A role for mutations in AK9 and other genes affecting ependymal cells in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is an enigmatic neurological disorder that develops after age 60 and is characterized by gait difficulty, dementia, and incontinence. Recently, we reported that heterozygous CWH43 deletions may cause iNPH. Here, we identify mutations affecting nine additional genes (AK9, RXFP2, PRKD1, HAVCR1, OTOG, MYO7A, NOTCH1, SPG11, and MYH13) that are statistically enriched among iNPH patients. The encoded proteins are all highly expressed in choroid plexus and ependymal cells, and most have been associated with cilia. Damaging mutations in AK9, which encodes an adenylate kinase, were detected in 9.6% of iNPH patients. Mice homozygous for an iNPH-associated AK9 mutation displayed normal cilia structure and number, but decreased cilia motility and beat frequency, communicating hydrocephalus, and balance impairment. AK9+/- mice displayed normal brain development and behavior until early adulthood, but subsequently developed communicating hydrocephalus. Together, our findings suggest that heterozygous mutations that impair ventricular epithelial function may contribute to iNPH.

OSR1 disruption contributes to uterine factor infertility via impaired Müllerian duct development and endometrial receptivity

Three sisters, born from consanguineous parents, manifested a unique Müllerian anomaly characterized by uterine hypoplasia with thin estrogen-unresponsive endometrium and primary amenorrhea, but with spontaneous tubal pregnancies. Through whole-exome sequencing followed by comprehensive genetic analysis, a missense variant was identified in the OSR1 gene. We therefore investigated OSR1/OSR1 expression in postpubertal human uteri, and the prenatal and postnatal expression pattern of Osr1/Osr1 in murine developing Müllerian ducts (MDs) and endometrium, respectively. We then investigated whether Osr1 deletion would affect MD development, using WT and genetically engineered mice. Human uterine OSR1/OSR1 expression was found primarily in the endometrium. Mouse Osr1 was expressed prenatally in MDs and Wolffian ducts (WDs), from rostral to caudal segments, in E13.5 embryos. MDs and WDs were absent on the left side and MDs were rostrally truncated on the right side of E13.5 Osr1-/- embryos. Postnatally, Osr1 was expressed in mouse uteri throughout their lifespan, peaking at postnatal days 14 and 28. Osr1 protein was present primarily in uterine luminal and glandular epithelial cells and in the epithelial cells of mouse oviducts. Through this translational approach, we demonstrated that OSR1 in humans and mice is important for MD development and endometrial receptivity and may be implicated in uterine factor infertility.

Heterozygous FOXJ1 Mutations Cause Incomplete Ependymal Cell Differentiation and Communicating Hydrocephalus

Heterozygous mutations affecting FOXJ1, a transcription factor governing multiciliated cell development, have been associated with obstructive hydrocephalus in humans. However, factors that disrupt multiciliated ependymal cell function often cause communicating hydrocephalus, raising questions about whether FOXJ1 mutations cause hydrocephalus primarily by blocking cerebrospinal fluid (CSF) flow or by different mechanisms. Here, we show that heterozygous FOXJ1 mutations are also associated with communicating hydrocephalus in humans and cause communicating hydrocephalus in mice. Disruption of one Foxj1 allele in mice leads to incomplete ependymal cell differentiation and communicating hydrocephalus. Mature ependymal cell number and motile cilia number are decreased, and 12% of motile cilia display abnormal axonemes. We observed decreased microtubule attachment to basal bodies, random localization and orientation of basal body patches, loss of planar cell polarity, and a disruption of unidirectional CSF flow. Thus, heterozygous FOXJ1 mutations impair ventricular multiciliated cell differentiation, thereby causing communicating hydrocephalus. CSF flow obstruction may develop secondarily in some patients harboring FOXJ1 mutations. Heterozygous FOXJ1 mutations impair motile cilia structure and basal body alignment, thereby disrupting CSF flow dynamics and causing communicating hydrocephalus.

Familial central precocious puberty due to DLK1 deficiency: novel genetic findings and relevance of serum DLK1 levels

BACKGROUND

Several rare loss-of-function mutations of delta-like noncanonical notch ligand 1 (DLK1) have been described in non-syndromic children with familial central precocious puberty (CPP).

