{"id":"3edbeeab-29ca-5ec3-96d1-74e92648b776","stable_key":"5102beb6-9f61-500e-af10-9ac63649e0b7:renal-wnk4-spak-activation-opposes-acute-off","predicate":"sustains-during-acute-potassium-challenge","statement":"Chloride-insensitive WNK4 blocked high-K NCC dephosphorylation in HEK cells; the authors inferred that WNK4-SPAK inhibition is required for the rapid response.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"e8704440-123e-5bac-bd96-122c50ee5ddc","mechanism_event_label":"A strongly active kinase relay can keep NCC phosphorylated during an acute potassium challenge.","subject":{"id":"2623ebf1-717c-5bca-9034-75ad82fb7bed","slug":"wnk4-l319f-l321f","display_name":"WNK4 L319F/L321F chloride-insensitive variant","entity_type_key":"protein_state"},"object":{"id":"8197e69c-215b-5cd4-bf4b-edde6708ea8f","slug":"ncc-phosphorylation","display_name":"NCC phosphorylation","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"e8704440-123e-5bac-bd96-122c50ee5ddc","stable_key":"5102beb6-9f61-500e-af10-9ac63649e0b7:renal-wnk4-spak-activation-opposes-acute-off-event","event_type":"biochemical_relationship","label":"A strongly active kinase relay can keep NCC phosphorylated during an acute potassium challenge.","description":"Chloride-insensitive WNK4 blocked high-K NCC dephosphorylation in HEK cells; the authors inferred that WNK4-SPAK inhibition is required for the rapid response.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"60a8da52-44b6-5714-ae92-2776e6ed5aeb","slug":"wnk4","display_name":"WNK lysine deficient protein kinase 4","entity_type_key":"protein"},"role":"wild-type-reference","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"8197e69c-215b-5cd4-bf4b-edde6708ea8f","slug":"ncc-phosphorylation","display_name":"NCC phosphorylation","entity_type_key":"cellular_process"},"role":"measured-target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"2623ebf1-717c-5bca-9034-75ad82fb7bed","slug":"wnk4-l319f-l321f","display_name":"WNK4 L319F/L321F chloride-insensitive variant","entity_type_key":"protein_state"},"role":"causal-subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"6ac31e68-8970-5167-aca8-4ce8d90a66cc","slug":"stk39","display_name":"STE20/SPS1-related proline/alanine-rich kinase","entity_type_key":"protein"},"role":"relay","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"5dd31e52-f51e-51f3-880e-240abcc0ab1d","slug":"potassium-ion","display_name":"Potassium ion","entity_type_key":"ion"},"role":"challenge","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"63291643-1df9-5547-952a-9082838a350e","slug":"slc12a3","display_name":"Thiazide-sensitive sodium-chloride cotransporter","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"cross_nutrient","value_text":"Balance of kinase and phosphatase signaling controls Na/Cl transport responses to K.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_location","value_text":"Discussion; WNK4-LLFF HEK experiment and acute-versus-prolonged restriction comparison.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"HEK mutant expression with complementary mouse/kidney-slice experiments","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Inference about obligatory kinase shutdown is disputed; model and adaptation time matter.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Potassium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"potassium","display_name":"Potassium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens cell line; Mus musculus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A strongly active kinase relay can keep NCC phosphorylated during an acute potassium challenge.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[yang-2021-ncc-off-switch] Roles of WNK4 and SPAK in K+-mediated dephosphorylation of the NaCl cotransporter (2021). https://pmc.ncbi.nlm.nih.gov/articles/PMC8174808/ DOI: 10.1152/ajprenal.00459.2020","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"HEK cells and renal DCT","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"10d9be58-e0e5-5e1e-83d1-3985e4873802","evidence_kind":"source_excerpt","locator":"Lines 255-266","start_line":255,"end_line":266,"excerpt":"### renal-wnk4-spak-activation-opposes-acute-off\nChloride-insensitive WNK4 blocked high-K NCC dephosphorylation in HEK cells; the authors inferred that WNK4-SPAK inhibition is required for the rapid response.\nCondition category: machinery_impairment\nnutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A strongly active kinase relay can keep NCC phosphorylated during an acute potassium challenge.\norganism: Homo sapiens cell line; Mus musculus\ntissue_or_cell_type: HEK cells and renal DCT\nexperimental_model: HEK mutant expression with complementary mouse/kidney-slice experiments\nlimitations: Inference about obligatory kinase shutdown is disputed; model and adaptation time matter.\ncross_nutrient: Balance of kinase and phosphatase signaling controls Na/Cl transport responses to K.\nevidence_location: Discussion; WNK4-LLFF HEK experiment and acute-versus-prolonged restriction comparison.