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CDK5 and its activator P35 in normal pituitary and in pituitary adenomas: relationship to VEGF expression.

Xie W, Wang H, He Y, Li D, Gong L, Zhang Y - Int. J. Biol. Sci. (2014)

Bottom Line: The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35).Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis.Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

View Article: PubMed Central - PubMed

Affiliation: Beijing Neurosurgical Institute, Beijing Tiantan Hospital Affiliated to Capital Medical University, Beijing 100050, China.

ABSTRACT
Pituitary tumors are monoclonal adenomas that account for about 10-15% of intracranial tumors. Cyclin-dependent kinase 5 (CDK5) regulates the activities of various proteins and cellular processes in the nervous system, but its potential roles in pituitary adenomas are poorly understood. The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35). Here, we show that functional CDK5, associated with p35, is present in normal human pituitary and in pituitary tumors. Furthermore, p35 mRNA and protein levels were higher in pituitary adenomas than in the normal glands, suggesting that CDK5 activity might be upregulated in pituitary tumors. Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis. Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

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A, Presence of p35 in normal human pituitary. Immunofluorescence double-staining for p35 (green) and nuclear (blue) was performed; B, Presence of P35 in pituitary adenomas. Immunofluorescence double-staining for P35 (green) and nuclear (blue) was performed; C, Colocalization of p35 and and VEGF in the normal human pituitary gland. Immunofluorescence double-staining for p35 (green) and VEGF (red) was performed. Colocalization of both is indicated by filled arrowheads. Data are representative of at least three different human adult pituitary samples and at least three independent experiments. Scale bar, 20μm.
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Figure 2: A, Presence of p35 in normal human pituitary. Immunofluorescence double-staining for p35 (green) and nuclear (blue) was performed; B, Presence of P35 in pituitary adenomas. Immunofluorescence double-staining for P35 (green) and nuclear (blue) was performed; C, Colocalization of p35 and and VEGF in the normal human pituitary gland. Immunofluorescence double-staining for p35 (green) and VEGF (red) was performed. Colocalization of both is indicated by filled arrowheads. Data are representative of at least three different human adult pituitary samples and at least three independent experiments. Scale bar, 20μm.

Mentions: We investigated and confirmed CDK5 and p35 protein expression in normal human pituitary glands obtained from autopsies of eight individuals. The anti-p35 and anti-CDK5 antibodies gave single bands in western blot analysis (Fig.1A). The p35/GAPDH ratio was used as a measure of p35 protein levels (Fig.1B). In addition, we determined p35 distribution in normal human pituitary by immunofluorescent staining. The protein was detected in about 10-20% of the pituitary cells, and the immunofluorescent signal was granular and found in the cytoplasm (Fig 2A). To further identify whether p35 and VEGF were co-localization in human normal pituitary, we performed double immunofluorescent staining of p35 and VEGF. The results showed that some VEGF (red) was partially located in p35 (green)-positive cells (Fig. 2C). The specificity of the p35 antibody was confirmed by observing the lack of immunofluorescent signal when the samples were incubated with a mixture of antibody and a blocking p35 peptide (data not shown). Our results indicated that both CDK5 and its activator p35 were expressed in normal human pituitary and suggested that p35 and VEGF were co-localizated in human normal pituitary.


CDK5 and its activator P35 in normal pituitary and in pituitary adenomas: relationship to VEGF expression.

Xie W, Wang H, He Y, Li D, Gong L, Zhang Y - Int. J. Biol. Sci. (2014)

A, Presence of p35 in normal human pituitary. Immunofluorescence double-staining for p35 (green) and nuclear (blue) was performed; B, Presence of P35 in pituitary adenomas. Immunofluorescence double-staining for P35 (green) and nuclear (blue) was performed; C, Colocalization of p35 and and VEGF in the normal human pituitary gland. Immunofluorescence double-staining for p35 (green) and VEGF (red) was performed. Colocalization of both is indicated by filled arrowheads. Data are representative of at least three different human adult pituitary samples and at least three independent experiments. Scale bar, 20μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927131&req=5

Figure 2: A, Presence of p35 in normal human pituitary. Immunofluorescence double-staining for p35 (green) and nuclear (blue) was performed; B, Presence of P35 in pituitary adenomas. Immunofluorescence double-staining for P35 (green) and nuclear (blue) was performed; C, Colocalization of p35 and and VEGF in the normal human pituitary gland. Immunofluorescence double-staining for p35 (green) and VEGF (red) was performed. Colocalization of both is indicated by filled arrowheads. Data are representative of at least three different human adult pituitary samples and at least three independent experiments. Scale bar, 20μm.
Mentions: We investigated and confirmed CDK5 and p35 protein expression in normal human pituitary glands obtained from autopsies of eight individuals. The anti-p35 and anti-CDK5 antibodies gave single bands in western blot analysis (Fig.1A). The p35/GAPDH ratio was used as a measure of p35 protein levels (Fig.1B). In addition, we determined p35 distribution in normal human pituitary by immunofluorescent staining. The protein was detected in about 10-20% of the pituitary cells, and the immunofluorescent signal was granular and found in the cytoplasm (Fig 2A). To further identify whether p35 and VEGF were co-localization in human normal pituitary, we performed double immunofluorescent staining of p35 and VEGF. The results showed that some VEGF (red) was partially located in p35 (green)-positive cells (Fig. 2C). The specificity of the p35 antibody was confirmed by observing the lack of immunofluorescent signal when the samples were incubated with a mixture of antibody and a blocking p35 peptide (data not shown). Our results indicated that both CDK5 and its activator p35 were expressed in normal human pituitary and suggested that p35 and VEGF were co-localizated in human normal pituitary.

Bottom Line: The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35).Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis.Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

View Article: PubMed Central - PubMed

Affiliation: Beijing Neurosurgical Institute, Beijing Tiantan Hospital Affiliated to Capital Medical University, Beijing 100050, China.

ABSTRACT
Pituitary tumors are monoclonal adenomas that account for about 10-15% of intracranial tumors. Cyclin-dependent kinase 5 (CDK5) regulates the activities of various proteins and cellular processes in the nervous system, but its potential roles in pituitary adenomas are poorly understood. The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35). Here, we show that functional CDK5, associated with p35, is present in normal human pituitary and in pituitary tumors. Furthermore, p35 mRNA and protein levels were higher in pituitary adenomas than in the normal glands, suggesting that CDK5 activity might be upregulated in pituitary tumors. Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis. Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

Show MeSH
Related in: MedlinePlus