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PROteolysis-TArgeting Chimeras (PROTACs) are hetero-bifunctional molecules that recruit an E3 ubiquitin ligase to a given substrate protein resulting in its targeted degradation. Many potent PROTACs with specificity for dissimilar targets have been developed; however, the factors governing degradation selectivity within closely-related protein families remain elusive. Here, we generate isoform-selective PROTACs for the p38 MAPK family using a single warhead (foretinib) and recruited E3 ligase (von Hippel-Lindau). Based on their distinct linker attachments and lengths, these two PROTACs differentially recruit VHL, resulting in degradation of p38α or p38δ. We characterize the role of ternary complex formation in driving selectivity, showing that it is necessary, but insufficient, for PROTAC-induced substrate ubiquitination. Lastly, we explore the p38δ:PROTAC:VHL complex to explain the different selectivity profiles of these PROTACs. Our work attributes the selective degradation of two closely-related proteins using the same warhead and E3 ligase to heretofore underappreciated aspects of the ternary complex model. PROTACs enable targeted protein degradation by recruiting an E3 ligase to a specific substrate but the determinants of selectivity are not fully understood. Here, the authors show that varying the linker between warhead and E3 ligand and the orientation of the E3 ligase allow tuning PROTAC selectivity toward different p38 isoforms.

The mammalian SWItch/Sucrose Non-Fermentable (SWI/SNF) helicase SMARCA4 is frequently mutated in cancer and inactivation results in a cellular dependence on its paralog, SMARCA2, thus making SMARCA2 an attractive synthetic lethal target. However, published data indicates that achieving a high degree of selective SMARCA2 inhibition is likely essential to afford an acceptable therapeutic index, and realizing this objective is challenging due to the homology with the SMARCA4 paralog. Herein we report the discovery of a potent and selective SMARCA2 proteolysis-targeting chimera molecule (PROTAC), A947. Selective SMARCA2 degradation is achieved in the absence of selective SMARCA2/4 PROTAC binding and translates to potent in vitro growth inhibition and in vivo efficacy in SMARCA4 mutant models, compared to wild type models. Global ubiquitin mapping and proteome profiling reveal no unexpected off-target degradation related to A947 treatment. Our study thus highlights the ability to transform a non-selective SMARCA2/4-binding ligand into a selective and efficacious in vivo SMARCA2-targeting PROTAC, and thereby provides a potential new therapeutic opportunity for patients whose tumors contain SMARCA4 mutations. SMARCA2 has been identified as a synthetic lethal target in SMARCA4 mutated tumors, however, homology between the two has hindered the development of selective SMARCA2 inhibitors. Here, the authors synthesize a proteolysis targeting chimera (PROTAC) capable of SMARCA2 specific degradation and demonstrate its utility in the treatment of SMARCA4 mutated tumors.

Mammalian sterile 20-like kinase 1 (Mst1) is a MAPK kinase kinase kinase which is involved in a wide range of cellular responses, including apoptosis, lymphocyte adhesion and trafficking. The contribution of Mst1 to Ag-specific immune responses and autoimmunity has not been well defined. In this study, we provide evidence for the essential role of Mst1 in T cell differentiation and autoimmunity, using both genetic and pharmacologic approaches. Absence of Mst1 in mice reduced T cell proliferation and IL-2 production in vitro, blocked cell cycle progression, and elevated activation-induced cell death in Th1 cells. Mst1 deficiency led to a CD4+ T cell development path that was biased toward Th2 and immunoregulatory cytokine production with suppressed Th1 responses. In addition, Mst1-/- B cells showed decreased stimulation to B cell mitogens in vitro and deficient Ag-specific Ig production in vivo. Consistent with altered lymphocyte function, deletion of Mst1 reduced the severity of experimental autoimmune encephalomyelitis (EAE) and protected against collagen-induced arthritis development. Mst1-/- CD4+ T cells displayed an intrinsic defect in their ability to respond to encephalitogenic antigens and deletion of Mst1 in the CD4+ T cell compartment was sufficient to alleviate CNS inflammation during EAE. These findings have prompted the discovery of novel compounds that are potent inhibitors of Mst1 and exhibit desirable pharmacokinetic properties. In conclusion, this report implicates Mst1 as a critical regulator of adaptive immune responses, Th1/Th2-dependent cytokine production, and as a potential therapeutic target for immune disorders.

Mammalian sterile 20-like kinase 1 (Mst1) is a MAPK kinase kinase kinase which is involved in a wide range of cellular responses, including apoptosis, lymphocyte adhesion and trafficking. The contribution of Mst1 to Ag-specific immune responses and autoimmunity has not been well defined. In this study, we provide evidence for the essential role of Mst1 in T cell differentiation and autoimmunity, using both genetic and pharmacologic approaches. Absence of Mst1 in mice reduced T cell proliferation and IL-2 production in vitro, blocked cell cycle progression, and elevated activation-induced cell death in Th1 cells. Mst1 deficiency led to a CD4+ T cell development path that was biased toward Th2 and immunoregulatory cytokine production with suppressed Th1 responses. In addition, Mst1-/- B cells showed decreased stimulation to B cell mitogens in vitro and deficient Ag-specific Ig production in vivo. Consistent with altered lymphocyte function, deletion of Mst1 reduced the severity of experimental autoimmune encephalomyelitis (EAE) and protected against collagen-induced arthritis development. Mst1-/- CD4+ T cells displayed an intrinsic defect in their ability to respond to encephalitogenic antigens and deletion of Mst1 in the CD4+ T cell compartment was sufficient to alleviate CNS inflammation during EAE. These findings have prompted the discovery of novel compounds that are potent inhibitors of Mst1 and exhibit desirable pharmacokinetic properties. In conclusion, this report implicates Mst1 as a critical regulator of adaptive immune responses, Th1/Th2-dependent cytokine production, and as a potential therapeutic target for immune disorders.

