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1.
World J Clin Cases ; 11(16): 3891-3898, 2023 Jun 06.
Article in English | MEDLINE | ID: mdl-37383123

ABSTRACT

BACKGROUND: Neurodevelopmental-craniofacial syndrome with variable renal and cardiac abnormalities (NECRC) is a rare, autosomal, dominant neurological disorder caused by mutations in the ZMYM2 gene. To date, the clinical and functional characteristics of the novel ZMYM2 mutation c.2090_2091del have not yet been reported. CASE SUMMARY: The patient was an 18.5-mo-old Chinese boy with motor and language delay, microcephaly, facial dysmorphism, moderate malnutrition, single palmar crease on the left hand, synpolydactyly of the right foot, hypotonia and feeding problems. The boy who was diagnosed with NECRC was enrolled in the First Affiliated Hospital, Henan University of Chinese Medicine, and his clinical data were collected. From the whole-exon sequencing (WES) data, the pathogenic SNVs/InDels were identified, and the molecular findings were characterized. WES revealed that the heterozygous variant in the ZMYM2 gene was c.2090_2091del, p.Ser697TrpfsTer3, a frameshift mutation, which is a NECRC-related gene mutation. CONCLUSION: We performed a systematic literature review to identify and characterize NECRC. Substantial evidence from the literature indicated that patients with ZMYM2 gene mutation showed different degrees of intellectual disability, motor and language retardation, facial dysmorphism, and a few had congenital heart defects, kidney and urinary tract abnormalities. Early diagnosis and prompt management with comprehensive rehabilitation training are beneficial, but may not improve long-term outcomes.

2.
Neuroscience ; 415: 59-69, 2019 09 01.
Article in English | MEDLINE | ID: mdl-31301366

ABSTRACT

Exposure to commonly used anesthetics is associated with widespread neuroapoptosis in neonatal animals. Vulnerability of developing hippocampal dentate gyrus granule cells to anesthetic neurotoxicity peaks approximately 2 weeks after cell birth, as measured by bromodeoxyuridine birth dating, regardless of the age of the animal. The present study examined whether the vulnerable window can be further characterized by utilizing a transgenic approach. Proopiomelanocortin enhanced green fluorescent protein (POMC-EGFP) mice (postnatal day 21) were exposed to 3% sevoflurane for 6 h. Following exposure, cleaved caspase 3, expression of EGFP and differential maturational markers were quantified and compared with unanesthetized littermates. Electrophysiological properties of EGFP+ and EGFP- cells in the subgranular zone and the inner half of the granule cell layer were recorded by whole-cell patch-clamp. We found that sevoflurane significantly increased apoptosis of POMC-EGFP+ granule cells that accounted for approximate 1/3 of all apoptotic cells in dentate gyrus. Apoptotic EGFP- granule cells more frequently expressed the immature neuronal marker calretinin (75.4% vs 45.0%, P < 0.001) and less frequently the late progenitor marker NeuroD1 (21.9% vs 87.9%, P < 0.001) than EGFP+ granule cells. Although EGFP- granule cells were more mature in immunostaining than EGFP+ granule cells, their electrophysiological properties partially overlapped in terms of input resistance, resting membrane potential and action potential amplitude. Our results revealed the POMC stage, when GABA acts as an excitatory neurotransmitter, only partly captures susceptibility to anesthetic neurotoxicity, suggesting the vulnerable window of anesthesia-induced neuroapoptosis extends from the end of POMC+ stage to the post-POMC+ stage when depolarizing glutamatergic inputs emerge.


Subject(s)
Anesthesia/adverse effects , Dentate Gyrus/drug effects , Dentate Gyrus/metabolism , Green Fluorescent Proteins , Pro-Opiomelanocortin , Sevoflurane/adverse effects , Animals , Apoptosis , Cell Differentiation , Dentate Gyrus/physiology , Membrane Potentials , Mice , Mice, Inbred C57BL , Mice, Transgenic , Neurogenesis/drug effects , Neurons/drug effects , Neurons/metabolism
3.
Bioorg Chem ; 69: 129-131, 2016 12.
Article in English | MEDLINE | ID: mdl-27814566

ABSTRACT

Baicalin is one of the active ingredients in the skullcap, with a variety of pharmacological effects, such as blood pressure reduction, sedation, liver-protection, gallbladder-protection, anti-bacteria, and anti-inflammation. In our study, baicalin was first characterized as a LSD1 inhibitor with an IC50 of 3.01µM and showed strong LSD1 inhibitory effect in cells. Baicalin may serve as a template for designing flavone-based LSD1 inhibitors.


