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O -Linked N -acetylglucosamine transferase (OGT) was identified as an Nrf1-interacting protein. Herein, we show that Nrf1 enables interaction with OGT and their co-immunoprecipitates are O -GlcNAcylated by the enzyme. The putative O -GlcNAcylation negatively regulates Nrf1/TCF11 to reduce both its protein stability and transactivation activity of target gene expression. The turnover of Nrf1 is enhanced upon overexpression of OGT, which promotes ubiquitination of the CNC-bZIP protein. Furthermore, the serine/theorine-rich sequence of PEST2 degron within Nrf1 is identified to be involved in the protein O -GlcNAcylation by OGT. Overall, Nrf1 is negatively regulated by its O -GlcNAcylation status that depends on the glucose concentrations. [ABSTRACT FROM AUTHOR]

Abstract: Our previous study documented the expression of Mta1 during spermatogenesis. Here, we present evidence for a possible involvement of Mta1 in the regulation of testicular function, possibly by interacting with p53. A notable decrease of Mta1 expression was revealed at postsurgical day 6, consistent with the previously reported upregualtion of p53 in mouse cryptorchidism. Furthermore, in vitro over-expression of Mta1 could remarkably elevate the resistance capability of spermatogenic tumor cells against heat-induced apoptosis with a marked impairment of p53 expression. These findings indicate that Mta1 may operate as a negative modifier of apoptosis by interacting with p53 during gametogenesis. [Copyright &y& Elsevier]