absent. This suggests that VEGF-D may be of special relevance for the vascularization of lung tissue during the last trimester of fetal development., (Copyright 1999 Academic Press.)

This paper describes the genomic structure of the human Prostaglandin F receptor gene (FP) with its exon-intron borders and 5' flanking sequences. Furthermore, the location of the gene has been localized to a very small region on 1p31.1 using FISH and radiation hybrids analysis. The PGF receptor (FP) is highly expressed in mouse tissues especially in the corpora lutea in ovaries and in the kidney. Recently, it has been shown that homozygous knockout-mice lacking the gene for this receptor are unable to deliver normal fetuses at term. It might be speculated that the lack of the FP gene has the same effect in human as in mouse. Mutation analysis in families with difficulties in parturition would therefore be of high interest. The results presented here provides data necessary for further investigations of the FP gene., (Copyright 1999 Academic Press.)

The gene responsible for multiple endocrine neoplasia type 1 (MEN1), a heritable predisposition to endocrine tumours in man, has recently been identified. Here we have characterized the murine homologue with regard to cDNA sequence, genomic structure, expression pattern and chromosomal localisation. The murine Men1 gene spans approximately 6.7 kb of genomic DNA and is comprised of 10 exons with similar genomic structure to the human locus. It was mapped to the pericentromeric region of mouse chromosome 19, which is conserved with the human 11q13 band where MEN1 is located. The predicted protein is 611 amino acids in length and overall is 97% homologous to the human orthologue. The 45 reported MEN1 mutations which alter or delete a single amino acid in human all occur at conserved residues, thereby supporting their functional significance. Two transcripts of approximately 3.2 and 2.8 kb were detected in both embryonal and adult murine tissues, resulting from alternative splicing of intron 1. By RNA in situ hybridization and Northern analysis the spatiotemporal expression pattern of Men1 was determined during mouse development. Men1 gene activity was detected already at gestational day 7. At embryonic day 14 expression was generally high throughout the embryo, while at day 17 the thymus, skeletal muscle, and CNS showed the strongest signal. In selected tissues from postnatal mouse Men1 was detected in all tissues analysed and was expressed at high levels in cerebral cortex, hippocampus, testis, and thymus. In brain the menin protein was detected mainly in nerve cell nuclei, whereas in testis it appeared perinuclear in spermatogonia. These results show that Men1 expression is not confined to organs affected in MEN1, suggesting that Men1 has a significant function in many different cell types including the CNS and testis.

Apoptosis in murine myeloid cell lines requires the expression of the Requiem gene, which encodes a putative zinc finger protein. We detected the protein in both cytoplasmic and nuclear subcellular fractions of murine myeloid cells and human K562 leukemia cells, which suggests that the protein might have a function distinct from a transcription factor. This distribution did not alter upon apoptosis induction by IL-3 deprivation. As an approach to investigate its role in development, we determined the spatio-temporal expression pattern in the mouse. Expression was detected in various tissues in earlier gestational age; however, confined to testes, spleen, thymus, and part of the hippocampus in the adult mouse. The expression profile is consistent with a functional role during rapid growth and cell turnover, and in agreement with a regulatory function for hematopoietic cells. The human cDNA clone sequenced showed high homology to its murine counterpart and extended the open reading frame by 20 codons upstream. The gene is located in the proximal region of mouse Chromosome (Chr) 19. In the homologous human region at 11q13, it is located at about 150 kb centromeric from MLK3.

