Proteolysis‐inducing factor regulates hepatic gene expression via the transcription factors NF‐κΒ and STAT3

Watchorn, Tammy; Waddell, Ian D.; Dowidar, Nabil; Ross, James A.

doi:10.1096/fj.00-0534fje

Cited by 99 publications

(89 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This may be essential to its function as a cachetic factor, as dermcidin expression does not appear sufficient to induce cachexia (Monitto et al, 2004). Similarly, deglycosylated PIF lacks proteolytic activity in murine gastrocnemius muscle (Todorov et al, 1996(Todorov et al, , 1997, and in our experiments it was the fully glycosylated PIF molecule that influenced hepatic cell NF-kB and STAT3 activity and gene expression (Watchorn et al, 2001(Watchorn et al, , 2002. However, the PIF aminoacid sequence lacks typical consensus N-and O-glycosylation sites and the mechanism of glycosylation remains unknown.…”

mentioning

confidence: 74%

“…Screening of tissues for PIF binding demonstrated substantial binding only to skeletal muscle and liver (unpublished observation), and we have investigated the effect of PIF on liver cells. In primary hepatocytes and HepG2 cells, PIF was found to activate the transcription factors NF-kB and STAT3, resulting in the stimulation of IL-8, IL-6 and CRP production, and the inhibition of transferrin production (Watchorn et al, 2001). Proteolysis-inducing factor was also found to induce the expression of NF-kB, IL-6, IL-8, ICAM-1 and VCAM and the shedding of syndecans in the liver endothelial cell line SK-HEP-1 and human umbilical vein endothelial cells, but not in pulmonary artery endothelial cells (Watchorn et al, 2002).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Dermcidin expression in hepatic cells improves survival without N-glycosylation, but requires asparagine residues

et al. 2006

View full text Add to dashboard Cite

Proteolysis-inducing factor, a cachexia-inducing tumour product, is an N-glycosylated peptide with homology to the unglycosylated neuronal survival peptide Y-P30 and a predicted product of the dermcidin gene, a pro-survival oncogene in breast cancer. We aimed to investigate whether dermcidin is pro-survival in liver cells, in which proteolysis-inducing factor induces catabolism, and to determine the role of potentially glycosylated asparagine residues in this function. Reverse cloning of proteolysis-inducing factor demonstrated B100% homology with the dermcidin cDNA. This cDNA was cloned into pcDNA3.1 þ and both asparagine residues removed using site-directed mutagenesis. In vitro translation demonstrated signal peptide production, but no difference in molecular weight between the products of native and mutant vectors. Immunocytochemistry of HuH7 cells transiently transfected with V5-His-tagged dermcidin confirmed targeting to the secretory pathway. Stable transfection conferred protection against oxidative stress. This was abrogated by mutation of both asparagines in combination, but not by mutation of either asparagine alone. These findings suggest that dermcidin may function as an oncogene in hepatic as well as breast cells. Glycosylation does not appear to be required, but the importance of asparagine residues suggests a role for the proteolysis-inducing factor core peptide domain.

show abstract

mentioning

confidence: 74%

mentioning

confidence: 99%

Dermcidin expression in hepatic cells improves survival without N-glycosylation, but requires asparagine residues

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Proteolysis-inducing factor has also been shown to activate NFkB in primary hepatocytes and the human cancer cell line HepG2, resulting in the increased production of interleukin-6 and -8 (IL-6 and IL-8) and C-reactive protein and the decreased production of transferrin (Watchorn et al, 2001). There was also an increase in ICAM-1, another NF-kB-inducible gene.…”

Section: Discussionmentioning

confidence: 99%

NF-κB mediates proteolysis-inducing factor induced protein degradation and expression of the ubiquitin–proteasome system in skeletal muscle

