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.

Input: Consider Input: 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?

Output: Cre-recombinase-mediated knockdown represents an additional approach demonstrating that PKD1 is an anti-differentiative, pro-proliferative signal in mouse keratinocytes.


Input: Consider Input: Context: We previously reported that human OA subchondral bone osteoblasts could be discriminated into two subpopulations identified by their levels of endogenous production (low [L] or high [H]) of PGE(2). Here, we investigated the OPG and RANKL expression levels, the histologic analysis of the subchondral bone as well as the osteoclast differentiation effect of osteoblasts on normal and both OA subpopulations (L and H), and further examined on the L OA osteoblasts the modulation of bone remodelling factors on the OPG and RANKL levels, as well as on the resorption activity.', 'Gene expression was determined using real-time PCR, PGE2 and OPG levels by specific ELISA, and membranous RANKL by flow cytometry. Histological observation of the subchondral bone was performed on human knee specimens. Osteoclast differentiation and formation was assayed by using the pre-osteoclastic cell line RAW 264.7. OPG and RANKL modulation on L OA osteoblasts was monitored following treatment with osteotropic factors, and the resorption activity was studied by the co-culture of differentiated PBMC/osteoblasts.', 'Human OA subchondral bone osteoblasts expressed less OPG than normal. Compared to normal, RANKL gene expression levels were increased in L OA and decreased in H OA cells. The OPG/RANKL mRNA ratio was significantly diminished in L OA compared to normal or H OA (p<0.02, p<0.03), and markedly increased in H OA compared to normal. Inhibition of endogenous PGE(2) levels by indomethacin markedly decreased the ratio of OPG/RANKL on the H OA. In contrast to H OA osteoblasts, L OA cells induced a significantly higher level of osteoclast differentiation and formation (p<0.05). Histological analysis showed a reduced subchondral bone on the L OA and an increased bone mass on the H OA compared to normal. Treatment of L OA osteoblasts with osteotropic factors revealed that the OPG/RANKL mRNA expression ratio was significantly reduced by vitamin D(3) and significantly increased by TNF-alpha, PTH and PGE(2), while IL-1Beta demonstrated no effect. OPG protein levels showed similar profiles. No true effect was noted on membranous RANKL upon treatment with IL-1Beta, PGE(2) and PTH, but a significant increase was observed with vitamin D3 and TNF-alpha. The resorption activity of the L OA cells was significantly inhibited by all treatments except IL-1Beta, with maximum effect observed with vitamin D(3) and PGE(2).\Question: Is the differential expression of osteoprotegerin ( OPG ) and receptor activator of nuclear factor kappaB ligand ( RANKL ) in human osteoarthritic subchondral bone osteoblasts an indicator of the metabolic state of these disease cells?

Output: OPG and RANKL levels, and consequently the OPG/RANKL ratio, differed according to human OA subchondral bone osteoblast classification; it is decreased in L and increased in H OA. These findings, in addition to those showing that L OA osteoblasts have a reduced subchondral bone mass and induce a higher level of osteoclast differentiation, strongly suggest that the metabolic state of the L OA osteoblasts favours bone resorption.


Input: Consider Input: Context: Growth-differentiation factor-15 (GDF-15) is emerging as an independent prognostic biomarker in patients with cardiovascular (CV) disease. Little is known about the pathophysiological basis for the close association of GDF-15 to future CV events. We hypothesized that GDF-15 is related to underlying CV pathologies.', 'To relate the levels of GDF-15 to indices of CV dysfunction and disease in elderly individuals, serum levels of GDF-15 were measured in 1004 subjects aged 70 years from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Carotid intima-media thickness and plaque burden, and left ventricular (LV) geometry and function were assessed by ultrasound. Endothelial function was evaluated in forearm resistance vessels and in the brachial artery by venous occlusion plethysmography and ultrasound imaging, respectively. Elevated levels of GDF-15 were related to several CV risk factors (male gender, current smoking, body mass index, waist circumference, diabetes, fasting glucose, triglycerides, and low HDL cholesterol). After adjustment for CV risk factors, increased levels of GDF-15 were associated with reduced endothelium-dependent vasodilation in resistance vessels, plaque burden, LV mass and concentric LV hypertrophy, reduced LV ejection fraction, and clinical manifestations of coronary artery disease and heart failure.\Question: Is growth-differentiation factor-15 an independent marker of cardiovascular dysfunction and disease in the elderly : results from the Prospective Investigation of the Vasculature in Uppsala Seniors ( PIVUS ) Study?


Output: GDF-15 carries information on CV dysfunction and disease that is not captured by traditional CV risk factors in elderly individuals.