(56f) Effects of Quorum-Signaling Molecules On Human Epithelial Cells: Implications for Interkingdom Response and Communication

Effect of quorum-signaling
molecules on human epithelial cells: Implications for interkingdom response and
communication

Introduction: 
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.

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.