2005

View full text Add to dashboard Cite

Loss of skeletal muscle in cancer cachexia has a negative effect on both morbidity and mortality. The role of nuclear factor-kB (NFkB) in regulating muscle protein degradation and expression of the ubiquitin -proteasome proteolytic pathway in response to a tumour cachectic factor, proteolysis-inducing factor (PIF), has been studied by creating stable, transdominant-negative, muscle cell lines. Murine C 2 C 12 myoblasts were transfected with plasmids with a CMV promoter that had mutations at the serine phosphorylation sites required for degradation of I-kBa, an NF-kB inhibitory protein, and allowed to differentiate into myotubes. Proteolysis-inducing factor induced degradation of I-kBa, nuclear accumulation of NF-kB and an increase in luciferase reporter gene activity in myotubes containing wild-type, but not mutant, I-kBa proteins. Proteolysis-inducing factor also induced total protein degradation and loss of the myofibrillar protein myosin in myotubes containing wild-type, but not mutant, plasmids at the same concentrations as those causing activation of NF-kB. Proteolysis-inducing factor also induced increased expression of the ubiquitinproteasome pathway, as determined by 'chymotrypsin-like' enzyme activity, the predominant proteolytic activity of the b-subunits of the proteasome, protein expression of 20S a-subunits and the 19S subunits MSS1 and p42, as well as the ubiquitin conjugating enzyme, E2 14k , in cells containing wild-type, but not mutant, I-kBa. The ability of mutant I-kBa to inhibit PIF-induced protein degradation, as well as expression of the ubiquitin -proteasome pathway, confirms that both of these responses depend on initiation of transcription by NF-kB.

show abstract

“…This suggests that EPA also affects a downstream pathway involved in induction of proteasome expression by 15(S)-HETE, possibly a nuclear transcription factor, since Ross et al (1999) have shown that in the pancreatic cancer cell line, MiaPaCa 2, exposed to EPA for 2 h prior to a pulse of TNF-a, I-kBa was preserved, suggesting an effect of EPA in stabilising the NF-kB complex in the cytoplasm. Watchorn et al (2001) have shown PIF to activate both the transcription factors NF-kB and STAT3 in hepatic cells. Li et al (1998) showed that TNF-a stimulated protein loss in C 2 C 12 myotubes involved the ubiquitin -proteasome proteolytic pathway and was accompanied by nuclear translocation of NF-kB to its targeted DNA sequence by stimulating phosphorylation, ubiquitin conjugation and proteolysis of I-kBa.…”

Section: Discussionmentioning

confidence: 99%

Induction of protein catabolism in myotubes by 15(S)-hydroxyeicosatetraenoic acid through increased expression of the ubiquitin–proteasome pathway

2003

View full text Add to dashboard Cite

The potential role of 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) as an intracellular signal for increased protein catabolism and induction of the expression of key components of the ubiquitin -proteasome proteolytic pathway induced by a tumour cachectic factor, proteolysis-inducing factor has been studied in murine C 2 C 12 myotubes. 15(S)-HETE induced protein degradation in these cells with a maximal effect at concentrations between 78 and 312 nM. The effect was attenuated by the polyunsaturated fatty acid, eicosapentaenoic acid (EPA). There was an increase in 'chymotrypsin-like' enzyme activity, the predominant proteolytic activity of the proteasome, in the same concentration range as that inducing total protein degradation, and this effect was also attenuated by EPA. 15(S)-hydroxyeicosatetraenoic acid also increased maximal expression of mRNA for proteasome subunits C2 and C5, as well as the ubiquitin-conjugating enzyme, E2 14k , after 4 h incubation, as determined by quantitative competitive RT -PCR. The concentrations of 15-HETE affecting gene expression were the same as those inducing protein degradation. Western blotting of cellular supernatants of myotubes treated with 15(S)-HETE for 24 h showed increased expression of p42, an ATPase subunit of the regulatory complex at similar concentrations, as well as a decrease in expression of myosin in the same concentration range. 15(S)-hydroxyeicosatetraenoic acid activated binding of nuclear factor-kB (NF-kB) in the myotube nucleus and stimulated degradation of I-kBa. The effect on the NF-kB/I-kBa system was attenuated by EPA. In addition, the NF-kB inhibitor peptide SN50 attenuated the increased chymotrypsinlike enzyme activity in the presence of 15(S)-HETE. These results suggest that 15(S)-HETE induces degradation of myofibrillar proteins in differentiated myotubes through an induction of an increased expression of the regulatory components of the ubiquitinproteasome proteolytic pathway possibly through the intervention of the nuclear transcription factor NF-kB, and that this process is inhibited by EPA.

show abstract

Proteolysis‐inducing factor regulates hepatic gene expression via the transcription factors NF‐κΒ and STAT3

Cited by 99 publications

References 28 publications

Dermcidin expression in hepatic cells improves survival without N-glycosylation, but requires asparagine residues

Dermcidin expression in hepatic cells improves survival without N-glycosylation, but requires asparagine residues

NF-κB mediates proteolysis-inducing factor induced protein degradation and expression of the ubiquitin–proteasome system in skeletal muscle

Induction of protein catabolism in myotubes by 15(S)-hydroxyeicosatetraenoic acid through increased expression of the ubiquitin–proteasome pathway

Contact Info

Product

Resources

About