OBJECTIVE

We investigated genetic abnormalities of DLK1 gene in a French cohort of children with idiopathic CPP. Additionally, we explored the pattern of DLK1 serum levels in patients with CPP and in healthy children at puberty, as well as in wild-type female mice.

PATIENTS AND METHODS

Genomic DNA was obtained from 121 French index cases with CPP. Automated sequencing of the coding region of the DLK1 gene was performed in all cases. Serum DLK1 levels were measured by enzyme linked immunosorbent assay (ELISA) in 209 individuals, including 191 with normal pubertal development and in female mice during postnatal pubertal maturation.

RESULTS

We identified 2 rare pathogenic DLK1 allelic variants: A stop gain variant (c.372C>A; p.Cys124X) and a start loss variant (c.2T>G; p.Met1?, or p.0) in 2 French girls with CPP. Mean serum DLK1 levels were similar between healthy children and idiopathic CPP children. In healthy individuals, DLK1 levels correlated with pubertal stage: In girls, DLK1 decreased between Tanner stages III and V, whereas in boys, DLK1 decreased between Tanner stages II and V (P = .008 and .016, respectively). Serum levels of Dlk1 also decreased in wild-type female mice.

CONCLUSIONS

Novel loss-of-function mutations in DLK1 gene were identified in 2 French girls with CPP. Additionally, we demonstrated a pattern of dynamic changes in circulating DLK1 serum levels in humans and mice during pubertal stages, reinforcing the role of this factor in pubertal timing.

Mouse Testicular Mkrn3 Expression Is Primarily Interstitial, Increases Peripubertally, and Is Responsive to LH/hCG

Studies in humans and mice support a role for Makorin RING finger protein 3 (MKRN3) as an inhibitor of gonadotropin-releasing hormone (GnRH) secretion prepubertally, and its loss of function is the most common genetic cause of central precocious puberty in humans. Studies have shown that the gonads can synthesize neuropeptides and express MKRN3/Mkrn3 mRNA. Therefore, we aimed to investigate the spatiotemporal expression pattern of Mkrn3 in gonads during sexual development, and its potential regulation in the functional testicular compartments by gonadotropins. Mkrn3 mRNA was detected in testes and ovaries of wild-type mice at all ages evaluated, with a sexually dimorphic expression pattern between male and female gonads. Mkrn3 expression was highest peripubertally in the testes, whereas it was lower peripubertally than prepubertally in the ovaries. Mkrn3 is expressed primarily in the interstitial compartment of the testes but was also detected at low levels in the seminiferous tubules. In vitro studies demonstrated that Mkrn3 mRNA levels increased in human chorionic gonadotropin (hCG)-treated Leydig cell primary cultures. Acute administration of a GnRH agonist in adult mice increased Mkrn3 expression in testes, whereas inhibition of the hypothalamic-pituitary-gonadal axis by chronic administration of GnRH agonist had the opposite effect. Finally, we found that hCG increased Mkrn3 mRNA levels in a dose-dependent manner. Taken together, our developmental expression analyses, in vitro and in vivo studies show that Mkrn3 is expressed in the testes, predominantly in the interstitial compartment, and that Mkrn3 expression increases after puberty and is responsive to luteinizing hormone/hCG stimulation.

Novel MKRN3 Missense Mutations Associated With Central Precocious Puberty Reveal Distinct Effects on Ubiquitination

CONTEXT

Loss-of-function mutations in the maternally imprinted genes, MKRN3 and DLK1, are associated with central precocious puberty (CPP). Mutations in MKRN3 are the most common known genetic etiology of CPP.

OBJECTIVE

This work aimed to screen patients with CPP for MKRN3 and DLK1 mutations and analyze the effects of identified mutations on protein function in vitro.

METHODS

Participants included 84 unrelated children with CPP (79 girls, 5 boys) and, when available, their first-degree relatives. Five academic medical institutions participated. Sanger sequencing of MKRN3 and DLK1 5' upstream flanking and coding regions was performed on DNA extracted from peripheral blood leukocytes. Western blot analysis was performed to assess protein ubiquitination profiles.

