Distinct transcriptional programs of SOX2 in different types of small cell lung cancers

SOX2 is recognized as an oncogene in human small cell lung cancer (SCLC), which is an aggressive neuroendocrine (NE) tumor. However, the role of SOX2 in SCLC is not completely understood, and strategies to selectively target SOX2 in SCLC cells remain elusive. Here, we show, using next-generation sequencing, that SOX2 expressed in the ASCL1-high SCLC (SCLC-A) subtype cell line is dependent on ASCL1, which is a lineage-specific transcriptional factor, and is involved in NE differentiation and tumorigenesis. ASCL1 recruits SOX2, which promotes INSM1 and WNT11 expression. Immunohistochemical studies revealed that SCLC tissue samples expressed SOX2, ASCL1, and INSM1 in 18 out of the 30 cases (60%). Contrary to the ASCL1-SOX2 signaling axis controlling SCLC biology in the SCLC-A subtype, SOX2 targets distinct genes such as those related to the Hippo pathway in the ASCL1-negative, YAP1-high SCLC (SCLC-Y) subtype. Although SOX2 knockdown experiments suppressed NE differentiation and cell proliferation in the SCLC-A subtype, they did not sufficiently impair the growth of the SCLC-Y subtype cell lines in vitro and ex vivo. The present results support the importance of the ASCL1-SOX2 axis as a main subtype of SCLC, and suggest the therapeutic potential of targeting the ASCL1-SOX2 axis.

Establishment of bone marrow-derived M-CSF receptor-dependent self-renewing macrophages

Recent studies have revealed that tissue macrophages are derived from yolk sac precursors or fetal liver monocytes, in addition to bone marrow monocytes. The relative contribution of these cells to the tissue macrophage pool is not fully understood, but embryo-derived cells are supposed to be more important because of their capacity to self-renew. Here, we show the presence of adult bone marrow-derived macrophages that retain self-renewing capacity. The self-renewing macrophages were readily obtained by long-term culture of mouse bone marrow cells with macrophage colony-stimulating factor (M-CSF), a key cytokine for macrophage development. They were non-tumorigenic and proliferated in the presence of M-CSF in unlimited numbers. Despite several differences from non-proliferating macrophages, they retained many features of cells of the monocytic lineage, including the differentiation into dendritic cells or osteoclasts. Among the transcription factors involved in the self-renewal of embryonic stem cells, Krüppel-like factor 2 (KLF2) was strongly upregulated upon M-CSF stimulation in the self-renewing macrophages, which was accompanied by the downregulation of MafB, a transcription factor that suppresses KLF2 expression. Indeed, knockdown of KLF2 led to cell cycle arrest and diminished cell proliferation in the self-renewing macrophages. Our new cell model would be useful to unravel differences in phenotype, function, and molecular mechanism of proliferation among self-renewing macrophages with different origins.

An Avulsed Tooth Detected Prior to Insertion of a Laryngeal Mask Airway

This case report describes the importance of inspecting the hypopharynx via direct laryngoscopy prior to laryngeal mask airway (LMA) insertion during induction of general anesthesia for dental patients with special needs. A 51-year-old man with cerebral palsy underwent induction of general anesthesia for dental extractions and subsequently was noted to be missing a tooth. Prompt inspection of the airway via direct laryngoscopy revealed the tooth resting within the pharynx, which was subsequently retrieved, prior to insertion of the LMA. Visual inspection of the oropharynx and hypopharynx by laryngoscopy prior to LMA insertion can be useful in preventing accidental aspiration and ingestion of foreign bodies, particularly with certain high-risk patients. Use of laryngoscopy should also be considered if an object is lost or possibly impinging upon the airway.

Anesthetic Management of a Patient With a Vagal Nerve Stimulator

Vagal nerve stimulation (VNS) is an established adjunctive treatment for patients with refractory epilepsy. VNS is effective in many cases, but few patients achieve complete elimination of seizures. Furthermore, VNS can cause respiratory complications, such as obstructive sleep apnea. This report describes the successful anesthetic management of a 28-year-old woman with a VNS device who underwent dental treatment under general anesthesia. She was morbidly obese and had undergone placement of a VNS device secondary to drug-resistant epilepsy 2 years prior but continued to experience daily epileptic seizures. Because of concerns about the risk of perioperative epileptic seizures and apneic events, use of the dedicated VNS device magnet was planned if such complications occurred. Total intravenous anesthesia was induced with propofol and remifentanil and a bispectral index sensor was used to help monitor brain wave activity for evidence of seizures along with the depth of anesthesia. Postoperatively, the patient received positional therapy and supplemental oxygen while being closely monitored in recovery. The anesthetic course was completed uneventfully without need of the VNS magnet. A thorough understanding of the mechanics of a VNS device, including proper use of the VNS magnet, is critical for an anesthesiologist during the perioperative period.

