The increase of electrophoretic mobility and alkaline phosphatase activity are parallel events during B-cell maturation

Tissue-Nonspecific Alkaline Phosphatase, a Possible Mediator of Cell Maturation: Towards a New Paradigm

Alkaline phosphatase (ALP) is a ubiquitous membrane-bound glycoprotein capable of providing inorganic phosphate by catalyzing the hydrolysis of organic phosphate esters, or removing inorganic pyrophosphate that inhibits calcification. In humans, four forms of ALP cDNA have been cloned, among which tissue-nonspecific ALP (TNSALP) (TNSALP) is widely distributed in the liver, bone, and kidney, making it an important marker in clinical and basic research. Interestingly, TNSALP is highly expressed in juvenile cells, such as pluripotent stem cells (i.e., embryonic stem cells and induced pluripotent stem cells (iPSCs)) and somatic stem cells (i.e., neuronal stem cells and bone marrow mesenchymal stem cells). Hypophosphatasia is a genetic disorder causing defects in bone and tooth development as well as neurogenesis. Mutations in the gene coding for TNSALP are thought to be responsible for the abnormalities, suggesting the essential role of TNSALP in these events. Moreover, a reverse-genetics-based study using mice revealed that TNSALP is important in bone and tooth development as well as neurogenesis. However, little is known about the role of TNSALP in the maintenance and differentiation of juvenile cells. Recently, it was reported that cells enriched with TNSALP are more easily reprogrammed into iPSCs than those with less TNSALP. Furthermore, in bone marrow stem cells, ALP could function as a "signal regulator" deciding the fate of these cells. In this review, we summarize the properties of ALP and the background of ALP gene analysis and its manipulation, with a special focus on the potential role of TNSALP in the generation (and possibly maintenance) of juvenile cells.

Systemic inhibition of tissue-nonspecific alkaline phosphatase alters the brain-immune axis in experimental sepsis

Tissue-nonspecific alkaline phosphatase (TNAP) is a ubiquitous enzyme present in many cells and tissues, including the central nervous system. Yet its functions at the brain-immune axis remain unclear. The goal of this study was to use a novel small molecular inhibitor of TNAP, SBI-425, to interrogate the function of TNAP in neuroimmune disorders. Following intraperitoneal (IP) administration of SBI-425, mass spectrometry analysis revealed that the SBI-425 does not cross the blood-brain barrier (BBB) in healthy mice. To elucidate the role of TNAP at the brain-immune axis, mice were subjected to experimental sepsis and received either vehicle or SBI-425 (25 mg/kg, IP) daily for 7 days. While SBI-425 administration did not affect clinical severity outcomes, we found that SBI-425 administration suppressed CD4 + Foxp3+ CD25- and CD8 + Foxp3+ CD25- splenocyte T-cell populations compared to controls. Further evaluation of SBI-425's effects in the brain revealed that TNAP activity was suppressed in the brain parenchyma of SBI-425-treated mice compared to controls. When primary brain endothelial cells were treated with a proinflammatory stimulus the addition of SBI-425 treatment potentiated the loss of barrier function in BBB endothelial cells. To further demonstrate a protective role for TNAP at endothelial barriers within this axis, transgenic mice with a conditional overexpression of TNAP were subjected to experimental sepsis and found to have increased survival and decreased clinical severity scores compared to controls. Taken together, these results demonstrate a novel role for TNAP activity in shaping the dynamic interactions within the brain-immune axis.

Preparative enrichment of human tissue cells capable to change a site of growth in vitro or in vivo - Recent developments

Human cells are heterogeneous in regard to their biochemical features and functions. Detailed knowledge about each single cell type is important to understand the whole organism. In order to get a deeper insight in the concert of life, it has to be considered that cell populations such as thyroid cells, epithelial breast cells, endothelial cells, or chondrocytes are heterogeneous in regard to function, RNA expression patterns and protein content. This is true for normal cells and even more relevant for cancer cells. A number of sophisticated methods were developed to enrich cohorts of cells generally belonging to a defined type but outstanding by distinct characteristics, which can be detected by microscopic, proteomic or genomic methods. There is a great interest to investigate human cells, which are able to change their site of growth within the human body leaving an original site, migrating through vessels and reentering another site. In this review experiments are summarized showing that the application of microgravity-exposure of human cells and cell electrophoresis enable a characterization of cells, which leave a site of growth to enter another one. Biochemical features of separated subpopulations are described and their usefulness for deeper investigation is highlighted.

Advances in cell separation: recent developments in counterflow centrifugal elutriation and continuous flow cell separation

Cell separation by counterflow centrifugal elutriation (CCE) or free flow electrophoresis (FFE) is performed at lower frequency than cell cloning and antibody-dependent, magnetic or fluorescence-activated cell sorting. Nevertheless, numerous recent publications confirmed that these physical cell separation methods that do not include cell labeling or cell transformation steps, may be most useful for some applications. CCE and FFE have proved to be valuable tools, if homogeneous populations of normal healthy untransformed cells are required for answering scientific questions or for clinical transplantation and cells cannot be labeled by antibodies, because suitable antibodies are not available or because antibody binding to a cell surface would induce the cell reaction which should be investigated on purified cells or because antibodies bound to the surface hamper the use of the isolated cells. In addition, the methods are helpful for studying the biological reasons for, or effects of, changes in cell size and cellular negative surface charge density. Although the value of the methods was confirmed in recent years by a considerable number of important scientific results, activities to further develop and improve the instruments have, unfortunately, declined.

