Sensory nerve recording for closed-loop control to restore motor functions

A method is developed for using neural recordings to control functional electrical stimulation (FES) to nerves and muscles. Experiments were done in chronic cats with a goal of designing a rule-based controller to generate rhythmic movements of the ankle joint during treadmill locomotion. Neural signals from the tibial and superficial peroneal nerves were recorded with cuff electrodes and processed simultaneously with muscular signals from ankle flexors and extensors in the cat's hind limb. Cuff electrodes are an effective method for long-term chronic recording in peripheral nerves without causing discomfort or damage to the nerve. For real-time operation we designed a low-noise amplifier with a blanking circuit to minimize stimulation artifacts. We used threshold detection to design a simple rule-based control and compared its output to the pattern determined using adaptive neural networks. Both the threshold detection and adaptive networks are robust enough to accommodate the variability in neural recordings. The adaptive logic network used for this study is effective in mapping transfer functions and therefore applicable for determination of gait invariants to be used for closed-loop control in an FES system. Simple rule-bases will probably be chosen for initial applications to human patients. However, more complex FES applications require more complex rule-bases and better mapping of continuous neural recordings and muscular activity. Adaptive neural networks have promise for these more complex applications.

Application of tilt sensors in functional electrical stimulation

Tilt sensors, or inclinometers have been investigated for the control of Functional Electrical Stimulation (FES) to improve the gait of persons who had a stroke or incomplete spinal cord injury (SCI). Different types of tilt sensors were studied for their characteristics and their performance in measuring the angular displacement of leg segments during gait. Signal patterns of the lower leg with inertial tilt sensors were identified with control subjects and subjects with footdrop who are being stimulated during level walking. To minimize acceleration responses when the foot swings or hits the ground, we use low-pass filtering (1.5-2 Hz). A finite state approach allows the sensor fixed on the shank to effectively detect the step intention in a population of stroke and incomplete SCI subjects and to control the FES. When the lower leg tilts backward, the common peroneal nerve is stimulated to bring the foot up and forward. We have designed a miniature footdrop stimulator with a magnetoresistive tilt sensor built in, so no external sensor cables are required. The thresholds to turn the stimulator on and off can be adjusted, as well as the maximum period of stimulation and the minimum interval between periods of stimulation. This device features several important advantages over traditional AFO's or stimulators controlled by foot switches. Initial trials with stroke and SCI subjects have demonstrated substantial gait improvement for some subjects, while most liked the good cosmesis and ease of using the device with a tilt sensor.

Interaction of the human immunodeficiency virus type 1 nucleocapsid with actin

The nucleocapsid (NC) domain of the retrovirus Gag protein plays several important roles in the viral life cycle, including virus assembly, viral genomic RNA encapsidation, primer tRNA placement, and enhancement of viral reverse transcription. In this study, deletion of NC domain of human immunodeficiency virus type 1 (HIV-1) Gag was found to drastically reduce virus particle production in CD4(+) T cells. Cellular fractionation experiments showed that although most of the uncleaved wild-type HIV-1 Gag, unmyristylated Gag, and p6(Gag) domain-truncated Gag molecules copurified with the host cell cytoskeleton, most of the mutant Gag molecules lacking both the NC and p6(Gag) domains failed to cofractionate with cytoskeleton. In wild-type virus-infected cells, in which the viral protease was active, the cleaved NCp7 copurified with the cytoskeleton, whereas most of the MAp17 and CAp24 did not. Monoclonal antibody against actin coimmunoprecipitated full-length Gag and p6(Gag) domain-truncated Gag molecules from cell lysates but failed to precipitate the truncated mutant Gag molecules lacking NC plus p6(Gag). Purified recombinant NCp7, but not CAp24, was able to bind F-actin in cosedimentation experiments. Furthermore, wild-type NCp7 and a zinc finger mutant NCp7(F16A), like a cellular actin-binding protein (the villin headpiece), bound F-actin in a dose-dependent fashion in vitro. Taken together, these results suggest that HIV-1 NCp7 can bind F-actin directly and that interaction between HIV-1 Gag and the actin cytoskeleton through the NC domain may play an important role in HIV-1 assembly and/or other steps of the viral life cycle.

c-Jun NH2-terminal kinase targeting and phosphorylation of heat shock factor-1 suppress its transcriptional activity

