Mechanism of the acidosis induced adaptation in renal gamma-glutamyltransferase

Acidosis induces an adaptation in renal γ-glutamyltransferase activity. The mechanism responsible for this adaptation was studied in isolated kidneys from control and chronically acidotic rats perfused with either γ-glutamyl-p-nitroanilide or D-glutamine. The results clearly establish that acidosis increased the utilization of both γ-glutamyl donors and that the adaptation occurs on both the luminal (urine) and antiluminal (blood) border of tubule cells. Acidotic rat kidneys exhibited an apparent Vmax for γ-glutamyl-p-nitroanilide similar to that of the control while the apparent K_m was significantly reduced consistent with an increased affinity of the enzyme for the substrate in acidosis.     

Toxoplasma gondii infection enhances testicular steroidogenesis in rats

The protozoan parasite Toxoplasma gondii enhances the sexual attractiveness of infected male rats and attenuates the innate fear of cat odour in infected individuals. These behavioural changes plausibly lead to greater transmission of parasites through sexual and trophic routes, respectively. Testosterone, a testicular steroid, is known to reduce fear and enhance sexual attractiveness in males. Here, we show that Toxoplasma gondii infection enhances expression of genes involved in facilitating synthesis of testosterone, resulting in greater testicular testosterone production in male rats. In several species, testosterone mediates trade‐offs between sexually selected traits and life history decisions. Augmentation of testosterone synthesis by Toxoplasma gondii suggests that parasites may manipulate these trade‐offs in rats.     

4-1BB (CD137), an inducible costimulatory receptor,as a specific target for cancer therapy

Although considerable progress has been made in understanding how tumors evade immune surveillance, measures to counter the same have not kept pace with the advances made in designing effective strategies. 4-1BB (CD137; TNFRS9), an activation-induced costimulatory molecule, is an important regulator of immune responses. Targeting 4-1BB or its natural ligand 4-1BB ligand (4-1BBL) has important implications in many clinical conditions, including cancer. In-depth analysis revealed that 4-1BB-mediated anti-cancer effects are based on its ability to induce activation of cytotoxic T lymphocytes (CTL), and among others, high amounts of IFN-γ. In this review, we will discuss the various aspects of 4-1BB-mediated anti-tumor responses, the basis of such responses, and future directions. [BMB Reports 2014; 47(3): 122-129]