Selective depletion of mouse kidney proximal straight tubule cells causes acute kidney injury.

The proximal straight tubule (S3 segment) of the kidney is highly susceptible to ischemia and toxic insults but has a remarkable capacity to repair its structure and function. In response to such injuries, complex processes take place to regenerate the epithelial cells of the S3 segment; however, the precise molecular mechanisms of this regeneration are still being investigated. By applying the "toxin receptor mediated cell knockout" method under the control of the S3 segment-specific promoter/enhancer, Gsl5, which drives core 2 β-1,6-N-acetylglucosaminyltransferase gene expression, we established a transgenic mouse line expressing the human diphtheria toxin (DT) receptor only in the S3 segment.

Protein kinase Cepsilon: multiple roles in the function of, and signaling mediated by, the cytoskeleton.

Recent studies have established essential roles of protein kinase Cepsilon in signaling pathways controlling various functions of microfilaments and intermediate filaments by modulating multiple cytoskeletal proteins. This review summarizes recent progress in our understanding of the roles of protein kinase Cepsilon in the functions and signaling of microfilaments and intermediate filaments, with a focus mainly on cell-matrix and cell-cell interactions, migrations and contraction, in addition to its relevance in the development of several diseases, such as malignant tumors or cardiac disease.

Protein kinase Cepsilon: the mitochondria-mediated signaling pathway.

Mitochondria, which are the cellular energy plants, also act as the integration center of cellular signaling pathways. Apoptosis is a well-known pathway in which mitochondria are involved. Protein kinase Cepsilon has been classified as a novel type of protein kinase C and is involved in many cellular events regulating mitochondrial function.

Protein kinase C epsilon phosphorylates keratin 8 at Ser8 and Ser23 in GH4C1 cells stimulated by thyrotropin-releasing hormone.

Protein kinase C epsilon (PKCepsilon) is activated by thyrotropin-releasing hormone (TRH), a regulator of pituitary function in rat pituitary GH(4)C(1) cells. We analyzed the downstream mechanism after PKCepsilon activation. Exposure of GH(4)C(1) cells to TRH or a phorbol ester increased the phosphorylation of three p52 proteins (p52a, p52b and p52c) and decreased the phosphorylation of destrin and cofilin.

Identification of phosphoproteins associated with maintenance of transformed state in temperature-sensitive Rous sarcoma-virus infected cells by proteomic analysis.

To identify phosphotyrosine-containing proteins essential for maintaining the transformed state, we studied the tyrosine phosphorylation profile of temperature-sensitive mutant of Rous sarcoma virus, tsNY68, infected cells (68N7). Shifting the temperature from 39 degrees C (nonpermissive) to 32 degrees C (permissive) markedly increased the expression of phosphotyrosine-containing cell membrane proteins of approximately 40kDa, as assessed by SDS-PAGE. Membrane and nuclear proteins were separated by two-dimensional gel electrophoresis and immunoblotted with anti-phosphotyrosine antibody.

The second phase activation of protein kinase C delta at late G1 is required for DNA synthesis in serum-induced cell cycle progression.

Background: Cell lines that stably over-express protein kinase C (PKC) delta frequently show a decrease in growth rate and saturation density, leading to the hypothesis that PKC delta has a negative effect on cell proliferation. However, the mode of PKC delta activation, the cell cycle stage requiring PKC delta activity, and the exact role of PKC delta at that stage remains unknown.

Results: Here we show that the treatment of quiescent fibroblasts with serum activates PKC delta at two distinct time points, within 10 min after serum treatment, and for a longer duration between 6 and 10 h.

Protein kinase C-epsilon (PKC-epsilon): its unique structure and function.

Protein kinase C (PKC)-epsilon was first discovered among novel PKC isotypes by cDNA cloning, and characterized as a calcium-independent but phorbol ester/diacylglycerol-sensitive serine/threonine kinase. PKC-epsilon is targeted to a specific cellular compartment in a manner dependent on second messengers and on specific adapter proteins in response to extracellular signals that activate G-protein-coupled receptors, tyrosine kinase receptors, or tyrosine kinase-coupled receptors. PKC-epsilon then regulates various physiological functions including the activation of nervous, endocrine, exocrine, inflammatory, and immune systems.

Role of specific protein kinase C isozymes in mediating epidermal growth factor, thyrotropin-releasing hormone, and phorbol ester regulation of the rat prolactin promoter in GH4/GH4C1 pituitary cells.

Epidermal growth factor (EGF) and TRH both produce enhanced prolactin (PRL) gene transcription and PRL secretion in GH4 rat pituitary tumor cell lines. These agents also activate protein kinase C (PKC) in these cells. Previous studies have implicated the PKCepsilon isozyme in mediating TRH-induced PRL secretion.