Abstract P2-06-03: Insulin receptor isoform signaling in breast cancer

Recent data shows that insulin receptor (IR) and the type I insulin-like growth factor receptor (IGF1R) play important roles in breast cancer cell biology. Targeting only IGF1R has not been successful perhaps due to compensation by IR. IR exists in two isoforms, fetal isoform IR-A is a splice variant of IR which excludes exon 11. The adult/metabolic isoform IR-B is the predominant species expressed in normal tissues, while the fetal form IR-A is more highly expressed in breast cancer. IR-A mRNA in endocrine resistant cells is expressed at levels 24-fold higher than IGF1R expression (Gradishar, et al. Clin Cancer Res 22:301 2016 PMID: 26324738). In addition to its homodimer, IR-A can also dimerize with IGF1R to form a hybrid. Homodimer IR-A responds to IGF-II and insulin, while IGF1R/IR-A hybrid can also respond to IGF-I. Previous studies in our lab showed down regulation of IGFIR increases the sensitivity of breast cancer cells to insulin. To further investigate the roles of IR-A and IR-B in breast cancer biology, we cloned IR-A and IR-B isoforms into pLV-mCherry and pLJM1EGFP lentiviral expression vectors. Then MCF-7L breast cancer cells were infected with IR-A, IR-A vector control, IR-B and IR-B vector control. Both pooled and single clones were studied. Our results showed that both IR-A and IR-B were highly expressed in MCF-7L cells with the introduced IR tagged species present at a higher molecular weight confirmed by immunoprecipitation and immunoblot. The lower migrating species was endogenous IR. IR-A-pool/Clones had strong basal IR tyrosine phosphorylation, while IR-B-pool/clones did not. This basal phosphorylation did not activate downstream signaling as measured by pAKT and pErk1,2. IR-A basal phosphorylation was completely inhibited by BMS754807 (0.3μM), a dual IGFIR/IR tyrosine kinase inhibitor. Total levels of IRS1, IRS2, IGF1R, ERa, AKT and Erk1,2 levels were not changed in the over-expressing cells. Ligands-IGF-I (5nM), IGF-II (10nM) and Insulin (10nM) stimulated IGF1R/IR, IRS, AKT and Erk1,2 phosphorylation in IR-A-pool and high expression clone IR-A-G5. Cells expressing IR-A activated downstream signaling (IRS, AKT and Erk1,2) at 0.1nM insulin, while IR-A vector control cells required 1nM insulin. IR-B-pool overexpressing cells were not more sensitive to insulin compared to parental cells. Insulin significantly increased Erk1,2 phosphorylation in IR-A-G5 cell while IGF-I stimulation was minimal. In contrast, Erk1,2 phosphorylation in parental cells and vector control cells was primarily mediated by IGF-I, not insulin. IR-A overexpressing cells were stimulated in monolayer growth by insulin. These data show that IR-A expression, as seen in endocrine resistant breast cancer cells, sensitizes breast cancers to low concentrations of insulin. Thus, IR-A expression could serve as a target in breast cancer.

Citation Format: Zhang X, Chan JY, Pan Y, Dong C, Yee D. Insulin receptor isoform signaling in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-03.

Abstract P1-05-03: Isoform specific targeting of insulin receptor

The insulin receptor (InsR) exists in both an A and B isoform. InsR-B differs from InsR-A by the inclusion of exon 11, which encodes 12 amino acid residues at the C-terminus of the InsR alpha-subunit. Increased InsR-A expression is associated with mitogenic signaling pathways while InsR-B is linked to insulin-mediated metabolic functions. Predominant InsR-A expression may therefore be important in growth and fetal development of embryos, whereas predominant InsR-B expression has a role in metabolic insulin action in adult life. Increased InsR-A expression is seen in breast cancer. In endocrine resistant breast cancer, InsR-A is expressed at high levels (Gradishar, et al. Clin Cancer Res 22:301 2016 PMID: 26324738). Thus, developing InsR-A specific inhibitors could be a useful therapy for breast cancer. We have previously published InsR specific binders using a T7 phage gene 2 protein (Gp2), a small protein scaffold (Chan, et al. Mol Cancer Ther 16:1324 2017 PMID: 28468775), with the long-term goal of creating effective InsR inhibitors and diagnostics. Using yeast display and directed evolution, we identified three Gp2 variants (Gp2 #1, #5, and #10) with low nanomolar affinity and specific binding to cell surface InsR. We have shown that these Gp2 variants inhibited insulin-mediated monolayer proliferation in both endocrine-sensitive and resistant breast cancer, but did not downregulate InsR expression. To further characterize the specificity of Gp2 variants, we used two techniques. HEK293T cells were infected with lentiviral vectors expressing either InsR-A tagged with mCherry or InsR-B tagged with eGFP. Using these cells, we performed “mock panning” and showed the Gp2 #5 variant bound both InsR-A and InsR-B, but had higher affinity for InsR-B. We also incorporated Gp2 #5 into the capsid of a tropism-null adeno-associated virus (AAV). Using this Gp2-AAV, we infected HEK293T-InsR-A or InsR-B cells at a number of different multiplicities of infection. These data were consistent with panning data and showed specific Gp2-AAV infection of cells expressing high levels of InsR-B, but not InsR-A. Thus, our data show that Gp2 variants we created have a higher affinity for InsR-B than InsR-A. Despite this preferred affinity, these Gp2 binders have sufficient binding to InsR-A to disrupt the biological effects of insulin in breast cancer cells. Thus, even relatively low affinity binding to InsR-A can disrupt its function. Further development of InsR-A Gp2 binders may be developed and provide more specific targeting of the breast cancer specific isoform of InsR.

Citation Format: LaPara K, Chan JY, Zdechlik A, Ljunggren K, Schmidt D, Hackel B, Yee D. Isoform specific targeting of insulin receptor [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-05-03.

Evidence against a role for NLRP3-driven islet inflammation in db/db mice

Objectives

Type 2 diabetes (T2D) is associated with chronic, low grade inflammation. Activation of the NLRP3 inflammasome and secretion of its target interleukin-1β (IL-1β) have been implicated in pancreatic β cell failure in T2D. Specific targeting of the NLRP3 inflammasome to prevent pancreatic β cell death could allow for selective T2D treatment without compromising all IL-1β-associated immune responses. We hypothesized that treating a mouse model of T2D with MCC950, a compound that specifically inhibits NLRP3, would prevent pancreatic β cell death, thereby preventing the onset of T2D.

Methods

Diabetic db/db mice were treated with MCC950 via drinking water for 8 weeks from 6 to 14 weeks of age, a period over which they developed pancreatic β cell failure. We assessed metabolic parameters such as body composition, glucose tolerance, or insulin secretion over the course of the intervention.

Results

MCC950 was a potent inhibitor of NLRP3-induced IL-1β in vitro and was detected at high levels in the plasma of treated db/db mice. Treatment of pre-diabetic db/db mice with MCC950, however, did not prevent pancreatic dysfunction and full onset of the T2D pathology. When examining the NLRP3 pathway in the pancreas of db/db mice, we could not detect an activation of this pathway nor increased levels of its target IL-1β.

Conclusions

NLRP3 driven-pancreatic IL-1β inflammation does not play a key role in the pathogenesis of the db/db murine model of T2D.

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Inhibition of NLRP3 via MCC950 in db/db mice did not improve glucose tolerance.

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MCC950 treatment did not prevent beta cell loss of function.

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Expression of IL1beta and NLRP3 does not appear increased in db/db islets.

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We conclude against a role for NLRP3 in db/db pancreatic dysfunction.

Effects of unilateral internal jugular vein removal on intraocular pressure

PURPOSE

To investigate the intraocular pressure (IOP) and retinal nerve fibre layer (RNFL) thickness after ipsilateral neck dissection with internal jugular vein (IJV) removal for head and neck tumours.

METHODS

A computer search was performed to identify all patients who were treated with neck dissection with unilateral IJV removal from 2005 to 2012. All patients underwent a complete ophthalmological examination including measurement of IOP by Goldmann applanation tonometry and the average RNFL thickness using a Spectralis optical coherence tomography. The following analyses were made between the eyes on the side of the IJV removal versus the eye on the contralateral side: gonioscopy, IOP, vertical cup-disc ratio (VCDR) and peripapillary RNFL. Correlation analysis between the year of operation and IOP was done using the Pearson correlation coefficient.

