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: Yasuhiro Hayashi, Yoko Nemoto-Sasaki, Takashi Tanikawa, Saori Oka, Kiyoto Tsuchiya, Kouta Zama, Susumu Mitsutake, Takayuki Sugiura, Atsushi Yamashita
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 289 Issue 44 Pg. 30842-30856 (Oct 31 2014) ISSN: 1083-351X [Electronic] United States
• PMID: 25231990 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Actins
• Membrane Proteins
• Nerve Tissue Proteins
• Receptors, HIV
• Focal Adhesion Kinase 2
• SGMS1 protein, human
• Transferases (Other Substituted Phosphate Groups)

Topics

• Actins (metabolism)
• Animals
• Cell Membrane (enzymology, virology)
• Enzyme Activation
• Focal Adhesion Kinase 2 (metabolism)
• Gene Expression
• HIV-1 (physiology)
• Humans
• Jurkat Cells
• Membrane Proteins (physiology)
• Mice, Knockout
• Nerve Tissue Proteins (physiology)
• Protein Multimerization
• Protein Transport
• Receptors, HIV (metabolism)
• Transferases (Other Substituted Phosphate Groups) (physiology)
• Virus Attachment
• Virus Internalization