Inhibition of APE1/Ref-1 redox activity rescues human retinal pigment epithelial cells from oxidative stress and reduces choroidal neovascularization.

The effectiveness of current treatment for age related macular degeneration (AMD) by targeting one molecule is limited due to its multifactorial nature and heterogeneous pathologies. Treatment strategy to target multiple signaling pathways or pathological components in AMD pathogenesis is under investigation for better clinical outcome. Inhibition of the redox function of apurinic endonuclease 1/redox factor-1 (APE1) was found to suppress endothelial angiogenesis and promote neuronal cell recovery, thereby may serve as a potential treatment for AMD. In the current study, we for the first time have found that a specific inhibitor of APE1 redox function by a small molecule compound E3330 regulates retinal pigment epithelium (RPEs) cell response to oxidative stress. E3330 significantly blocked sub-lethal doses of oxidized low density lipoprotein (oxLDL) induced proliferation decline and senescence advancement of RPEs. At the same time, E3330 remarkably decreased the accumulation of intracellular reactive oxygen species (ROS) and down-regulated the productions of monocyte chemoattractant protein-1 (MCP-1) and vascular endothelial growth factor (VEGF), as well as attenuated the level of nuclear factor-κB (NF-κB) p65 in RPEs. A panel of stress and toxicity responsive transcription factors that were significantly upregulated by oxLDL was restored by E3330, including Nrf2/Nrf1, p53, NF-κB, HIF1, CBF/NF-Y/YY1, and MTF-1. Further, a single intravitreal injection of E3330 effectively reduced the progression of laser-induced choroidal neovascularization (CNV) in mouse eyes. These data revealed that E3330 effectively rescued RPEs from oxidative stress induced senescence and dysfunctions in multiple aspects in vitro, and attenuated laser-induced damages to RPE-Bruch׳s membrane complex in vivo. Together with its previously established anti-angiogenic and neuroprotection benefits, E3330 is implicated for potential use for AMD treatment.

Three to four-year-old nonpassaged EGF-responsive neural progenitor cells: proliferation, apoptosis, and DNA repair.

Epidermal growth factor responsive (EGFr) neural progenitor (NP) cells have been shown to be a potential alternative tissue source for neural transplantation and for developmental study. We have shown that nonpassaged EGFr NP cells can self-renew for 2 years in neurospheres and can robustly differentiate into glia and a number of neuronal cell types. We are now attempting to investigate if the EGFr NP cells will die or continue to live beyond the life span of the donor. In addition, we and other investigators have also found that EGFr NP cells, after transplant, retain only a small number of cells in the transplant site. In this study, we investigate the plasticity and fate of the EGFr NP cells. Using the nonpassaged method, we found EGFr NP cells live in the EGF supplement medium for over 4 years-the longest-lived EGFr NP cells ever reported. The 4-year-old striatal or cortical EGFr neurospheres, when subplated with substrate coating, migrate out of neurospheres and have robust growth with many processes. Furthermore, when nucleotide marker bromodeoxyuridine (BrdU) was added 3 days prior to the subplating, the EGFr NP cells were labeled positively with BrdU in the nucleus, indicating active proliferation activity. Meanwhile two other events were also found in the long-term EGFr NP cells. In the midst of the proliferation, apoptosis occurred. A subpopulation of EGFr NP cells are undergoing programmed cell death as indicated by the cell morphology and the TUNEL staining for DNA strand breaks. The TUNEL fluorescein-staining indicates that over 50% of EGFr NP cells are positive in the nuclei. On the other hand, we have also found that the major base excision repair enzyme, APE/ref-1, which is responsible for recognizing and repairing baseless sites in DNA, was present in the progenitor cells. However, in those cells undergoing apoptosis, APE/ref-1 levels were dramatically reduced or missing, and only a small percentage of cells were TUNEL and APE/ref-1 positive. These observations indicate that EGFr neural progenitor cells can live beyond the life span of the donor animal. The longevity of these cells in culture may be enhanced due to decreased apoptosis and the retention of normal DNA repair capacity.

