Localization to Mature Melanosomes by Virtue of Cytoplasmic Dileucine Motifs Is Required for Human OCA2 Function

Oculocutaneous albinism type 2 is caused by defects in the gene OCA2, encoding a pigment cell-specific, 12-transmembrane domain protein with homology to ion permeases. The function of the OCA2 protein remains unknown, and its subcellular localization is under debate. Here, we show that endogenous OCA2 in melanocytic cells rapidly exits the endoplasmic reticulum (ER) and thus does not behave as a resident ER protein. Consistently, exogenously expressed OCA2 localizes within melanocytes to melanosomes, and, like other melanosomal proteins, localizes to lysosomes when expressed in nonpigment cells. Mutagenized OCA2 transgenes stimulate melanin synthesis in OCA2-deficient cells when localized to melanosomes but not when specifically retained in the ER, contradicting a proposed primary function for OCA2 in the ER. Steady-state melanosomal localization requires a conserved consensus acidic dileucine-based sorting motif within the cytoplasmic N-terminal region of OCA2. A second dileucine signal within this region confers steady-state lysosomal localization in melanocytes, suggesting that OCA2 might traverse multiple sequential or parallel trafficking routes. The two dileucine signals physically interact in a differential manner with cytoplasmic adaptors known to function in trafficking other proteins to melanosomes. We conclude that OCA2 is targeted to and functions within melanosomes but that residence within melanosomes may be regulated by secondary or alternative targeting to lysosomes.

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Functional characterization of thousands of type 2 diabetes-associated and chromatin-modulating variants under steady state and endoplasmic reticulum stress

10.1101/2020.02.12.939348 ◽

2020 ◽

Cited By ~ 1

Author(s):

Shubham Khetan ◽

Susan Kales ◽

Romy Kursawe ◽

Alexandria Jillette ◽

Steven K. Reilly ◽

...

Keyword(s):

Type 2 Diabetes ◽

Endoplasmic Reticulum ◽

Steady State ◽

Er Stress ◽

Transcriptional Activity ◽

Chromatin Accessibility ◽

Stress Conditions ◽

Gwas Snps

AbstractA major goal in functional genomics and complex disease genetics is to identify functional cis-regulatory elements (CREs) and single nucleotide polymorphisms (SNPs) altering CRE activity in disease-relevant cell types and environmental conditions. We tested >13,000 sequences containing each allele of 6,628 SNPs associated with altered in vivo chromatin accessibility in human islets and/or type 2 diabetes risk (T2D GWAS SNPs) for transcriptional activity in ß cell under steady state and endoplasmic reticulum (ER) stress conditions using the massively parallel reporter assay (MPRA). Approximately 30% (n=1,983) of putative CREs were active in at least one condition. SNP allelic effects on in vitro MPRA activity strongly correlated with their effects on in vivo islet chromatin accessibility (Pearson r=0.52), i.e., alleles associated with increased chromatin accessibility exhibited higher MPRA activity. Importantly, MPRA identified 220/2500 T2D GWAS SNPs, representing 104 distinct association signals, that significantly altered transcriptional activity in ß cells. This study has thus identified functional ß cell transcription-activating sequences with in vivo relevance, uncovered regulatory features that modulate transcriptional activity in ß cells under steady state and ER stress conditions, and substantially expanded the set of putative functional variants that modulate transcriptional activity in ß cells from thousands of genetically-linked T2D GWAS SNPs.

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Mutations in a Novel Gene, Encoding a Single Transmembrane Domain Protein Are Associated with Familial Glucocorticoid Deficiency Type 2

Endocrine Research ◽

10.1081/erc-200044136 ◽

2004 ◽

Vol 30 (4) ◽

pp. 889-890 ◽

Cited By ~ 1

Author(s):

Louise A. Metherell ◽

Sadani Cooray ◽

Angela Huebner ◽

Franz Ruschendorf ◽

Danielle Naville ◽

...

