Pitt Logo LinkContact Us

CLATHRIN-MEDIATED ENDOCYTOSIS OF YOLK PROTEIN IN THE DROSOPHILA OOCYTE

JHA, ANUPMA (2011) CLATHRIN-MEDIATED ENDOCYTOSIS OF YOLK PROTEIN IN THE DROSOPHILA OOCYTE. Doctoral Dissertation, University of Pittsburgh.

[img]
Preview
PDF - Primary Text
Download (7Mb) | Preview

    Abstract

    The developing egg chamber of Drosophila accumulates yolk protein to utilize during embryonic development. Egg chamber development is divided in 14 different stages, yolk protein endocytosis occurs between stages 8-11. Yolk protein is present in hemolymph, and the ovaries are bathed in hemolymph. Yolk protein forms a complex with Yolkless for endocytosis in oocyte. Yolkless is an LDL receptor superfamily member, and its cytosolic tail contains the signal for internalization by clathrin-mediated endocytosis. The Yolkless cytosolic tail harbors an typical FxNPxA sequence instead of the commonly found tyrosine-based sorting signal FxNPxY. The tyrosine-based sorting signals interact with PTB domain-containing proteins. In the present study, I show that PTB domaincontaining phagocytic protein Ced-6 is expressed in the cortical region of oocyte of the egg chamber. Ced-6 harbors all the biochemical properties of clathrin-associated sorting proteins. Ced-6 can physically interact with clathrin, AP-2 and phosphoinositide(4,5)P2. The Ced-6 PTB domain interacts with the cytosolic tail of Yolkless and clusters Yolkless into clathrin-coated pit. This clustering leads to internalization of Yolkless by clathrinmediated endocytosis. In conjunction with the FxNPxA signal, Yolkless cytosolic tail contains a functional, although atypical, dileucine signal. This atypical dileucine signal can physically interact with AP-2. This interaction leads to the clathrin-mediated endocytosis of Yolkless. Clathrin adaptor AP-2 and Ced-6 function redundantly in yolk protein uptake, as Ced-6-null flies accumulate yolk protein. Results from this study led to a model where both AP-2 and Ced-6 interact with Yolkless independently to ensure its internalization. Interaction of Ced-6 with clathrin and AP-2 leads to effective clustering of Yolkless for internalization by clathrin-mediated endocytosis.


    Share

    Citation/Export:
    Social Networking:

    Details

    Item Type: University of Pittsburgh ETD
    Creators/Authors:
    CreatorsEmailORCID
    JHA, ANUPMAanj14@pitt.edu
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairApodaca, Gerardgla6@pitt.edu
    Thesis AdvisorTraub, Lintontraub+@pitt.edu
    Committee MemberAridor, Meiraridor@pitt.edu
    Committee MemberHong, Yangyhong@pitt.edu
    Committee MemberLee, Tinathl@andrew.cmu.edu
    Title: CLATHRIN-MEDIATED ENDOCYTOSIS OF YOLK PROTEIN IN THE DROSOPHILA OOCYTE
    Status: Published
    Abstract: The developing egg chamber of Drosophila accumulates yolk protein to utilize during embryonic development. Egg chamber development is divided in 14 different stages, yolk protein endocytosis occurs between stages 8-11. Yolk protein is present in hemolymph, and the ovaries are bathed in hemolymph. Yolk protein forms a complex with Yolkless for endocytosis in oocyte. Yolkless is an LDL receptor superfamily member, and its cytosolic tail contains the signal for internalization by clathrin-mediated endocytosis. The Yolkless cytosolic tail harbors an typical FxNPxA sequence instead of the commonly found tyrosine-based sorting signal FxNPxY. The tyrosine-based sorting signals interact with PTB domain-containing proteins. In the present study, I show that PTB domaincontaining phagocytic protein Ced-6 is expressed in the cortical region of oocyte of the egg chamber. Ced-6 harbors all the biochemical properties of clathrin-associated sorting proteins. Ced-6 can physically interact with clathrin, AP-2 and phosphoinositide(4,5)P2. The Ced-6 PTB domain interacts with the cytosolic tail of Yolkless and clusters Yolkless into clathrin-coated pit. This clustering leads to internalization of Yolkless by clathrinmediated endocytosis. In conjunction with the FxNPxA signal, Yolkless cytosolic tail contains a functional, although atypical, dileucine signal. This atypical dileucine signal can physically interact with AP-2. This interaction leads to the clathrin-mediated endocytosis of Yolkless. Clathrin adaptor AP-2 and Ced-6 function redundantly in yolk protein uptake, as Ced-6-null flies accumulate yolk protein. Results from this study led to a model where both AP-2 and Ced-6 interact with Yolkless independently to ensure its internalization. Interaction of Ced-6 with clathrin and AP-2 leads to effective clustering of Yolkless for internalization by clathrin-mediated endocytosis.
    Date: 2011
    Date Type: Publication
    Defense Date: 08 December 2011
    Approval Date: 20 December 2011
    Submission Date: 18 December 2011
    Release Date: 20 December 2011
    Access Restriction: No restriction; The work is available for access worldwide immediately.
    Patent pending: No
    Number of Pages: 163
    Institution: University of Pittsburgh
    Thesis Type: Doctoral Dissertation
    Refereed: Yes
    Degree: PhD - Doctor of Philosophy
    Uncontrolled Keywords: Drosophila, Endocytosis, Oocyte, clathrin, Yolkless, Ced-6, AP-2
    Schools and Programs: School of Medicine > Cell Biology and Molecular Physiology
    Date Deposited: 20 Dec 2011 08:01
    Last Modified: 16 Jun 2014 17:47

    Actions (login required)

    View Item

    Document Downloads