Caspase 3 involves in neuroplasticity,microglial activation and neurogenesis in the mice hippocampus after intracerebral injection of kainic acid

Background

The roles of caspase 3 on the kainic acid-mediated neurodegeneration, dendritic plasticity alteration, neurogenesis, microglial activation and gliosis are not fully understood. Here, we investigate hippocampal changes using a mouse model that receive a single kainic acid-intracerebral ventricle injection. The effects of caspase 3 inhibition on these changes were detected during a period of 1 to 7 days post kainic acid injection.

Result

Neurodegeneration was assessed by Fluoro-Jade B staining and neuronal nuclei protein (NeuN) immunostaining. Neurogenesis, gliosis, neuritic plasticity alteration and caspase 3 activation were examined using immunohistochemistry. Dendritic plasticity, cleavvage-dependent activation of calcineurin A and glial fibrillary acidic protein cleavage were analyzed by immunoblotting. We found that kainic acid not only induced neurodegeneration but also arouse several caspase 3-mediated molecular and cellular changes including dendritic plasticity, neurogenesis, and gliosis. The acute caspase 3 activation occurred in pyramidal neurons as well as in hilar interneurons. The delayed caspase 3 activation occurred in astrocytes. The co-injection of caspase 3 inhibitor did not rescue kainic acid-mediated neurodegeneration but seriously and reversibly disturb the structural integrity of axon and dendrite. The kainic acid-induced events include microglia activation, the proliferation of radial glial cells, neurogenesis, and calcineurin A cleavage were significantly inhibited by the co-injection of caspase 3 inhibitor, suggesting the direct involvement of caspase 3 in these events. Alternatively, the kainic acid-mediated astrogliosis is not caspase 3-dependent, although caspase 3 cleavage of glial fibrillary acidic protein occurred.

Conclusions

Our results provide the first direct evidence of a causal role of caspase 3 activation in the cellular changes during kainic acid-mediated excitotoxicity. These findings may highlight novel pharmacological strategies to arrest disease progression and control seizures that are refractory to classical anticonvulsant treatment.     

骨髓间充质干细胞抑制小胶质细胞介导的炎症反应

目的研究骨髓间充质干细胞(Bone Marrow Mesenchymal Stem Cells,BMMSCs)对小胶质细胞介导的炎症反应的抑制作用。方法实验分为四组:组一:小胶质细胞(BV2)生长于DMEM(High Glucose)培养液中;组二:BV2细胞生长于加入脂多糖(LPS)的上述培养液中;组三:BV2细胞、BMMSCs共培养于加入LPS的上述培养液中;组四:骨髓间充质干细胞(BMMSCs)生长于加入LPS的上述培养液中。观察BV2细胞的生长状态、电镜超微结构变化及其分泌的炎症因子TNF-α表达量的变化。结果光镜下BV2细胞密度依次为:组一组三组二,组四中BMMSCs生长状态良好;电镜下可见组二BV2细胞内出现大量肿胀及空泡化的线粒体、内质网等细胞器,少见生长活跃多核仁细胞,同时可见大量崩解细胞,组三细胞状态明显好于组二;BV2细胞分泌的炎症因子TNF-α表达量依次为组二组三组一组四。结论 BM-MSCs抑制小胶质细胞介导的炎症反应,进而发挥神经保护作用。     

大鼠肝脏半乳糖凝聚素-3 cDNA分子多样性分析

半乳糖凝聚素-3(Galectin-3,Gal-3)是一种多功能蛋白,参与机体内的多种生命活动过程。为分析大鼠Rattus norvegicus gal-3 c DNA分子多样性,在分析Gen Bank注册的大鼠gal-3 c DNA序列的同时,从三只不同大鼠个体的肝脏第一链c DNA,共计9个独立实验中克隆gal-3开放阅读框OFR(Open reading frame)。分析结果表明,在已注册的序列中存在1个单核苷酸多态性(Single nucleotide polymorphism,SNP)。本实验从1-3号大鼠肝脏分别获得118、95和120个克隆,新发现1处缺失和5处SNP,共克隆17个不同的gal-3 ORF,其中仅1个克隆与已报告大鼠gal-3 c DNA的ORF完全相同。从1号和3号个体肝脏中分别克隆11和14个不同的gal-3 ORF,揭示大鼠gal-3 c DNA存在个体水平的分子多样性。     

Interaction of a novel cysteine and histidine-rich cytoplasmic protein with galectin-3 in a carbohydrate-independent manner

