Kinome siRNA Screen Identifies Regulators of Ciliogenesis and Hedgehog Signal Transduction

Abstract

Disruption or improper activation of the Hedgehog (Hh) pathway is associated with developmental abnormalities and cancer. Although characterized in Drosophila, the mechanisms that mediate the Hh signal downstream of the Smoothened (Smo) seven-transmembrane protein in vertebrates remain poorly understood. In particular, the Fused (Fu) kinase, which mediates Hh signaling in flies, is dispensable in mammals. To identify kinases that positively regulate the Hh pathway in mammals, we screened a mouse kinome small interfering RNA library and validated nine candidates that modulate Hh signaling. Among these candidates, Nek1 and Prkra did not directly function in the Hh pathway but exerted their effects on Hh signaling indirectly through a primary role in ciliogenesis. In contrast, another kinase, Cdc2l1, directly participated in the Hh pathway. Cdc2l1 was necessary and sufficient for activation of the Hh pathway, functioning downstream of Smo and upstream of the Glioma-associated (Gli) transcription factors. More specifically, Cdc2l1 interacted with the negative regulator Suppressor of Fused (Sufu) and relieved its inhibition on Gli, thus providing a mechanism for how Cdc2l1 might play a role in Hh signaling. Finally, with zebrafish as model organism, we showed that Cdc2l1 activated the Hh pathway in vivo. We propose that Cdc2l1 is a previously unrecognized member of the Hh signal transduction cascade.

Systematic Kinome shRNA Screening Identifies CDK11 (PITSLRE) Kinase Expression Is Critical for Osteosarcoma Cell Growth and Proliferation

“…Among the targeted kinase genes, we found that knocking down the expression of CDK11, PLK1, DYRK1B, and ROCK1 led to inhibitory growth effects. Of those kinases that we found critical to osteosarcoma cell growth, the elevated expression of PLK1, DYRK1B, and ROCK1 have been previously reported in various human tumors (6,12,(18)(19)(20)(21)(22)(23)(24). However, direct evidence regarding the relationship between expression of CDK11 and cancer cell growth and survival is lacking.…”

“…By kinome-wide siRNA screen for Hedgehog (Hh) regulators, CDK11 has been shown to directly participate in the Hh pathway. CDK11 is necessary and sufficient for the activation of the Hh pathway, functioning downstream of Smo and upstream of the glioma-associated (Gli) transcription factors (19). CDK11 is also a modulator of autophagy in human cells (30).…”

Dual Function of UNC-51-like Kinase 3 (Ulk3) in the Sonic Hedgehog Signaling Pathway

“…Hitherto, apart from Gli proteins, three mammalian proteins, SAP18, Galectin3, and Cdc2l1, have been identified as proteins able to physically interact with Sufu (55)(56)(57). Besides, Sufu has been shown to move to primary cilia in response to Shh signaling (58).…”

Activation of the hedgehog-signaling pathway in human cancer and the clinical implications

“…Gli molecules are now processed to active forms (GliA), which will activate the Hh target genes. (Evangelista et al, 2008;Varjosalo et al, 2008), but their exact functions in Hh signaling remain to be established.…”