Role of the microtubule cytoskeleton in traffic of EGF through the lacrimal acinar cell endomembrane network

Insufficient Cumulus Expansion and Poor Oocyte Retrieval in Endometriosis-Related Infertile Women

Endometriosis (EMs) is a common cause for female infertility, leading to the need for in vitro fertilization (IVF). In clinics, we found the operative oocyte retrieval to be more or less difficult in women with EMs. We hypothesized that EMs may be involved in the insufficient cumulus expansion that partially explained the lower oocyte retrieval in EMs-related infertile women undergoing assisted reproductive technology (ART). To explore whether the insufficient cumulus expansion exists in EMs-related infertile women and whether there is a possible relationship between the insufficient cumulus expansion and the clinical phenomenon of difficulty in oocyte retrieval. Those infertile women undergoing IVF recorded in our database between January 2013 and October 2017 were included. The expression levels of cumulus expansion-related genes (HAS2/PTGS2/PTX3/TNFAIP6) in the cumulus cells (CCs) from 19 infertile women with EMs and 24 controls were analyzed by real-time PCR. After that, 635 women with EMs-associated infertility (the EMs group) and 4634 women with male factor-associated infertility (the control group) were included in the retrospective analysis. The clinical outcomes were compared between the two groups. The relative mRNA levels of cumulus expansion-related genes were significantly decreased in the CCs from those infertile women with EMs when compared to the control group (all p < 0.05), especially the expression of PTGS2. The mean oocyte retrieval rates (proportion of obtained oocytes in punctured follicles) were (76.33 ± 2.58)% and (71.80 ± 0.58)% (p < 0.01). The mean numbers of flushing times per follicle were 1.11 ± 0.65 and 3.86 ± 1.53 (p < 0.001). The lower expression of cumulus expansion-related genes in CCs suggests the insufficient cumulus expansion in EMs-related infertile women, which partially explains a possible mechanism related to poor oocyte retrieval.

Use of nucleofection to efficiently transfect primary rabbit lacrimal gland acinar cells

Lacrimal gland acinar cells are an important cell type to study due to their role in production and release of tear proteins, a function essential for ocular surface integrity and normal visual acuity. However, mechanistic studies are often limited by problems with transfection using either plasmid DNA or siRNA. Although various gene delivery methods are available, many have been unproductive due to consistently low transfection efficiencies. We have developed a method using nucleofection that can result in 50% transfection efficiency and 60% knockdown efficiency for plasmid DNA and siRNA, respectively. These results are vastly improved relative to previous studies, demonstrating that nucleofection offers an efficient transfection technique for primary lacrimal gland acinar cells.

Transduced viral IL-10 is exocytosed from lacrimal acinar secretory vesicles in a myosin-dependent manner in response to carbachol

The purpose of this study was to determine the intracellular trafficking and release pathways for the therapeutic protein, viral IL-10 (vIL-10), from transduced acinar epithelial cells from rabbit lacrimal gland. Primary cultured rabbit lacrimal gland acinar cells (LGACs) were transduced with adenovirus serotype 5 containing viral interleukin-10 (AdvIL-10). The distribution of vIL-10 was assessed by confocal fluorescence microscopy. Carbachol (CCH)-stimulated release of vIL-10 was quantified by ELISA. vIL-10 localization and exocytosis was probed in response to treatments with agents modulating actin- and myosin-based transport. vIL-10 immunoreactivity was detected in large intracellular vesicles in transduced LGAC. vIL-10 was partially co-localized with biosynthetic but not endosomal compartment markers. vIL-10 release was sensitive to CCH, and the kinetics of release showed an initial burst phase that was similar but not identical to that of the secretory protein, beta-hexosaminidase. Disassembly of actin filaments with latrunculin B significantly increased CCH-stimulated vIL-10 secretion, suggesting that vIL-10 was released from stores sequestered beneath the subapical actin barrier. That release required the activity of actin-dependent myosin motors previously implicated in secretory vesicle exocytosis was confirmed by findings that CCH-stimulated vIL-10 release was reduced by inhibition of non-muscle myosin 2 and myosin 5c function, using ML-7 and overexpression of dominant negative myosin 5c, respectively. These results suggest that the majority of vIL-10 transgene product is packaged into a subpopulation of secretory vesicles that utilize actin-dependent myosin motors for aspects of actin coat assembly, compound fusion and exocytosis at the apical plasma membrane in response to CCH stimulation.