RESULTS

Eight heterozygous MKRN3 mutations were identified in 9 unrelated girls with CPP. Five are novel missense mutations, 2 were previously identified in patients with CPP, and 1 is a frameshift variant not previously associated with CPP. No pathogenic variants were identified in DLK1. Girls with MKRN3 mutations had an earlier age of initial pubertal signs and higher basal serum luteinizing hormone and follicle-stimulating hormone compared to girls with CPP without MRKN3 mutations. Western blot analysis revealed that compared to wild-type MKRN3, mutations within the RING finger domain reduced ubiquitination whereas the mutations outside this domain increased ubiquitination.

CONCLUSION

MKRN3 mutations were present in 10.7% of our CPP cohort, consistent with previous studies. The novel identified mutations in different domains of MKRN3 revealed different patterns of ubiquitination, suggesting distinct molecular mechanisms by which the loss of MRKN3 results in early pubertal onset.

MKRN3 inhibits puberty onset via interaction with IGF2BP1 and regulation of hypothalamic plasticity

Makorin ring finger protein 3 (MKRN3) was identified as an inhibitor of puberty initiation with the report of loss-of-function mutations in association with central precocious puberty. Consistent with this inhibitory role, a prepubertal decrease in Mkrn3 expression was observed in the mouse hypothalamus. Here, we investigated the mechanisms of action of MKRN3 in the central regulation of puberty onset. We showed that MKRN3 deletion in hypothalamic neurons derived from human induced pluripotent stem cells was associated with significant changes in expression of genes controlling hypothalamic development and plasticity. Mkrn3 deletion in a mouse model led to early puberty onset in female mice. We found that Mkrn3 deletion increased the number of dendritic spines in the arcuate nucleus but did not alter the morphology of GnRH neurons during postnatal development. In addition, we identified neurokinin B (NKB) as an Mkrn3 target. Using proteomics, we identified insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) as another target of MKRN3. Interactome analysis revealed that IGF2BP1 interacted with MKRN3, along with several members of the polyadenylate-binding protein family. Our data show that one of the mechanisms by which MKRN3 inhibits pubertal initiation is through regulation of prepubertal hypothalamic development and plasticity, as well as through effects on NKB and IGF2BP1.

OR17-1 MKRN3 Inhibits the Reproductive Axis by Interacting With Key Hypothalamic Substrates and Targeting Neurokinin B to Degradation Pathways

Background and Objectives

Human fertility is attained following puberty due to finely orchestrated events driven by hypothalamic release of the excitatory neuropeptide neurokinin B (NKB), which in turn stimulates the release of kisspeptin and then GnRH to activate the downstream pituitary-gonadal axis. Our group has identified that loss-of-function mutations in Makorin Ring Finger Protein 3 (MKRN3) cause central precocious puberty (CPP). Mkrn3 is highly expressed in the hypothalamus of both male and female mice in early postnatal life, then declines prior to the onset of puberty. Mutations in MKRN3 E3 ubiquitin ligase domain, identified in patients with CPP, result in reduced auto-ubiquitination. However, the mechanisms of action of MKRN3 and its targets remain largely unknown. We hypothesized that MKRN3 inhibits the reproductive axis through interactions with hypothalamic substrates, targeting them to degradation pathways.

Methods and Results

Using interactome analysis and candidate approaches in vitro, we identified poly(A) binding protein cytoplasmic 1 and 4 (PABPC1 and 4) and insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) as MKRN3 interactors, consistent with reports from other research groups. Additionally, our proteomic analysis revealed that Igf2bp1 levels are increased in the hypothalamus of Mkrn3 knockout (KO) mice versus wild type animals. Remarkably, we found that MKRN3-IGF2BP1 interaction is mediated by RNA, as their interaction was abrogated by RNase treatment. However, an MKRN3 missense mutation associated with CPP, p.C364F, within the E3 ubiquitin ligase domain, did not affect the RNA mediated interaction. Preliminary data from RNA co-IP, aiming to identify putative RNA targets, suggested that MKRN3 and IGF2BP1 bind to TAC3 mRNA. We further identified an increase in Nkb protein levels in the hypothalamus of Mkrn3 KO mice. We also showed that NKB is a substrate of MKRN3 E3 ubiquitin ligase activity in vitro by demonstrating increased ubiquitination of NKB in cells co-transfected with expression vectors encoding MKRN3 and NKB and treated with proteasome inhibitor. Additionally, MKRN3 overexpression resulted in degradation of NKB protein by western blot analysis, and alteration of NKB intracellular localization by immunofluorescence. These effects were impaired by MKRN3 missense mutations (p.C340G and p.C364F) in the E3 ubiquitin ligase motif, suggesting a pathophysiological mechanism of MKRN3 mutations in CPP.

