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The retinal pigmentation pathway in human albinism: Not so black and white. Prog Retin Eye Res 2022; 91:101091. [PMID: 35729001 DOI: 10.1016/j.preteyeres.2022.101091] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/24/2022] [Accepted: 05/26/2022] [Indexed: 12/16/2022]
Abstract
Albinism is a pigment disorder affecting eye, skin and/or hair. Patients usually have decreased melanin in affected tissues and suffer from severe visual abnormalities, including foveal hypoplasia and chiasmal misrouting. Combining our data with those of the literature, we propose a single functional genetic retinal signalling pathway that includes all 22 currently known human albinism disease genes. We hypothesise that defects affecting the genesis or function of different intra-cellular organelles, including melanosomes, cause syndromic forms of albinism (Hermansky-Pudlak (HPS) and Chediak-Higashi syndrome (CHS)). We put forward that specific melanosome impairments cause different forms of oculocutaneous albinism (OCA1-8). Further, we incorporate GPR143 that has been implicated in ocular albinism (OA1), characterised by a phenotype limited to the eye. Finally, we include the SLC38A8-associated disorder FHONDA that causes an even more restricted "albinism-related" ocular phenotype with foveal hypoplasia and chiasmal misrouting but without pigmentation defects. We propose the following retinal pigmentation pathway, with increasingly specific genetic and cellular defects causing an increasingly specific ocular phenotype: (HPS1-11/CHS: syndromic forms of albinism)-(OCA1-8: OCA)-(GPR143: OA1)-(SLC38A8: FHONDA). Beyond disease genes involvement, we also evaluate a range of (candidate) regulatory and signalling mechanisms affecting the activity of the pathway in retinal development, retinal pigmentation and albinism. We further suggest that the proposed pigmentation pathway is also involved in other retinal disorders, such as age-related macular degeneration. The hypotheses put forward in this report provide a framework for further systematic studies in albinism and melanin pigmentation disorders.
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Imani J, Bodine SPM, Lamattina AM, Ma DD, Shrestha S, Maynard DM, Bishop K, Nwokeji A, Malicdan MCV, Testa LC, Sood R, Stump B, Rosas IO, Perrella MA, Handin R, Young LR, Gochuico BR, El-Chemaly S. Dysregulated myosin in Hermansky-Pudlak syndrome lung fibroblasts is associated with increased cell motility. Respir Res 2022; 23:167. [PMID: 35739508 PMCID: PMC9229912 DOI: 10.1186/s12931-022-02083-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 06/11/2022] [Indexed: 12/03/2022] Open
Abstract
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by improper biogenesis of lysosome-related organelles (LROs). Lung fibrosis is the leading cause of death among adults with HPS-1 and HPS-4 genetic types, which are associated with defects in the biogenesis of lysosome-related organelles complex-3 (BLOC-3), a guanine exchange factor (GEF) for a small GTPase, Rab32. LROs are not ubiquitously present in all cell types, and specific cells utilize LROs to accomplish dedicated functions. Fibroblasts are not known to contain LROs, and the function of BLOC-3 in fibroblasts is unclear. Here, we report that lung fibroblasts isolated from patients with HPS-1 have increased migration capacity. Silencing HPS-1 in normal lung fibroblasts similarly leads to increased migration. We also show that the increased migration is driven by elevated levels of Myosin IIB. Silencing HPS1 or RAB32 in normal lung fibroblasts leads to increased MYOSIN IIB levels. MYOSIN IIB is downstream of p38-MAPK, which is a known target of angiotensin receptor signaling. Treatment with losartan, an angiotensin receptor inhibitor, decreases MYOSIN IIB levels and impedes HPS lung fibroblast migration in vitro. Furthermore, pharmacologic inhibition of angiotensin receptor with losartan seemed to decrease migration of HPS lung fibroblasts in vivo in a zebrafish xenotransplantation model. Taken together, we demonstrate that BLOC-3 plays an important role in MYOSIN IIB regulation within lung fibroblasts and contributes to fibroblast migration.
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Affiliation(s)
- Jewel Imani
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA
| | | | - Anthony M Lamattina
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA
| | - Diane D Ma
- Division of Hematology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Shikshya Shrestha
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA
| | - Dawn M Maynard
- Medical Genetics Branch, NHGRI, NIH, Bethesda, MD, 20892, USA
| | - Kevin Bishop
- Zebrafish Core Facility, NHGRI, NIH, Bethesda, MD, 20892, USA
| | - Arinze Nwokeji
- Division of Hematology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - May Christine V Malicdan
- NIH Undiagnosed Diseases Program, Common Fund, Office of the Director, NIH, Bethesda, MD, 20892, USA
| | - Lauren C Testa
- Medical Genetics Branch, NHGRI, NIH, Bethesda, MD, 20892, USA
| | - Raman Sood
- Zebrafish Core Facility, NHGRI, NIH, Bethesda, MD, 20892, USA
| | - Benjamin Stump
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA
| | - Ivan O Rosas
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA
| | - Mark A Perrella
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.,Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Robert Handin
- Division of Hematology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Lisa R Young
- Division of Pulmonary and Sleep Medicine, The Children's Hospital of Philadelphia, Perlman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | | | - Souheil El-Chemaly
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.
