Alternative splicing regulation and RNA polymerase II elongation mediated by light

MICAELA GODOY HERZ; MARÍA GUILLERMINA KUBACZKA; ALBERTO RODOLFO KORNBLIHTT

Rosario, Provincia de Santa Fé

Simposio; Simposio de Genómica Funcional de Plantas; 2017

IBR-CONICET

We have previously shown that light/dark conditions affect several alternative splicing events in A. thaliana, including that of the splicing factor RS31. Treatment of seedlings with trichostatin A, a drug that inhibits histone deacetylases, mimics the effect of light on RS31 alternative splicing (AS). This led us to investigate whether chromatin modifications play a role in the regulation of AS by light. However, chromatin immunoprecipitation assays showed no light-dependent changes in H3K9Ac or H3K9me2 along the RS31 gene. Knowing that the elongation rate of RNA polymerase II (RNAPII) modulates AS in mammalian cells (de la Mata et al, 2003) we asked whether a similar mechanism is involved in the light regulation of RS31 AS. First, we observed that treatment of seedlings with camptothecin, a drug that inhibits RNAPII elongation, mimics the effect of darkness on RS31 AS. Second, we found that mutant plants defective in the elongation factor TFIIS do not respond to light/dark conditions as wild type plants, mimicking the effect of darkness on AS. Finally, preliminary results aimed at detecting changes in RNAPII elongation through quantifications of pre-mRNA at proximal and distal regions of the RS31 support a scenario in which light controls RS31 AS by increasing RNAPII elongation.