A Comparative Analysis of Erythropoietin and Carbamoylated Erythropoietin Proteome Profiles.

Neeraj K. Tiwari,Vikas Kumar,Samuel S. Newton,Monica Sathyanesan

doi:10.3390/life11040359

Abstract

In recent years, erythropoietin (EPO) has emerged as a useful neuroprotective and neurotrophic molecule that produces antidepressant and cognitive-enhancing effects in psychiatric disorders. However, EPO robustly induces erythropoiesis and elevates red blood cell counts. Chronic administration is therefore likely to increase blood viscosity and produce adverse effects in non-anemic populations. Carbamoylated erythropoietin (CEPO), a chemically engineered modification of EPO, is non-erythropoietic but retains the neurotrophic and neurotrophic activity of EPO. Blood profile analysis after EPO and CEPO administration showed that CEPO has no effect on red blood cell or platelet counts. We conducted an unbiased, quantitative, mass spectrometry-based proteomics study to comparatively investigate EPO and CEPO-induced protein profiles in neuronal phenotype PC12 cells. Bioinformatics enrichment analysis of the protein expression profiles revealed the upregulation of protein functions related to memory formation such as synaptic plasticity, long term potentiation (LTP), neurotransmitter transport, synaptic vesicle priming, and dendritic spine development. The regulated proteins, with roles in LTP and synaptic plasticity, include calcium/calmodulin-dependent protein kinase type 1 (Camk1), Synaptosomal-Associated Protein, 25 kDa (SNAP-25), Sectretogranin-1 (Chgb), Cortactin (Cttn), Elongation initiation factor 3a (Eif3a) and 60S acidic ribosomal protein P2 (Rplp2). We examined the expression of a subset of regulated proteins, Cortactin, Grb2 and Pleiotrophin, by immunofluorescence analysis in the rat brain. Grb2 was increased in the dentate gyrus by EPO and CEPO. Cortactin was induced by CEPO in the molecular layer, and pleiotrophin was increased in the vasculature by EPO. The results of our study shed light on potential mechanisms whereby EPO and CEPO produce cognitive-enhancing effects in clinical and preclinical studies.

Highlights

Erythropoietin (EPO) is a 165 amino acid glycoprotein with well-known roles in red blood cell production in the body
Several hematological parameters were measured after EPO and Carbamoylated erythropoietin (CEPO) administration (Table 1)
EPO strongly elevated several of the measured values, while CEPO was comparable to control values

Summary

Introduction

Erythropoietin (EPO) is a 165 amino acid glycoprotein with well-known roles in red blood cell production in the body. The levels of EPO have been shown to increase in the brain, where it functions as a neuroprotectant [1]. Due to its neurotrophic and neuroprotective effects, EPO has been extensively tested in both preclinical and clinical CNS studies. EPO in a double-blind, randomized clinical trial reported improvements in depression scores and cognition [2]. EPO clinical trials conducted in combination with brain imaging reported a positive correlation between memory improvement and reversal of brain matter loss in specific hippocampal subregions of depressed patients [3]. These studies indicate that EPO has antidepressant and cognitive-enhancing effects

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Results