Ethanol, growth hormone and testosterone in peripubertal rats.

The deleterious effects of ethanol on the hypothalamic pituitary growth hormone axis in adult male humans and animals have been well documented. It is also well established that ethanol has toxic effects on testicular function in adult humans and animals. Much less is known, however, about the effects of ethanol on the growth hormone (GH) axis and testicular function in adolescence. Recent studies have established that adolescent problem drinking is a widespread and growing threat to the health of young people in the United States. In the present study, therefore, we investigated if acute ethanol exposure in peripubertal male Sprague-Dawley rats altered normal pituitary and testicular function. Serum levels of GH and testosterone were measured at 1.5, 3, 6, and 24 h after a single i.p. injection of either saline or 3 g/kg body weight ethanol. Histologic analysis as well as serum testosterone levels allowed us to assign animals to either early puberty (35-day-old animals), mid-puberty (41-day-old animals), or young adult (51- and 66-day-old animals) status. Ethanol produced significant decrements in serum testosterone in the 51- and 66-day-old animals, with a trend toward suppression in the 41-day-old group. Furthermore acute ethanol administration significantly decreased serum GH (P < 0.0001 by 3 way ANOVA) demonstrating a significant effect of ethanol on serum GH in all age groups and at all time points studied when compared with saline injected controls (P < 0.01 by Turkey's studentized range test). Despite this significant fall in peripheral GH levels, there was no decrease in either GH mRNA or growth hormone-releasing factor (GRF) mRNA levels nor in hypothalamic concentration of GRF peptide. We conclude that, as in adult animals, acute exposure to ethanol causes a prolonged and severe decrement in serum GH which is possibly mediated at the level of secretion. In addition, there is attenuation in testosterone secretion. These data are all the more important since GH and testosterone play critical roles in organ maturation during this stage of development.

Ethanol-induced alterations in the posttranslational processing, but not secretion of luteinizing hormone-releasing hormone in vitro.

The effects of ethanol (EtOH) on the male hypothalamic pituitary reproductive axis are multiple and varied. Although direct gonadal toxicity has been reported, hypothalamic-pituitary perturbations have also been noted. The difficulty of sampling the hypothalamus has made direct investigation of EtOH-induced alterations on luteinizing hormone-releasing hormone (LHRH) fraught with interpretation problems. To circumvent this, we have conducted a series of experiments exploring the effect of 200 mg% EtOH in vitro on GT1-7 cells, a newly developed LHRH secreting neural cell line. Cell lines were treated with EtOH-containing or EtOH-free media for 2, 6, 24, or 48 hr. EtOH caused no significant change in LHRH secretion at any time point, although there was a trend to increased secretion after 2 hr EtOH exposure when compared with control. Significantly increased total (i.e., cellular plus secreted) pro-LHRH coupled with significantly reduced cellular LHRH after 6 hr only of EtOH exposure suggested that EtOH caused a transient decrease in processing from bioinactive pro-LHRH to bioactive LHRH. However, even at this time point, LHRH secretion from these EtOH-exposed cells was no different than from control cells. Steady-state LHRH mRNA levels were not changed by EtOH at any time point. These findings are concordant with previous in vitro data using hypothalamic tissue that has similarly demonstrated no effect of EtOH on LHRH secretion. Taken together with the in vivo demonstration that EtOH reduces hypothalamic-pituitary portal blood levels of LHRH, these data indicate that EtOH exerts its effect either at an extrahypothalamic locus and/or on non-LHRH-producing cells within the hypothalamus.

The effect of castration on steady state levels of luteinizing hormone-releasing hormone (LHRH) mRNA and proLHRH processing: time course study utilizing semi-quantitative reverse transcription/polymerase chain reaction.

