Roles of astrocytic sonic hedgehog production and its signal for regulation of the blood-brain barrier permeability.

Sonic hedgehog (Shh) is a secreted glycopeptide belonging to the hedgehog family that is essential for morphogenesis during embryonic development. The Shh signal is mediated by two membrane proteins, Patched-1 (Ptch-1) and Smoothened (Smo), following the activation of transcription factors such as Gli. Shh decreases the permeability of the blood-brain barrier (BBB) and plays a key role in its function. In the damaged brain, BBB function is remarkably disrupted. The BBB disruption causes brain edema and neuroinflammation resulting from the extravasation of serum components and the infiltration of inflammatory cells into the cerebral parenchyma. Multiple studies have suggested that astrocyte is a source of Shh and that astrocytic Shh production is increased in the damaged brain. In various experimental animal models of acute brain injury, Shh or Shh signal activators alleviate BBB disruption by increasing tight junction proteins in endothelial cells. Furthermore, activation of astrocytic Shh signaling reduces reactive astrogliosis, neuroinflammation, and increases the production of vascular protective factors, which alleviates BBB disruption in the damaged brain. These findings suggest that astrocytic Shh and Shh signaling protect BBB function in the damaged brain and that target drugs for Shh signaling are expected to be novel therapeutic drugs for acute brain injuries.

Range-wide genetic analysis of an endangered bumble bee (Bombus affinis, Hymenoptera: Apidae) reveals population structure, isolation by distance, and low colony abundance.

Declines in bumble bee species range and abundances are documented across multiple continents and have prompted the need for research to aid species recovery and conservation. The rusty patched bumble bee (Bombus affinis) is the first federally listed bumble bee species in North America. We conducted a range-wide population genetics study of B. affinis from across all extant conservation units to inform conservation efforts. To understand the species' vulnerability and help establish recovery targets, we examined population structure, patterns of genetic diversity, and population differentiation. Additionally, we conducted a site-level analysis of colony abundance to inform prioritizing areas for conservation, translocation, and other recovery actions. We find substantial evidence of population structuring along an east-to-west gradient. Putative populations show evidence of isolation by distance, high inbreeding coefficients, and a range-wide male diploidy rate of ~15%. Our results suggest the Appalachians represent a genetically distinct cluster with high levels of private alleles and substantial differentiation from the rest of the extant range. Site-level analyses suggest low colony abundance estimates for B. affinis compared to similar datasets of stable, co-occurring species. These results lend genetic support to trends from observational studies, suggesting that B. affinis has undergone a recent decline and exhibit substantial spatial structure. The low colony abundances observed here suggest caution in overinterpreting the stability of populations even where B. affinis is reliably detected interannually. These results help delineate informed management units, provide context for the potential risks of translocation programs, and help set clear recovery targets for this and other threatened bumble bee species.

A Residual N-Terminal Peptide Enhances Signaling of Depalmitoylated Hedgehog to the Patched Receptor.

During their biosynthesis, Sonic hedgehog (Shh) morphogens are covalently modified by cholesterol at the C-terminus and palmitate at the N-terminus. Although both lipids initially anchor Shh to the plasma membrane of producing cells, it later translocates to the extracellular compartment to direct developmental fates in cells expressing the Patched (Ptch) receptor. Possible release mechanisms for dually lipidated Hh/Shh into the extracellular compartment are currently under intense debate. In this paper, we describe the serum-dependent conversion of the dually lipidated cellular precursor into a soluble cholesteroylated variant (ShhC) during its release. Although ShhC is formed in a Dispatched- and Scube2-dependent manner, suggesting the physiological relevance of the protein, the depalmitoylation of ShhC during release is inconsistent with the previously postulated function of N-palmitate in Ptch receptor binding and signaling. Therefore, we analyzed the potency of ShhC to induce Ptch-controlled target cell transcription and differentiation in Hh-sensitive reporter cells and in the Drosophila eye. In both experimental systems, we found that ShhC was highly bioactive despite the absence of the N-palmitate. We also found that the artificial removal of N-terminal peptides longer than eight amino acids inactivated the depalmitoylated soluble proteins in vitro and in the developing Drosophila eye. These results demonstrate that N-depalmitoylated ShhC requires an N-peptide of a defined minimum length for its signaling function to Ptch.

