Vol 31, Part I - forums.sou.edu • Index page - Southern Oregon ...

ABSTRACTS – Symposia
leading to aggregation and insolubilization. Deamidation, a
prevalent age-related modification in the lens of the eye may
also take place as a result of long term spaceflight, leading
to a decrease in stability of the major lens proteins, crystallins.
Deamidation is loss of a tertiary amino group on an
Asn or Gln resulting in a carboxyl group with a net negative
charge. Nonenzymatic deamidation may be facilitated
by UV exposure. The mechanism of deamidation altering
interactions between the αA-crystallin chaperone and βB2-
crystallin was investigated by thermally inducing complex
formation. Changes in solvent accessibility were detected
by analysis with hydrogen/deuterium exchange coupled
to high-resolution mass spectrometry. The mechanism of
deamidation-dependent mechanisms of cataract formation
through destabilization of crystallins before they can be rescued
by α-chaperone will be discussed.
15 Effects of Simulated Microgravity on Articular Chondrocytes,
Liliana Mellor 1 *, lindsey catlin 1 ,
raquel brown 1 , Warren Knudson 2 , and Julia
Thom Oxford 1 ( 1 Boise State University, Biomolecular
Research Center, Boise, ID 83725; 2 East Carolina University,
Brody School of Medicine, Greenville, NC 27834; lilianamellor@boisestate.edu).
Astronauts experience bone density loss after space flight
resembling osteoporotic conditions due to prolonged exposure
to microgravity. Although bone density loss in space is
a growing field of interest, little is known about the effects
of microgravity on the adjacent articular cartilage. Articular
cartilage of the synovial joints such as hip and knee, are
constantly exposed to mechanical forces produced by daily
activities here on Earth. Similar to bone, cartilage is a type
of connective tissue that requires a balance between synthesis
and degradation of extracellular matrix components to
maintain tissue homeostasis; changes in this balance leads to
cartilage degradation. However, unlike bone tissue, cartilage
lacks innervation, blood supply and cell-cell contact, and has
a very limited regeneration capacity. Proper communication
between individual chondrocytes and the extracellular matrix
is crucial to maintain cartilage homeostasis, and disruption
in cell-matrix interactions can trigger cartilage degradation.
We use two chondrocyte cell lines widely used in arthritis
cell research, RCS (rat chondrosarcoma cells) and C-28/I2
(immortal human chondrocytes), and expose them to a modeled
simulated microgravity environment using a rotating wall
vessel (RWV) bioreactor. We optimized culture conditions for
each cell line in a 3-D environment by testing different microcarriers
and assessing cell viability after several days in the
bioreactor. A better understanding of the molecular signaling
pathways involved in cartilage degradation, will not only help
prevent astronauts developing osteoarthritis from exposure to
microgravity, but will also help us prevent further degradation
in patients experiencing early stages of arthritis on Earth.
16 A Role for PTHrP in Expression of Minor Fibrillar Collagens,
NEDA SHEFA*, MINOTI HIREMATH, and
JULIA THOM OXFORD (Biological Sciences Department,
Boise State University, 1910 University Dr. Boise, ID
83725; nedashefa@boisestate.edu).
Astronauts lose an average of 1-2% in bone mineral
density for every month spent in microgravity. Bone remodeling
is a tightly regulated system that involves formation
of new bone by osteoblasts and resorption of old bone by
osteoclasts. Microgravity uncouples bone remodeling and
causes increased bone resorption. Many attempts have been
made to understand the underlying causes of bone loss in
microgravity but with limited success. Parathyroid hormonerelated
protein (PTHrP) produced by bone cells stimulates
bone formation. Spaceflight causes an 80-90% decrease in
PTHrP mRNA levels. The uncoupling of bone remodeling
in spaceflight could be a downstream effect of decreased
PTHrP. Here, we test the hypothesis of PTHrP acting via collagen
proteins in the extracellular matrix to regulate bone
remodeling. Pre-osteoblasts were treated with PTHrP to
assess the expression of minor fibrillar collagens by reverse
transcriptase PCR. Recent studies show that Col5a3 is specifically
expressed in newly synthesized bone, suggesting
that PTHrP-mediated regulation of Col5a3 may contribute
to new bone formation. Additionally, we treated C2C12
pre-osteoblast cells with BMP-2 to differentiate them into
osteoblasts and then treated them with PTHrP. We observed
that PTHrP also changes the expression of different Col11a1
isoforms in osteoblasts. In summary, our results demonstrate
a crosstalk between PTHrP and the minor fibrillar collagens
that may mediate bone formation during development and
bone remodeling during exposure to microgravity.
17 Interactions of Osteoblasts, Inflammation, and the Extracellular
Matrix in Simulated Free Fall, Jake Goyden*,
Benjamin DAVIS, Julia THOM Oxford, and
Cheryl Jorcyk (Department of Biological Sciences,
Biomolecular Research Center, Musculoskeletal Research,
Boise State University, 1910 University Dr., Boise, ID
83725; jakegoyden@u.boisestate.edu).
Healthy bone repairs damage and adapts to changing
mechanical demands by regulating the balance between bone
destruction by osteoclasts and bone construction by osteoblasts.
In space travel and significant terrestrial diseases like
osteoporosis, bone is lost because osteoblasts activity falls
behind relatively normal osteoclast activity. Osteoblast differentiation
and activity interact with many systems, including
the inflammatory microenvironment and the extracellular
matrix. Sustained free fall in long term spaceflight may
suppress osteoblast function by disrupting these interactions
or alter these systems by disturbing osteoblast function.
We explore the relationships between osteoblasts, inflammation,
the extracellular matrix, and the mechanical environment.
Using the Rotary Cell Culture System, we show how
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