Many studies have consistently shown that castration induces a prompt increase in serum levels and pituitary content of the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), as well as a concomitant rise in steady state levels of the messenger RNAs directing their synthesis. The reports of effects of castration on the overall physiology of hypothalamic luteinizing hormone-releasing hormone (LHRH)--steady state levels of LHRH mRNA, post-translational processing and secretion--have, however, not been consistent. The goal of the studies reported here was to provide the first analysis of the effect of castration, at multiple postoperative time points, on steady state levels of LHRH mRNA and on the levels of hypothalamic proLHRH. All these data are correlated with hypothalamic levels of the mature LHRH decapeptide and with serum and pituitary levels of immunoreactive LH and FSH. Adult male rats were either castrated or sham-castrated (controls) and then sacrificed at 1, 3, 5, 7, 14, 21 or 28 days postoperatively. As expected, there was a prompt and sustained rise in serum immunoreactive LH and FSH in castrates compared with sham-operated animals. Intra-pituitary LH levels rose above levels in the sham-operated animals by 14 days post castration. Intra-pituitary FSH showed a biphasic response, first falling significantly below control levels, then rising above control levels at 21 days. Steady state levels of LHRH mRNA in castrates, measured by reverse transcription/polymerase chain reaction, were increased about 2-fold above control levels by 1 day postoperatively, but were virtually identical to control levels at each of the other time points despite marked changes in the gonadotropins. ProLHRH content in castrates was 1.8-times that seen in controls at 1 day post castration (P<0.05), concomitant with the rise in steady state levels of LHRH mRNA at that time point. However, proLHRH content in castrates was no different from that seen in controls at each of the later time points examined. LHRH content was unchanged through 7 days after castration, but then fell significantly to 57% of control levels in hypothalami from animals gonadectomized 14 to 21 days previously (P<0.001 vs control), and to 54% of sham-operated levels at 28 days postoperatively (P<0.001). We conclude that: (1) changes in steady state levels of LHRH mRNA after castration are small and transient and (2) increased proLHRH coupled with unchanged LHRH levels at 1 day post castration, and castrate animal proLHRH at control levels coupled with falling LHRH at later post-castration time points indicate that the effect of gonadectomy on post-translational processing of proLHRH to LHRH is, likewise, small and transient. In aggregate our data suggest that most of the increase in serum LH and FSH seen in male rats after castration is not mediated at the hypothalamic level.

Expression of a multifunctional DNA repair enzyme gene, apurinic/apyrimidinic endonuclease (APE; Ref-1) in the suprachiasmatic, supraoptic and paraventricular nuclei.

Apurinic/apyrimidinic endonuclease (APE; also referred to as Ref-1) repairs oxidative damage to DNA and regulates the redox state of DNA binding proteins. This later property influences the ability of DNA binding proteins, which include Fos and Jun, to bind to AP-1 complexes. Since DNA binding proteins may play important roles in regulating neuronal activity in the hypothalamus, we examined the expression of APE in the hypothalami of rats. In situ hybridization studies revealed high levels of APE mRNA expression in the suprachiasmatic nuclei (SCN), supraoptic nuclei (SON) and paraventricular nuclei (PVN). Since the SCN are the site of a biological clock, we examined whether APE gene expression was regulated by the circadian cycle or by light. Quantitative in situ hybridization studies showed that APE mRNA levels remained constant over the circadian cycle and were not increased by light exposure at night. We also tested if APE expression was under osmotic control in the SON and PVN. Hypertonic stimulus, however, did not induce further expression of APE mRNA in either the SON or the PVN. These findings identify the SCN, SON and PVN as sites of high level APE gene expression. These data suggest that APE may play an important role in these structures either to facilitate DNA repair or DNA binding protein action.

Luteinizing hormone-releasing hormone (LHRH) in rat prostate: characterization of LHRH peptide, messenger ribonucleic acid expression, and molecular processing of LHRH in intact and castrated male rats.