Subject(s)
Biological Products/pharmacology , Enzyme Inhibitors/pharmacology , Flavonoids/pharmacology , Histone Demethylases/antagonists & inhibitors , Biological Products/chemical synthesis , Biological Products/chemistry , Cell Line, Tumor , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Flavonoids/chemical synthesis , Flavonoids/chemistry , Histone Demethylases/metabolism , Humans , Molecular Conformation , Structure-Activity Relationship
4.
Mol Brain ; 9(1): 73, 2016 07 29.
Article in English | MEDLINE | ID: mdl-27472923

ABSTRACT

Itch and pain share similar mechanisms. It has been well documented that the anterior cingulate cortex (ACC) is important for pain-related perception. ACC has also been approved to be a potential pruritus-associated brain region. However, the mechanism of sensitization in pruriceptive neurons in the ACC is not clear. In current study, a chronic itch model was established by diphenylcyclopropenone (DCP) application. We found that both the frequency and amplitude of miniature excitatory postsynaptic currents in the ACC were enhanced after the formation of chronic itch. The paired-pulse ratio in ACC neurons recorded from the DCP group were smaller than those recorded in control group at the 50-ms interval. We also observe a significant increase in the AMPA/NMDA ratio in the DCP group. Moreover, an increased inward rectification of AMPARs in ACC pyramidal neurons was observed in the DCP group. Interestingly, the calculated ratio of silent synapses was significantly reduced in the DCP group compared with controls. Taken together, we conclude that a potentiation of synaptic transmission in the ACC can be induced by chronic itch, and unsilencing silent synapses, which probably involved recruitment of AMPARS, contributed to the potentiation of postsynaptic transmission.


Subject(s)
Gyrus Cinguli/physiopathology , Pruritus/pathology , Pruritus/physiopathology , Synaptic Transmission/physiology , Animals , Behavior, Animal , Chronic Disease , Cyclopropanes , Disease Models, Animal , Excitatory Postsynaptic Potentials/physiology , Gyrus Cinguli/pathology , N-Methylaspartate/metabolism , Neurons/pathology , Pruritus/chemically induced , Rats, Sprague-Dawley , Receptors, AMPA/metabolism , Up-Regulation , alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/metabolism
5.
Cell Physiol Biochem ; 38(1): 185-93, 2016.
Article in English | MEDLINE | ID: mdl-26784898

ABSTRACT

BACKGROUND/AIMS: Human SIRT1 is reported to be involved in tumorgenesis, mainly due to its modulating effect on p53 by deacetylation on lysine382. A large quantity of SIRT1 inhibitors was applied in chemotherapeutic study, but few of them were applied into clinical trials. METHODS AND RESULTS: In the current study, a novel series of compounds with 1,4-bispiperazinecarbodithioic acid methyl esters scaffold were characterized to have inhibitory potency to SIRT1 by molecular docking and biochemical evaluation. Further cell level study revealed that one of the most potent SIRT1 inhibitors, compound 3a, is cell active. It can upregulate the amount of p53 by accumulating the K382 acetylation of p53, which lead to the stabilization of p53 in human gastric cancer cell line MGC-803 cells. Meanwhile, we also found compound 3a can inactivate SIRT2 in cells, which suggests the compound as a non-selective SIRT inhibitor. CONCLUSION: All these findings indicate that compound 3a is a potent, reversible and cell active SIRT1 inhibitor and deserves further investigation as an anticancer agent or a biological tool.


Subject(s)
Gene Expression Regulation/drug effects , Sirtuin 1/antagonists & inhibitors , Thiocarbamates/pharmacology , Triazoles/pharmacology , Acetylation/drug effects , Binding Sites , Cell Line, Tumor , Enzyme Inhibitors/pharmacology , Humans , Molecular Docking Simulation , Protein Binding/drug effects , Protein Structure, Tertiary , Sirtuin 1/metabolism , Sirtuin 2/antagonists & inhibitors , Sirtuin 2/metabolism , Thiocarbamates/chemistry , Triazoles/chemistry , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism
6.
Anesthesiology ; 124(1): 169-83, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26566282

