A conserved polybasic domain mediates plasma membrane targeting of Lgl and its regulation by hypoxia.
Lethal giant larvae (Lgl) plays essential and conserved functions in regulating both cell polarity and tumorigenesis in Drosophila melanogaster and vertebrates. It is well recognized that plasma membrane (PM) or cell cortex localization is crucial for Lgl function in vivo, but its membrane-targeting mechanisms remain poorly understood. Here, we discovered that hypoxia acutely and reversibly inhibits Lgl PM targeting through a posttranslational mechanism that is independent of the well-characterized atypical protein kinase C (aPKC) or Aurora kinase-mediated phosphorylations. Instead, we identified an evolutionarily conserved polybasic (PB) domain that targets Lgl to the PM via electrostatic binding to membrane phosphatidylinositol phosphates. Such PB domain-mediated PM targeting is inhibited by hypoxia, which reduces inositol phospholipid levels on the PM through adenosine triphosphate depletion. Moreover, Lgl PB domain contains all the identified phosphorylation sites of aPKC and Aurora kinases, providing a molecular mechanism by which phosphorylations neutralize the positive charges on the PB domain to inhibit Lgl PM targeting.
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Wei
W
Dong
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Xuejing
X
Zhang
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Weijie
W
Liu
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Yi-jiun
YJ
Chen
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261 Nanjing Medical University, Nanjing 210029, China.
Juan
J
Huang
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Erin
E
Austin
Department of Pharmacology & Chemical Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Alicia M
AM
Celotto
Department of Pharmacology & Chemical Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Wendy Z
WZ
Jiang
Department of Pharmacology & Chemical Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Michael J
MJ
Palladino
Department of Pharmacology & Chemical Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Yu
Y
Jiang
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261.
Gerald R V
GR
Hammond
Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261 yhong@pitt.edu.
Yang
Y
Hong
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D064127:Aurora Kinases / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000235:genetics*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D055672:Static Electricity; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
D029721:Drosophila Proteins; D018129:Phosphatidylinositol Phosphates; D025521:Tumor Suppressor Proteins; C081435:l(2)gl protein, Drosophila; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D064127:Aurora Kinases; C115015:PKC-3 protein; D011493:Protein Kinase C