Cell and tissue research
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Cell and tissue research · Nov 2014
Expression of nucleobindin 1 (NUCB1) in pancreatic islets and other endocrine tissues.
The protein nucleobindin 1 (NUCB1; also known as CALNUC or Nuc) contains an intriguing combination of DNA- and calcium-binding motifs, a trait that it shares with the protein nucleobindin 2 (NUCB2; also known as nesfatin). NUCB2 has been implicated in several aspects of metabolic control and has been identified in a number of endocrine organs. No such comprehensive mapping of NUCB1 has been presented. ⋯ Where present, NUCB1 consistently appears to be associated with the Golgi apparatus. Thus, NUCB1 is broadly, but not ubiquitously, expressed in cells of the mouse endocrine system. Together with its location in the Golgi apparatus and its putative Ca(2+)-binding ability, this distribution suggests a role for NUCB1 in Ca(2+) handling/sensing in secretory cells.
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Optogenetics is the optical control of neuronal excitability by genetically delivered light-activated channels and pumps and represents a promising tool to fuel the study of circuit function in psychiatric animal models. This review highlights three developments. ⋯ We then discuss recent work in translating functional magnetic resonance imaging in small animals (in which optogenetics can be employed to reveal physiological mechanisms underlying disease-related alterations in brain circuits) to patients. Finally, we describe emerging technological developments for circuit manipulation in freely behaving animals.
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Cell and tissue research · Sep 2012
ReviewMammalian zona pellucida glycoproteins: structure and function during fertilization.
Zona pellucida (ZP) is a glycoproteinaceous translucent matrix that surrounds the mammalian oocyte and plays a critical role in the accomplishment of fertilization. In humans, it is composed of 4 glycoproteins designated as ZP1, ZP2, ZP3 and ZP4, whereas mouse ZP is composed of ZP1, ZP2 and ZP3 (Zp4 being a pseudogene). In addition to a variable sequence identity of a given zona protein among various species, human ZP1 and ZP4 are paralogs and mature polypeptide chains share an identity of 47%. ⋯ There are subtle differences in the downstream signaling events associated with ZP3 versus ZP1/ZP4-mediated induction of the acrosome reaction. For example, ZP3 but not ZP1/ZP4-mediated induction of the acrosome reaction is dependent on the activation of the Gi protein-coupled receptor. Thus, various studies suggest that, in contrast to mice, in humans more than one zona protein binds to spermatozoa and induces an acrosome reaction.
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Perineuronal nets (PNNs) are reticular structures that surround the cell body of many neurones, and extend along their dendrites. They are considered to be a specialized extracellular matrix in the central nervous system (CNS). PNN formation is first detected relatively late in development, as the mature synaptic circuitry of the CNS is established and stabilized. ⋯ PNN deposition around neurones helps to stabilize the established neuronal connections, and to restrict the plastic changes due to future experiences within the CNS. Disruption of PNNs can reactivate plasticity in many CNSs, allowing activity-dependent changes to once again modify neuronal connections. The mechanisms through which PNNs restrict CNS plasticity remain unclear, although recent advances promise to shed additional light on this important subject.
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Cell and tissue research · Jul 2012
ReviewTraumatology of the optic nerve and contribution of crystallins to axonal regeneration.
Within a few decades, the repair of long neuronal pathways such as spinal cord tracts, the optic nerve or intracerebral tracts has gone from being strongly contested to being recognized as a potential clinical challenge. Cut axonal stumps within the optic nerve were originally thought to retract and become irreversibly necrotic within the injury zone. Optic nerve astrocytes were assumed to form a gliotic scar and remodelling of the extracellular matrix to result in a forbidden environment for re-growth of axons. ⋯ These are the first data showing that axonal regeneration is related to crybb2 movement within neurons and to additional stimulation of CNTF. We demonstrate that neuronal crystallins constitute a novel class of neurite-promoting factors that probably operate through an autocrine and paracrine mechanism and that they can be used in neurodegenerative diseases. Thus, the post-injury fate of neurons cannot be seen merely as inevitable but, instead, must be regarded as a challenge to shape conditions for initiating growth cone formation to repair the damaged optic nerve.