Human mercaptolactate-cysteine disulfiduria (MCDU) was first recognized and reported in 1968. Most cases of MCDU are associated with mental retardation, while the pathogenesis remains unknown. To investigate it, we generated homozygous 3-mercaptopyruvate sulfurtransferase (MST: EC 2.8.1.2) knockout (KO) mice using C57BL/6 embryonic stem cells as an animal model. The MST-KO mice showed significantly increased anxiety-like behaviors with an increase in serotonin level in the prefrontal cortex (PFC), but not with abnormal morphological changes in the brain. MCDU can be caused by loss in the functional diversity of MST; first, MST functions as an antioxidant protein. MST possessing 2 redox-sensing molecular switches maintains cellular redox homeostasis. Second, MST can produce H2S (or HS−). Third, MST can also produce SOx. It is concluded that behavioral abnormality in MST-KO mice is caused by MST function defects such as an antioxidant insufficiency or a new transducer, H2S (or HS−) and/or SOx deficiency.

Matrix metalloproteinases (MMPs) are endopeptidases that degrade extracellular matrix and involved in ischemic organ injuries. The present study was designed to determine the role of MMP-2 in the development of ischemic acute kidney injury (AKI). AKI was induced in MMP-2 wild-type (MMP-2 þ / þ ) mice by 30, 60, 90, and 120 min renal ischemia and reperfusion. Renal histology, expression and activity of MMP-2 and MMP-9, and renal function were examined during the development of AKI. AKI was also induced in MMP-2-deficient (MMP-2 À/À ) mice and MMP-2 þ / þ mice treated with inhibitor of MMPs (minocycline and synthetic peptide MMP inhibitor). In MMP-2 þ / þ mice, MMP-2 and MMP-9 activities increased significantly at 2 to 24 h, peaked at 6 h, after reperfusion. Immunohistochemical analysis identified MMP-2 in the interstitium around tubules and peritubular capillaries in the outer medulla. Acute tubular injury (ATI), including apoptosis and necrosis, was evident in the outer medulla at 24 h, along with renal dysfunction. As ischemia period increases, MMP-2 and MMP-9 activities at 6 h and severity of AKI at 24 h increased depending on the duration of ischemia between 30 and 120 min. However, the kidneys of MMP-2 À/À mice showed minimal ATI; serum creatinine 24 h after reperfusion was significantly low in these mice. Inhibitors of MMPs reduced ATI and improved renal dysfunction at 24 h. We conclude that MMPs, especially MMP-2 have a pathogenic role in ischemiareperfusion AKI, and that inhibitors of MMPs can protect against ischemic AKI. KEYWORDS: acute kidney injury; acute tubular injury; ischemia/reperfusion; MMP-2; MMP-9; MMP inhibitor Ischemia-reperfusion acute kidney injury (AKI) remains a major cause of morbidity and mortality.1-5 The pathophysiology of AKI is complex; the initial ischemia and reperfusion events rapidly lead to energy loss, which ultimately triggers a wide and intricately linked cascade of tubular epithelial cell death pathways. Over the past decade, various molecular mechanisms have been implicated, including activation of Ca 2 þ -dependent proteases or other enzymes, oxidative stress, and even programmed cell death signals, such as apoptosis. [6][7][8] In addition to these primarily intracellular events, evidence for the importance of intercellular signaling is beginning to emerge, all cells in the renal tubular and microvasculature are also affected, not just tubular epithelial cells.6-10 Renal tubulovascular perturbations in AKI lead to tubular damage, back leak, obstructive cast formation, leukocyte infiltration, and altered renal microvascular function that contribute to the development of AKI over hours or days after ischemia-reperfusion.Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteases responsible for extracellular matrix turnover, as well as degradation of bioactive proteins. 11,12 This family includes collagenases, gelatinases, stromelysins, and membranetype MMPs. Recently, MMPs, especially gelatinases (MMP-2 and MMP-9) have been demonstrated to have major roles i...

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Novel methotrexate (MTX) derivatives bearing dihydro-2H-1,4-benzothiazine or dihydro-2H-1,4-benzoxazine were synthesized and tested for in vitro antiproliferative activities against human synovial cells (hSC) and human peripheral blood mononuclear cells (hPBMC) obtained from patients with rheumatoid arthritis and healthy volunteers, respectively. In vivo antiarthritic activities of these derivatives were also evaluated in a rat adjuvant arthritis model. N-[[4-[(2,4-Diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzothiazin-7-yl]carbonyl]-L-glutamic acid (3c) exhibited more potent antiproliferative activities in hSC and hPBMC than MTX in vitro. Antiproliferative activities of N-[[4-[(2,4-diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzoxazin-7-yl]carbonyl]-L-homoglutamic acid (3b) and N-[[4-[(2,4-diaminopteridin-6-yl)methyl]-3,4-dihydro-2H-1, 4-benzothiazin-7-yl]carbonyl]-L-homoglutamic acid (3d) (MX-68) were comparable to that of MTX in these in vitro assays. Compounds 3b,d (MX-68) significantly suppressed progression of the adjuvant arthritis in a dose-dependent manner ranging from 0.5 to 2.5 mg/kg (po). In addition, 3d (MX-68) completely suppressed this progression at the dose of 2.5 mg/kg (po). Importantly, 3d (MX-68) having benzothiazine and homoglutamate, as expected, did not undergo polyglutamation, a process which may be responsible for the associated side effects of MTX. These results suggest that 3d (MX-68) is a potent and safe candidate antirheumatic agent, absent of the side effects of MTX.

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