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Published on: December 10, 2007

A distal effect of microsomal triglyceride transfer protein deficiency on the lysosomal recycling of CD1d

Yuval Sagiv1, Li Bai, Datsen G Wei

  • 1Committee on Immunology, University of Chicago, Chicago, IL 60637, USA.

The Journal of Experimental Medicine
|April 4, 2007
PubMed

Insights

Microsomal triglyceride transfer protein (MTP) deficiency impairs CD1d molecule recycling from lysosomes to the plasma membrane. This suggests MTP has a novel role in late-stage CD1d trafficking within the lysosomal compartment.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • Microsomal triglyceride transfer protein (MTP) is an ER-resident protein crucial for apolipoprotein B lipid loading.
  • MTP was previously hypothesized to directly regulate CD1d biosynthesis and lipid loading.
  • CD1d is an MHC I-like molecule essential for presenting lipid antigens.

Purpose of the Study:

  • To investigate the precise role of MTP in CD1d trafficking and function.
  • To determine if MTP's influence on CD1d occurs in the early secretory pathway or at later stages.

Main Methods:

  • Utilized MTP-deficient models.
  • Performed coprecipitation and lipid loading assays.
  • Assessed CD1d biosynthesis, glycosylation, internalization, and lysosomal recycling.
  • Conducted functional assays for CD1d-mediated lipid presentation.

Main Results:

  • MTP deficiency did not affect CD1d biosynthesis, glycosylation, or cell surface internalization.
  • A significant impairment was observed in the recycling of CD1d from the lysosome to the plasma membrane.
  • Functional defects in CD1d-mediated lipid presentation were localized to the lysosome.

Conclusions:

  • MTP's primary role in CD1d regulation occurs distal to the ER and Golgi.
  • MTP is essential for the late-stage lysosomal recycling of CD1d.
  • MTP plays a novel, unexpected role in lysosomal trafficking of CD1d.

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