Differential subnuclear localization of the MBD4L DNA glycosylase splicing isoforms. Possible role(s) on stress responses

NOTA F; TORRES J.R; CECCHINI N; ALVAREZ M.E; COBO S

Ciudad Autonoma de Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

DNA glycosylases are key enzymes for organisms? genome stabilitymediating DNA damage repair. Among them, MBD4L is a nuclearArabidopsis DNA glycosylase acting during stress conditions.Interestingly, MBD4L gene can generate two-isoforms through theretention of a protein-coding cryptic intron (exitron). It is believedthat exitron splicing events result in protein versions with alternativefunctional domains and/or post-translational modifications. Takingthis into account, we analyzed MBD4L splicing-isoforms transcriptlevels, subcelular localization and contribution to damaged DNA correction.We found that the MBD4L alternative transcripts changedtheir relative levels depending on the stress applied. Surprisingly,when expressed as GFP fusions each of the MBD4 isoforms locatedat different subnuclear compartments in both Arabidopsis andNicotiana benthamiana plants. Moreover, some stresses induceddynamic changes in enzyme subnuclear localization. On the otherhand, although showing distinctive localization the overexpressionof both MBD4L isoforms increased resistance to a DNA damagingagent. Altogether, our results indicate that MBD4L location can bedriven by exitron alternative splicing mechanisms. However, additionallevels of control may determine differential subcellular requirementsfor MBD4L isoforms under particular circumstances. A putativemodel for MBD4L nuclear role/localization will be presented.