Continuous administration of LHRH agonist suppresses the pituitary-gonadal axis, achieving chemical castration. Thus, LHRH agonist has been used as an alternative (to surgical castration) for the treatment of steroid-dependent prostate cancer. However, recent reports have demonstrated that LHRH agonist had a direct inhibiting effect on prostate cancer cell proliferation and that cancerous prostate tissue contained a LHRH-like peptide. In this paper we are reporting for the first time that the normal rat ventral prostate contained immunoactive and bioactive LHRH as well as its precursor molecule, pro-LHRH. Our investigation showed that the LHRH concentration in prostate increased 2 weeks after castration from 1.68 +/- 0.09 to 3 +/- 0.2 pg/mg tissue (P < 0.001). At the same time, the concentration of pro-LHRH decreased from 149 +/- 6.5 to 68 +/- 6.8 pg/mg tissue (P < 0.001). Furthermore, intact rat prostate expressed LHRH mRNA, which increased 13-fold 2 weeks after castration. In summary, the prostate of intact Sprague-Dawley rats has the capacity to produce the LHRH precursor and process it to the mature decapeptide, and this production/processing increases significantly after castration.

Coupled reverse transcription-polymerase chain reaction (RT-PCR) technique is comparative, quantitative, and rapid: uses in alcohol research involving low abundance mRNA species such as hypothalamic LHRH and GRF.

The measurement of alterations in low abundance mRNAs such as the hypothalamic hormones luteinizing hormone-releasing hormone (LHRH) and growth hormone-releasing hormone (GHRH or GRF) from individual hypothalamic tissues in rats has previously been difficult and usually required either isolation of poly(A) mRNA or the pooling of numerous animals to obtain a reasonable signal on Northern blots. Although more sensitive detection methods exist, such as the use of RNA probes or solution hybridization (RNase protection), we have found the most reliable, sensitive, rapid, and accurate method is the reverse transcription-polymerase chain reaction (RT-PCR) using histone H3.3 as an internal control for both steps of this procedure. H3.3 is a cell-cycle independent and constitutively expressed gene in all tissues. We have developed an RT-PCR assay for LHRH and GRF mRNA quantitation and comparative analysis for hypothalamic and extrahypothalamic brain tissues and present the use of RT-PCR for LHRH quantitation in ethanol (EtOH) studies.

The effect of acute in vivo ethanol exposure on follicle stimulating hormone transcription and translation.

The impact of ethanol (EtOH) on male rodent reproduction has been well characterized for luteinizing hormone (LH) with suppression of LH release from the pituitary being reported. We have previously reported that acute ethanol (EtOH) exposure in vivo results in rapid and marked suppression of beta-LH gene expression and protein release from the pituitary. This suppression of beta-LH gene expression was unaccompanied by a change in the common alpha-subunit mRNA. To further explore the impact of ethanol on male rodent reproduction, we have expanded our studies to follicle stimulating hormone (FSH) and hypothalamic luteinizing hormone releasing hormone (LHRH) as well as of pituitary protein kinase C (PKC). Previously castrated male rats were acutely exposed to EtOH and a dramatic reduction in both serum FSH and LH levels was noted at 1.5 and 3 hr after treatment. These levels returned to saline injected control values at 6 and 24 hr. Despite the fall in serum FSH, there was no change in intrapituitary FSH content at any time point; this lack of pituitary FSH depletion in the face of a fall in serum levels is suggestive of impaired FSH release. In contrast to the fall in beta-LH steady-state mRNA levels seen previously and confirmed in the present studies, there was no change in beta-FSH steady-state mRNA at any time point suggesting that EtOH has dichotomous effects on the expression of these two gonadotropins. Pituitary PKC levels were also assessed and found to be unaffected by EtOH at any time point.(ABSTRACT TRUNCATED AT 250 WORDS)

The rat prolactin gene is expressed in brain tissue: detection of normal and alternatively spliced prolactin messenger RNA.