ABSTRACT

BACKGROUND: Synaptic mechanisms and neuronal oscillations have been proposed to be responsible for neuropathic pain formation. Many studies have also highlighted the important role of electrical synapses in synaptic plasticity and in neuronal oscillations. Thus, electrical synapses may contribute to neuropathic pain generation. However, previous studies have primarily focused on the role of chemical synapses, while ignoring the role of electrical synapses, in neuropathic pain generation. METHODS: The authors adopted microinjection, RNA interference techniques, and behavioral tests to verify the link between connexin 36 (Cx36) and neuropathic pain. They also studied the selective Cx36 blocker mefloquine in rat chronic constriction injury and spared nerve injury model of neuropathic pain. Electrophysiologic recordings were used to further confirm the behavioral data. RESULTS: The authors found that Cx36, which constitutes the neuron-neuron electrical synapses, was up-regulated in the anterior cingulate cortex after nerve injury (n = 5). Meanwhile, Cx36-mediated neuronal oscillations in the gamma frequency range (30 to 80 Hz) (n = 7 to 8) and the neuronal synaptic transmission (n = 13 to 19) were also enhanced. Neuropathic pain was relieved by disrupting Cx36 function or expression in the anterior cingulate cortex. They also found that mefloquine, which are clinically used for treating malaria, affected gamma oscillations and synaptic plasticity, leading to a sustained pain relief in chronic constriction injury and spared nerve injury models (n = 7 to 12). CONCLUSION: The electrical synapses blocker mefloquine could affect gamma oscillations and synaptic plasticity in the anterior cingulate cortex and relieve neuropathic pain. Cx36 may be a new therapeutic target for treating chronic pain.


Subject(s)
Electrical Synapses/drug effects , Gyrus Cinguli/drug effects , Mefloquine/pharmacology , Neuralgia/prevention & control , Animals , Connexins/drug effects , Disease Models, Animal , Gyrus Cinguli/physiopathology , Neuronal Plasticity/drug effects , Neurons/drug effects , Rats , Synaptic Transmission/drug effects , Gap Junction delta-2 Protein
7.
Huan Jing Ke Xue ; 36(6): 1952-8, 2015 Jun.
Article in Chinese | MEDLINE | ID: mdl-26387294

ABSTRACT

In order to understand the pollution situation, as well as seasonal changes in characteristics and speciation of dissolved heavy metals in acid rain control zone, the concentrations of dissolved heavy metals in rainwater collected at Guiyang were measured using inductively coupled plasma mass spectrometry (ICP-MS). And the speciation of dissolved heavy metals was further simulated by PHREEQC model. The results showed that the dissolved Co, Ni, Cu, Zn and Cd concentrations were low and not higher than the national standards for drinking water quality in China. The dissolved Pd concentrations were high in fall and winter and higher than the national standards for drinking water quality in China. The Co and Ni in rainwater mainly came from the crust and there was almost no human impact. The Cu, Zn, Cd and Pd pollutions in rainwater were affected by human activity with different levels. The degrees of contamination in autumn and winter were more serious than those in spring and summer. The free metal ion species was the dominant form of dissolved heavy metal, accounting for 47.27%-95.28% of the dissolved metal in rainwater from Guiyang city. The free metal ion species was followed in abundance by Metal-Oxalate and Metal-sulfate complexes that accounted for 0.72% -51.87% and 0.50%-7.66%, respectively. The acidity of rainwater, acid type as well as content of ligand more likely controlled the distribution of dissolved heavy metal in precipitation.


Subject(s)
Acid Rain , Metals, Heavy/analysis , Water Quality , China , Cities , Environmental Monitoring , Seasons
8.
ASN Neuro ; 7(2)2015.
Article in English | MEDLINE | ID: mdl-25873307

ABSTRACT

Huge body of evidences demonstrated that volatile anesthetics affect the hippocampal neurogenesis and neurocognitive functions, and most of them showed impairment at anesthetic dose. Here, we investigated the effect of low dose (1.8%) sevoflurane on hippocampal neurogenesis and dentate gyrus-dependent learning. Neonatal rats at postnatal day 4 to 6 (P4-6) were treated with 1.8% sevoflurane for 6 hours. Neurogenesis was quantified by bromodeoxyuridine labeling and electrophysiology recording. Four and seven weeks after treatment, the Morris water maze and contextual-fear discrimination learning tests were performed to determine the influence on spatial learning and pattern separation. A 6-hour treatment with 1.8% sevoflurane promoted hippocampal neurogenesis and increased the survival of newborn cells and the proportion of immature granular cells in the dentate gyrus of neonatal rats. Sevoflurane-treated rats performed better during the training days of the Morris water maze test and in contextual-fear discrimination learning test. These results suggest that a subanesthetic dose of sevoflurane promotes hippocampal neurogenesis in neonatal rats and facilitates their performance in dentate gyrus-dependent learning tasks.


