Prefrontal Cortex HCN1 Channels Enable Intrinsic Persistent Neural Firing and Executive Memory Function

In many cortical neurons, HCN1 channels are the major contributors to I(h), the hyperpolarization-activated current, which regulates the intrinsic properties of neurons and shapes their integration of synaptic inputs, paces rhythmic activity, and regulates synaptic plasticity. Here, we examine the physiological role of I(h) in deep layer pyramidal neurons in mouse prefrontal cortex (PFC), focusing on persistent activity, a form of sustained firing thought to be important for the behavioral function of the PFC during working memory tasks. We find that HCN1 contributes to the intrinsic persistent firing that is induced by a brief depolarizing current stimulus in the presence of muscarinic agonists. Deletion of HCN1 or acute pharmacological blockade of I(h) decreases the fraction of neurons capable of generating persistent firing. The reduction in persistent firing is caused by the membrane hyperpolarization that results from the deletion of HCN1 or I(h) blockade, rather than a specific role of the hyperpolarization-activated current in generating persistent activity. In vivo recordings show that deletion of HCN1 has no effect on up states, periods of enhanced synaptic network activity. Parallel behavioral studies demonstrate that HCN1 contributes to the PFC-dependent resolution of proactive interference during working memory. These results thus provide genetic evidence demonstrating the importance of HCN1 to intrinsic persistent firing and the behavioral output of the PFC. The causal role of intrinsic persistent firing in PFC-mediated behavior remains an open question

PDK1 regulation of mTOR and hypoxia-inducible factor 1 integrate metabolism and migration of CD8+ T cells.

mTORC1 (mammalian target of rapamycin complex 1) controls transcriptional programs that determine CD8+ cytolytic T cell (CTL) fate. In some cell systems, mTORC1 couples phosphatidylinositol-3 kinase (PI3K) and Akt to the control of glucose uptake and glycolysis. However, PI3K-Akt-independent mechanisms control glucose metabolism in CD8+ T cells, and the role of mTORC1 has not been explored. The present study now demonstrates that mTORC1 activity in CD8+ T cells is not dependent on PI3K or Akt but is critical to sustain glucose uptake and glycolysis in CD8+ T cells. We also show that PI3K- and Akt-independent pathways mediated by mTORC1 regulate the expression of HIF1 (hypoxia-inducible factor 1) transcription factor complex. This mTORC1-HIF1 pathway is required to sustain glucose metabolism and glycolysis in effector CTLs and strikingly functions to couple mTORC1 to a diverse transcriptional program that controls expression of glucose transporters, multiple rate-limiting glycolytic enzymes, cytolytic effector molecules, and essential chemokine and adhesion receptors that regulate T cell trafficking. These data reveal a fundamental mechanism linking nutrient and oxygen sensing to transcriptional control of CD8+ T cell differentiation

Expression Patterns of the Transcription Factor AP-2α During Hair Follicle Morphogenesis and Cycling

AP-2α is a member of a family of transcription factors expressed in cells of the epithelial and neural crest lineage. AP-2α plays an essential role in embryonic development and in regulation of epithelial gene transcription. To further characterize the role of AP-2α in skin biology, we assessed its expression in the skin of C57BL/6J mice during defined stages of hair follicle morphogenesis and cycling. During early hair follicle morphogenesis, AP-2α was upregulated in the epidermal placode, in the basal keratinocytes of the hair follicle bud, and then in the inner root sheath. The follicular papilla cells underwent a brief upregulation of AP-2α expression during the initiation of hair shaft formation and active hair follicle downward growth. Completion of hair follicle morphogenesis was associated with a marked reduction of AP-2α immunoreactivity in the lower portion of the hair follicle including both epithelial and mesenchymal compartments. In adolescent mouse skin, consistently strong AP-2α expression was found in the basal keratinocytes of the epidermis, in the hair follicle infundibulum, and in the sebocytes. In the follicular papilla, AP-2α was weakly expressed in telogen, significantly upregulated in early anagen, then gradually declined, and reappeared again in middle catagen. In the inner root sheaths, AP-2α expression was detected during early and middle anagen and during middle catagen stages. Prominent AP-2α expression was also seen in the zone of club hair formation. Therefore, AP-2α upregulation in both epithelial and mesenchymal hair follicle compartments was coordinated with initiation of major remodeling processes. Our findings support the use of the hair follicle as a model to explore the role of AP-2α in physiologic remodeling of developing organs and in reciprocal ectodermal–mesenchymal interactions