Human BCL6, also called LAZ3, is a protein involved in gene regulation and abnormal expression of BCL6 and has been implicated in the tumorigenesis of non-Hodgkin lymphoma. We have analyzed the expression of murin bcl6 in pre- and postnatal mouse using in situ hybridization histochemistry and Northern blotting. The developing olfactory epithelium in the nasal cavity was the only tissue displaying a positive bcl6 mRNA signal in the day 14 embryo. At gestational day 17, expression was primarily seen in skeletal muscle, olfactory epithelium, and thymus, and also in the epithelium lining the upper airways and esophagus. In selected tissues from postnatal mouse, bcl6 expression was detected in brain, renal cortex, spleen, and thymus. The expression in brain was restricted to the pyramidal cell layer of the cerebral cortex and the hippocampus regions CA1 and CA2, and the dentate gyrus. Our results show that bcl6 expression is not confined only to organs of the lymphatic system, such as spleen and thymus. Thus, bcl6 may be active as a regulator of gene transcription in many different cell types, including epithelial and nerve cells., (Copyright 1998 Academic Press.)

With the goal of better understanding the function and regulation of the different members of the VEGF family this study reports mapping of vegf, vegf-b and vegf-c mRNA expression in developing and adult mice. On embryonic day 14 (E14) there is a high expression of vegf and vegf-b, vegf-b being exceptionally high in heart and CNS. The vegf-c expression is lower with distinct signals in CNS and heart. Prior to birth (E17), vegf and vegf-b expression is moderately downregulated. Overlapping expression is present in intrascapular fat and heart. vegf dominates in thyroid and lung, while vegf-b appears to be the only VEGF member expressed at detectable levels in the CNS. In young adult mouse vegf and vegf-b show partly overlapping expression patterns particularly in kidney, heart and in the thymus, vegf displays higher levels in lung and liver, vegf-b appears to be dominating in brain, heart, testis and kidney. In brain the highest levels of vegf-b is present in the hippocampus. No vegf-c mRNA expression could be detected in the adult. Taken together, these results illustrate, in detail, the different regulations of the members of the VEGF gene family. There are at present at least three specific effectors of vascular proliferation with clear differences in their expression.

In this report we describe a sequence (PNG22) highly similar to the Phospholipase C beta3 Neighboring Gene (PNG). We also report that PNG22 is located in the q12 region on chromosome 22 between markers D22S1144 and D22S280. This finding explains that PNG probes cross hybridize to sequences on chromosome 22. Fine mapping using our sequence data and the complete sequence of a PAC clone (DJ515N1), located in this region, determined that PNG22 is located in intron 15 of the LIMK-2 gene. PNG22 is 93% homologous to PNG, however it do not have the introns described for the PNG gene, instead matching the cDNA sequence. This leads us to suggest that PNG22 probably represents a PNG pseudogene. In this report we also list the exon intron borders and the genomic structure of LIMK-2 and place it on the Sanger Center chromosome 22 Physical map. It also explains the finding that PNG probes cross hybridize to sequences on chromosome 22.

The estrogen receptor (ER) is a ligand-activated transcription factor that mediates the effects of the steroid hormone 17 beta-estradiol, in both males and females. Since the isolation and cloning of ER, the consensus has been that only one such receptor exists. The finding of a second subtype of ER (ER beta) has caused considerable excitement amongst endocrinologists. In this article, we present data regarding the genomic structure and chromosomal localization of the human ER beta gene, demonstrating that two independent ER genes do exist in the human. Furthermore, we present data regarding the tissue distribution of human ER beta, showing that this receptor is expressed in multiple tissues. For instance, ER beta is found in developing spermatids of the testis, a finding of potential relevance for the ongoing debate on the effects of environmental estrogens on sperm counts. In addition, we find ER beta in ovarian granulosa cells, indicating that estrogens also participate in the regulation of follicular growth in the human.

