CROSSTALK BETWEEN THE HISTONE ACETYLTRANSFERASE KAT6B AND THE PLURIPOTENCY TRANSCRIPTION FACTORS OCT4 AND NANOG IN EMBRYONIC STEM CELLS

COSENTINO, MARIA SOLEDAD; SOLARI, CLAUDIA; PETRONE, MARIA VICTORIA; SEVLEVER, GUSTAVO; GUBERMAN, ALEJANDRA; OSES, CAMILA; WAISMAN, ARIEL; FRANCIA, MARCOS; MIRIUKA, SANTIAGO; VAZQUEZ ECHEGARAY, CAMILA; ÁLVAREZ, YANINA; SCHULTZ, MARCELO; LEVI, VALERIA

Chascomús

Taller; IV Taller de Biología Celular y del Desarrollo; 2018

IIB-INTECH

The transition between transcriptional programs associated with Stem Cell (SC) differen=a=on is related to changes in chroma=n structure. Kat6b is a transcrip=onal coac=vator with histone acetyltransferase ac=vity important for the establishment and self-renewal of adult neural SC. Moreover, muta=ons in only one allele lead to intellectual disability in humans. It was reported that Kat6b gene possess a super-enhancer, a regulatory element highly occupied by Embryonic SC (ESC) key transcrip=on factors (TFs). However, the relevance of this chroma=n modifier in ESC remains to be established. The aim of this work was to study the role of Kat6b in the maintenance of ESC?s proper=es. We found that Kat6b is expressed in mouse ESC (mESC) and is repressed along differen=a=on. Moreover, ChIP-seq analysis and shRNA experiments suggest that Kat6b expression is regulated by pluripotency TFs Nanog and Oct4. To study Kat6b relevance, we generated a knock-out (KO) mESC line by CRISPR/Cas9. Kat6b-/- cell colonies were flaien and less refringent than wild type (WT), however they did not display significant differences regarding the expression of early differen=a=on and pluripotency markers. Moreover, KO cells remained pluripotent both in vitro and in vivo. Although Oct4 and Nanog levels were similar between the two cell lines, fluorescence correla=on spectroscopy (FCS) experiments showed different protein dynamics of these TFs and of heterochroma=n protein 1 (HP1), sugges=ng an altered chroma=n structure in KO cells. Remarkably, along a neural progenitor differen=a=on protocol, Kat6b-/- mESC gave rise to a higher number of cells at the end of the protocol respect to WT. Addi=onally, KO cells presented lower expression of the neural progenitor marker Sox1, and higher levels of the mesoderm marker Brachyury, sugges=ng a reduced efficiency to neural differen=a=on. Our results suggest that Kat6b is relevant in the maintenance of normal TFs dynamics and chroma=n organiza=on, and in neural differen=a=on of mESC. Comprehension of ESC epigene=c regula=on is cri=cal to unravel the mechanisms involved in cell fate choices and to make possible promising stem cells? applica=ons.