Mesenchymal-epithelial transition regulates initiation of pluripotency exit before gastrulation

The pluripotent epiblast gives rise to all tissues and organs in the adult body. Its differentiation starts at gastrulation, when the epiblast generates mesoderm and endoderm germ layers through epithelial-mesenchymal transition (EMT). Although gastrulation EMT coincides with loss of epiblast pluripotency, pluripotent cells in development and in vitro can adopt either mesenchymal or epithelial morphology. The relationship between epiblast cellular morphology and its pluripotency is not well understood. Here, using chicken epiblast and mammalian pluripotency stem cell (PSC) models, we show that PSCs undergo a mesenchymal-epithelial transition (MET) prior to EMT-associated pluripotency loss. Epiblast MET and its subsequent EMT are two distinct processes. The former, a partial MET, is associated with reversible initiation of pluripotency exit, whereas the latter, a full EMT, is associated with complete and irreversible pluripotency loss. We provide evidence that integrin-mediated cell-matrix interaction is a key player in pluripotency exit regulation. We propose that epiblast partial MET is an evolutionarily conserved process among all amniotic vertebrates and that epiblast pluripotency is restricted to an intermediate cellular state residing between the fully mesenchymal and fully epithelial states.

Bilateral Parkinson's disease model rats exhibit hyperalgesia to subcutaneous formalin administration into the vibrissa pad

We bilaterally injected 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle of rats and developed bilateral Parkinson’s disease (PD) model rats in order to experimentally investigate the neural mechanisms underlying the alteration of nociception in the orofacial region of patients with PD. We explored the effects of dopamine depletion on nociception by investigating behavioral responses (face rubbing) triggered by subcutaneous administration of formalin into the vibrissa pad. We also assessed the number of c-Fos–immunoreactive (c-Fos-IR) cells in the superficial layers of the trigeminal spinal subnucleus caudalis (Vc). Subcutaneous formalin administration evoked a two-phase increase in face rubbing. We observed the first increase 0–5 min after formalin administration (first phase) and the second increase 10–60 min after administration (second phase). The number of face rubbing behaviors of 6OHDA–injected rats did not significantly change compared with saline–injected rats in both phases. Significant increase of c-Fos-IR cells in the Vc was found in 6-OHDA–injected rats after formalin administration compared with those in saline–injected rats after formalin administration. We also assessed expression of c-Fos-IR cells in the paraventricular nucleus (PVN), and significant decrease of c-Fos-IR cells in the PVN of 6-OHDA–injected rats was found. Taken together, these findings suggest that bilateral dopaminergic denervation evoked by 6-OHDA administration causes hyperalgesia in the trigeminal region and the PVN may be involved in the hyperalgesia.

A novel surgical strategy for the resection of duodenal gastrointestinal stromal tumours located close to the duodenal ampulla: a case report

Although the optimal surgical procedure for the resection of duodenal gastrointestinal stromal tumours has not yet been characterised due to the low prevalence of these tumours and the anatomical complexity of the duodenopancreatic region, difficult surgical procedures such as pancreaticoduodenectomy are often proposed for stromal tumours located in the second portion of the duodenum. Our case report highlights a novel surgical strategy that can be implemented as an alternative to pancreaticoduodenectomy for such tumours close to the duodenal ampulla. A 70-year-old man incidentally diagnosed with a stromal tumour close to the duodenal ampulla in the second portion of the duodenum underwent local resection guided by an endoscopic nasobiliary drainage tube with primary closure. This tube was converted to a percutaneous trans-small intestinal biliary drainage tube during the procedure to prevent biliary leakage biliary stasis due to swelling of the duodenal ampulla. He also underwent a simple distal gastrectomy with Roux-en-Y reconstruction. This resulted in successful R0 resection. There were no procedure-related complications or post-surgery weight changes. Our simple novel surgical strategy may therefore be useful for avoiding pancreaticoduodenectomy and maintaining quality of life in patients with stromal tumours close to the duodenal ampulla.