Previous work by our laboratory has described the presence and widespread distribution of a PRL-like immunoreactive protein in brain. The persistence of this PRL in brain after hypophysectomy provided substantial evidence that brain PRL represented the product of a synthetic pool separate from that of the anterior pituitary PRL. To pursue this concept of independent synthesis further, we sought to determine whether brain tissue expressed PRL mRNA. Although we were easily able to detect a single species of PRL mRNA in pituitary by Northern hybridization, we could not visualize message in hypothalamus or extrahypothalamic brain by this technique. Therefore, we performed the polymerase chain reaction on cDNAs from anterior pituitary, hypothalamus, discrete extrahypothalamic brain regions, and other tissues. Hypothalamus and extrahypothalamic brain parts, including the cerebellum, caudate, brain stem, amygdala, thalamus, cortex, and hippocampus, were all positive to varying degrees. Lung and liver were negative, and anterior pituitary was consistently positive. All positive tissues, including anterior pituitary, expressed two hybridization signals: the expected amplified product and another smaller one. The smaller amplified product is presumably the result of an alternatively spliced transcript that is missing part of the PRL gene. Hypophysectomized animals did not express PRL message in brain, but expression was restored in hypophysectomized animals treated with testosterone. Transcripts for Pit-1 (GHF-1), a transcription factor important in regulation of pituitary PRL, were not detected in hypothalamus or any of the extrahypothalamic brain parts. The finding of testosterone stimulation of brain PRL message and undetectable levels of Pit-1 (GHF-1) in hypothalamic and extrahypothalamic brain regions indicates that the transcriptional regulation of PRL in the brain is different from that in the anterior pituitary.

Presence of luteinizing hormone-releasing hormone (LHRH) mRNA in rat spleen lymphocytes.

Pursuant to our report of an immunoreactive and bioactive luteinizing hormone-releasing hormone (LHRH)-like molecule in rat spleen lymphocytes, we sought to determine whether these cells were capable of synthesizing LHRH by determining whether lymphocytes contain LHRH mRNA. To do this, total RNA was extracted from hypothalamic tissue, anterior pituitaries and from lymphocytes, and then this was reverse transcribed to cDNA and amplified via the polymerase chain reaction (PCR) utilizing synthetic oligonucleotides bracketing a portion of the LHRH gene. Following gel electrophoresis a discrete band of the expected size of 375 base pairs was found in the hypothalamus (positive control), and in lymphocytes, but not in the anterior pituitary (negative control). Furthermore, after Southern blotting, a 32P-labelled LHRH cDNA, hybridized to the 375 base pair, was amplified in hypothalamus fragments and in lymphocytes, but not in anterior pituitary tissue. These data strongly suggest that LHRH, in addition to being an important neuropeptide, is an immune cell synthesized immunomodulator.

Cross-reaction of albumin with polyclonal LH antibody on western blots.

When pituitary tissue was subjected to Western blot analysis utilizing polyclonal antibody NIDDK-rLH-S-10, bands at 17 and 19 Kd representing LH subunits were identified. In addition, a high molecular weight 66 Kd band was seen. Surprisingly this high molecular weight band was also seen in rat cerebral cortex, brain stem, hypothalamus, spinal cord, lung, liver, pancreas, spleen, kidney, testis, and serum. Antibody preabsorbed with iodination grade rat LH antigen no longer recognized the 17 and 19 Kd bands in pituitary, but recognized the 66 Kd bands in pituitary and the other tissues examined. Since 66 Kd is the molecular weight of albumin, we found that antisera to rat albumin recognized this same high molecular weight band in the tissues examined. Preabsorption of LH antibody with albumin reduced the ability of that antibody to recognize this 66 Kd. A monoclonal antibody to bovine LH beta-subunit recognized only the LH protein in anterior pituitary, but no high molecular weight band in either pituitary or the other tissues studied. Finally, 10, 100, and 1000 micrograms of rat albumin caused no substantial interference under conditions of RIA. We conclude that the polyclonal antibody, provided by the NIH, is excellent for conditions of RIA, but caution must be exercised when it is used for Western analysis where some lots of this antibody may recognize other unrelated proteins.