Multiple endocrine neoplasia type 1 (MEN1) is tightly linked to the muscle-type glycogen phosphorylase (PYGM) gene in 11q13. This region of the human genome contains additional disease-related loci implicated in the development of insulin-dependent diabetes mellitus, familial paraganglioma type 2, spinocerebellar ataxia type 5, Bardet-Biedl syndrome and translocation t(11;17) described in B-cell non-Hodgkin's lymphoma. We approached cloning of candidate disease genes from 11q13 by large-scale genomic sequencing. We obtained > 106 kb of sequence around the PYGM gene and established a transcriptional map that includes: (i) two genes previously localized to 11q13, PYGM and a zinc-finger protein (ZFM1) gene; (ii) the germinal center kinase (GCK, human B-lymphocyte serine/threonine protein kinase) gene; (iii) a novel human CDC25-like (HCDC25L) gene; (iv) a dystrophia myotonica protein kinase-like (DMPKL) gene; and (v) a novel ubiquitously expressed gene of unknown function (germinal center kinase- neighboring gene, GCKNG).

The predisposing genetic defect in multiple endocrine neoplasia type 1 has been assigned to chromosomal region 11q13. Our previous attempts to identify the MEN1 gene have resulted in the isolation of the phospholipase C beta 3 gene from the actual region. PLCB3 plays an important role in signal transduction and, moreover, shows loss of expression in some endocrine tumors, in accordance with a putative tumor suppressor gene function, and thus appears to be an excellent candidate for MEN1. We have therefore undertaken screening for constitutional mutations in individuals from MEN1 families. Several sequence alterations have been discovered, none of them however fulfilling the criteria for a disease-related mutation. We can now exclude PLCB3 from candidacy as the MEN1 gene.

Multiple endocrine neoplasia type 1 (MEN-1) is characterized by primary hyperparathyroidism, endocrine pancreatic-duodenal and anterior pituitary tumors. The diagnosis is challenging and involves the exclusion of other endocrine neoplasia syndromes with overlapping features. The predisposing genetic defect was assigned to chromosomal region 11q13 based on linkage analysis. Combined tumor and pedigree genotype analysis showed that allele losses in pancreatic, parathyroid and pituitary tumors eliminated the wild-type allele at the 11q13 loci, suggesting inactivation of a tumor suppressor gene in this region. A 5-Mb integrated map of the region has been established by the European consortium on MEN-1. Based on this mapping the critical interval was restricted to 2 Mb, a region within which eight candidate genes are located.

The universal chromophore of visual pigments in higher animals is 11-cis retinaldehyde. The final step in the biosynthetic pathway generating this compound is catalyzed by 11-cis retinol dehydrogenase, a membrane-bound enzyme abundantly expressed in the retinal pigment epithelium of the eye. In this work we demonstrate that the primary structure of human 11-cis retinol dehydrogenase is highly conserved with 91% identity to the bovine enzyme. The gene encoding 11-cis retinol dehydrogenase spans over approximately 4.1 kb of DNA and is divided into four translated exons. Analysis of a panel of somatic cells hybrids and fluorescence in situ hybridization on metaphase chromosomes revealed that the gene is located on chromosome 12q13-q14. Due to the unique role of 11-cis retinol dehydrogenase in the generation of visual pigments, it is a candidate gene for involvement in hereditary eye disease.

We describe the isolation and expression of a murine homologue of the Phospholipase C beta3 Neighboring Gene (PNG), located in the MEN1 region on chromosome 11q13. The PNG cDNA was isolated using a human PNG cDNA clone (SOM172). Human and mouse PNG do not have any marked similarity to other known genes on the DNA level, but the predicted protein display similarity to the C-terminal part of Phospholipase C beta2. Northern blots with mouse PNG probes revealed expression of a 1 kb message in multiple tissues, and an additional 2.3 kb band in testis. The predicted murine protein contains 203 amino acids. In situ hybridization histochemistry displayed png mRNA expression in several tissues of the midstage mouse embryo, including the central nervous system. In late stage embryos, png was highly expressed in skeletal muscle, retina and neocortex. In the adult animal, expression was restricted to testis and thymus.

Telomeres contains short tandem repeats (TTAGGG)n that are usually several kilobases in size. DNA sequences located next to the repeats are called telomere-associated or subtelomeric sequences. In this report we describe isolation and characterization of a new cDNA sequence isolated with a telomere specific, chromosome 17 genomic clone. No open reading frame of notable length could be detected. However comparison with sequences in the EMBL/Genbank revealed a 897 bp of close to perfect match, in the 3'end with the centromeric end of a genomic clone containing subtelomeric repeat sequences. The potential function of the SUBT1 transcript remains to be elucidated.

