Dasgupta, Madhumanti et al. (2019) International Worm Meeting "Nuclear hormone receptor NHR-49 shapes immune-metabolic response of Caenorhabditis elegans to Enterococcus faecalis infection."

Singh, Varsha, Gupta, Anjali, Javed, Salil, Shashikanth, Meghana, Dasgupta, Madhumanti, Bojanala, Nagagireesh

[International Worm Meeting, 2019]

Immune responses to pathogenic microbes include activation of resistance and tolerance mechanisms in the host both of which are energetically expensive. In this study, we show that C. elegans fed on Gram positive bacterium, Enterococcus faecalis rapidly utilize lipid droplets, the major energy reserve in the nematode. Feeding on E. faecalis causes developmental arrest in C. elegans larvae and growth arrest in adults, compared to E. coli diet. We find that nematode's early response to infection entails an increase in expression of 10 genes involved in lipid breakdown as early as 8 hours of exposure, suggesting that neutral lipids are utilized as energy source during E. faecalis infection. Feeding on this pathogen also leads to a concomitant decrease in expression of lipid synthesis genes in C. elegans. We also show that lipid droplets play a protective role in C. elegans during infection. NHR-49, a PPAR? ortholog, is required for E. faecalis induced beta-oxidation of fatty acids and immune effector production and thus regulates an immuno-metabolic axis required for survival of the nematode on E. faecalis.

Ellis HM et al. (1998) East Coast Worm Meeting "C. elegans era, homolog of an E. coli cell cycle gene?"

Golden A, Powell BS, Court DL, Ellis HM

[East Coast Worm Meeting, 1998]

Members of the GTPase superfamily are found in organisms ranging from bacteria to humans. These proteins function as molecular switches, regulating a variety of cellular processes including signal transduction, cell cycle regulation and protein translocation. The E. coli GTPase, ERA (E.coli ras-like) is an essential protein required for normal progression through the cell cycle1. Reduction of era function results in cell cycle arrest after chromosome partitioning, but prior to cytokinesis. Sequence comparisons suggest that ERA and its homologs in other bacteria, C.elegans, mouse and human form a new subfamily of GTPases. These proteins show extensive homology both in the GTPase domain and in a C-terminal region of unknown function. In searches of the C.elegans database with the conserved carboxy-terminal region of E. coli ERA we identified a single homolog, E02H1.2, which we will refer to as Ce-ERA-1. Ce-ERA-1, is 31% identical (49% similar) to E.coli ERA in the GTPase domain and 19% identical (43% similar) to E.coli ERA in the C-terminal region. RT-PCR experiments generated an SL2 spliced cDNA with an exon structure matching that predicted by the genome project. The function of Ce-era-1 is unknown. Attempts to disrupt Ce -era-1 function by RNA-mediated interference did not generate any obvious phenotype. We are currently taking two approaches to the analysis of Ce-era-1 function: 1) Expression of transgenes carrying mutations predicted to produce dominant activated or dominant negative phenotypes. 2) Isolation of null mutations in a PCR based screen for deletions. In addition we have generated polyclonal antibodies against Ce-ERA peptides and will examine the temporal and spatial patterns of Ce-ERA expression. 1. Britton, R.A., Powell, B.S., Dasgupta, S., Sun, Q., Margolin, W., Lupski, J.R., and Court, D.L.(1998) Cell cycle arrest in Era GTPase mutants: a potential growth regulated checkpoint in Escherichia coli. Molecular Microbiology 27(4), 739-750. This work was sponsored by the National Cancer Institute, DHHS, under contract to ABL.

Powell BS et al. (2000) East Coast Worm Meeting "C. elegans era, homolog of an E. coli cell cycle gene?"

Golden A, Ellis HM, Powell BS, Court DL

[East Coast Worm Meeting, 2000]

Members of the GTPase superfamily are found in organisms ranging from bacteria to humans. These proteins function as molecular switches, regulating a variety of cellular processes including signal transduction, cell cycle regulation and protein translocation. The E. coli GTPase, ERA is an essential protein required for normal progression through the cell cycle1. Reduction of era function results in cell cycle arrest after chromosome partitioning, but prior to cytokinesis. Sequence comparisons suggest that ERA and its homologs in other bacteria, C.elegans, mouse and human form a new subfamily of GTPases. These proteins show extensive homology both in the GTPase domain and in a C-terminal RNA binding domain. In searches of the C.elegans database with the conserved carboxy-terminal region of E. coli ERA we identified a single homolog, E02H1.2, which we will refer to as Ce-ERA-1. Ce-ERA-1, is 31% identical (49% similar) to E.coli ERA in the GTPase domain and 19% identical (43% similar) to E.coli ERA in the C-terminal region. RT-PCR experiments generated an SL2 spliced cDNA with an exon structure matching that predicted by the genome project. The first gene in this operon E02H1.1 is homologous to the bacterial rRNA methyltransferase ksgA, which interacts genetically with E. coli era. Thus there might be a functional relationship between the two genes in the C. elegans operon. RNA-mediated interference of E02H1.1 results in a severe developmental delay and larval lethality. The function of Ce-era-1 is unknown. Attempts to disrupt Ce-era-1 function by RNA-mediated interference did not generate any obvious phenotype. A null allele of Ce-era-1 was recently identified in a PCR screen (R. Ranganathan and H.R. Horvitz, personal communication). Characterization of this allele will be presented. 1. Britton, R.A., Powell, B.S., Dasgupta, S., Sun, Q., Margolin, W., Lupski, J.R., and Court, D.L.(1998) Cell cycle arrest in Era GTPase mutants: a potential growth regulated checkpoint in Escherichia coli. Molecular Microbiology 27(4), 739-750.