HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

pPKCδ activates SC35 splicing factor during H9c2 myoblastic differentiation

Susi Zara1, Mirella Falconi2, Monica Rapino3, Michela Zago2, Giovanna Orsini4, Giovanni Mazzotti5, Amelia Cataldi6 and Gabriella Teti5

1Department of Drug Sciences, Section of Human Anatomy, Faculty of Pharmacy, University “G. d’ Annunzio”, Chieti-Pescara, 2Department of Anatomic Sciences, Scientific Pole of Rimini, Alma Mater Studiorum, University of Bologna, 3Institute of Molecular Genetics CNR, Unit of Chieti, 4Department of Restorative Dentistry, Institute of Stomatology, University of Marche, Ancona, 5Department of Anatomic Sciences, Alma Mater Studiorum, University of Bologna and 6Department Medicine and Ageing Sciences, Section of Human Anatomy, Faculty of Pharmacy, University “G. d’ Annunzio”, Chieti-Pescara, Italy.

Offprint requests to: Susi Zara, Section of Human Anatomy, Faculty of Pharmacy, University “G. d’ Annunzio”, Chieti-Pescara, Italy. e-mail: s.zara@unich.it


Summary. Although Protein Kinase C (PKC) isoforms’ role in the neonatal and adult cardiac tissue development and ageing has been widely described “in vivo”, the interaction of such enzymes with specific nuclear substrates needs to be investigated.
The aim of our research has been the study of the expression, localization and interaction with the splicing factor SC35 of PKC isoforms (α, δ, ε, ζ) and their potential role in modulating the transcription machinery.
H9c2 cells induced to myoblast differentiation in the presence of 1% Horse Serum (HS) have represented our experimental model. The expression of PKC isoforms, their distribution and interaction with SC35 have been evaluated by western blotting, co-immunoprecipitation and double gold immunolabeling for transmission and scanning electron microscopy.
Our results show PKC
δ as the most expressed isoform in differentiated cells. Surprisingly, the distribution of PKCδ and SC35 does not show any significant modification between 10%FBS and 1%HS treated samples and no co-localization is observed. Moreover the interaction between the phosphorylated form of PKCδ (pPKCδ) and SC35 increases, is distributed and co-localizes within the nucleus of differentiated H9c2.
These data represent reasonable evidence of pPKC
δ mediated SC35 splicing factor activation, suggesting its direct effect on transcription via interaction with the transcription machinery. Furthermore, this co-localization represents a crucial event resulting in downstream changes in transcription of components which determine the morphological modifications related to cardiomyoblast differentiated phenotype. Histol Histopathol 26, 59-69 (2011)

Key words: PKCδ, pPKCδ, SC35, Myoblast differentiation

DOI: 10.14670/HH-26.59