Background Disease surveillance of diabetes among youth has relied mainly upon manual chart review. However, increasingly available structured electronic health record (EHR) data have been shown to yield accurate determinations of diabetes status and type. Validated algorithms to determine date of diabetes diagnosis are lacking. The objective of this work is to validate two EHR-based algorithms to determine date of diagnosis of diabetes. Methods A rule-based ICD-10 algorithm identified youth with diabetes from structured EHR data over the period of 2009 through 2017 within three children’s hospitals that participate in the SEARCH for Diabetes in Youth Study: Cincinnati Children’s Hospital, Cincinnati, OH, Seattle Children’s Hospital, Seattle, WA, and Children’s Hospital Colorado, Denver, CO. Previous research and a multidisciplinary team informed the creation of two algorithms based upon structured EHR data to determine date of diagnosis among diabetes cases. An ICD-code algorithm was defined by the year of occurrence of a second ICD-9 or ICD-10 diabetes code. A multiple-criteria algorithm consisted of the year of first occurrence of any of the following: diabetes-related ICD code, elevated glucose, elevated HbA1c, or diabetes medication. We assessed algorithm performance by percent agreement with a gold standard date of diagnosis determined by chart review. Results Among 3777 cases, both algorithms demonstrated high agreement with true diagnosis year and differed in classification ( p  = 0.006): 86.5% agreement for the ICD code algorithm and 85.9% agreement for the multiple-criteria algorithm. Agreement was high for both type 1 and type 2 cases for the ICD code algorithm. Performance improved over time. Conclusions Year of occurrence of the second ICD diabetes-related code in the EHR yields an accurate diagnosis date within these pediatric hospital systems. This may lead to increased efficiency and sustainability of surveillance methods for incidence of diabetes among youth.

Disease surveillance of diabetes among youth has relied mainly upon manual chart review. However, increasingly available structured electronic health record (EHR) data have been shown to yield accurate determinations of diabetes status and type. Validated algorithms to determine date of diabetes diagnosis are lacking. The objective of this work is to validate two EHR-based algorithms to determine date of diagnosis of diabetes. A rule-based ICD-10 algorithm identified youth with diabetes from structured EHR data over the period of 2009 through 2017 within three children's hospitals that participate in the SEARCH for Diabetes in Youth Study: Cincinnati Children's Hospital, Cincinnati, OH, Seattle Children's Hospital, Seattle, WA, and Children's Hospital Colorado, Denver, CO. Previous research and a multidisciplinary team informed the creation of two algorithms based upon structured EHR data to determine date of diagnosis among diabetes cases. An ICD-code algorithm was defined by the year of occurrence of a second ICD-9 or ICD-10 diabetes code. A multiple-criteria algorithm consisted of the year of first occurrence of any of the following: diabetes-related ICD code, elevated glucose, elevated HbA1c, or diabetes medication. We assessed algorithm performance by percent agreement with a gold standard date of diagnosis determined by chart review. Among 3777 cases, both algorithms demonstrated high agreement with true diagnosis year and differed in classification (p = 0.006): 86.5% agreement for the ICD code algorithm and 85.9% agreement for the multiple-criteria algorithm. Agreement was high for both type 1 and type 2 cases for the ICD code algorithm. Performance improved over time. Year of occurrence of the second ICD diabetes-related code in the EHR yields an accurate diagnosis date within these pediatric hospital systems. This may lead to increased efficiency and sustainability of surveillance methods for incidence of diabetes among youth.

Adaptor protein 2-associated kinase 1 (AAK1) is a member of the Ark1/Prk1 family of serine/threonine kinases and plays a role in modulating receptor endocytosis. AAK1 was identified as a potential therapeutic target for the treatment of neuropathic pain when it was shown that AAK1 knock out (KO) mice had a normal response to the acute pain phase of the mouse formalin model, but a reduced response to the persistent pain phase. Herein we report our early work investigating a series of pyrrolo[2,1- f ][1,2,4]triazines as part of our efforts to recapitulate this KO phenotype with a potent, small molecule inhibitor of AAK1. The synthesis, structure–activity relationships (SAR), and in vivo evaluation of these AAK1 inhibitors is described. Graphical Abstract

Adaptor protein 2-associated kinase 1 (AAK1) is a member of the Ark1/Prk1 family of serine/threonine kinases and plays a role in modulating receptor endocytosis. AAK1 was identified as a potential therapeutic target for the treatment of neuropathic pain when it was shown that AAK1 knock out (KO) mice had a normal response to the acute pain phase of the mouse formalin model, but a reduced response to the persistent pain phase. Herein we report our early work investigating a series of pyrrolo[2,1-f][1,2,4]triazines as part of our efforts to recapitulate this KO phenotype with a potent, small molecule inhibitor of AAK1. The synthesis, structure-activity relationships (SAR), and in vivo evaluation of these AAK1 inhibitors is described.Adaptor protein 2-associated kinase 1 (AAK1) is a member of the Ark1/Prk1 family of serine/threonine kinases and plays a role in modulating receptor endocytosis. AAK1 was identified as a potential therapeutic target for the treatment of neuropathic pain when it was shown that AAK1 knock out (KO) mice had a normal response to the acute pain phase of the mouse formalin model, but a reduced response to the persistent pain phase. Herein we report our early work investigating a series of pyrrolo[2,1-f][1,2,4]triazines as part of our efforts to recapitulate this KO phenotype with a potent, small molecule inhibitor of AAK1. The synthesis, structure-activity relationships (SAR), and in vivo evaluation of these AAK1 inhibitors is described.