1) The Sox9OXDermo1-Cre model shows no difference in embryo length or mesenchymal condensations compared to controls, but does cause minimal dorsal expression of Sox9 in the trachea. 2) The Bmp4Foxg1-Cre model prevents tracheal specification and development, causing absence of Sox9 expression and increased muscle gene expression in bronchi mesenchyme. 3) The Sox9Foxg1-Cre model inhibits tracheal mesenchymal condensation formation and causes near complete muscle gene expression in bronchi, revealing roles for these genes in tracheal patterning.

1. Results
Figure 1: Comparison of average length of Sox9OXDermo1-Cre
embryos show no significant difference between controls and
mutants. The genotypes for the controls are either Sox9OX or Dermo1-
Cre (2,3,4,etc.). The genotype for the mutants is Sox9OXDermo1-Cre
(1). The length of these embryos was collected because an increase in
cartilage should result in a increase in length. As shown, the average
length of the controls and mutants vary only slightly.
Figure 2: Whole mount
lectin stainings show
no difference in
mesenchymal
condensations between
Sox9OX controls and
mutants. Views of the
ventral (A,C) and dorsal
(B,D) sides of the trachea
show mesenchymal
condensations, which
lead to the formation of
cartilage. There are no
observable differences
between the controls and
the mutants.
Figure 3: Immunofluorescent (IF) stainings of Sox9OX samples show
slight expression of Sox9 in dorsal side of trachea. The antibody aSMA
(red) targets myogenic cells and Sox9 (green) targets chondrogenic cells.
The control (1,2,3) shows only aSMA on the dorsal side of the trachea,
whereas the mutant shows a prescence of aSMA and Sox9 dorsally, for a
slight overexpression of Sox9.
E= esopahgus, T=trachea, S=spine
Understanding The Genetics Underlying Tracheal Patterning and Tracheal Malformations
Introduction
Tracheomalacia is a disorder in which the supportive
cartilaginous rings of the trachea are either severely weakened
or missing, resulting in difficulty breathing, decreased air flow,
and even death. On the other end of the spectrum, Complete
Tracheal Rings (CTR) is a disorder in which the cartilaginous
rings surround most or all of the trachea, resulting in a number
of health problems. The causes of these diseases are
unknown. To date, it has not been determined which genetic
components underline these conditions.
The trachea is formed in a dorsal-ventral pattern, with cartilage
on the ventral side and smooth muscle dorsal. We are
attempting to understand which genes restrict cartilage to the
ventral side of the trachea and smooth muscle to the dorsal
side. We are currently investigating genes that may have a role
in tracheal patterning using transgenic mice. The goal is to
acquire a clearer understanding of the genetics facilitating
these disorders, so that better diagnosis and treatment could
become available.
Results Results
• The Sox9OXDermo1-Cre model does not increase
mesenchymal condensations, but does cause minimal dorsal
expression of Sox9.
• The Bmp4Foxg1-Cre model causes a lack of tracheal
specification and development. However, the bronchi and
lungs are present. Sox9 is absent while myogenic gene
expression is increased in bronchi mesenchyme .
• The Sox9Foxg1-Cre model inhibits formation of
mesenchymal condensations, and causes nearly complete
myogenic gene expression in bronchi, but not in ventral
tracheal mesenchyme.
• The Sox9OXDermo1-Cre model (overexpression of Sox9)
will result in an increase in mesenchymal condensations,
and cause Sox9 to be expressed dorsally in the trachea,
leading to increased tracheal cartilage.
• The Sox9Foxg1-Cre model (deletion of Sox9) will decrease
mesenchymal condensations, leading to decreased tracheal
cartilage and increased tracheal muscle .
• The Bmp4Foxg1-Cre model (deletion of Bmp4) will lead to a
decrease in the expression of Sox9, leading to a decrease
of tracheal cartilage and more tracheal muscle.
Hypotheses
.
Joyce Smith1,3, Kaulini Burra1, Debora Sinner PhD1,2, Division of Neonatology and Pulmonary Biology1, University of Cincinnati College
of Medicine2, Cincinnati Children’s Hospital Medical Center Biomedical Research for Minority Students3
Perinatal Institute
Methods
• Genetically modified mice for the conditional deletion or
overexpression of Sox9 or Bmp4 in mesenchyme of respiratory
tract using the drivers Foxg1-Cre and Dermo1-Cre.
