Functional Analysis of Cytoskeletal Protein Dematin in Glucose Metabolism.
Abstract: Dematin, a
membrane-cytoskeleton associated actin-binding protein, is known to bind to human
erythrocyte membrane glucose transporter, GLUT1/SLC2A1, and hence may attach and
stabilize the GLUT1 to the spectrin-actin network. The headpiece domain of dematin
contains actin-binding and cAMP-kinase phosphorylation sites, which are required for the
stability of erythrocyte membrane. Dema... read moretin also serves as a substrate of calpain-1, a
cysteine protease that regulates insulin response, but is not known for its influence on
GLUT1 interaction or glucose metabolism. We hypothesized that dematin functions as a key
player in regulating glucose homeostasis through its potential binding partners.
Therefore, we put dematin headpiece domain null (HPKO) mice on high fat diet (n=5 per
genotype) and normal diet (n=4 per genotype) together with the wild type (WT) control
from week 4 for 18 weeks. Glucose metabolic status was examined by monitoring weekly
body weight and blood glucose measurements, and glucose tolerance test (GTT) was
performed in week 19 followed by the insulin tolerance test (ITT) in week 22. Moreover,
we screened human fetal liver cDNA phage display library using dematin as bait. HPKO
mice exhibited unaltered body weight and blood glucose while maintaining similar glucose
and insulin tolerance in both diet groups. From the phage display screen, 38 individual
plaques were picked, 16 sequenced, and 6 functional proteins were identified from the
blast search. From these screens, the AdipoR1 was identified as a promising binding
target for dematin with functional implications on glucose metabolism. These finding
suggest that the headpiece domain might not directly contribute to dematin's role in in
vivo glucose homeostasis. Our results also provide new mechanistic insights into the
role of full-length dematin in regulation of glucose homeostasis via engaging with the
Thesis (M.S.)--Tufts University, 2015.
Submitted to the Dept. of Pharmacology & Experimental Therapeutics.
Advisor: Athar Chishti.
Committee: Margery Beinfeld, and Emmanuel Pothos.
Keyword: Pharmacology.read less