Age-based prediction of uncuffed tracheal tube size in children to prevent inappropriately large tube selection: a retrospective analysis

Background

This study aims to validate our previously reported prediction technique for uncuffed tracheal tube (TT) sizes in children younger than 2 years of age based on a calculated outer diameter (OD_Cal, mm) in each patient according to the regression equation OD_Cal = 0.00223 × age (day) + 4.88 and to investigate a better method to select initial TT sizes to decrease re-intubation frequency, especially since large tubes can damage the trachea.

Methods

We included patients younger than 2 years of age who underwent oral surgery under general anesthesia with tracheal intubation between July 2011 and December 2016 at the Osaka University Dental Hospital. The OD of the actual TT and the age in days were extracted from anesthesia records. Agreement rates, estimated numbers of required tubes, and size reduction frequencies were compared to obtain recommended OD (OD_Rec) values in 2 selection groups: “average selection” in the range “nearest to the OD_Cal value (OD_Cal - 0.35 < OD_Rec ≤ OD_Cal + 0.35)” and “safe selection” in the range “nearest to the value below OD_Cal (OD_Cal - 0.7 < OD_Rec ≤ OD_Cal)”.

Results

The agreement rates for an OD_Rec in the average selection and safe selection groups were 60.8 and 55.1%, respectively (P = 0.001). The estimated number of required tubes per patient were 1.40 ± 0.51 and 1.47 ± 0.55 (P < 0.001), respectively. The estimated frequencies of size reductions were 13.3 and 4.0% (P < 0.001), respectively.

Conclusions

Because the size reduction frequency is lower despite a slightly higher number of required TTs, selecting an OD_Rec based on “safe selection” parameters is desirable to avoid complications due to intubation with larger TTs.

Klf5 suppresses ERK signaling in mouse pluripotent stem cells

Mouse embryonic stem cells (ESCs) are pluripotent stem cells, which have the ability to differentiate into all three germ layers: mesoderm, endoderm, and ectoderm. Proper levels of phosphorylated extracellular signal-regulated kinase (pERK) are critical for maintaining pluripotency, as elevated pERK evoked by fibroblast growth factor (FGF) receptor activation results in differentiation of ESCs, while, conversely, reduction of pERK by a MEK inhibitor maintains a pluripotent ground state. However, mechanisms underlying proper control of pERK levels in mouse ESCs are not fully understood. Here, we find that Klf5, a Krüppel-like transcription factor family member, is a component of pERK regulation in mouse ESCs. We show that ERK signaling is overactivated in Klf5-KO ESCs and the overactivated ERK in Klf5-KO ESCs is suppressed by the introduction of Klf5, but not Klf2 or Klf4, indicating a unique role for Klf5 in ERK suppression. Moreover, Klf5 regulates Spred1, a negative regulator of the FGF-ERK pathway. Klf5 also facilitates reprogramming of EpiSCs into a naïve state in combination with a glycogen synthase kinase 3 inhibitor and LIF, and in place of a MEK inhibitor. Taken together, these results show for the first time that Klf5 has a unique role suppressing ERK activity in mouse ESCs.

In vitro and in vivo characterization of the bifunctional μ and δ opioid receptor ligand UFP-505

BACKGROUND AND PURPOSE

Targeting more than one opioid receptor type simultaneously may have analgesic advantages in reducing side-effects. We have evaluated the mixed μ opioid receptor agonist/ δ opioid receptor antagonist UFP-505 in vitro and in vivo.

EXPERIMENTAL APPROACH

We measured receptor density and function in single μ, δ and μ /δ receptor double expression systems. GTPγ35 S binding, cAMP formation and arrestin recruitment were measured. Antinociceptive activity was measured in vivo using tail withdrawal and paw pressure tests following acute and chronic treatment. In some experiments, we collected tissues to measure receptor densities.

KEY RESULTS

UFP-505 bound to μ receptors with full agonist activity and to δ receptors as a low efficacy partial agonist At μ, but not δ receptors, UFP-505 binding recruited arrestin. Unlike morphine, UFP-505 treatment internalized μ receptors and there was some evidence for internalization of δ receptors. Similar data were obtained in a μ /δ receptor double expression system. In rats, acute UFP-505 or morphine, injected intrathecally, was antinociceptive. In tissues harvested from these experiments, μ and δ receptor density was decreased after UFP-505 but not morphine treatment, in agreement with in vitro data. Both morphine and UFP-505 induced significant tolerance.

