新型阿片受体配基特异性结合μ受体并抑制cAMP生成

本文研究新合成阿片受体配基对稳定表达 μ阿片受体的CHO细胞的受体结合特性和对胞内cAMP的抑制作用。采用放射性配基结合的方法研究了阿片受体配基 [3H] diprenorphine(3H dip)在稳定表达 μ阿片受体的CHO细胞模型上 ,对 μ阿片受体的饱和性结合特征及和一系列新合成阿片配基A、B、C、D、E、F、G、及DAMGO([D Ala ,N Me Phe4 ,Gly ol5] enkephalin)和吗啡的竞争性结合特征。利用竞争性结合蛋白法测定阿片受体配基对胞内cAMP的抑制作用。 [3H] diprenorphine结合 μ阿片受体的Kd值为 1 0 6nmol L ;Bmax为 930fmol mg蛋白。结果表明新配基、DAMGO和吗啡竞争性结合 μ受体的IC50 值分别为 13 33± 3 73、14 36± 1 5 8、0 6 2± 0 0 3、5 6 38± 2 33、6 5 72±2 6 4 4、33 10± 11 33、0 5 5± 0 0 6、3 6 9± 1 5 9和 1 83± 0 5 0。其中C和G配基对 μ阿片受体的亲和力高于DAMGO和吗啡。B、D、E和F配基对μ受体的亲和力低于DAMGO和吗啡。新配基、DAMGO和吗啡抑制cAMP生成的IC50 值分别为 6 4 9± 1 5 9、1390± 6 1 10、0 84± 0 11、2 33± 1 2 4、2 5 0 0± 17 2 0、1 4 2± 1 2 1、0 0 1± 0 0 1、0 10± 0 0 5和0 0 4± 0 0 1。其中G配基的抑制胞内cAMP作用最强 ,强于吗啡 ,类     

树鼩血栓性脑缺血时单胺氧化酶活性的变化及银杏内酯B作用机制探讨

目的 :揭示血栓性脑缺血时缺血区和血清单胺氧化酶 (MAO)活性变化及对血小板活化因子 (PAF)受体拮抗剂银杏内酯B(GB)作用机理的探讨。方法 :建立光化学诱导树鼠句血栓性脑缺血模型 ,用酶比色法测量缺血后4、2 4及 72h中心区、半暗区、对侧区及血清的MAO活性 ,并用双缩脲法测定上述各区的蛋白含量。结果 :脑缺血后不同时间缺血中心区MAO活性显著低于假手术组 [(15 4 1± 1 6 3)× 10 3 U/g蛋白 ]或对侧区 [(15 4 7± 1 6 8)× 10 3 U/g蛋白 ],以 72h最为明显 [(2 19± 1 96 )× 10 3 U/g蛋白 ,P <0 0 1];此时缺血半暗区和血清MAO活性 [分别为 (2 5 30± 2 0 1)× 10 3 U/g蛋白和 (2 10 0 4± 2 6 6 7)× 10 3 U/L]明显高于假手术组 (P <0 0 1)。光化学反应后 6h舌下静脉一次注射PAF受体拮抗剂GB(5mg·kg-1)后 2 4h时 ,半暗区MAO活性明显低于缺血组 ,而中心区则高于缺血组 (P <0 0 1)。MAO活性变化与相应区域蛋白含量改变一致 (r=0 81,P <0 0 5 )。结论 :脑缺血后中心区、半暗区MAO活性改变是相应区域单胺类递质消长变化的主要原因 ,MAO活性变化与神经元蛋白质合成能力的改变有关 ;GB的脑保护作用与其拮抗PAF受体和调节MAO活性而促进递质平衡有关。     

骨关节炎与免疫关联性初探

为了探讨免疫因素是否介导骨关节炎的发病 ,应用直接免疫荧光法检测了 6例晚期骨关节炎患者滑膜液中浸润淋巴细胞分化抗原的表达 ,同时用微量酶联免疫技术测定了这些患者滑膜液中IL 10、IL 12和sFasL的含量。结果显示关节滑膜液中的淋巴细胞以CD8+ 细胞为主 (6 7 0 %± 14 6 %) ,远远高于CD4+ 细胞 (15 0 %± 12 8%) ,两者相差显著 (P <0 0 1)。CD4+ /CD8+ 比值 <1。进一步分析表明其T细胞受体主要为αβ型TCR (6 4 0 %± 12 6 %)。滑膜液中IL 12含量 (2 0 3 84±49 2 )pg/ml高于IL 10 (37 8± 14 5 )pg/ml,有明显统计学差异 (P <0 0 1)。外周血中IL 10和IL 12的含量分别为 (4 3 37±14 2 )pg/ml和 (4 5 5 8± 10 6 )pg/ml。血清中sFasL含量较高 (15 3 90± 5 6 )pg/ml,而滑膜液中则很低 (<5pg/ml,P <0 0 1)。提示在骨关节炎的晚期CD8+ 淋巴细胞和IL 12增高可能参与了关节的免疫损伤。     