The mammalian heat shock transcription factor HSF-1 regulates the expression of the heat shock proteins, molecular chaperones that are involved in cellular processes from higher order assembly to protein degradation. HSF-1 is a phosphorylated monomer under physiological growth conditions and is located mainly in the cytoplasm. Upon activation by a variety of environmental stresses, HSF-1 is translocated into the nucleus, forms trimers, acquires DNA binding activity, is hyperphosphorylated, appears as punctate granules, and increases transcriptional activity of target genes. As cells recover from stress, the punctate granules gradually disappear, and HSF-1 appears in a diffused staining pattern in the cytoplasm and nucleus. We have previously shown that the mitogen-activated protein kinase ERK phosphorylates and suppresses HSF-1-driven transcription. Here, we show that c-Jun NH(2)-terminal kinase (JNK) also phosphorylates and inactivates HSF-1. Overexpression of JNK facilitates the rapid disappearance of HSF-1 punctate granules after heat shock. Similar to ERK, JNK binds to HSF-1 in the conserved mitogen-activated protein kinases binding motifs and phosphorylates HSF-1 in the regulatory domain. The overexpression of an HSF-1-green fluorescent protein fusion construct lacking JNK phosphorylation sites causes this HSF-1 mutant to form nuclear granules that remain longer in the nucleus after heat shock. Taken together, these findings indicate that JNK phosphorylates HSF-1 and suppresses its transcriptional activity by rapidly clearing HSF-1 from the sites of transcription.

Assessment of specificity of eight chemical inhibitors using cDNA-expressed cytochromes P450

1. The selectivity of eight chemical inhibitors has been extensively evaluated with 10 cDNA-expressed human cytochrome P450 isoforms (CYP). The results indicate that sulphaphenazole, quinidine and alpha-naphthoflavone are selective inhibitors of CYP2C9 (IC50 = 0.5-0.7 microM), CYP2D6 (0.3-0.4 microM) and CYP1A (0.05-5 microM) respectively on the basis of the IC50, which are much lower than those of other P450 isoforms (> 10-fold). 2. Ketoconazole exhibited potent inhibition of both CYP3A4-catalysed metabolism of phenanthrene, testosterone, diazepam (IC50 = 0.03-0.5 microM) and CYP1A1-catalysed deethylation of 7-ethoxycoumarin (0.33 microM). The selectivity of ketoconazole for other P450s was highly related to the concentration used. 3. Diethyldithiocarbamate, orphenadrine and furafylline were shown separately to be less selective inhibitors of CYP2E1, CYP2B6 and CYP1A isoforms by a broad range of IC50 that overlap those observed with other P450 isoforms. 4. Furafylline, quinidine and alpha-naphthoflavone activated CYP3A4-catalysed phenanthrene metabolism by 1.7-, 2- and 15-fold respectively. 5. The selectivity of orphenadrine and ketoconazole was further examined by using inhibitory monoclonal antibodies (MAb). Inhibitory MAb specific for the individual P450 isoforms may be of greater value than chemical inhibitors.

The human peroxisome proliferator-activated receptor alpha gene: identification and functional characterization of two natural allelic variants

Peroxisome proliferator-activated receptor (PPAR)alpha-null mice have a defect in fatty acid metabolism but reproduce normally. The lack of a detrimental effect of the null phenotype in development and reproduction opens up the possibility for null or variant PPARalpha gene (PPARA) alleles in humans. To search the coding region and splice junctions for mutant and variant PPARalpha alleles, the human PPARalpha gene was cloned and characterized, and sequencing by polymerase chain reaction was carried out. Two point mutations in the human gene were found in the DNA binding domain at codons for amino acids 131 and 162. The allele containing the mutation in codon 162 (CTT to GTT, L162V) designated PPARA*3, was found at a high frequency in a Northern Indian population. Transfection assays of this mutant showed that the non-ligand dependent transactivation activity was less than one-half as active as the wild-type receptor. PPARA*3 was also unresponsive to low concentrations of ligand as compared to the wild-type PPARA*1 receptor. However, the difference is ligand concentration-dependent; at concentrations of the peroxisome proliferator Wy-14 643 > 25 microM, induction activity was restored in this variant's transactivation activity to a level five-fold greater as compared with wild-type PPARA*1 with no ligand. The mutation in codon 131 (CGA to CAA, R131Q), designated PPARA*2 is less frequent than PPARA*3, and the constitutive ligand independent activity was slightly higher than PPARA*1. Increasing concentrations of Wy-14 643 activated PPARA*2 similar to that observed with PPARA*1. The biological significance of these novel PPARalpha alleles remains to be established. It will be of great interest to determine whether these alleles are associated with differential response to fibrate therapy.