We have used the yeast two-hybrid system to search for cytoplasmic proteins that might assist in the intracellular trafficking of the soluble beta-galactoside-binding protein, galectin-3. We utilised as bait murine full-length galectin-3 to screen a murine 3T3 cDNA library. Several interacting clones were found to encode a partial open reading frame and a full-length clone was obtained by rapid amplification of cDNA ends methodology. In various assays in vitro the novel protein was shown to bind galectin-3 in a carbohydrate-independent manner. The novel protein contains an unusually high content of cysteine and histidine residues and shows significant sequence homologies with several metal ion-binding motifs present in known proteins. Confocal immunofluorescence microscopy of permeabilised 3T3 cells shows a prominent perinuclear, as well as cytoplasmic, localisation of the novel protein.     

Cytoplasmic and serum galectin-3 in diagnosis of thyroid malignancies

In order to address whether galectin-3 in the sera and fine needle aspirates serve as a diagnostic marker distinguishing between benign and malignant thyroid nodules, we developed an enzyme-linked immunosorbent assay. We quantified galectin-3 in fine needle aspirates from a series of 118 patients with thyroid nodules and serum galectin-3 from another series of 46 patients, which were compared with final histology after thyroidectomy. Relative galectin-3 value (ng/mg), defined as galectin-3 concentration (ng/ml) divided by total protein concentration (mg/ml) in fine needle aspirates, was significantly higher in papillary carcinoma than in the other thyroid entities. There was no significant difference in serum galectin-3 level among patients with thyroid nodules and healthy individuals. Accordingly, relative galectin-3 value allows a definitive diagnosis of papillary carcinoma independent of cellular morphology, whereas serum galectin-3 does not serve as a marker for papillary carcinoma.     

Unilaminar follicular cells transiently express galectin-3 during ovarian folliculogenesis in pigs

The localization of galectin-3, a β-galactoside-binding animal lectin, was immunohistochemically studied in the ovaries of pigs to determine its expression in ovarian folliculogenesis. Various stages of ovarian follicles were identified in the ovaries of adult pigs. Galectin-3 was immunostained in the squamous follicular cells surrounding oocytes in primordial follicles and in the unilaminar granulosa cells of primary follicles, but not in oocytes of multilaminar follicles (including primary, secondary, and tertiary Graafian follicles). As in adult ovaries, galectin-3 immunoreactivity was prominent in the unilaminar follicles in neonatal ovaries. Galectin-3 was also immunolocalized in the luteal cells in the corpus luteum and granulosa cells of atretic follicles as well as in interstitial macrophages in porcine ovaries. Collectively, these results suggest that galectin-3 is transiently expressed in follicular cells in the unilaminar ovarian follicles (primordial and primary) but not in multilaminar ovarian follicles (primary to tertiary), implying that galectin-3 is embryologically involved in ovum generation.     

Engineering of galectin-3 for glycan-binding optical imaging

Galectin-3 (Gal-3) is a multifunctional glycan-binding protein that participates in many pathophysiological events and has been described as a biomarker and potential therapeutic target for severe disorders, such as cancer. Several probes for Gal-3 or its ligands have been developed, however both the pathophysiological mechanisms and potential biomedical applications of Gal-3 remain not fully assessed. Molecular imaging using bioluminescent probes provides great sensitivity for in vivo and in vitro analysis for both cellular and whole multicellular organism tracking and target detection. Here, we engineered a chimeric molecule consisting of Renilla luciferase fused with mouse Gal-3 (RLuc-mGal-3). RLuc-mGal-3 preparation was highly homogenous, soluble, active, and has molecular mass of 65,870.95 Da. This molecule was able to bind to MKN45 cell surface, property which was inhibited by the reduction of Gal-3 ligands on the cell surface by the overexpression of ST6GalNAc-I. In order to obtain an efficient and stable delivery system, RLuc-mGal-3 was adsorbed to poly-lactic acid nanoparticles, which increased binding to MKN45 cells in vitro. Furthermore, bioluminescence imaging showed that RLuc-mGal-3 was able to indicate the presence of implanted tumor in mice, event drastically inhibited by the presence of lactose. This novel bioluminescent chimeric molecule offers a safe and highly sensitive alternative to fluorescent and radiolabeled probes with potential application in biomedical research for a better understanding of the distribution and fate of Gal-3 and its ligands in vitro and in vivo.     

