Hog1/p38 and ZAKα drive Shwachman-Diamond syndrome and provide targets to improve cell growth
Shwachman-Diamond syndrome (SDS) is a ribosomopathy characterized by neutropenia, pancreatic insufficiency, skeletal defects, and predisposition to leukemia. Most cases result from biallelic SBDS mutations that impairing 80S ribosome and polysome assembly. In yeast lacking SDO1 (the SBDS ortholog), growth slows dramatically and the p38 ortholog Hog1 signaling is elevated by multiple types of stress. SBDS-deficient HeLa cells exhibited reduced proliferation and slowed cell cycling. The p38 kinase was constitutively activated in SBDS mutants and SDS patient-derived blood cells. Because ZAK detects ribosome dysfunction, its activation links ribosomal defects to stress kinase pathways in SDS. Suppressing p38 or its upstream activator ZAK restored cell growth and reduced stress signaling. These findings reveal an evolutionarily conserved-independent mechanism via p38 drives SDS pathophysiology and identifies stress kinases as potential therapeutic targets for ribosomal dysfunction.