Volume 30 Issue 12, December 2023

DNA polymerase θ (POLQ) repairs mitotic DNA breaks; this requires RHINO and PLK1, averts genomic instability and may underlie effects of POLQ inhibitors in HDR-deficient cancer cells. We discuss recent work on mitotic DNA break processing and repair, the need for multiple DSB repair pathways and implications of therapeutic POLQ targeting in cancer.

The mitochondrial translocase complex TIM23 targets several hundreds of proteins to their location in the mitochondrial matrix or inner membrane. Recent studies provide important structural and mechanistic insights into the actions of the protein-import machinery in mitochondria.

The androgen receptor forms nuclear condensates associated with gene transcription. Investigating the molecular basis of condensate formation led us to discover an approach for optimizing small molecules that inhibit the receptor in a currently untreatable form of prostate cancer.

An Ago2^HA/HA mouse model combined with super-resolution microscopy, molecular and biochemical assays allowed us to stringently characterize AGO2 regulation in vivo. We found that in quiescent splenocytes, AGO2 localizes almost exclusively to the nucleus, where it binds to the RNA of young mobile transposons and represses their expression through its catalytic domain.

We describe how transcription start site (TSS) choice of thousands of genes results in transcript isoforms with potential for distinct post-transcriptional regulation affecting translation and cell behavior. We show that dynamic switching between initiation sites defines cancer proliferation, differentiation and treatment response, indicating start site determination as a potential diagnostic tool.

The human ATPase p97 (also known as VCP) unfolds protein substrates by translocating them through its central channel. This process is highly regulated by numerous adapter proteins. Structures of p97 in complex with the unusual adapter UBXD1 reveal how this protein coordinates p97 hexamer remodeling and ring opening by expansive interactions across multiple p97 protomers.

In this Review, the authors discuss the various ways that alternative splicing sculpts the landscape of protein interactions with their partners, essentially all types of biomolecules, and the implications of alternative interactions at the molecular, cellular and disease level.

The authors reveal the architecture and functional annotation of large immunophilin-containing Hsp90–apo-GR complexes by systematic incorporation of photocrosslinker inside human cells and show that FKBP51 and FKBP52 differentially interact with the apo-GR.

Cryogenic electron microscopy structures reveal how the immunophilin co-chaperones, FKBP51 and FKBP52, each engage Hsp90–client complexes to directly stabilize a folded, ligand-bound client, the glucocorticoid receptor, and promote the next stage of client maturation.

The authors show that the lncRNA-derived microprotein SMIMP, which is shown to promote tumor formation, regulates cohesin core subunit binding to cis-regulatory elements and alters the expression of tumor-suppressive cell cycle regulators.

Using structural and functional analysis, Li et al. reveal the architecture of the Rpd3S histone deacetylase complex and mechanism of its chromatin targeting and deacetylation.

Glutaminase is a mitochondrial complex that deaminates glutamine to form glutamate. Here the authors investigate inorganic-phosphate-induced enzyme filamentation, revealing an allosteric mechanism and roles of filamentous glutaminase in mitochondrial morphology and recycling.

Here, the authors show how binding of talin and kindlin to the β-integrin cytoplasmic tail increases talin and decreases kindlin affinity toward it, providing insights into mechanisms of integrin activation.

Using cryo-EM, here the authors structurally delineate the Elongin–RNA polymerase II holocomplex. They show that Elongin allosterically regulates the transcribing RNA polymerase II via a latch that affects its conformational mobility.

Here, Kasaragod et al. solve structures of the GABA_A receptor α5 subunit in complex with different classes of positive and negative allosteric modulators to explain the binding modes and the molecular basis of selectivity.

Here the authors characterize the sequence-specific effect of an anticancer compound on mRNA cleavage, providing insights into the mechanism of mRNA 3′ processing.

Transcription factors are rich in intrinsic disorder and therefore hard to drug. The authors improve an experimental drug for castration-resistant prostate cancer by learning how the activation domain of the androgen receptor activates transcription.

Here, using CAGE-seq, the authors show that transcription start site choice in thousands of genes may endow transcripts with distinct post-transcriptional fates, with dynamic switching defining cancer cell proliferation, differentiation and treatment response.

Here the authors show that, in the absence of Pi3K–AKT–mTOR signaling, AGO2 accumulates in the nucleus of quiescent cells, where it binds to young retrotransposons and represses their expression.

Here the authors report structural and biochemical analyses of the mitochondrial TOM–TIM23 supercomplex, providing insights into how the substrates are transported through the outer and inner membranes.

Braxton et al. report structures of human p97/VCP bound to the UBXD1 adaptor involved in autophagy. The structures reveal how UBXD1 utilizes multiple interaction domains to remodel and open the hexamer ring, revealing its role in p97 regulation.