2C). vivo. These data demonstrate that a Risperidone hydrochloride finely-tuned balance of Ran GTPase signaling is essential for postnatal pancreatic islet development and glucose homeostasis,in vivo. == Introduction == As a member of the Ras family of small GTPases[1], the Ran protein orchestrates a multitude of cellular responses, including nucleo-cytoplasmic shuttling[2], various aspects of mitosis[3], and other cytoplasmic transport SHCB mechanisms in specialized cell types[4]. These functions require regulated subcellular compartmentalization of Ran[3], spatial control of its guanine nucleotide cycling[5], and a finely-tuned balance involving plethora of Ran regulatory molecules that monitor the guanine-nucleotide state[6]. Ran signaling is highly Risperidone hydrochloride evolutionary conserved, and is thought to be essential for cellular homeostasis[6]. However, except for transformed cells, where Ran is frequently over-expressed[7], controls the distribution[8], and/or stability[9],[10]of variouscancergenes, and correlates with unfavorable outcome[11],[12], a mechanistic link between deregulated Ran signaling and disease pathogenesis has not been determined. In this study, we generated transgenic mice that express wild type (WT) Ran, the Ran loss-of-function mutant T24N, or the Ran gain-of-function mutant G19V[6]in insulin-producing pancreatic islet cells. Unexpectedly, we found that deregulated Ran signaling under these conditions dramatically impairs postnatal, but not embryonic islet development, triggering hypoinsulinemia, reduced cell proliferation and overt diabetes,in vivo. == Materials and Methods == == Plasmid construction and generation of transgenic mice == All experiments involving animals were approved by an Institutional Animal Care and Use Committee. A full-length human Ran WT cDNA or cDNA encoding the Ran mutant T24N or G19V was fused to an HA tag at the 5 end, and cloned intoBamHIandSpeIsites downstream of the Rat Insulin Promoter (RIP)[13]in pBluescript II KS, containing SV40 polyadenylation sequences at the 3 end. Each RIP-HA-Ran construct (WT, T24N or G19V) was confirmed by DNA sequencing, purified by ion exchange chromatography (Qiagen, Valencia, CA), and microinjected (5 ng/ml) into C57Bl/6 embryos that were implanted into syngeneic recipient pseudopregnant females, as described[14]. Littermates were screened by PCR of tail genomic DNA using primers (10 pmol) corresponding to RIP-HA (forward,5-CTCGAGGGCTGCAGGAATTCGATA-3; reverse5-GCCTTCACTTTCCTGTCCTTAATA-3) or RIP-Ran (forward5-TGGACTA TAAAGCTAGTGGGGATT-3; reverse, (5-GCTGTGTCCCATACATTGAACTTA-3) sequences. PCR reactions (35 cycles) were carried out at 95C for 1 min, 56C for 1 min and 72C for 1 min plus a 10 min extension at 72C. Colonies from independent transgene-positive founder mice or control littermates were established, and bred with C57Bl/6 mice. Two independent colonies per each condition were analyzed for blood glucose levels with comparable results. Plasmid adenoviral (pAd) constructs encoding GFP-Ran-WT, GFP-Ran-T24N or GFP-Ran-G19V were generated using the pAdEasy system, as described previously[14]. == Cell culture, antibodies, and Western blotting == The rat insulinoma cell line INS-1 was the kind gift of R.S. Sherwin (Yale University School of Medicine, New Haven, CT), and was maintained in culture as described[15]. The following antibodies to Ran (Novus Biologicals, Cell Signaling, Santa Cruz), HA (Santa Cruz, Roche Applied Science), insulin (Invitrogen), glucagon (Dako), somatostatin (Dako), Ki-67 (Dako), PDX-1 Risperidone hydrochloride (Upstate Biotechnology), or -actin (Sigma-Aldrich), were used. Restriction enzymes were purchased from New England BioLabs. Pancreas or liver tissues isolated from non-transgenic (non-TG) or Ran transgenic mice were washed in PBS (pH 7.2), suspended in 4 to 5 volumes of cold lysis buffer containing 50 mM Tris-HCl (pH 7.5), 150 mM NaCl, 5 mM EDTA, 50 mM NaF, 0.5% Nonidet P-40, plus protease inhibitors (Roche Applied Science). After 30-min incubation at 4C, tissue extracts were cleared by centrifugation at 14,000 rpm for 20 min at 4C, and analyzed by Western blotting. Alternatively, INS-1 cells were transduced with a lentivirus expressing control pLKO or Ran-directed short hairpin RNA (shRNA) (Open Biosystems), selected with 1 g/ml puromycin, and analyzed by Western blotting. Protein content was determined using a BCA-200 protein assay kit (Pierce). == Pancreatic islet isolation == Pancreatic islets were harvested from control Risperidone hydrochloride or Ran transgenic mice by collagenase P (1 mg/ml) (Sigma-Aldrich).