RESULTS

This prospective cross-sectional study recruited 38 patients. The median age at operation was 59.5 years (range 33-87 years). There were 26 males and 12 females. Exactly half of the patients had left IJV removal and the remaining half had right IJV removal. The median interval from neck dissection to eye assessment was 46.5 months (range 11-97 months). There was no significant difference between the ipsilateral and contralateral side in terms of gonioscopy, IOP, VCDR, and RNFL. There was no significant correlation between the duration of IJV removal and IOP (p=0.8).

CONCLUSIONS

Ipsilateral IJV removal after neck dissection did not result in any significant differences in the average peripapillary RNFL thickness or IOP compared to the contralateral eye at a mean of 46.5 months postoperatively.

Characterization of novel akermanite:poly-ϵ-caprolactone scaffolds for human adipose-derived stem cells bone tissue engineering

In this study, three different akermanite:poly-ϵ-caprolactone (PCL) composite scaffolds (wt%: 75:25, 50:50, 25:75) were characterized in terms of structure, compression strength, degradation rate and in vitro biocompatibility to human adipose-derived stem cells (hASC). Pure ceramic scaffolds [CellCeram™, custom-made, 40:60 wt%; β-tricalcium phosphate (β-TCP):hydroxyapatite (HA); and akermanite] and PCL scaffolds served as experimental controls. Compared to ceramic scaffolds, the authors hypothesized that optimal akermanite:PCL composites would have improved compression strength and comparable biocompatibility to hASC. Electron microscopy analysis revealed that PCL-containing scaffolds had the highest porosity but CellCeram™ had the greatest pore size. In general, compression strength in PCL-containing scaffolds was greater than in ceramic scaffolds. PCL-containing scaffolds were also more stable in culture than ceramic scaffolds. Nonetheless, mass losses after 21 days were observed in all scaffold types. Reduced hASC metabolic activity and increased cell detachment were observed after acute exposure to akermanite:PCL extracts (wt%: 75:25, 50:50). Among the PCL-containing scaffolds, hASC cultured for 21 days on akermanite:PCL (wt%: 75:25) discs displayed the highest viability, increased expression of osteogenic markers (alkaline phosphatase and osteocalcin) and lowest IL-6 expression. Together, the results indicate that akermanite:PCL composites may have appropriate mechanical and biocompatibility properties for use as bone tissue scaffolds.

Cross-talk between the unfolded protein response and nuclear factor-κB signalling pathways regulates cytokine-mediated beta cell death in MIN6 cells and isolated mouse islets

AIMS/HYPOTHESIS

Pancreatic beta cell destruction in type 1 diabetes may be mediated by cytokines such as IL-1β, IFN-γ and TNF-α. Endoplasmic reticulum (ER) stress and nuclear factor-κB (NFκB) signalling are activated by cytokines, but their significance in beta cells remains unclear. Here, we investigated the role of cytokine-induced ER stress and NFκB signalling in beta cell destruction.

METHODS

Isolated mouse islets and MIN6 beta cells were incubated with IL-1β, IFN-γ and TNF-α. The chemical chaperone 4-phenylbutyric acid (PBA) was used to inhibit ER stress. Protein production and gene expression were assessed by western blot and real-time RT-PCR.

RESULTS

We found in beta cells that inhibition of cytokine-induced ER stress with PBA unexpectedly potentiated cell death and NFκB-regulated gene expression. These responses were dependent on NFκB activation and were associated with a prolonged decrease in the inhibitor of κB-α (IκBα) protein, resulting from increased IκBα protein degradation. Cytokine-mediated NFκB-regulated gene expression was also potentiated after pre-induction of ER stress with thapsigargin, but not tunicamycin. Both PBA and thapsigargin treatments led to preferential upregulation of ER degradation genes over ER-resident chaperones as part of the adaptive unfolded protein response (UPR). In contrast, tunicamycin activated a balanced adaptive UPR in association with the maintenance of Xbp1 splicing.

CONCLUSIONS/INTERPRETATION

These data suggest a novel mechanism by which cytokine-mediated ER stress interacts with NFκB signalling in beta cells, by regulating IκBα degradation. The cross-talk between the UPR and NFκB signalling pathways may be important in the regulation of cytokine-mediated beta cell death.

Functional hand proportion is approximated by the Fibonacci series

The debatable relationship of functional human hand proportion with the Fibonacci series has remained an obscure scientific enigma short of clinical interest. The main difficulty of proving such a relationship lies in defining what should constitute true functional proportion. In this study, we re-evaluate this unique relationship using hand flexion creases as anatomical surrogates for the functional axes of joint rotation. Standardised desktop photocopies of palmar views of both hands in full digital extension and abduction were obtained from 100 healthy male volunteers of Chinese ethnicity. The functional axes were represented by the distal digital crease (distal interphalangeal joint, DIPJ), proximal digital crease (proximal interphalangeal joint, PIPJ), as well as the midpoint between the palmar digital and transverse palmar creases (metacarpophalangeal joint, MCPJ). The ratio of DIPJ-Fingertip:PIPJ-DIPJ:MCPJ-PIPJ (p3:p2:p1) was measured by two independent observers and represented as standard deviation about the mean, and then compared to the theoretical ratio of 1:1:2. Our results showed that, for the 2nd to 5th digits, the p2:p3 ratios were 0.97 ± ± 0.09, 1.10 ± 0.10, 1.04 ± 0.12, and 0.80 ± 0.08, respectively; whilst the p1:p2 ratios were 1.91 ± 0.17, 1.98 ± 0.14, 1.89 ± 0.16, and 2.09 ± 0.24, respectively. When the data were analysed for all digits, they showed a combined p3:p2:p1 ratio of 1:0.98:2.01. In conclusion, our results suggest that functional human hand proportion, as defined by flexion creases, is approximated by the Fibonacci series.

Differential regulation of adaptive and apoptotic unfolded protein response signalling by cytokine-induced nitric oxide production in mouse pancreatic beta cells

AIMS/HYPOTHESIS

Pro-inflammatory cytokines such as IL-1β, IFN-γ and TNF-α may contribute to pancreatic beta cell destruction in type 1 diabetes. A mechanism requiring nitric oxide, which is generated by inducible nitric oxide synthase (iNOS), in cytokine-induced endoplasmic reticulum (ER) stress and apoptosis has been proposed. Here, we tested the role of nitric oxide in cytokine-induced ER stress and the subsequent unfolded protein response (UPR) in beta cells.

METHODS

Isolated islets from wild-type and iNos (also known as Nos2) knockout (iNos ( -/- )) mice, and MIN6 beta cells were incubated with IL-1β, IFN-γ and TNF-α for 24-48 h. N (G)-methyl-L: -arginine was used to inhibit nitric oxide production in MIN6 cells. Protein levels and gene expression were assessed by western blot and real-time RT-PCR.

RESULTS

In islets and MIN6 cells, inhibition of nitric oxide production had no effect on the generation of ER stress by cytokines, as evidenced by downregulation of Serca2b (also known as Atp2a2) mRNA and increased phosphorylation of PKR-like ER kinase, Jun N-terminal kinase (JNK) and eukaryotic translation initiation factor 2 α subunit. However, nitric oxide regulated the pattern of UPR signalling, which delineates the cellular decision to adapt to ER stress or to undergo apoptosis. Inhibition of nitric oxide production led to reduced expression of pro-apoptotic UPR markers, Chop (also known as Ddit3), Atf3 and Trib3. In contrast, adaptive UPR markers (chaperones, foldases and degradation enhancers) were increased. Further analysis of mouse islets showed that cytokine-induced Chop and Atf3 expression was also dependent on JNK activity.

CONCLUSIONS/INTERPRETATION

The mechanism by which cytokines induce ER stress in mouse beta cells is independent of nitric oxide production. However, nitric oxide may regulate the switch between adaptive and apoptotic UPR signalling.

Regulatory potential for concerted modulation of Nrf2- and Nfkb1-mediated gene expression in inflammation and carcinogenesis

Many studies have implicated nuclear factor E2-related factor 2 (Nrf2) and nuclear factor-kappaB1 (Nfkb1) in inflammation and cancer. However, the regulatory potential for crosstalk between these two important transcription factors in inflammation and carcinogenesis has not been explored. To delineate conserved transcription factor-binding site signatures, we performed bioinformatic analyses on the promoter regions of human and murine Nrf2 and Nfkb1. We performed multiple sequence alignment of Nrf2 and Nfkb1 genes in five mammalian species - human, chimpanzee, dog, mouse and rat - to explore conserved biological features. We constructed a canonical regulatory network for concerted modulation of Nrf2 and Nfkb1 involving several members of the mitogen-activated protein kinase (MAPK) family and present a putative model for concerted modulation of Nrf2 and Nfkb1 in inflammation/carcinogenesis. Our results reflect potential for putative crosstalk between Nrf2 and Nfkb1 modulated through the MAPK cascade that may influence inflammation-associated etiopathogenesis of cancer. Taken together, the elucidation of potential relationships between Nrf2 and Nfkb1 may help to better understand transcriptional regulation, as well as transcription factor networks, associated with the etiopathogenesis of inflammation and cancer.

