Identification of Proteins in Lipofuscin Using Antibodies within the Human Protein Atlas

Evelina Sjöstedt¹, Dijana Djureinovic¹, Dijana Djureinovic², Caroline Kampf¹

¹Department of Immunology, Genetics and Pathology, Human Protein Atlas, Science for Life Laboratory, Uppsala University, Uppsala, Sweden, ²Department of Neuroscience, Human Protein Atlas, Science for Life Laboratory, Karolinska Institute, Stockholm, Sweden

Background

The Human Protein Atlas (HPA) is a research project that aims to visualize the cellular and subcellular location of every human protein by using monospecific polyclonal antibodies¹. This high-throughput approach enables the discovery of new protein distribution profiles and can also provide deeper insights into already known patterns. Here we used HPA antibodies to identify proteins associated with the age pigment lipofuscin.

Lipofuscin is mainly present in post mitotic cells. It consists of lipids, proteins, carbohydrates and a small amount of metals. Despite that lipofuscin has been well-known for a long time the exact composition of the protein portion is uncertain².

Conclusions

All methods; histochemical staining, confocal imaging and Western blot verified that the staining pattern observed by the antibodies was indeed lipofuscin.

The large collection of antibodies produced within the HPA project has proven to be a valuable tool to identify compartments of cellular complexes like lipofuscin.

A number of the previously unknown proteins within lipofuscin have been identified; GGH (HPA025226), MIP18 (HPA041736) and HDGL1 (HPA045679). Thereby a few pieces of the lipofuscin puzzle have been solved.

References

1. 2005. A Human Protein Atlas for Normal and Cancer Tissues Based on Antibody Proteomics. [Internet]. Molecular & Cellular Proteomics. Available from: https://www.mcponline.org/content/4/12/1920

2. Brunk UT, Terman A. 2002. Lipofuscin: mechanisms of age-related accumulation and influence on cell function12 1Guest Editor: Rajindar S. Sohal 2This article is part of a series of reviews on ?Oxidative Stress and Aging.? The full list of papers may be found on the homepage of the journal.. Free Radical Biology and Medicine. 33(5):611-619. https://doi.org/10.1016/s0891-5849(02)00959-0

The HPR project is funded by the Knut & Alice Wallenberg foundation. The atlas is part of the HUPO Human Antibody Initiative (HAI).