A kinetic model for the metabolic interaction of two substrates at the active site of cytochrome P450 3A4

In many cases, CYP3A4 exhibits unusual kinetic characteristics that result from the metabolism of multiple substrates that coexist at the active site. In the present study, we observed that alpha-naphthoflavone (alpha-NF) exhibited a differential effect on CYP3A4-mediated product formation as shown by an increase and decrease, respectively, of the carboxylic acid (P(2)) and omega-3-hydroxylated (P(1)) metabolites of losartan, while losartan was found to be an inhibitor of the formation of the 5,6-epoxide of alpha-NF. Thus, to address this problem, a kinetic model was developed on the assumption that CYP3A4 can accommodate two distinct and independent binding domains for the substrates within the active site, and the resulting velocity equations were employed to predict the kinetic parameters for all possible enzyme-substrate species. Our results indicate that the predicted values had a good fit with the experimental observations. Therefore, the kinetic constants can be used to adequately describe the nature of the metabolic interaction between the two substrates. Applications of the model provide some new insights into the mechanism of drug-drug interactions at the level of CYP3A4.

Identification of protein carbonyls after two-dimensional electrophoresis

The oxidative modification of proteins plays a major role in a number of human diseases, but identity of the specific proteins that are most susceptible to oxidation has posed a difficult problem. Protein carbonyls are increased after oxidative stress, and after derivatization with 2,4-dinitrophenyl hydrazine (DNP) they can be detected by various analytical and immunological methods. Although high resolution two-dimensional electrophoresis (2-DE) can resolve virtually all proteins present in a cell or tissue it has been difficult to determine the oxidized proteins because the DNP-derivatization process alters the isoelectric points of proteins, and additional procedures must be utilized to remove reaction byproducts. These additional procedures can lead to loss of sample, and poor isoelectric resolution on immobilized pH gradient (IPG) strips. We have developed a method that allows the IPG strips to be derivatized with DNP directly following isoelectric focusing of the proteins. This method allows the visualization of oxidized proteins by 2-DE with high reproducibility.

Relationship between psychosocial factors and onset of multiple sclerosis

OBJECTIVE

The aim of this study was to investigate the influence of psychosocial variables on patients with multiple sclerosis (MS) and the relationship between these variables and the onset of MS.

BACKGROUND

The current evidence indicates that many types of psychosocial factors are involved in the development and relapse of MS, and it has been suggested that they could serve as predictors as well. So far, little has been reported on the effect of psychosocial factors on MS and the relationship between psychosocial factors and the onset of MS.

METHODS

Forty-one patients, 15 males and 26 females, average age 37.44 +/- 12.24 years (mean +/- SD), were evaluated by the Life Event Scale, Eysenck Personality Questionnaire, Social Support Revaluate Scale and Symptom Check List 90 and compared with 41 equivalent healthy control subjects, 15 males and 26 females, average age 36.38 +/- 12.84 years (mean +/- SD). Disease, demographic, psychosocial and lifestyle factors were measured at baseline. Patients with MS were first diagnosed by 3 neurologists according to the Poser (1983) MS diagnostic criteria.

RESULTS

Significant differences were found between the MS and the control group in their negative emotions and symptoms such as depression, anxiety, obsession, phobia, tense interpersonal relationship and somatization disorder. Significant differences were found between the two groups in the total number of negative life events, their family problems and the utilization of social support. The scores for various negative emotions in the MS group correlated positively with those for neuroticisms in personality type, and negatively with those for introverted and extroverted personality. Many kinds of negative emotions in the MS group correlated positively with the total number of life events, negative life events and family problems. Many kinds of negative emotions in the MS group correlated negatively with the utilization of social support.

CONCLUSION

The psychosocial factors are closely associated with MS onset and may play important roles in the development of the disease.

