What's new for 'Trypanosomatids' in PubMed

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Sent on Saturday, 2009 Dec 19
Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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PubMed Results

Items 1 -3 of 3

1.	J Immunol. 2009 Dec 14. [Epub ahead of print] Mice with a Selective Impairment of IFN-{gamma} Signaling in Macrophage Lineage Cells Demonstrate the Critical Role of IFN-{gamma}-Activated Macrophages for the Control of Protozoan Parasitic Infections In Vivo. Lykens JE, Terrell CE, Zoller EE, Divanovic S, Trompette A, Karp CL, Aliberti J, Flick MJ, Jordan MB. Division of Immunobiology. IFN-gamma has long been recognized as a cytokine with potent and varied effects in the immune response. Although its effects on specific cell types have been well studied in vitro, its in vivo effects are less clearly understood because of its diverse actions on many different cell types. Although control of multiple protozoan parasites is thought to depend critically on the direct action of IFN-gamma on macrophages, this premise has never been directly proven in vivo. To more directly examine the effects of IFN-gamma on cells of the macrophage lineage in vivo, we generated mice called the "macrophages insensitive to IFN gamma" (MIIG) mice, which express a dominant negative mutant IFN-gamma receptor in CD68(+) cells: monocytes, macrophages, dendritic cells, and mast cells. Macrophage lineage cells and mast cells from these mice are unable to respond to IFN-gamma, whereas other cells are able to produce and respond to this cytokine normally. When challenged in vitro, macrophages from MIIG mice were unable produce NO or kill Trypanosoma cruzi or Leishmania major after priming with IFN-gamma. Furthermore, MIIG mice demonstrated impaired parasite control and heightened mortality after T. cruzi, L. major, and Toxoplasma gondii infection, despite an appropriate IFN-gamma response. In contrast, MIIG mice displayed normal control of lymphocytic choriomeningitis virus, despite persistent insensitivity of macrophages to IFN-gamma. Thus, the MIIG mouse formally demonstrates for the first time in vivo, the specific importance of direct, IFN-gamma mediated activation of macrophages for controlling infection with multiple protozoan parasites.
	PMID: 20018611 [PubMed - as supplied by publisher]

2.	J Biol. 2009 Dec 14;8(11):100. [Epub ahead of print] Coordinated gene expression by post-transcriptional regulons in African trypanosomes. Ouellette M, Papadopoulou B. Centre de Recherche en Infectiologie and Département de Microbiologie-Infectiologie et Immunologie, Université Laval, Québec, G1V 4G2, Canada. Marc.Ouellette@crchul.ulaval.ca. ABSTRACT: The regulation of gene expression in trypanosomes is unique. In the absence of transcriptional control at the level of initiation, a subset of Trypanosoma brucei genes form post-transcriptional regulons in which mRNAs are co-regulated in response to differentiation signals.See research articles http://www.biomedcentral.com/1471-2164/10/427, http://www.biomedcentral.com/1471-2164/10/482 and http://www.biomedcentral.com/1471-2164/10/495.
	PMID: 20017896 [PubMed - as supplied by publisher]

3.	Biochem J. 2009 Dec 18. [Epub ahead of print] Discovery of functional motifs in h-regions of trypanosome signal sequences. Duffy J, Patham B, Mensa-Wilmot K. N-terminal signal peptides direct secretory proteins into the endoplasmic reticulum (ER) of eukaryotes or the periplasmic space of prokaryotes. A hydrophobic core (h-region) is important for signal sequence function; however, the mechanism of h-region action is not resolved. To gain new insight about signal sequences, bioinformatic analysis of h-regions from humans, Saccharomyces cerevisiae, Trypanosoma brucei, and Escherichia coli was performed. Each species contains a unique set of peptide motifs (h-motifs) characterized by identity components (i.e. sequence of conserved amino acids) joined by spacers. Human h-motifs have four identity components, while those from the other species utilize three identity components. Example of h-motifs are human Hs3, (L-x(2)-[AGILPV]-L-x(0,2)-L); S. cerevisiae Sc1, L-x(0,2)-S-x(0,3)-A; T. brucei Tb2, L-x(1,2)-L-[AILV]; and E. coli Ec1, A-x(0,2)-L-x(0,3)-A. The physiological relevance of h-motifs was tested with a T. brucei microsomal system for translocation of a VSG-117 signal peptide. Disruption of h-motifs by scrambling of sequences in h-regions produced defective signal peptides, although the hydrophobicity of the peptide was not altered. We conclude that (i) h-regions harbor h-motifs, and are not random hydrophobic amino acids; (ii) h-regions from different species contain unique sets of h-motifs; and (iii) h-motifs contribute to the biological activity of ER signal peptides. h-Regions are "scaffolds" in which functional h-motifs are embedded. A hypothetical model for h-motif interactions with a Sec61p protein translocon is presented.
	PMID: 20017734 [PubMed - as supplied by publisher]