Cellular, Molecular and Clinical Characterization of Patients with Hermansky-Pudlak Syndrome Type 5

Section on Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, Bethesda, MD, USA.
Traffic (Impact Factor: 4.35). 10/2004; 5(9):711-22. DOI: 10.1111/j.1600-0854.2004.00208.x
Source: PubMed


Hermansky-Pudlak syndrome (HPS) is a disorder of lysosome-related organelles such as melanosomes and platelet dense granules. Seven genes are now associated with HPS in humans. An accurate diagnosis of each HPS subtype has important prognostic and treatment implications. Here we describe the cellular, molecular, and clinical aspects of the recently identified HPS-5 subtype. We first analyzed the genomic organization and the RNA expression pattern of HPS5, located on chromosome 11p14, and demonstrated tissue-specific expression of at least three alternatively spliced HPS5 mRNA transcripts, coding for HPS5A and HPS5B proteins, that differ at their 5'-ends. Genetic screening of 15 unassigned HPS patients yielded six new HPS5 mutations in four patients. Clinically, our HPS-5 patients exhibited iris transillumination, variable hair and skin pigmentation, and absent platelet dense bodies, but not pulmonary fibrosis or granulomatous colitis. In two patients with homozygous missense mutations, hemizygosity was ruled out by gene-dosage multiplex polymerase chain reaction, and immunocytochemical analyses of their fibroblasts supported the HPS-5 diagnosis. Specifically, LAMP-3 distribution was restricted to the perinuclear region in HPS-5 fibroblasts, in contrast to the normal LAMP-3 distribution, which extended to the periphery. This specific intracellular vesicle distribution in fibroblasts, in combination with the clinical features, will improve the characterization of the HPS-5 subtype.

