Western blotting revealed immunoreactive species at 25 kDa (the predicted rab17 molecular weight) and 40 kDa. Mass spectrometry confirmed that both bands are rab17. When we expressed
a prenylation deficient rab17 isoform, the 40 kDa band was lost suggesting the shift in molecular weight is due, in part, to acylation. Because many rabs participate in vesicle docking with members of the SNARE machinery, and because rab17 has been shown to bind syntaxin 3 in kidney, we used GST pulldown assays with WIF-B cell lysates to analyze rab17-syntaxin interactions. We limited our studies to syntaxins 2 and 3 (the apical isoforms) and for our negative control, syntaxin 4 (the basolateral isoform). As predicted, syn-taxin 4 did not bind wild type MEK inhibitor or the mutant rab17s. However, unlike in
kidney, wild type and GTP bound rab17 bound syn-taxin 2, not syntaxin 3. Interestingly, in both cases, only the 40 kDa rab17 species bound syntaxin 2 suggesting acylation is required for syntaxin binding indicating that the two forms have distinct binding properties. Blotting of total membrane fractions from WIF-B cells revealed that the 25kDa species is present in both the soluble and membrane fraction; however, the 40kDa species was detected only in the membrane fraction. Sequence analysis and these preliminary results suggest rab17 may be further post-translationally modified after prenylation to aid rab17-syntaxin 2 interactions. Because rab17 encodes a near perfect sumoylation modification 上海皓元医药股份有限公司 site (LKLE vs. VKXE where *P=L/I/V),
we are currently examining whether the 40kDa species is sumoylated CP-690550 in vivo and whether the modification is required for interaction with members of the SNARE machinery. Disclosures: The following people have nothing to disclose: Anneliese C. Striz, Pamela L. Tuma Background: Natural Killer (NK) cells are mediating killing of activated hepatic stellate cells (HSCs) in liver injury. NK cell impairment leads to fibrosis progression; accompanied with insulin resistance in human Nonalcoholic-Fatty-Liver-Disease (NAFLD). The cytolytic CD56+CD16+ NK cells (CD56dim) compose ∼90% of circulating NK cells; the rest are CD56+CD16-NK cells (CD56bright). Aims: to asses insulin receptor (IR) expressions of receptors over NK cells, and to investigate its potential role to modulate NK cell responses in NAFLD progressions. Patients and Methods: Flow cytometry analysis of peripheral-blood-lymphocytes from 10 healthy volunteers and 72 histology documented NAFLD cases without metabolic syndrome. NAFLD patients with low (F0, F1-2) and advanced fibrosis (F3-4) scoring were included (F scoring correlates with HOMA score). Results: The compositions of CD56dim and CD56bright were similar in all subgroups, with CD56dim predominance (∼60-80%). CD56dim CD107a (NK-granzymes-activation marker) increase from 21.8±3.1% in healthy donors to 40.5±4.1 (Within F0 NAFLD patients, p=0.07), 39.2±3.6 (F1, p=0.06), 31.