低氧诱导因子-1α和内皮素-1基因在大鼠低氧性肺动脉高压中的表达

目的　探讨低氧诱导因子 1(HIF 1α)和内皮素 1(ET 1)基因表达在低氧性肺动脉高压发病过程中的变化和作用。方法　复制低氧性肺动脉高压大鼠模型 ,测定平均肺动脉压 ,弹力纤维染色显示腺泡内肺动脉 ,用放射免疫法测ET含量 ,原位杂交方法进行检测HIF 1αmRNA。结果　HIF 1αmRNA在低氧各组腺泡内肺动脉有表达 ,低氧 14d组 (0 2 5 6 9± 0 0 46 8)和低氧 2 8d组 (0 2 2 5 8±0 0 45 3)染色强于低氧 5d组 (0 145 5± 0 0 2 72 )和正常组 (0 110 9± 0 0 2 2 4) ;ET 1mRNA在低氧各组腺泡内肺动脉有表达 ,低氧 14d组 (0 412 2± 0 0 783)和低氧 2 8d组 (0 36 84± 0 0 72 9)染色强于低氧5d组 (0 2 0 17± 0 0 34 9)和正常组 (0 185 5± 0 0 36 1) ,HIF 1α和ET 1基因表达在H14d组和H2 8d组明显增加 (P <0 0 5 )。肺动脉血中ET 1含量在H14d组 [(15 8 78± 2 5 14)pg/ml]和H2 8d组 [(142 93± 2 3 38)pg/ml]明显高于H5d组 [(79 6 8± 12 5 4)pg/ml]和正常组 [(6 5 37± 10 82 )pg/ml](P <0 0 5 ) ;H14d组 [(34 0± 5 8)mmHg]和H2 8d组 [(2 9 0± 4 7)mmHg]的mPAP也明显高于H5d组[(19 0± 3 5 )mmHg]和正常组 [(17 0± 2 8)mmHg](P <0 .0 5 ) ,并且与肺动脉血中ET 1含量呈正比(rs=0     

Aβ_((31-35))和ApoE_4对培养大鼠海马神经元的存活和生长的影响

为探讨β-淀粉样蛋白 ( Aβ)和载脂蛋白 E4( Apo E4)对培养大鼠海马神经元的作用 ,本文采用了神经细胞培养、MTT比色法、免疫组化及图象分析等技术进行了研究。结果显示 :( 1) MTT法测得 Aβ( 3 1 - 3 5) ( 10 μmol/ L) +Apo E4( 10 μg/ ml)和 Aβ( 3 1 - 3 5)( 2 0μmol/ L ) +Apo E4( 10μg/ ml)的 OD值 ,分别为 0 .197± 0 .0 2 1和 0 .191± 0 .0 2 4,明显低于对照组 ( 0 .2 2 9± 0 .0 3,P<0 .0 5 )。( 2 )这两组神经元胞体的最长径分别为 ( 10 .0 7± 1.98)μm和 ( 10 .0 1± 1.6 8)μm;最短径分别为 ( 6 .40± 0 .77)μm和 ( 6 .2 8± 0 .89) μm,明显低于对照组、Apo E4组、Aβ( 3 1 - 3 5) 组的最长径和最短径 ( P<0 .0 5 ) ;其突起平均长度分别为 ( 2 6 .36± 7.73) μm和 ( 2 3.86± 7.2 9)μm,明显低于对照组 ( 30 .88± 9.79)μm、Apo E4组 ( 30 .6 0± 7.30 )μm以及 Aβ( 3 1 - 3 5) ( 10μmol/ L )组 ( 2 8.34± 4.40 )μm( P<0 .0 5 )。 ( 3) Aβ( 3 1 - 3 5) ( 2 0 μmol/ L)组的突起平均长度为 ( 2 6 .81± 5 .42 ) μm,也明显低于对照组 ( 30 .88± 9.79) μm和Apo E4组 ( 30 .6 0± 7.30 )μm ( P<0 .0 5 )。本研究结果提示 ,Aβ( 3 1 - 3 5) +Apo E4对神经元的抑制作用较 Aβ(     