Discovery of the Griffiths phase in the itinerant magnetic semiconductor Fe1-xCoxS2

Critical points that can be suppressed to zero temperature are interesting because quantum fluctuations have been shown to dramatically alter electron gas properties. Here, the metal formed by Co doping the paramagnetic insulator FeS2, Fe1-xCoxS2 is demonstrated to order ferromagnetically at x > xc = 0.01+/-0.005, where we observe unusual transport, magnetic, and thermodynamic properties. We show that this magnetic semiconductor undergoes a percolative magnetic transition with distinct similarities to the Griffiths phase, including singular behavior at xc and zero temperature.

Involvement of noradrenergic innervation from locus coeruleus to hippocampal formation in negative feedback regulation of penile erection in the rat

We demonstrated previously that a novel negative feed back mechanism for the regulation of penile erection, which is triggered by ascending sensory inputs initiated by tumescence of the penis, exists in the hippocampal formation (HF). This study further elucidated the role of the locus coeruleus (LC), which is the largest aggregate of norepinephrine-containing neurons in the brain and provides the major noradrenergic innervation to the HF, in this process. Adult male Sprague-Dawley rats that were anesthetized and maintained with chloral hydrate were used. The intracavernous pressure (ICP) recorded from the corpus cavernosum of the penis was used as the experimental index for penile erection. Electrical activation of the LC elicited a significant reduction in baseline ICP. Similar observations were obtained on microinjection bilaterally into the hippocampal CA1 or CA3 subfield or dentate gyrus of equimolar doses (5 nmol) of norepinephrine (alpha1-, alpha2-agonist), phenylephrine (alpha1-agonist), or BHT 933 (alpha2-agonist). Bilateral electrolytic lesions of the LC discernibly enhanced the magnitude and/or duration of the elevation in ICP induced by intracavernous administration of papaverine (400 microgram). A potentiation of the papaverine-evoked ICP increase was also observed following pretreatment with bilateral hippocampal application of equimolar doses (250 pmol) of either prazosin (alpha1-, alpha2B-, alpha2C-antagonist), naftopidil (alpha1A/D-antagonist), yohimbine (alpha2-antagonst), or rauwolscine (alpha2B-, alpha2C-antagonist). None of these antagonists, however, affected baseline ICP. These results suggest that noradrenergic innervation of the HF that originates from the LC may play an active role in negative feedback regulation of penile erection, engaging at least alpha1A/D-, alpha2B-, and alpha2C-adrenoceptors in the HF.

Differential gene expression in a DNA double-strand-break repair mutant XRS-5 defective in Ku80: analysis by cDNA microarray

The ability of cells to rejoin DNA double-strand breaks (DSBs) usually correlates with their radiosensitivity. This correlation has been demonstrated in radiosensitive cells, including the Chinese hamster ovary mutant XRS-5. XRS-5 is defective in a DNA end-binding protein, Ku80, which is a component of a DNA-dependent protein kinase complex used for joining strand breaks. However, Ku80-deficient cells are known to be retarded in cell proliferation and growth as well as other yet to be identified defects. Using custom-made 600-gene cDNA microarray filters, we found differential gene expressions between the wild-type and XRS-5 cells. Defective Ku80 apparently affects the expression of several repair genes, including topoisomerase-I and -IIA, ERCC5, MLH1, and ATM. In contrast, other DNA repair-associated genes, such as GADD45A, EGR1 MDM2 and p53, were not affected. In addition, for large numbers of growth-associated genes, such as cyclins and clks, the growth factors and cytokines were also affected. Down-regulated expression was also found in several categories of seemingly unrelated genes, including apoptosis, angiogenesis, kinase and signaling, phosphatase, stress protein, proto-oncogenes and tumor suppressors, transcription and translation factors. A RT-PCR analysis confirmed that the XRS-5 cells used were defective in Ku80 expression. The diversified groups of genes being affected could mean that Ku80, a multi-functional DNA-binding protein, not only affects DNA repair, but is also involved in transcription regulation. Our data, taken together, indicate that there are specific genes being modulated in Ku80- deficient cells, and that some of the DNA repair pathways and other biological functions are apparently linked, suggesting that a defect in one gene could have global effects on many other processes.

Correlation between Abetax-40-, Abetax-42-, and Abetax-43-containing amyloid plaques and cognitive decline

CONTEXT

Accumulation of senile plaques containing amyloid beta (Abeta)-protein is a pathologic hallmark of Alzheimer disease. Amyloid beta-peptide is heterogeneous, with carboxyterminal variants ending at residues Val40 (Abetax-40), Ala42 (Abetax-42), or Thr43 (Abetax-43). The relative importance of each of these variants in dementia or cognitive decline remains unclear.

OBJECTIVE

To study whether Abeta deposition correlates with dementia and occurs at the earliest signs of cognitive decline.

DESIGN, SETTING, AND PATIENTS

Postmortem cross-sectional study comparing the deposition of Abeta variants in the prefrontal cortex of 79 nursing home residents having no, questionable, mild, moderate, or severe dementia.

MAIN OUTCOME MEASURES

Levels of staining of Abeta-peptides ending at amino acid 40, 42, or 43 in the frontal cortex, as a function of Clinical Dementia Rating score.

RESULTS

There were significant deposits of all 3 Abeta species that strongly correlated with cognitive decline. Furthermore, deposition of Abetax-42 and Abetax-43 occurred very early in the disease process before there could be a diagnosis of Alzheimer disease. Levels of deposited Abetax-43 appeared surprisingly high given the low amounts synthesized.

CONCLUSIONS

These data indicate that Abetax-42 and Abetax-43 are important species associated with early disease progression and suggest that the physiochemical properties of the Abeta species may be a major determinant in amyloid deposition. The results support an important role for Abeta in mediating initial pathogenic events in Alzheimer disease dementia and reinforce that treatment strategies targeting the formation, accumulation, or cytotoxic effects of Abeta should be pursued.

Expression of human BRE in multiple isoforms

BRE, a putative stress-modulating gene, found able to down-regulate TNF-alpha-induced NF-kappaB activation upon overexpression, is now shown in human cells expressed as multiple mRNA isoforms. A total of six isoforms are produced by alternative splicing predominantly at either end of the gene. Predicted from the cDNA sequences of these isoforms, three of them (alpha(a), alpha(b), and alpha(c)) code for BRE of different C-terminus, and the other three (beta(a), beta(b), and beta(c)) may possibly be the nonfunctional counterparts. All human cells examined coexpress all the predominant splice variants, albeit at different ratios. Comparing with normal cells, immortalized human cell lines uniformly express higher levels of BRE. Interestingly, peripheral blood monocytes responded to LPS by down-regulating the expression of all the BRE isoforms, which was however less obvious in the cell line counterpart, THP-1. Isoform alpha(a), which codes for the canonical BRE with a C-terminal peroxisomal targeting sequence, is the most abundant transcript. We propose that the function of BRE and its isoforms is to regulate peroxisomal activities.

Engagement of inducible nitric oxide synthase at the rostral ventrolateral medulla during mevinphos intoxication in the rat

We evaluated the relationship between the toxicity induced by the organophosphate mevinphos (Mev) and inducible nitric oxide synthase (iNOS) in the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic neurogenic vasomotor tone. Adult Sprague-Dawley rats that were anesthetized and maintained with propofol were used. Laser scanning confocal microscopic analysis revealed colocalization of the M2 subtype of muscarinic receptors (M(2)R) and iNOS immunoreactivity in RVLM neurons. Comicroinjection bilaterally of Mev (10 nmol) and artificial cerebrospinal fluid (aCSF) into the RVLM elicited a progressive decline in systemic arterial pressure (SAP) and heart rate. This was accompanied during phase 1 Mev intoxication by an increase in the power density of the very high-frequency (VHF; 5-9 Hz), high-frequency (HF; 0.8-2.4 Hz), low-frequency (LF; 0.25- 0.8 Hz) and very low-frequency (VLF; 0-0.25 Hz) components of SAP signals. Phase 2 exhibited a reversal of the VHF and VLF power to control levels and a further reduction in the power density of both HF and LF components to below baseline. Hypotension and bradycardia promoted by Mev were significantly blunted on coadministration into the RVLM of the selective iNOS inhibitors S-methylisothiourea (250 pmol) or aminoguanidine (250 pmol). Not only was the augmented power density of HF and LF components during phase 1 Mev intoxication further enhanced, the reduced power of these two spectral components during phase 2 was appreciably antagonized. On the other hand, the temporal changes in VHF and VLF power were essentially the same as with coadministration of Mev and aCSF. We conclude that, as a cholinesterase inhibitor, Mev may induce toxicity via nitric oxide produced by iNOS on activation of the M(2)R by the accumulated acetylcholine in the RVLM.

