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Phospholipase C-related catalytically inactive protein (PRIP) regulates lipolysis in adipose tissue by modulating the phosphorylation of hormone-sensitive lipase.

PLoS ONE. 2014 Jun 19;9(6):e100559. eCollection 2014
Toshiya Okumura 1 , Kae Harada 2 , Kana Oue 3 , Jun Zhang 2 , Satoshi Asano 2 , Masaki Hayashiuchi 2 , Akiko Mizokami 4 , Hiroto Tanaka 5 , Masahiro Irifune 6 , Nobuyuki Kamata 7 , Masato Hirata 4 , Takashi Kanematsu 2
Toshiya Okumura 1 , Kae Harada 2 , Kana Oue 3 , Jun Zhang 2 , Satoshi Asano 2 , Masaki Hayashiuchi 2 , Akiko Mizokami 4 , Hiroto Tanaka 5 , Masahiro Irifune 6 , Nobuyuki Kamata 7 , Masato Hirata 4 , Takashi Kanematsu 2
+ et al

[No authors listed]

Author information
  • 1 Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Department of Oral Surgery, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
  • 2 Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
  • 3 Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Department of Dental Anesthesiology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
  • 4 Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
  • 5 Department of Cellular and Molecular Pharmacology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
  • 6 Department of Dental Anesthesiology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
  • 7 Department of Oral Surgery, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
全文

摘要


Phosphorylation of hormone-sensitive lipase (HSL) and perilipin by protein kinase A promotes the hydrolysis of lipids in adipocytes. Although activation of lipolysis by has been well studied, inactivation via protein phosphatases is poorly understood. Here, we investigated whether phospholipase C-related catalytically inactive protein (PRIP), a binding partner for protein phosphatase 1 and protein phosphatase 2A (PP2A), is involved in lipolysis by regulating phosphatase activity. PRIP knockout (PRIP-KO) mice displayed reduced body-fat mass as compared with wild-type mice fed with standard chow ad libitum. Most other organs appeared normal, suggesting that mutant mice had aberrant fat metabolism in adipocytes. HSL in PRIP-KO adipose tissue was highly phosphorylated compared to that in wild-type mice. Starvation of wild-type mice or stimulation of adipose tissue explants with the catabolic hormone, adrenaline, translocated both PRIP and PP2A from the cytosol to lipid droplets, but the translocation of PP2A was significantly reduced in PRIP-KO adipocytes. Consistently, the phosphatase activity associated with lipid droplet fraction in PRIP-KO adipocytes was significantly reduced and was independent of adrenaline stimulation. Lipolysis activity, as assessed by measurement of non-esterified fatty acids and glycerol, was higher in PRIP-KO adipocytes. When wild-type adipocytes were treated with a phosphatase inhibitor, they showed a high lipolysis activity at the similar level to PRIP-KO adipocytes. Collectively, these results suggest that PRIP promotes the translocation of phosphatases to lipid droplets to trigger the dephosphorylation of HSL and perilipin A, thus reducing lipolysis.