Nile Tilapia (Oreochromis niloticus) Patched1 Mutations Disrupt Cardiovascular Development and Vascular Integrity through Smoothened Signaling.

Hedgehog (Hh) signaling is crucial in cardiovascular development and maintenance. However, the biological role of Patched1 (Ptch1), an inhibitory receptor of the Hh signaling pathway, remains elusive. In this study, a Ptch1 ortholog was characterized in Nile tilapia (Oreochromis niloticus), and its function was investigated through CRISPR/Cas9 gene knockout. When one-cell embryos were injected with CRISPR/Cas9 targeting ptch1, the mutation efficiency exceeded 70%. During 0-3 days post fertilization (dpf), no significant differences were observed between the ptch1 mutant group and the control group; at 4 dpf (0 day after hatching), about 10% of the larvae showed an angiogenesis defect and absence of blood flow; from 5 dpf, most larvae exhibited an elongated heart, large pericardial cavity, and blood leakage and coagulation, ultimately dying during the 6-8 dpf period due to the lack of blood circulation. Consistently, multiple differentially expressed genes related to angiogenesis, blood coagulation, and heart development were enriched in the ptch1 mutants. Furthermore, Smoothened (Smo) antagonist (cyclopamine) treatment of the ptch1 mutants greatly rescued the cardiovascular disorders. Collectively, our study suggests that Ptch1 is required for cardiovascular development and vascular integrity via Smo signaling, and excessive Hh signaling is detrimental to cardiovascular development.

Characterization of Sonic Hedgehog transcripts in the adult mouse brain: co-expression with neuronal and oligodendroglial markers.

In the adult mammalian brain, astrocytes are proposed to be the major Sonic Hedgehog (Shh)-responsive cells. However, the sources of the Shh molecule mediating activation of the pathway are still poorly characterized. The present work investigates the distribution and phenotype of cells expressing Shh mRNA in the adult mouse brain. Using single-molecule fluorescent in situ hybridization (smfISH), we report much broader expression of Shh transcripts in almost all brain regions than originally reported. We identify Shh mRNA in HuC/D+ neuronal populations, including GABAergic (glutamic acid decarboxylase 67, Gad67), cholinergic (choline acetyltransferase, ChAT), dopaminergic (tyrosine hydroxylase, TH), nitrergic (neuronal nitric oxide synthase, nNOS), and in a small population of oligodendroglial cells expressing Sox10 and Olig2 mRNA transcription factors. Further analysis of Shh mRNA in cerebral cortical and hypothalamic neurons suggests that Shh is also expressed by glutamatergic neurons. Interestingly, we did not observe substantial Desert Hedgehog and Indian Hedgehog mRNA signals, nor Shh signals in S100ß+ astrocytes and Iba1+ microglial cells. Collectively, the present work provides the most robust central map of Shh-expressing cells to date and underscores the importance of nitrergic neurons in regulating Shh availability to brain cells. Thus, our study provides a framework for future experiments aimed at better understanding of the functions of Shh signaling in the brain in normal and pathological states, and the characterization of novel regulatory mechanisms of the signaling pathway.

PTCH1-mutant human cerebellar organoids exhibit altered neural development and recapitulate early medulloblastoma tumorigenesis.

Patched 1 (PTCH1) is the primary receptor for the sonic hedgehog (SHH) ligand and negatively regulates SHH signalling, an essential pathway in human embryogenesis. Loss-of-function mutations in PTCH1 are associated with altered neuronal development and the malignant brain tumour medulloblastoma. As a result of differences between murine and human development, molecular and cellular perturbations that arise from human PTCH1 mutations remain poorly understood. Here, we used cerebellar organoids differentiated from human induced pluripotent stem cells combined with CRISPR/Cas9 gene editing to investigate the earliest molecular and cellular consequences of PTCH1 mutations on human cerebellar development. Our findings demonstrate that developmental mechanisms in cerebellar organoids reflect in vivo processes of regionalisation and SHH signalling, and offer new insights into early pathophysiological events of medulloblastoma tumorigenesis without the use of animal models.