Subject(s)
Anesthetics, Inhalation/pharmacology , Dentate Gyrus/drug effects , Discrimination Learning/drug effects , Maze Learning/drug effects , Methyl Ethers/pharmacology , Neurogenesis/drug effects , Animals , Animals, Newborn , Bromodeoxyuridine , Cell Count , Cell Proliferation/drug effects , Cell Survival/drug effects , Dentate Gyrus/growth & development , Dentate Gyrus/physiology , Discrimination Learning/physiology , Fear/drug effects , Fear/physiology , Immunohistochemistry , Male , Maze Learning/physiology , Neurons/drug effects , Neurons/physiology , Patch-Clamp Techniques , Random Allocation , Rats, Sprague-Dawley , Sevoflurane , Tissue Culture Techniques
9.
J Med Chem ; 58(4): 1705-16, 2015 Feb 26.
Article in English | MEDLINE | ID: mdl-25610955

ABSTRACT

Histone lysine specific demethylase 1 (LSD1) was reported to be overexpressed in several human cancers and recognized as a promising anticancer drug target. In the current study, we designed and synthesized a novel series of pyrimidine-thiourea hybrids and evaluated their potential LSD1 inhibitory effect. One of the compounds, 6b, containing a terminal alkyne appendage, was shown to be the most potent and selective LSD1 inhibitor in vitro and exhibited strong cytotoxicity against LSD1 overexpressed gastric cancer cells. Compound 6b also showed marked inhibition of cell migration and invasion as well as significant in vivo tumor suppressing and antimetastasis role, without significant side effects by oral administration. Our findings indicate that the pyrimidine-thiourea-based LSD1 inactivator may serve as a leading compound targeting LSD1 overexpressed cancers.


Subject(s)
Antineoplastic Agents/pharmacology , Drug Design , Enzyme Inhibitors/pharmacology , Histone Demethylases/antagonists & inhibitors , Neoplasms, Experimental/drug therapy , Pyrimidines/pharmacology , Thiourea/pharmacology , Administration, Oral , Animals , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/chemistry , Histone Demethylases/metabolism , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Molecular Structure , Neoplasms, Experimental/metabolism , Neoplasms, Experimental/pathology , Pyrimidines/administration & dosage , Pyrimidines/chemistry , Structure-Activity Relationship , Thiourea/administration & dosage , Thiourea/chemistry
10.
J Med Chem ; 56(21): 8543-60, 2013 Nov 14.
Article in English | MEDLINE | ID: mdl-24131029

ABSTRACT

Lysine specific demethylase 1 (LSD1), the first identified histone demethylase, plays an important role in epigenetic regulation of gene activation and repression. The up-regulated LSD1's expression has been reported in several malignant tumors. In the current study, we designed and synthesized five series of 1,2,3-triazole-dithiocarbamate hybrids and screened their inhibitory activity toward LSD1. We found that some of these compounds, especially compound 26, exhibited the most specific and robust inhibition of LSD1. Interestingly, compound 26 also showed potent and selective cytotoxicity against LSD1 overexpressing gastric cancer cell lines MGC-803 and HGC-27, as well as marked inhibition of cell migration and invasion, compared to 2-PCPA. Furthermore, compound 26 effectively reduced the tumor growth bared by human gastric cancer cells in vivo with no signs of adverse side effects. These findings suggested that compound 26 deserves further investigation as a lead compound in the treatment of LSD1 overexpressing gastric cancer.


