Matrix metalloproteinases (MMPs) play an important role in degradation of gastric extracellular matrix proteins. However, no reports are available on the relationship between the activity of MMPs and gastric ulceration induced by alcohol. Our objective was to investigate the effect of melatonin (N-acetyl-5-methoxytryptamine) on the regulation of MMP-9 and MMP-2 activities during prevention of ethanol-induced gastric ulcer. Biochemical and zymographic methods were used to analyze MMP-9 and -2 activities in gastric tissues of Balb/c mice following induction of gastric ulcer by ethanol. Our studies reveal that melatonin arrested cell injury, protein carbonyl formation, and lipid peroxidation in mice during gastroprotection. Melatonin dose-dependently reduced proMMP-9 activity that was induced ( approximately 25-fold) during ethanol-induced gastric ulceration. Severity of gastric ulcers were correlated proportionately with increased dose of ethanol and elevated activity of proMMP-9 and -2. The reduced activities of MMP-9 and -2 were associated with reduced expression of TNF-alpha and increased expression of tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2). We conclude that melatonin's ability to prevent ethanol-induced gastric ulceration in mice is related to a reduction in proMMP-9 activity and expression.

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Kinetoplastids, including Trypanosoma brucei, control gene expression primarily at the posttranscriptional level. Nuclear mRNA export is an important, but understudied, step in this process. The general heterodimeric export factors, Mex67/Mtr2, function in the export of mRNAs and tRNAs in T. brucei, but RNA binding proteins (RBPs) that regulate export processes by controlling the dynamics of Mex67/Mtr2 ribonucleoprotein formation or transport have not been identified. Here, we report that DRBD18, an essential and abundant T. brucei RBP, associates with Mex67/Mtr2 in vivo, likely through its direct interaction with Mtr2. DRBD18 downregulation results in partial accumulation of poly(A)+ mRNA in the nucleus, but has no effect on localization of intron-containing or mature tRNAs. Comprehensive analysis of transcriptomes from whole cell and cytosol in DRBD18 knockdown parasites demonstrates that depletion of DRBD18 leads to impairment of nuclear export of a subset of mRNAs. CLIP experiments reveal association of DRBD18 with several of these mRNAs. Moreover, DRBD18 knockdown leads to a partial accumulation of the Mex67/Mtr2 export receptors in the nucleus. Taken together, the current study supports a model in which DRBD18 regulates the selective nuclear export of mRNAs by promoting the mobilization of export competent mRNPs to the cytosol through the nuclear pore complex.

Kinetoplastids, including Trypanosoma brucei, control gene expression primarily at the posttranscriptional level. Nuclear mRNA export is an important, but understudied, step in this process. The general heterodimeric export factors, Mex67/Mtr2, function in the export of mRNAs and tRNAs in T. brucei, but RNA binding proteins (RBPs) that regulate export processes by controlling the dynamics of Mex67/Mtr2 ribonucleoprotein formation or transport have not been identified. Here, we report that DRBD18, an essential and abundant T. brucei RBP, associates with Mex67/Mtr2 in vivo, likely through its direct interaction with Mtr2. DRBD18 downregulation results in partial accumulation of poly(A)+ mRNA in the nucleus, but has no effect on the localization of intron‐containing or mature tRNAs. Comprehensive analysis of transcriptomes from whole‐cell and cytosol in DRBD18 knockdown parasites demonstrates that depletion of DRBD18 leads to impairment of nuclear export of a subset of mRNAs. CLIP experiments reveal the association of DRBD18 with several of these mRNAs. Moreover, DRBD18 knockdown leads to a partial accumulation of the Mex67/Mtr2 export receptors in the nucleus. Taken together, the current study supports a model in which DRBD18 regulates the selective nuclear export of mRNAs by promoting the mobilization of export competent mRNPs to the cytosol through the nuclear pore complex.

Universal minicircle sequence binding proteins (UMSBPs) are CCHC-type zinc-finger proteins that bind a single-stranded G-rich sequence, UMS, conserved at the replication origins of the mitochondrial (kinetoplast) DNA of trypanosomatids. Here, we report that Trypanosoma brucei TbUMSBP2, which has been previously proposed to function in the replication and segregation of the mitochondrial DNA, colocalizes with telomeres at the nucleus and is essential for their structure, protection and function. Knockdown of TbUMSBP2 resulted in telomere clustering in one or few foci, phosphorylation of histone H2A at the vicinity of the telomeres, impaired nuclear division, endoreduplication and cell growth arrest. Furthermore, TbUMSBP2 depletion caused rapid reduction in the G-rich telomeric overhang, and an increase in C-rich single-stranded telomeric DNA and in extrachromosomal telomeric circles. These results indicate that TbUMSBP2 is essential for the integrity and function of telomeres. The sequence similarity between the mitochondrial UMS and the telomeric overhang and the finding that UMSBPs bind both sequences suggest a common origin and/or function of these interactions in the replication and maintenance of the genomes in the two organelles. This feature could have converged or preserved during the evolution of the nuclear and mitochondrial genomes from their ancestral (likely circular) genome in early diverged protists.

Background:Idiopatiic pulmonary fibrosis (IPF) is a disease of dysregulated fibrogenesis with abnormal matrix metalloproteinase (MMPs) activity, angiogenesis, and profibrotic milieu wherein MMPs inhibition appears to be target-based therapy. We evaluated the role of doxycycline as a nonspecific inhibitor of MMPs in IPF patients.Materials and MethodsPatients of IPF diagnosed on the basis of ATS-ERS consensus criteria were put on oral doxycycline in an open prospective trial. They were followed up for long term with spirometry, 6 min walk test (6MWT), St. Georges respiratory questionnaire (SGRQ), forced vital capacity (FVC), and repeat bronchoscopy while on doxycycline monotherapy for over 24 weeks. Both the initial and follow-up broncho alveolar lavage fluids (BALF) from IPF patients (n = 6) and control subjects (n = 6) were looked for MMP-9, -3, tissue inhibitor of metalloproteinase (TIMP)-1 and vascular endothelial growth factor (VEGF) expression. Additionally, doxycycline's action on MMP activities in vitro was tested in BALF of IPF patients.Results:Doxycycline intervention showed significant improvement in IPF patients in terms of change in 6MWT, SGRQ, FVC, and quality of life. The level of MMP-9, -3, TIMP-1 and VEGF in the BALF were found significantly higher in the IPF patients compared to the controls while doxycycline therapy reduced those parameters nearer to control value. Doxycycline also showed a significant dose-dependent reduction in the in vitro MMPs activities in BALF.Conclusion:Doxycycline shows significant prospect in the treatment of IPF through its anti MMPs activities. This is the first report on a case series of long-term doxycycline monotherapy in IPF patients.

This is the first demonstration of dual action of doxycycline, that is, regulation of MMP activity and reduction of oxidative stress in arresting gastric injury.