Enrichment of microsomes from Chinese hamster ovary cells by subcellular fractionation for its use in proteomic analysis

PLoS One. 2020 Aug 25;15(8):e0237930. doi: 10.1371/journal.pone.0237930. eCollection 2020.

Abstract

Chinese hamster ovary cells have been the workhorse for the production of recombinant proteins in mammalian cells. Since biochemical, cellular and omics studies are usually affected by the lack of suitable fractionation procedures to isolate compartments from these cells, differential and isopycnic centrifugation based techniques were characterized and developed specially for them. Enriched fractions in intact nuclei, mitochondria, peroxisomes, cis-Golgi, trans-Golgi and endoplasmic reticulum (ER) were obtained in differential centrifugation steps and subsequently separated in discontinuous sucrose gradients. Nuclei, mitochondria, cis-Golgi, peroxisomes and smooth ER fractions were obtained as defined bands in 30-60% gradients. Despite the low percentage represented by the microsomes of the total cell homogenate (1.7%), their separation in a novel sucrose gradient (10-60%) showed enough resolution and efficiency to quantitatively separate their components into enriched fractions in trans-Golgi, cis-Golgi and ER. The identity of these organelles belonging to the classical secretion pathway that came from 10-60% gradients was confirmed by proteomics. Data are available via ProteomeXchange with identifier PXD019778. Components from ER and plasma membrane were the most frequent contaminants in almost all obtained fractions. The improved sucrose gradient for microsomal samples proved being successful in obtaining enriched fractions of low abundance organelles, such as Golgi apparatus and ER components, for biochemical and molecular studies, and suitable for proteomic research, which makes it a useful tool for future studies of this and other mammalian cell lines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Cell Nucleus / metabolism
  • Cell Nucleus / ultrastructure
  • Centrifugation
  • Cricetinae
  • Cricetulus
  • Cytosol / metabolism
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum / ultrastructure
  • Gene Ontology
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / ultrastructure
  • Microsomes / metabolism*
  • Microsomes / ultrastructure
  • Mitochondria / ultrastructure
  • Proteome / metabolism
  • Proteomics*
  • Software
  • Subcellular Fractions / metabolism

Substances

  • Proteome

Grants and funding

Saumel Pérez-Rodriguez is a doctoral student from Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México (UNAM) and received fellowship number 396822 from CONACYT. This project was developed under the Institutional Program of the Instituto de Investigaciones Biomédicas-UNAM: “La producción de biomoléculas de interés biomédico en bacterias y hongos”. This work was supported by “Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica, Universidad Nacional Autónoma de México” (PAPIIT-UNAM IN210419: NAVC, IT-200719: MATR, IN-208415: NAVC). The work done at Novo Nordisk Foundation Center for Biosustainability, was founded by Novo Nordisk foundation (NNF10CC1016517: TW and BGV). GE Healthcare Life Sciences provided support in cell culture media and supplies, GeneTex provided the generous gift of antibodies, and Dr. Paola Toledo Ibelles from Inolab Especialistas en Servicio provided support in cell culture media. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.