Translational and post-translational control of human naïve versus primed pluripotency

Deciphering the regulatory network for human naive and primed pluripotency is of fundamental theoretical and applicable significance. Here, by combining quantitative proteomics, phosphoproteomics, and acetylproteomics analyses, we revealed RNA processing and translation as the most differentially regulated processes between naive and primed human embryonic stem cells (hESCs). Although glycolytic primed hESCs rely predominantly on the eukaryotic initiation factor 4E (eIF4E)-mediated cap-dependent pathway for protein translation, naive hESCs with reduced mammalian target of rapamycin complex (mTORC1) activity are more tolerant to eIF4E inhibition, and their bivalent metabolism allows for translating selective mRNAs via both eIF4E-dependent and eIF4E-independent/eIF4A2-dependent pathways to form a more compact naive proteome. Globally up-regulated proteostasis and down-regulated post-translational modifications help to further refine the naive proteome that is compatible with the more rapid cycling of naive hESCs, where CDK1 plays an indispensable coordinative role. These findings may assist in better understanding the unrestricted lineage potential of naive hESCs and in further optimizing conditions for future clinical applications

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RNA processing and translation are most different between naive and primed hESCs

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Glycolytic primed hESCs mainly rely on eIF4E-dependent translation

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Bivalent metabolism in naive hESCs promotes eIF4E-independent translation

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CDK1 is required for naive pluripotency partially by activating E-cadherin signaling

LSD1-mediated demethylation of OCT4 safeguards pluripotent stem cells by maintaining the transcription of PORE-motif-containing genes

Reversible lysine methylation is essential for regulating histones and emerges to critically regulate non-histone proteins as well. Here we show that the master transcription factor OCT4 in pluripotent stem cells (PSCs) was methylated at multiple lysine residues. LSD1 that is highly expressed in PSCs can directly interact with and demethylate OCT4 at lysine 222 (K222) in the flexible linker region. Reduced LSD1 activity led to the methylation of OCT4-K222 that diminished the differentiation potential of PSCs while facilitating proteasome-independent degradation of OCT4 proteins. Furthermore, site-specifically replacing K222 with phenylalanine to mimic the constitutively methylated lysine promoted the 'locked-in' mode engagement of the OCT4 PORE-homodimers that tightly bind to and block the transcription of multiple PORE-motif-containing target genes regulating cell fate determination and cell junction organization, and thereby reducing the pluripotency of PSCs. Thus, LSD1-mediated demethylation of OCT4 plays a crucial role in restricting the 'locked-in' mode binding of OCT4 PORE-homodimers to the PORE-motif-containing genes and thereby maintaining their transcription to safeguard the pluripotency of PSCs.

Combined inhibition of JAK1/2 and DNMT1 by newly identified small-molecule compounds synergistically suppresses the survival and proliferation of cervical cancer cells

Despite substantial advances in treating cervical cancer (CC) with surgery, radiation and chemotherapy, patients with advanced CC still have poor prognosis and significantly variable clinical outcomes due to tumor recurrence and metastasis. Therefore, to develop more efficacious and specific treatments for CC remains an unmet clinical need. In this study, by virtual screening the SPECS database, we identified multiple novel JAK inhibitor candidates and validated their antitumor drug efficacies that were particularly high against CC cell lines. AH057, the best JAK inhibitor identified, effectively blocked the JAK/STAT pathways by directly inhibiting JAK1/2 kinase activities, and led to compromised cell proliferation and invasion, increased apoptosis, arrested cell cycles, and impaired tumor progression in vitro and in vivo. Next, by screening the Selleck chemical library, we identified SGI-1027, a DNMT1 inhibitor, as the compound that displayed the highest synergy with AH057. By acting on a same set of downstream effector molecules that are dually controlled by JAK1/2 and DNMT1, the combination of AH057 with SGI-1027 potently and synergistically impaired CC cell propagation via dramatically increasing apoptotic cell death and cell-cycle arrest. These findings establish a preclinical proof of concept for combating CC by dual targeting of JAK1/2 and DNMT1, and provide support for launching a clinical trial to evaluate the efficacy and safety of this drug combination in patients with CC and other malignant tumors.

Endogenous authentic OCT4A proteins directly regulate FOS/AP-1 transcription in somatic cancer cells

OCT4A is well established as a master transcription factor for pluripotent stem cell (PSC) self-renewal and a pioneer factor for initiating somatic cell reprogramming, yet its presence and functionality in somatic cancer cells remain controversial and obscure. By combining the CRISPR-Cas9-based gene editing with highly specific PCR assays, highly sensitive immunoassays, and mass spectrometry, we provide unequivocal evidence here that full-length authentic OCT4A transcripts and proteins were both present in somatic cancer cells, and OCT4A proteins were heterogeneously expressed in the whole cell population and when expressed, they are predominantly localized in cell nucleus. Despite their extremely low abundance (approximately three orders of magnitude lower than in PSCs), OCT4A proteins bound to the promoter/enhancer regions of the AP-1 transcription factor subunit c-FOS gene and critically regulated its transcription. Knocking out OCT4A in somatic cancer cells led to dramatic reduction of the c-FOS protein level, aberrant AP-1 signaling, dampened self-renewal capacity, deficient cell migration that were associated with cell growth retardation in vitro and in vivo, and their enhanced sensitivity to anticancer drugs. Taken together, we resolve the long-standing controversy and uncertainty in the field, and reveal a fundamental role of OCT4A protein in regulating FOS/AP-1 signaling-centered genes that mediate the adhesion, migration, and propagation of somatic cancer cells.

