Differential incorporation of beta-actin as a component of RNA polymerase II into regulatory regions of stemness/differentiation genes in retinoic acid-induced differentiated human embryonic carcinoma cells

Objective: Nuclear actin is involved in transcription regulation by recruitment of histone modifiers and chromatin remodelers to the regulatory regions of active genes. In recent years, further attention has been focused on the role of actin as a nuclear protein in transcriptional processes. In the current study, the epigenetic role of nuclear actin on transcription regulation of two stemness [OCT4 and NANOG] and two differentiation] NESTIN and PAX6] marker genes was evaluated in a human embryonal carcinoma cell line [NT2] before and after differentiation induction

Materials and Methods: In this experimental study, differentiation of embryonal cells was induced by retinoic acid [RA], and quantitative real-time polymerase chain reaction [PCR] was used to evaluate differential expression of marker genes before and 3 days after RA- induced differentiation. Chromatin immunoprecipitation [ChIP] coupled with real-time PCR was then undertaken to monitor the incorporation of beta-actin, as a functional component of RNA polymerase II, in the regulatory regions of marker genes

Results: Data showed significant change in nuclear actin incorporation into the promoter regions of NESTIN and PAX6 after RA-induction

Conclusion: We emphasize the dynamic functional role of nuclear actin in differentiation of embryonal cells and its role as a subunit of RNA polymerase II

potential roles of actin in the nucleus

Over the past few decades, actin's presence in the nucleus has been demonstrated. Actin is a key protein necessary for different nuclear processes. Although actin is well known for its functional role in dynamic behavior of the cytoskeleton, emerging studies are now highlighting new roles for actin. At the present time there is no doubt about the presence of actin in the nucleus. A number of studies have uncovered the functional involvement of actin in nuclear processes. Actin as one of the nuclear components has its own structured and functional rules, such as nuclear matrix association, chromatin remodeling, transcription by RNA polymerases I, II, III and mRNA processing. In this historical review, we attempt to provide an overview of our current understanding of the functions of actin in the nucleus