Ischemic postconditioning prevents ischemic acute renal failure.

INTRODUCTION: Delayed graft function (DGF), a frequent complication after kidney transplantation, decreases graft survival. Ischemia/reperfusion (I/R) injuries play a major role in DGF pathophysiology. Because ischemic postconditioning (IP) is efficient to prevent myocardial I/R injuries and reduce infarct size, we sought to describe renal effects of IP. MATERIALS AND METHODS: Swiss mice were divided into three groups after left nephrectomy. Thirty minutes of right kidney ischemia followed by three cycles of 30 seconds of ischemia and reperfusion (IP group: n = 12) versus immediate reperfusion (n = 7). Left nephrectomized and right kidney sham operated mice were used as control groups (n = 6). Mice were followed for an 8-day survival analysis. Serum levels of creatinine and protein as well as weights were determined 2 days before and at days 2 and 8 after surgery. RESULTS: IP improved kidney function on day 2; the mean serum creatinine level was 1.25 +/- 0.71 versus 2.9 +/- 1.3 mg/dL in the immediate reperfusion group (P < .02). We also observed a trend toward increased animal survival (25% vs. 0% in the immediate reperfusion group; P = .10). Despite a significant increase in proteinuria among all groups, there was no significant difference. CONCLUSION: In a mouse model, IP seems to prevent postischemic acute renal failure after 30 minutes of kidney ischemia.

Characterization of two Sp1 binding sites of the human sex determining SRY promoter.

To investigate the molecular basis of the human SRY gene regulation, we have examined the significance of two potential binding sites for the transcription factor Sp1 (Sp1A: -124 to -131 and Sp1B: -147 to -154) by DNase I footprinting and gel mobility shift assays. Cotransfection experiments in Drosophila SL2 cells implicated Sp1 protein in the transcriptional activation of the SRY promoter.

Further complexity of the human SOX gene family revealed by the combined use of highly degenerate primers and nested PCR.

SOX proteins contain a conserved HMG-related DNA-binding domain. They fulfill essential functions during the development of animals. Mutations in several SOX genes have been implicated in human diseases. We present here a new set of PCR primers designed to amplify a broad range of SOX HMG-box sequences. These primers facilitated the cloning of several new SOX HMG boxes from human genomic DNA, revealing unexpected complexity of the SOX gene family.

The human testis determining factor SRY: a new member of the HMG box protein family.

The product of the sex-determining gene SRY is a member of the HMG box containing protein superfamily. The HMG box is a DNA-binding domain of about 80 amino acids shared by many proteins with diverse functions. It seems that the functions of the full length protein are restricted to the HMG box but their molecular basis remains to be determined. We have summarized here the properties of this binding domain described so far in the literature and, using a synthetic peptide mimicking the DNA binding domain (SRY80), we have confirmed the existence of DNA minor groove contacts with this domain. Using intrinsic fluorescence of the tryptophane, the interaction between SRY80 and the putative target sequence AACAAAT was also quantified. In conclusion, we also consider the possible putative action of SRY to fulfill its role in sex determination.

Description and functional implications of a novel mutation in the sex-determining gene SRY.

The sex-determining gene SRY was screened for molecular alteration in an XY sex-reversed female by single-strand conformation polymorphism (SSCP) technique. An A-to-G transition was detected which leads to an exchange of a tyrosine by a cysteine in the SRY protein. The affected tyrosine residue located at the C terminus of the DNA binding protein is evolutionarily strongly conserved among the members of the HMG box containing proteins. Using gel shift assay and peptide synthesis such a mutation is shown to abolish the SRY protein DNA binding ability. The involvement of this particular amino acid in the binding specificity is also discussed.

Diversification pattern of the HMG and SOX family members during evolution.

From a database containing the published HMG protein sequences, we constructed an alignment of the HMG box functional domain based on sequence identity. Due to the large number of sequences (more than 250) and the short size of this domain, several data sets were used. This analysis reveals that the HMG box superfamily can be separated into two clearly defined subfamilies: (i) the SOX/MATA/TCF family, which clusters proteins able to bind to specific DNA sequences; and (ii) the HMG/UBF family, which clusters members which bind non specifically to DNA. The appearance and diversification of these subfamilies largely predate the split between the yeast and the metazoan lineages. Particular emphasis was placed on the analysis of the SOX subfamily. For the first time our analysis clearly identified the SOX subfamily as structured in six groups of genes named SOX5/6, SRY, SOX2/3, SOX14, SOX4/22, and SOX9/18. The validity of these gene clusters is confirmed by their functional characteristics and their sequences outside the HMG box. In sharp contrast, there are only a few robust branching patterns inside the UBF/HMG family, probably because of the much more ancient diversification of this family than the diversification of the SOX family. The only consistent groups that can be detected by our analysis are HMG box 1, vertebrate HMG box 2, insect SSRP, and plant HMG. The various UBF boxes cannot be clustered together and their diversification appears to be extremely ancient, probably before the appearance of metazoans.

The human testis determining factor SRY binds a nuclear factor containing PDZ protein interaction domains.

The human Y-linked testis determining gene SRY encodes a protein with a DNA binding domain from the high mobility group box family. To date, no function has been assigned to amino acid sequences located outside this DNA binding motif. Here, we identify in a yeast two-hybrid screen a PDZ protein termed SIP-1, as an interacting protein with human SRY. In vitro, biochemical analysis, immunoprecipitation experiments, as well as expression of SIP-1 in human embryonic testis confirm that the two proteins can interact together. Interacting domains were mapped to the C-terminal seven amino acids of SRY and to the PDZ domains of SIP-1, respectively. We hypothesize that SIP-1 could connect SRY to other transcription factors providing SRY for its missing trans-regulation domain.