title: Sphingomyelin synthase 2, but not sphingomyelin synthase 1, is involved in HIV-1 envelope-mediated membrane fusion.
abstract: Membrane fusion between the viral envelope and plasma membranes of target cells has previously been correlated with HIV-1 infection. Lipids in the plasma membrane, including sphingomyelin, may be crucially involved in HIV-1 infection; however, the role of lipid-metabolic enzymes in membrane fusion remains unclear. In this study, we examined the roles of sphingomyelin synthase (SMS) in HIV-1 Env-mediated membrane fusion using a cell-cell fusion assay with HIV-1 mimetics and their target cells. We employed reconstituted cells as target cells that stably express Sms1 or Sms2 in Sms-deficient cells. Fusion susceptibility was ∼5-fold higher in Sms2-expressing cells (not in Sms1-expressing cells) than in Sms-deficient cells. The enhancement of fusion susceptibility observed in Sms2-expressing cells was reversed and reduced by Sms2 knockdown. We also found that catalytically nonactive Sms2 promoted membrane fusion susceptibility. Moreover, SMS2 co-localized and was constitutively associated with the HIV receptor·co-receptor complex in the plasma membrane. In addition, HIV-1 Env treatment resulted in a transient increase in nonreceptor tyrosine kinase (Pyk2) phosphorylation in Sms2-expressing and catalytically nonactive Sms2-expressing cells. We observed that F-actin polymerization in the region of membrane fusion was more prominent in Sms2-expressing cells than Sms-deficient cells. Taken together, our research provides insight into a novel function of SMS2 which is the regulation of HIV-1 Env-mediated membrane fusion via actin rearrangement.
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Hayashi
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nemoto-Sasaki
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanikawa
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605.
authors.forename: Saori
authors.initials: S
authors.lastname: Oka
authors.affiliation: AIDS Clinical Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655.
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Tsuchiya
authors.affiliation: Departments of Biomembrane and Biofunctional Chemistry, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, and.
authors.forename: Kouta
authors.initials: K
authors.lastname: Zama
authors.affiliation: Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, Honjo-machi 1, Saga 840-8502, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Mitsutake
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sugiura
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605,. Electronic address: ayamashi@pharm.teikyo-u.ac.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamashita
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology / Q000821:virology; D004789:Enzyme Activation; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D015870:Gene Expression; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D008565:Membrane Proteins / Q000502:physiology*; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000502:physiology*; D055503:Protein Multimerization; D021381:Protein Transport; D015728:Receptors, HIV / Q000378:metabolism; D017855:Transferases (Other Substituted Phosphate Groups) / Q000502:physiology*; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: D000199:Actins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D015728:Receptors, HIV; D051418:Focal Adhesion Kinase 2; C455440:SGMS1 protein, human; D017855:Transferases (Other Substituted Phosphate Groups)
keywords: Cell-Cell Fusion Assay; Human Immunodeficiency Virus (HIV); Membrane Fusion; Membrane Lipid; Phospholipid; Sphingolipid; Sphingomyelin Synthase