Na^+/HCO_3^- cotransporter is expressed on β and α cells during rat pancreatic development

AIM To determine the expression and localization of the electrogenic Na^+/HCO_3^- cotransporter(NBC1) in rat pancreas during development. METHODS The rat pancreas from postnatal and embryos removed from the uterus of pregnant rats that had been sacrificed by CO2 asphyxiation were used. Rat pancreas from embryonic day(E) 15.5 and E18.5 rat embryos was isolated under a stereomicroscope. Rat pancreas from postnatal(P) days 0, 7, 14, 21 and adult was directly isolated by the unaided eye. The RT-PCR analysis of the NBC1 specific region on rat pancreastissues from different developmental stages. The two antibodies which target the NBC1 common COOHterminal region and NH2-terminal region detected a clear band of about 145 k Da in the Western blot analysis. The localization of NBC1 was examined by immuno-fluorescence detection. RESULTS The results revealed the first peak of NBC1 expression at E18.5 and the second peak at P14. Meanwhile, the low NBC1 expression occurred at P7 and adult stages. Our results demonstrated, for the first time, the presence of NBC1 in the plasma membrane of β and α cells, as well as in the basolateral membrane of acinar cells of the rat pancreas at different stages of development. CONCLUSION The data strongly suggests that NBC1 is diversely expressed in the pancreas at different developmental stages, where it may exert its functions in pancreatic development especially islet cell growth through HCO_3^- transport and pH regulation.

Types of voltage-dependent calcium channels involved in high potassium depolarization-induced amylase secretion in the exocrine pancreatic tumour cell line AR4-2J

In the perifused fura-2 loaded exocrine pancreatic acinar cell line AR4-2J pulses of high potassium induced repetitive increases in intracellular calcium. Attached cells when stimulated with high potassium secreted large amount of amylase. High potassium-induced secretion was dependent both on the concentration of potassium and duration of stimulation. High potassium induced increases in intracellular calcium were inhibited by voltage-dependent calcium channel antagonists with an order of potency as follows: nifedipine > ω-agatoxin IVA > ω-conotoxin GVIA. In contrast, the L-type calcium channel antagonist nifedipine almost completely inhibited potassium-induced amylase secretion, whereas the N-type channel antagonist ω-conotoxin GVIA was without effect. The P-type channel antagonist ω-agatoxin IVA had a small inhibitory effect, but this inhibition was not significant at the level of amylase secretion. In conclusion, the AR4-2J cell line possesses different voltage-dependent calcium channels (L, P,N) with the L-type predominantly involved in depolarization induced amylase secretion.

Exosomal miR-485-3p derived from pancreatic ductal epithelial cells inhibits pancreatic cancer metastasis through targeting PAK1

Background:Cell competition is an important feature in pancreatic cancer(PC)progression,but the underlying mechanism remains elusive.This study aims to explore the role of exosomes derived from normal pancreatic ductal epithelial cells involved in PC progression.Methods:PC cells and pancreatic stellate cells(PSCs)were treated with exosomes isolated from pancreatic ductal epithelial cells.Cell proliferation was assessed by CCK8 assays.Cell migration and invasion were assessed by Transwell assays.PC and matched adjacent non-tumor tissue specimens were obtained from 46 patients pathologically diagnosed with PC at Peking University First Hospital from 2013 to 2017.Tissue miR-485-3p and p21-activated kinase-1(PAK1)expression was examined by real-time polymerase chain reaction(RT-PCR),and the relationship of the two was analyzed using Pearman’s product-moment correlation.The clinical significance of miR-485-3p was analyzed using the Chi-square test,Wilcoxon rank-sum test,and Fisher exact probability,respectively.The binding of miR-485-3p to PAK15’-untranslated region(5’-UTR)was examined by luciferase assay.PC cells were xenografted into nude mice as a PC metastasis model.Results:Exosomes from pancreatic ductal epithelial cells suppressed PC cell migration and invasion as well as the secretion and migration of PSCs.MiR-485-3p was enriched in the exosomes of pancreatic ductal epithelial cells but deficient in those of PC cells and PSCs,in accordance with the lower level in PSCs and PC cells than that in pancreatic ductal cells.And the mature miR-485-3p could be delivered into these cells by the exosomes secreted by normal pancreatic duct cells,to inhibit PC cell migration and invasion.Clinical data analysis showed that miR-485-3p was significantly decreased in PC tissues(P<0.05)and was negatively associated with lymphovascular invasion(P=0.044).As a direct target of miR-485-3p,PAK1 was found to exert an inhibitory effect on PC cells,and there was a significantly negative correlation between the expression levels of miR-485-3p and PAK1(r=-0.6525,P<0.0001)in PC tissues.Moreover,miR-485-3p could suppress PC metastasisin vivo by targeting p21-activated kinase-1.Conclusions:Exosomal miR-485-3p delivered by normal pancreatic ductal epithelial cells into PC cells inhibits PC metastasis by directly targeting PAK1.The restoration of miR-485-3p by exosomes or some other vehicle might be a novel approach for PC treatment.

