The influence of FKBP5 genotype on expression of FKBP5 and other glucocorticoid-regulated genes, dependent on trauma exposure

The FK506 binding protein 51 (FKBP5), an intrinsic regulator of the glucocorticoid receptor, has been associated with pathological behaviors particularly in the context of childhood trauma (CT), via a putatively regulatory polymorphism, rs1360780. However, trans- and cis-acting effects of this locus and its interaction with CT are incompletely understood. To study its effects on the expression of glucocorticoid-regulated genes including FKBP5, we used lymphoblastoid cell lines (LCLs) derived from 16 CT-exposed patients with greater than two substance dependence/suicidal behavior diagnoses (casesCT+) and 13 non-CT-exposed controls (controlsCT-). This study in LCLs measures long-term trait-like differences attributable to genotype or lasting epigenetic modification. Through analysis of differential allelic expression (DAE) using an FKBP5 3'-UTR reporter single nucleotide polymorphism (SNP), rs3800373, that is in strong linkage disequilibrium with rs1360780, we confirmed that the rs1360780 risk allele (A) (or conceivably that of a linked SNP) leads to higher FKBP5 expression in controlsCT-. Intriguingly, casesCT+ did not show DAE, perhaps because of a genotype-predicted difference in FKBP5 DNA methylation restricted to casesCT+. Furthermore, through correlation analyses on FKBP5 expression at baseline and after induction by dexamethasone, we observed that casesCT+ had lower induction of FKBP5 expression, indicating that overall they may have strong ultra-short negative-feedback. Only casesCT+ showed an effect of rs1360780 genotype on expression of FKBP5 and other glucocorticoid-regulated genes. Together, these results confirm that the rs1360780 locus alters FKBP5 expression and further that in trans-fashion this locus affects the expression of other glucocorticoid-regulated genes after a glucocorticoid challenge. The CT exposure appears to be essential for trans-effects of rs1360780 on glucocorticoid-regulated genes.

DRD2 dopamine receptor genotype, linkage disequilibrium, and alcoholism in American Indians and other populations

We defined interpopulation differences in the frequency of the dopamine D2 receptor DRD2/Taq1 A1 allele, which has previously been associated with alcoholism. Frequencies of the A1 allele in unrelated subjects were 0.18 to 0.20 (se = 0.02 to 0.03) in several Caucasian populations previously assessed, 0.38 (+/- 0.05) in American Blacks (n = 44), 0.63 (+/- 0.07) in Jemez Pueblo Indians (n = 23), and 0.80 (+/- 0.04) in Cheyenne Indians (n = 52). The existence of large interpopulation differences in the frequency of the Taq1 alleles suggests that associations to disease status could readily be generated or masked if disease and control groups were uneven in ethnic composition. To address the possibility that the 4-fold higher frequency of the A1 allele in Cheyenne Indians was related to an increased vulnerability to alcoholism in that population, 47 Cheyenne Indians were psychiatrically interviewed and blind-rated. However, there was no significant difference between interviewed controls (0.73 +/- 0.06, n = 24), subjects with alcoholism and/or drug abuse (0.74 +/- 0.06, n = 23) and noninterviewed population controls (0.87 +/- 0.05, n = 20). Legitimate association of the DRD2/Taq1 allele to alcoholism would presumably require it to be in linkage disequilibrium (nonrandom association) with a functional mutation at DRD2 or elsewhere. The level of disequilibrium would vary between populations and could place an upper bound on the strength of an association.(ABSTRACT TRUNCATED AT 250 WORDS)

Human brain tumor--derived cell lines: growth rate reduced by human fibroblast interferon

The biological response modifier human beta-interferon had pronounced antigrowth effects on various histologic types of human brain tumor cells but no effects on a nontransformed cell line, MRC-5. The cultures of brain tumor cells showed severe alterations indicative of cell injury and death after exposure to beta-interferon for 2 to 6 days. Similar results were obtained with cells freshly explanted from human brain tumors. The results indicate that it may be possible to use fresh, explanted tumor tissue to identify patients who might benefit from therapy with beta-interferon.