Rab3D and Actin Reveal Distinct Lamellar Body Subpopulations in Alveolar Epithelial Type II Cells

Weeren, Laura van; Graaff, Anko M. de; Jamieson, James D.; Batenburg, Joseph J.; Valentijn, Jack A.

doi:10.1165/rcmb.2003-0264oc

Cited by 40 publications

(39 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although we did not measure granule size in the present study, the increase in amylase levels we observed in AR42J cells overexpressing mycRab3Dwt may be a result of an increase in granule size and/or number. Others have demonstrated that Rab3D is associated with subpopulations of secretory granules [20,37] and is actually shed from granule membranes prior to exocytosis [19]. Valentijn et al [19] found that pancreatic granules engaging in exocytosis were coated with actin while Rab3D was released from the granule membrane.…”

Section: Discussionmentioning

confidence: 99%

Rab3D regulates amylase levels, not agonist-induced amylase release, in AR42J cells

Limi

Ojakian

Raffaniello

2012

Cellular and Molecular Biology Letters

View full text Add to dashboard Cite

Rab3D is a low molecular weight GTP-binding protein that associates with secretory granules in exocrine cells. AR42J cells are derived from rat pancreatic exocrine tumor cells and develop an acinar cell-like phenotype when treated with dexamethasone (Dex). In the present study, we examined the role of Rab3D in Dex-treated AR42J cells. Rab3D expression and localization were analyzed by subcellular fractionation and immunoblotting. The role of Rab3D was examined by overexpressing myc-labeled wild-type-Rab3D and a constitutively active form of Rab3D (Rab3D-Q81L) in AR42J cells. We found that Rab3D is predominantly membrane-associated in AR42J cells and co-localizes with zymogen granules (ZG). Following CCK-8-induced exocytosis, amylase-positive ZGs appeared to move towards the periphery of the cell and co-localization between Rab3D and amylase was less complete when compared to basal conditions. Overexpression of WT, but not mutant Rab3D, resulted in an increase in cellular amylase levels. Overexpression of mutant and WT Rab3D did not affect granule morphology, CCK-8-induced secretion, longterm (48 hr) basal amylase release or granule density. We conclude that Rab3D is not involved in agonist-induced exocytosis in AR42J cells. Instead, Rab3D may regulate amylase content in these cells.

show abstract

Section: Discussionmentioning

confidence: 99%

Rab3D regulates amylase levels, not agonist-induced amylase release, in AR42J cells

Limi

Ojakian

Raffaniello

2012

Cellular and Molecular Biology Letters

View full text Add to dashboard Cite

show abstract

“…Hence, it is conceivable that secretion of surfactant is not merely a passive process, but requires additional mechanisms to be effective. Almost three decades ago, transmission electron micrographs of fused LBs suggested that actin is involved in expulsion (Tsilibary and Williams, 1983a;Tsilibary and Williams, 1983b) and immunostaining experiments confirmed that F-actin encloses individual LBs in proximity to the PM (van Weeren et al, 2004). We have recently shown that LBs are coated with actin following fusion with the PM (Miklavc et al, 2009b).…”

Section: Introductionmentioning

confidence: 92%

Actin coating and compression of fused secretory vesicles are essential for surfactant secretion: a role for Rho, formins and myosin II

Miklavc¹,

Hecht²,

Hobi³

et al. 2012

Journal of Cell Science

130

View full text Add to dashboard Cite

SummarySecretion of vesicular contents by exocytosis is a fundamental cellular process. Increasing evidence suggests that post-fusion events play an important role in determining the composition and quantity of the secretory output. In particular, regulation of fusion pore dilation and closure is considered a key regulator of the post-fusion phase. However, depending on the nature of the cargo, additional mechanisms might be essential to facilitate effective release. We have recently described that in alveolar type II (ATII) cells, lamellar bodies (LBs), which are secretory vesicles that store lung surfactant, are coated with actin following fusion with the plasma membrane. Surfactant, a lipoprotein complex, does not readily diffuse out of fused LBs following opening and dilation of the fusion pore. Using fluorescence microscopy, atomic force microscopy and biochemical assays, we present evidence that actin coating and subsequent contraction of the actin coat is essential to facilitate surfactant secretion. Latrunculin B prevents actin coating of fused LBs and inhibits surfactant secretion almost completely. Simultaneous imaging of the vesicle membrane and the actin coat revealed that contraction of the actin coat compresses the vesicle following fusion. This leads to active extrusion of vesicle contents. Initial actin coating of fused vesicles is dependent on activation of Rho and formin-dependent actin nucleation. Actin coat contraction is facilitated by myosin II. In summary, our data suggest that fusion pore opening and dilation itself is not sufficient for release of bulky vesicle cargos and that active extrusion mechanisms are required.

show abstract

“…Loss of Rab27B function results in abnormal lung epithelium structure in mice, characterized by atrophy (Bolasco et al, 2011). Rab3D has been detected in type 2 alveolar pneumocytes, although its precise function remains unknown (van Weeren et al, 2004).…”

Section: Rab27b Expression and Localization 365mentioning

confidence: 99%

An immunohistochemical analysis of Rab27B distribution in fetal and adult tissue

Hendrix¹,

Lambein²,

Westbroek³

et al. 2012

Int. J. Dev. Biol.

View full text Add to dashboard Cite

Regulated secretory pathways coordinated by small Rab GTPases are critically involved in intercellular communications. Here, we report the expression and localization of Rab27B in developing and differentiated epithelial human tissues by immunohistochemistry. Rab27B is poorly expressed in fetal tissues suggesting that several developmental mechanisms involved in epithelial differentiation and functions are mediated by other secretory Rab GTPases, such as Rab27A or Rab3 family members. In adult tissues, Rab27B is expressed in a wide variety of differentiated secretory epithelial cells, including those lining the salivary gland, gastrointestinal, mammary and prostate tracts. The complex pattern of Rab27B expression indicates that dysregulation of Rab27B-mediated secretion may have profound implications for disease pathology.

show abstract

Rab3D and Actin Reveal Distinct Lamellar Body Subpopulations in Alveolar Epithelial Type II Cells

Cited by 40 publications

References 32 publications

Rab3D regulates amylase levels, not agonist-induced amylase release, in AR42J cells

Rab3D regulates amylase levels, not agonist-induced amylase release, in AR42J cells

Actin coating and compression of fused secretory vesicles are essential for surfactant secretion: a role for Rho, formins and myosin II

An immunohistochemical analysis of Rab27B distribution in fetal and adult tissue

Contact Info

Product

Resources

About