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Protein kinase C activation and phosphate uptake are altered in intact mucolipidosis type-4 skin fibroblasts
1Department of Paediatrics, Hadassah University Hospital, Mt. Scopus, Jerusalem, Israel.
Abstract:
Mucolipidosis type 4 (ML-4) is an autosomal recessive inborn error of metabolism, the pathogenesis of which is not known. We characterized protein kinase C (PKC) activation and cellular phosphate uptake in intact quiescent ML-4 skin fibroblasts and after stimulation with phorbol myristate acetate (PMA). [3H]Phorbol dibutyrate uptake was not altered in ML-4 compared to control cells. Translocation of PKC from the cytosolic to the membranous compartment upon stimulation with PMA was perturbed in ML-4 cells. Phosphate uptake was reduced in both cytosolic and membranous fractions of quiescent ML-4 cells. Stimulation with PMA did not elicit an increase in phosphate uptake in the cytosolic fraction of ML-4 cells compared with control cells, but led to comparable phosphate uptake in the membranous fraction of both cell types. The data indicate that PKC-mediated signal transduction may be perturbed in ML-4. Other kinases and phosphatases may be involved. These alterations may play an important role in the pathogenesis of this disorder.
Insights
Mucolipidosis type 4 (ML-4) involves altered protein kinase C (PKC) activation and phosphate uptake. These cellular defects may contribute to the pathogenesis of this metabolic disorder.
Area of Science:
- Biochemistry
- Cell Biology
- Genetics
Background:
- Mucolipidosis type 4 (ML-4) is an autosomal recessive metabolic disorder with unknown pathogenesis.
- Cellular signaling pathways, including protein kinase C (PKC) activation, are crucial for normal cell function.
Purpose of the Study:
- To investigate protein kinase C (PKC) activation and cellular phosphate uptake in ML-4 fibroblasts.
- To explore the role of PKC-mediated signal transduction in the pathogenesis of ML-4.
Main Methods:
- Characterization of PKC activation and translocation in response to phorbol myristate acetate (PMA) in ML-4 fibroblasts.
- Measurement of cellular phosphate uptake in both quiescent and stimulated ML-4 and control fibroblasts.
Main Results:
- Phorbol myristate acetate (PMA) stimulation perturbed the translocation of PKC in ML-4 cells.
- Phosphate uptake was reduced in both cytosolic and membranous fractions of quiescent ML-4 cells.
- PMA stimulation did not increase cytosolic phosphate uptake in ML-4 cells, unlike in controls.
Conclusions:
- PKC-mediated signal transduction appears to be perturbed in ML-4.
- Altered PKC signaling and phosphate uptake may contribute to the pathogenesis of ML-4.
- Further investigation into other kinases and phosphatases is warranted.
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