We describe here the molecular cloning and characterization of the murine homolog of the human vascular endothelial growth factor-related factor (VRF) gene. cDNAs for two alternatively spliced forms of the murine vrf gene have been isolated, the putative translation products of which differ at their carboxyl termini due to a shift in reading frame caused by insertion, or lack thereof, of exon 6, in a similar fashion to human VRF (hVRF). The message lacking exon 6 encodes a protein (mvrf167) with 86% identity and 92% conservation of amino acid residues with hVRF. The protein coding region of the gene spans approximately 5kb of genomic DNA and is composed of 8 exons ranging in size from 36 to 398bp. The genomic structure of murine vrf is highly conserved with the human homolog in relation to position of splice junctions and the presence of contiguous exons 6 and 7. A short polymorphic AC repeat is present in the 3' untranslated region of murine vrf. A major band of approximately 1.3kb was expressed in all adult mouse tissues examined.

Glutaredoxin is a small protein (12 kDa) catalyzing glutathione-dependent disulfide oxidoreduction reactions in a coupled system with NADPH, GSH, and glutathione reductase. A cDNA encoding the human glutaredoxin gene (HGMW-approved symbol GLRX) has recently been isolated and cloned from a human fetal spleen cDNA library. The screening of a human genomic library in Charon 4A led to the identification of three genomic clones. Using fluorescence in situ hybridization to metaphase chromosomes with one genomic clone as a probe, the human glutaredoxin gene was localized to chromosomal region 5q14. This localization at chromosome 5 was in agreement with the somatic cell hybrid analysis, using DNA from a human-hamster and a human-mouse hybrid panel and using a human glutaredoxin cDNA as a probe.

We have previously identified a novel gene closely related to the vasoactive endothelial growth factor (VEGF) gene. The human VEGF related factor (VRF) gene was initially isolated using an 11q13 specific cosmid probe (D11S750). Subsequently human VRF was used to isolate the corresponding mouse gene (vrf). Here, we report the spatiotemporal expression pattern of vrf during pre- and postnatal development. Mouse vrf gene expression starts early in fetal development. At day 14 post coitum it is expressed in most cells of the embryo although the heart, spinal cord and the cerebral cortex show significantly higher levels of expression than other tissues. At 17 days post coitum expression is almost exclusively seen in heart, brown fat and spinal cord. This pattern of expression could be consistent with a role of vrf as a growth factor in these tissues.

We describe the isolation, characterization, and genomic structure of a gene, Phospholipase C beta 3 Neighboring gene (PNG), located on chromosome 11q13. The cDNA was isolated using a cosmid that also contains the phospholipase C beta 3 gene (PLCB3). PNG does not have any marked similarity to other known genes on the DNA level. However, analysis of hybridization to a panel of somatic cell hybrids indicates the existence of related sequences on chromosomes 2, 4, 7, and 22. PNG showed expression of a 1-kb message in multiple tissues. The predicted protein is 199 amino acids. The gene spans approximately 2.5 kb, divided into four exons and three introns. It is located 4.4 kb upstream of PLCB3, with the 5' ends facing each other. The intergenic region has been completely sequenced, revealing separate CpG islands at both ends of this region. The islands are separated by a stretch of 2 kb, characterized by periodic alteration of the GC content. The 5'-flanking region of PNG does not contain TATA or CCAAT, suggesting a housekeeping promoter structure.