Phosphoinositide 3-kinase-gamma expression is upregulated in brain microglia and contributes to ischemia-induced microglial activation in acute experimental stroke

Microglia, the resident microphages of the CNS, are rapidly activated after ischemic stroke. Inhibition of microglial activation may protect the brain by attenuating blood-brain barrier damage and neuronal apoptosis after ischemic stroke. However, the mechanisms by which microglia is activated following cerebral ischemia is not well defined. In this study, we investigated the expression of PI3Kγ in normal and ischemic brains and found that PI3Kγ mRNA and protein are constitutively expressed in normal brain microvessels, but significantly upregulated in postischemic brain primarily in activated microglia following cerebral ischemia. In vitro, the expression of PI3Kγ mRNA and protein was verified in mouse brain endothelial and microglial cell lines. Importantly, absence of PI3Kγ blocked the early microglia activation (at 4 h) and subsequent expansion (at 24-72 h) in PI3Kγ knockout mice. The results suggest that PI3Kγ is an ischemia-responsive gene in brain microglia and contributes to ischemia-induced microglial activation and expansion.     

Aminopeptidase N/CD13 induces angiogenesis through interaction with a pro-angiogenic protein, galectin-3

Aminopeptidase N/CD13 is an endothelial cell surface ectoenzyme involved in one of the initial steps of angiogenesis. However, little is known how APN induces angiogenesis in endothelial cells. Using human cDNA library-encoding phage display biopanning method, we here identified a galactoside-specific lectin family protein, galectin-3, as an interacting protein of APN. Galectin-3 specifically binds to APN both in vitro and in human umbilical vein endothelial cells (HUVECs) in a carbohydrate recognition-dependent manner. Immunohistochemical analysis demonstrates that both APN and galectin-3 are exclusively coexpressed during the angiogenic stage of mouse forebrain development. Finally, exogenous addition of galectin-3 into HUVECs induced angiogenesis in an APN-dependent manner, implying that APN is a crucial mediator of galectin-3-induced angiogenesis in endothelial cells.     

Use of cocultured cell systems to elucidate chemokine-dependent neuronal/microglial interactions: control of microglial activation

In order to understand processes involved in central nervous system inflammatory diseases, a critical appreciation of mechanisms involved in the control of immune function in the brain is needed. Microglial cells are watchful eyes for unusual events and detecting the presence of pathogens but are also alert to signals emanating from damaged neurons. Fractalkine (CX3CL1) is a chemokine which is expressed predominantly in the central nervous system, being localized on neurons, while its receptor, CX3CR1, is found on microglial cells. We have developed a strategy to investigate the role of this chemokine in neuronal-microglia interactions. Because fractalkine is expressed both as a soluble and as a membrane-attached protein, we have established various protocols involving different levels of cell-to-cell communication. Three experimental systems were instituted, including (1) a conditioned medium transfer system in which no cell-cell communication or contact is possible, (2) a transwell system that permits cell-contact-independent communication through diffusible soluble factors only, and (3) a coculture system allowing cell-to-cell communication via direct microglial-neuronal contacts. Using these in vitro cocultured systems, we have investigated the role of a soluble and/or cell-associated chemokine, such as fractalkine, in order to obtain insights into the role of glia-neuron interactions in cerebral inflammation.     

A role for galectin-3 in CD13-mediated homotypic aggregation of monocytes

We recently reported that anti-CD13 mAbs induce homotypic aggregation of monocytic cells. This phenomenon is signal transduction dependent and does not require CD13 aminopeptidase activity. Since CD13 is heavily glycosylated and a member of the galectin family (galectin-4) has been shown to associate with CD13 in the intestinal epithelium, we hypothesized that CD13-mediated aggregation might proceed through a carbohydrate-dependent mechanism involving galectin-3, the most highly expressed galectin on monocytes. We report here that lactose and anti-galectin-3 antibodies completely abrogate homotypic aggregation induced by anti-CD13 antibodies. Furthermore, galectin-3 co-immunoprecipitates with CD13 from resting U-937 cells and this association decreases during the aggregation process, a phenomenon that may have functional implications. Together, the results presented here point to a key role for galectin-3 in CD13-mediated homotypic aggregation of monocytic cells.     

