Duplication of a chromosome 2 segment in production CHO cell lines correlates with age-related growth improvement.

Monitoring the stability of recombinant Chinese Hamster Ovary (CHO) cell lines is essential to ensure the selection of production cell lines suitable for biomanufacturing. It has been frequently observed that recombinant CHO cell lines develop phenotypic changes upon aging, such as accelerated cell growth in late generation cultures. However, the mechanism responsible for age-correlated changes is poorly understood.

Design and Characterization of Prodrug-like Inhibitors for Preventing Glutamate Efflux through Reverse Transport.

Glutamate transporters are responsible for active transport of the major excitatory neurotransmitter glutamate across the cell membrane, regulating the extracellular glutamate concentration in the mammalian brain. Extracellular glutamate levels in the brain are usually in the submicromolar range but can increase by exocytosis, inhibition of cellular uptake, or through glutamate release by reverse transport, as well as other mechanisms, which can lead to neurodegeneration and neuronal cell death. Such conditions can be encountered upon energy deprivation during an ischemic stroke.

Alanine serine cysteine transporter (ASCT) substrate binding site properties probed with hydroxyhomoserine esters.

The glutamine transporter ASCT2 is highly overexpressed in cancer cells. Block of glutamine uptake by ASCT2 is a potential strategy to inhibit growth of cancer cells. However, pharmacology of the ASCT2 binding site is not well established.

Rational design of ASCT2 inhibitors using an integrated experimental-computational approach.

ASCT2 (SLC1A5) is a sodium-dependent neutral amino acid transporter that controls amino acid homeostasis in peripheral tissues. In cancer, ASCT2 is up-regulated where it modulates intracellular glutamine levels, fueling cell proliferation. Nutrient deprivation via ASCT2 inhibition provides a potential strategy for cancer therapy.

Pre-Steady-State Kinetics and Reverse Transport in Rat Glutamate Transporter EAAC1 with an Immobilized Transport Domain.

Plasma membrane glutamate transporters move glutamate across the cell membrane in a process that is thought to involve elevator-like movement of the transport domain relative to the static trimerization domain. Conformational changes associated with this elevator-like movement have been blocked by covalent crosslinking of cysteine pairs inserted strategically in several positions in the transporter structure, resulting in inhibition of steady-state transport activity. However, it is not known how these crosslinking restraints affect other partial reactions of the transporter that were identified based on pre-steady-state kinetic analysis.

Interaction of the neutral amino acid transporter ASCT2 with basic amino acids.

Glutamine transport across cell membranes is performed by a variety of transporters, including the alanine serine cysteine transporter 2 (ASCT2). The substrate-binding site of ASCT2 was proposed to be specific for small amino acids with neutral side chains, excluding basic substrates such as lysine. A series of competitive inhibitors of ASCT2 with low µM affinity were developed previously, on the basis of the 2,4-diaminobutyric acid (DAB) scaffold with a potential positive charge in the side chain.

Genetically Encoded Halide Sensor-Based Fluorescent Assay for Rapid Screening of Glutamate Transport and Inhibition.

Glutamate is the main excitatory neurotransmitter in the mammalian central nervous system. Excitatory amino acid transporters (EAATs) are a family of transmembrane transporters responsible for glutamate uptake into cells, and their malfunction is related to a variety of diseases, including neurodegenerative diseases and stroke. Screening for and developing inhibitors of EAATs as well as related transporters is a significant field of study for biomedical and pharmaceutical applications.

A K/Na co-binding state: Simultaneous competitive binding of K and Na to glutamate transporters.

Plasma membrane-associated glutamate transporters play a key role in signaling by the major excitatory neurotransmitter glutamate. Uphill glutamate uptake into cells is energetically driven by coupling to co-transport of three Na ions. In exchange, one K ion is counter-transported.

Transient Kinetics Reveal Mechanism and Voltage Dependence of Inhibitor and Substrate Binding to Glutamate Transporters.

Plasma-membrane glutamate transporters of the excitatory amino acid transporter (EAAT) family are important for maintaining a low glutamate concentration in the extracellular space of the mammalian brain. Glutamate is believed to be transported in its negatively charged form and energetically driven by the cotransport of three sodium ions, at least two of which are bound within the dielectric of the membrane. It was hypothesized that binding of substrates and competitive inhibitors is also electrogenic because the binding site is located near the center of the membrane.