Mutation and killing of Escherichia coli expressing a cloned Bacillus subtilis gene whose product alters DNA conformation.

Expression of the Bacillus subtilis gene coding for SspC, a small, acid-soluble protein, caused both killing and mutation in a number of Escherichia coli B and K-12 strains. SspC was previously shown to bind E. coli DNA in vivo, and in vitro this protein binds DNA and converts it into an A-like conformation. Analysis of revertants of nonsense mutations showed that SspC caused single-base changes, and a greater proportion of these were at A-T base pairs. Mutation in the recA gene abolished the induction of mutations upon synthesis of SspC, but the killing was only slightly greater than in RecA+ cells. Mutations in the umuC and umuD genes eliminated most of the mutagenic effect of SspC but not the killing, while the lexA mutation increased mutagenesis but did not appreciably affect the killing. Since there was neither killing nor mutation of E. coli after synthesis of a mutant SspC which does not bind DNA, it appears likely that the binding of wild-type SspC to DNA, with the attendant conformational change, was responsible for the killing and mutation. A strain containing the B. subtilis gene that is constitutive for the RecA protein at 42 degrees C showed a lower frequency of mutation when that temperature was used to induce the RecA protein than when the temperature was 30 degrees C, where the RecA level is low, suggesting that at the elevated temperature the high RecA level could be inhibiting binding of the B. subtilis protein to DNA

Stress-related genes and heroin addiction: A role for a functional FKBP5 haplotype

Background: Stress is a critical risk factor affecting both the development of and the relapse to drug addictions. Drug addictions are caused by genetic, environmental and drug-induced factors. The objective of this hypothesis-driven association study was to determine if genetic variants in stress-related genes are associated with heroin addiction

Synaptic Plasticity and Signal Transduction Gene Polymorphisms and Vulnerability to Drug Addictions in Populations of European or African Ancestry

AimDrug addiction is characterized, in part, by deregulation of synaptic plasticity in circuits involved in reward, stress, cue learning, and memory. This study was designed to assess whether 185 variants in 32 genes central to synaptic plasticity and signal transduction contribute to vulnerability to develop heroin and/or cocaine addiction.&nbsp; MethodsAnalyses were conducted in a sample of 1860 subjects divided according to ancestry (African and European) and drug of abuse (heroin or cocaine).&nbsp; ResultsEighteen SNPs in 11 genes (CDK5R1, EPHA4, EPHA6, FOSL2, MAPK3, MBP, MPDZ, NFKB1, NTRK2, NTSR1, and PRKCE) showed significant associations (P &lt; 0.01), but the signals did not survive correction for multiple testing. SNP rs230530 in the NFKB1 gene, encoding the transcription regulator NF-kappa-B, was the only SNP indicated in both ancestry groups and both addictions. This SNP was previously identified in association with alcohol addiction. SNP rs3915568 in NTSR1, which encodes neurotensin receptor, and SNP rs1389752 in MPDZ, which encodes the multiple PDZ domain protein, were previously associated with heroin addiction or alcohol addiction, respectively.&nbsp; ConclusionsThe study supports the involvement of genetic variation in signal transduction pathways in heroin and cocaine addiction and provides preliminary evidence suggesting several new risk or protective loci that may be relevant for diagnosis and treatment success.</p

Dopamine gene variants in opioid addiction: comparison of dependent patients, nondependent users and healthy controls

To determine whether specific dopaminergic system gene variants are associated with opioid dependence. Subjects included 153 healthy controls, 163 opioid exposed, but not dependent and 281 opioid dependent. Genotypes of 90 variants in 13 genes were examined. The most significant results were obtained for DA β-hydroxylase variants, rs2073837 and rs1611131, which were associated with protection from addiction (q = 0.0172, 0.0415, respectively) and the functional TH variant, rs2070762, was associated with more risk (q = 0.0387). The three variants also showed a combined effect that remained significant after correction for multiple testing (pfinal = 0.0039). These data offer support that dopaminergic gene variants have a role in opioid dependence and warrant further stud

Association of serotonin transporter (Sert) polymorphisms with opioid dependence and dimensional aspects of cocaine use in a caucasian cohort of opioid users

