Transcriptional activation of PRMT5 by NF-Y is required for cell growth and negatively regulated by the PKC/c-Fos signaling in prostate cancer cells

Abstract

Protein arginine methyltransferase 5 (PRMT5) symmetrically methylates arginine residues of histones and non-histone protein substrates and regulates a variety of cellular processes through epigenetic control of target gene expression or post-translational modification of signaling molecules. Recent evidence suggests that PRMT5 may function as an oncogene and its overexpression contributes to the development and progression of several human cancers. However, the mechanism underlying the regulation of PRMT5 expression in cancer cells remains largely unknown. In the present study, we have mapped the proximal promoter of PRMT5 to the −240 bp region and identified nuclear transcription factor Y (NF-Y) as a critical transcription factor that binds to the two inverted CCAAT boxes and regulates PRMT5 expression in multiple cancer cell lines. Further, we present evidence that loss of PRMT5 is responsible for cell growth inhibition induced by knockdown of NF-YA, a subunit of NF-Y that forms a heterotrimeric complex with NF-YB and NF-YC for function. Significantly, we have found that activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) in LNCaP prostate cancer cells down-regulates the expression of NF-YA and PRMT5 at the transcription level in a c-Fos-dependent manner. Given that down-regulation of several PKC isozymes is implicated in the development and progression of several human cancers, our findings suggest that the PKC-c-Fos-NF-Y signaling pathway may be responsible for PRMT5 overexpression in a subset of human cancer patients.

The E3 ubiquitin ligase CHIP mediates ubiquitination and proteasomal degradation of PRMT5

“…The pCMV-Myc-PRMT5 expression plasmid was previously constructed [12], and was used as a template to generate methyltransferase activity-deficient mutant pCMV-Myc-PRMT5-R368A [29], and a series of truncated fragments covering the residues 229–637, 284–637, 352–637, and 451–637. For mutagenesis, nucleotide substitutions (from lysine/K to arginine/R) were introduced into PRMT5 using ligation PCR as described previously [12, 30].…”

“…For mutagenesis, nucleotide substitutions (from lysine/K to arginine/R) were introduced into PRMT5 using ligation PCR as described previously [12, 30]. pCMV-FLAG-PRMT5 was generated by subcloning PRMT5 into pCMV-FLAG expression vector (Sigma).…”

“…We have previously demonstrated that in human prostate cancer cells, PRMT5 can be transcriptionally activated by nuclear factor Y (NF-Y), and that the protein kinase C (PKC)/c-Fos signaling pathway negatively regulates PRMT5 expression through transcriptional down-regulation of NF-Y [12]. Recent research has also found that MYC directly up-regulates the transcription of the core small nuclear ribonucleoprotein particle (snRNP) assembly genes, in which PRMT5 is the key enzymatic component [13].…”

Inhibition of PKCα reduces the ability of migration of kidney cancer cells but has no impact on cell apoptosis

“…The upregulation or downregulation of PKC and their isoenzyme or their biological effect had previously been studied in human tumor samples (13)(14)(15)(16)(17). Downregulation of PKC isozymes was associated with the occurrence and progression of several human cancer types.…”

PKCα–GSK3β–NF-κB signaling pathway and the possible involvement of TRIM21 in TRAIL-induced apoptosis

“…Protein kinase C (PKC), a family of serine/threonine protein kinases, is activated by numerous stimuli and has versatile biological functions including regulating cell proliferation, survival, and apoptosis (Griner and Kazanietz, 2007;Chen et al, 2011;Zhang et al, 2014a). PKC isozymes can be classified into three subtypes (Spitaler and Cantrell, 2004): 1) the conventional cPKCs (α, β, γ), activated by diacylglycerol (DAG), calcium, or phosphatidylserine; 2) the novel D r a f t 5 nPKCs (δ, ε, η, θ), activated by DAG and independent on calcium; and 3) the atypical aPKCs (ζ, λ/ι), activated by phosphatidylserine and independent on calcium and DAG.…”