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    • "HPS5 (Ruby eye-2) is an ubiquitously expressed protein [71] in vivo related to melanocyte differentiation and eumelanin synthesis [60]. Its absence influences the distribution of CD63 [72], the platelet activation antigen essential for leukocyte recruitment [73]. Hence, upregulation of HPS5 during the greenfinch immune response suggests the genes involvement in linking melanin-based traits and immune function – a concept proposed in vertebrates [74]. "
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    ABSTRACT: Background Immunoecology aims to explain variation among hosts in the strength and efficacy of immunological defences in natural populations. This requires development of biomarkers of the activation of the immune system so that they can be collected non-lethally and sampled from small amounts of easily obtainable tissue. We used transcriptome profiling in wild greenfinches (Carduelis chloris) to detect whole blood transcripts that most profoundly indicate upregulation of antimicrobial defences during acute phase response. The more general aim of this study was to obtain a functional annotation of a substantial portion of the greenfinch transcriptome that would enable to gain access to more specific genomic tools in subsequent studies. The birds received either bacterial lipopolysaccharide or saline injections and RNA-seq transcriptional profiling was performed 12 h after treatment to provide initial functional annotation of the transcriptome and assess whole blood response to immune stimulation. Results A total of 66,084 transcripts were obtained from de novo Trinty assembly, out of which 23,153 could be functionally annotated. Only 1,911 of these were significantly upregulated or downregulated. The manipulation caused marked upregulation of several transcripts related to immune activation. These included avian-specific antimicrobial agents avidin and gallinacin, but also some more general host response genes, such as serum amyloid A protein, lymphocyte antigen 75 and copper-transporting ATPase 1. However, links with avian immunity for most differentially regulated transcripts remained rather hypothetical, as a large set of differentially expressed transcripts lacked functional annotation. Conclusions This appears to be the first large scale transcriptional profiling of immune function in passerine birds. The transcriptomic data obtained suggest novel markers for the assessment of the immunological state of wild passerines. Characterizing the function of those possible novel infection markers would assist future vertebrate genome annotation. The extensive sequence information collected enables to identify possible target and housekeeping genes needed to gain access to more specific genomic tools in future studies. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-533) contains supplementary material, which is available to authorized users.
    Full-text · Article · Jun 2014 · BMC Genomics
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    • "Therefore, these results suggested that patients 88 and 156 suffer from HPS due to mutations causing BLOC-2 deficiency, and that patients 45, 94 and 128 suffer from HPS due to BLOC-3 deficiency. Based on reported differences in the severity of HPS disease caused by BLOC-2 deficiency (in HPS-3, -5 or -6 [8] [11] [29] [30] [31] [32]) or BLOC-3 deficiency (in HPS-1 or -4 [18] [19] [20] [21] [22] [23]), one would then expect that patients 88 and 156 should suffer from a mild form of HPS and that patients 45, 94 and 128 should be at a higher risk of developing pulmonary fibrosis or GI disease. Unfortunately, only two of these patients (88 and 45) were examined at an age in which the validity of these predictions could begin to be evaluated: at the time of their last evaluation at the NIH Clinical Center, patients 88 (age 40 years), 94 (age 2 years), 128 (age 2 years) and 156 (age 19 years) had no signs of interstitial lung disease of GI disease, while patient 45 (age 35 years) presented with a history of GI disease but no interstitial lung disease. "
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    ABSTRACT: Hermansky-Pudlak syndrome (HPS) comprises a constellation of human autosomal recessive disorders characterized by albinism and platelet storage pool deficiency. At least eight types of HPS have been defined based on the identity of the mutated gene. These genes encode components of four ubiquitously expressed protein complexes, named Adaptor Protein (AP)-3 and Biogenesis of Lysosome-related Organelles Complex (BLOC)-1 through -3. In patients of Puerto Rican origin, the molecular diagnosis can be based on analysis of two founder mutations. On the other hand, identification of the HPS type in other patients relies on the sequencing of all candidate genes. In this work, we have developed a biochemical assay to minimize the number of candidate genes to be sequenced per patient. The assay consists of immunoblotting analysis of extracts prepared from skin fibroblasts, using antibodies to one subunit per protein complex. The assay allowed us to determine which complex was defective in each of a group of HPS patients with unknown genetic lesions, thus subsequent sequencing was limited to genes encoding the corresponding subunits. Because no mutations within the two genes encoding BLOC-3 subunits could be found in two patients displaying reduced BLOC-3 levels, the possible existence of additional subunits was considered. Through size-exclusion chromatography and sedimentation velocity analysis, the native molecular mass of BLOC-3 was estimated to be 140+/-30 kDa, a value most consistent with the idea that BLOC-3 is a HPS1HPS4 heterodimer (approximately 156 kDa) albeit not inconsistent with the putative existence of a relatively small third subunit.
    Full-text · Article · Mar 2008 · Molecular Genetics and Metabolism
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    • "The study was conducted according to the Declaration of Helsinki Principles. This HPS-5 patient is compound heterozygous for a frameshift mutation in exon 18 and a nonsense mutation (R865X), resulting in markedly decreased HPS5 RNA on Northern blot (Huizing et al., 2004). "
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    ABSTRACT: Hermansky-Pudlak syndrome (HPS) is a disorder of lysosome-related organelle biogenesis resulting in melanosome dysfunction and absent platelet dense bodies. HPS patients have oculocutaneous albinism, bruising, and bleeding. HPS-5 results from deficiency of the HPS5 protein, a component of the biogenesis of lysosome-related organelles complex-2 (BLOC-2). HPS5 has an unknown function and lacks homology to known proteins. We performed ultrastructural studies of HPS-5 melanocytes revealing predominantly early-stage melanosomes with many small 3,4(OH)2-phenylalanine-positive vesicles throughout the cell body and dendrites. These findings resemble the distinct ultrastructural features of HPS-3 melanocytes; HPS3 is also a BLOC-2 component. Immunofluorescence and immunoEM studies showed decreased TYRP1 labeling in the dendrites of HPS-5 melanocytes, and the overall abundance of TYRP1 was reduced. No substantial differences were observed in the distribution or abundance of Pmel17 in HPS-5 melanocytes. In normal melanocytes, endogenous tyrosinase colocalized with Pmel17 and TYRP1 in the perinuclear area and dendritic tips; this was much reduced in HPS-5 melanocytes, particularly in the tips. We conclude that early stage melanosome formation and Pmel17 trafficking are preserved in HPS5-deficient cells. Tyrosinase and TYRP1 are mistrafficked, however, and fail to be efficiently delivered to melanosomes of HPS-5 melanocytes.
    Full-text · Article · Jul 2007 · Journal of Investigative Dermatology
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