Regulation of cytochrome P-450 messenger RNA and apoprotein levels by heme

2-Allylisopropylacetamide, a porphyrinogen which decreases the microsomal and cytosolic heme pools, is a phenobarbitone-like inducer of cytochrome P-450(b + e) messenger RNAs in rat liver. The porphyrinogen, however, does not affect the nuclear heme pool and enhances the transcription of cytochrome P-450(b + e) messenger RNAs strikingly. Inhibitors of heme biosynthesis, such as CoCl2 and 3-amino-1,2,4-triazole, which decrease the total heme levels including that of the nuclear heme pool, block the 2-allylisopropylacetamide- or phenobarbitone-mediated increase in the transcription of cytochrome P-450(b + e) messenger RNAs. Administration of exogenous heme at a very low concentration (25 μg/100 g) is able to counteract the inhibitory effects of the heme biosynthetic inhibitors. Addition of heme in vitro to heme-depleted nuclei leads to a significant increase in the transcription rates for cytochrome P-450(b + e) messenger RNAs. 2-Allylisopropylacetamide, unlike phenobarbitone, fails to increase the levels of cytochrome P-450b protein at 12 h after the drug administration, although there is a striking increase in the messenger RNA levels. Under conditions of 2-allylisopropylacetamide treatment, the cytochrome P-450 messenger RNA is translated, but the newly synthesized apoprotein undergoes rapid degradation. It is concluded that heme is a positive modulator of cytochrome P-450 gene transcription and is also required to stabilize the freshly synthesized apoprotein

Reducing Amyloid Plaque Burden via Ex Vivo Gene Delivery of an Aβ-Degrading Protease: A Novel Therapeutic Approach to Alzheimer Disease

Matthew Hemming and colleagues describe the ex vivo gene delivery of an Aβ-degrading protease that reduces amyloid plaque burden in transgenic mice expressing human amyloid precursor protein

Molecular characterization of SMILE as a novel corepressor of nuclear receptors

SMILE (small heterodimer partner interacting leucine zipper protein) has been identified as a coregulator in ER signaling. In this study, we have examined the effects of SMILE on other NRs (nuclear receptors). SMILE inhibits GR, CAR and HNF4α-mediated transactivation. Knockdown of SMILE gene expression increases the transactivation of the NRs. SMILE interacts with GR, CAR and HNF4α in vitro and in vivo. SMILE and these NRs colocalize in the nucleus. SMILE binds to the ligand-binding domain or AF2 domain of the NRs. Competitions between SMILE and the coactivators GRIP1 or PGC-1α have been demonstrated in vitro and in vivo. Furthermore, an intrinsic repressive activity of SMILE is observed in Gal4-fusion system, and the intrinsic repressive domain is mapped to the C-terminus of SMILE, spanning residues 203–354. Moreover, SMILE interacts with specific HDACs (histone deacetylases) and SMILE-mediated repression is released by HDAC inhibitor trichostatin A, in a NR-specific manner. Finally, ChIP (chromatin immunoprecipitation) assays reveal that SMILE associates with the NRs on the target gene promoters. Adenoviral overexpression of SMILE represses GR-, CAR- and HNF4α-mediated target gene expression. Overall, these results suggest that SMILE functions as a novel corepressor of NRs via competition with coactivators and the recruitment of HDACs

Analysis of neuropeptide gene expression by transfection of DNA into cell lines

The transcriptional regulation of neuropeptide genes by cAMP is often directed by a cAMP responsive enhancer (CRE) upstream to the promoter of the genes. The identity of the CRE was determined by transient transfection experiments and has the consensus sequence of 5′-TGACGTCA-3′. A large family of transcription factors have been identified which recognize the CRE. Transient transfection assays that employed expression of these factors driven by viral promoters have determined they can transactivate the neuropeptide gene promoters. Because of the large number of factors that have been identified as being able to recognize the CRE, it has been difficult to determine which factors mediate in vivo the transactivation of a particular CRE. Using a dominant negative mutant of one of these factors, CREB, it has been determined that both CREB as well as other factors which do not interact with CREB may mediate the cAMP response of the somatostatin gene.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43232/1/11022_2005_Article_BF01667368.pd

Developmental regulation of cytochrome P-450 (b+e) and glutathione transferase (Ya+Yc) gene expression in rat liver

The expression of cytochrome P-450 (b+e) and glutathione transferase (Ya+Yc) genes has been studied as a function of development in rat liver. The levels of cytochrome P-450 (b+e) mRNAs and their transcription rates are too low for detection in the 19-day old fetal liver before or after phenobarbitone treatment. However, glutathione transferase (Ya+Yc) mRNAs can be detected in the fetal liver as well as their induction after phenobarbitone treatment can be demonstrated. These mRNAs contents as well as their inducibility with phenobarbitone are lower in maternal liver than that of adult nonpregnant female rat liver. Steroid hormone administration to immature rats blocks substantially the phenobarbitone mediated induction of the two mRNA families as well as their transcription. It is suggested that steroid hormones constitute one of the factors responsible for the repression of the cytochrome P-450 (b+e) and glutathione transferase (Ya+Yc) genes in fetal liver

Outcome Measurements in Chronic Neuropathic Pain Patients Receiving Multiple Rounds of Ketamine Infusions.

