Download Breton - Blumberg Lab

Gut Commensal E. coli
Proteins Activate Host
Satiety Pathways following
Nutrient-Induced Bacterial
Growth
{
Breton J, et al.
2016
Brenda Quijas
Background Information:

Bacterial Growth Life Cycle
Background Information/Terms:

Anorexigenic = loss of appetite


Caseinolytic protease B (ClpB) is a recently discovered
E. coli protein




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Orexigenic is the antonym
It mimics the α-melanocyte-stimulating hormone (α-MSH)
α-MSH causes satiety in host organism
POMC = proopiomelanocortin in the hypothalamus
Glucagon-like peptide (GLP-1) is a satietogenic
hormone secreted by α-MSH pathway
Peptide YY (PYY) is another satietogenic hormone
The Purpose of the Study:

To gain insight as to whether
different cell growth phases,
exponential or stationary, can
secrete proteins that will affect the
host organism’s satiety, or appetite.
E. coli growth dynamics In Vitro
studies
E. coli K12 was used
because it modeled gut
bacteria
 Optical Density gave an
idea of bacterial growth
 Two-dimensional
polyacrylamide gel
electrophoresis



assessed separately
membrane (Exp) and
cytoplasmic (Stat) fractions
MS/MS peak lists gave
protein identification
ATP production In Vitro Experiment

An ATP assay was
used to measure
bacterial energy
extraction
capacities

No significant
differences were
found
Evidence for Increase in ClpB
production in Stat phase

Enzyme-linked
immunosorbent
assay (ELISA)



whether ClpB
production varies in
the two growth
stages
Western blotting also
used
Both techniques
show a significantly
higher ClpB mean
level in Stat
In Vivo E. coli growth studies in Mice
Verify if bacteria
could affect the
organism’s gut
 The standard was T0
 Blood and fecal
samples were
assessed.

Evidence for short-term
appetite control
E. coli Proteins and their effect
on food intake
Stat phase
decrease intake by
an hour
 Exp phase increase
intake by 4 hours

Neurological Effects:

Immunohistochemical study of c-Fos
expression

studied antigen-antigen binding in brain
for the proto-oncogene.
c-Fos expression leads to
anorexigenic neurons

c-Fos positive expression increase lead to
a decrease in food intake
Chronic Administration of
E. coli proteins in Mice

Mice were given two daily injections (light and
dark)
PBS (control)
 Exp E. coli proteins
 Stat E. coli proteins

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*** = p <0.001 and ** = p <0.01
Satiety ratios on time intervals:

Exp bacterial proteins increased food
intake in the light (morning)

but decreased in the dark (6:00 afternoon)
Satiety ratios

The Stat bacterial proteins increased satiety
ratios and lead to an increase in post meal
intervals.

then a significant decrease in satiety ratios by
the end of the week
Electrophysiological Recordings

Analyzed whether bacterial proteins directly
activated brain circuitry

used an electrophysiological approach

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cell-attached patch-clamping to measure the POMC
neurons’ firing rate
ClpB did lead to an increase in action potentials.
Conclusion:
E. coli bacterial growth stages do
play a key role in satiety of the host
organism
 Stat E. coli proteins lead to a quicker
satiety response, but also an
increase in food intake


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These proteins lead to an increase in
PYY hormone secretion
Bacterial proteins in the gut lead to a
neurological pathway activation
Other Relevant Articles:
Tennoune N, et al. 2015. “Sex-related effects of
nutritional supplementation of Escherichia coli:
Relevance to eating disorders.” Nutrition. 31:
498-507.
 Shetty R.A., et al. 2017. “Immediate and delayed
anxiety- and depression-like profiles in the
adolescent Wistar-Kyoto rat model of
endogenous depression following postweaning
social isolation.” Behavioural Brain Research.
320: 323-332.
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