Introduction: A functional tandem repeat polymorphism in the promoter of the serotonin transporter (SERT) gene (SLC6A4) has been studied for association to neuropsychiatric conditions, including substance use disorders. Short (S) forms of this repeat result in reduced transcription, and presumably greater synaptic levels of serotonin, which are involved in opioid and cocaine-induced reward. Dual exposure to heroin and cocaine is a common pattern of poly-drug use and is associated with considerable morbidity. We hypothesize that SLC6A4 variants are associated with cocaine exposure in subjects with an opioid dependence diagnosis (OD), and also in non-dependent opioid users (NOD). Other single nucleotide polymorphisms (SNPs) of SLC6A4 may also be likewise associated. Materials and Methods: This study determined whether variants of the SLC6A4 promoter repeats and two intronic SNPs, rs16965628 and rs2066713, are associated with categorical diagnoses of opioid dependence (DSM-IV criteria) and with dimensional aspects of cocaine use, in a Caucasian cohort (n=591). Three groups of subjects were examined: (1) 276 subjects with opioid dependence diagnosis (OD); (2) 163 subjects who had used opioids for non-medical reasons but never had an opioid dependence diagnosis (NOD); (3) 152 healthy controls (HC). Results: Aside from high exposure to heroin in the OD group, relatively high exposure to cocaine was detected in both OD and NOD groups. The SERT repeat genotype (classified as “long-long” [LL] versus ”short-long” plus “short-short” [SL+SS]) was not associated with categorical opioid dependence diagnoses. A nominally significant association was identified with the [SL+SS] genotype of SLC6A4 and cocaine KMSK scores ≥“cutpoint” for a cocaine dependence diagnosis (p=0.026). The [SL+SS] genotype was associated with more rapid cocaine escalation than the LL genotype. No significant associations of rs16965628 and rs2066713 SNPs were found overall. Conclusion: The functional SERT promoter tandem repeat genotype may be associated to heavy cocaine exposure and more rapid escalation of cocaine use, in persons with and without opioid dependence diagnosis

Variants of opioid system genes are associated with non-dependent opioid use and heroin dependence

BACKGROUND: Heroin addiction is a chronic, relapsing brain disease. Genetic factors are involved in the development of drug addiction. The aim of this study was to determine whether specific variants in genes of the opioid system are associated with non-dependent opioid use and heroin dependence. METHODS: Genetic information from four subject groups was collected: non-dependent opioid users (NOD) [n=163]; opioid-dependent (OD) patients in methadone maintenance treatment (MMT) [n=143]; opioid-dependent MMT-resistant patients in heroin-assisted treatment (HAT) [n=138]; and healthy controls with no history of opioid use (HC) [n=153]. Eighty-two variants in eight opioid system genes were studied. To establish the role of these genes in (a) non-dependent opioid use, and (b) heroin dependence, the following groups were compared: HC vs. NOD; HC vs. OD (MMT+HAT); and NOD vs. OD (MMT+HAT). RESULTS: Five unique SNPs in four genes showed nominally significant associations with non-dependent opioid use and heroin dependence. The association of the delta opioid receptor (OPRD1) intronic SNP rs2236861 with non-dependent opioid use (HC vs. NOD) remained significant after correction for multiple testing (OR=0.032; pcorrected=0.015). This SNP exhibited a significant gene-gene interaction with prepronociceptin (PNOC) SNP rs2722897 (OR=5.24; pcorrected=0.041) (HC vs. NOD). CONCLUSIONS: This study identifies several new and some previously reported associations of variants with heroin dependence and with non-dependent opioid use, an important and difficult to obtain group not extensively studied previously. Further studies are warranted to confirm and elucidate the potential roles of these variants in the vulnerability to illicit drug use and drug addiction

Association of Variants of Arginine Vasopressin and Arginine Vasopressin Receptor 1A With Severe Acetaminophen Liver InjurySummary

Background & Aims: Acetaminophen-related acute liver injury and liver failure (ALF) result from ingestion of supratherapeutic quantities of this analgesic, frequently in association with other forms of substance abuse including alcohol, opioids, and cocaine. Thus, overdosing represents a unique high-risk behavior associated with other forms of drug use disorder. Methods: We examined a series of 21 single nucleotide polymorphisms (SNPs) in 9 genes related to impulsivity and/or stress responsivity that may modify response to stress. Study subjects were 229 white patients admitted to tertiary care liver centers for ALF that was determined to be due to acetaminophen toxicity after careful review of historical and biochemical data. Identification of relevant SNPs used Sanger sequencing, TaqMan, or custom microarray. Association tests were carried out to compare genotype frequencies between patients and healthy white controls. Results: The mean age was 37 years, and 75.6% were female, with similar numbers classified as intentional overdose or unintentional (without suicidal intent, occurring for a period of several days, usually due to pain). There was concomitant alcohol abuse in 30%, opioid use in 33.6%, and use of other drugs of abuse in 30.6%. The genotype frequencies of 2 SNPs were found to be significantly different between the cases and controls, specifically SNP rs2282018 in the arginine vasopressin gene (AVP, odds ratio 1.64) and SNP rs11174811 in the AVP receptor 1A gene (AVPR1A, odds ratio 1.89), both of which have been previously linked to a drug use disorder diagnosis. Conclusions: Patients who develop acetaminophen-related ALF have increased frequency of gene variants that may cause altered stress responsivity, which has been shown to be associated with other unrelated substance use disorders. Keywords: Impulsivity, Stress Responsivity, Pituitary-Adrenal Axis, Overdos