High and low doses of haptens dictate whether dermal or epidermal antigen-presenting cells promote contact hypersensitivity

In the induction of contact hypersensitivity (CH) to an epicutaneously applied hapten, we have previously proposed that low doses of hapten sensitize primarily through epidermal Langerhans' cells (LC), whereas high doses rely largely on dermal antigen-presenting cells (APC). To examine this issue further, we applied either high or low doses of dinitrofluorobenzene (DNFB) epicutaneously to mice. We observed reduced LC density at the site after 12 h (nadir), which returned to normal levels at 24 h only after a low dose of hapten. When a low dose of an unrelated hapten, oxazolone, was painted on skin that had been painted 12 h previously with high dose of DNFB, oxazolone-specific CH was impaired. When grafts of whole skin, dermis alone, and epidermis alone prepared from skin painted 2 h previously with low or high doses of DNFB were placed onto naive, syngeneic mice, CH was induced by whole skin after both types of doses, by epidermis only after a low dose, and by dermis only after high dose. When epidermal cell suspensions were derivatized in vitro with low or high doses of DNFB, only cells exposed to a low dose induced proliferation of hapten-specific Tcells. Thus, only a low dose of hapten reveals the APC functions of LC without the participation of dermal APC.

Gankyrin drives malignant transformation of chronic liver damage-mediated fibrosis via the Rac1/JNK pathway

Hepatocarcinogenesis is a complex process involving chronic liver injury, inflammation, unregulated wound healing, subsequent fibrosis and carcinogenesis. To decipher the molecular mechanism underlying transition from chronic liver injury to dysplasia, we investigated the oncogenic role of gankyrin (PSMD10 or p28^GANK) during malignant transformation in a transgenic mouse model. Here, we find that gankyrin increased in patients with cirrhosis. In addition to more severe liver fibrosis and tumorigenesis after DEN plus CCl₄ treatment, hepatocyte-specific gankyrin-overexpressing mice (gankyrin^hep) exhibited malignant transformation from liver fibrosis to tumors even under single CCl₄ administration, whereas wild-type mice merely experienced fibrosis. Consistently, enhanced hepatic injury, severe inflammation and strengthened compensatory proliferation occurred in gankyrin^hep mice during CCl₄ performance. This correlated with augmented expressions of cell cycle-related genes and abnormal activation of Rac1/c-jun N-terminal kinase (JNK). Pharmacological inhibition of the Rac1/JNK pathway attenuated hepatic fibrosis and prevented CCl₄-induced carcinogenesis in gankyrin^hep mice. Together, these findings suggest that gankyrin promotes liver fibrosis/cirrhosis progression into hepatocarcinoma relying on a persistent liver injury and inflammatory microenvironment. Blockade of Rac1/JNK activation impeded gankyrin-mediated hepatocytic malignant transformation, indicating the combined inhibition of gankyrin and Rac1/JNK as a potential prevention mechanism for cirrhosis transition.

Heat shock factor-4 (HSF-4a) is a repressor of HSF-1 mediated transcription

Heat shock transcription factors (HSFs) regulate the expression of heat shock proteins and other molecular chaperones that are involved in cellular processes from higher order assembly to protein degradation and apoptosis. Among the human HSFs, HSF-4 is expressed as at least two splice variants. One isoform (HSF-4b) possesses a transcriptional activation domain, but this region is absent in the other isoform (HSF-4a). We have recently shown that the HSF-4a isoform represses basal transcription from heterologous promoters both in vitro and in vivo. Here we show that HSF-4a and HSF-4b have dramatically different effects on HSF-1-containing nuclear bodies, which form after heat shock. While the expression of HSF-4b colocalizes with nuclear granules, the expression of HSF-4a prevents their formation. In addition, there is a concurrent reduction of HSF-1 in the nucleus, and there is reduction in its DNA binding activity and in HSE-dependent transcription of a reporter gene. To better understand the mechanism by which HSF-4a represses transcription, we inducibly expressed HSF-4a in cells and found that HSF-4a binds to the heat shock element (HSE) during attenuation of the heat shock response. Thus HSF-4a is an active repressor of HSF-1-mediated transcription. This repressor function makes the HSF-4a isoform unique within the HSF family.

Comparison of effectiveness and safety between conbercept and ranibizumab for treatment of neovascular age-related macular degeneration. A retrospective case-controlled non-inferiority multiple center study

Purpose

To compare the efficacy and safety of conbercept and ranibizumab when administered according to a treat-and-extend (TREX) protocol for the treatment of neovascular age-related macular degeneration (AMD) in China.

Patients and methods

Between May 2014 and May 2015, 180 patients were treated in a 1 : 1 ratio using conbercept or ranibizumab from four hospitals. Patients received either conbercept 0.5 mg or ranibizumab 0.5 mg intravitreal injections. Follow-up time was 1 year and treated based on a TREX approach. Main outcomes and measures include best-corrected visual acuity (BCVA), using Early Treatment Diabetic Retinopathy Study (ETDRS); number of injections; central retinal thickness (CRT); and leakage of choroidal neovascularization before and after the treatment was analyzed by fluorescein fundus angiography and indocyanine green angiography.