Epidermal expression of the truncated prelamin A causing Hutchinson–Gilford progeria syndrome: effects on keratinocytes, hair and skin

Hutchinson–Gilford progeria syndrome (HGPS) is an accelerated aging disorder caused by point mutation in LMNA encoding A-type nuclear lamins. The mutations in LMNA activate a cryptic splice donor site, resulting in expression of a truncated, prenylated prelamin A called progerin. Expression of progerin leads to alterations in nuclear morphology, which may underlie pathology in HGPS. We generated transgenic mice expressing progerin in epidermis under control of a keratin 14 promoter. The mice had severe abnormalities in morphology of skin keratinocyte nuclei, including nuclear envelope lobulation and decreased nuclear circularity not present in transgenic mice expressing wild-type human lamin A. Primary keratinocytes isolated from these mice had a higher frequency of nuclei with abnormal shape compared to those from transgenic mice expressing wild-type human lamin A. Treatment with a farnesyltransferase inhibitor significantly improved nuclear shape abnormalities and induced the formation of intranuclear foci in the primary keratinocytes expressing progerin. Similarly, spontaneous immortalization of progerin-expressing cultured keratinocytes selected for cells with normal nuclear morphology. Despite morphological alterations in keratinocyte nuclei, mice expressing progerin in epidermis had normal hair grown and wound healing. Hair and skin thickness were normal even after crossing to Lmna null mice to reduce or eliminate expression of normal A-type lamins. Although progerin induces significant alterations in keratinocyte nuclear morphology that are reversed by inhibition of farnesyltransferasae, epidermal expression does not lead to alopecia or other skin abnormalities typically seen in human subjects with HGPS

Endoscopic endonasal transclival removal of tumors of the clivus and anterior region of the posterior cranial fossa (results of surgical treatment of 140 patients)

Abstract Background Until recently, tumors of the clivus and the anterior region of the posterior cranial fossa were considered extremely difficult to access and often inoperable using standard transcranial approaches. With the introduction into the neurosurgical practice of minimally invasive methods utilizing endoscopic techniques, it became possible to effectively remove hard-to-reach tumors, including central tumors of the anterior region of the posterior cranial fossa. Methods From 2008 to the present time, the inpatient institution has operated on 140 patients with various tumors of the base of the skull, localized to the clivus and anterior region of the posterior cranial fossa (65 men and 75 women). The age of patients ranged from 3 to 74 years. Tumor distribution according to the histopathological features was as follows: chordomas, 103 (73.57%); meningiomas, 12 (8.57%); pituitary adenomas, 9 (6.43%); fibrous dysplasia, 4 (2.86%); cholesteatoma, 3 (2.14%); craniopharyngiomas, 2 (1.43%); plasmacytomas, 2 (1.43%); and other tumors (giant cell tumor, neurohypophyseal glioma, osteoma, carcinoid, chondroma), 5 (3.57%). The tumors had the following size distribution: giant (more than 60 mm), 35 (25%); large (35–59 mm), 83 (59.3%); medium (21–35 mm), 21 (15%); and small (less than 20 mm), 1 (0.7%). In 11 cases, intraoperative monitoring of the cranial nerves was performed (21 cranial nerves were identified). Results Upper, middle, and lower transclival approaches provide access to the anterior surface of the upper, middle, and lower neurovascular complexes of the posterior cranial fossa. The chordoma cases were distributed as follows according to extent of removal: total removal, 68 (66.02%); subtotal removal, 25 (24.27%); and partial removal, 10 (9.71%). The adenomas of the pituitary gland were removed totally in 6 cases, subtotally in 1 case and partially in 2 cases. The meningiomas were removed totally in 1 case, subtotally in 5 cases, and partially in 5 cases, with less than 50% of the tumor removed in 1 case. Other tumors (cholesteatoma, craniopharyngioma, fibrous dysplasia, giant cell tumor, glioma of the neurohypophysis, osteoma, plasmacytoma, carcinoid, and chondroma) were removed totally in 9 cases and subtotally in 7 cases. Postoperative CSF leaks occurred in 9 cases (6.43%) and meningitis in 13 cases (9.29%). Oculomotor disorders developed in 19 patients (13.57%), 12 of which regressed during the period from 4 to 38 days after surgery, and 7 of which were permanent. In 2 cases, surgical treatment had a lethal outcome (1.43%). Conclusion The endoscopic endonasal transclival approach can be used to obtain access to the centrally located tumors of the posterior cranial fossa. It is an alternative to transcranial approaches in the surgical treatment of tumors of the clivus. The results of using this approach are comparable with the results of transcranial and transfacial approaches and, in some cases, surpass them in effectiveness. The extended endoscopic endonasal posterior (transclival) approach, considering its minimally invasive nature, allows fora radical and low-risk (in terms of postoperative complications and lethality) removal of various skull base tumors of central localization with the involvement and without the involvement of the clivus, which, until recently, were considered to be almost inoperable

