title: Modulation of PICALM Levels Perturbs Cellular Cholesterol Homeostasis.
abstract: PICALM (Phosphatidyl Inositol Clathrin Assembly Lymphoid Myeloid protein) is a ubiquitously expressed protein that plays a role in clathrin-mediated endocytosis. PICALM also affects the internalization and trafficking of SNAREs and modulates macroautophagy. Chromosomal translocations that result in the fusion of PICALM to heterologous proteins cause leukemias, and genome-wide association studies have linked PICALM Single Nucleotide Polymorphisms (SNPs) to Alzheimer's disease. To obtain insight into the biological role of PICALM, we performed gene expression studies of PICALM-deficient and PICALM-expressing cells. Pathway analysis demonstrated that PICALM expression influences the expression of genes that encode proteins involved in cholesterol biosynthesis and lipoprotein uptake. Gas Chromatography-Mass Spectrometry (GC-MS) studies indicated that loss of PICALM increases cellular cholesterol pool size. Isotopic labeling studies revealed that loss of PICALM alters increased net scavenging of cholesterol. Flow cytometry analyses confirmed that internalization of the LDL receptor is enhanced in PICALM-deficient cells as a result of higher levels of LDLR expression. These findings suggest that PICALM is required for cellular cholesterol homeostasis and point to a novel mechanism by which PICALM alterations may contribute to disease.
authors.affiliation: Department of Pharmacology & Cancer Biology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Mercer
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Argus
authors.affiliation: Department of Pediatrics, Division of Pediatric Hematology-Oncology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Donna M
authors.initials: DM
authors.lastname: Crabtree
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America; Center for Genomic and Computational Biology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Keenan
authors.affiliation: Department of Radiology, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
authors.forename: Moses Q
authors.initials: MQ
authors.lastname: Wilks
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, United States of America; Center for Genomic and Computational Biology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Jen-Tsan Ashley
authors.initials: JT
authors.lastname: Chi
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Bensinger
authors.affiliation: Department of Pediatrics, Division of Pediatric Hematology-Oncology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Catherine P
authors.initials: CP
authors.lastname: Lavau
authors.affiliation: Department of Pharmacology & Cancer Biology, Duke University, Durham, North Carolina, United States of America; Department of Pediatrics, Division of Pediatric Hematology-Oncology, Duke University, Durham, North Carolina, United States of America.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Wechsler
mesh_terms: D000818:Animals; D053898:Biosynthetic Pathways / Q000235:genetics; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D015870:Gene Expression; D055786:Gene Knockout Techniques; D006706:Homeostasis; D006801:Humans; D051379:Mice; D034041:Monomeric Clathrin Assembly Proteins / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity; D021381:Protein Transport; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011973:Receptors, LDL / Q000378:metabolism
chemical_list: D034041:Monomeric Clathrin Assembly Proteins; C439003:PICALM protein, human; C573094:PICALM protein, mouse; D034741:RNA, Small Interfering; D011973:Receptors, LDL; D002784:Cholesterol