Structural basis of BAK activation in mitochondrial apoptosis initiation

BCL-2 proteins regulate mitochondrial poration in apoptosis initiation. How the pore-forming BCL-2 Effector BAK is activated remains incompletely understood mechanistically. Here we investigate autoactivation and direct activation by BH3-only proteins, which cooperate to lower BAK threshold in membrane poration and apoptosis initiation. We define in trans BAK autoactivation as the asymmetric “BH3-in-groove” triggering of dormant BAK by active BAK. BAK autoactivation is mechanistically similar to direct activation. The structure of autoactivated BAK BH3-BAK complex reveals the conformational changes leading to helix α1 destabilization, which is a hallmark of BAK activation. Helix α1 is destabilized and restabilized in structures of BAK engaged by rationally designed, high-affinity activating and inactivating BID-like BH3 ligands, respectively. Altogether our data support the long-standing hit-and-run mechanism of BAK activation by transient binding of BH3-only proteins, demonstrating that BH3-induced structural changes are more important in BAK activation than BH3 ligand affinity.

Photosensitized Nickel Catalysis Enabled Silyl Radical Mediated Direct Activation of Carbamoyl Chlorides to Access (Hetero)aryl Carbamides

The transformation of a readily available molecule to a medicinally relevant functionality is the heart of organic synthesis which literally unfolds new direction in the field of drug discovery and development. Accordingly, synthetic chemistry fraternity is constantly striving to introduce a range of avant-garde techniques to construct an incredibly important fundamental entity like “amide bonds” which connect the amino acids in proteins and exist as a prevalent structural motif in biomolecules. In this context, we want to introduce the concept of cross-electrophile coupling by merging the photoredox and transition metal catalysis to construct carbamides from superabundant (hetero)aryl chlorides or bromides along with commercially feasible carbamoyl chlorides. However, there is barely any report on direct activation of carbamoyl chloride so far. To circumvent the challenge, we employ the intrinsic affinity of silyl radical species towards halogen atom to harness the carbamoyl radical directly from carbamoyl chlorides which is seemingly the first of its kind. The success of this protocol relies on the prior formation of ‘aryl halides to Ni-catalyst’ oxidative addition intermediate that assists in generation of the vital carbamoyl radical. The breadth of application of this technique is significantly demonstrated by the synthesis of a plethora of (hetero)aryl carbamides with diverse functionalities. As stated earlier, we outline the direct utility of this protocol by the late-stage amidation of halide containing drug molecules and pharmacophores.

Recent Developments and Aspects of Industrial Fluoroalkylation

Fluoroalkylations have received increasing attention in the academic and industrial environment due to the particular properties of the active ingredients that are strongly influenced by fluoroalkyl substituents. The inherent difficulties of introducing a fluoroalkyl substituent into advanced intermediates has triggered the development of an enormous number of specialized reagents, which, however, are often not suitable for large scale applications. In contrast to this reagent based fluoroalkylation approach, the direct activation of industrially readily available fluoroalkyl halides could be more suitable for a large-scale process. In this way the dithionite initiated fluoroalkylation as well as newly developed catalytically activated fluoroalkylation protocols were considered for industrial large-scale applications.

A case of cranial autonomic dysfunctions predominant migraine: Migraine sans ache

Pain is the essential part of migraine headaches along with other features, whereas, cranial autonomic symptoms (CAS)/signs are a predominant and essential part of trigeminal autonomic cephalalgias. What if other features of migraine are present but the pain is absent? One such variation in migraine symptomatology is reported in this case, where the pain was not there but CAS/signs were predominant along with other features of migraine. The possible mechanism for such variation, in this case, maybe desensitization of afferent loop (comprised by nociceptors in extracranial and intracranial pain-sensitive structures supplied by the trigeminal nerve) and direct activation of the trigemino-cervical complex and brainstem structures causing dissociation of pain from the rest of the features of migraine. In this case, as the pain part gets completely dissociated from CAS/signs, hence this condition can be termed as “migraine sans ache.” The patient was started on anti-migraine treatment and she responded wonderfully

Coordination chemogenetics for activation of GPCR-type glutamate receptors in brain tissue

Direct activation of cell-surface receptors is highly desirable for elucidating the physiological roles of receptors. However, subtype-selective ligands are very limited because of the high homology among receptor subtypes. A potential approach for selective activation of a receptor subtype is chemogenetics, in which both point mutagenesis of the receptors and designed ligands are used. However, ligand-binding properties are affected in most current methods. Here, we developed a chemogenetic method for direct activation of metabotropic glutamate receptor 1 (mGlu1), which plays essential roles in cerebellar functions in the brain. Our screening identified a mGlu1 mutant, mGlu1(N264H), that was directly activated by palladium complexes. Notably, a palladium complex showing low cytotoxicity successfully activated mGlu1 in mGlu1(N264H) knock-in mice, revealing that activation of endogenous mGlu1 is sufficient to evoke the critical cellular mechanism of synaptic plasticity, a basis of motor learning in the cerebellum.

Sinus venous thrombosis as a complication of COVID-19-associated hypercoagulability

Sinus venous thrombosis (SVT) is an increasingly recognised complication of not only SARS-CoV-2 infections, but also of SARS-CoV-2 vaccinations. SVT is attributed to hypercoagulability, a common complication of COVID-19, disregarding the severity of the infection. Hypercoagulability in COVID-19 is explained by direct activation of platelets, enhancing coagulation, by direct infection and indirect activation of endothelial cells by SARS-CoV-2, shifting endothelial cells from an anti-thrombotic to a pro-thrombotic state, by direct activation of complement pathways, promoting thrombin generation, or by immune thrombocytopenia, which also generates a thrombogenic state. Since SVT may occur even in anticoagulated COVID-19 patients and may have an unfavourable outcome, all efforts must be made to prevent this complication or to treat it accurately.

Forkhead transcription factor FKH-8 is a master regulator of primary cilia in C. elegans

SUMMARYCilia, either motile or non-motile (a.k.a primary or sensory), are complex evolutionary conserved eukaryotic structures composed of hundreds of proteins required for their assembly, structure and function that are collectively known as the ciliome. Ciliome mutations underlie a group of pleiotropic genetic diseases known as ciliopathies. Proper cilium function requires the tight coregulation of ciliome gene transcription, which is only fragmentarily understood. RFX transcription factors (TF) have an evolutionarily conserved role in the direct activation of ciliome genes both in motile and non-motile cilia cell types. In vertebrates, FoxJ1 and FoxN4 Forkhead (FKH) TFs work with RFX in the direct activation of ciliome genes, exclusively in motile cilia cell-types. No additional TFs have been described to act together with RFX in primary cilia cell-types in any organism. Here we describe FKH-8, a FKH TF, as master regulator of the primary ciliome in Caenorhabditis elegans. fkh-8 is expressed in all ciliated neurons in C. elegans, binds the regulatory regions of ciliome genes, regulates ciliome gene expression, cilium morphology and a wide range of behaviours mediated by sensory cilia. Importantly, we find FKH-8 function can be replaced by mouse FOXJ1 and FOXN4 but not by members of other mouse FKH subfamilies. In conclusion, our results show that RFX and FKH TF families act as master regulators of ciliogenesis also in sensory ciliated cell types and suggest that this regulatory logic could be an ancient trait predating functional cilia sub-specialization.