Figure 4.

Immortalized human CLL cells take up arginine also mainly via CAT-1. (A) Arginine transporter mRNA expression was quantified by qRT-PCR in HG3, MEC1, and JVM-2 CLL cells in relation to beta 2-Mikroglobulin (B2M) (means ± SD, n = 3). (B) Protein expression of CAT-1, y⁺LAT1, and y⁺LAT2 was determined in HG3, MEC1, and JVM-2 cells by Western Blot. GAPDH served as loading control. One representative Western Blot of in total 3 independent experiments is shown. (C) Uptake of 100 μM [³H]arginine (10 μCi/ml) in HG3 CLL cells was assessed over 5, 30, 60, and 120 s. Arginine uptake is depicted in pmol/10⁶ cells as means ± SD (n = 3), shown is one representative of 3 cell batches. (D–F) Uptake of 100 μM [³H]arginine (10 μCi/ml) was determined in HG3 cells over 30 s in the absence or the presence of (D) sodium (n = 15), (E) 200 μM NEM (n = 12) or (F) 200 μM NEM and 1 mM leucine (n = 9). Arginine uptake in HG3 cells in the presence of sodium and in the absence of any inhibitor was set as 100% and means ± SD values are depicted. Statistical calculations were performed by t-test.