Dipeptide uptake: A novel marker for testicular and ovarian macrophages

Otto, Christiane; Bauer, Karl

doi:10.1002/(sici)1097-0185(199608)245:4<662::aid-ar6>3.0.co;2-q

Cited by 9 publications

(3 citation statements)

References 20 publications

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“…This was particularly interesting since like FS cells in the anterior pituitary, resident macrophages of certain tissues also seem to be implicated in the paracrine regulation of hormone secretion. With ß-Ala-Lys-N e -AMCA as substrate, we observed a rapid accumulation of the reporter molecule in testicular and ovarian macrophages by a transport system that exhibits the biochemical characteristics of the astroglial dipeptide transporter PepT2 (31). ß-Ala-Lys-N e -AMCA is not taken up by blood monocytes which corroborates the view that these tissue macrophages play a pivotal role in the paracrine regulation of steroidogenesis and may even constitute a link between the endocrine and the immune system (for review see Ref.…”

Section: Dipeptide Uptake By Testicular and Ovarian Macrophagessupporting

confidence: 80%

Carnosine and Homocarnosine, the Forgotten, Enigmatic Peptides of the Brain

Bauer¹

2005

Neurochem Res

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Carnosine (beta-alanyl-histidine) and homocarnosine (gamma-aminobutyryl-histidine) are major constituents of excitable tissues, brain and skeletal muscles, but their physiological functions are yet unknown. Using primary cell culture systems, synthesis and uptake of carnosine exclusively by glial cells could be demonstrated. Uptake of carnosine was found to be mediated by a high affinity, energy-dependent dipeptide transport system, subsequently identified as the peptide transporter PepT2. With the synthesis of beta-Ala-Lys-Nepsilon-AMCA as a fluorescent reporter molecule, accumulation of this dipeptide derivative could be monitored under viable conditions not only in astroglia cells but also in folliculostellate cells of the anterior pituitary and in gonadal resident macrophages. This reporter dipeptide provided a most valuable tool to identify an intrapituitary communication system by tracing folliculostellate cells in acute slice preparation. Moreover, this substance could also be used to prepare pituitary cell cultures enriched with or depleted of folliculostellate cells that are needed for further studies.

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Section: Dipeptide Uptake By Testicular and Ovarian Macrophagessupporting

confidence: 80%

Carnosine and Homocarnosine, the Forgotten, Enigmatic Peptides of the Brain

Bauer¹

2005

Neurochem Res

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“…The uptake experiment was performed according to previous reports. − Cells were seeded in a 24-well plate one day before the experiment. After aspirating the culture medium, cells were washed once with the HBSS buffer.…”

Section: Methodsmentioning

confidence: 99%

Expression Profile and Functional Activity of Peptide Transporters in Prostate Cancer Cells

2012

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Peptide transporters are expressed predominantly in intestinal and renal epithelial cells. The functional expression of peptide transporters is also identified in other types of tissues, such as glia cells, macrophages, and the epithelia of the bile duct, the lungs and the mammary glands. However, their presence and role are poorly understood in carcinomas. We explored the expression profile and functional activity of peptide transporters in the prostate cancer cell lines LNCaP, PC-3 and DU145. Quantitative Real Time PCR (qRT-PCR) and Western blot were used to evaluate the expression profile of peptide transporter 1 (PEPT1), peptide transporter 2 (PEPT2), peptide histidine transporter 1 (PHT1) and peptide histidine transporter 2 (PHT2) in these cells. LNCaP expresses high levels of PEPT2 and PHT1, while PC-3 demonstrates strong expression of PEPT1 and PHT1. DU145 shows only weak expression of PEPT1 and PHT1. Functional activities were studied in these cell lines using radiolabeled Glycylsarcosine ([3H]Gly-Sar) and L-Histidine ([3H]L-Histidine). The uptake of [3H]Gly-Sar and [3H]L-Histidine was time- and pH-dependent. A kinetic study showed that the uptake of Gly-Sar and L-Histidine is saturable over the tested concentration range. The binding affinity (Km) and the maximal velocity (Vmax) exhibited in the three cell lines were consistent with the expression profiles we observed in qPCR and Western blot analysis. A competitive inhibition study revealed that peptide transporters in prostate cancer cells exhibited broad substrate specificity with a preference for hydrophobic dipeptides, such as Leu-Leu. Fluorescence microscopy revealed that the fluorescent dipeptide probe D-Ala-Lys-AMCA (a substrate of peptide transporters) specifically accumulated in the cytoplasm of LNCaP and PC-3, but not DU145 cells. Inhibiting the peptide transporter activity by Gly-Sar suppressed the growth of LNCaP and PC-3 cells. Our study indicated that PC-3 cells can be established as a new cell culture model for PEPT1 study, and LNCaP can be used as a model for PEPT2 study. Moreover, our results suggested that peptide transporters are over-expressed in prostate cancer cells and can be adopted as a promising target for tumor-specific drug delivery.

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“…The tissues were incubated with MEM-21011 containing 25 µM D-Ala-L-Lys-N-epsilon-7-amino-4-methylcoumarin-3-acetic acid (D-Ala-L-Lys-AMCA) which has previously been shown to be a specific substrate. [27][28][29][30] For competitive inhibition studies 25 µM D-Ala-L-Lys-AMCA plus 1 mM of the unlabelled competitive dipeptide glycyl-L-glutamine, 1 mM unlabelled cefadroxil or 1 mM unlabelled captopril was used. Controls included the omission of the different labelled or unlabelled substrates, incubations performed at 4°C, or by adding the transport inhibitor diethylpyrocarbonate.…”

Section: Immunohistochemistrymentioning

confidence: 99%

Distribution and function of the peptide transporter PEPT2 in normal and cystic fibrosis human lung

Groneberg

Eynott²,

Döring³

et al. 2002

Thorax

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Background: Aerosol administration of peptide based drugs has an important role in the treatment of various pulmonary and systemic diseases. The characterisation of pulmonary peptide transport pathways can lead to new strategies in aerosol drug treatment. Methods: Immunohistochemistry and ex vivo uptake studies were established to assess the distribution and activity of the β-lactam transporting high affinity proton coupled peptide transporter PEPT2 in normal and cystic fibrosis human airway tissue. Results: PEPT2 immunoreactivity in normal human airways was localised to cells of the tracheal and bronchial epithelium and the endothelium of small vessels. In peripheral lung immunoreactivity was restricted to type II pneumocytes. In sections of cystic fibrosis lung a similar pattern of distribution was obtained with signals localised to endothelial cells, airway epithelium, and type II pneumocytes. Functional ex vivo uptake studies with fresh lung specimens led to an uptake of the fluorophore conjugated dipeptide derivative D-Ala-L-Lys-AMCA into bronchial epithelial cells and type II pneumocytes. This uptake was competitively inhibited by dipeptides and cephalosporins but not ACE inhibitors, indicating a substrate specificity as described for PEPT2. Conclusions: These findings provide evidence for the expression and function of the peptide transporter PEPT2 in the normal and cystic fibrosis human respiratory tract and suggest that PEPT2 is likely to play a role in the transport of pulmonary peptides and peptidomimetics.

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Dipeptide uptake: A novel marker for testicular and ovarian macrophages

Cited by 9 publications

References 20 publications

Carnosine and Homocarnosine, the Forgotten, Enigmatic Peptides of the Brain

Carnosine and Homocarnosine, the Forgotten, Enigmatic Peptides of the Brain

Expression Profile and Functional Activity of Peptide Transporters in Prostate Cancer Cells

Distribution and function of the peptide transporter PEPT2 in normal and cystic fibrosis human lung

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