CONCLUSIONS AND IMPLICATIONS

In this study, UFP-505 behaved as a full agonist at μ receptors with variable activity at δ receptors. This bifunctional compound was antinociceptive in rats after intrathecal administration. In this model, dual targeting provided no advantages in terms of tolerance liability.

LINKED ARTICLES

This article is part of a themed section on Emerging Areas of Opioid Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.14/issuetoc.

Overlapping functions of Krüppel-like factor family members: targeting multiple transcription factors to maintain the naïve pluripotency of mouse embryonic stem cells

Krüppel-like factors (Klfs) have a pivotal role in maintaining self-renewal of mouse embryonic stem cells (mESCs). The functions of three Klf family members (Klf2, Klf4 and Klf5) have been identified, and are suggested to largely overlap. For further dissection of their functions, we applied an inducible knockout system for these Klf family members and assessed the effects of combinatorial loss of function. As a result, we confirmed that any one of Klf2, Klf4 and Klf5 was sufficient to support self-renewal, whereas the removal of all three compromised it. The activity of any single transcription factor, except for a Klf family member, was not sufficient to restore self-renewal of triple-knockout mESCs. However, some particular combinations of transcription factors were capable of the restoration. The triple-knockout mESCs were successfully captured at primed state. These data indicate that the pivotal function of a Klf family member is transduced into the activation of multiple transcription factors in a naïve-state-specific manner.

The principles that govern transcription factor network functions in stem cells

Tissue-specific transcription factors primarily act to define the phenotype of the cell. The power of a single transcription factor to alter cell fate is often minimal, as seen in gain-of-function analyses, but when multiple transcription factors cooperate synergistically it potentiates their ability to induce changes in cell fate. By contrast, transcription factor function is often dispensable in the maintenance of cell phenotype, as is evident in loss-of-function assays. Why does this phenomenon, commonly known as redundancy, occur? Here, I discuss the role that transcription factor networks play in collaboratively regulating stem cell fate and differentiation by providing multiple explanations for their functional redundancy.

Co-precipitation molecules hemopexin and transferrin may be key molecules for fibrillogenesis in TTR V30M amyloidogenesis

The disease model of familial amyloidotic polyneuropathy—7.2-hMet30 mice—manifests amyloid deposition that consists of a human amyloidogenic mutant transthyretin (TTR) (TTR V30M). Our previous study found amyloid deposits in 14 of 27 7.2-hMet30 mice at 21–24 months of age. In addition, non-fibrillar TTR deposits were found in amyloid-negative 7.2hMet30 mice. These results suggested that TTR amyloidogenesis required not only mutant TTR but also an additional factor (or factors) as an etiologic molecule. To determine the differences in serum proteome in amyloid-positive and amyloid-negative mice in the 7.2-hMet30 model, we used proteomic analyses and studied serum samples obtained from these mice. Hemopexin (HPX) and transferrin (Tf) were detected in the serum samples from amyloid-positive mice and were also found in amyloid deposits via immunohistochemistry, but serum samples from amyloid-negative mice did not contain HPX and Tf. These two proteins were also not detected in non-fibrillar TTR deposits. In addition, in silico analyses suggested that HPX and Tf facilitate destabilization of TTR secondary structures and misfolding of TTR. These results suggest that HPX and Tf may be associated with TTR amyloidogenesis after fibrillogenesis in vivo.

Probing the OH Stretch in Different Local Environments in Liquid Water

We use resonant inelastic X-ray scattering (RIXS) to resolve vibrational losses corresponding to the OH stretch where the X-ray absorption process allows us to selectively probe different structural subensembles in liquid water. The results point to a unified interpretation of X-ray and vibrational spectroscopic data in line with a picture of two classes of structural environments in the liquid at ambient conditions with predominantly close-packed high-density liquid (HDL) and occasional local fluctuations into strongly tetrahedral low-density liquid (LDL).

Anaphylaxis with delayed appearance of skin manifestations during general anesthesia: two case reports

Background

Anaphylaxis is difficult to diagnose in the absence of skin or mucosal signs and symptoms. We report two cases of anaphylaxis under general anesthesia, in which the initial presentation was in the form of respiratory signs, followed by skin manifestations 10–15 min later. Diagnosis of anaphylaxis was delayed because skin symptoms were absent early on in the presentation.

