Project description:Receptor-interacting protein kinase 1 (RIP1)-mediated necroptosis plays a vital role in various diseases, but the involvement of RIP1 and its functional mechanism in osteoarthritis pathogenesis remains largely unknown. To identify molecular targets of RIP1 in chondrocytes, RNA sequencing was performed in chondrocytes treated with adenovirus expressing RIP1 or vector control. We found that 9857 genes were differentially expressed in chondrocytes after RIP1 overexpression. GO analysis indicated that DNA replication, chromosome segregation and regulation of cell cycle process were upregulated, while terms including cartilage development, skeletal system development, extracellular matrix organization, skeletal system morphogenesis, chondrocyte differentiation, collagen fibril organization and limb development were downregulated. Pathway analysis revealed that IL-17 signaling pathway, cell cycle, DNA replication, proteasome, TNF signaling pathway, cellular senescence and p53 signaling pathway were significantly upregulated by RIP1, meanwhile, ECM-receptor interaction, other glycan degradation and glycosaminoglycan degradation were downregulated. These results underscore the importance of RIP1 in OA by perturbing a series of essential events during disease progression such like cell cycle regulation, chondrocyte differentiation, inflammation and ECM remodeling.
Project description:Investigation of whole genome gene expression level changes in a Vibrio cholerae O395N1 delta-nqrA-F mutant, compared to the wild-type strain.
Project description:Mycobacterium tuberculosis is exposed to a variety of stresses during a chronic infection, as the immune system simultaneously produces bactericidal compounds and starves the pathogen for essential nutrients. The intramembrane protease, Rip1, plays an important role in the adaptation to these stresses, at least partially by the cleavage of membrane bound transcriptional regulators. Although Rip1 is known to be critical for surviving copper intoxication and nitric oxide exposure, these stresses do not fully account the regulatory protein’s essentiality during infection. In this work, we demonstrate that Rip1 is also necessary for growth in low iron and zinc conditions, similar to those imposed by the immune system. Using a newly generated library of sigma factor mutants, we show that the known regulatory target of Rip1, SigL, shares this defect. Transcriptional profiling under iron limiting conditions supported the coordinated activity of Rip1 and SigL and demonstrated that the loss of these proteins produces an exaggerated iron starvation response. These observations demonstrate that Rip1 coordinates several aspects of metal homeostasis and suggest that a Rip1- and SigL-dependent pathway is involved in the adaptation to the iron deficient environments encountered during infection.
Project description:Vibrio campbellii BB120 (ATCC BAA-1116, previously designated as Vibrio harveyi) is a fundamental model strain for studying population density-based cell-to-cell communication, known as quorum sensing, among gram-negative bacteria. In V. campbellii BB120, sensing of autoinducers at high cell densities activates the expression of the master transcriptional regulator, LuxR, which controls the expression of genes involved in group behaviors. Unlike BB120, the Vibrio campbellii environmental isolate DS40M4 was recently shown to be capable of natural transformation, a process by which bacteria take up exogenous DNA and incorporate it into their genome via homologous recombination. Here, we compare other phenotypes between DS40M4 and BB120. We find that DS40M4 has a faster growth rate and stronger type VI secretion-mediated cell killing, whereas BB120 forms more robust biofilms and is bioluminescent. We exploited the power of natural transformation to rapidly generate >30 mutant strains to explore the function of DS40M4-encoded homologs of the BB120 quorum-sensing system. Our results show that DS40M4 has a similar quorum-sensing circuit to BB120 but with three distinct differences: 1) DS40M4 lacks the canonical HAI-1 autoinducer LuxM synthase but has an active LuxN receptor, 2) the quorum regulatory small RNAs (Qrrs) are not solely regulated by autoinducer signaling through the response regulator LuxO, and 3) the DS40M4 LuxR regulon is <100 genes, which is relatively small compared to the >400 genes regulated in BB120. This work illustrates that DS40M4 is a tractable and relevant model strain for studying quorum-sensing phenotypes in Vibrio campbellii.
Project description:Investigation of whole genome gene expression level changes in a Vibrio cholerae O395N1 delta-nqrA-F mutant, compared to the wild-type strain. Total RNA recovered from wild-type cultures of VIbrio cholerae O395N1 and its nqrA-F mutant strain. Each chip measures the expression level of 3,835 genes from Vibrio cholerae O1 biovar eltor str. N16961 with twenty average probes/gene, with five-fold technical redundancy.