Abstract
Protein kinases C (PKCs) are a family of serine/threonine kinases that are critical for signal transduction pathways involved in growth, differentiation and cell death. All PKC isoforms have four conserved domains, C1-C4. The C1 domain contains cysteine-rich finger-like motifs, which bind two zinc atoms. The zinc-finger motifs modulate diacylglycerol binding; thus, intracellular zinc concentrations could influence the activity and localization of PKC family members. 3T3 cells were cultured in zinc-deficient or zinc-supplemented medium for up to 32 h. Cells cultured in zinc-deficient medium had decreased zinc content, lowered cytosolic classical PKC activity, increased caspase-3 processing and activity, and reduced cell number. Zinc-deficient cytosols had decreased activity and expression levels of PKC-α, whereas PKC-α phosphorylation was not altered. Inhibition of PKC-α with Gö6976 had no effect on cell number in the zinc-deficient group. Proteolysis of the novel PKC family member, PKC-δ, to its 40-kDa catalytic fragment occurred in cells cultured in the zinc-deficient medium. Occurrence of the PKC-δ fragment in mitochondria was co-incident with caspase-3 activation. Addition of the PKC-δ inhibitor, rottlerin, or zinc to deficient medium reduced or eliminated proteolysis of PKC-δ, activated caspase-3 and restored cell number. Inhibition of caspase-3 processing by Z-DQMD-FMK (Z-Asp-Gln-Met-Asp- fluoromethylketone) did not restore cell number in the zinc-deficient group, but resulted in processing of full-length PKC-δ to a 56-kDa fragment. These results support the concept that intracellular zinc concentrations influence PKC activity and processing, and that zinc-deficiency-induced apoptosis occurs in part through PKC-dependent pathways.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 63-71 |
| Number of pages | 9 |
| Journal | Biochemical Journal |
| Volume | 383 |
| Issue number | 1 |
| DOIs | |
| State | Published - Oct 1 2004 |
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Keywords
- 3T3 cell
- Apoptosis
- Caspase-3
- Protein kinase C-α
- Protein kinase C-δ
- Zinc
ASJC Scopus subject areas
- Biochemistry
Cite this
Alterations in protein kinase C activity and processing during zinc-deficiency-induced cell death. / Chou, Susan S.; Clegg, Michael S.; Momma, Tony Y.; Niles, Brad J.; Duffy, Jodie Y.; Daston, George P.; Keen, Carl L.
In: Biochemical Journal, Vol. 383, No. 1, 01.10.2004, p. 63-71.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Alterations in protein kinase C activity and processing during zinc-deficiency-induced cell death
AU - Chou, Susan S.
AU - Clegg, Michael S.
AU - Momma, Tony Y.
AU - Niles, Brad J.
AU - Duffy, Jodie Y.
AU - Daston, George P.
AU - Keen, Carl L
PY - 2004/10/1
Y1 - 2004/10/1
N2 - Protein kinases C (PKCs) are a family of serine/threonine kinases that are critical for signal transduction pathways involved in growth, differentiation and cell death. All PKC isoforms have four conserved domains, C1-C4. The C1 domain contains cysteine-rich finger-like motifs, which bind two zinc atoms. The zinc-finger motifs modulate diacylglycerol binding; thus, intracellular zinc concentrations could influence the activity and localization of PKC family members. 3T3 cells were cultured in zinc-deficient or zinc-supplemented medium for up to 32 h. Cells cultured in zinc-deficient medium had decreased zinc content, lowered cytosolic classical PKC activity, increased caspase-3 processing and activity, and reduced cell number. Zinc-deficient cytosols had decreased activity and expression levels of PKC-α, whereas PKC-α phosphorylation was not altered. Inhibition of PKC-α with Gö6976 had no effect on cell number in the zinc-deficient group. Proteolysis of the novel PKC family member, PKC-δ, to its 40-kDa catalytic fragment occurred in cells cultured in the zinc-deficient medium. Occurrence of the PKC-δ fragment in mitochondria was co-incident with caspase-3 activation. Addition of the PKC-δ inhibitor, rottlerin, or zinc to deficient medium reduced or eliminated proteolysis of PKC-δ, activated caspase-3 and restored cell number. Inhibition of caspase-3 processing by Z-DQMD-FMK (Z-Asp-Gln-Met-Asp- fluoromethylketone) did not restore cell number in the zinc-deficient group, but resulted in processing of full-length PKC-δ to a 56-kDa fragment. These results support the concept that intracellular zinc concentrations influence PKC activity and processing, and that zinc-deficiency-induced apoptosis occurs in part through PKC-dependent pathways.
AB - Protein kinases C (PKCs) are a family of serine/threonine kinases that are critical for signal transduction pathways involved in growth, differentiation and cell death. All PKC isoforms have four conserved domains, C1-C4. The C1 domain contains cysteine-rich finger-like motifs, which bind two zinc atoms. The zinc-finger motifs modulate diacylglycerol binding; thus, intracellular zinc concentrations could influence the activity and localization of PKC family members. 3T3 cells were cultured in zinc-deficient or zinc-supplemented medium for up to 32 h. Cells cultured in zinc-deficient medium had decreased zinc content, lowered cytosolic classical PKC activity, increased caspase-3 processing and activity, and reduced cell number. Zinc-deficient cytosols had decreased activity and expression levels of PKC-α, whereas PKC-α phosphorylation was not altered. Inhibition of PKC-α with Gö6976 had no effect on cell number in the zinc-deficient group. Proteolysis of the novel PKC family member, PKC-δ, to its 40-kDa catalytic fragment occurred in cells cultured in the zinc-deficient medium. Occurrence of the PKC-δ fragment in mitochondria was co-incident with caspase-3 activation. Addition of the PKC-δ inhibitor, rottlerin, or zinc to deficient medium reduced or eliminated proteolysis of PKC-δ, activated caspase-3 and restored cell number. Inhibition of caspase-3 processing by Z-DQMD-FMK (Z-Asp-Gln-Met-Asp- fluoromethylketone) did not restore cell number in the zinc-deficient group, but resulted in processing of full-length PKC-δ to a 56-kDa fragment. These results support the concept that intracellular zinc concentrations influence PKC activity and processing, and that zinc-deficiency-induced apoptosis occurs in part through PKC-dependent pathways.
KW - 3T3 cell
KW - Apoptosis
KW - Caspase-3
KW - Protein kinase C-α
KW - Protein kinase C-δ
KW - Zinc
UR - http://www.scopus.com/inward/record.url?scp=6344240735&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=6344240735&partnerID=8YFLogxK
U2 - 10.1042/BJ20040074
DO - 10.1042/BJ20040074
M3 - Article
C2 - 15198639
AN - SCOPUS:6344240735
VL - 383
SP - 63
EP - 71
JO - Biochemical Journal
JF - Biochemical Journal
SN - 0264-6021
IS - 1
ER -