Viral regulation of aquaporin 4, connexin 43, microcephalin and nucleolin

Abstract

The current study investigated whether human influenza viral infection in midpregnancy leads to alterations in proteins involved in brain development. Human influenza viral infection was administered to E9 pregnant Balb/c mice. Brains of control and virally-exposed littermates were subjected to microarray analysis, SDS-PAGE and western blotting at three postnatal stages. Microarray analysis of virally-exposed mouse brains showed significant, two-fold change in expression of multiple genes in both neocortex and cerebellum when compared to sham-infected controls. Levels of mRNA and protein levels of four selected genes were examined in brains of exposed mice. Nucleolin mRNA was significantly decreased in day 0 and day 35 neocortex and significantly increased in day 35 cerebellum. Protein levels were significantly upregulated at days 35 and 56 in neocortex and at day 56 in cerebellum. Connexin 43 protein levels were significantly decreased at day 56 in neocortex. Aquaporin 4 mRNA was significantly decreased in day 0 neocortex. Aquaporin 4 protein levels decreased in neocortex significantly at day 35. Finally, microcephalin mRNA was significantly decreased in day 56 neocortex and protein levels were significantly decreased at 56 cerebellum. These data suggest that influenza viral infection in midpregnancy in mice leads to long-term changes in brain markers for enhanced ribosome genesis (nucleolin), increased production of immature neurons (microcephalin), and abnormal glial-neuronal communication and neuron migration (connexin 43 and aquaporin 4).

Figure 1

Effects of prenatal human influenza viral infection on expression of aquaporin 4 protein levels in neocortex (A, B) and cerebella (C, D) of mouse progeny on postnatal days 35 (A, C) and 56 (B, D).

Figure 2

Effects of prenatal human influenza viral infection on expression of nucleolin protein levels in neocortex (A, B) and cerebella (C, D) of mouse progeny on postnatal days 35 (A, C) and 56 (B, D).

Figure 3

Effects of prenatal human influenza viral infection on expression of connexin 43 protein levels in neocortex (A, B) and cerebella (C, D) of mouse progeny on postnatal days 35 (A, C) and 56 (B, D).

Figure 4

Effects of prenatal human influenza viral infection on expression of microcephalin protein levels in neocortex (A, B) and cerebella (C, D) of mouse progeny on postnatal days 35 (A, C) and 56 (B, D).

Figure 5

Effects of prenatal human influenza viral infection on expression of β-actin protein levels in neocortex (A, B) and cerebella (C, D) of mouse progeny on postnatal days 35 (A, C) and 56 (B, D).

Figure 6

Prenatal viral infection on day 9 of pregnancy causes abnormal brain structure and function in adult Balb/c mice including: 1) apoptotic change in exposed mice as seen by increased pyramidal cell atrophy and increased neuronal density (Fatemi et al. 2002a); 2) migrational abnormalities as seen by increased GFAP, decreased Reelin early thinning and enlargement of brain; and 3) abnormal cell (neurons and astrocytes) proliferation as seen by decreased microcephalin and connexin 43 expression and by increased nucleolin and GFAP expression. Please note that postnatal dates denote significant changes in levels of various mRNAs or proteins.