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Proteomic Identification of Novel LMF1 Partners: Defining the LPL Maturation Complex
Author(s) -
Neher Saskia,
BabiloniaRosa Melissa,
Broadwell Lindsey
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1132.11
Subject(s) - lipoprotein lipase , endoplasmic reticulum , secretion , lipase , chaperone (clinical) , protein disulfide isomerase , protein folding , microbiology and biotechnology , biochemistry , secretory protein , foldase , pancreatic lipase , chemistry , biology , enzyme , gene , medicine , pathology , escherichia coli , groel
Lipoprotein Lipase (LPL) is a secreted lipase responsible for clearing triglycerides from the blood. If LPL levels are insufficient, individuals suffer from severe hypertriglyceridemia. LPL requires a specialized chaperone, Lipase Maturation Factor 1 (LMF1), for proper folding and exit from the endoplasmic reticulum (ER). When LMF1 is absent, LPL forms disulfide‐bonded aggregates in the ER, resulting in a phenotype similar to LPL deficiency. We aimed to understand how LMF1 assists with LPL folding. To this end, we combined site‐specific incorporation of an unnatural, photocrosslinkable amino acid into LMF1 with proteomics to identify novel LMF1‐interacting proteins. We also found the known LMF1 interacting partner, SEL1L. For certain candidates including protein‐disulfide isomerases and chaperones we confirmed complex formation with LMF1. We further established the role of our candidate proteins in LPL folding and secretion using RNAi knockdowns in cultured cells. Reduction in levels of the novel LMF1 partners reduced LPL secretion. Secretion of the sequence‐related, but LMF1‐independent lipase Pancreatic Lipase (PL) was not affected. Thus, we have identified multiple novel LMF1‐binding partners that are necessary for proper LPL folding and secretion. Support or Funding Information This work was funded by grants from the NIH (1ROOHL098277) and the Pew Charitable Trusts to SBN and by a UNC dissertation completion fellowship to MAB.