Anti-oxidant and anti-inflammatory activities of macelignan in murine hippocampal cell line and primary culture of rat microglial cells

Epidemiological studies suggest that the treatments of anti-inflammatory agents and anti-oxidants slow the progress of neurological diseases. Lignans are anti-oxidants and phytoestrogens found in a variety of plants. In this study, we investigated the neuroprotective effect of macelignan on glutamate-induced neurotoxicity and reactive oxygen species (ROS) in murine hippocampal HT22 cell line. Macelignan significantly attenuated the ROS production and neurotoxicity induced by glutamate in HT22 cell. Also, the properties of macelignan as an anti-inflammatory agent were investigated in microglials activation by lipopolysaccharide (LPS). It potently suppressed the expression of cyclooxygenase-2 and inducible nitric oxide synthase, that consequently resulted in the reduction of nitric oxide in LPS-treated microglial cells. It also significantly suppressed the production of pro-inflammatory cytokine tumor necrosis factor-alpha and interleukin-6. These results suggest that macelignan possesses therapeutic potentials against neurodegenerative diseases with oxidative stress and neuroinflammation.     

半乳糖凝集素-3(galectin-3)基因沉默对Eca109人类食管癌细胞的影响

半乳糖凝集素-3(galectin-3)是一种多功能的β-半乳糖苷结合凝集素,涉及包括细胞生长、粘附、增殖、进展、转移以及凋亡等多种生物学功能,在恶性肿瘤中高表达。以前的研究已经证实了galecin-3过表达在Eca109人食管癌细胞的生物学作用。本研究试图通过进行小干扰RNA(siRNA)介导的galectin-3沉默,以分析galectin-3沉默对食管癌细胞生物学行为的影响。我们采用Western blotting和RT-qPCR被用来证实在蛋白质和mRNA水平上的galectin-3低表达,使用细胞计数试剂盒-8评估细胞增殖,用Annexin V-PE/7-AAD细胞凋亡检测试剂盒和流式细胞术检测Eca109细胞的凋亡。研究结果表明,转染后72 h,si Gal-3组Eca109细胞增殖明显低于siRNA对照组和未处理组(p<0.001)。Transwell实验结果显示,与其他组相比,galecin-3的抑制作用显著降低Eca109细胞的迁移和侵袭能力(p<0.05)。与siRNA-对照组和未处理组相比,galectin-3敲低显著增加Eca109细胞的凋亡率(p<0.05)。敲低Eca109细胞中galecin-3的表达后,细胞增殖、迁移和侵袭能力下降,而细胞凋亡增强,说明galectin沉默可作为食管癌治疗的新策略。     

Multifaceted role of galectin-3 on human glioblastoma cell motility

Astrocytic tumors' aggressiveness results from an imbalance between cell proliferation and cell death favoring growth, but also from the propensity of tumor cells to detach from the primary tumor site, migrate, and invade the surrounding parenchyma. Astrocytic tumor progression is known to be associated with an increased expression of galectin-3. We investigated in cell culture how galectin-3 expression affects astrocytoma cell motility. Galectin-3 deficient cells were obtained by stable transfection of the U373 glioblastoma cell line with a specific expression antisense plasmid. Cultured galectin-3 deficient glioblastoma cells showed increased motility potential on laminin and modifications in the cytoskeleton reorganization. In addition, c-DNA microarrays and quantitative immunofluorescence analysis showed that galectin-3 deficient U373 cells have an increased expression of integrins-alpha6 and -beta1, proteins known to be implicated in the regulation of cell adhesion.     

GDNF promotes neurite outgrowth and upregulates galectin-1 through the RET/PI3K signaling in cultured adult rat dorsal root ganglion neurons

Galectin-1 (GAL-1), a member of a family of β-galactoside binding animal lectins, is predominantly expressed in isolectin B4 (IB4)-binding small non-peptidergic (glial cell line-derived neurotrophic factor (GDNF)-responsive) sensory neurons in the sections of adult rat dorsal root ganglia (DRG), but its functional role and the regulatory mechanisms of its expression in the peripheral nervous system remain unclear. In the present study, both recombinant nerve growth factor (NGF) and GDNF (50 ng/ml) promoted neurite outgrowth from cultured adult rat DRG neurons, whereas GDNF, but not NGF, significantly increased the number of IB4-binding neurons and the relative protein expression of GAL-1 in the neuron-enriched culture of DRG. The GAL-1 expression in immortalized adult rat Schwann cells IFRS1 and DRG neuron-IFRS1 cocultures was unaltered by treatment with GDNF, which suggests that GDNF/GAL-1 signaling axis is more related to neurite outgrowth, rather than neuron-Schwann cell interactions. The GDNF-induced neurite outgrowth and GAL-1 upregulation were attenuated by anti-GDNF family receptor (RET) antibody and phosphatidyl inositol-3′-phosphate-kinase (PI3K) inhibitor LY294002, suggesting that the neurite-outgrowth promoting activity of GDNF may be attributable, at least partially, to the upregulation of GAL-1 through RET-PI3K pathway. On the contrary, no significant differences were observed between GAL-1 knockout and wild-type mice in DRG neurite outgrowth in the presence or absence of GDNF. Considerable immunohistochemical colocalization of GAL-3 with GAL-1 in DRG sections and GDNF-induced upregulation of GAL-3 in cultured DRG neurons imply the functional redundancy between these galectins.     