Reduced functional expression and molecular synthesis of inducible nitric oxide synthase in rostral ventrolateral medulla of spontaneously hypertensive rats

BACKGROUND

We demonstrated recently that the prevalence of neuronal (nNOS) over inducible (iNOS) nitric oxide synthase activity at the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic neurogenic vasomotor tone, and the associated dominance of sympathoexcitation over sympathoinhibition underlie the maintenance of sympathetic vasomotor outflow by the endogenous NO. Here, we evaluated the hypothesis that a significant downregulation of iNOS at the RVLM may play a crucial role in the genesis of augmented sympathetic vasomotor tone during hypertension.

METHODS AND RESULTS

Spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats anesthetized with propofol were used. Compared with SHR, the hypotension, bradycardia, or depression in sympathetic vasomotor tone induced by bilateral microinjection of lipopolysaccharide (5 or 10 ng) into the RVLM of WKY rats exhibited significantly shorter-onset latency, appreciably steeper slope, and a greater incidence of mortality. All these effects of lipopolysaccharide (10 ng) were significantly blunted by coadministration of the selective iNOS inhibitor S-methylisothiourea (250 pmol). Reverse transcription-polymerase chain reaction and Western blot analyses further revealed significantly lower iNOS mRNA and protein levels at the ventrolateral medulla in SHR under basal conditions or on activation by lipopolysaccharide (10 ng). Conversely, nNOS mRNA and protein levels remained constant in the RVLM and were comparable in both strains of rats.

CONCLUSIONS

We conclude that a significant downregulation in both functional expression and molecular synthesis of iNOS at the RVLM may underlie the augmented sympathetic vasomotor tone during hypertension.

GABAergic neurotransmission at the nucleus tractus solitarii in the suppression of reflex bradycardia by parabrachial nucleus

We investigated the role of GABAergic neurotransmission at the nucleus tractus solitarii (NTS) in the suppression of cardiac baroreceptor reflex (BRR) response induced by parabrachial nucleus (PBN) complex in adult Sprague-Dawley rats maintained under pentobarbital anesthesia. Based on in vivo microdialysis coupled with high-performance liquid chromatography-fluorescence detection for gamma-aminobutyric acid (GABA), we found that electrical stimulation of the ventrolateral regions and Koelliker-Fuse (KF) subnucleus of PBN complex resulted in a site-specific increase in GABA concentration in the dialysate collected from the NTS. The temporal increase in extracellular GABA concentration in the NTS coincided with the time course of PBN-induced cardiac BRR inhibition. In addition, the PBN-induced cardiac BRR suppression was reversed by microinjection bilaterally into the NTS of a GABA(A) receptor antagonist, bicuculline methiodide (5 pmol), or a GABA(B) receptor antagonist, 2-OH saclofen (500 pmol). Blockade of neuronal activity in the ventrolateral regions and KF subnucleus of PBN complex with lidocaine (5%) elicited an enhancement of the same reflex response. The time course of this facilitatory effect of lidocaine correlated positively with the temporal decrease in extracellular GABA concentration in the NTS. Anatomically, Fast Blue-labeled neurons were identified in the same subnuclei of the PBN complex after microinjection of the retrograde transport tracer into the NTS. Some of these Fast Blue-labeled neurons were also immunoreactive to glutamic acid decarboxylase. These results suggest that a direct GABAergic descending projection from the KF subnucleus and surrounding areas of the PBN complex to the NTS may inhibit cardiac BRR response by activating GABA(A) and GABA(B) receptors at the NTS.

Fibroblast growth factor-8b-stimulated myogenic cell proliferation is suppressed by the promyelocytic leukemia gene

Muscle cell growth is regulated by growth-promoting and -inhibiting factors. In this study, the physiological effects of fibroblast growth factor (FGF)-8b and the promyelocytic leukemia (PML) gene on G8 myogenic cells were examined. FGF-8b was found to strongly stimulate myogenic cell proliferation. Signal transduction assays using AP-1/SEAP and E-box/SEAP reporters revealed that the transcriptional factors junB/c-fos and c-myc were involved in FGF-8b-stimulated G8 cell growth. Besides examining factors that positively stimulate myogenic cell growth, we also examined genes that negatively affect cell growth. PML is a growth suppressor gene and we studied its expression in G8 cells under different growth conditions. Immunohistochemical staining revealed that in the presence of low serum, PML was expressed in approximately 23.2% of all cultured G8 cells. However, under normal culture conditions (10% serum), PML expression dropped to about 2.6%. We found that the PML gene acted antagonistically to FGF-8b, as the overexpression of PML in G8 cells significantly inhibited FGF-8b-stimulated cell proliferation. It also inhibited AP-1 and E-box transactivation. However, we believe that PML functions as a stress-response gene in G8 cells rather than as a gene normally involved in regulating muscle development.

Modulation of catecholamine release by endogenous adenosine in the rat adrenal medulla

Adenosine was shown to inhibit norepinephrine (NE) release from sympathetic nerve endings. The purpose of this study was to examine whether endogenous adenosine restrains NE and epinephrine release from the adrenal medulla. The effects of an adenosine receptor antagonist, 1,3-dipropyl-8-(p-sulfophenyl) xanthine (DPSPX), on epinephrine and NE release induced by intravenous administration of insulin in conscious rats were examined. Plasma catecholamines were measured by HPLC with an electrochemical detector. DPSPX significantly increased plasma catecholamine in both control rats and rats treated with insulin. The effect of DPSPX on plasma catecholamine was significantly greater in rats treated with insulin. Additional experiments were performed in adrenalectomized rats to investigate the contribution of the adrenal medulla to the effect of DPSPX on plasma catecholamine. The effect of DPSPX and insulin on epinephrine in adrenalectomized rats was significantly reduced compared with that of the controls. Finally, we tested whether endogenous adenosine restrains catecholamine secretion partially through inhibiting the renin-angiotensin system. The effect of DPSPX on plasma catecholamine in rats pretreated with captopril (an angiotensin-converting enzyme inhibitor) was reduced. These results demonstrate that under basal physiological conditions, endogenous adenosine tonically inhibits catecholamine secretion from the adrenal medulla, and this effect is augmented when the sympathetic system is stimulated. The effect of endogenous adenosine on catecholamine secretion from the adrenal medulla is achieved partially through the inhibitory effect of adenosine on the renin-angiotensin system.

Fos protein is required for the re-expression of angiotensin II type 1 receptors in the nucleus tractus solitarii after baroreceptor activation in the rat

We evaluated in Sprague--Dawley rats the hypothesis that Fos protein induced by baroreceptor activation in the nucleus tractus solitarii participates in transcriptional regulation of the expression of angiotensin receptor genes. Reverse transcription-polymerase chain reaction revealed that baroreceptor activation elicited by sustained hypertension resulted in a transient decrease in angiotensin II subtype 1, but not subtype 2, receptor messenger RNA, in the dorsomedial medulla, including the nucleus tractus solitarii. There was subsequently a transitory reduction in the pressor response elicited by microinjection bilaterally of angiotensin II (40 pmol) into the nucleus tractus solitarii, followed by an increase in c-fos messenger RNA and Fos immunoreactivity at the same nucleus. Both the re-expression of angiotensin II subtype 1 receptor messenger RNA and restoration of pressor response to angiotensin II after baroreceptor activation were significantly blunted by bilateral application into the nucleus tractus solitarii of an antisense oligonucleotide (50 pmol) that targets against the initiation codon of c-fos messenger RNA. Control pretreatment with the corresponding sense oligonucleotide (50 pmol), or an antisense c-fos oligonucleotide that targets against a different portion of the coding sequence of the c-fos messenger RNA (50 pmol), was ineffective. At the receptor level, the angiotensin II-induced pressor response was antagonized by the subtype 1 receptor antagonist losartan (1.6 nmol), but not by the subtype 2 receptor antagonist PD-123319 (1.6 nmol). These findings suggest that sustained hypertension down-regulates angiotensin II subtype 1 receptors at both messenger RNA and functional expression levels in the nucleus tractus solitarii. Furthermore, Fos protein induced in the nucleus tractus solitarii by baroreceptor activation may play a permissive role in the transcriptional regulation of the re-expression of this subtype of angiotensin receptors.