N-甲基-D-门冬氨酸受体与使君子酸受体在培养海马神经元树突上的膜表面表达与共定位

目的　研究含NR2B亚单位的N 甲基 D 门冬氨酸 (NMDA)受体 (NR2B NMDAR)与含GluR1亚单位的使君子酸 (AMPA)受体 (GluR1 AMPAR)在发育不同阶段的培养海马神经元树突上的膜表面表达与共定位。　方法　以FLAG NR2B和GFP GluR1表达载体共转染原代培养第 5d(DIV5 )的大鼠海马神经元 ,分别用相应特异性抗体和荧光标记二抗作活细胞染色 ,显示膜表面表达的受体簇。　结果　对DIV7和DIV14的培养海马神经元树突表面受体簇计数 (个数 10 0 μm) ,GluR1 AMPAR受体簇分别为 5 9 2± 5 6和 74 8± 3 1(P <0 0 5 ) ;NR2B NMDAR为 38 7±3 5和 80 8± 4 9(P <0 0 1) ;两者共定位为 16 3± 5 2和 4 0 1± 6 0 (P <0 0 1)。DIV14海马神经元 4 0 %的共定位受体簇分布在树突棘上。　结论　随着海马神经元的发育 ,树突膜表面NR2B NMDAR、GluR1 AMPAR及两者共定位受体簇密度均增加 ,提示 ,形成更多具有活性的兴奋性突触 ,且主要位于树突棘上。     

新合成阿片受体配基对δ受体的激动作用

研究新合成的阿片受体配基对δ阿片受体的激动作用。采用生物鉴定的方法 ,检测新型阿片受体配基、DP DPE和吗啡对小白鼠输精管 (MVD)收缩的抑制作用和检测所激动的阿片受体亚型 ,以达到最大抑制作用的 5 0 %的药物浓度 (IC50 值 )评价效价强度。结果表明新型阿片受体配基、DPDPE和吗啡 (Mor)都可抑制MVD的电刺激收缩 ,显示纯激动剂作用。认为新型阿片受体配基与阿片受体的结合为可逆性结合。新型阿片受体配基A、C、D、E、F和G以及典型的阿片受体激动剂DPDPE和吗啡的IC50 值分别为 31 73± 3 5 4、15 92± 9 19、88 70± 16 2 6、10 74 0 0± 2 6 3 0 0、74 88± 5 8 6 9和 6 7 16± 8 4 9、3 2 0± 0 0 5、6 9 84± 2 7 5 8nmol L。竞争性拮抗剂纳洛酮 (Nal)可拮抗配基的激动作用 ,使新型阿片受体配基 ,DPDPE和吗啡的量效曲线平行右移。新型阿片受体配基可激动δ阿片受体 ,是典型的δ受体激动剂     

慢性肾衰大鼠继发甲状旁腺功能亢进时腺体钙敏感受体的观察

研究慢性肾衰 (CRF)继发性甲旁亢 (2°HPT)大鼠发病时及 1,2 5 (OH) 2 D3 治疗时甲状旁腺钙敏感受体 (PCaR)mRNA含量变化。采用肾大部分切除大鼠 2°HPT模型 ,动物分为CRF组 ,治疗组 ,假手术组。治疗组予以 1,2 5(OH) 2 D3(2 5pmol d× 10腹腔注射 ) ,31d后测定生化指标及PCaRmRNA含量 ,后者采用逆转录聚合酶链反应 (RT PCR)半定量法。(1)CRF组大鼠较假手术组血肌酐 (SCr) (6 9 30± 11 2 0vs 2 1 15± 8 2 0 μmol L ,P <0 0 5 )及甲状旁腺素 (PTH) (2 5 6± 72vs 41± 7pg mL ,P <0 0 5 )明显上升 ,治疗组PTH较CRF组明显下降 (112± 47vs 2 5 6± 72pg mL ,P <0 0 5 )。(2 )CRF组大鼠PCaRmRNA与假手术组含量无明显差异 (1 10 0± 0 15 3vs 1 0 74± 0 119) ,治疗组PCaRmRNA与CRF组含量无明显差异 (1 131± 0 10 8vs1 0 74± 0 119)。本实验 2°HPT模型PCaRmRNA表达无明显变化 ,1,2 5 (OH) 2 D3治疗肾大部切除 2°HPT大鼠对PCaRmRNA水平无显著影响     