• Collection of embryonic samples and isolation of embryonic
respiratory tract (trachea and lungs).
• Genotyping by Polymerase Chain Reaction (PCR), and
analyzing DNA using agarose gel electrophoresis
• “Crown-Rump” (head to foot, per say) measurements to
compare lengths of embryos.
• Tissue stainings using antibodies and In situ probes that target
specific genes to determine the expression of Chondrogenic
(cartilage) and Myogenic (muscle) genes.
• Whole mount lectin stainings to target and examine
mesenchymal condensations in the trachea.
• Genotypes Analyzed: Sox9OXDermo1-Cre, Sox9Foxg1-Cre,
and Bmp4Foxg1-Cre.
A B
C D
control
Sox9OXDermo1-Cre
CTR
mutant control
Figure 4: Significant phenotypic differences were observed
between Bmp4Foxg1-Cre controls and mutants. The goal of
Bmp4Foxg1-Cre was to delete the gene Bmp4, which is believed to
induce the production of Sox9. Brightfield imaging of embryos show
distinguishable malformations in mutant jawlines and eyes (A,B),
and formation of trachea and lungs (C,D). Lectin stainings show
mesenchymal condensations in controls, but none in mutants.
Figure 5: RNAScope In Situ Hybridization and IF stainings of
Bmp4Foxg1-Cre embryos show lack of trachea and absence of
Sox9 in bronchi of mutants. There is no trachea in the mutants;
however, the lungs and bronchi are present. RNA Scope In Situ
Hybridization staining, using the probe for Myh11 (smooth muscle)
show bronchial patterning in controls (A). IF staining of bronchi
show an increase in smooth muscle cells and absence of Sox9 in
mutants.
E=esophagus, Br=bronchus, BV=blood vessel, L=lung, T=trachea
The Next Steps
• Repeat experiments in mouse models to achieve solid
conclusions of the effects of overexpressing and deleting
Sox9, Bmp4, and Wls, as well as establishing their role in
modulating novel candidate genes in tracheal patterning.
• Collection of human samples of tracheomalacia and CTR.
• Analysis of genes present in human samples and
comparison with genes present in mouse models.
This work was partially
supported by
NIH-NHLBI 1K01HL115447
to DS and by the Office of
Academic Affairs and Career
Development, CCHMC.
Acknowledgements
control
Sox9OXDermo1-Cre
Sox9OXD10 Genotypes
1
S9OX
2 3 4 5 6 7 8 9 10 C1 C2
DCre
Figure 6: Lectin, RNA Scope, and IF stainings of Sox9Foxg1-
Cre samples show no difference in patterning of the trachea,
but significant presence of muscle in bronchi, in mutants.The
goal of Sox9Foxg1-Cre was to delete Sox9 for a tracheomalacia
mouse model. We compared it to a previous tracheomalacia model,
WlsShhCre (Rows 1 and 2), in which we see similar results
(Snowball et.al. 2015). Lectin stainings show complete lack of
mesenchymal condensations in the Sox9Foxg1-Cre samples.
RNAScope stainings show a strong presence of muscle in the
ventral tracheal mesenchyme of WlsShhCre mutants, but not in the
Sox9Foxg1-Cre mutants; however, IF and RNA Scope stainings of
Sox9Foxg1-Cre bronchi show ventral expression of muscle.
Br
Br
BV BV
E
L
control
Bmp4Foxg1-Cre
E
Row 1 Row 2 Row 3
control WlsShhCre Sox9Foxg1-Cre
A B
E
Sox9/aSMA
T
E
T
E
T
BV
BV
BV
Br
Br
Br
Br
E BV
aSMA/Sox9
A B Myh11
aSMA/Sox9/TTF1
E
Br
Br
E
Br
Br
Br
control Bmp4Foxg1-Cre
1 2 3
4 5 6
E
T
E
T
S
control
Sox9OXDermo1-Cre
Conclusions
Bmp4Foxg1-Cre
control
control Bmp4Foxg1-Cre
A
B
C
D
E1
F1
E2 F2
Sox9Foxg1-Cre Sox9Foxg1-Cre