Protein phosphorylation plays a crucial role in the regulation of a wide array of proteins involved in many cellular processes. Protein phosphatase 5 (PP5) is a novel member of the protein serine/threonine phosphatase family. The majority of the cDNA sequence of PP5 has been reported recently. In our study, a sequence encoding the whole open reading frame of PP5 was cloned from a human fetal brain cDNA library. The protein phosphatase cDNA sequence of our clone is longer at the 5' end than the recently published sequence. It's likely that the extended sequence contains the start codon ATG, since a translation stop codon TAG is present upstream of the ATG codon in the same open reading frame. The mRNA of the PP5 gene was detected in all the human tissues examined. The PP5 gene was localized to human chromosomal region 19q13.3.

Phospholipase Cbeta3 (PLCbeta3) is a member of the family of phospholipase C isoenzymes, a second messenger system that plays an important role in initiating receptor-mediated signal transduction in response to extracellular signals. Using RNA in situ hybridization we showed that in the embryonic rat nervous system, PLCbeta3 is expressed in dorsal root ganglia (DRGs) and the trigeminal ganglion. Characterization of the hybridization signal in the adult rat nervous system revealed that PLCbeta3 expression is confined mainly to small-sized DRG neurons. In non-neuronal tissues, PLCbeta3 is expressed by cells of epithelial origin, such as skin and the mucous lining airways and the gastrointestinal canal, and in lung and thymus.

We have characterized the complete cDNA sequence, genomic structure, and expression of the human phosphoinositide-specific phospholipase C beta 3 (PLC beta 3) gene (gene symbol PLCB3). PLC beta 3 plays an important role in initiating receptor-mediated signal transduction. Activation of PLC takes place in many cells as a response to stimulation by hormones, growth factors, neurotransmitters, and other ligands. The partial cDNA sequence of PLC beta 3, previously published, was extended with 876 bp in the 5' direction, giving a transcript of 4400 bp and a total open reading frame of 1234 amino acids. This was in accordance with expression analysis by Northern blotting that revealed a single 4.4-kb transcript in all tissues tested. Genomic data were obtained by sequencing plasmid subclones of a cosmid that contained the whole gene. The size of the complete transcription unit was estimated to be on the order of 15 kb. The gene contains 31 exons, with all splice donor and acceptor sites conforming to the GT/AG rule. No exon exceeds 571 bp in length, and the shortest exon spans only 36 bp. More than half of the introns are smaller than 200 bp, with the smallest being only 79 bp long. The transcription initiation site was determined to be within an 8-bp cluster 328-321 bp upstream of the translation initiation site. The 5'flanking region is highly GC rich, with multiple CpG doublets, and contains multiple binding sites for Sp1. Lacking typical transcriptional regulatory sequences such as TATA and CAAT boxes, the putative promoter region conforms to the group of housekeeping promoters.

The regulation of CYP2E1 and 2B1 was studied by following mRNA levels, catalytic activities and the subcellular distribution of the apoproteins in rat liver 0, 6, 12, 24, 48 and 96 h after a single intragastric dose of acetone. No changes were observed in hepatic CYP2E1 mRNA levels at any time after acetone treatment, whereas rapid rises were observed in the microsomal amount of CYP2E1 protein and CYP2E1-catalyzed 4-nitrophenol hydroxylase and carbon-tetrachloride-initiated lipid-peroxidation activities. However, CYP2E1-dependent catalytic activities declined much faster than the immunodetectable CYP2E1 protein, suggesting that this cytochrome P-450 is inactivated prior to degradation. Similar results were seen in primary hepatocyte cultures. By contrast, concomitant changes in levels of CYP2B1 and CYP2B1-dependent O-depentylation of pentoxyresorufin were observed in the same microsomal preparations. Investigation of the degradative mechanism of both CYP2E1 and CYP2B1 by immunoquantitation of the proteins in lysosomes and by immunohistochemistry indicated their degradation via an autophagic-lysosomal pathway. The data suggest that CYP2E1 is acutely inactivated in the endoplasmic reticulum and that degradation of this isozyme occurs, at least in part, by the lysosomal route. By contrast, CYP2B1 is principally controlled at the level of synthesis.