Potentiation of baroreceptor reflex response by heat shock protein 70 in nucleus tractus solitarii confers cardiovascular protection during heatstroke

BACKGROUND

Whereas hypotension and bradycardia seen during the onset of heatstroke may be protected by prior induction of heat shock protein 70 (HSP70) in the brain, the underlying mechanism is not fully understood. We evaluated the hypothesis that HSP70 may confer cardiovascular protection during heatstroke by potentiating the baroreceptor reflex (BRR) control of peripheral hemodynamic performance.

METHODS AND RESULTS

Adult male Sprague-Dawley rats subjected to a brief hyperthermic heat shock (HS; 42 degrees C for 15 minutes) induced discernible expression of HSP70 in the bilateral nucleus tractus solitarii (NTS), the terminal site in the brain stem for primary baroreceptor afferents. This HSP70 expression was detected at 8 hours, peaked at 24 hours, and returned to baseline by 48 hours after HS. Brief hyperthermia also significantly potentiated the BRR response in a temporal profile that correlated positively with changes in HSP70 expression at the NTS. Prior HS also appreciably alleviated hyperthermia, severe hypotension, and bradycardia manifested during the onset of heatstroke (45 degrees C for 60 minutes) elicited 24 hours later. Microinjection bilaterally of anti-HSP70 antiserum (1:20) into the NTS or denervation of the sinoaortic baroreceptor afferents significantly reversed the enhancement of BRR response and cardiovascular protection during heatstroke induced by prior HS.

CONCLUSIONS

These results suggest that HS-induced expression of HSP70 in the NTS may alleviate severe hypotension and bradycardia exhibited during the onset of heatstroke by potentiating both the sensitivity and capacity of BRR response.

Reduced oxidative-stress response in red blood cells from p45NFE2-deficient mice

p45NF-E2 is a member of the cap 'n' collar (CNC)-basic leucine zipper family of transcriptional activators that is expressed at high levels in various types of blood cells. Mice deficient in p45NF-E2 that were generated by gene targeting have high mortality from bleeding resulting from severe thrombocytopenia. Surviving p45nf-e2(-/-) adults have mild anemia characterized by hypochromic red blood cells (RBCs), reticulocytosis, and splenomegaly. Erythroid abnormalities in p45nf-e2(-/-) animals were previously attributed to stress erythropoiesis caused by chronic bleeding and, possibly, ineffective erythropoiesis. Previous studies suggested that CNC factors might play essential roles in regulating expression of genes that protect cells against oxidative stress. In this study, we found that p45NF-E2-deficient RBCs have increased levels of reactive oxygen species and an increased susceptibility to oxidative-stress-induced damage. Deformability of p45NF-E2-deficient RBCs was markedly reduced with oxidative stress, and mutant cells had a reduced life span. One possible reason for increased sensitivity to oxidative stress is that catalase levels were reduced in mutant RBCs. These findings suggest a role for p45NF-E2 in the oxidative-stress response in RBCs and indicate that p45NF-E2 deficiency contributes to the anemia in p45nf-e2(-/-) mice. (Blood. 2001;97:2151-2158)

Tonic suppression of spontaneous baroreceptor reflex by endogenous angiotensins via AT(2) subtype receptors at nucleus reticularis ventrolateralis in the rat

We evaluated the role of endogenous angiotensins at the rostral nucleus reticularis ventrolateralis (NRVL) in the modulation of spontaneous baroreceptor reflex (BRR) response and the subtype of angiotensin receptors involved using rats anesthetized and maintained with pentobarbital sodium. Bilateral microinjection of angiotensin II (ANG II) or its active metabolite angiotensin III (ANG III) (5, 10, or 20 pmol) into the NRVL significantly suppressed the spontaneous BRR response, as represented by the magnitude of transfer function between systemic arterial pressure and heart rate signals. The inhibitory effect of ANG III (20 pmol) was discernibly reversed by coadministration with its peptide antagonist, [Ile(7)]ANG III (1.6 nmol), or the nonpeptide AT(2) receptor antagonist, PD-123319 (1.6 nmol), but not by the nonpeptide AT(1) receptor antagonist, losartan (1.6 nmol). On the other hand, the peptide antagonist, [Sar(1), Ile(8)]ANG II (1.6 nmol) or both non-peptide antagonists appreciably reversed the suppressive action of ANG II (20 pmol). Whereas losartan produced minimal effect, blocking the endogenous activity of the angiotensins by microinjection into the bilateral NRVL of PD-123319, [Sar(1), Ile(8)]ANG II or [Ile(7)]ANG III elicited significant enhancement of the spontaneous BRR response. We conclude that under physiologic conditions both endogenous ANG II and ANG III may exert a tonic inhibitory modulation on the spontaneous BRR response by acting selectively on the AT(2) subtype receptors at the NRVL.

Differential expression of a stress-modulating gene, BRE, in the adrenal gland, in adrenal neoplasia, and in abnormal adrenal tissues

Genes that modulate the action of hormones and cytokines play a critical role in stress response, survival, and in growth and differentiation of cells. Many of these biological response modifiers are responsible for various pathological conditions, including inflammation, infection, cachexia, aging, genetic disorders, and cancer. We have previously identified a new gene, BRE, that is responsive to DNA damage and retinoic acid. Using multiple-tissue dot-blotting and Northern blotting, BRE was recently found to be strongly expressed in adrenal cortex and medulla, in testis, and in pancreas, whereas low expression was found in the thyroid, thymus, small intestine and stomach. In situ hybridization and immunohistochemical staining indicated that BRE was strongly expressed in the zona glomerulosa of the adrenal cortex, which synthesizes and secretes the mineralocorticoid hormones. It is also highly expressed in the glial and neuronal cells of the brain and in the round spermatids, Sertoli cells, and Leydig cells of the testis, all of which are associated with steroid hormones and/or TNF synthesis. However, BRE expression was downregulated in human adrenal adenoma and pheochromocytoma, whereas its expression was enhanced in abnormal adrenal tissues of rats chronically treated with nitrate or nitrite. These data, taken together, indicate that the expression of BRE is apparently associated with steroids and/or TNF production and the regulation of endocrine functions. BRE may play an important role in the endocrine and immune system, such as the cytokine-endocrine interaction of the adrenal gland.

Effects of stress during pregnancy on maternal behavior in mice

The effects of stress experienced during pregnancy and raising stressed offspring on maternal behavior were investigated in Swiss-Webster mice. Dams were either stressed or not stressed during pregnancy, and raised either prenatally stressed or nonstressed cross-fostered pups. Maternal behaviors such as grooming, nursing, pup retrieval and maternal aggression were assessed during the first 4 days after birth. Nonstressed dams raising stressed pups and stressed dams raising nonstressed pups groomed and nursed their pups significantly less than did control dams (stressed dams raising stressed pups and nonstressed dams raising nonstressed pups). Nonstressed dams raising stressed pups were also the slowest to retrieve both the first and last pup in retrieval tests. Nonstressed dams raising nonstressed pups were significantly less aggressive than other dams. In contrast, stressed dams raising stressed pups exhibited high levels of nursing and grooming, retrieved their pups rapidly and were very aggressive towards an intruder. These results indicate that raising stressed pups, or experiencing stress during a pregnancy can have significant effects on maternal behaviors. Stressed dams raising stressed pups exhibit maternal care comparable to that of nonstressed dams raising nonstressed pups at least for nesting/nurturing behaviors, and show increased levels of aggression and pup retrieval.

