Membrane traffic research: Challenges for the next decade

The study of membrane traffic is now a well-established area of research, and one that has resulted in several Nobel prizes including ones awarded to Albert Claude, George Palade, and Christian DeDuve in 1974, Michael Brown and Joseph Goldstein in 1985, Gunter Blobel in 1999, and most recently James Rothman, Randy Schekman, and Thomas Südhof in 2013. As a result of their studies and other research, we now have fundamental insights into the organization and routes of transport between the cells' membranous organelles. Moreover, we have defined the basic "cellular machinery" that governs protein and lipid synthesis, that ensures selective recognition of proteins and lipids, and that promotes vesicle fission, transport, and fusion. In addition, we have a large number of insights into the regulatory molecules that control these processes including the Rab GTPases and their effectors. While the challenges for the future are many, this essay is focused on areas of investigation that we see as moving forward at a rapid pace, which speak to how membrane traffic contributes to overall cell and tissue function, and which are likely to provide important avenues of funding for both established and new investigators. These challenges include how membrane traffic is regulated in response to metabolic needs, how molecules are transferred between organelles, how membrane traffic is regulated and functions during processes such as development, and how membrane traffic is used by highly differentiated cells to perform specialized cell functions

Episcopal Applicants to Ordained Ministry: Are They Psychological Healthy?

The current investigation evaluated psychological and personality profiles of applicants to the diaconate and priesthood for several Episcopal dioceses. Applicants included both genders and their ages ranged from 29 to 67 years. A psychological testing battery including the MMPI-2, 16PF, and MCMI-III was administered to 42 applicants between 2008 and 2009 who subsequently entered the diaconate or priestly formation program in the Episcopal Church. Results indicate that these applicants were generally well-adjusted. Findings also suggest some tendency for defensiveness, repression, naïveté, and a strong need for affection, as well as for being emotionally stable, intelligent, trusting, and open to change. Finally, results suggest elevations on histrionic, narcissistic, and compulsive measures

The Uroepithelial-associated sensory web

An important, but not well understood, function of epithelial cells is their ability to sense changes in their extracellular environment and then communicate these changes to the underlying nervous, connective, and muscular tissues. This communication is likely to be important for tube- and sac-shaped organs such as blood vessels, the lungs, the gut, and the bladder, whose normal function can be modulated by stimuli initiated within the epithelium. We propose that the uroepithelium, which lines the renal pelvis, ureters, and inner surface of the bladder, functions as an integral part of a ‘sensory web.’ Through uroepithelial-associated channels and receptors, the uroepithelium receives sensory ‘inputs’ such as changes in hydrostatic pressure and binding of mediators including adenosine triphosphate (ATP). These input signals stimulate membrane turnover in the outermost umbrella cell layer and release of sensory ‘outputs’ from the uroepithelium in the form of neurotransmitters and other mediators that communicate changes in the uroepithelial milieu to the underlying tissues, altering their function. The global consequence of this sensory web is the coordinated function of the bladder during the cycles of filling and voiding, and disruption of this web is likely to lead to bladder dysfunction

Requirement for a Uroplakin 3a-like protein in the development of zebrafish pronephric tubule epithelial cell function, morphogenesis, and polarity

Uroplakin (UP)3a is critical for urinary tract development and function; however, its role in these processes is unknown. We examined the function of the UP3a-like protein Upk3l, which was expressed at the apical surfaces of the epithelial cells that line the pronephric tubules (PTs) of the zebrafish pronephros. Embryos treated with upk3l-targeted morpholinos showed decreased pronephros function, which was attributed to defects in PT epithelial cell morphogenesis and polarization including: loss of an apical brush border and associated phospho-ERM proteins, apical redistribution of the basolateral Na+/K+-ATPase, and altered or diminished expression of the apical polarity complex proteins Prkcz (atypical protein kinase C zeta) and Pard3 (Par3). Upk3l missing its C-terminal cytoplasmic domain or containing mutations in conserved tyrosine or proline residues did not rescue, or only partially rescued the effects of Upk3l depletion. Our studies indicate that Upk3l promotes epithelial polarization and morphogenesis, likely by forming or stimulating interactions with cytoplasmic signaling or polarity proteins, and that defects in this process may underlie the pathology observed in UP3a knockout mice or patients with renal abnormalities that result from altered UP3a expression. © 2012 Mitra et al

PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al

TBC1D9B functions as a GTPase-activating protein for Rab11a in polarized MDCK cells

Rab11a is a key modulator of vesicular trafficking processes, but there is limited information about the guanine nucleotide-exchange factors and GTPase-activating proteins (GAPs) that regulate its GTP-GDP cycle. We observed that in the presence of Mg(2+) (2.5 mM), TBC1D9B interacted via its Tre2-Bub2-Cdc16 (TBC) domain with Rab11a, Rab11b, and Rab4a in a nucleotide-dependent manner. However, only Rab11a was a substrate for TBC1D9B-stimulated GTP hydrolysis. At limiting Mg(2+) concentrations (<0.5 mM), Rab8a was an additional substrate for this GAP. In polarized Madin-Darby canine kidney cells, endogenous TBC1D9B colocalized with Rab11a-positive recycling endosomes but less so with EEA1-positive early endosomes, transferrin-positive recycling endosomes, or late endosomes. Overexpression of TBC1D9B, but not an inactive mutant, decreased the rate of basolateral-to-apical IgA transcytosis--a Rab11a-dependent pathway--and shRNA-mediated depletion of TBC1D9B increased the rate of this process. In contrast, TBC1D9B had no effect on two Rab11a-independent pathways--basolateral recycling of the transferrin receptor or degradation of the epidermal growth factor receptor. Finally, expression of TBC1D9B decreased the amount of active Rab11a in the cell and concomitantly disrupted the interaction between Rab11a and its effector, Sec15A. We conclude that TBC1D9B is a Rab11a GAP that regulates basolateral-to-apical transcytosis in polarized MDCK cells

Parental Involvement as a Mediator of Academic Performance Among Special Education Middle School Students

Abstract This study examined parental involvement as a mediator of the academic performance of middle school students with special needs. The study built on the different types of parental involvement theorized by Epstein and colleagues (2002) and studied empirically by SCHOOL COMMUNITY JOURNAL 3

Human Nail Plate Modifications Induced by Onychomycosis : Implications for Topical Therapy

Open Access - This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are creditedConclusions: Onchomycotic nails presented a thicker but more porous barrier, and its eroded intracellular matrix rendered the tissue more permeable to topically applied chemicals when an aqueous vehicle was used.Purpose: Through the characterisation of the human onchomycotic nail plate this study aimed to inform the design of new topical ungual formulations.Methods: The mechanical properties of the human nail were characterised using a Lloyd tensile strength tester. The nail’s density was determined via pycnometry and the nail’s ultrastructure by electron microscopy. Raman spectroscopy analysed the keratin disulphide bonds within the nail and its permeability properties were assessed by quantifying water and rhodamine uptake.Results: Chronic in vivo nail plate infection increased human nailplate thickness (healthy 0.49 ± 0.15 mm; diseased 1.20 ± 0.67 mm), but reduced its tensile strength (healthy 63.7 ± 13.4 MPa; diseased 41.7 ± 5.0 MPa) and density (healthy 1.34 ± 0.01 g/cm3; diseased 1.29 ± 0.00 g/cm3). Onchomycosis caused cell-cell separation, without disrupting the nail disulfide bonds or desmosomes. The diseased and healthy nails showed equivalent water uptake profiles, but the rhodamine penetration was 4-fold higher in the diseased nails using a PBS vehicle and 3 -fold higher in an ethanol/PBS vehicle.Peer reviewe