摘要：

Investigate the apoptotic pathway induced by the muramyldipeptide (MDP) (smallest biologically active component of bacterialcell wall peptidoglycan that can induce anterior uveitis andconjunctivitis in rabbits); mediated via interaction of MDP/surfacecalreticulin/glucocorticosteroid receptor complex in rabbitkidney (RK) cells. PolyA mRNA was isolatedfrom control and MDP treated RKcells and the apoptoticgenes expressed were determined in human and mouse apoptosisgene expression arrays (rabbit apoptosis gene expression arraysare not available). DNA ladder and caspase 3 assays were performed.Caspase 3 activity and apoptotic DNA was detected inRKcell cultures within 4 hr of MDP treatment. Four geneswere induced in RKcells by MDP treatment; c myc(inhibits NFß and promotes TNF induced releaseof cytochrome c), cyclin A2 (promotes DNA synthesis), caspaserecruiting domain IL 1 activator enzyme (CARDIAK), and MAP kinase (ras) activator (CRAF1). Six apoptotic geneswere expressed at higher levels in apoptotic MDP treated RKcells than in control RKcells. These included TNF receptoractivator of NFß (TRANK), human apoptosis relatedfactor (TFAR15), cyclin dependent kinase (cdc 2), glyceraldehyde 3 phosphatedehydrogenase (GAPDH), protein inhibitor of NOS (PIN), and sentrin(inhibitor of Fas/APO 1 and TNF induced cell death).Constitutive genes were detected in the control and MDP treatedRKcells in human apoptosis genes arrays. Some of the wereidentified as caspase 6, DNA fragmentation factor (DFF40), cyclophilin, cyclooxygenase 1 (COX 1), cytochromeP450 (metabolizes arachidonic acid), poly(ADP ribose)polymerase (PARP), endogenous apoptosis suppressor (DAD 1),redox factor 1 (ref 1), retinoid X receptor (RxR ß)and iNOS. Several apoptotic genes were detectedin MDP induced apoptotic RKcells using human and mouseapoptosis gene arrays. Our results suggest that the apoptoticpathway induced by MDP in RKcells differs from the apoptoticpathway induced by LPS in monocytes. While other apoptotic genesmay have been detected using a rabbit apoptosis gene array (i.e.,casapase 3), the data are compatible with activation ofcaspase 3 and the known effects of COX inhibitors on MDP inducedapoptosis and uveitis.

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