乙醇对胰岛β细胞功能及胰岛素基因表达影响

目的观察乙醇对原代培养的大鼠胰岛细胞及小鼠胰岛瘤细胞(NIT-1细胞)胰岛素分泌功能的影响并探讨其机制。方法体外培养的大鼠胰岛细胞及NIT-1细胞,不同剂量乙醇作用不同时间后,用放免法测定胰岛素分泌情况,RT-PCR方法检测胰岛素mRNA的表达。结果(1)乙醇对NIT-1细胞胰岛素分泌及胰岛素mRNA表达影响:作用6 h,胰岛素分泌增加,各剂量组(除400 mmol/L)胰岛素mRNA表达升高;作用12,24 h,胰岛素分泌降低,胰岛素mRNA表达均降低。(2)乙醇对原代培养的大鼠胰岛细胞的胰岛素分泌及胰岛素mRNA表达影响:作用12 h,低剂量组胰岛素分泌升高,胰岛素mRNA表达升高,高剂量组胰岛素分泌下降;胰岛素mRNA表达下降;随乙醇作用时间延长,胰岛素分泌先升高(6 h),然后下降(24 h),胰岛素mRNA表达短时间(6 h)上升,作用24 h表达下降。结论乙醇对胰岛β细胞胰岛素分泌及胰岛素mRNA表达的影响与作用时间、剂量有关,胰岛素mRNA表达水平的改变可能是乙醇影响胰岛β细胞胰岛素分泌的机制之一。

A non-human primate derived anti-P-selectin glycoprotein ligand-1 antibody curtails acute pancreatitis by alleviating the inflammatory responses

Acute pancreatitis(AP)is a devastating disease characterized by an inflammatory disorder of the pancreas.P-selectin glycoprotein ligand-1(PSGL-1)plays a crucial role in the initial steps of the adhesive at process to inflammatory sites,blockade of PSGL-1 might confer potent anti-inflammatory effects.In this study,we generated two non-human primate derived monoclonal antibodies capable of efficiently targeting human PSGL-1,RH001-6 and RH001-22,which were screened from immunized rhesus macaques.We found that RH001-6,can effectively block the binding of P-selectin to PSGL-1,and abolish the adhesion of leukocytes to endothelial cells in vitro.In vivo,we verified that RH001-6 relieved inflammatory responses and pancreatic injury in both caerulein and L-arginine induced AP models.We also evaluated the safety profile after RH001-6 treatment in mice,and verified that RH001-6 did not cause any significant pathological damages in vivo.Taken together,we developed a novel non-human primate derived PSGL-1 blocking antibody with high-specificity,named RH001-6,which can interrupt the binding of PSGL-1 and P-selectin and attenuate inflammatory responses during AP.Therefore,RH001-6 is highly potential to be further developed into therapeutics against acute inflammatory diseases,such as AP.