Iron deficiency in Astrocytes alter cellular status and impact on oligodendrocyte differentiation

M. SILVINA MARCORA; PILAR GONI; JORGE CORREALE; JUANA MARIA PASQUINI

Congreso; FIRST MEETING GLIA CLUB SOUTHERN CONE; 2022

Iron deficiency has been shown to affect CNS development and induce hypomyelination. Oligodendrocytes (OLG) are the primary myelinating cells in the CNS and the mayor iron-containing cell whereas astrocytes (AST) accumulate iron but at lower levels. Astrocytes have shown to promote myelination by releasing soluble factors as well as via cell contact with OLG. Previous work from our laboratory showed that in a gestational iron deficiency model, not only OLG but also AST maturation was altered (Rosato-Siri et al. 2018).In the present study, we generate an in vitro model of iron deficiency by silencing the Divalent Metal Transporter 1 (DMT1) in AST. DMT1 participates in the intracellular export of iron from endosomal compartments. Primary astrocyte cultures were transfected with siRNA for DMT1 (siDMT1), and several parameters were analyzed. These iron deficient astrocytes showed no changes in the proliferation status (BrdU and KI67) and displayed an immature profile as indicated by the reduced expression of AQP4. To analyze the impact of iron deficiency AST on OLG maturation, AST conditioned medium (ACM) was added to oligodendrocyte precursors cells (OPC) cultures. Immunocytochemistry analyses showed an increment in OLG immaturity markers (NG2 and PDGFr) and a decrement in OLG maturity markers, (O4 and MBP) in siDMT1 AST, indicating a reduction in the differentiation process. These correlates with a decrement in the expression of secreted factors such as LIF, NRG1 and IGF-1, known to promote differentiation in OLG. Iron deficiency has been shown to alter mitochondrial functioning. Immunofluorescence analyzes showed that siDMT1 AST displayed increased number and reduced size of mitochondria compared to control cells. Moreover, q-PCR assays showed that the expression of genes related to mitochondrial fission and fusion was altered, favoring an increment in the fission process. Our results showed that iron deficient AST displayed cellular alterations, such as disruption in mitochondrial dynamics, that compromise OLG maturation