A role for the immune system-released activating agent (ISRAA) in the ontogenetic development of brain astrocytes.

Aminah M I Al-Awadi,Abdulaziz Isa Aljawder,Safa Taha,Moiz Bakhiet,Alyaa Mousa,Abdul Qadir Syed

doi:10.1371/journal.pone.0248455

Aminah M I Al-Awadi, Abdulaziz Isa Aljawder + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0248455

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Journal: PloS one	Publication Date: May 10, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Kuwait University, Arabian Gulf University

Abstract

The Immune System-Released Activating Agent (ISRAA) was discovered as a novel molecule that functions as a mediator between the nervous and immune systems in response to a nervous stimulus following an immune challenge. This research investigated the role of ISRAA) in promoting the ontogeny of the mouse brain astrocytes. Astrocyte cultures were prepared from two-month-old BALB/c mice. Recombinant ISRAA protein was used to stimulate astrocyte cultures. Immunohistochemistry and ELISA were utilized to measure ISRAA and IFN-γ levels, IFN-γR expression and STAT1 nuclear translocation. MTT-assay was used to evaluate cellular survival and proliferation. To assess astrocyte cell lysates and tyrosine-phosphorylated proteins, SDS-PAGE and western blot were used. ISRAA was highly expressed in mouse embryonic astrocytes, depending on cell age. Astrocytes aged seven days (E7) showed increased proliferation and diminished differentiation, while 21-day-old (E21) astrocytes depicted reversed effects. IFN-γ was involved in the ISRAA action as ISRAA induced IFN-γ in both age groups, but only E21 astrocytes expressed IFN-γR. ISRAA stimulation of E21 resulted in tyrosine phosphorylation of numerous cellular proteins and the nuclear translocation of STAT1, a signalling pathway utilized by IFN-γ. The results suggest that ISRAA is involved in mouse brain development through the cytokine network involving IFN-γ.

Highlights

The novel immune modulator Immune System-Released Activating Agent (ISRAA) was recently discovered as a 125 amino acid protein of a 15kDa molecular mass
It is a protein secreted due to a central nervous system stimulus triggered by parasitic challenge and has been found to modulate the immune system by acting on the spleen [1]
This work indicates the role ISRAA plays in mouse brain astrocytes development, through the cytokine network involving IFN-γ, as illustrated in the graphical abstract (Fig 1)

Summary

Introduction

The novel immune modulator Immune System-Released Activating Agent (ISRAA) was recently discovered as a 125 amino acid protein of a 15kDa molecular mass. Albumin; CNS, Central Nervous System; E21, Astrocytes aged twenty one days; E7, Astrocytes aged seven days; ELISA, Enzyme-Linked Immunosorbent Assay; FCS, Foetal Calf Serum; GFAP, Glial Fibrillary Acid Protein; GFP, Green Fluorescent Protein; ISRAA, Immune SystemReleased Activating Agent; MHC, Major Histocompatibility Complex; NIH, National Institute of Health; NPCs, Neural Progenitor Cells; PBS, Phosphate-Buffered Saline; RPM, Rounds Per Minute; RT, Room Temperature. ISRAA has been shown to downregulate T-cell activation and the phosphorylation of tyrosine Y416 in the Src-family kinases. Down regulation of T-cell activation and cytokine production has been noted in the splenocytes of ISRAA knockout (-/-) mice, which show lymphoid organ hyperplasia. The transcription factor ELF1, which is involved in T cell regulation, is a binding partner for ISRAA, and a transcriptomic study using the ISRAAoverexpressing cell line EL4 has demonstrated the differential expression of numerous genes required for T-cell activation and growth [5]

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