Relationship between novel isoforms, functionally important domains, and subcellular distribution of CD164/endolyn

Functional analyses have indicated that the human CD164 sialomucin may play a key role in hematopoiesis by facilitating the adhesion of human CD34(+) cells to the stroma and by negatively regulating CD34(+)CD38(lo/-) cell proliferation. We have identified three novel human CD164 variants derived by alternative splicing of bona fide exons from a single genomic transcription unit. The predominant CD164(E1-6) isoform, encoded by six exons, is a type I transmembrane protein containing two extracellular mucin domains (I and II) interrupted by a cysteine-rich non-mucin domain. The 103B2/9E10 and 105A5 epitopes, which specify ligand binding characteristics, are located on the exon 1-encoded mucin domain I. Three human CD164(E1-6) mRNA species, exhibiting differential polyadenylation site usage, are differentially expressed in hematopoietic and non-hematopoietic tissues. This study provides additional evidence that human CD164(E1-6) represents the ortholog of murine MGC-24v and rat endolyn. Comparative analysis of murine MGC-24v/CD164(E1-6) with human CD164(E1-6) revealed two potential splice variants and a similar genomic structure. Whereas the human CD164 gene is located on chromosome 6q21, the mouse gene occurs in a syntenic region on chromosome 10B1-B2. By confocal microscopy, human CD164 in CD34(+)CD38(+) hematopoietic progenitor (KG1B) and epithelial cell lines appears to be localized primarily in endosomes and lysosomes, with low concentrations at the cell surface. However, in a minority of KG1B cells, CD164 is more prominently expressed at the plasma membrane and in the recycling endosomes, suggesting that its distribution is regulated in cells of hematopoietic origin.

Rostral ventrolateral medulla suppresses reflex bradycardia by the release of gamma-aminobutyric acid in nucleus tractus solitarii of the rat

We investigated the role of gamma-aminobutyric acid (GABA) in the nucleus tractus solitarii (NTS), the principal recipient of baroreceptor afferent fibers in the medulla oblongata, in the suppression of cardiac baroreceptor reflex (BRR) response by the rostral ventrolateral medulla (RVLM). Direct microinfusion via reverse microdialysis of L-glutamate (50 microM) into the RVLM promoted an inhibition of the BRR response, alongside an increase in the concentration of GABA in the dialysate collected from the ipsilateral NTS. Such an increase in GABA concentration in the NTS to RVLM activation was site-specific, as microinfusion of L-glutamate into areas outside the confines of RVLM resulted in no discernible change in GABA concentration in the dialysate of the NTS and minimal effect on the cardiac BRR response. The RVLM-induced BRR suppression of cardiac BRR response to microinjection into the bilateral RVLM of L-glutamate (1 nmol) was antagonized by administration into the bilateral NTS of the GABA(A) receptor antagonist, bicuculline methiodide (1 or 5 pmol), or the GABA(B) receptor antagonist, 2-hydroxy-saclofen (100 or 500 pmol). These results suggest that GABA released in the NTS may participate in cardiac BRR suppression induced by glutamatergic activation of the RVLM, via an action on both GABA(A) and GABA(B) receptor subtypes.

Differential roles of iNOS and nNOS at rostral ventrolateral medulla during experimental endotoxemia in the rat

We investigated the differential contribution of inducible and neuronal nitric oxide synthase (iNOS and nNOS) at the rostral ventrolateral medulla (RVLM) to endotoxemia induced by E. coli lipopolysaccharide (LPS). In Sprague-Dawley rats maintained under propofol anesthesia, i.v. administration of LPS (15, 30, or 45 mg/kg) induced a reduction (phase I), followed by an augmentation (phase II) and a secondary decrease (phase III) in the power density of the vasomotor components (0-0.8 Hz) in systemic arterial pressure (SAP) signals. LPS also induced an immediate hypotension, followed by a rebound increase and a secondary decrease in SAP. In addition, the level of iNOS mRNA exhibited a significant surge that began with phase I endotoxemia, reaching progressively its peak at phase III. Discernible down-regulation of nNOS mRNA was not detected until the last phase of endotoxemia. Pretreatment with microinjection of the selective iNOS inhibitor, aminoguanidine (250 pmol), into the bilateral RVLM significantly prolonged phases II and III endotoxemia, blunted the initial and secondary hypotension, and antagonized the upregulation of iNOS mRNA. Similar pretreatment with the selective nNOS inhibitor, 7-nitroindazole (1 pmol), on the other hand, discernibly shortened phase II and prolonged phase III endotoxemia, and induced progressive hypotension by antagonizing the rebound increase in SAP. We conclude that the relative prevalence of functional expression and molecular synthesis of iNOS over nNOS in the RVLM may be a crucial determinant for the reduction or loss in power density of the vasomotor components of SAP signals during experimental endotoxemia.

Impaired expression of glutathione synthetic enzyme genes in mice with targeted deletion of the Nrf2 basic-leucine zipper protein

Transcriptional activation of genes that play a role in detoxification of xenobiotics and defense against oxidative stress is mediated in part by the antioxidant response element (ARE). For example, it has been shown that the promoters for both the heavy and light chain gamma-glutamylcysteine synthetase (GCS(H) and GCS(L)) genes require the ARE. CNC-bZIP factors, together with small Maf proteins, have been shown to bind as heterodimers to the NF-E2/AP-1 element, which is similar to the consensus sequence for the ARE. Nrf1 and Nrf2, two widely expressed CNC-bZIP factors, have been implicated in the regulation of genes involved in oxidative stress response. In this study, we examined the effect of nrf2 mutation on the expression of genes involved in glutathione synthesis. We observed that transcripts for gcs(H) and gcs(L) genes were decreased in nrf2(-/-) fibroblasts and livers. Correspondingly, glutathione levels were decreased in Nrf2 deficient livers and fibroblasts. By transient transfection studies in nrf2(-/-) fibroblasts, we show that transcriptional activation of reporter constructs bearing the human GCS(L) promoter, as well as the functional ARE of GCS(H) promoter, required the activator protein Nrf2. By electrophoretic mobility shift assay, recombinant Nrf2 binds the ARE of the GCS(L) and GCS(H) promoters. Overexpression of Nrf2 cDNA restored glutathione (GSH) levels in nrf2(-/-) fibroblasts, which correlated with increased steady state levels of gcs(H) and gcs(L) transcripts. These results establish a link between Nrf2 transcription factor and GSH biosynthesis.

Molecular cloning and expression analysis of human glycogen synthase kinase-3 alpha promoter

Human glycogen synthase kinase-3 alpha (GSK-3 alpha) is a serine/threonine kinase that phosphorylates a variety of cytoplasmic and nuclear proteins. It also phosphorylates components of the neuronal cytoskeleton including tau and neurofilament heavy chain. Hyperphosphorylated tau is found in neurofibrillary tangles, a hallmark of Alzheimer's disease and aberrant phosphorylation of neurofilament heavy chain is observed in motor neuron disease. Alterations in GSK-3 alpha activity may therefore contribute to the disease process in these disorders. As a first step to understand the transcriptional regulation of GSK-3 alpha, a 2-kb (p-1751/+243) DNA fragment upstream of the GSK-3 alpha initiation codon was obtained from a YAC clone and characterised. Using primer extension assays, a putative transcriptional start site was located to a G nucleotide 244 bp upstream of the ATG codon. Several transcription factor-binding sites were identified on the promoter region, but no TATA-like element was located close to the start site. Deletion mutants of the 2-kb DNA fragment were generated and fused to a promoterless chloramphenicol acetyltransferase (CAT) gene. Transfection study in a neuroblastoma cell line revealed the 1-kb (p-719/+243) fragment carried strong promoter activity, while the 2-kb construct that contains an Alu-like sequence was only 50% active.

Genomic structure, expression pattern, and chromosomal localization of the human calsenilin gene: no association between an exonic polymorphism and Alzheimer's disease

Calsenilin is a recently-identified member of the neuronal calcium sensor family. Like other members of this family, it is found in the brain and binds calcium. Calsenilin was discovered by virtue of its interaction with both presenilin-1 and -2, proteins that are involved in the etiology of Alzheimer's disease. Because calsenilin may play a role in Alzheimer's disease and other disease with alterations in calcium homeostasis, we characterized the human gene. The gene, which we localized to chromosome 2, extends over a region of at least 74 kb and includes nine exons. Interestingly, the ninth exon of calsenilin contains a highly polymorphic CA repeat, adjacent to the stop codon. In a study of Alzheimer patients and their unaffected siblings, there was no evidence of association of AD with any calsenilin allele. This CA repeat will be useful for linkage and linkage disequilibrium studies to determine whether calsenilin variants contribute to risk in other diseases.

