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Articles by Pappachan E. Kolattukudy
Total Records ( 3 ) for Pappachan E. Kolattukudy
  Marie-Laure Chesne-Seck , Nathalie Barilone , Frederic Boudou , Jesus Gonzalo Asensio , Pappachan E. Kolattukudy , Carlos Martin , Stewart T. Cole , Brigitte Gicquel , Deshmukh N. Gopaul and Mary Jackson
  Similarities between Mycobacterium tuberculosis phoP-phoR mutants and the attenuated laboratory strain M. tuberculosis H37Ra in terms of morphological and cytochemical properties, lipid content, gene expression and virulence attenuation prompted us to analyze the functionality of this two-component regulator in the latter strain. Sequence analysis revealed a base substitution resulting in a one-amino-acid change in the likely DNA-binding region of PhoP in H37Ra relative to H37Rv. Using gel-shift assays, we show that this mutation abrogates the ability of the H37Ra PhoP protein to bind to a 40-bp segment of its own promoter. Consistent with this result, the phoP gene from H37Rv but not that from H37Ra was able to restore the synthesis of sulfolipids, diacyltrehaloses and polyacyltrehaloses in an isogenic phoP-phoR knock-out mutant of M. tuberculosis Moreover, complementation of H37Ra with phoP from H37Rv fully restored sulfolipid, diacyltrehalose and polyacyltrehalose synthesis, clearly indicating that the lack of production of these lipids in H37Ra is solely due to the point mutation in phoP. Using a pks2-3/4 knock-out mutant of M. tuberculosis H37Rv, evidence is further provided that the above-mentioned polyketide-derived acyltrehaloses do not significantly contribute to the virulence of the tubercle bacillus in a mouse model of infection. Reasons for the attenuation of H37Ra thus most likely stand in other virulence factors, many of which are expected to belong to the PhoP regulon and another of which, unrelated to PhoP, appears to be the lack of production of phthiocerol dimycocerosates in this strain.
  Jian Liang , Jing Wang , Asim Azfer , Wenjun Song , Gail Tromp , Pappachan E. Kolattukudy and Mingui Fu
  Activated macrophages play an important role in many inflammatory diseases. However, the molecular mechanisms controlling macrophage activation are not completely understood. Here we report that a novel CCCH-zinc finger protein family, MCPIP1, 2, 3, and 4, encoded by four genes, Zc3h12a, Zc3h12b, Zc3h12c, and Zc3h12d, respectively, regulates macrophage activation. Northern blot analysis revealed that the expression of MCPIP1 and MCPIP3 was highly induced in macrophages in response to treatment with lipopolysaccharide (LPS). Although not affecting cell surface marker expression and phagocytotic function, overexpression of MCPIP1 significantly blunted LPS-induced inflammatory cytokine and Formula production as well as their gene expression. Conversely, short interfering RNA-mediated reduction in MCPIP1 augmented LPS-induced inflammatory gene expression. Further studies demonstrated that MCPIP1 did not directly affect the mRNA stability of tumor necrosis factor α and monocyte chemoattractant protein 1 (MCP-1) but strongly inhibited LPS-induced tumor necrosis factor α and inducible nitric-oxide synthase promoter activation. Moreover, we found that forced expression of MCPIP1 significantly inhibited LPS-induced nuclear factor-κB activation. These results identify MCP-induced proteins, a novel CCCH-zinc finger protein family, as negative regulators in macrophage activation and may implicate them in host immunity and inflammatory diseases.
  Jianli Niu , Asim Azfer , Olga Zhelyabovska , Sumbul Fatma and Pappachan E. Kolattukudy
  Monocyte chemotactic protein-1 (MCP-1) has been recognized as an angiogenic chemokine. The molecular mechanism of MCP-1-mediated angiogenesis remains unknown. We recently identified a novel transcription factor, designated MCP-1-induced protein (MCPIP), in human monocytes after treatment with MCP-1. We investigated whether MCP-1-induced angiogenesis is mediated via MCPIP. Treatment of human umbilical vein endothelial cells (HUVECs) with MCP-1 induced expression of MCPIP and capillary-like tube formation. Knockdown of MCPIP by small interfering RNA (siRNA) suppressed MCP-1-induced angiogenesis-related gene VEGF and HIF-1α expression as well as tube formation. Transfection of HUVECs with an MCPIP expression vector induced angiogenesis-related genes and tube formation. Chromatin immunoprecipitation analysis revealed that cadherin (cdh) 12 and cdh19 are in vivo targets of MCPIP. Transfection of HUVECs with MCPIP expression vector activated the expression of cdh12 and cdh19 genes. Knockdown of cdh12 or cdh19 expression markedly inhibited MCPIP-induced capillary-like tube formation. Moreover, knockdown of MCPIP also significantly suppressed MCP-1-induced cdh12 and cdh19 gene expression. Our data strongly suggest that MCP-1-induced angiogenesis is mediated via MCPIP, at least in part through transcriptional activation of cdh12 and cdh19.
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