Subject(s)
Antineoplastic Agents/pharmacology , Enzyme Inhibitors/pharmacology , Histone Demethylases/antagonists & inhibitors , Stomach Neoplasms/drug therapy , Thiocarbamates/pharmacology , Triazoles/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Histone Demethylases/metabolism , Humans , Mice , Mice, Inbred BALB C , Models, Molecular , Molecular Dynamics Simulation , Molecular Structure , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/pathology , Stomach Neoplasms/pathology , Structure-Activity Relationship , Thiocarbamates/chemistry , Triazoles/chemistry
11.
Pain Physician ; 16(5): E577-89, 2013.
Article in English | MEDLINE | ID: mdl-24077208

ABSTRACT

BACKGROUND: Neuropathic pain induction by nerve injury has been shown by in vitro studies to be accompanied by synaptic strengthening in the anterior cingulate cortex (ACC) and has been shown by pharmacological studies in vivo to be prevented by blocking N-methyl-D-aspartate (NMDA) receptor-dependent ACC plasticity. These findings indicate that ACC neurons undergo nerve injury-induced synaptic modifications and further raise a new question about neuropathic pain-associated changes in neuronal activity in the ACC in vivo, particularly spontaneous neuronal oscillations - a process believed to be fundamental for many forms of brain function. OBJECTIVE: In this study, we examined the change of spontaneous membrane-potential (MP) oscillations in the ACC in vivo in a neuropathic pain animal model of chronic constriction injury (CCI), which may account for neuropathic pain development, as well as pain hypersensitivity and spontaneous pain. STUDY DESIGN: Experimental trial in rats. METHODS: Neuropathic pain rats were produced by CCI surgery on the common sciatic nerve. Neuropathic pain-related behaviors were accessed by evoked responses to both mechanical and thermal stimuli, as well as spontaneous pain indicated by spontaneous foot lifting. In vivo whole-cell recording was performed in both control and neuropathic pain rats under anaesthesia. MP and action-potential (AP) changes of layer II/III ACC pyramidal cells were measured in current-clamp mode. The level of anaesthesia was evaluated by monitoring respiratory and heart rates in some experiments. RESULTS: Within 7 to 14 days after CCI surgery, the frequency of MP oscillations of ACC neurons was found to be significantly higher than that in control rats. Such an increase in oscillation frequency after surgery was not due to periphery transmission via the sciatic nerve subjected to CCI surgery and was indicated to be accounted for by neuronal modifications in the central nervous system. Furthermore, this increase was found to result in a higher overall level of MP excitation as well as an increase in spontaneous AP firing. LIMITATIONS: Our findings in MP and AP changes were obtained in anaesthetized brains; this issue remains to be further examined by using whole-cell recording in awake behaving animals. CONCLUSIONS: Neuropathic pain is accompanied by the increase in rates of spontaneous oscillations of ACC neurons. This change may be critical for neuropathic pain development, as well as pain hypersensitivity and spontaneous pain in neuropathic pain animals.


Subject(s)
Membrane Potentials/physiology , Neuralgia/physiopathology , Neurons/physiology , Sciatic Nerve/physiopathology , Spinal Cord/physiopathology , Animals , Chronic Disease , Constriction , Disease Models, Animal , Male , Patch-Clamp Techniques/methods , Rats , Rats, Sprague-Dawley , Sciatic Nerve/injuries , Synaptic Transmission/physiology , Time Factors
12.
Huan Jing Ke Xue ; 32(4): 936-42, 2011 Apr.
Article in Chinese | MEDLINE | ID: mdl-21717729

ABSTRACT

The odor pollution of landfill is one of seriously pollutions in city ambient area. Main pollution points in the landfill area have been detected by preliminary research. For a particular purpose to recover the materials changing in odor dispersion process and to find out odor indication material, GC-MS method was used to detect materials in the different site at down wind direction. Then, similarity coefficient of VOCs (volatile organic compounds) composition between every two site were calculated and compared to look for changing regular of odor pollution in diffusion process. The odor pollution indictor material has be found in the materials that appeared in down wind direction of operation area and compared its' olfaction threshold. The results show that: there have 19 types of common materials in the landfill area, including monoaromatics, alkanes and halogenated compounds; Materials in the air of operation area site has marked influence on down windward direction air of landfill, and m-xlyene has been selected as odor pollution indictor of landfill air by this research.


