Changes in cell adhesion and cell proliferation are associated with expression of tissue non-specific alkaline phosphatase

Abstract

Tissue non-specific alkaline phosphatase is a membrane-bound glycoprotein enzyme which is characterized by its phosphohydrolytic, protein phosphatase, and phosphotransferase activities. This enzyme is distributed virtually in all mammalian tissues, particularly during embryonic development. Its expression is stage-specific and can be demonstrated in the developing embryo as early as the 2-cell stage. It has been suggested that tissue non-specific alkaline phosphatase might play a role in tissue formation. In the study reported here, a gene-transfer approach was employed to investigate possible roles for this enzyme by inserting the cDNA for rat tissue non-specific alkaline phosphatase into CHO and LLC-PK1 cells. Permanently transfected cell-lines expressing varying levels of alkaline phosphatase were established. The data showed that functional enzyme was expressed in the transfected cells. Cell spreading and attachment were enhanced in transfected CHO cells expressing high levels of tissue non-specific alkaline phosphatase but not in the LLC-PK1 cells. Further, in CHO cells, proliferation was shown to be inversely proportional to the level of the tissue non-specific alkaline phosphatase expression. Homotypic cell association was demonstrated in both alkaline phosphatase-positive and alkaline phosphatase-negative cells in both CHO and LLC-PK1 cell-lines. Taken together, these findings suggest that in addition to a role in mineralization of bone, tissue non-specific alkaline phosphatase might also play a role in other cell activities, including those related to differentiation, such as cell-cell or cell-substrate interaction and proliferation.

Biochemical and proteomic investigation of bovine nasal secretion

“…The AP have been postulated to be involved in a range of other processes, including cell adhesion (Hui et al 1993), vitamin B transport (Rindi et al 1995), metastasis (Manara et al 2000), and cell signaling (Swarup et al 1981;Muller et al 1991). Recent studies of the biological function of AP have revealed that the enzyme has the ability to dephosphorylate LPS endotoxin from Gram-negative bacteria (Poelstra et al, 1997;Koyoma et al, 2002 andBeumer et al, 2003) reducing the toxic effects of LPS (Bates et al, 2007) and, in the intestine, can be induced by Resolvin E1, an anti-inflammatory derivative of omega-3 fatty acids (Campbell et al, 2010).…”

Changes of alkaline phosphatase activity in response to different stressors in planarian Dugesia japonica

“…This enzyme is involved in a variety of metabolic processes, such as bone mineralization, molecule permeability, cell growth and differentiation, osmoregulation, and regeneration (Whittaker et al 1990;Andracchi & Korte 1991;Hui et al 1993;Lovett et al 1994;Wright 1997;Hessle et al 2002;Pinoni et al 2005;Whyte 2010). The measurement of alkaline phosphatase activity is generally carried out in clinical and ecotoxicological studies (Moss 1992;Molina et al 2005;Albrecht et al .…”

Tissue Non-Specific Alkaline Phosphatase May Be a Function-Related Marker in Renal Proximal Tubular Epithelia and in Vascular Endothelia as It Is in Osteoblasts

“…To regenerate LLC-PK 1 and Py-4-1 cell lines that express high levels o f TN-AP, the TN-AP expression vector pSVAP containing a rat TN-AP cD NA under the control o f SV40 early promoter was stably co-transfected into LLC-PK 1 and Py-4-1 cell lines together with an antibiotic resistance gene expression plasmid pSVneo as described previously [8,16]. Non-AP trans fected (AP-ve) LLC-PK 1 and Py-4-1 cell lines were generated by transfecting with pSVneo only.…”

“…Lines Expressing an Elevated Level o f TN-AP LLC-PK1 cells are proximal tubular epithelia-like cells characterized by density growth inhibition, active transport o f salts and glucose [ 14], and very' low endog enous AP activity [8,16]. Py-4-l cells are vascular endothelia-like cells, characterized by pseudopodia A lkaline P h o sp h a ta se as F u n c tio n -R e la te d M ark er processes, expression o f von Willebrand factor and active uptake o f Ac-LDL [15].…”

“…Being aware of the above and TN-AP as a multifunctional enzyme in vitro, we hypothesize that high TN-AP expression is also a function-related marker in renal proxi mal tubular epithelia and vascular endothelia. To test this hypothesis, a TN-AP gene was introduced and expressed under the control of a SV40 early promoter, into a well-character ized renal proximal tubular epithelia-like cell line (LLC-PK1) [14] and a vascular endothelia-like cell line (Py-4-1) [15] using a stable gene co-transfection technique [8,16]. The effect of TN-AP expression on cellular activi ties was then examined by comparison with non-AP gene-transfected cells.…”