TY - JOUR
T1 - Alternative splicing of UCP1 by non-cell-autonomous action of PEMT
AU - Johnson, Jordan M.
AU - Verkerke, Anthony R.P.
AU - Maschek, J. Alan
AU - Ferrara, Patrick J.
AU - Lin, Chien Te
AU - Kew, Kimberly A.
AU - Neufer, P. Darrell
AU - Lodhi, Irfan J.
AU - Cox, James E.
AU - Funai, Katsuhiko
N1 - Funding Information:
We thank Dr. Dennis Vance from the University of Alberta and Dr. Karyn Esser from the University of Florida for donating the PEMTKO mice and HSA-MerCreMer mice, respectively. We also thank Dr. Kai Ge from the NIDDK for donating the SV40T brown preadipocytes for this study. We thank Diana L. Lim for her assistance with the figures. This project was funded by NIH grants DK095774 , DK107397 , DK109888 , and AG063077 to K·F., DK115867 and DK118333 to I.J.L., DK110656 to P.D.N., American Heart Association Predoctoral fellowships 19PRE34380991 to J.M.J. and 18PRE33960491 to A.R.P·V, and the Larry H. & Gail Miller Family Foundation to P.J.F. The University of Utah Metabolomics Core Facility is supported by S10 OD016232 , S10 OD021505 , and U54 DK110858 . Appendix A
Funding Information:
We thank Dr. Dennis Vance from the University of Alberta and Dr. Karyn Esser from the University of Florida for donating the PEMTKO mice and HSA-MerCreMer mice, respectively. We also thank Dr. Kai Ge from the NIDDK for donating the SV40T brown preadipocytes for this study. We thank Diana L. Lim for her assistance with the figures. This project was funded by NIH grants DK095774, DK107397, DK109888, and AG063077 to K?F. DK115867 and DK118333 to I.J.L. DK110656 to P.D.N. American Heart Association Predoctoral fellowships 19PRE34380991 to J.M.J. and 18PRE33960491 to A.R.P?V, and the Larry H. & Gail Miller Family Foundation to P.J.F. The University of Utah Metabolomics Core Facility is supported by S10 OD016232, S10 OD021505, and U54 DK110858.
Publisher Copyright:
© 2019 The Authors
PY - 2020/1
Y1 - 2020/1
N2 - Objective: Phosphatidylethanolamine methyltransferase (PEMT) generates phosphatidylcholine (PC), the most abundant phospholipid in the mitochondria and an important acyl chain donor for cardiolipin (CL) biosynthesis. Mice lacking PEMT (PEMTKO) are cold-intolerant when fed a high-fat diet (HFD) due to unclear mechanisms. The purpose of this study was to determine whether PEMT-derived phospholipids are important for the function of uncoupling protein 1 (UCP1) and thus for maintenance of core temperature. Methods: To test whether PEMT-derived phospholipids are important for UCP1 function, we examined cold-tolerance and brown adipose (BAT) mitochondria from PEMTKO mice with or without HFD feeding. We complemented these studies with experiments on mice lacking functional CL due to tafazzin knockdown (TAZKD). We generated several conditional mouse models to study the tissue-specific roles of PEMT, including mice with BAT-specific knockout of PEMT (PEMT-BKO). Results: Chow- and HFD-fed PEMTKO mice completely lacked UCP1 protein in BAT, despite a lack of difference in mRNA levels, and the mice were accordingly cold-intolerant. While HFD-fed PEMTKO mice exhibited reduced mitochondrial CL content, this was not observed in chow-fed PEMTKO mice or TAZKD mice, indicating that the lack of UCP1 was not attributable to CL deficiency. Surprisingly, the PEMT-BKO mice exhibited normal UCP1 protein levels. Knockout of PEMT in the adipose tissue (PEMT-AKO), liver (PEMT-LKO), or skeletal muscle (PEMT-MKO) also did not affect UCP1 protein levels, suggesting that lack of PEMT in other non-UCP1-expressing cells communicates to BAT to suppress UCP1. Instead, we identified an untranslated UCP1 splice variant that was triggered during the perinatal period in the PEMTKO mice. Conclusions: PEMT is required for UCP1 splicing that yields functional protein. This effect is derived by PEMT in nonadipocytes that communicates to BAT during embryonic development. Future research will focus on identifying the non-cell-autonomous PEMT-dependent mechanism of UCP1 splicing.
AB - Objective: Phosphatidylethanolamine methyltransferase (PEMT) generates phosphatidylcholine (PC), the most abundant phospholipid in the mitochondria and an important acyl chain donor for cardiolipin (CL) biosynthesis. Mice lacking PEMT (PEMTKO) are cold-intolerant when fed a high-fat diet (HFD) due to unclear mechanisms. The purpose of this study was to determine whether PEMT-derived phospholipids are important for the function of uncoupling protein 1 (UCP1) and thus for maintenance of core temperature. Methods: To test whether PEMT-derived phospholipids are important for UCP1 function, we examined cold-tolerance and brown adipose (BAT) mitochondria from PEMTKO mice with or without HFD feeding. We complemented these studies with experiments on mice lacking functional CL due to tafazzin knockdown (TAZKD). We generated several conditional mouse models to study the tissue-specific roles of PEMT, including mice with BAT-specific knockout of PEMT (PEMT-BKO). Results: Chow- and HFD-fed PEMTKO mice completely lacked UCP1 protein in BAT, despite a lack of difference in mRNA levels, and the mice were accordingly cold-intolerant. While HFD-fed PEMTKO mice exhibited reduced mitochondrial CL content, this was not observed in chow-fed PEMTKO mice or TAZKD mice, indicating that the lack of UCP1 was not attributable to CL deficiency. Surprisingly, the PEMT-BKO mice exhibited normal UCP1 protein levels. Knockout of PEMT in the adipose tissue (PEMT-AKO), liver (PEMT-LKO), or skeletal muscle (PEMT-MKO) also did not affect UCP1 protein levels, suggesting that lack of PEMT in other non-UCP1-expressing cells communicates to BAT to suppress UCP1. Instead, we identified an untranslated UCP1 splice variant that was triggered during the perinatal period in the PEMTKO mice. Conclusions: PEMT is required for UCP1 splicing that yields functional protein. This effect is derived by PEMT in nonadipocytes that communicates to BAT during embryonic development. Future research will focus on identifying the non-cell-autonomous PEMT-dependent mechanism of UCP1 splicing.
KW - Alternative splicing
KW - Brown adipose tissue
KW - Cardiolipin
KW - PEMT
KW - Phosphatidylcholine
KW - UCP1
UR - http://www.scopus.com/inward/record.url?scp=85075358327&partnerID=8YFLogxK
U2 - 10.1016/j.molmet.2019.10.007
DO - 10.1016/j.molmet.2019.10.007
M3 - Article
C2 - 31918922
AN - SCOPUS:85075358327
SN - 2212-8778
VL - 31
SP - 55
EP - 66
JO - Molecular Metabolism
JF - Molecular Metabolism
ER -