Conclusions

We identified that MKRN3 interacts with PABPC1, PABPC4 and IGF2BP1 and targets NKB to degradation. We showed that NKB degradation was mediated by the MKRN3 E3 ubiquitin ligase domain, as mutations within this motif abrogated NKB degradation. However, this mutation did not affect MKRN3 RNA-mediated binding to IGF2BP1, highlighting that multiple domains of MKRN3 may contribute to its actions. Here, we propose a mechanism by which MKRN3, interacting with PABPCs and IGF2BP1 and targeting NKB for degradation, may act to inhibit the reproductive axis.

Presentation: Sunday, June 12, 2022 11:00 a.m. - 11:15 a.m.

Hypothalamic Overexpression of Makorin Ring Finger Protein 3 Results in Delayed Puberty in Female Mice

Makorin ring finger protein 3 (MKRN3) is an important neuroendocrine player in the control of pubertal timing and upstream inhibitor of gonadotropin-releasing hormone secretion. In mice, expression of Mkrn3 in the hypothalamic arcuate and anteroventral periventricular nucleus is high early in life and declines before the onset of puberty. Therefore, we aimed to explore if the persistence of hypothalamic Mkrn3 expression peripubertally would result in delayed puberty. Female mice that received neonatal bilateral intracerebroventricular injections of a recombinant adeno-associated virus expressing Mkrn3 had delayed vaginal opening and first estrus compared with animals injected with control virus. Subsequent estrous cycles and fertility were normal. Interestingly, male mice treated similarly did not exhibit delayed puberty onset. Kiss1, Tac2, and Pdyn mRNA levels were increased in the mediobasal hypothalamus in females at postnatal day 28, whereas kisspeptin and neurokinin B protein levels in the arcuate nucleus were decreased, following Mkrn3 overexpression, compared to controls. Cumulatively, these data suggest that Mkrn3 may directly or indirectly target neuropeptides of Kiss1 neurons to degradation pathways. This mouse model suggests that MKRN3 may be a potential contributor to delayed onset of puberty, in addition to its well-established roles in central precocious puberty and the timing of menarche.

Delivering Therapeutics to Glioblastoma: Overcoming Biological Constraints

Glioblastoma multiforme is the most lethal intrinsic brain tumor. Even with the existing treatment regimen of surgery, radiation, and chemotherapy, the median survival time is only 15–23 months. The invasive nature of this tumor makes its complete removal very difficult, leading to a high recurrence rate of over 90%. Drug delivery to glioblastoma is challenging because of the molecular and cellular heterogeneity of the tumor, its infiltrative nature, and the blood–brain barrier. Understanding the critical characteristics that restrict drug delivery to the tumor is necessary to develop platforms for the enhanced delivery of effective treatments. In this review, we address the impact of tumor invasion, the molecular and cellular heterogeneity of the tumor, and the blood–brain barrier on the delivery and distribution of drugs using potential therapeutic delivery options such as convection-enhanced delivery, controlled release systems, nanomaterial systems, peptide-based systems, and focused ultrasound.

Deletion of Gαq/11 or Gαs Proteins in Gonadotropes Differentially Affects Gonadotropin Production and Secretion in Mice

Gonadotropin-releasing hormone (GnRH) regulates gonadal function via its stimulatory effects on gonadotropin production by pituitary gonadotrope cells. GnRH is released from the hypothalamus in pulses and GnRH pulse frequency differentially regulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) synthesis and secretion. The GnRH receptor (GnRHR) is a G protein-coupled receptor that canonically activates Gα q/11-dependent signaling on ligand binding. However, the receptor can also couple to Gα s and in vitro data suggest that toggling between different G proteins may contribute to GnRH pulse frequency decoding. For example, as we show here, knockdown of Gα s impairs GnRH-stimulated FSH synthesis at low- but not high-pulse frequency in a model gonadotrope-derived cell line. We next used a Cre-lox conditional knockout approach to interrogate the relative roles of Gα q/11 and Gα s proteins in gonadotrope function in mice. Gonadotrope-specific Gα q/11 knockouts exhibit hypogonadotropic hypogonadism and infertility, akin to the phenotypes seen in GnRH- or GnRHR-deficient mice. In contrast, under standard conditions, gonadotrope-specific Gα s knockouts produce gonadotropins at normal levels and are fertile. However, the LH surge amplitude is blunted in Gα s knockout females and postgonadectomy increases in FSH and LH are reduced both in males and females. These data suggest that GnRH may signal principally via Gα q/11 to stimulate gonadotropin production, but that Gα s plays important roles in gonadotrope function in vivo when GnRH secretion is enhanced.

