{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n HPS6 is a critical component of the biogenesis of lysosome‐related organelles complex‐2 (BLOC‐2), which mediates the intracellular trafficking of proteins to specialized organelles such as melanosomes, platelet dense granules, and Weibel–Palade bodies. As a subunit of BLOC‐2, HPS6 works in concert with HPS3 and HPS5 to ensure the proper delivery of key melanogenic enzymes—including tyrosinase and tyrosinase‐related protein 1—to maturing melanosomes; disruption of this trafficking leads to defective melanosome maturation and hypopigmentation in Hermansky–Pudlak syndrome (HPS) type 6 ["}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its role in melanosome biogenesis, HPS6 has been shown to interact directly with the dynactin p150^Glued subunit of the dynein–dynactin motor complex. By serving as a cargo adaptor for this retrograde transport machinery, HPS6 facilitates the movement of lysosomes from the cell periphery to the perinuclear region, thereby promoting proper lysosome maturation, acidification, and timely lysosomal protein degradation ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In endothelial cells, deficiency of HPS6 impairs the formation and proper tubulation of von Willebrand factor within Weibel–Palade bodies, a defect that contributes to compromised hemostatic function. Consistently, in platelets, mutations in HPS6 lead to deficient formation and release of dense granules, which underlie the bleeding tendencies observed in individuals with HPS type 6 ["}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "6", "end_ref": "9"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Moreover, studies in melanoma cells indicate that an intact HPS6 function is necessary for the formation of mature melanosomes. Loss-of-function mutations in HPS6 not only impair melanogenesis but may also increase the sensitivity of melanoma cells to chemotherapeutic agents, underscoring the multifaceted role of this protein in vesicular trafficking and organelle maturation ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "10"}]}, {"type": "t", "text": "].\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these findings illustrate that HPS6 is essential for the proper sorting and delivery of cargo proteins to lysosome-related organelles. Disruption of HPS6 function leads to a spectrum of cellular defects—including abnormal pigmentation and bleeding diatheses—which are characteristic of Hermansky–Pudlak syndrome type 6.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Santiago M Di Pietro, Juan M Falcón-Pérez, Esteban C Dell'Angelica "}, {"type": "b", "children": [{"type": "t", "text": "Characterization of BLOC-2, a complex containing the Hermansky-Pudlak syndrome proteins HPS3, HPS5 and HPS6."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Traffic (2004)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/j.1600-0854.2004.0171.x"}], "href": "https://doi.org/10.1111/j.1600-0854.2004.0171.x"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15030569"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15030569"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Rashi Gautam, Sreenivasulu Chintala, Wei Li, et al. 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