Background: Chronic neuropathic pain is known to impact many aspects of quality of life (QOL). Ketamine, a phenycyclidine derivative with both anesthetic and analgesic properties, has been previously shown to provide relief in patients receiving outpatient infusions of the drug. Objective: To assess the effect of outpatient ketamine infusions on QOL outcome measurements in patients with chronic neuropathic pain who have received several rounds of ketamine infusions. Methods: Patients with chronic neuropathic pain were asked to complete the brief pain inventory (BPI) concerning the impact of their chronic pain on aspects of their QOL (overall daily pain score, general activity, walking, work, relationship with others, sleep, and enjoyment of life) before receiving ketamine infusion and two to four weeks after the ketamine infusions at the follow up clinic visit. The patients ranked the impact of pain on QOL, from a scale of zero (no impact) to ten (severely impacts). Overall change in QOL both prior to treatment with ketamine infusion and after administration were evaluated. Four predictors (age, sex, race, and BMI) were also used in order to evaluate any change on QOL due to demographics. Only patients who received more than one infusion were included in the study. Results: There were 34 patients in the sample, with mean age 43.0 (SD 12.8), mean BMI 26.0 (SD 8.2), 68% female, 74% white, 18% black, and 9% other or unknown race. 11 patients had 2 episodes of ketamine infusion, 6 had 3 episodes, and the remaining 17 patients had between 4 and 19 episodes (median number of episodes = 3.5). The model predicting mean BPI score pre-infusion (using each subject’s first episode of ketamine infusion only), was significant (p=.036), indicating a significant effect with moderate effect size. The only predictor with a significant independent association with mean BPI pre-infusion was pain (p=.0042). The model predicting post-infusion mean BPI score was not significant (p=.59). In the model predicting change from pre to post-infusion in mean BPI score at episode 1, the only significant predictor was BMI (p=.041). In the mixed model predicting pre-infusion mean BPI across repeated episodes of ketamine infusion, there was a significant episode effect (p=.029). After adjusting for covariates, the mean pre-infusion BPI scores at episodes 2 through 15 are not significantly different from episode 1, but starting with episode 16, all later episodes have significantly lower pre-infusion BPI scores than episode 1. In the model predicting the pattern of pre-infusion BPI scores across episodes, there was a significant interaction by age (p=.016), with older patients have reduced pre-infusion BPI scores at episodes 5 & 12, compared with younger patients. Conclusion: Expanding upon our previous study, we examined QOL outcomes for returning ketamine infusion patients with chronic neuropathic pain based on their BPI scores. Ketamine infusions were found to continuously improve patient’s pain scores over multiple rounds of infusion. Ketamine infusions were also found to have greater affect in older patients as well as patients with a greater BMI. However, other predictors or QOL were not found to be significantly different

Regulation of cytochrome P-450 messenger RNA and apoprotein levels by heme

2-Allylisopropylacetamide, a porphyrinogen which decreases the microsomal and cytosolic heme pools, is a phenobarbitone-like inducer of cytochrome P 4504(b+e) mRNAs in rat liver. The porphyrinogen, however, does not affect the nuclear heme pool and enhances the transcription of cytochrome P 450(b+e) mRNAs strikingly. Inhibitors of heme biosynthesis, such as $CoCl_2$ and 3-amino-1,2,4-triazole, which decrease the total heme levels including that of the nuclear heme pool, block the 2-allylisopropylacetamide- or phenobarbitone-mediated increase in the transcription of cytochrome P 450(b+e) mRNAs. Administration of exogenous heme at a very low concn. (25 \mug/100 g) is able to counteract the inhibitory effects of the heme biosynthetic inhibitors. Addn. of heme in vitro to heme-depleted nuclei leads to a significant increase in the transcription rates for cytochrome P 450(b+e) mRNAs. 2-Allylisopropylacetamide, unlike phenobarbitone, fails to increase the levels of cytochrome P-450b protein at 12 h after the drug administration, although there is a striking increase in the mRNA levels. Under conditions of 2-allylisopropylacetamide treatment, the cytochrome P 450 mRNA is translated, but the newly synthesized apoprotein undergoes rapid degrdn. Thus, heme is a pos. modulator of cytochrome P 450 gene transcription and is also required to stabilize the freshly synthesized apoprotei