LRP1 endocytosis is regulated by KIF13B through the interaction with hDLG1
Abstract: KIF13B, a
kinesin-3 family motor, was originally identified by virtue of its biochemical
interaction with human homolog of Drosophila discs large tumor suppressor (hDLG1).
Unlike its homolog KIF13A, the KIF13B contains a carboxyl-terminal CAP-Gly domain. To
investigate the specific functional role of the CAP-Gly domain in KIF13B, and its
possible compensation by KIF13A, we developed... read moretwo mouse models. One mouse model
expresses a truncated form of KIF13B protein lacking only its CAP-Gly domain
(KIF13BΔCG), whereas the second model lacks the full-length KIF13A (KIF13A FLKO).
Using these mouse models, we show that the KIF13BΔCG mice exhibit relatively
higher levels of serum cholesterol consistent with the reduced uptake of [3H]CO-LDL in
KIF13BΔCG mouse embryo fibroblasts. In contrast, the serum level of factor VIII
was not significantly elevated in the KIF13BΔCG as compared to wild-type mice,
suggesting that the CAP-Gly domain of KIF13B selectively regulates Low density
lipoprotein Related Protein 1-mediated lipoprotein endocytosis. No elevation of either
serum cholesterol or factor VIII was observed in the KIF13A FLKO. Moreover, we found
that the deletion of the CAP-Gly domain caused subcellular mislocalization of truncated
KIF13B with concomitant mislocalization of LRP1. To further delineate the biochemical
basis of the LRP1-KIF13B complex at the plasma membrane, we discovered that the
cytoplasmic domain of LRP1 interacts specifically with the alternatively spliced I3
domain of hDLG1, which in turn recognizes the MBS domain of KIF13B. Together, this study
provides evidence for the biochemical basis of LRP1-hDlg1-KIF13B complex formation,
which regulates LRP1-mediated interactions with implications in metabolism, cell
polarity, and development.
Thesis (Ph.D.)--Tufts University, 2018.
Submitted to the Dept. of Cellular & Molecular Physiology.
Advisors: Laura Liscum, and Athar Chishti.
Committee: Peter Juo, Brent Cochran, and Ronald Dubreuil.
Keywords: Cellular biology, Biochemistry, and Molecular biology.read less