\n[yang-2021-ncc-off-switch] Roles of WNK4 and SPAK in K+-mediated dephosphorylation of the NaCl cotransporter (2021). https://pmc.ncbi.nlm.nih.gov/articles/PMC8174808/ DOI: 10.1152/ajprenal.00459.2020","model_system":"HEK mutant expression with complementary mouse/kidney-slice experiments","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [yang-2021-ncc-off-switch] Roles of WNK4 and SPAK in K+-mediated dephosphorylation of the NaCl cotransporter (2021). https://pmc.ncbi.nlm.nih.gov/articles/PMC8174808/ DOI: 10.1152/ajprenal.00459.2020","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"241226ee-6b7d-5cc7-9781-e6beb8ee1982","stable_key":"import-5102beb6-9f61-500e-af10-9ac63649e0b7","title":"Potassium: cross-nutrient mechanisms and deficiency (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"a8f89f8d84b48c0f93048dfc45f7f57a67dd9a7249968a096a14aeb03d8b7a52","revision_id":"de4ec6f4-58a1-537b-8169-97b783898df1","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[{"id":"b6bc8368-0e2a-5976-9b0b-407414876111","title":"Does acute potassium-induced NCC dephosphorylation require WNK-SPAK shutdown?","kind":"contradiction","status":"open","why":"The papers make opposing mechanistic interpretations: Yang et al. infer required kinase shutdown, whereas Penton et al. infer a chloride-independent route; Grimm et al. demonstrate direct PP1A action and adaptation-dependent suppression despite constitutive SPAK.","resolution":"Unresolved at a universal level. Chloride perturbations, mutant kinase strength, nephron specificity and prior dietary adaptation differ. Retain the opposing interpretations while avoiding a claim that the underlying measured results are identical experimental comparisons.","created_at":"2026-09-17 09:04:24","record_type":"conflict","display_label":"Recorded conflict","record_url":"/conflicts/b6bc8368-0e2a-5976-9b0b-407414876111","sides":[{"conflict_id":"b6bc8368-0e2a-5976-9b0b-407414876111","ordinal":0,"label":"Kinase shutdown required for the rapid response in the tested models","revision_id":"de4ec6f4-58a1-537b-8169-97b783898df1","start_line":255,"end_line":266,"quote":"### renal-wnk4-spak-activation-opposes-acute-off\nChloride-insensitive WNK4 blocked high-K NCC dephosphorylation in HEK cells; the authors inferred that WNK4-SPAK inhibition is required for the rapid response.\nCondition category: machinery_impairment\nnutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A strongly active kinase relay can keep NCC phosphorylated during an acute potassium challenge.\norganism: Homo sapiens cell line; Mus musculus\ntissue_or_cell_type: HEK cells and renal DCT\nexperimental_model: HEK mutant expression with complementary mouse/kidney-slice experiments\nlimitations: Inference about obligatory kinase shutdown is disputed; model and adaptation time matter.\ncross_nutrient: Balance of kinase and phosphatase signaling controls Na/Cl transport responses to K.\nevidence_location: Discussion; WNK4-LLFF HEK experiment and acute-versus-prolonged restriction comparison.\n[yang-2021-ncc-off-switch] Roles of WNK4 and SPAK in K+-mediated dephosphorylation of the NaCl cotransporter (2021). https://pmc.ncbi.nlm.nih.gov/articles/PMC8174808/ DOI: 10.1152/ajprenal.00459.2020","source_key":"import-5102beb6-9f61-500e-af10-9ac63649e0b7","source_title":"Potassium: cross-nutrient mechanisms and deficiency (2026-09-17)","claim_ids":["3edbeeab-29ca-5ec3-96d1-74e92648b776"]},{"conflict_id":"b6bc8368-0e2a-5976-9b0b-407414876111","ordinal":1,"label":"Native preparations retain high-K dephosphorylation during chloride perturbation","revision_id":"de4ec6f4-58a1-537b-8169-97b783898df1","start_line":229,"end_line":240,"quote":"### renal-native-high-k-cl-independent-ncc-off\nHigh-K-induced NCC dephosphorylation persisted during low extracellular chloride or chloride-channel blockade in mouse kidney preparations.\nCondition category: normal\nnutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The rapid high-potassium response can persist when tested chloride movements are disrupted.\norganism: Mus musculus\ntissue_or_cell_type: Native DCT\nexperimental_model: Perfused kidney and kidney slices\nlimitations: Pharmacological/ionic tests do not prove every chloride-sensitive step is absent.\ncross_nutrient: High K can suppress the sodium/chloride transporter through additional signaling.\nevidence_location: Primary abstract; low extracellular chloride and DIDS experiments.\n[penton-2016-native-potassium-switch] Extracellular K+ rapidly controls NaCl cotransporter phosphorylation in the native distal convoluted tubule by Cl--dependent and independent mechanisms (2016). https://pmc.ncbi.nlm.nih.gov/articles/PMC5088235/ DOI: 10.1113/JP272504","source_key":"import-5102beb6-9f61-500e-af10-9ac63649e0b7","source_title":"Potassium: cross-nutrient mechanisms and deficiency (2026-09-17)","claim_ids":["0aa15799-c947-5565-a7d6-0821d12f3b73"]},{"conflict_id":"b6bc8368-0e2a-5976-9b0b-407414876111","ordinal":2,"label":"Adapted phosphatase response can overcome constitutive SPAK","revision_id":"de4ec6f4-58a1-537b-8169-97b783898df1","start_line":281,"end_line":292,"quote":"### renal-k-adaptation-overcomes-active-spak\nAfter high-K dietary adaptation, DCT-specific constitutively active SPAK mice reduced NCC phosphorylation despite persistent kinase activation.\nCondition category: machinery_impairment\nnutrient_topic: Potassium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: With adaptation, the phosphate-removing response can overcome a continuously active kinase.\norganism: Mus musculus\ntissue_or_cell_type: DCT\nexperimental_model: Four-day dietary K loading in CA-SPAK mice\nlimitations: Response required higher plasma K than controls; not a general claim that kinase state is irrelevant.\ncross_nutrient: Dietary K adjusts the balance controlling Na/Cl transporter activation.\nevidence_location: Figure 1; Figures 4-5; Discussion.\n[grimm-2023-pp1a-ncc] Dietary potassium stimulates Ppp1Ca-Ppp1r1a dephosphorylation of kidney NaCl cotransporter and reduces blood pressure (2023). https://www.jci.org/articles/view/158498 DOI: 10.1172/JCI158498","source_key":"import-5102beb6-9f61-500e-af10-9ac63649e0b7","source_title":"Potassium: cross-nutrient mechanisms and deficiency (2026-09-17)","claim_ids":["3f43a000-1455-5088-a2a7-a971927c1d15"]}]}],"corrections":[],"research":null}