Abstract


It is well established that small molecular mass GTP-binding proteins [G-proteins] play pivotal roles in the stimulus secretion coupling of glucose-stimulated insulin secretion [GSIS] from the pancreatic beta-cell. Extant studies have also identified regulatory roles for GDP-dissociation inhibitor [GDI] in these signaling events. More recent evidence from our laboratory in INS-1 832/13 cells, rodent and human islets has demonstrated sustained activation of Rac1 [GTP-bound conformation] following exposure to hyperglycemic [20 mM; 24 hrs; HG] conditions. view more

It is well established that small molecular mass GTP-binding proteins [G-proteins] play pivotal roles in the stimulus secretion coupling of glucose-stimulated insulin secretion [GSIS] from the pancreatic beta-cell. Extant studies have also identified regulatory roles for GDP-dissociation inhibitor [GDI] in these signaling events. More recent evidence from our laboratory in INS-1 832/13 cells, rodent and human islets has demonstrated sustained activation of Rac1 [GTP-bound conformation] following exposure to hyperglycemic [20 mM; 24 hrs; HG] conditions. Herein, we investigated alterations, if any, in the subcellular distribution [mislocalization] of Rac1 in INS-1 832/13 cells and normal rat islets exposed to HG conditions. Triton X-114 phase partition assays indicated significant enrichment of Rac1 in the hydrophobic compartment in INS-1 832/13 cells exposed to HG conditions. In addition, Western blot analysis suggested a significant increase in the association of Rac1 [2.77±0.51 fold; n=3; p<0.05] and GDI [1.47±0.12 fold; n=3; p<0.05] with the nuclear fraction isolated [using a commercially available kit] from beta cells exposed to HG conditions. We also observed a marked inhibition in the nuclear translocation of Rac1 in INS-1 832/13 cells expressing a dominant negative mutant of Rac1 [N17Rac1]. In addition, our findings also suggested that pharmacological inactivation of Rac1 using EHT 1864, a known inhibitor of Rac1, prevented HG-induced nuclear translocation of Rac1 in these cells [44±5.46 percent inhibition; n=4; p<0.005]. These findings suggest that active, GTP-bound Rac1 is preferentially translocated to the nuclear compartment in pancreatic beta cells under glucotoxic conditions. In conclusion, we propose that HG conditions promote sustained activation and alterations in the subcellular distribution [nuclear translocation] of Rac1, culminating in the activation of nuclear events, which could contribute to cellular dysfunction of the beta cell.

show less

Share this PosterTalk

About PosterTalks

PosterTalks allows meeting attendees the ability to view these presentations, download or bookmark their favorite presentations, download PDF versions of the posters, ask questions, leave comments, and share presentations with their colleagues – all from the convenience of a smart phone.

Contact Us

Have a question? Click here to contact us. Need technical support? Click here to email support.

© 2018 PosterTalks and Connect BioMed. All other content and data, including data entered into this website are copyrighted by their respective owners.