Results

The 1-year visit was completed by 168 (93.3%) of patients. Mean BCVA was equivalent between two cohorts, and were improved by 12.7±7.770 and 12.3±7.269 letters in the conbercept and ranibizumab cohorts, respectively (P=0.624). There was no significant difference in measured CRT, with a mean decrease of 191.5 μm for conbercept and 187.8 μm for ranibizumab (P=0.773). There was a statistically significant difference (P=0.001) between the drugs regarding the number of treatments: 7.4 for conbercept and 8.7 for ranibizumab. The difference in the distribution of injection intervals was statistically significant between two groups (P=0.011). During the study, there were no cases of endophthalmitis or intraocular inflammation.

Conclusion

Both drugs had equivalent effects in visual and anatomic gains at 1 year when administered. In the conbercept group, longer treatment intervals were achieved with more patients.

Heat shock factor-4 (HSF-4a) represses basal transcription through interaction with TFIIF

The heat shock transcription factors (HSFs) regulate the expression of heat shock proteins (hsps), which are critical for normal cellular proliferation and differentiation. One of the HSFs, HSF-4, contains two alternative splice variants, one of which possesses transcriptional repressor properties in vivo. This repressor isoform inhibits basal transcription of hsps 27 and 90 in tissue culture cells. The molecular mechanisms of HSF-4a isoform-mediated transcriptional repression is unknown. Here, we present evidence that HSF-4a inhibits basal transcription in vivo when it is artificially targeted to basal promoters via the DNA-binding domain of the yeast transcription factor, GAL4. By using a highly purified, reconstituted in vitro transcription system, we show that HSF-4a represses basal transcription at an early step during preinitiation complex assembly, as pre-assembled preinitiation complexes are refractory to the inhibitory effect on transcription. This repression occurs by the HSF-4a isoform, but not by the HSF-4b isoform, which we show is capable of activating transcription from a heat shock element-driven promoter in vitro. The repression of basal transcription by HSF-4a occurs through interaction with the basal transcription factor TFIIF. TFIIF interacts with a segment of HSF-4a that is required for the trimerization of HSF-4a, and deletion of this segment no longer inhibits basal transcription. These studies suggest that HSF-4a inhibits basal transcription both in vivo and in vitro. Furthermore, this is the first report identifying an interaction between a transcriptional repressor with the basal transcription factor TFIIF.

Disease-associated fibronectin matrix fragments trigger anoikis of human primary ligament cells: p53 and c-myc are suppressed

Inflammation in periodontal disease is characterized by the breakdown of the extracellular matrix. This study shows that an inflammation-associated matrix breakdown fragment of fibronectin (FN) induces anoikis of human periodontal ligament (PDL) cells. This 40 kDa fragment was identified in human inflammatory crevicular fluid and is associated with disease status. Previously, we reported that a similar recombinant FN fragment triggered apoptosis of PDL cells by an alternate apoptotic signaling pathway that requires transcriptional downregulation of p53 and c-myc. Thus, to determine whether the physiologically relevant 40 kDa fragment triggers apoptosis in these cells, the 40 kDa fragment was generated and studied for its apoptotic properties. The 40 kDa fragment induces apoptosis of PDL cells, and preincubation of cells with intact vitronectin, FN, and to a limited extent collagen I, rescue this apoptotic phenotype. These data suggest that the 40 kDa fragment prevents PDL cell spreading, thereby inducing anoikis. The signaling pathway also involves a downregulation in p53 and c-myc, as determined by Western blotting and real time quantitative PCR. These data indicate that an altered FN matrix as is elaborated in inflammation induces anoikis of resident cells and thus may contribute to disease progression.

Molecular modeling of mammalian cytochrome P450s

The cytochrome P450s are a superfamily of hemoprotein enzymes responsible for the metabolism of a wide variety of xenobiotic and endogenous compounds. The individual P450s exhibit unique substrate specificity and stereoselectivity profiles which reflect corresponding differences in primary sequence and tertiary structure. In the absence of an experimental structure models for mammalian P450s have been generated by their homology with bacterial P450s of known structure. The rather low sequence identity between target and template proteins renders P450 modeling a challenging task. However, the substrate recognition properties of several P450s are consistent with recently developed working models. This review summarizes the major concepts and current approaches of molecular modeling of P450s.

