Reviews & Analysis

Chemotaxis enables immune cells to reach sites of infection, wounds to heal and the formation of embryonic patterns. Recent results have shed light on how cells orientate in chemotactic gradients, the forces that enable pseudopodia projection and the role of the endocytic cycle in movement.

Sterols and sterol derivatives modulate the Hedgehog (Hh) pathway at multiple levels. Progress in understanding Hh signalling will depend on deepening our knowledge of the cell biology of sterol metabolism and trafficking.

Although fusion proteins that function in different membrane-fusion events can be structurally diverse, their functional activities are often similar. Fusion proteins bring the two membranes into sufficiently close proximity and inject energy into the fusion process.

How do septins, GTP-binding proteins, function in a wide range of cellular processes, such as cell division, cytoskeletal organization and membrane remodelling? Electron microscopy and crystallographic studies provide a glimpse into septin-complex assembly that could answer this question.

The small nuclear GTPase Ran controls the directionality of macromolecular transport between the nucleus and the cytoplasm. Ran also has important roles during mitosis and directs nuclear-envelope dynamics, assembly of the mitotic spindle and the timing of cell-cycle transitions.

Filopodia are thin, actin-rich, finger-like structures that are involved in numerous cellular processes, such as cell migration, wound healing, neurite outgrowth and embryonic development. But what are the mechanisms that regulate filopodia formation in distinct cell types?

Asymmetric cell division, which occurs when a mother cell gives rise to two daughter cells with different fates, is crucial for generating diversity during development and for the function of stem cells. Studies in flies and worms have provided important advances for understanding this process.

DNA helicases and translocases have essential roles in nucleic acid metabolism. Processive helicases must translocate along DNA; however, enzyme self assembly and/or interactions with accessory proteins can regulate the separate translocase and helicase activities of some of these enzymes.

Adipose tissue controls whole-body lipid flux, thereby modulating both glucose and lipid homeostasis in humans. Discovery of new targets that regulate fatty acids in adipocytes might lead to therapeutic modalities that can prevent insulin resistance and type 2 diabetes.

Cell death has historically been divided into regulated (apoptotic) and unregulated (necrotic) mechanisms. Emerging evidence, however, suggests that these two categories do not adequately explain all cell death mechanisms. How and why might non-apoptotic, regulated cell death mechanisms have evolved?

Membrane nanotubes are thin extensions of the plasma membrane that connect cells transiently and might facilitate intercellular communication. Recent studies have revealed considerable heterogeneity in their structure, formation, mode of cargo transport and functional properties, depending on the cell types involved.

How do cytoskeletal components interact to control cellular processes? At the growing microtubule plus ends, microtubule plus-end tracking proteins (+TIPs) regulate different aspects of cell architecture by controlling microtubule dynamics, microtubule interactions with cellular structures and signalling factors, and forces exerted on microtubule networks.

Deadenylases shorten mRNA poly(A) tails and thereby regulate mRNA translation and decay. Recent studies have shown that these factors form different complexes. The recruitment of multifunctional deadenylase complexes to target mRNAs provides a unique node to control mRNA translation and decay.

Recent studies have provided insights into the mechanisms of voltage sensing and have identified new voltage-dependent proteins. Characterizing the general features of voltage sensors might lead to the discovery of further membrane proteins that are regulated by voltage.

Thetrans-Golgi network (TGN) is a major sorting centre for lipids and proteins that lies at the crossroads of endocytic and exocytic pathways. Recent studies have started to elucidate the molecular machineries that function in sorting and trafficking at the TGN.

Cells that undergo apoptosis are demolished in a controlled manner that minimizes damage to neighbouring cells and avoids the release of immunostimulatory molecules. These events are orchestrated primarily by a family of cysteine proteases called caspases, which target hundreds of proteins for restricted proteolysis.

Our understanding of the biological functions of small non-coding RNAs has been fostered by the analysis of genetic deletions of individual microRNAs (miRNAs) in mammals. These studies show that miRNAs are key regulators of animal development and are potential human disease loci.

The idea that processes can be self-organized and self-reproducing is more than 100 years old. But self-organization principles that were first developed in chemistry and physics are only now beginning to be applied to cellular and subcellular morphogenesis.

The Rpd3/Hda1 family of protein lysine deacetylases has numerous substrates and diverse functions. Whereas class I enzymes are multiprotein histone deacetylase complexes that are crucial for chromatin modification and transcriptional regulation, some class II enzymes function as signal transducers that are regulated by nucleocytoplasmic translocation.

Ribosomes have been the focus of structural and biochemical studies for more than 50 years. Recently, high-resolution structures have provided molecular snapshots of different intermediates in ribosome-mediated translation in atomic detail, which has revolutionized our understanding of the mechanism of protein synthesis.