Sex-specific pubertal and metabolic regulation of Kiss1 neurons via Nhlh2

Hypothalamic Kiss1 neurons control gonadotropin-releasing hormone release through the secretion of kisspeptin. Kiss1 neurons serve as a nodal center that conveys essential regulatory cues for the attainment and maintenance of reproductive function. Despite this critical role, the mechanisms that control kisspeptin synthesis and release remain largely unknown. Using Drop-Seq data from the arcuate nucleus of adult mice and in situ hybridization, we identified Nescient Helix-Loop-Helix 2 (Nhlh2), a transcription factor of the basic helix-loop-helix family, to be enriched in Kiss1 neurons. JASPAR analysis revealed several binding sites for NHLH2 in the Kiss1 and Tac2 (neurokinin B) 5' regulatory regions. In vitro luciferase assays evidenced a robust stimulatory action of NHLH2 on human KISS1 and TAC3 promoters. The recruitment of NHLH2 to the KISS1 and TAC3 promoters was further confirmed through chromatin immunoprecipitation. In vivo conditional ablation of Nhlh2 from Kiss1 neurons using Kiss1Cre:Nhlh2fl/fl mice induced a male-specific delay in puberty onset, in line with a decrease in arcuate Kiss1 expression. Females retained normal reproductive function albeit with irregular estrous cycles. Further analysis of male Kiss1Cre:Nhlh2fl/fl mice revealed higher susceptibility to metabolic challenges in the release of luteinizing hormone and impaired response to leptin. Overall, in Kiss1 neurons, Nhlh2 contributes to the metabolic regulation of kisspeptin and NKB synthesis and release, with implications for the timing of puberty onset and regulation of fertility in male mice.

Deletions in CWH43 cause idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder that occurs in about 1% of individuals over age 60 and is characterized by enlarged cerebral ventricles, gait difficulty, incontinence, and cognitive decline. The cause and pathophysiology of iNPH are largely unknown. We performed whole exome sequencing of DNA obtained from 53 unrelated iNPH patients. Two recurrent heterozygous loss of function deletions in CWH43 were observed in 15% of iNPH patients and were significantly enriched 6.6‐fold and 2.7‐fold, respectively, when compared to the general population. Cwh43 modifies the lipid anchor of glycosylphosphatidylinositol‐anchored proteins. Mice heterozygous for CWH43 deletion appeared grossly normal but displayed hydrocephalus, gait and balance abnormalities, decreased numbers of ependymal cilia, and decreased localization of glycosylphosphatidylinositol‐anchored proteins to the apical surfaces of choroid plexus and ependymal cells. Our findings provide novel mechanistic insights into the origins of iNPH and demonstrate that it represents a distinct disease entity.

Evidence for increased intraabdominal pressure as a cause of recurrent migration of the distal catheter of a ventriculoperitoneal shunt: illustrative case

BACKGROUND

Placement of a ventriculoperitoneal (VP) shunt is an effective treatment for several disorders of cerebrospinal fluid flow. A rare complication involves postoperative migration of the distal catheter out of the intraperitoneal compartment and into the subcutaneous space. Several theories attempt to explain this phenomenon, but the mechanism remains unclear.

OBSERVATIONS

The authors report the case of a 37-year-old nonobese woman who underwent placement of a VP shunt for idiopathic intracranial hypertension. Postoperatively, the distal catheter of the VP shunt migrated into the subcutaneous space on three occasions despite the use of multiple surgical techniques, including open and laparoscopic methods of abdominal catheter placement. Notably, the patient repeatedly displayed radiographic evidence of chronic bowel distention consistent with increased intraperitoneal pressure.

