The role of complemente componente C4 on human astrocyte functions

• Grant number: 22/16095-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2023
• End date: April 30, 2025
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Andréa Laurato Sertié
• Grantee: Isabella de Sousa Nóbrega
• Host Institution: Instituto Israelita de Ensino e Pesquisa Albert Einstein (IIEPAE). Sociedade Beneficente Israelita Brasileira Albert Einstein (SBIBAE). São Paulo , SP, Brazil

Abstract

The Complement System (CS) consists of a set of circulating and cell membrane proteins that play essential roles in the body's defense against pathogens and tissue injury. In addition, in recent years, several studies have shown that CS proteins also play important roles in brain development and plasticity, both under normal physiological circumstances and after an insult, such as inflammation. All major cell types in the brain (including neuroprogenitor cells, neurons, glial cells, and microglia) express at least some components of the CS, which contributes to processes such as neurogenesis, neuronal migration, synaptic pruning and brain remodeling. Furthermore, it was shown that CS knockout mice or mice that overexpress certain CS components (such as C1q, C3 and C4) may present behavioral abnormalities similar to those observed in individuals with Autism Spectrum Disorder (ASD). Recently, our research group have analyzed the expression of several CS components in different brain cell types derived from induced pluripotent stem cells (iPSCs) of individuals with ASD and neurotypical controls, and observed that complement C4 mRNA and protein are expressed in significantly lower levels by astrocytes derived from ASD individuals compared to control astrocytes. However, the functional consequences of decreased C4 expression and secretion by astrocytes are still unknown. This project aims to verify whether astrocytes differentiated from iPSCs edited to knockout copies of the C4A/B genes present alterations in differentiation, morphology, proliferation, secretion of cytokines and/or CS molecules. To this end, we will use as an experimental model iPSC-derived astrocytes from 2-3 control individuals, which will be edited by the CRISPR-Cas9 methodology to knockout copies of the C4A/B genes and thus decrease the expression of the C4 protein. These edited astrocytes, as well as wild-type isogenic lines, will be analyzed according to their morphology and ability to differentiate, proliferate, secrete cytokines and/or CS components.