Novel fiber-dependent entry mechanism for adenovirus serotype 5 in lacrimal acini

The established mechanism for infection of most cells with adenovirus serotype 5 (Ad5) involves fiber capsid protein binding to coxsackievirus-adenovirus receptor (CAR) at the cell surface, followed by penton base capsid protein binding to alpha(v) integrins, which triggers clathrin-mediated endocytosis of the virus. Here we determined the identity of the capsid proteins responsible for mediating Ad5 entry into the acinar epithelial cells of the lacrimal gland. Ad5 transduction of primary rabbit lacrimal acinar cells was inhibited by excess Ad5 fiber or knob (terminal region of the fiber) but not excess penton base. Investigation of the interactions of recombinant Ad5 penton base, fiber, and knob with lacrimal acini revealed that the penton base capsid protein remained surface associated, while the knob domain of the fiber capsid protein was rapidly internalized. Introduction of rabbit CAR-specific small interfering RNA (siRNA) into lacrimal acini under conditions that reduced intracellular CAR mRNA significantly inhibited Ad5 transduction, in contrast to a control (nonspecific) siRNA. Preincubation of Ad5 with excess heparin or pretreatment of acini with a heparinase cocktail each inhibited Ad5 transduction by a separate and apparently additive mechanism. Functional and imaging studies revealed that Ad5, fiber, and knob, but not penton base, stimulated macropinocytosis in acini and that inhibition of macropinocytosis significantly reduced Ad5 transduction of acini. However, inhibition of macropinocytosis did not reduce Ad5 uptake. We propose that internalization of Ad5 into lacrimal acini is through a novel fiber-dependent mechanism that includes CAR and heparan sulfate glycosaminoglycans and that the subsequent intracellular trafficking of Ad5 is enhanced by fiber-induced macropinocytosis.

Accumulation of catalytically active proteases in lacrimal gland acinar cell endosomes during chronic ex vivo muscarinic receptor stimulation

Chronic muscarinic stimulation induces functional quiescence (Scand J Immunol 2003;58:550-65) and alters the traffic of immature cathepsin B (Exp Eye Res 2004;79:665-75) in lacrimal acinar cells. To test whether active proteases aberrantly accumulate in the endosomes, cell samples were cultured 20 h with and without 10-microm carbachol (CCh), incubated with [125I]-bovine serum albumin and then lysed and analysed by subcellular fractionation. CCh decreased total cysteine protease and cathepsin S activities in the isolated lysosome, redistributing them to early endocytic and biosynthetic compartments. CCh decreased [125I] accumulation in all compartments of cells loaded in the absence of protease inhibitors; the cysteine protease inhibitor, leupeptin, prevented the endosomal decrease but not the lysosomal decrease. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and autoradiography demonstrated [125I]-labelled proteolytic products in endomembrane compartments of both control and CCh-stimulated cells, even in the presence of leupeptin, but analysis indicated that CCh increased the amount in endosomes. Two-dimensional fractionation analyses suggest that the CCh-induced redistributions result from blocks in traffic to the late endosome from both the early endosome and the trans-Golgi network. Therefore, we conjecture that chronic muscarinic acetylcholine receptor stimulation leads to aberrant proteolytic processing of autoantigens in endosomes, from whence previously cryptic epitopes may be secreted to the underlying interstitial space.

Altered traffic to the lysosome in an ex vivo lacrimal acinar cell model for chronic muscarinic receptor stimulation

Evidence suggests that lacrimal and salivary epithelial cells constitutively expose potentially pathogenic autoantigens, but that active regulatory networks normally suppress pathological autoimmune responses . Events that potentially disrupt the regulatory networks include increased exposure of constitutive autoantigens and induced exposure of previously cryptic autoantigen epitopes. Chronic muscarinic receptor (MAChR) stimulation in an ex vivo rabbit lacrimal acinar cell model induces functional and biochemical alterations reminiscent of the functional quiescence associated with Sjogren's syndrome . Chronic MAChR stimulation also elicits changes in the compartmental distribution of beta-hexosaminidase, a product that normally is dually targeted into the lysosomal pathway and the regulated apical secretory pathway. Here, we use subcellular fractionation analyses to further explore the nature of the stimulation-induced traffic changes and to identify effectors that might mediate this change. Overnight stimulation of primary cultured rabbit lacrimal gland acinar cells with 10 microM carbachol (CCh) significantly decreased the abundance of mature cathepsin B in the pre-lysosome and lysosome; decreased the abundance of preprocathepsin B in fractions containing the TGN and late endosome; increased the abundance of procathepsin B in fractions containing the basal-lateral membrane; and increased the accumulation of endocytosed [(125)I]-EGF in the recycling endosome. Alterations in distribution or abundance of traffic effectors included: increased abundances of rab5A and rab6 in the TGN; decreased overall abundance of gamma-adaptin; remarkably increased relative abundance of membrane phase-associated actin; redistribution of cytoplasmic dynein from biosynthetic and proximal endocytic compartments to the lysosome; and redistribution of p150(Glued) from the lysosome to biosynthetic or proximal endocytic compartments. We conclude that chronic MAChR stimulation blocks traffic from the early endosome and the TGN to the lysosome, causing lysosomal proteins to reflux to the TGN, endosomes, and basal-lateral membrane. These traffic alterations may be mediated through action on one or more of the effectors noted.