过氧化氢对大鼠海马CA1区神经元钠电流的影响

目的与方法 :采用全细胞膜片钳技术研究过氧化氢 (H2 O2 )对急性分离的大鼠海马CA1区神经元钠电流的影响。结果 :①过氧化氢可剂量依赖地增大钠电流 ,剂量为 10 μmol/L和 10 0 μmol/L时 ,钠电流分别增大 4 8 0 %± 4 2 %和 88 2 %± 5 1% (n =10 )。② 10 μmol/L的H2 O2 不影响钠电流的激活过程 ,却非常显著地影响其失活过程 ,作用前后的半数失活电压分别为(- 6 4 5 8± 1 2 2 )mV和 (- 5 3 5 5± 0 94 )mV(n =10 ,P <0 0 1) ,但不改变失活曲线的斜率因子。结论 :H2 O2 作为体内氧化代谢产物可能与一些神经系统疾病的发生有关…     

类风关滑膜浸润T细胞特性与致病机制研究

为研究类风湿关节炎时关节滑膜浸润性T细胞生物学特性与致病机制 ,对 10例RA患者滑膜液中淋巴细胞的免疫表型、细胞因子分泌格局与趋化因子受体表达进行了分析。用双色荧光标记法分别测定滑膜液中和外周血淋巴细胞表型与趋化因子受体表达。用ELISA方法检测滑膜液与外周血中IFN γ、IL 10、IL 4与IL 12的含量。结果是滑膜液中的CD4 + T淋巴细胞为 4 0 0 %± 11% ,CD8+ T细胞为 34 0 %± 6 % ,CD4 + 与CD8+ T细胞的比值为 1 2 ,显著低于外周血中CD4 /CD8的比值。滑膜液中CD3和CD2 5双阳性的活化T细胞占 16 %± 6 0 %。趋化因子受体CCR5表达较低 ,与外周血无明显差异。但CX CR3表达水平较高 ,为 16 %± 4 0 % ,远远高于外周血 (仅为 0 5 %± 0 3% )。IFN γ在滑膜液中含量很高 ,达 (36 6 7± 4 3 2 )pg/ml,而外周血中含量仅为 (2 0 1± 3 2 )pg/ml。IL 4含量未能测得 (<15pg/ml ) ,与外周血相似。IL 12含量为 (4 19 9±89 2 )pg/ml,远高于外周血中的含量 (6 5 32± 34 2 )pg/ml。IL 10含量为 (187 7± 34 5 )pg/ml,高于外周血中的含量 (85±12 7)pg/ml。在所测细胞因子中 ,关节滑膜液中IFN γ和IL 12的含量与外周血相比具有显著的统计学差异。表明RA关节滑膜液中有相当数量的T细胞浸润。这些T细胞     

氧化低密度脂蛋白内皮受体在氧化低密度脂蛋白致内皮细胞损伤中的作用

目的:探讨血凝素样氧化低密度脂蛋白受体(LOX1)在氧化低密度脂蛋白(ox-LDL)致内皮细胞损伤中的作用。方法:采用倒置相差显微镜观察细胞形态的改变;发色底物法检测内皮细胞培养液中的组织纤溶酶原激活物(t-PA)和纤溶酶原激活物抑制剂(PAI-1)的活性;反转录聚合酶链反应(RT-PCR)检测LOX1mRNA表达水平。结果:单纯加入ox-LDL,内皮细胞出现胞体收缩,细胞膜破坏等明显的损伤性改变,培养液中PAI-1活性较对照组高3倍(P<0.05),LOX1mRNA水平表达增高;而当培养液中同时加有LOX1抑制剂polyinosinicacid时,内皮细胞形态损伤不明显,培养液中PAI-1活性低约2.6倍(P<0.05),同时LOX1mRNA水平降低。结论:LOX1介导了ox-LDL对内皮细胞的损伤,可能在血管损伤性疾病的发生中起重要作用。     

Transforming growth factor-β1 mediated up-regulation of lysyl oxidase in the kidneys of hereditary nephrotic mouse with chronic renal fibrosis