Inhibition of P-glycoprotein expression and reversal of drug resistance of human hepatoma HepG2 cells by multidrug resistance gene (mdr1) antisense RNA

The development of multiple drug resistance in tumor cells is a significant problem in cancer therapy. In human, one of the reasons causing the resistance is due to the overexpression of the mdr1 gene product, P-glycoprotein. In our study, we had developed multiple drug resistant HepG2 cell line (HepG2/DR). To reverse the resistance, HepG2-DR cells were treated with antisense RNA against mdr1 gene. Total RNA and protein were extracted from the transfected cells. Northern analysis showed that mRNA level of mdr1 was decreased whereas a reduction in P-glycoprotein was detected by Western blot. By using flow cytometry, the ability of intracellular doxorubicin retention increased and drug efflux decreased in the treated cells. The result also showed that the cellular sensitivity to doxorubicin, vincristine and methotrexate measured in IC50 increased 83.3% 84.6% and 50% respectively. All these findings suggested that the expression of p-glycoprotein was successfully inhibited by antisense RNA and the drug resistance was reduced.

Parabrachial nucleus induces suppression of baroreflex bradycardia by the release of glutamate in the rostral ventrolateral medulla of the rat

The involvement of glutamatergic neurotransmission in the rostral ventrolateral medulla (RVLM) in the suppression of baroreflex bradycardia by the parabrachial nucleus (PBN) was investigated. Repeated electrical activation of the PBN increased the concentration of glutamate in the dialysate collected from the RVLM. The same stimulation also suppressed baroreflex bradycardia in response to transient hypertension evoked by phenylephrine (5 microg/kg, intravenously). Microinfusion of L-glutamate (10, 50 or 100 microM) via the microdialysis probe into the RVLM dose-dependently elicited a significant inhibition of baroreflex bradycardia that paralleled the concentration and time course of the PBN-elicited elevation in extracellular glutamate in the RVLM. The suppression of baroreflex bradycardia elicited by microinjection of L-glutamate (1 nmol) into the RVLM was appreciably reversed by coinjection of the NMDA receptor antagonist, dizocilpine (500 pmol), or the non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2, 3-dione (50 pmol). These results suggest that an increase in the extracellular concentration of glutamate and activation of both NMDA and non-NMDA receptors in the RVLM may mediate the suppression of baroreflex bradycardia by activation of the PBN.

Hippocampal noradrenergic neurotransmission in concurrent EEG desynchronization and inhibition of penile erection induced by cocaine in the rat

We previously reported that cocaine may induce activation of cortical (cEEG) and hippocampal (hEEG) electroencephalographic signals, concurrent with inhibition of penile erection, via an action on the hippocampal formation. The present study further evaluates the role of noradrenergic neurotransmission at the hippocampal formation in this process, using adult, male Sprague-Dawley rats anaesthetized and maintained by chloral hydrate. Unilateral microinjection of cocaine (100 nmoles) into the hippocampal CA1 or CA3 subfield or dentate gyrus elicited significant activation of both cEEG and hEEG activity. At the same time, the intracavernous pressure (ICP), our experimental index for penile erection, underwent a discernible reduction. Co-administration of equimolar doses (250 pmoles) of prazosin, naftopidil, yohimbine or rauwolscine significantly reversed those effects elicited by cocaine on cEEG, hEEG and ICP. Microinjection unilaterally of equimolar doses (5 nmoles) of norepinephrine, phenylephrine or BHT 933 into the hippocampal formation, similar to cocaine, also induced appreciable cEEG and hEEG excitation, with a simultaneous decrease in ICP. We conclude that cocaine may activate cEEG and hEEG and decrease ICP via noradrenergic neurotransmission, possibly engaging at least alpha(1A/D)-, alpha(2B)- and alpha(2C)-adrenoceptors at the hippocampal formation.

Functionally defined CD164 epitopes are expressed on CD34(+) cells throughout ontogeny but display distinct distribution patterns in adult hematopoietic and nonhematopoietic tissues

Three distinct classes of epitopes on human CD164 have been identified. Two of these, recognized by the monoclonal antibodies 105A5 and 103B2/9E10, are the CD164 class I and class II functionally defined epitopes, which cooperate to regulate adhesion and proliferation of CD34(+) cell subsets. In this article, we demonstrate that these 2 CD164 epitopes are expressed on CD34(+) cells throughout ontogeny, in particular on CD34(+ )cell clusters associated with the ventral floor of the dorsal aorta in the developing embryo and on CD34(+) hematopoietic precursor cells in fetal liver, cord blood, and adult bone marrow. While higher levels of expression of these CD164 epitopes occur on the more primitive AC133(hi)CD34(hi)CD38(lo/-) cell population, they also occur on most cord blood Lin(-)CD34(lo/-)CD38(lo/- )cells, which are potential precursors for the AC133(hi)CD34(hi)CD38(lo/-) subset. In direct contrast to these common patterns of expression on hematopoietic precursor cells, notable differences in expression of the CD164 epitopes were observed in postnatal lymphoid and nonhematopoietic tissues, with the class I and class II CD164 epitopes generally exhibiting differential and often reciprocal cellular distribution patterns. This is particularly striking in the colon, where infiltrating lymphoid cells are CD164 class I-positive but class II-negative, while epithelia are weakly CD164 class II-positive. Similarly, in certain lymphoid tissues, high endothelial venules and basal and subcapsular epithelia are CD164 class II-positive, while lymphoid cells are CD164 class I-positive. It therefore seems highly likely that these CD164 class I and II epitopes will mediate reciprocal homing functions in these tissue types.

Frequent integration of precore/core mutants of hepatitis B virus in human hepatocellular carcinoma tissues

The development of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) frequently follows persistent HBV infection and may arise in individuals who are hepatitis B e antigen (HBeAg) negative, indicating the possible presence of precore/core mutants. It is unclear whether precore/core mutants are associated with tumour development or are selected for after chromosomal integration of the wild-type viral DNA. We studied the status and sequence variation of the precore/core region of HBV in 56 patients with HBV-associated HCC and in various corresponding non-tumour tissues by Southern blot analysis, polymerase chain reaction and direct sequencing. Southern blot showed that integrated HBV DNA existed in 43 of 56 HCC tissues. Sequence analysis revealed mutations in 65% of the HCC (26/40) and 45% (14/31) of the corresponding non-tumour tissues. The mutation at nucleotide (nt) 1896, known to prevent HBeAg synthesis, was detected in 40% (16/40) of the tumours and in 35.4% (11/31) of the non-tumour tissues. Other mutations were found at nt 1899 (eight of 40 in HCC; three of 31 in non-tumour tissues), nt 1898 (seven of 40 in HCC; two of 31 in non-tumour tissues), nt 1912 (seven of 40 in HCC; none of 31 in non-tumour tissues) and nt 1886 (three of 40 in HCC; none of 31 in non-tumour tissues). To determine whether this finding merely reflected the prevalence of such mutants in this geographical region, HBV DNA from the sera of patients (also in this region) with acute and chronic hepatitis were sequenced. The nt 1896 mutant was found in 5.6% (one of 18) of patients with acute hepatitis B and in 22.8% (nine of 35) of patients with chronic hepatitis B. However, the nt 1898 mutation was not found in any of these sera. The precore/core mutant was observed with increasing frequency from acute hepatitis to chronic hepatitis, non-tumour and HCC, and this difference in frequency was significant between HCC and acute hepatitis B groups (P < 0.01), suggesting that the precore/core mutant or hepatocytes harbouring this mutant may be under immune selection and that such mutations may facilitate integration and subsequent tumour development.

Lack of expression for the suppressor PML in human small cell lung carcinoma

The promyelocytic leukemia (PML) gene, which encodes a transformation and growth suppressor, was first identified at the chromosomal translocation break point t(15;17) in acute promyelocytic leukemia (PML). To determine if the PML gene might be involved in other neoplasias such as lung cancer, PML expression was analyzed by immunohistochemical staining and in situ hybridization. Considerable PML protein expression in the PML-oncogenic domain (POD) structure was found in adenocarcinomas (ADC) and squamous cell carcinomas (SCC) of the lung, but was almost completely absent in all the small cell lung carcinomas (SCLC) examined. In situ hybridization showed that both mRNA and DNA of PML were present in SCLC and in normal lung, suggesting that the decreased protein expression was due to either a defect in translation or protein instability, rather than the consequence of decreased transcription or gene deletion. Double staining showed that PML expression was inversely correlated with the proliferation marker Ki-67 and positively correlated with levels of apoptotic cells in these tumors. To determine if the precursor cells of SCLC, the neuroendocrine-producing cells, express PML, double labeling was performed with PML and chromogranin A, a bio-marker for neuroendocrine cells. Neuroendocrine cells from normal tissues were found to be PML positive, indicating that the lack of PML protein in SCLC is associated with the tumorigenic phenotype and is not the result of cell-lineage specificity. Thus, the decreased PML expression may play an important role in SCLC development.

