Proteomics Reveals Distinctive Host Cell Protein Expression Patterns in Fed-Batch and Perfusion Cell Culture Processes.

Chinese hamster ovary (CHO) cells are widely used to produce recombinant proteins, including monoclonal antibodies (mAbs), through various process modes. While fed-batch (FB) processes have been the standard, a shift toward high-density perfusion processes is being driven by increased productivity, flexible facility footprints, and lower costs. Ensuring the clearance of process-related impurities, such as host cell proteins (HCPs), is crucial in biologics manufacturing.

LZTFL1 Upregulated by All-Trans Retinoic Acid during CD4+ T Cell Activation Enhances IL-5 Production.

Retinoic acids, which are metabolites of vitamin A, have been shown to be involved in multiple T cell effector responses through their binding to the retinoic acid receptor, a ligand-activated transcription factor. Because the molecular mechanism of regulation by retinoic acid is still not fully uncovered, we investigated the gene expression profile of all-trans retinoic acid (ATRA)-treated human CD4(+) T cells. Leucine zipper transcription factor-like 1 (LZTFL1) was upregulated by ATRA in a dose- and time-dependent manner.

Specificity of SecYEG for PhoA precursors and SecA homologs on SecA protein-conducting channels.

Previous studies showed that Escherichia coli membranes depleted of SecYEG are capable of translocating certain precursor proteins, but not other precursors such as pPhoA, indicating a differential requirement for SecYEG. In this study, we examined the role of SecYEG in pPhoA translocation using a purified reconstituted SecA-liposomes system. We found that translocation of pPhoA, in contrast to that of pOmpA, requires the presence of purified SecYEG.

Escherichia coli membranes depleted of SecYEG elicit SecA-dependent ion-channel activity but lose signal peptide specificity.

We have developed a sensitive method to detect the opening of SecA-dependent, protein-conducting channels in Xenopus oocytes. In this study, we determined the ionic current activities of the SecA-dependent channel from membrane vesicles depleted of SecYEG. We found that these SecYEG-depleted membranes produced SecA-dependent ionic currents in the oocytes, as did membranes containing SecYEG.

Negative regulation of human U6 snRNA promoter by p38 kinase through Oct-1.

Recruitment of Oct-1 protein to the octamer sequence of U6 promoter is critical for optimal transcription by RNA polymerase III. Here we report that p38 kinase inhibitors, SB202190 and SB203580, stimulated U6 promoter activity and this stimulation can be observed only in the presence of octamer sequence. SB202190-treated cell nuclear extract had about 50% increase in Oct-1 binding activity suggesting that the increased U6 promoter activity by p38 kinase inhibitor is mediated through Oct-1.

LIM kinase 1 - dependent cofilin 1 pathway and actin dynamics mediate nuclear retinoid receptor function in T lymphocytes.

Background: It is known that retinoid receptor function is attenuated during T cell activation, a phenomenon that involves actin remodeling, suggesting that actin modification may play a role in such inhibition. Here we have investigated the role of actin dynamics and the effect of actin cytoskeleton modifying agents on retinoid receptor-mediated transactivation.

Results: Agents that disturb the F-actin assembly or disassembly attenuated receptor-mediated transcription indicating that actin cytoskeletal homeostasis is important for retinoid receptor function.

Electrophysiological studies in Xenopus oocytes for the opening of Escherichia coli SecA-dependent protein-conducting channels.

Protein translocation in Escherichia coli requires protein-conducting channels in cytoplasmic membranes to allow precursor peptides to pass through with adenosine triphosphate (ATP) hydrolysis. Here, we report a novel, sensitive method that detects the opening of the SecA-dependent protein-conducting channels at the nanogram level. E.