Lysyl oxidase (LOX), an extracellular emzyme, plays a key role in the post-translational modification of collagens and elastin, catalyzing inter- and intra-crosslinking reactions. Because the crosslinked extracellular matrices (ECMs) are highly resistant to degradative enzymes, it is considered that the over-expression of LOX may cause severe fibrotic degeneration. In the present study, we addressed the role of LOX-mediated crosslinking in chronic renal tubulointerstitial fibrosis using an animal model of hereditary nephrotic syndrome, the Institute of Cancer Research (ICR)-derived glomerulonephritis (ICGN) mouse. Ribonuclease protection assay (RPA) revealed that LOX mRNA expression was up-regulated in the kidneys of ICGN mice as compared with control ICR mice. High-level expression of LOX and transforming growth factor (TGF)-β1 (an up-regulator of LOX) mRNA was detected in tubular epithelial cells of ICGN mouse kidneys by in situ hybridization. Type-I and -III collagens, major substrates for LOX, were accumulated in tubulointerstitium of ICGN mouse kidneys. The present findings imply that TGF-β1 up-regulates the production of LOX in tubular epithelial cells of ICGN mouse kidneys, and the excessive LOX acts on interstitial collagens and catalyzes crosslinking reactions. As a result, the highly crosslinked collagens induce an irreversible progression of chronic renal tubulointerstitial fibrosis in the kidneys of ICGN mice.     

碱性成纤维细胞生长因子和骨髓间充质干细胞构建的组织工程心脏瓣膜赖氨酰氧化酶的表达

目的 探讨碱性成纤维细胞生长因子(bFGF)和骨髓间充质干细胞(MSC)构建组织工程心脏瓣膜(TEHV)及其赖氨酰氧化酶(LOX)的表达.方法 贴壁培养法分离、培养和纯化大鼠MSC,取第3代种植于去细胞瓣叶支架上.分别将瓣叶置于含10 μg/L bFGF的培养液(A组)、普通培养液(B组)中构建TEHV,大鼠肌成纤维细胞构建的TEHV为C组,培养14 d后,采用Amplex red荧光法检测各组中的LOX蛋白含量,RT-PCR检测LOX mRNA表达.结果 B组的LOX蛋白含量和mRNA表达[(0.137±0.003)mg/L,2.08±0.03]高于A组[(0.124±0.002)mg/L,0.87±0.01]和C组[(0.127±0.002)mg/L,0.90±0.01](P<0.05),A、C两组差异无统计学意义(P>0.05).结论 bFGF可能通过降低MSC的LOX表达,使MSC构建的TEHV达到与肌成纤维细胞构建的类似.     

高碳酸血症通过赖氨酰氧化酶依赖的胶原蛋白交联影响大鼠缺氧性肺动脉高压

目的:通过研究缺氧和/或高碳酸血症时赖氨酰氧化酶(LOX)以及细胞外基质胶原蛋白的交联变化,探讨高碳酸血症对缺氧性肺动脉高压的影响机制。方法:SD大鼠随机均分为4组,分别为常氧对照组、缺氧组、高碳酸血症组以及缺氧+高碳酸血症组。比色法测定胶原蛋白含量,荧光光谱法分析LOX酶活性,免疫组织化学和Western blot法检测肺动脉LOX蛋白含量,实时荧光定量PCR检测肺动脉LOX的mRNA水平。结果:缺氧组大鼠平均肺动脉压(m PAP)、右心室/(左心室+室间隔)重量比值[RV/(LV+S)]及血管壁面积(WA)/血管总面积(TA)均明显高于常氧对照组;高碳酸血症组与常氧对照组的m PAP、RV/(LV+S)差异无统计学显著性;缺氧+高碳酸血症组大鼠的m PAP及RV/(LV+S)显著低于单纯缺氧组。缺氧组大鼠肺组织的胶原交联程度则明显高于常氧组及高碳酸血症组;高碳酸血症组大鼠肺组织的胶原交联程度与常氧组比较无显著差异;缺氧+高碳酸血症组大鼠肺组织的胶原交联程度显著低于缺氧组。缺氧组大鼠肺动脉LOX的mRNA、蛋白表达量及其酶活性均高于常氧组(P0.01);缺氧+高碳酸血症组大鼠肺动脉LOX mRNA、蛋白表达以及酶活性均明显低于缺氧组(P0.01)。结论:缺氧能诱导肺动脉LOX高表达,通过促进胶原合成及交联,参与肺动脉高压的形成。高碳酸血症通过抑制缺氧诱导的LOX表达和胶原交联,延缓缺氧性肺动脉高压的进展。     