LESSONS

In this case, the mechanism of catheter migration into the subcutaneous space did not appear to be caused by pulling of the catheter from above but rather by expulsion of the catheter from the peritoneum. Space in the subcutaneous tissues caused by open surgical placement of the catheter was permissive for this process. Patients with chronic increased intraabdominal pressure, such as that caused by bowel distention, obesity, or Valsalva maneuvers, may be at increased risk for distal catheter migration.

MKRN3 inhibits the reproductive axis through actions in kisspeptin-expressing neurons

The identification of loss-of-function mutations in MKRN3 in patients with central precocious puberty in association with the decrease in MKRN3 expression in the medial basal hypothalamus of mice before the initiation of reproductive maturation suggests that MKRN3 is acting as a brake on gonadotropin-releasing hormone (GnRH) secretion during childhood. In the current study, we investigated the mechanism by which MKRN3 prevents premature manifestation of the pubertal process. We showed that, as in mice, MKRN3 expression is high in the hypothalamus of rats and nonhuman primates early in life, decreases as puberty approaches, and is independent of sex steroid hormones. We demonstrated that Mkrn3 is expressed in Kiss1 neurons of the mouse hypothalamic arcuate nucleus and that MKRN3 repressed promoter activity of human KISS1 and TAC3, 2 key stimulators of GnRH secretion. We further showed that MKRN3 has ubiquitinase activity, that this activity is reduced by MKRN3 mutations affecting the RING finger domain, and that these mutations compromised the ability of MKRN3 to repress KISS1 and TAC3 promoter activity. These results indicate that MKRN3 acts to prevent puberty initiation, at least in part, by repressing KISS1 and TAC3 transcription and that this action may involve an MKRN3-directed ubiquitination-mediated mechanism.

The Peripubertal Decline in Makorin Ring Finger Protein 3 Expression is Independent of Leptin Action

A critical body weight is necessary for pubertal development, an effect mediated in part by leptin. The potential regulation by leptin of Makorin Ring Finger Protein 3 (MKRN3), in which loss-of-function mutations are the most common genetic cause of central precocious puberty, has not been previously explored. In mice, expression of Mkrn3 in the hypothalamic arcuate nucleus is high early in life and declines before the onset of puberty. Therefore, we aimed to explore if leptin contributes to the decrease in hypothalamic Mkrn3 mRNA levels observed in mice during pubertal development. We first used a leptin-deficient (ob/ob) mouse model. Mkrn3 mRNA levels in the mediobasal hypothalamus (MBH), which includes the arcuate nucleus, and in the preoptic area (POA), both showed a significant decrease with age from postnatal day (PND) 12 to PND30 in ob/ob mice in both males and females, similar to that observed in wild-type mice. To further explore the effects of leptin on Mkrn3 expression, we exposed prepubertal wild-type mice to high levels of leptin from age PND9-12, which did not result in any significant difference in Mkrn3 expression levels in either the MBH or POA. In summary, regulation of Mkrn3 expression by leptin was not observed in either the MBH or the POA, 2 hypothalamic sites important for pubertal maturation. These data suggest that the decline in Mkrn3 at the onset of puberty may occur independently of leptin and support our hypothesis that MKRN3 is a bona fide controller of puberty initiation.

SAT-LB57 The Spectrum of Genomic and Transcriptomic Alterations in ACTH-Producing and ACTH-Silent Corticotroph Adenomas