Síndrome de Gorlin-Goltz. Diagnóstico molecular, nuevos tratamientos / Gorlin-Goltz syndrome. Molecular diagnosis, new treatments

Introducción: El síndrome de Gorlin-Goltz o síndrome de carcinoma de nevo basocelular es un desorden hereditario autosómico dominante que predispone principalmente a la proliferación de múltiples carcinomas basocelulares, queratoquistes odontogénicos y defectos del desarrollo, causados por la mutación del gen Patched localizado en el cromosoma 9. Presentación del caso: Se reporta un paciente con características de este síndrome, en la clínica de COMF de la UNAM. El diagnóstico fue basado en los estudios clínicos, imagenológicos y moleculares. Conclusiones: El conocimiento de esta enfermedad puede orientarnos a la sospecha diagnóstica de lesión quística o premaligna en forma oportuna, lo que permite prevenir complicaciones y brindar un tratamiento integral para así mejorar la calidad de vida de este tipo de pacientes (AU)

Introduction: Gorlin-Goltz syndrome or cell-based nevus carcinoma syndrome is an autosomal dominant inherited disorder that predisposes mainly to the proliferation of multiple basal cell carcinomas, maxillary keratocysts and developmental defects, caused by the mutation of the Patched gene located on chromosome 9. Case presentation: A patient with specific characteristics compatible with this syndrome was reported in the COMF Department of the UNAM. The diagnosis was based on clinical studies, radiology and genetic studies. Conclusions: Knowledge of this problem can guide us to the diagnostic suspicion in a timely manner, thus preventing complications, and to provide an improved integral treatment of the quality of life of this type of patients (AU)

Queratoquiste odontogenico recurrente en paciente con sindrome de Gorlin-Goltz / Recurrent odontogenic keratocyst in patient with Gorlin-Goltz Syndrome

RESUMEN El Síndrome de Gorlin-Goltz (SGG) es un desorden autosómico dominante, se caracteriza por presentar anomalías esqueléticas, Queratoquistes Odontogénicos (QQOs) múltiples y carcinoma de células basales. Se han realizado estudios comparativos de los QQOs asociados y no asociados al SGG, y se encontró la presencia de mayor número de quistes satélites, proliferaciones sólidas del epitelio, inflamaciones, calcificaciones, más intensa ac-tividad mitótica de las células epiteliales, y mayor recurrencia de los QQOs asociados al SGG. El propósito de este reporte de caso es proporcionar una base objetiva para el manejo terapéutico de los QQOs en pacientes con SGG y una revisión de la literatura científica. Se presenta el caso de una paciente de 63 años, con antecedentes de SGG, sometida a múltiples intervenciones quirúrgicas, incluida exéresis de QQOs en ambos maxilares, que acudió a la consulta nueve años después de su última intervención para un control por la especialidad, donde se evidenció recurrencia de la lesión en maxilar superior derecho, realizándose enucleación, ostectomia periférica y aplicación de solución de Carnoy.

SUMMARY Gorlin-Goltz syndrome (GGS) is an autosomal dominant disorder characterized by skeletal abnormalities, multi-ple Keratocysts Odontogenic (KCOs) and basal cell carcinoma. Comparative studies of the associated KCOs and those not associated with the GGS have been performed, and the presence of a greater number of satellite cysts, solid proliferations of the epithelium, inflammations, calcifications, more intense mitotic activity of the epithelial cells, and greater recurrence of the KCOs associated with the GGS. The purpose of this case report is to provide an objective basis for the therapeutic management of KCOs in patients with GGS and a review of the scientifi c literature. We present the case of a 63-year-old patient, with a history of GGS, who underwent multiple surgical interventions, including exeresis of KCOs in both jaws, who came to the consultation, nine years after her last intervention, for an Odontostomatological check-up, finding KCO recurrent in upper right maxilla, performing enucleation, peripheral ostectomy and application of carnoy solution.