Endoplasmic reticulum stress induced LOX‐1+ CD15+ polymorphonuclear myeloid‐derived suppressor cells in hepatocellular carcinoma

A recent study indicated that Lectin‐type oxidized LDL receptor‐1 (LOX‐1) was a distinct surface marker for human polymorphisms myeloid‐derived suppressor cells (PMN‐MDSC). The present study was aimed to investigate the existence LOX‐1 PMN‐MDSC in hepatocellular carcinoma (HCC) patients. One hundred and twenty‐seven HCC patients, 10 patients with mild active chronic hepatitis B, 10 liver cirrhosis due to hepatitis B, 10 liver dysplastic node with hepatitis B and 50 health control were included. LOX‐1⁺ CD15⁺ PMN‐MDSC were significantly elevated in HCC patients compared with healthy control and patients with benign diseases. LOX‐1⁺ CD15⁺ PMN‐MDSC in circulation were positively associated with those in HCC tissues. LOX‐1⁺ CD15⁺ PMN‐MDSCs significantly reduced proliferation and IFN‐γ production of T cells with a dosage dependent manner with LOX‐1^? CD15⁺ PMNs reached negative results. The suppression on T cell proliferation and IFN‐γ production was reversed by ROS inhibitor and Arginase inhibitor. ROS level and activity of arginase of LOX‐1 ⁺CD15⁺ PMN were higher in LOX‐1⁺ CD15⁺ PMN‐MDSCs than LOX‐1^? CD15⁺ PMNs, as well as the expression of the NADPH oxidase NOX2 and arginase I. RNA sequence revealed that LOX‐1⁺ CD15⁺ PMN‐MDSCs displayed significantly higher expression of spliced X‐box ‐binding protein 1 (sXBP1), an endoplasmic reticulum (ER) stress marker. ER stress inducer induced LOX‐1 expression and suppressive function for CD15⁺ PMN from health donor. For HCC patients, LOX‐1⁺ CD15⁺ PMN‐MDSCs were positively related to overall survival. Above all, LOX‐1⁺ CD15⁺ PMN‐MDSC were elevated in HCC patients and suppressed T cell proliferation through ROS/Arg I pathway induced by ER stress. They presented positive association with the prognosis of HCC patients.     

A novel proteolytic processing of prolysyl oxidase

Lysyl oxidase (LOX) is an amine oxidase that is critical for the stability of connective tissues. The secreted proLOX is enzymatically quiescent and is activated through proteolytic cleavage between residues Gly(162) and Asp(163) (residue numbers according to the mouse LOX) by bone morphogenetic protein (BMP)-1 gene products. Here we report a novel processing of proLOX identified in vitro and in vivo. Two forms of mature LOX were identified and characterized by their immunoreactivity to specific antibodies, amine oxidase activity, and mass spectrometry. One form was identified as a well-characterized BMP-1 processed LOX protein. Another was found to be a truncated form of LOX resulting from the cleavage at the carboxy terminus of Arg(192). The truncated form of LOX still appeared to retain amine oxidase activity. The results from the proLOX gene deletion and mutation experiments indicated that the processing occurs independent of the cleavage of proLOX by BMP-1 gene products and likely requires the presence of LOX propeptide. These results indicate that proLOX could be processed by two different mechanisms producing two forms of active LOX.     

A Novel Proteolytic Processing of Prolysyl Oxidase

Lysyl oxidase (LOX) is an amine oxidase that is critical for the stability of connective tissues. The secreted proLOX is enzymatically quiescent and is activated through proteolytic cleavage between residues Gly₁₆₂ and Asp₁₆₃ (residue numbers according to the mouse LOX) by bone morphogenetic protein (BMP)-1 gene products. Here we report a novel processing of proLOX identified in vitro and in vivo. Two forms of mature LOX were identified and characterized by their immunoreactivity to specific antibodies, amine oxidase activity, and mass spectrometry. One form was identified as a well-characterized BMP-1 processed LOX protein. Another was found to be a truncated form of LOX resulting from the cleavage at the carboxy terminus of Arg₁₉₂. The truncated form of LOX still appeared to retain amine oxidase activity. The results from the proLOX gene deletion and mutation experiments indicated that the processing occurs independent of the cleavage of proLOX by BMP-1 gene products and likely requires the presence of LOX propeptide. These results indicate that proLOX could be processed by two different mechanisms producing two forms of active LOX.