Inhibition of human cytochrome P450 1A2 by flavones: a molecular modeling study

Cytochrome P450 1A2 metabolizes a number of important drugs, procarcinogens, and endogenous compounds. Several flavones, a class of phytochemicals consumed in the human diet, have been shown to differentially inhibit human P450 1A2-mediated methoxyresorufin demethylase. A molecular model of this P450 was constructed in order to elucidate the molecular basis of the P450-flavone interaction. Flavone and its 3,5,7-trihydroxy and 3,5,7-trimethoxy derivatives were docked into the active site to assess their mode of binding. The site is hydrophobic and includes several residues that hydrogen bond with substituents on the flavone nucleus. The binding interactions of these flavones in the modeled active side are consistent with their relative inhibitory potentials, namely 3,5,7-trihydroxylflavone > flavone > 3,5,7-trimethoxylflavone, toward P450 1A2-mediated methoxyresorufin demethylation.

Ultraviolet B-exposed and soluble factor-pre-incubated epidermal Langerhans cells fail to induce contact hypersensitivity and promote DNP-specific tolerance

Acute low-dose ultraviolet B (UVB) radiation impairs the induction of contact hypersensitivity (CH) and induces tolerance in UVB-susceptible strains of mice when dinitrofluorobenzene (DNFB) is applied to an irradiated skin surface. We are interested in learning the cellular and molecular bases for the existence of UVB susceptibility in certain strains of mice. CH was induced by subcutaneous injections into naive syngeneic C57BL/6 and BALB/c mice of dinitrophenyl (DNP)-derivatized Thy-1(+)-depleted epidermal cells enriched for Ia+ cells (LC/DNP, 2 x 10(4) cells per mouse). Tolerance was detected by applying 185 microg of DNFB epicutaneously to mice treated 2 wk earlier with a putative tolerating regimen and testing CH expression. We found that LC/DNP obtained from C57BL/6 skin 2 h after UVB irradiation (400 J per m2) failed to induce CH and induced DNP-specific tolerance instead; by contrast, similar cells obtained from same or even higher dose (400 J per m2 and 1200 J per m2) UVB-exposed BALB/c skin induced vigorous CH, and no tolerance was detected. In both C57BL/6 and BALB/c mice, Ia+-depleted EC/DNP neither sensitized naive syngeneic mice nor induced tolerance. LC/DNP prepared from unirradiated trunk skin of either C57BL/6 or BALB/c mice and pre-incubated in vitro for 2 h with cis-UCA, TNF-alpha, or IL-10 failed to induce intense CH; instead, all induced DNP-specific tolerance. Pre-incubation of similar LCs with alpha-MSH in vitro for 2 h also failed to induce CH but did not cause tolerance. Thus, single low-dose UVB irradiation alters the immunogenic and tolerogenic potentials of LCs only in UVB-susceptible mice; by contrast, pre-treatment of LCs with UVB-dependent soluble factors can achieve effects similar to UVB irradiation in both UVB-susceptible and -resistant strains of mice. These findings demonstrate that UVB susceptibility in mice may be determined by the production of UVB-dependent soluble factors within UVB-irradiated skin.

Structural organization and promoter analysis of murine heat shock transcription factor-1 gene

Heat shock factor-1 (HSF-1) activates transcription of heat shock proteins in eukaryotes. Several overlapping genomic clones containing the murine HSF-1 gene were isolated from a phage genomic library. Results indicate that the HSF-1 gene contains 13 exons that span at least 30 kilobase pairs. Sequence analysis of the 5'-untranslated region of HSF-1 suggests that it contains sequences of a recently described Bop1 gene in reverse orientation within its first 331 base pairs (bp) upstream of the translation initiation site. The minimal promoter sequence required for HSF-1 basal expression was identified by deletion analysis from -4 kilobase pairs to -331 bp of the promoter fused to a luciferase reporter gene using transient transfection assays. Results indicate that 331 bp upstream of the HSF-1 translation start site is required for maximal basal expression in NIH3T3 and F9 cells. This fragment also results in high levels of luciferase activity in the reverse orientation, that is, 5' to the Bop1 gene, suggesting that this segment is bidirectional and could be utilized for basal expression of both HSF-1 and Bop1 genes. This segment of the promoter contains recognition elements for Sp1 and CCAAT-box binding transcription factors, which when mutated in either sense or antisense orientations to the HSF-1 gene results in a reduction of basal expression by 50-75% relative to wild type, suggesting that these sites are critical for basal expression of both HSF-1 and Bop1 genes.