Kinase activity of casein kinase 1 delta (CK1δ) is modulated by protein kinase C α (PKCα) by site-specific phosphorylation within the kinase domain of CK1δ

Casein Kinase 1α-A Target for Prostate Cancer Therapy?

The androgen receptor (AR) is a key driver of prostate cancer (PCa) and, as such, current mainstay treatments target this molecule. However, resistance commonly arises to these therapies and, therefore, additional targets must be evaluated to improve patient outcomes. Consequently, alternative approaches for indirectly targeting the AR are sought. AR crosstalk with other signalling pathways, including several protein kinase signalling cascades, has been identified as a potential route to combat therapy resistance. The casein kinase 1 (CK1) family of protein kinases phosphorylate a multitude of substrates, allowing them to regulate a diverse range of pathways from the cell cycle to DNA damage repair. As well as its role in several signalling pathways that are de-regulated in PCa, mutational data suggest its potential to promote prostate carcinogenesis. CK1α is one isoform predicted to regulate AR activity via phosphorylation and has been implicated in the progression of several other cancer types. In this review, we explore how the normal biological function of CK1 is de-regulated in cancer, the impact on signalling pathways and how this contributes towards prostate tumourigenesis, with a particular focus on the CK1α isoform as a novel therapeutic target for PCa.

Comprehensive Characterization of CK1δ-Mediated Tau Phosphorylation in Alzheimer’s Disease

A main pathological event in Alzheimer’s disease is the generation of neurofibrillary tangles originating from hyperphosphorylated and subsequently aggregated tau proteins. Previous reports demonstrated the critical involvement of members of the protein kinase family CK1 in the pathogenesis of Alzheimer’s disease by hyperphosphorylation of tau. However, precise mechanisms and effects of CK1-mediated tau phosphorylation are still not fully understood. In this study, we analyzed recombinant tau441 phosphorylated by CK1δ in vitro via mass spectrometry and identified ten potential phosphorylation sites, five of them are associated to Alzheimer’s disease. To confirm these results, in vitro kinase assays and two-dimensional phosphopeptide analyses were performed with tau441 phosphomutants confirming Alzheimer’s disease-associated residues Ser68/Thr71 and Ser289 as CK1δ-specific phosphorylation sites. Treatment of differentiated human neural progenitor cells with PF-670462 and Western blot analysis identified Ser214 as CK1δ-targeted phosphorylation site. The use of an in vitro tau aggregation assay demonstrated a possible role of CK1δ in tau aggregation. Results obtained in this study highlight the potential of CK1δ to be a promising target in the treatment of Alzheimer’s disease.

Dangerous Duplicity: The Dual Functions of Casein Kinase 1 in Parasite Biology and Host Subversion

Casein Kinase 1 (CK1) family members are serine/threonine protein kinases that are involved in many biological processes and highly conserved in eukaryotes from protozoan to humans. Even though pathogens exploit host CK1 signaling pathways to survive, the role of CK1 in infectious diseases and host/pathogen interaction is less well characterized compared to other diseases, such as cancer or neurodegenerative diseases. Here we present the current knowledge on CK1 in protozoan parasites highlighting their essential role for parasite survival and their importance for host-pathogen interactions. We also discuss how the dual requirement of CK1 family members for parasite biological processes and host subversion could be exploited to identify novel antimicrobial interventions.

Structure, regulation, and (patho-)physiological functions of the stress-induced protein kinase CK1 delta (CSNK1D)

Members of the highly conserved pleiotropic CK1 family of serine/threonine-specific kinases are tightly regulated in the cell and play crucial regulatory roles in multiple cellular processes from protozoa to human. Since their dysregulation as well as mutations within their coding regions contribute to the development of various different pathologies, including cancer and neurodegenerative diseases, they have become interesting new drug targets within the last decade. However, to develop optimized CK1 isoform-specific therapeutics in personalized therapy concepts, a detailed knowledge of the regulation and functions of the different CK1 isoforms, their various splice variants and orthologs is mandatory. In this review we will focus on the stress-induced CK1 isoform delta (CK1δ), thereby addressing its regulation, physiological functions, the consequences of its deregulation for the development and progression of diseases, and its potential as therapeutic drug target.