ABSTRACT
Heme oxygenase-1 (HO1) is a heme-catabolizing enzyme induced by a variety of stress conditions. This article described the cloning and characterization of BrHO1 gene which codes for a putative HO1 from Chinese cabbage (Brassica rapa subsp. pekinensis). BrHO1 consists of three exons and encodes a protein precursor of 32.3 kD with a putative N-terminal plastid transit peptide. The amino acid sequence of BrHO1 was 84% similar to Arabidopsis counterpart HY1. The three-dimensional structure of BrHO1 showed a high degree of structural conservation compared with the known HO1 crystal structures. Phylogenetic analysis revealed that BrHO1 clearly grouped with the HO1-like sequences. The recombinant BrHO1 protein expressed in Escherichia coli was active in the conversion of heme to biliverdin IXα (BV). Furthermore, the results of subcellular localization of BrHO1 demonstrated that BrHO1 gene product was most likely localized in the chloroplasts. BrHO1 was differently expressed in all tested tissues and could be induced upon osmotic and salinity stresses, cadmium (Cd) exposure, hydrogen peroxide (H(2)O(2)), and hemin treatments. Together, the results suggested that BrHO1 plays an important role in abiotic stress responses.
Subject(s)
Brassica rapa/enzymology , Heme Oxygenase-1/isolation & purification , Heme Oxygenase-1/metabolism , Amino Acid Sequence , Biliverdine/metabolism , Brassica rapa/genetics , Chloroplasts/enzymology , Cloning, Molecular , Escherichia coli/genetics , Escherichia coli/metabolism , Heat-Shock Response , Heme/metabolism , Heme Oxygenase-1/chemistry , Heme Oxygenase-1/genetics , Hemin/pharmacology , Hydrogen Peroxide/pharmacology , Molecular Sequence Data , Phylogeny , Sequence Alignment , Sequence Analysis, DNAABSTRACT
Heme oxygenase (HO, EC 1.14.99.3) catalyzes the oxidation of heme and performs vital roles in plant development and stress responses. Two HO isozymes exist in plants. Between these, HO-1 is an oxidative stress-response protein, and HO-2 usually exhibited constitutive expression. Although alfalfa HO-1 gene (MsHO1) has been investigated previously, HO2 is still poorly understood. In this study, we report the cloning and characterization of HO2 gene, MsHO2, from alfalfa (Medica sativa L.). The full-length cDNA of MsHO2 contains an ORF of 870 bp and encodes for 290 amino acid residues with a predicted molecular mass of 33.3 kDa. Similar to MsHO1, MsHO2 also appears to have an N-terminal transit peptide sequence for chloroplast import. Many conserved residues in plant HO were also conserved in MsHO2. However, unlike HO-1, the conserved histidine (His) required for heme-iron binding and HO activity was replaced by tyrosine (Tyr) in MsHO2. Further biochemical activity analysis of purified mature MsHO2 showed no HO activity, suggesting that MsHO2 may not be a true HO in nature. Semi-quantitative RT-PCR confirmed its maximum expression in the germinating seeds. Importantly, the expression levels of MsHO2 were up-regulated under sodium nitroprusside (SNP) and H(2)O(2) (especially) treatment, respectively.
Subject(s)
Cloning, Molecular , Heme Oxygenase (Decyclizing)/chemistry , Heme Oxygenase (Decyclizing)/genetics , Medicago sativa/enzymology , Plant Proteins/chemistry , Plant Proteins/genetics , Amino Acid Sequence , Heme Oxygenase (Decyclizing)/metabolism , Medicago sativa/chemistry , Medicago sativa/classification , Medicago sativa/genetics , Molecular Sequence Data , Phylogeny , Plant Proteins/metabolism , Plants/chemistry , Plants/classification , Plants/enzymology , Plants/genetics , Sequence AlignmentABSTRACT
OBJECTIVE: To investigate the expression of cyclin A protein in childhood acute leukemia (AL) and its significance. METHODS: By using Western blotting analysis, cyclin A protein in bone marrow mononuclear cells from 47 newly diagnosed AL children and 33 non-hematological malignancy children was detected. RESULTS: The expression of cyclin A in AL group (0.38 +/- 0.20) was higher than that in control group (0.03 +/- 0.15) (P < 0.01). The expression of cyclin A in high risk acute lymphocyte leukemia (ALL) group (HR-ALL) (0.62 +/- 0.38) was higher than that in standard risk ALL group (SR-ALL) (0.33 +/- 0.33) (P < 0.05). The expression of cyclin A in WBC > or = 50 x 10(9)/L group and in WBC < 50 x 10(9)/L group was (0.64 +/- 0.36) and (0.39 +/- 0.38), respectively (P < 0.05). Eight (44.4%) out of 18 patients with positive cyclin A expression achieved complete remission (CR). The CR rate was lower than that of patients with negative cyclin A expression (100%) (P < 0.01). CONCLUSIONS: The higher expression of cyclin A may predict a poor prognosis for childhood ALL.
Subject(s)
Cyclin A/metabolism , Leukemia/metabolism , Acute Disease , Adolescent , Child , Child, Preschool , Cyclin A/genetics , Female , Humans , Infant , MaleABSTRACT
OBJECTIVE: To study the DNA synthesis in the airway cells of asthmatic rats after allergen stimulation in association with airway remodeling. METHODS: Double staining immunohistochemical techniques was used to determine DNA synthesis of the airway cells of 12 asthmatic and 12 normal rats. BrdU incorporation into the airway smooth muscle (ASM) and epithelium was quantified by employment of computer-assisted image analysis. RESULTS: BrdU indices in both the ASM and the epithelium of asthmatic model group were higher than those of the control group (P<0.01, P<0.05), and positive linear correlation of the BrdU indices in the ASM and epithelium with the airway diameter was observed (r=0.7828, P<0.01; r=0.5852, P<0.05), which was not found in the control group (r=-0.3755, P>0.05; r=-0.5208, P>0.05). The epithelial thickness of the model group was significantly greater than that of the control group (P<0.01). There was no significant difference in terms of airway diameter, thickness of the ASM and the area positive of alpha-smooth muscle actin between the 2 groups (P>0.05). CONCLUSION: Increased DNA synthesis and accelerated proliferation of ASM and epithelial cells in sensitized SD rats following repeated allergen challenges may lead to airway remodeling.
