(564a) Effect of Quorum-Signaling Molecules On Human Epithelial Cells: Implications for Interkingdom Response and Communication

It has been
established that bacteria use quorum sensing molecules to coordinate gene
expression in a cell density-dependent manner.   This group of cell communication
molecules is displayed throughout the bacterial hierarchy influence
characteristics such as swarming motility, biofilm formation, virulence, among
others.  A distinct class of
signaling molecules, autoinducer-2, is capable of interspecies communication,
and is so prevalent throughout the bacterial domain that it is thought to be a
"universal" signaling molecule.  While
the mechanisms behind autoinducer-2 have been clearly elucidated, the
interkingdom relationship between quorum signaling molecules and human cells
are not yet understood.  This
relationship is of particular importance considering the many species of
bacteria that constitute the microflora inside the
intestine.  In this study, we
explore the effects of autoinducer-2 on gene expression of human epithelial
cells using the next-generation RNA-seq. 

Human epithelial cells, HCT-8, are
exposed to BL21, a wild-type bacteria that produce AI-2, and a BL21 LuxS knockout that does not produce AI-2.  The RNA is extracted and is sequenced in
triplicate on two lanes of the Illumina HiSeq1000
Sequencing System.  Over 100 million reads for each
condition per biological replicate were analyzed using the Tuxedo Suite
(Bowtie, Tophat & Cufflinks).  With 90% alignment, a total of 318
differentially expressed genes and 8773 differentially expressed isoforms were
found.  Gene clustering analysis
using DAVID ( Database for Annotation, Visualization and Integrated Discovery)
led to significant 28 gene clusters and three signaling pathways through
Signaling Pathway Impact Analysis.

With the
advancements of next generation RNA-Seq technology,
sequencing of the eukaryotic transcriptome is now possible with newfound depth
and breadth, to determine eukaryotic responses.  In this study, transcriptional and
post-transcriptional differential processing was explored and biological
network paths were inferred to indicate response.  Reinforced with this understanding,
two-way interkingdom communication can potentially be mediated with genetically
engineered bacteria that can act on eukaryotic response mechanisms.