Cellular electrophoretic mobility data: a first approach to a database

Cellular electrophoretic mobility values of 288 types of eucaryotic cells were collected from literature published worldwide by a series of authors during the past forty years and arranged in a list. This list contains well-known recent electrophoretic results and also data that cannot be found anymore with modern literature retrieval systems. It will be a valuable help for scientists trying to purify cell populations. In addition, it confirms the observation that most eucaryotic cells have very similar electrophoretic mobilities, ranging from 40% above to 50% below the electrophoretic mobility of human erythrocytes, and thus reinforces the suggestion that electrophoretic mobilities of eucaryotic cells are subjected to strong biological controls.

Sodium chloride in preparative free-flow cell electrophoresis: recent developments

Three buffer systems for free-flow electrophoresis have been designed, which proved useful for performing cell electrophoresis in the presence of 50 mM NaCl. Each system consists of one central cell suspension buffer with 50 mM NaCl, two margin buffers, and two electrode buffers. With the aid of a bromophenol blue/maxilon blue accumulation test the various buffers were adjusted to ensure a laminar flow and remain unchanged on their way through an electrophoresis chamber.

Sodium chloride in separation medium enhances cell compatibility of free flow electrophoresis

Free flow electrophoresis of cell suspensions in buffers containing sodium chloride was investigated using a modified procedure and the new apparatus Octopus PZE. The major methodical innovations are upward fluid flow, margin buffers flowing through the electrophoresis chamber at both sides of a central cell suspension buffer, adjacent to the electrode membranes, and a sample injection device which focuses the cells hydrodynamically to the middle of the chamber thickness. Mononuclear leukocytes, suspended in a buffer containing 35 mM NaCl, could be fractionated with the same accuracy as by conventional free flow electrophoresis, operated with a single NaCl-free chamber buffer. However, testing the vitality of separated cells with the help of the calcium indicator FURA2-AM clearly demonstrated the biological importance of the presence of a minimum amount of sodium chloride during cell electrophoresis. Only if at least 35 mM NaCl were present could an undisturbed cytosolic Ca2+ metabolism be maintained for the time of a free flow electrophoresis cell separation experiment.

Effect of anti-alkaline phosphatase monoclonal antibody on B lymphocyte function

Alkaline phosphatase (APase) is a glycosylphosphatidyl-inositol (GPI)-anchored protein appearing on the membranes of mitogen-stimulated B cells after progression into S phase of the cell cycle. Maximal APase expression occurs after peak proliferation and precedes maximal immunoglobulin (Ig) secretion. While APase is clearly an activation marker for mitogen-stimulated B cells, the physiologic role of APase in B cells has not been defined. Other GPI-anchored proteins have been assigned roles in transmembrane signaling since treatment with specific monoclonal antibodies (mAbs) can modulate and/or mimic the effect of mitogens or antigens. Thus, as an initial attempt to determine whether membrane APase (mAPase) plays a role in B cell activation, rat splenic B cells were treated with anti-APase specific mAb in the presence and absence of LPS plus dextran sulfate, known B cell mitogens. Anti-APase mAb alone did not induce proliferation or modulate mitogen-induced proliferation as measured by [3H]thymidine uptake and viable cell recoveries. However, the mAb augmented IgM secretion when used in a soluble form or cross-linked with anti-Ig. Both soluble and immobilized anti-APase mAb decreased the expression of APase activity by mitogen-stimulated B cells. Based upon these results we propose: (1) that transmembrane signaling may occur through mAPase as described for other GPI-anchored proteins such as Thy-1, CD55, CD59, CD24, CD73, Fc gamma III, Qa-2, Ly-6A/E and LFA-3, and (2) this signaling may be regulated by changes in protein phosphorylation caused by modulation of cellular phosphatases, specifically APase.

Linkage between monokine production and regulation of the negative surface charge density of human monocytes

The regulation of the negative surface charge density of human monocytes was investigated with the help of the synthetic glycolipid analogue BAY R 1005. This compound is incorporated into the outer membrane of isolated monocytes during 24 hours of incubation. After this time the electrophoretic mobility (EM) of monocytes is unchanged at 0.95 x 10(-4) (cm2 V-1 s-1) and remains unchanged even under conditions where non-treated monocytes increase their EM up to 1.1 x 10(-4) (cm2 V-1 s-1). In addition BAY R 1005 stops differentiation of monocytes to macrophages, it triggers monokine production and abolishes monocyte suppressor activity and spreading capability. The results show that BAY R 1005 affects intracellular features. In connection with earlier investigations of the regulation of the negative surface charge density of human monocytes (1,2) the study suggests that monokine production and maintenance of the EM of monocytes are linked.