CD164--a novel sialomucin on CD34+ cells

Hematopoiesis in adult bone marrow is a tightly regulated process involving interactions between cytokine and adhesion receptors on hematopoietic progenitor cells and their cognate ligands in the immediate microenvironment. These interactions control hematopoietic stem cell self-renewal, quiescence, commitment and migration. Recently, sialomucins have assumed some importance in hematopoiesis, with six of these receptors, CD34, PSGL-1, CD43, PCLP, CD45RA and CD164, having been identified on primitive hematopoietic precursor cells and/or their associated stromal/endothelial elements. This article reviews the cloning, expression and function of the recently identified sialomucin, CD164, which is highly expressed by primitive hematopoietic progenitor cells. The CD164 receptor is implicated in mediating or regulating hematopoietic precursor cell adhesion to stroma, and may serve as a potent negative regulator of hematopoietic progenitor cell proliferation.

Hepatitis B virus reactivation in patients undergoing cytotoxic chemotherapy for solid tumours: precore/core mutations may play an important role

Reactivation of the hepatitis B virus (HBV) is a rare, but well described complication of cytotoxic chemotherapy that may result in hepatic failure. Patients who are chronic carriers of the HBV and who have a G to A mutation at nucleotide 1896 in the precore region may develop more severe liver disease, possibly because of rapid selection and enhanced replication ability of the mutant strain. Such mutant viruses have been implicated occasionally in chemotherapy induced reactivation of hepatitis B virus. In this report, 5 patients with solid tumours were identified to have developed severe hepatitis B virus related liver disease during treatment with cytotoxic agents (with dexamethasone as anti-emetic). All had clinical and serological evidence of reactivation of the HBV. Three patients developed icteric hepatitis; 2 fully recovered, and 1 had died from progressive metastatic disease while recovering from the reactivation. The other two died from progressive liver failure. Direct sequencing of the polymerase chain reaction (PCR) products of the precore (preC) and precore promoter region of the HBV-DNA was carried out on the patients' serum samples taken during the episode of reactivation. In each case, similar mutations (G to A) in nucleotide 1896 of the preC region were found, together with additional mutations in the preC promoter. The present findings suggest that reactivation involving a mutant hepatitis B virus may lead to liver failure, which is possibly more severe than that caused by wild type HBV, and can be triggered by cytotoxic chemotherapy, or the administration of corticosteroids. In Eastern Asia the HBV carriage rate in adults is high. HBV reactivation and severe liver disease during cytotoxic treatment may become a serious and common problem in this region as cytotoxic chemotherapy is more widely used. Patients should be screened routinely for HBsAg in endemic areas of chronic hepatitis B virus infection prior to receiving cytotoxic treatment. The possibility of HBV reactivation should be considered in patients developing liver dysfunction. Patients who are HBeAg negative/Anti-HBe positive, and are suspected to be having an HBV reactivation, should have HBV-DNA levels measured for confirmation as they may carry a mutant HBV.

Bmp-4 requires the presence of the digits to initiate programmed cell death in limb interdigital tissues

The effects of Bmp-4 on interdigital cell death were investigated in the mouse. Affi-Gel beads, loaded with recombinant Bmp-4 protein, were transplanted into the interdigital tissues of day 12.5 hindlimb, ex utero. It was established that Bmp-4 could induce precocious interdigital cell death. Using in situ hybridization, the expression patterns of bmp-4 and alk-6 receptor were established. Both genes were found coexpressed in the interdigital region of 12.5- and 13. 5-day hindlimbs. This suggests that Bmp-4 may act in an autocrine fashion. We have also studied the effects of Bmp-4 on 12.5-day interdigital tissue cultures. In all specimens examined, the interdigital tissues produced cartilage instead of participating in cell death. The addition of exogenous Bmp-4 to the interdigital cultures did not induce apoptosis but instead enhanced chondrogenesis. The discrepancy between the effects of Bmp-4 in vitro and ex utero was attributed to the presence of digits. When a flanking digit was left attached to the interdigital tissues, in vitro, Bmp-4 promoted apoptosis instead of chondrogenesis. In sum, the results suggest that Bmp-4 is a multifunctional protein and its effect on the interdigital tissues is dependent on the modulating influence of the digits.

Role of calcium/calmodulin-dependent protein kinases in expression of Fos protein in the nucleus tractus solitarii after sustained hypertension

We investigated the role of calcium/calmodulin-dependent protein kinases in the phosphorylation of cyclic AMP response element binding protein and subsequent induction of c-fos gene elicited by sustained hypertension in neurons of the nucleus tractus solitarii of anesthetized rats. Activation of glutamate receptors in the nucleus tractus solitarii significantly increased the number of neurons that were immunoreactive to phosphorylated cyclic AMP response element binding protein and Fos protein. Microinjection bilaterally into the nucleus tractus solitarii of the calcium/calmodulin-dependent protein kinase inhibitor, 1-[N,O-bis(5-isoquinolinesulfonyl-N-methyl-L-tyrosyl]-4-phenylpiperazine , appreciably blunted such an increase. This inhibitor also attenuated the augmented immunoreactivity for phosphorylated cyclic AMP response element binding protein or Fos protein in the same nucleus induced by sustained hypertension. These results were comparable to those observed after blockade of either N-methyl-D-aspartate or non-N-methyl-D-aspartate ionotropic glutamate receptors in the nucleus tractus solitarii. Reverse transcription-polymerase chain reaction further indicated that the calcium/calmodulin-dependent protein kinase blocker attenuated the expression of Fos protein induced by sustained hypertension in the nucleus tractus solitarii by suppressing the transcription of c-fos messenger RNA. The present results suggest that activation of calcium/calmodulin-dependent protein kinases may represent an important step in the cascade of intracellular events that leads to phosphorylation of cyclic AMP response element binding protein and subsequent induction of c-fos gene after activation of ionotropic glutamate receptors by baroceptive signals in the nucleus tractus solitarii.

The CNC basic leucine zipper factor, Nrf1, is essential for cell survival in response to oxidative stress-inducing agents. Role for Nrf1 in gamma-gcs(l) and gss expression in mouse fibroblasts

Nrf1 is a member of the CNC-basic leucine zipper (CNC-bZIP) family of transcription factors. CNC bZIP factors, together with small Maf proteins, bind as heterodimers to the NF-E2/AP-1 element. Similarity between the NF-E2/AP-1 element and the antioxidant response element identified in a number of promoters of genes involved in detoxification and antioxidant response raises the possibility that Nrf1 plays a role in mediating the antioxidant response element response. In this study, we exploited the availability of cells from Nrf1 knockout mice to study the role of Nrf1 transcription factor in the regulation of antioxidant gene expression and in cellular antioxidant response. Fibroblast cells derived from Nrf1 null embryos showed lower levels of glutathione and enhanced sensitivity to the toxic effects of oxidant compounds. Our results indicate that Nrf1 plays a role in the regulation of genes involved in glutathione synthesis and suggest a basis for a correspondingly low GSH concentration and reduced stress response.

Involvement of apamin-sensitive SK channels in spike frequency adaptation of neurons in nucleus tractus solitarii of the rat

We delineated the role of Ca(2+)-activated K(+) channels in the phenomenon of spike frequency adaptation (SFA) exhibited by neurons in the caudal region of nucleus tractus solitarius (cNTS) using intracellular recording coupled with the current-clamp technique in rat brain slices. Intracellular injection of a constant depolarizing current evoked a train of action potentials whose discharge frequency declined rapidly to a lower steady-state level of irregular discharges. This manifested phenomenon of SFA was found to be related to extracellular Ca(2+). Low Ca(2+) (0.25 mM) or Cd(2+) (0.5 mM) in the perfusing medium resulted in a significant increase in the adaptation time constant (tau(adap)) and an appreciable reduction in the percentage adaptation of spike frequency (F(adap)). In addition, the evoked discharges were converted from an irregular to a regular pattern, accompanied by a profound increase in mean firing rate. Intriguingly, similar alterations in tau(adap), F(adap), discharge pattern and discharge rate were elicited by apamin (1 microM), a selective blocker for small-conductance Ca(2+)-activated K(+) (SK) channels. On the other hand, charybdotoxin (0.1 microM), a selective blocker for large-conductance Ca(2+)-activated K(+) channels, was ineffective. Our results suggest that SK channels of cNTS neurons may subserve the generation of both SFA and irregular discharge patterns displayed by action potentials evoked with a prolonged depolarizing current.