Subject(s)
Air Pollutants/analysis , Odorants/analysis , Refuse Disposal , Volatile Organic Compounds/analysis , China , Environmental Monitoring , Gas Chromatography-Mass Spectrometry
13.
Zhonghua Yi Xue Za Zhi ; 90(2): 96-9, 2010 Jan 12.
Article in Chinese | MEDLINE | ID: mdl-20356490

ABSTRACT

OBJECTIVE: To investigate the correlation between the tumor vascular invasion and the change of cardio-pulmonary exercise function in patients with lung cancer. METHODS: The cardio-pulmonary exercise test was performed in 405 patients with lung cancer (293 with vascular invasion and 112 without). The peak load indices examined included maximal work power (measured value/predicted value, W%), maximal oxygen uptake per weight (VO(2)/kg), anaerobic threshold (AT), maximal oxygen pulse (measured value/predicted value, VO(2)/HR%), maximal minute ventilation (V(E)), maximal breath reserve (BR), maximal breath frequency (BF) and maximal tidal volume during expiration (VTex). RESULTS: (1) W%, VO(2)/kg, AT, VO(2)/HR% of patients with vascular invasion [(73 +/- 18)%, (17 +/- 5) ml * min(-1) * kg(-1), (51 +/- 14)%, (79 +/- 18)% respectively] decreased than those without vascular invasion [(86 +/- 20)%, (19 +/- 5) ml * min(-1) * kg(-1), (55 +/- 14)%, (88 +/- 20)% respectively, all P < 0.01) while BF increased [(32.1 +/- 6.1)/min vs (30.6 +/- 5.1)/min, P < 0.05). (2) The patients were divided according to TNM stage, number, kind of tumor vascular invasion and its relationship with tumor, W%, VO(2)/HR% decreased in the groups of 1-, 2- and >or= 3-vessel invasion versus the control group (P < 0.01), AT decreased in the groups of 1- and >or= 3-vessel invasion versus the control group (P < 0.05, P < 0.01), VO(2)/kg decreased in the groups of 2- and >or= 3-vessel invasion versus the control group (P < 0.05, P < 0.01), VO(2)/kg decreased in the group of >or= 3-vessel invasion versus 1- and 2-vessel invasion (P < 0.05 or P < 0.01), VO(2)/HR% decreased in the group of >or= 3-vessel invasion versus 1-vessel invasion (P < 0.01), VTex decreased in the group of >or= 3-vessel invasion versus the control group and 1-vessel invasion (P < 0.05). There was correlation between VO(2)/HR% and the number of tumor invaded vessels (r = 0.220, P < 0.01). CONCLUSIONS: The amount of oxygen uptake, exercise ability and cardiac function during exercise decrease in patients of lung cancer with tumor vascular invasion. The main reason is the number of the invaded vessels.


Subject(s)
Blood Vessels/pathology , Exercise Test , Heart/physiopathology , Lung Neoplasms/pathology , Lung/physiopathology , Adult , Aged , Female , Humans , Lung Neoplasms/physiopathology , Male , Middle Aged , Neoplasm Invasiveness , Neoplasm Staging
14.
Mol Cell Biol ; 29(20): 5389-98, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19687297

ABSTRACT

In all telomerases, the template region of the RNA subunit contains a region of telomere homology that is longer than the unit telomeric repeat. This allows a newly synthesized telomeric repeat to translocate back to the 3' end of the template prior to a second round of telomeric repeat synthesis. In the yeast Kluyveromyces lactis, the telomerase RNA (Ter1) template has 30 nucleotides of perfect homology to the 25-bp telomeric repeat. Here we provide strong evidence that three additional nucleotides at positions -2 through -4 present on the 3' side of the template form base-pairing interactions with telomeric DNA. Mutation of these bases can lead to opposite effects on telomere length depending on the sequence permutation of the template in a manner consistent with whether the mutation increases or decreases the base-pairing potential with the telomere. Additionally, mutations in the -2 and -3 positions that restore base-pairing potential can suppress corresponding sequence changes in the telomeric repeat. Finally, multiple other yeast species were found to also have telomerase RNAs that encode relatively long 7- to 10-nucleotide domains predicted to base pair, often with imperfect pairing, with telomeric DNA. We further demonstrate that K. lactis telomeric fragments produce banded patterns with a 25-bp periodicity. This indicates that K. lactis telomeres have preferred termination points within the 25-bp telomeric repeat.


Subject(s)
Base Pairing/genetics , Kluyveromyces/genetics , RNA/chemistry , RNA/genetics , Telomerase/chemistry , Telomerase/genetics , Telomere/physiology , Base Pairing/physiology , Kluyveromyces/enzymology , RNA/metabolism , Telomerase/metabolism , Telomere/genetics , Yeasts/enzymology , Yeasts/genetics , Yeasts/metabolism
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