instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: Protein kinase D (PKD or PKD1) is a serine/threonine protein kinase that has been shown to play a role in a variety of cellular processes; however, the function of PKD1 in the skin has not been fully investigated. The balance between proliferation and differentiation processes in the predominant cells of the epidermis, the keratinocytes, is essential for normal skin function.', 'To investigate the effect of PKD1 deficiency on proliferation and differentiation of epidermal keratinocytes.', 'We utilized a floxed PKD1 mouse model such that infecting epidermal keratinocytes derived from these mice with an adenovirus expressing Cre-recombinase allowed us to determine the effect of PKD1 gene loss in vitro. Proliferation and differentiation were monitored using qRT-PCR, Western blot, transglutaminase activity assays, [3H]thymidine incorporation into DNA and cell cycle analysis.', 'A significant decrease in PKD1 mRNA and protein levels was achieved in adenoviral Cre-recombinase-infected cells. Deficiency of PKD1 resulted in significant increases in the mRNA and protein expression of various differentiation markers such as loricrin, involucrin, and keratin 10 either basally and/or upon stimulation of differentiation. PKD1-deficient keratinocytes also showed an increase in transglutaminase expression and activity, indicating an anti-differentiative role of PKD1. Furthermore, the PKD1-deficient keratinocytes exhibited decreased proliferation. However, PKD1 loss had no effect on stem cell marker expression.\Question: Does protein kinase D1 deficiency promote differentiation in epidermal keratinocytes?
answer:
Cre-recombinase-mediated knockdown represents an additional approach demonstrating that PKD1 is an anti-differentiative, pro-proliferative signal in mouse keratinocytes.

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Context: Transient receptor potential ankyrin 1 (TRPA1) is a membrane-associated cation channel, widely expressed in neuronal cells and involved in nociception and neurogenic inflammation. We showed recently that TRPA1 mediates cartilage degradation and joint pain in the MIA-model of osteoarthritis (OA) suggesting a hitherto unknown role for TRPA1 in OA. Therefore, we aimed to investigate whether TRPA1 is expressed and functional in human OA chondrocytes.', 'Expression of TRPA1 in primary human OA chondrocytes was assessed by qRT-PCR and Western blot. The functionality of the TRPA1 channel was assessed by Ca(2+)-influx measurements. Production of MMP-1, MMP-3, MMP-13, IL-6, and PGE2 subsequent to TRPA1 activation was measured by immunoassay.', 'We show here for the first time that TRPA1 is expressed in primary human OA chondrocytes and its expression is increased following stimulation with inflammatory factors IL-1, IL-17, LPS, and resistin. Further, the TRPA1 channel was found to be functional, as stimulation with the TRPA1 agonist AITC caused an increase in Ca(2+) influx, which was attenuated by the TRPA1 antagonist HC-030031. Genetic depletion and pharmacological inhibition of TRPA1 downregulated the production of MMP-1, MMP-3, MMP-13, IL-6, and PGE2 in osteoarthritic chondrocytes and murine cartilage, respectively.\Question: Is transient receptor potential ankyrin 1 ( TRPA1 ) functionally expressed in primary human osteoarthritic chondrocytes?
answer:
The TRPA1 cation channel was found to be functionally expressed in primary human OA chondrocytes, which is an original finding. The presence and inflammatory and catabolic effects of TRPA1 in human OA chondrocytes propose a highly intriguing role for TRPA1 as a pathogenic factor and drug target in OA.

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Context: The peptidyl-proline isomerase, Protein Never in Mitosis Gene A Interacting-1 (PIN1), regulates turnover of inducible nitric oxide synthase (iNOS) in murine aortic endothelial cells (MAEC) stimulated with E. coli endotoxin (LPS) and interferon-gamma (IFN). Degradation of iNOS was reduced by a calpain inhibitor, suggesting that PIN1 may affect induction of other calpain-sensitive inflammatory proteins, such as cyclooxygenase (COX)-2, in MAEC.', 'MAEC, transduced with lentivirus encoding an inactive control short hairpin (sh) RNA or one targeting PIN1 that reduced PIN1 by 85%, were used. Cells were treated with LPS/IFN, calpain inhibitors (carbobenzoxy-valinyl-phenylalaninal (zVF), PD150606), cycloheximide and COX inhibitors to determine the effect of PIN1 depletion on COX-2 and calpain.', 'LPS or IFN alone did not induce COX-2. However, treatment with 10 mug LPS plus 20 ng IFN per ml induced COX-2 protein 10-fold in Control shRNA MAEC. Induction was significantly greater (47-fold) in PIN1 shRNA cells. COX-2-dependent prostaglandin E2 production increased 3-fold in KD MAEC, but did not increase in Control cells. The additional increase in COX-2 protein due to PIN1 depletion was post-transcriptional, as induction of COX-2 mRNA by LPS/IFN was the same in cells containing or lacking PIN1. Instead, the loss of COX-2 protein, after treatment with cycloheximide to block protein synthesis, was reduced in cells lacking PIN1 in comparison with Control cells, indicating that degradation of the enzyme was reduced. zVF and PD150606 each enhanced the induction of COX-2 by LPS/IFN. zVF also slowed the loss of COX-2 after treatment with cycloheximide, and COX-2 was degraded by exogenous mu-calpain in vitro. In contrast to iNOS, physical interaction between COX-2 and PIN1 was not detected, suggesting that effects of PIN1 on calpain, rather than COX-2 itself, affect COX-2 degradation. While cathepsin activity was unaltered, depletion of PIN1 reduced calpain activity by 55% in comparison with Control shRNA cells.\Question: Does protein Never in Mitosis Gene A Interacting-1 regulate calpain activity and the degradation of cyclooxygenase-2 in endothelial cells?
answer:
PIN1 reduced calpain activity and slowed the degradation of COX-2 in MAEC, an effect recapitulated by an inhibitor of calpain. Given the sensitivity of COX-2 and iNOS to calpain, PIN1 may normally limit induction of these and other calpain substrates by maintaining calpain activity in endothelial cells.