Keyword(s):

Transmembrane Domain ◽

Gene Encoding ◽

Novel Gene ◽

Domain Protein ◽

Glucocorticoid Deficiency ◽

Deficiency Type

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Dysferlin Domain-containing Proteins, Pex30p and Pex31p, Localized to Two Compartments, Control the Number and Size of Oleate-induced Peroxisomes in Pichia pastoris

Molecular Biology of the Cell ◽

10.1091/mbc.e07-10-1042 ◽

2008 ◽

Vol 19 (3) ◽

pp. 885-898 ◽

Cited By ~ 54

Author(s):

Mingda Yan ◽

Dorian A. Rachubinski ◽

Saurabh Joshi ◽

Richard A. Rachubinski ◽

Suresh Subramani

Keyword(s):

Saccharomyces Cerevisiae ◽

Endoplasmic Reticulum ◽

Steady State ◽

Pichia Pastoris ◽

Subcellular Localization ◽

Yarrowia Lipolytica ◽

Dependent Manner ◽

Growth Environment ◽

Dual Localization

Yarrowia lipolytica Pex23p and Saccharomyces cerevisiae Pex30p, Pex31p, and Pex32p comprise a family of dysferlin domain–containing peroxins. We show that the deletion of their Pichia pastoris homologues, PEX30 and PEX31, does not affect the function or division of methanol-induced peroxisomes but results in fewer and enlarged, functional, oleate-induced peroxisomes. Synthesis of Pex30p is constitutive, whereas that of Pex31p is oleate-induced but at a much lower level relative to Pex30p. Pex30p interacts with Pex31p and is required for its stability. At steady state, both Pex30p and Pex31p exhibit a dual localization to the endoplasmic reticulum (ER) and peroxisomes. However, Pex30p is localized mostly to the ER, whereas Pex31p is predominantly on peroxisomes. Consistent with ER-to-peroxisome trafficking of these proteins, Pex30p accumulates on peroxisomes upon overexpression of Pex31p. Additionally, Pex31p colocalizes with Pex30p at the ER in pex19Δ cells and can be chased from the ER to peroxisomes in a Pex19p-dependent manner. The dysferlin domains of Pex30p and Pex31p, which are dispensable for their interaction, stability, and subcellular localization, are essential for normal peroxisome number and size. The growth environment-specific role of these peroxins, their dual localization, and the function of their dysferlin domains provide novel insights into peroxisome morphogenesis.

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Faculty Opinions recommendation of Mutations in a novel gene, encoding a single transmembrane domain protein are associated with familial glucocorticoid deficiency type 2.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1024060.285860 ◽

2005 ◽

Author(s):

Isaac Kohane

Keyword(s):

Transmembrane Domain ◽

Gene Encoding ◽

Novel Gene ◽

Domain Protein ◽

Glucocorticoid Deficiency ◽

Deficiency Type

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Faculty Opinions recommendation of Endoplasmic reticulum stress links obesity, insulin action, and type 2 diabetes.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1021753.251722 ◽

2004 ◽

Author(s):

Andrius Kazlauskas

Keyword(s):

Type 2 Diabetes ◽

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Insulin Action

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Gene Variation of Endoplasmic Reticulum Aminopeptidase 1 and Risk of Incident Type 2 Diabetes Mellitus amongst 22,718 Initially Healthy Women

Clinical Immunology Endocrine & Metabolic Drugs ◽

10.2174/2212707004666170529074731 ◽

2018 ◽

Vol 4 (1) ◽

Author(s):

Jose R. Romero ◽

Paul M Ridker ◽

Daniel I. Chasman ◽

Robert Y.L. Zee

Keyword(s):

Diabetes Mellitus ◽

Type 2 Diabetes ◽

Endoplasmic Reticulum ◽

Type 2 Diabetes Mellitus ◽

Incident Type ◽

Gene Variation ◽

Healthy Women ◽

Incident Type 2 Diabetes ◽

Endoplasmic Reticulum Aminopeptidase 1

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Synthesis, subcellular localization and VP16 interaction of the herpes simplex virus type 2 UL46 gene product

Archives of Virology ◽

10.1007/s007050070045 ◽

2000 ◽

Vol 145 (10) ◽

pp. 2149-2162 ◽

Cited By ~ 37

Author(s):

K. Kato ◽

T. Daikoku ◽

F. Goshima ◽

H. Kume ◽

K. Yamaki ◽

...