Anti-inflammatory effects of N-cyclooctyl-5-methylthiazol-2-amine hydrobromide on lipopolysaccharide-induced inflammatory response through attenuation of NLRP3 activation in microglial cells

Microglial activation is closely associated with neuroinflammatory pathologies. The nucleotide-binding and oligomerization domain-like receptor containing a pyrin domain 3 (NLRP3) inflammasomes are highly organized intracellular sensors of neuronal alarm signaling. NLRP3 inflammasomes activate nuclear factor kappa-B (NF-κB) and reactive oxygen species (ROS), which induce inflammatory responses. Moreover, NLRP3 dysfunction is a common feature of chronic inflammatory diseases. The present study investigated the effect of a novel thiazol derivative, N-cyclooctyl-5-methylthiazol-2-amine hydrobromide ({"type":"entrez-protein","attrs":{"text":"KHG26700","term_id":"728847257"}}KHG26700), on inflammatory responses in lipopolysaccharide (LPS)-treated BV-2 microglial cells. {"type":"entrez-protein","attrs":{"text":"KHG26700","term_id":"728847257"}}KHG26700 significantly attenuated the expression of several pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and interleukin-6, in these cells, as well as the LPS-induced increases in NLRP3, NF-κB, and phospho-IkBα levels. {"type":"entrez-protein","attrs":{"text":"KHG26700","term_id":"728847257"}}KHG26700 also suppressed the LPS-induced increases in protein levels of autophagy protein 5 (ATG5), microtubule-associated protein 1 light chain 3 (LC3), and beclin-1, as well as downregulating the LPS-enhanced levels of ROS, lipid peroxidation, and nitric oxide. These results suggest that the anti-inflammatory effects of {"type":"entrez-protein","attrs":{"text":"KHG26700","term_id":"728847257"}}KHG26700 may be due, at least in part, to the regulation of the NLRP3-mediated signaling pathway during microglial activation.     

Calpain activation through galectin-3 inhibition sensitizes prostate cancer cells to cisplatin treatment

Prostate cancer will develop chemoresistance following a period of chemotherapy. This is due, in part, to the acquisition of antiapoptotic properties by the cancer cells and, therefore, development of novel strategies for treatment is of critical need. Here, we attempt to clarify the role of the antiapoptotic molecule galectin-3 in prostate cancer cells using siRNA and antagonist approaches. The data showed that Gal-3 inhibition by siRNA or its antagonist GCS-100/modified citrus pectin (MCP) increased cisplatin-induced apoptosis of PC3 cells. Recent studies have indicated that cisplatin-induced apoptosis may be mediated by calpain, a calcium-dependent protease, as its activation leads to cleavage of androgen receptor into an androgen-independent isoform in prostate cancer cells. Thus, we examined whether calpain activation is associated with the Gal-3 function of regulating apoptosis. Here, we report that Gal-3 inhibition by siRNA or GCS-100/MCP enhances calpain activation, whereas Gal-3 overexpression inhibits it. Inhibition of calpain using its inhibitor and/or siRNA attenuated the proapoptotic effect of Gal-3 inhibition, suggesting that calpain activation may be a novel mechanism for the proapoptotic effect of Gal-3 inhibition. Thus, a paradigm shift for treating prostate cancer is suggested whereby a combination of a non-toxic anti-Gal-3 drug together with a toxic chemotherapeutic agent could serve as a novel therapeutic modality for chemoresistant prostate cancers.     