Case presentation

In the first case, a 23-year-old male patient with jaw deformity was scheduled to undergo maxillary alveolar osteotomy. After intubation, auscultation indicated a sudden decrease in breath sounds, together with severe hypotension. Approximately 10 min later, flushing of the skin and urticaria on the thigh appeared and spread widely throughout the body. In the second case, a 21-year-old female patient with jaw deformity was scheduled to undergo maxillomandibular osteotomy. Twenty minutes after the start of dextran infusion, her lungs suddenly became difficult to ventilate, and oxygen saturation decreased to 90%. Approximately 15 min later, flushing of the skin and urticaria were observed.

Conclusion

In both cases, there was a time lag between the appearance of respiratory and skin symptoms, which resulted in a delay in the diagnosis, and hence, treatment of anaphylaxis. Our experience highlights the fact that it is difficult to diagnose anaphylaxis under general anesthesia.

Effective Dosage of Midazolam to Erase the Memory of Vascular Pain During Propofol Administration

Intravenous sedation with propofol is often administered to anxious patients in dental practice. Pain on injection of propofol is a common adverse effect. This study aimed to determine the age-adjusted doses of midazolam required to erase memory of vascular pain of propofol administration and assess whether the Ramsay Sedation Scale (RSS) after the pretreatment of midazolam was useful to predict amnesia of the vascular pain of propofol administration. A total of 246 patients with dental phobia requiring dental treatment under intravenous sedation were included. Patients were classified according to their age: 30s, 40s, 50s, and 60s. Three minutes after administration of a predetermined dose of midazolam, propofol was infused continuously. After completion of the dental procedure, patients were interviewed about the memory of any pain or discomfort in the injection site or forearm. The dosage of midazolam was determined using the Dixon up-down method. The first patient was administered 0.03 mg/kg, and if memory of vascular pain remained, the dosage was increased by 0.01 mg/kg for the next patient, and then if the memory was erased, the dosage was decreased by 0.01 mg/kg. The effective dosage of midazolam in 95% of each age group for erasing the memory of propofol vascular pain (ED95) was determined using logistic analysis. The accuracy of RSS to predict the amnesia of injection pain was assessed by receiver operating characteristic (ROC) analysis. The ED95 of midazolam to erase the memory of propofol vascular pain was 0.061 mg/kg in patients in their 30s, 0.049 mg/kg in patients in their 40s, 0.033 mg/kg in patients in their 50s, and 0.033 mg/kg in patients in their 60s. The area under the ROC curve was 0.31. The ED95 of midazolam required to erase the memory of propofol vascular pain demonstrated a downward trend with age. On the other hand, it was impossible to predict the amnesia of propofol vascular pain using the RSS.

Airway management for glossopexy in infants with micrognathia and obstructive breathing

STUDY OBJECTIVES

To identify airway management and tracheal intubation techniques for glossopexy in infants with preexisting airway obstruction under general anesthesia.

DESIGN

Retrospective, observational study.

SETTINGS

Operating room of a university hospital between January 2003 and March 2015. All operations were performed by oral and maxillofacial surgeons.

PATIENTS

Thirteen patients who received general anesthesia for glossopexy and reversal after 7 months.

MEASUREMENTS

The medical records of these infants were retrospectively examined to evaluate the following: age, sex, height and weight at surgery, preoperative airway status, tracheal intubation route (oral or nasal), method for inducing general anesthesia, method for establishing the airway during mask ventilation, apparatus used for tracheal intubation, Cormack-Lehane classification when using a Macintosh laryngoscope and video laryngoscope, and the need for airway placement after extubation.

RESULTS

Prone positioning and/or an airway of some kind before surgery were required in 38.5% of infants needing glossopexy. Difficult mask ventilation was common, occurring in 50% of the patients, and the incidence of airway placement during mask ventilation was significantly higher in infants with preoperative complete or incomplete obstruction (100%) than in infants with snoring (25%). Of these high-risk infants, 25% could not be intubated with a direct laryngoscope or Glidescope Cobalt and required fiberoptic intubation.

CONCLUSION

There are severe cases of infants with difficult mask ventilation and difficult tracheal intubation in which a fiberscope is required because video laryngoscopy fails to improve the view of the larynx.

Trigeminal nervous system sensitization by infraorbital nerve injury enhances responses in a migraine model

Background

Although the peripheral and central sensitizations of trigeminal nervous system may be one of the important factors of migraine, the precise mechanism is not fully understood. In this study, we examined the influence of the sensitization of the second division of the trigeminal nerve (V2) by chronic constriction injury (CCI) of the infraorbital nerve (ION) on migraine headache, using the capsaicin-induced migraine model.