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Subcellular Localization ◽

Gene Product ◽

Virus Type ◽

Herpes Simplex Virus Type ◽

Simplex Virus ◽

Ul46 Gene

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Prohibitin: A Novel Molecular Player in KDEL Receptor Signalling

BioMed Research International ◽

10.1155/2015/319454 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13 ◽

Cited By ~ 8

Author(s):

Monica Giannotta ◽

Giorgia Fragassi ◽

Antonio Tamburro ◽

Capone Vanessa ◽

Alberto Luini ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Golgi Complex ◽

Membrane Trafficking ◽

Transmembrane Domain ◽

Cell Cycle Control ◽

Retrograde Transport ◽

Multifunctional Protein ◽

G Protein Coupled ◽

Kdel Receptor ◽

Prohibitin 1

The KDEL receptor (KDELR) is a seven-transmembrane-domain protein involved in retrograde transport of protein chaperones from the Golgi complex to the endoplasmic reticulum. Our recent findings have shown that the Golgi-localised KDELR acts as a functional G-protein-coupled receptor by binding to and activating Gs and Gq. These G proteins induce activation of PKA and Src and regulate retrograde and anterograde Golgi trafficking. Here we used an integrated coimmunoprecipitation and mass spectrometry approach to identify prohibitin-1 (PHB) as a KDELR interactor. PHB is a multifunctional protein that is involved in signal transduction, cell-cycle control, and stabilisation of mitochondrial proteins. We provide evidence that depletion of PHB induces intense membrane-trafficking activity at the ER–Golgi interface, as revealed by formation of GM130-positive Golgi tubules, and recruitment of p115,β-COP, and GBF1 to the Golgi complex. There is also massive recruitment of SEC31 to endoplasmic-reticulum exit sites. Furthermore, absence of PHB decreases the levels of the Golgi-localised KDELR, thus preventing KDELR-dependent activation of Golgi-Src and inhibiting Golgi-to-plasma-membrane transport of VSVG. We propose a model whereby in analogy to previous findings (e.g., the RAS-RAF signalling pathway), PHB can act as a signalling scaffold protein to assist in KDELR-dependent Src activation.

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Drug Interactions with Warfarin: Studies with Dichloralphenazone, Chloral Hydrate and Phenazone (Antipyrine)

Clinical Science ◽

10.1042/cs0400351 ◽

1971 ◽

Vol 40 (4) ◽

pp. 351-364 ◽

Cited By ~ 40

Author(s):

A. Breckenridge ◽

M. L'E. Orme ◽

S. Thorgeirsson ◽

D. S. Davies ◽

R. V. Brooks

Keyword(s):

Endoplasmic Reticulum ◽

Steady State ◽

Urinary Excretion ◽

Binding Sites ◽

Half Life ◽

Chloral Hydrate ◽

Maximal Velocity ◽

Protein Binding Sites ◽

Drug Oxidation ◽

State Plasma

1. Administration of dichloralphenazone, a complex of chloral hydrate and phenazone (antipyrine) caused a fall in steady-state plasma warfarin concentration and loss of anticoagulant control in five subjects. 2. This effect of dichloralphenazone is due to stimulation of the drug-oxidizing enzymes of the liver endoplasmic reticulum by antipyrine, the non-hypnotic part of the complex. Administration of antipyrine caused a fall in steady-state plasma warfarin concentration in five subjects, a shortening of the plasma warfarin half-life, with increased urinary excretion of the metabolites of 14C-labelled warfarin in two subjects and increased urinary excretion of 6β-hydroxycortisol which is formed in the liver endoplasmic reticulum. 3. Administration of chloral hydrate, the hypnotic part of dichloralphenazone, caused no change in anticoagulant control but a fall in steady-state plasma warfarin concentration in five subjects. This is due to the accumulation of trichloroacetic acid which displaces warfarin from plasma protein binding sites. 4. Individual differences in the extent of enzyme induction have been shown to be related to the subjects' rates of drug oxidation. 5. In the rat administration of dichloralphenazone and antipyrine, but not chloral hydrate, caused shortening of pentobarbitone sleeping time and of the plasma [14C]pentobarbitone half-life, shortening of the zoxazolamine paralysis time and increase in the maximal velocity of N-demethylation of ethylmorphine.

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