Reconstitution of galectin-3 alters glutathione content and potentiates TRAIL-induced cytotoxicity by dephosphorylation of Akt

We investigated the role of galectin-3 in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptotic death in human breast carcinoma BT549 cells. We observed that parental galectin-3 null BT549 cells (BT549(par)) as well as control vector transfected (BT549(neo)) cells were resistant to TRAIL, while galectin-3 cDNA-transfected BT549 cells (BT549(gal-3)) were sensitive to TRAIL. Data from flow cytometry and immunoblotting analyses reveal that reconstitution of galectin-3 promoted cell death and PARP cleavage as well as caspase (-8, -9, and -3) activation during TRAIL treatment. However, unlike TRAIL treatment, galectin-3 transfectants were resistant to UV-B-induced PARP cleavage. Data from cDNA array analysis show that galectin-3 did not significantly enhance or reduce any apoptosis-related gene expression. Moreover, although galectin-3 restored pre-mRNA splicing activity and resulted in elevation of FLIPs protein, experiments with FLIPs cDNA-transfected cells show that overexpression of FLIPs did not sensitize cells to TRAIL. Interestingly, BT549(gal-3) cells demonstrated a approximately 2-fold increase in total glutathione content as well as a approximately 5-fold increase in GSSG content in comparison to BT549(par) and BT549(neo) cells, suggesting that galectin-3 overexpression may alter intraceullular oxidation/reduction reactions affecting the metabolism of glutathione and other thiols. In addition, galectin-3 overexpression inactivated Akt by dephosphorylation. Finally, overexpression of constitutively activated Akt protected BT549(gal-3) cells from TRAIL-induced cytotoxicity. Taken together, our data suggest that galectin-3-enhanced TRAIL-induced cytotoxicity is mediated through dephosphorylation of Akt, possibly through a redox-dependent process.     

Differential expression of galectins in normal, benign and malignant prostate epithelial cells: silencing of galectin-3 expression in prostate cancer by its promoter methylation

Galectins (gal), a family of soluble beta-galactoside-binding proteins present at the cell surface, are involved in cancer progression and metastasis. Here we investigated the expression of several galectins in normal (PrEC), benign (BPH-1), and malignant (LNCaP) prostate epithelial cells and found that all galectins, except gal1 are differentially expressed. The gal3, 7, and 9 are highly expressed in PrEC, but not in LNCaP cells. Out of seven isoforms of gal8, the proto isoform gal8e and our newly discovered proto isoform gal8g were upregulated in LNCaP cells compared to PrEC, whereas the two tandem-repeat isoforms gal8a and gal8b were equally expressed in these cells. To determine if the silencing of gal3 in LNCaP cells was due to promoter methylation, LNCaP cells were treated with azacytidine. Azacytidine treatment induced the expression of gal3 in LNCaP cells, indicating that the gal3 gene was silenced by methylation of its promoter. To examine further, we evaluated cytosine methylation in gal3 promoter in LNCaP, normal prostate and placenta DNA and observed that it is highly methylated in LNCaP but not in normal cells and azacytidine completely abolished this methylation in LNCaP cells. Similar to prostate cancer cells, gal3 promoter was highly methylated in human prostate cancer tissue but not in normal tissue. To our knowledge, this is the first report indicating that gal3 expression is regulated by promoter methylation in LNCaP cells and prostate tumors. The methylation of gal3 promoter may constitute a powerful tool for early diagnosis of prostate cancer.     

Expression of galectin-3 in the rat pancreas during regeneration following hormone-induced pancreatitis

Supramaximal dosage of the cholecystokinin analog caerulein leads to edematous pancreatitis with subsequent acinar cell destruction predominantly by apoptosis. We have used immunohistochemistry to reveal the expression of the anti-apoptotic protein galectin-3 in pancreatic acinar cells. Galectin-3, which occurs only in duct cells under physiological conditions, is expressed in a subset of acinar cells after the end of a 12-h caerulein infusion, giving rise to a patchy staining pattern. During the subsequent period of inflammation and regeneration, galectin-3 expression increases in those acinar cells that undergo apoptosis. By 48 h after the end of caerulein infusion, morphologically normal cells do not contain galectin-3 and participate in regeneration by proliferation. Tubular complexes, being transient structures from degenerative acini, accumulate galectin-3 in the remnants of the epithelium cells. Stimulation with supramaximal dosages of caerulein of the cell line AR4–2J, which is derived from rat pancreatic acinar cells, also results in a marked increase of galectin-3, confirming the in vivo results. We postulate that the high expression of the anti-apoptotic protein galectin-3 regulates the time course of the apoptotic process in pancreatic acinar cells.