Human steroid 5α-reductase 2 (SRD5A2) is an integral membrane enzyme in steroid metabolism and catalyzes the reduction of testosterone to dihydrotestosterone. Mutations in the SRD5A2 gene have been linked to 5α-reductase deficiency and prostate cancer. Finasteride and dutasteride, as SRD5A2 inhibitors, are widely used antiandrogen drugs for benign prostate hyperplasia. The molecular mechanisms underlying enzyme catalysis and inhibition for SRD5A2 and other eukaryotic integral membrane steroid reductases remain elusive due to a lack of structural information. Here, we report a crystal structure of human SRD5A2 at 2.8 Å, revealing a unique 7-TM structural topology and an intermediate adduct of finasteride and NADPH as NADP-dihydrofinasteride in a largely enclosed binding cavity inside the transmembrane domain. Structural analysis together with computational and mutagenesis studies reveal the molecular mechanisms of the catalyzed reaction and of finasteride inhibition involving residues E57 and Y91. Molecular dynamics simulation results indicate high conformational dynamics of the cytosolic region that regulate NADPH/NADP+ exchange. Mapping disease-causing mutations of SRD5A2 to our structure suggests molecular mechanisms for their pathological effects. Our results offer critical structural insights into the function of integral membrane steroid reductases and may facilitate drug development.

The signaling of prostaglandin D (PGD) through G-protein-coupled receptor (GPCR) CRTH2 is a major pathway in type 2 inflammation. Compelling evidence suggests the therapeutic benefits of blocking CRTH2 signaling in many inflammatory disorders. Currently, a number of CRTH2 antagonists are under clinical investigation, and one compound, fevipiprant, has advanced to phase 3 clinical trials for asthma. Here, we present the crystal structures of human CRTH2 with two antagonists, fevipiprant and CAY10471. The structures, together with docking and ligand-binding data, reveal a semi-occluded pocket covered by a well-structured amino terminus and different binding modes of chemically diverse CRTH2 antagonists. Structural analysis suggests a ligand entry port and a binding process that is facilitated by opposite charge attraction for PGD, which differs significantly from the binding pose and binding environment of lysophospholipids and endocannabinoids, revealing a new mechanism for lipid recognition by GPCRs.

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Kidney ankyrin repeat-containing proteins (KANK1/2/3/4) belong to a family of scaffold proteins, playing critical roles in cytoskeleton organization, cell polarity, and migration. Mutations in KANK proteins are implicated in cancers and genetic diseases, such as nephrotic syndrome. KANK proteins can bind various target proteins through different protein regions, including a highly conserved ankyrin repeat domain (ANKRD). However, the molecular basis for target recognition by the ANKRD remains elusive. In this study, we solved a high-resolution crystal structure of the ANKRD of KANK1 in complex with a short sequence of the motor protein kinesin family member 21A (KIF21A), revealing that the highly specific target-binding mode of the ANKRD involves combinatorial use of two interfaces. Mutations in either interface disrupted the KANK1-KIF21A interaction. Cellular immunofluorescence localization analysis indicated that binding-deficient mutations block recruitment of KIF21A to focal adhesions by KANK1. In conclusion, our structural study provides mechanistic explanations for the ANKRD-mediated recognition of KIF21A and for many disease-related mutations identified in human KANK proteins.

Cells make use of molecular motors to transport small molecules, macromolecules and cellular organelles to target region to execute biological functions, which is utmost important for polarized cells, such as neurons. In particular, cytoskeleton motors play fundamental roles in neuron polarization, extension, shape and neurotransmission. Cytoskeleton motors comprise of myosin, kinesin and cytoplasmic dynein. F-actin filaments act as myosin track, while kinesin and cytoplasmic dynein move on microtubules. Cytoskeleton motors work together to build a highly polarized and regulated system in neuronal cells via different molecular mechanisms and functional regulations. This review discusses the structures and working mechanisms of the cytoskeleton motors in neurons.

Colorectal cancer (CRC) is a major contributor to cancer-associated morbidity worldwide and over one-third of CRC is located in the rectum. Neoadjuvant chemoradiotherapy (nCRT) followed by surgical resection is commonly applied to treat locally advanced rectal cancer (LARC). In this review, we summarize current and novel concepts of neoadjuvant therapy for LARC such as total neoadjuvant therapy and describe how these developments impact treatment response. Moreover, as response to nCRT is highly divergent in rectal cancers, we discuss the role of potential predictive biomarkers. We review recent advances in biomarker discovery, from a clinical as well as a histopathological and molecular perspective. Furthermore, the role of emerging predictive biomarkers derived from the tumor environment such as immune cell composition and gut microbiome is presented. Finally, we describe how different tumor models such as patient-derived cancer organoids are used to identify novel predictive biomarkers for chemoradiotherapy (CRT) in rectal cancer.

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Targeting cancer hallmarks is a cardinal strategy to improve antineoplastic treatment. However, cross-talk between signaling pathways and key oncogenic processes frequently convey resistance to targeted therapies. The p53 and Wnt pathway play vital roles for the biology of many tumors, as they are critically involved in cancer onset and progression. Over recent decades, a high level of interaction between the two pathways has been revealed. Here, we provide a comprehensive overview of molecular interactions between the p53 and Wnt pathway discovered in cancer, including complex feedback loops and reciprocal transactivation. The mutational landscape of genes associated with p53 and Wnt signaling is described, including mutual exclusive and co-occurring genetic alterations. Finally, we summarize the functional consequences of this cross-talk for cancer phenotypes, such as invasiveness, metastasis or drug resistance, and discuss potential strategies to pharmacologically target the p53-Wnt interaction.