1. The study examined the role of the integrin INA-1 in axonal patterning in C. elegans. 2. Most ina-1 mutants showed errors in GABAergic and cholinergic axon projections. 3. A mutant with wildtype INA-1 also showed many misprojected axons, suggesting INA-1 may not act cell autonomously in GABAergic neurons.

1. Examination of ina-1 Mutants in Caenorhabditis Elegans to Better Understand Axonal Patterning
Priya Ahluwalia, Mary Gonring, Cassie Lincoln, M.L. Lemons
Department of Natural Sciences, Assumption College, Worcester MA 01609
1. INA-1 is expressed in all GABAergic neurons.
2. Most ina-1 (gm39) mutants have axonal errors.
3. ina- 1 (gm144) mutant with wildtype INA-1
shows many misprojected axons suggesting
INA-1 may not act cell autonomously in
GABAergic neurons.
L1
2. Most ina-1(gm39) mutants have ACh and
GABAergic axon pattern defects!
30Percent growth cone collapseE.Netrin-1 Ab0102030Percent growth cone collapseNetrin-1.
3. Preliminary data suggests that INA-1
may not work cell autonomously!
Percentage of
worms with
cholinergic
(ACH, green) or
GABA (red)
axonal errors in
ina-1(gm39)
(N=15). j
INTRODUCTION
Worm strains: Bristol N2 Caenorhabditis elegans were used for this studies . The following
strains were used :ufis34;visis48, ufis34 (unc-47::mCherry); vsis48 (unc-17::GFP); ina-1
(gm144); ufis34;visis48 ina-1 (gm39); ufis34;vsis48, gmIs5 (INA-1::GFP), ufex530
(unc-47::ina-1, unc-47::mCherry, lgc::GFP) ; oxis-12 (unc-47::GFP).
MATERIALS AND METHODS
BACKGROUND
30Percent growth cone collapseE.Netrin-1 Ab0102030Percent growth cone collapseNetrin-1
A.
C.elegans as a model to study neuronal growth
A. Image of the 1 mm nematode
Caenorhabditis elegans.. B.
Cartoon of integrin molecule
with an alpha subunit (purple)
and a beta subunit (orange).
The carton on the left
represents an inactivated
integrin and the image on the
right is an integrin in the
activated, high ligand affinity
state.
RESULTS
30Percent growth cone collapseE.Netrin-1 Ab0102030Percent growth cone collapseNetrin-1
Figure 1.
Fluorescent images
of INA-1 (green) and
GABA neurons (red)
in vivo. Neuronal cell
bodies (that appear
as ovals) are located
in the ventral nerve
cord.
1. INA-1 is expressed in GABAergic Neurons!
INA-1::GFP
GABA
Merge
30Percent growth cone collapseE.Netrin-1 Ab0102030Percent growth cone collapseNetrin-1.
Future Directions
Figure 4: Inactive and
active integrin. PAT-3, a
beta subunit which causes
an integrin to be constantly
active. The future plan is to
make a pat-3 transgenic
mutant that has constant
expression of PAT-3.
30Percent growth cone collapseE.Netrin-1 Ab0102030Percent growth cone collapseNetrin-1.
2. Abnormal axonal projection in ina-1(gm39)
mutants
A."
B"
30Percent growth cone collapseE.Netrin-1 Ab0102030Percent growth cone collapseNetrin-1
The ability of neurons to properly extend axons during development by a complex extracellular
milieu and ultimately reach their appropriate targets is remarkable. The molecular mechanisms
that drive this impressive navigational feat are not yet fully understood. Previous studies
suggest that a family of transmembrane heterodimeric proteins, called integrins, play an
important role in neuronal motility. A functional integrin has two subunits: 1) an alpha subunit,
such as INA-1 and 2) a beta subunit, such as PAT-3. We chose to more fully characterize the
effects of integrins on axon patterning in the genetically-powerful model organism
Caenorhabditis elegans (C.elegans). The focus of our study was to: 1) determine which axons
express INA-1, 2) better understand the role of integrins in axonal patterning and 3) study if
INA-1 works cell autonomously in GABA motor neurons. The future direction of our study will
be to better classify the role of integrin activation (a conformational change to a high ligand
affinity state) on axon guidance.
C"
A"
A. Image of GABA (red) and cholinergic (green) neurons in an ina-1(gm39)
mutant. Neuron cell bodies are located in the ventral nerve cord (bottom). Axons
project from the ventral nerve cord to the dorsal nerve cord. B. Higher
magnification of a wild type axon. Note the straight projection from ventral nerve
cord to dorsal nerve cord. C. Image of ina-1(gm39) mutant worm with abnormal
projection, as indicated by arrows.
Wildtype ina-1(gm39) mutant
GABAergic neuron GABAergic!neurons!
ina-1(gm39) mutant
ina- 1 (gm144) mutant with wildtype INA-1A"
B"
Ina-1 (gm144) mutant
ina- 1 (gm144) mutant with wildtype
INA-1
Ina-1 (gm144) mutant
A. Image of GABA (red) and GABA (green) neurons in ina- 1 (gm144) mutant with
wildtype INA-1 worm. B. Image of the same worm as A GABA (red) neurons in ina-
1 (gm144) mutant with wildtype INA-1 worm. C. Abnormal axon projection in
ina-1(gm144) mutant, as indicated by arrows. D. Axon misprojection in ina- 1
(gm144) mutant with wildtype INA-1, as indicated by arrows.
B"
ina-1(gm144) mutantC" D"
Cholinergic!!GABAergic
A"
B.
ina- 1 (gm144) mutant with wildtype INA-1
0!
10!
20!
30!
40!
50!
60!
70!
80!
90!
100!
Percentage"of"Worms"With"
Axonal"Errors"(%)"
CONCLUSIONS
Diagram!taken!from:!h<p://www.kAstate.edu/hermanlab/!