| Popis: |
Our group has shown that the SHR Y chromosome contains a locus that is responsible for increased blood pressure (BP) in SHR males compared to females. We recently identified multiple Sry genes on the Y chromosome of a single male SHR/Akr (Sry1, Sry2, Sry3, Sry3A, Sry3B, Sry3B1, and Sry3C). Strong support for Sry1 as a candidate hypertension locus comes from studies where we delivered Sry1 sequences to male WKY rats and saw a BP increase comparable to the increased BP in the SHR/y rat. Importantly, Sry2 sequences had no effect on BP. This raises the question of what is different between Sry protein isoforms that could account for their differential effects on BP. In the current study, I tested the hypothesis that Sry proteins differentially activate target genes, and localize differently in cells expressing each protein and that these conditions are a reflection of their slightly different amino acid sequences. Specific Aim 1: Determined if Sry proteins are posttranslationally modified by small ubiquitin like modifiers (SUMO)1, 2 and 3, and characterized Sry phosphorylation state using anti-phosphoserine and anti-phosphothreonine antibodies. Specific Aim 2: Tested the effects of modifying/deleting a glutamine-rich potential transcription activator domain in Sry1/3 vs. Sry2 on activation of an Sry inducible luciferase reporter. Specific Aim 3: Determined the effects of amino acid differences between Sry1/3 and Sry 2 at position 21 (arginine -R vs. histidine -H), amino acids in a nuclear localization sequence (NLS), on promoter-regulatory activity of Sry proteins. Specific Aim 4: Determine the effects that making changes in the NLSs and Q-rich domain have on nuclear localization. Results from these studies demonstrate that differences at the N-terminal NLS reduce Sry nuclear translocation and Sry is potentially phosphorylated at serine residues but not a target of sumoylation. Further, these studies show that amino acid variability among Sry proteins result in different biochemical and intracellular activities. This is consistent with the loss of hypertensive potential for Sry2, and helps in understanding the functional differences among the Sry loci. Further, these data predict that the Sry3-like loci should also increase BP, similar to and perhaps even more than, Sry1. |
