The Anderson Lab research focuses on the post-transcriptional mechanisms that regulate the production of inflammatory mediators. Many mRNAs that encode inflammatory mediators (e.g. TNF-alpha, IL-1-beta, COX-2, matrix metalloproteinase) possess adenine and uridine-rich elements (AREs) in their 3’ untranslated regions that inhibit translation and promote mRNA decay. The regulated activity of ARE-binding proteins (ARE-BPs) is required to overcome constitutive translational repression and mRNA instability.
TIA-1, TIAR and TTP are ARE-BPs that prevent the pathological overexpression of inflammatory mediators. TIA-1 and TIAR inhibit the translation of TNFa, COX-2 and MMP-13 transcripts, whereas TTP promotes the degradation of TNFa and COX-2 transcripts. Because of this, TIA-1 and TTP function as arthritis suppressor genes: TIA-1-/- mice develop mild arthritis, TTP-/- mice develop severe arthritis and TIA-1/TTP-/- female mice develop very severe spontaneous arthritis. Whereas macrophages are a major source of arthritogenic cytokine in mice lacking TIA-1 or TTP, neutrophils are a major source of arthritogenic cytokine in mice lacking both TIA-1 and TTP. Thus, TIA-1 and TTP are genetic modifiers of inflammatory arthritis that can alter the spectrum of cells that produce arthritigenic cytokine.
TIA-1 and TTP also regulate the general translational arrest observed in cells subjected to environmental stress. Both TIA-1 and TTP regulate the assembly of cytoplasmic stress granules, discrete foci at which untranslated mRNAs accumulate in stressed cells. Stress-induced phosphorylation of the translation initiation factor eIF2-alpha allows TIA-1 to promote the assembly of untranslated, non-canonical 48S preinitiation complexes that are the core constituents of stress granules. The lab research has proposed that stress granules function as sites of mRNA triage: by monitoring the composition and function of mRNP complexes, the stress granule determines whether individual mRNAs are stored, degraded, or re-initiated.