Stk36, also known as Fused, is a serine-threonine protein kinase. It is essential for the assembly and function of motile cilia, and is involved in pathways such as ciliogenesis and the Hedgehog (Hh) signaling pathway. Defects in Stk36 can lead to various health problems, highlighting its biological importance. Genetic models, especially gene knockout models, have been crucial for studying its functions [1,3,4,5,6,7].

Gene knockout (KO) studies in mice and other organisms have provided significant insights. In Leishmania mexicana, Stk36 KO mutants showed flagellum cytoskeleton structural defects, indicating its role in flagellum assembly [1]. In mouse models, Stk36tmE4-/-mutants developed progressive hydrocephalus postnatally due to defective ciliogenesis and disturbed ciliary motility, with multiple motile cilia defects, and also disturbed the expression of ciliogenesis-related genes [4]. In an Australian Shepherd dog with a splice site variant in Stk36, it led to primary ciliary dyskinesia (PCD) with a central pair defect [2]. In humans, homozygous loss-of-function mutations in STK36 caused PCD with cilia orientation defects in respiratory epithelial cells [7].

In conclusion, Stk36 is crucial for ciliogenesis and the proper function of motile cilia. Model-based research, especially KO mouse models, has revealed its significance in conditions like hydrocephalus and PCD, enhancing our understanding of the biological processes underlying these diseases.