Retinoic acid co-treatment aggravates severity of dioxin-induced skin lesions in hairless mice via induction of inflammatory response

Exposure to toxic halogenated polyaromatic hydrocarbons, of which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most potent, induces diverse skin pathologies in humans, including chloracne, hyperkeratosis, hamartomas, etc. While the toxic effects of TCDD have been extensively studied, effective approaches to their treatment are still lacking. Retinoids are commonly used in therapy of acneiform skin diseases. In vitro, retinoids elicit antagonistic effects on keratinocyte differentiation and proliferation, as compared to TCDD, suggesting their potential in treatment of TCDD-induced skin lesions. Nevertheless, the modulation of TCDD activity in skin by retinoids in vivo was never reported. We have used N-TERT keratinocyte cell line and hairless (hr) mice to determine if retinoic acid (RA) can lessen or reverse TCDD-induced effects in vitro and in vivo. RA co-treatment suppressed TCDD-induced changes in the expression of differentiation-associated genes and N-TERT keratinocyte viability in vitro. However, in hairless mice (in vivo), RA/TCDD co-treatment produced more severe effects, than treatment with either of the two compounds individually. RA/TCDD co-application to mouse skin strongly stimulated keratinocyte proliferation, resulting in dramatic epidermal hyperplasia. It has also led to massive immune cell infiltration into the dermis, and increased mRNA expression of inflammation markers, including IL1β, IL6 and S100A7. Thus, retinoids not only appeared ineffective in treatment of TCDD-induced skin lesions in hairless mice, but also resulted in their exaggeration. These in vivo results question previous cell culture-based claims that RA may reduce TCDD-induced skin effects and caution against the reliance on in vitro data in TCDD toxicology research. •Treatment with retinoic acid (RA) is ineffective for dioxin-induced skin lesions in mice.•Co-treatment with dioxin and RA results in psoriasis-like phenotype not seen under treatment with either compound alone.•Strong inflammation is the most prominent effect induced by combined treatment with dioxin and RA

Fibroblasts and polymer composition are essential for bioengineering of airway epithelium on nonwoven scaffolds

To make tissue engineering a truly effective tool, it is necessary to understand how the patterns of specific tissue development are modulated by and depend on the artificial environment. Even the most advanced approaches still do not fully meet the requirements of practical engineering of tracheobronchial epithelium. This study aimed to test the ability of the synthetic and natural nonwoven scaffolds to support the formation of morphological sound airway epithelium including the basement membrane (BM). We also sought to identify the potential role of fibroblasts in this process. Our results showed that nonwoven scaffolds are generally suitable for producing well-differentiated tracheobronchial epithelium (with cilia and goblet cells), while the structure and functionality of the equivalents appeared to be highly dependent on the composition of the scaffolds. Unlike natural scaffolds, synthetic ones supported the formation of the epithelium only when epithelial cells were cocultured with fibroblasts. Fibroblasts also appeared to be obligatory for basal lamina formation, regardless of the type of the nonwoven material used. However, even in the presence of fibroblasts, the synthetic scaffolds were unable to support the formation of the epithelium and of the BM (in particular, basal lamina) as effectively as the natural scaffolds did.</p