Methods

Male Sprague-Dawley rats were assigned to four groups: (a) sham surgery and topical-dural vehicle application (Sham + Vehicle) group, (b) CCI-ION and topical-dural vehicle application (CCI-ION + Vehicle) group, (c) sham surgery and topical-dural capsaicin application (Sham + Capsaicin) group, (d) CCI-ION and topical-dural capsaicin application (CCI-ION + Capsaicin) group. Behavioral testing and immunohistochemical staining were performed.

Results

In the behavioral test, the Sham + Capsaicin group showed significantly longer duration of immobilization and shorter duration of exploration compared with the Sham + Vehicle group, which is similar to clinical features of migraine patients. Moreover, CCI-ION enhanced these effects in the CCI-ION + Capsaicin group. Immunohistochemical staining for phospho-extracellular signal-related kinase (pERK) in the trigeminal ganglion (TG) containing first and second divisions of the trigeminal nerve and the trigeminocervical complex (TCC) revealed that pERK expression was significantly increased in the CCI-ION + Capsaicin group compared with the other groups. However, comparing between effects of the peripheral and central sensitizations (in the TG and TCC), from our results, peripheral sensitization would play a much less or not significant role.

Conclusions

These data demonstrate that the sensitization of V2 could influence the activation and the sensitization of the first division of the trigeminal nerve in the TCC, subsequently exacerbating pain sensation and pain-related behaviors. We have shown for the first time that the existence of the central sensitization of V2 can be an exacerbating factor for migraine related nociceptive thresholds/activation.

Estrogens Exacerbate Nociceptive Pain via Up-Regulation of TRPV1 and ANO1 in Trigeminal Primary Neurons of Female Rats

Several trigeminal pain disorders show sex differences, and high levels of estrogens may underlie these differences. The interaction between transient receptor potential vanilloid 1 (TRPV1) and anoctamin 1 (ANO1) plays an important role in peripheral nociception. However, whether TRPV1 and ANO1 are involved in estrogen-modulated trigeminal pain sensitivity is unclear. In this study, we examined estradiol (E2) modulation of nociception through behavioral and immunohistological experiments after application of capsaicin (Cap), a selective TRPV1 agonist, onto the ocular surface in ovariectomized rats treated with high-dose E2 (HE) or low-dose E2 (LE) for 2 days. In addition, we used real-time PCR to study the effects of E2 on the expression levels of TRPV1 and ANO1 mRNA in trigeminal ganglia. In the behavioral experiment, the HE group showed significant potentiation of Cap-evoked nocifensive behavior compared with the LE group. Immunohistochemistry showed that Cap evoked a significantly greater number of cells that were immunoreactive for c-Fos, a marker of nociceptive activation, in the trigeminal subnucleus caudalis/upper cervical cord in the HE group than in the LE group. The number of c-Fos-immunoreactive cells in the ventral trigeminal interpolaris/caudalis were similar in the 2 groups. Real-time PCR showed that the levels of TRPV1 and ANO1 mRNA in the HE group were significantly higher than levels in the LE group. Thus, high levels of estrogens may be a risk factor for Cap-evoked nociceptive pain, and estrogen-dependent increases in TRPV1 and ANO1 are likely involved in modulating the nociceptive response in the trigeminal area.

The evolutionally-conserved function of group B1 Sox family members confers the unique role of Sox2 in mouse ES cells

BACKGROUND

In mouse ES cells, the function of Sox2 is essential for the maintenance of pluripotency. Since the Sox-family of transcription factors are well conserved in the animal kingdom, addressing the evolutionary origin of Sox2 function in pluripotent stem cells is intriguing from the perspective of understanding the origin of pluripotency.

RESULTS

Here we approach this question using a functional complementation assay in inducible Sox2-null ES cells. Assaying mouse Sox proteins from different Groups, we found that only Group B1 and Group G proteins were able to support pluripotency. Interestingly, invertebrate homologs of mammalian Group B1 Sox proteins were able to replace the pluripotency-associated function of mouse Sox2. Moreover, the mouse ES cells rescued by the Drosophila SoxNeuro protein are able to contribute to chimeric embryos.

CONCLUSIONS

These data indicate that the function of mouse Sox2 supporting pluripotency is based on an evolutionally conserved activity of the Group B1 Sox family. Since pluripotent stem cell population in developmental process could be regarded as the evolutional novelty in vertebrates, it could be regarded as a co-optional use of their evolutionally conserved function.