Overexpression of human thioredoxin in transgenic mice controls oxidative stress and life span

Transgenic (Tg) mice overexpressing human thioredoxin (TRX), a small redox-active protein, were produced to investigate the role of the protein in a variety of stresses. Bone marrow cells from TRX-Tg mice were more resistant to ultraviolet C-induced cytocide compared with those from wild type (WT) C57BL/6 mice. TRX-Tg mice exhibited extended median and maximum life spans compared with WT mice. Telomerase activity in spleen tissues in TRX-Tg mice was higher than that in WT mice. These results suggest that overexpression of TRX results in resistance against oxidative stress and a possible extension of life span without apparent abnormality in mammals.     

Role of prostaglandin E receptor subtypes in gastroduodenal HCO3- secretion

Gastroduodenal HCO3- secretion is a key process that aids in preventing acid-peptic injury. Endogenous prostaglandins (PGs) play a particularly important role in the local control of this secretion. The secretion of HCO3- in both the stomach and duodenum was increased in response to PGE2 as well as mucosal acidification, the latter occurring with concomitant enhancement of mucosal PG generation. These HCO3- responses in the duodenum were markedly reduced by prior administration of the EP4 antagonist in rats, and profoundly decreased in the animals lacking EP3 receptors but not EP1 receptors. In contrast, gastric HCO3- responses induced by PGE2 and mucosal acidification were prevented by the EP1 antagonist and disappeared in EP1, but not EP3-knockout mice. Consistent with these findings, duodenal HCO3- secretion was stimulated by both EP3 and EP4 agonists but not EP1 or EP2 agonists, while gastric HCO3- secretion was increased by the EP1 agonist but not EP2, EP3 or EP4 agonists. In addition, the HCO3- stimulatory action of sulprostone (EP1/EP3 agonist) in the stomach was inhibited by the Ca2+ antagonist verapamil but not affected by IBMX, the inhibitor of phosphodiesterase, while that in the duodenum was inhibited by verapamil and enhanced by IBMX. Forskolin, the stimulator of adenylate cyclase, increased HCO3- secretion in the duodenum but not the stomach. Thus, the HCO3- stimulatory action of PGE2 in the duodenum is mediated by both EP3 and EP4 receptors being coupled intracellularly with both Ca2+ and cAMP, while that in the stomach is mediated by EP1 receptors, coupled with Ca2+.     

Otx1 function overlaps with Otx2 in development of mouse forebrain and midbrain

Background: We previously reported that the homozygous mutation of Otx2 gene, a mouse cognate of the Drosophila head gap gene orthodenticle , causes failure in the development of the rostral head anterior to rhombomere 3, which may correspond to earlier Otx2 expression in cells destined for the anterior mesoendoderm. At the same time, the Otx2 heterozygous mutation displayed a phenotype characterized as otocephaly, probably related to expression in the anterior neuroectoderm at the subsequent pharyngula stage. Defects were characteristic in the most anterior and posterior regions of Otx2 expression where Otx1 , another mouse cognate of orthodenticle , is not or weakly expressed. They were not found in the region where Otx1 is expressed.
Results: In the present work, Otx1 null mutant mice were generated by gene targeting in embryonic stem cells. No defects were apparent in the regionalization of the early embryonic rostral brain. The newborn brain defects were subtle and most likely related to later Otx1 -unique expression. Otx1 and Otx2 double heterozygous mutant brains, however, exhibited marked defects throughout the fore- and midbrains, where defects were not apparent with a single mutation alone.
Conclusions: Otx1 and Otx2 play synergistic roles in the development of the forebrain and midbrain where both genes are expressed.     

Myoglobinuria due to enzyme abnormalities in glycolytic pathway--especially lactate dehydrogenase M subunit deficiency]

Glycolysis is an important energy productive system. Enzyme abnormalities the in glycolytic pathway, which cause myoglobinuria, are deficiencies of phosphofructokinase, phosphoglycerate kinase, phosphoglycerate mutase, and lactate dehydrogenase (LDH). Common symptoms of these enzyme abnormalities are muscle cramp, muscle pain, and rhabdomyolysis after strenuous exercise. Acute renal failure owing to myoglobinuria is the most noteworthy symptom. In daily life, symptoms are rarely observed and prognosis is usually good. Correct and fast diagnosis of such latent symptomatic disorders is important to prevent a turn for the worse of these symptoms. LDH M subunit deficiency was first discovered by urinary discoloration and a discrepancy of laboratory data. Since then, only four cases have been reported in the Japanese population. The response to ischemic forearm work is characteristic (an increase of venous lactate concentration after ischemic work is not observed and a marked increase of venous pyruvate is found). The increase of pyruvate concentration is specific in LDH-M subunit deficiency, and is not observed in other abnormalities of the glycolytic pathway. Glycolysis was markedly retarded in the patient's muscle in the glyceraldehyde 3-phosphate dehydrogenase (GA3PD) step, possibly due to the impaired reoxidation of NADH produced by GA3PD activity. Then, the excess NADH is reoxidized by alpha-glycerophosphate dehydrogenase and triose phosphates are drained to alpha-glycerophosphate and glycerol. Therefore ATP production is significantly impaired and muscle tissue is damaged. A genetical study revealed a deletion of 20 base-pairs in exon 6 in LDH-M subunit deficiency. This mutation results in a frame-shift translation and premature termination.     

Treatment with cathepsin L inhibitor potentiates Th2-type immune response in Leishmania major-infected BALB/c mice

Prior to the activation of CD4 (+) T cells, exogenous proteins must be digested by endo/lysosomal enzymes in antigen-presenting cells (APC) to produce antigenic peptides that are able to be presented on class II molecules of the MHC. Studies described here inspect the functional significance of cathepsin L inhibition for antigen processing and T (h) 1/T (h) 2 differentiation in experimental leishmaniasis. We first demonstrated using in vitro systems that cathepsin L is one of the candidate endo/lysosomal enzymes in processing of soluble Leishmania antigen (SLA) and that its specific inhibitor, CLIK148, modulated the processing of SLA. BALB/c mice are known to be susceptible to infection with Leishmania major. Interestingly, treatment of BALB/c mice with CLIK148 exacerbated the infection by enhancing the development of SLA-specific T (h) 2-type response such as production of IL-4 and generation of T (h) 2-dependent specific IgE/IgG1 antibodies. Moreover, addition of CLIK148 in incubation of a SLA-specific CD4 (+) T cell line with APC up-regulated the production of IL-4. However, CLIK148 did not exert any direct influence on the function of T cells themselves. Taken together, these findings suggest that treatment of host mice with CLIK148 affects the processing of SLA in APC, resulting in the potentiation of T (h) 2-type immune responses and thus leading to exacerbation of the infection. Furthermore, endo/lysosomal cathepsin L was found to be functionally distinct from previously described cathepsins B and D.