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Summer R, Krishna R, Schriner D, Cuevas-Mora K, Sales D, Para R, Roman J, Nieweld C, Gochuico BR, Romero F. Matrix metalloproteinase activity in the lung is increased in Hermansky-Pudlak syndrome. Orphanet J Rare Dis 2019; 14:162. [PMID: 31272455 PMCID: PMC6610946 DOI: 10.1186/s13023-019-1143-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/25/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by oculocutaneous albinism and platelet dysfunction and can sometimes lead to a highly aggressive form of pulmonary fibrosis that mimics the fatal lung condition called idiopathic pulmonary fibrosis (IPF). Although the activities of various matrix metalloproteinases (MMPs) are known to be dysregulated in IPF, it remains to be determined whether similar changes in these enzymes can be detected in HPS. RESULTS Here, we show that transcript and protein levels as well as enzymatic activities of MMP-2 and -9 are markedly increased in the lungs of mice carrying the HPS Ap3b1 gene mutation. Moreover, immunohistochemical staining localized this increase in MMP expression to the distal pulmonary epithelium, and shRNA knockdown of the Ap3b1 gene in cultured lung epithelial cells resulted in a similar upregulation in MMP-2 and -9 expression. Mechanistically, we found that upregulation in MMP expression associated with increased activity of the serine/threonine kinase Akt, and pharmacological inhibition of this enzyme resulted in a dramatic suppression of MMP expression in Ap3b1 deficient lung epithelial cells. Similarly, levels and activity of different MMPs were also found to be increased in the lungs of mice carrying the Bloc3 HPS gene mutation and in the bronchoalveolar lavage fluid of subjects with HPS. However, an association between MMP activity and disease severity was not detected in these individuals. CONCLUSIONS In summary, our findings indicate that MMP activity is dysregulated in the HPS lung, suggesting a role for these proteases as biological markers or pathogenic players in HPS lung disease.
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Affiliation(s)
- Ross Summer
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Rachana Krishna
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - DeLeila Schriner
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Karina Cuevas-Mora
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Dominic Sales
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Rachel Para
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Jesse Roman
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Carl Nieweld
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
| | - Bernadette R. Gochuico
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD USA
| | - Freddy Romero
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, USA
- Center for Translational Medicine and Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, 1020 Locust Street, JAH 354, Philadelphia, PA 19107 USA
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Gerondopoulos A, Langemeyer L, Liang JR, Linford A, Barr FA. BLOC-3 mutated in Hermansky-Pudlak syndrome is a Rab32/38 guanine nucleotide exchange factor. Curr Biol 2012; 22:2135-9. [PMID: 23084991 PMCID: PMC3502862 DOI: 10.1016/j.cub.2012.09.020] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/25/2012] [Accepted: 09/07/2012] [Indexed: 12/20/2022]
Abstract
Hermansky-Pudlak syndrome (HPS) is a human disease characterized by partial loss of pigmentation and impaired blood clotting [1–3]. These symptoms are caused by defects in the biogenesis of melanosomes and platelet dense granules, often referred to as lysosome-related organelles [2]. Genes mutated in HPS encode subunits of the biogenesis of lysosome-related organelles complexes (BLOCs). BLOC-1 and BLOC-2, together with the AP-3 clathrin adaptor complex, act at early endosomes to sort components required for melanin formation and melanosome biogenesis away from the degradative lysosomal pathway toward early stage melanosomes [4–6]. However the molecular functions of the Hps1-Hps4 complex BLOC-3 remain mysterious [7–9]. Like other trafficking pathways, melanosome biogenesis and transport of enzymes involved in pigmentation involves specific Rab GTPases, in this instance Rab32 and Rab38 [10–12]. We now demonstrate that BLOC-3 is a Rab32 and Rab38 guanine nucleotide exchange factor (GEF). Silencing of the BLOC-3 subunits Hps1 and Hps4 results in the mislocalization of Rab32 and Rab38 and reduction in pigmentation. In addition, we show that BLOC-3 can promote specific membrane recruitment of Rab32/38. BLOC-3 therefore defines a novel Rab GEF family with a specific function in the biogenesis of lysosome-related organelles.
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Affiliation(s)
- Andreas Gerondopoulos
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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Abstract
The advances that have been made over the last decade in microscopic, biochemical, molecular, and genetic techniques have led to substantial improvement in our understanding of platelet dense granule structure and function, and the implications of dense granule deficiencies for haemostasis. However, much has still to be learned. For example, what is the specific mechanism of docking and fusion that occurs during dense granule exocytosis? What are the roles of dense granule membrane proteins during exocytosis or after expression on the surface of activated platelets? Finally, how do the genetic defects identified in HPS and CHS result in the clinical phenotype of these diseases, and what does this tell us about the origin and function of the affected subcellular organelles?
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Affiliation(s)
- A McNicol
- Department of Oral Biology, University of Manitoba, Winnipeg, Canada
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