Abstract
BackgroundPar14, a member of the parvulin family of peptidyl-prolyl cis-trans isomerases that is involved in rRNA processing, microtubule formation and the glucose metabolism and has been suggested to play a role in chromatin remodeling on basis of sequence and structural identities to HMG proteins. Par14 is enriched in the nucleus and binds to double-stranded DNA in vitro.ResultsBy means of sub-nuclear biochemical fractionations, we demonstrate that cellular Par14 is associated with chromatin 3-fold higher than with the nuclear matrix in vivo. Par14 is released from the chromatin fraction after treatment with DNase I and elutes at high NaCl concentrations from the nucleic acid-binding fraction. Using qRT-PCR and western blotting we demonstrate that Par14 is up-regulated during the S and G2/M phases in synchronised human foreskin fibroblasts cells.ConclusionIn the light of our results, Par14 can be described as an endogenous non-histone chromatin protein, which binds DNA in vivo. We propose that Par14 is involved in a DNA-dependent activity such as transcription.
Highlights
Parvulin 14 (Par14), a member of the parvulin family of peptidyl-prolyl cis-trans isomerases that is involved in rRNA processing, microtubule formation and the glucose metabolism and has been suggested to play a role in chromatin remodeling on basis of sequence and structural identities to High Mobility Group (HMG) proteins
Together with total cell extract (TCE) and recombinant Par14 these fractions were run on a SDS-PAGE gel, which was further analyzed by western blotting and densitometry (Figure 1B and C)
From the Par14 band signal in S2+ (Figure 1B) it is deduced that Par14 was 1.4-fold released from chromatin when treated with DNase I as opposed to S2, which did not undergo any nuclease treatment
Summary
A member of the parvulin family of peptidyl-prolyl cis-trans isomerases that is involved in rRNA processing, microtubule formation and the glucose metabolism and has been suggested to play a role in chromatin remodeling on basis of sequence and structural identities to HMG proteins. A role for peptidyl-prolyl cis/trans isomerases (PPIases) in the folding of newly synthesized proteins was inferred and chaperone-like activity has been associated with several PPIases [2,3]. Par and its isoform Par belong to a class of PPIases called parvulins. Both proteins are encoded by the gene PIN4 which is located on chromosome Xq13.1 within the human genome [8]. Human Par has a molecular weight of 14 kDa [9] and consists
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