Effects of Polyphosphate on Leukocyte Function

Structural characterization of Russula griseocarnosa polysaccharide and its improvement on hematopoietic function

The hematopoietic function of a polysaccharide derived from Russula griseocarnosa was demonstrated in K562 cells, and subsequently purified through chromatography to obtain RGP1. RGP1 is a galactan composed of 1,6-α-D-Galp as the main chain, with partial substitutions. A -CH3 substitution was detected at O-3 of 1,6-α-D-Galp. The possible branches at O-2 of 1,6-α-D-Galp was α-L-Fucp. In mice with cyclophosphamide (CTX)-induced hematopoietic dysfunction, RGP1 alleviated bone marrow damage and multinucleated giant cell infiltration of the spleen, increased the number of long-term hematopoietic stem cells, and regulated the levels of myeloid cells in the peripheral blood. Furthermore, RGP1 promoted the differentiation of activated T cells and CD4+ T cells without affecting natural killer cells and B cells. Proteomic analysis, detection of cytokines, and western blotting revealed that RGP1 could alleviate hematopoietic dysfunction by promoting the activation of CD4+ T cells and the Janus kinase/ signal transducer and activator of transcription 3 pathway. The present study provides experimental evidence to support the application of RGP1 in CTX-induced hematopoietic dysfunction.

Inorganic polyphosphate regulates functions of thymocytes via activation of P2X purinoreceptors

Inorganic polyphosphate (polyP) is an ancient polymer, which was proven to be a signalling molecule in the mammalian brain, mediating the communication between astrocytes via activation of P2Y1 purinoreceptors and modulating the activity of neurons. There is very limited information regarding the ability of polyP to transmit the information as an agonist of purinoreceptors in other cells and tissues. Here, we show that application of polyP to the suspension of primary thymocytes increases the concentration of intracellular calcium. PolyP evoked calcium signal was dependent on the presence of P2X inhibitors but not P2Y1 inhibitor. PolyP dependent increase in intracellular calcium concentration caused mild mitochondrial depolarization, which was dependent on inhibitors of purinoreceptors, extracellular calcium and inhibitor of mitochondrial calcium uniporter but wasn't dependent on cyclosporin A. Application of polyP modulated cell volume regulation machinery of thymocytes in calcium dependent manner. Molecular docking experiments revealed that polyP can potentially bind to several types of P2X receptors with binding energy similar to ATP - natural agonist of P2X purinoreceptors. Further molecular dynamics simulations with P2X4 showed that binding of one molecule of polyP dramatically increases permeability of this receptor-channel for water molecules. Thus, in this research we for the first time showed that polyP can interact with P2X receptors in thymocytes and modulate physiological processes.

Bioinformatics analysis of the genes associated with co-occurrence of heart failure and lung cancer

Deaths of non-cardiac causes in patients with heart failure (HF) are on the rise, including lung cancer (LC). However, the common mechanisms behind the two diseases need to be further explored. This study aimed to improve understanding on the co-occurrence of LC and HF. In this study, gene expression profiles of HF (GSE57338) and LC (GSE151101) were comprehensively analyzed using the Gene Expression Omnibus database. Functional annotation, protein-protein interaction network, hub gene identification, and co-expression analysis were proceeded when the co-differentially expressed genes in HF and LC were identified. Among 44 common differentially expressed genes, 17 hub genes were identified to be associated with the co-occurrence of LC and HF; the hub genes were verified in 2 other data sets. Nine genes, including ALOX5, FPR1, ADAMTS15, ALOX5AP, ANPEP, SULF1, C1orf162, VSIG4, and LYVE1 were selected after screening. Functional analysis was performed with particular emphasis on extracellular matrix organization and regulation of leukocyte activation. Our findings suggest that disorders of the immune system could cause the co-occurrence of HF and LC. They also suggest that abnormal activation of extracellular matrix organization, inflammatory response, and other immune signaling pathways are essential in disorders of the immune system. The validated genes provide new perspectives on the common underlying pathophysiology of HF and LC, and may aid further investigation in this field.