Cell cycle and pluripotency: Convergence on octamer‑binding transcription factor 4 (Review)

Embryonic stem cells (ESCs) have unlimited expansion potential and the ability to differentiate into all somatic cell types for regenerative medicine and disease model studies. Octamer-binding transcription factor 4 (OCT4), encoded by the POU domain, class 5, transcription factor 1 gene, is a transcription factor vital for maintaining ESC pluripotency and somatic reprogramming. Many studies have established that the cell cycle of ESCs is featured with an abbreviated G1 phase and a prolonged S phase. Changes in cell cycle dynamics are intimately associated with the state of ESC pluripotency, and manipulating cell-cycle regulators could enable a controlled differentiation of ESCs. The present review focused primarily on the emerging roles of OCT4 in coordinating the cell cycle progression, the maintenance of pluripotency and the glycolytic metabolism in ESCs.

Brain substrates underlying auditory speech priming in healthy listeners and listeners with schizophrenia

BACKGROUND

Under 'cocktail party' listening conditions, healthy listeners and listeners with schizophrenia can use temporally pre-presented auditory speech-priming (ASP) stimuli to improve target-speech recognition, even though listeners with schizophrenia are more vulnerable to informational speech masking.

METHOD

Using functional magnetic resonance imaging, this study searched for both brain substrates underlying the unmasking effect of ASP in 16 healthy controls and 22 patients with schizophrenia, and brain substrates underlying schizophrenia-related speech-recognition deficits under speech-masking conditions.

RESULTS

In both controls and patients, introducing the ASP condition (against the auditory non-speech-priming condition) not only activated the left superior temporal gyrus (STG) and left posterior middle temporal gyrus (pMTG), but also enhanced functional connectivity of the left STG/pMTG with the left caudate. It also enhanced functional connectivity of the left STG/pMTG with the left pars triangularis of the inferior frontal gyrus (TriIFG) in controls and that with the left Rolandic operculum in patients. The strength of functional connectivity between the left STG and left TriIFG was correlated with target-speech recognition under the speech-masking condition in both controls and patients, but reduced in patients.

CONCLUSIONS

The left STG/pMTG and their ASP-related functional connectivity with both the left caudate and some frontal regions (the left TriIFG in healthy listeners and the left Rolandic operculum in listeners with schizophrenia) are involved in the unmasking effect of ASP, possibly through facilitating the following processes: masker-signal inhibition, target-speech encoding, and speech production. The schizophrenia-related reduction of functional connectivity between the left STG and left TriIFG augments the vulnerability of speech recognition to speech masking.

Brain substrates of perceived spatial separation between speech sources under simulated reverberant listening conditions in schizophrenia

BACKGROUND

People with schizophrenia recognize speech poorly under multiple-people-talking (informational masking) conditions. In reverberant environments, direct-wave signals from a speech source are perceptually integrated with the source reflections (the precedence effect), forming perceived spatial separation (PSS) between different sources and consequently improving target-speech recognition against informational masking. However, the brain substrates underlying the schizophrenia-related vulnerability to informational masking and whether schizophrenia affects the unmasking effect of PSS are largely unknown.

METHOD

Using psychoacoustic testing and functional magnetic resonance imaging, respectively, the speech recognition under either the PSS or perceived spatial co-location (PSC) condition and the underlying brain substrates were examined in 20 patients with schizophrenia and 16 healthy controls.

RESULTS

Speech recognition was worse in patients than controls. Under the PSS (but not PSC) condition, speech recognition was correlated with activation of the superior parietal lobule (SPL), and target speech-induced activation of the SPL, precuneus, middle cingulate cortex and caudate significantly declined in patients. Moreover, the separation (PSS)-against-co-location (PSC) contrast revealed (1) activation of the SPL, precuneus and anterior cingulate cortex in controls, (2) suppression of the SPL and precuneus in patients, (3) activation of the pars triangularis of the inferior frontal gyrus and middle frontal gyrus in both controls and patients, (4) activation of the medial superior frontal gyrus in patients, and (5) impaired functional connectivity of the SPL in patients.

CONCLUSIONS

Introducing the PSS listening condition efficiently reveals both the brain substrates underlying schizophrenia-related speech-recognition deficits against informational masking and the schizophrenia-related neural compensatory strategy for impaired SPL functions.

4-[(1H-imidazol-4-yl) methyl] benzamidines and benzylamidines: novel antagonists of the histamine H3 receptor

A series of amidine substituted phenyl-, benzyl-, and phenethylimidazoles based on the known H3 agonist SK&F 91606 (4) has been synthesized and tested as ligands for the histamine H3 receptor. Insertion of a phenyl ring between the imidazole ring and the amidine moiety produces antagonists. The benzyl series was found to be the most potent and was further investigated. Compounds 9c and 18 (entries 5 and 12, Table 1) are potent ligands for the H3 receptor with K(i) values of 16 nM and 7.2 nM respectively. In vivo, both compounds were shown to be equipotent to thioperamide (2), the standard H3 antagonist.