Corticotroph adenomas (CA) are rare pituitary tumors that impose several challenges in clinical management - CA are difficult to diagnose, often recur, and are associated with high morbidity and mortality. CA are characteristically Tpit-positive and PIT1-negative and comprise ACTH-producing (Cushing’s disease (CD)) and ACTH-silent (AS) classes. The molecular programs contributing to disease pathogenesis in CA are still poorly characterized, largely restricted to the identification of somatic mutations in USP8 in 40-60% of CD adenomas. To more fully characterize the mutational and transcriptional landscape driving both classes of CA, we performed whole-exome sequencing and RNA-seq in 19 CD and 16 AS adenomas. We identified USP8 mutations in 53% of CD (10/19) and 6% of AS (1/16) samples. Strikingly, in 19% of AS tumors (3/16), all exhibiting an unusually aggressive disease course, including two cases with brain metastases, we identified recurrent somatic pathogenic mutations in TP53 and novel loss-of-function mutations in telomere maintenance genes DAXX and ATRX. Furthermore, while all tumors with USP8 mutations (regardless of CD/AS status) exhibited no chromosomal abnormalities as measured by copy-number variation (CNV) and loss of heterozygosity (LOH) analysis, 33% of CD (4/12, including 1 tumor with a DAXX mutation) and 36% of AS (4/11, including all DAXX/ATRX-mutated cases) samples exhibited profound chromosomal instability, characterized by hyperdiploidy, widespread whole-chromosome LOH events, and arm-level breakpoints. Using transcriptome analysis (n=22), we identified three classes of tumors (C1-C3), reflecting these distinct somatic alteration profiles. C1 tumors (n=6) are characterized by chromosomal stability, includes exclusively USP8-mutated CD, and exhibits upregulation of genes involved in metabolic processes and protein acetylation. C2 tumors (n=10) are comprised exclusively of AS (including all TP53- and/or DAXX/ATRX-mutated cases), are characterized by chromosomal instability, and exhibits concordant upregulation of cell cycle programs. Finally, C3 (n=6) contains a mixture of AS and CD cases (including CD without mutations in USP8) and features an expression profile that partly overlap with C1 tumors, but also exhibit higher expression of inflammatory genes. Taken together, our data suggest that CD and AS are distinct molecular subtypes of CA, highlighting the dominant role of USP8 mutations in driving a unique transcriptional program and illustrate for the first time that unlike most cases of CD, AS cases are characterized by profound genomic instability and cell cycle activation, features associated with a more aggressive disease course.

MKRN3 Mutations in Central Precocious Puberty: A Systematic Review and Meta-Analysis

MKRN3 mutations represent the most common genetic cause of central precocious puberty (CPP) but associations between genotype and clinical features have not been extensively explored. This systematic review and meta-analysis investigated genotype-phenotype associations and prevalence of MKRN3 mutations in CPP. The search was conducted in seven electronic databases (Cochrane, EMBASE, LILACS, LIVIVO, PubMed, Scopus, and Web of Science) for articles published until 4 September 2018. Studies evaluating MKRN3 mutations in patients with CPP were considered eligible. A total of 22 studies, studying 880 subjects with CPP, fulfilled the inclusion criteria. Eighty-nine subjects (76 girls) were identified as harboring MKRN3 mutations. Girls, compared with boys, exhibited earlier age at pubertal onset (median, 6.0 years; range, 3.0 to 7.0 vs 8.5 years; range, 5.9 to 9.0; P < 0.001), and higher basal FSH levels (median, 4.3 IU/L; range, 0.7 to 13.94 IU/L vs 2.45 IU/L; range, 0.8 to 13.70 IU/L; P = 0.003), and bone age advancement (ΔBA; median, 2.3 years; range, -0.9 to 5.2 vs 1.2 years; range, 0.0 to 2.3; P = 0.01). Additional dysmorphisms were uncommon. A total of 14 studies evaluating 857 patients were included for quantitative analysis, with a pooled overall mutation prevalence of 9.0% (95% CI, 0.04 to 0.15). Subgroup analysis showed that prevalence estimates were higher in males, familial cases, and in non-Asian countries. In conclusion, MKRN3 mutations are associated with nonsyndromic CPP and manifest in a sex-dimorphic manner, with girls being affected earlier. They represent a common cause of CPP in western countries, especially in boys and familial cases.

MicroRNA-29a activates a multi-component growth and invasion program in glioblastoma

Background

Glioblastoma is a malignant brain tumor characterized by rapid growth, diffuse invasion and therapeutic resistance. We recently used microRNA expression profiles to subclassify glioblastoma into five genetically and clinically distinct subclasses, and showed that microRNAs both define and contribute to the phenotypes of these subclasses. Here we show that miR-29a activates a multi-faceted growth and invasion program that promotes glioblastoma aggressiveness.

Methods

microRNA expression profiles from 197 glioblastomas were analyzed to identify the candidate miRNAs that are correlated to glioblastoma aggressiveness. The candidate miRNA, miR-29a, was further studied in vitro and in vivo.

Results

Members of the miR-29 subfamily display increased expression in the two glioblastoma subclasses with the worst prognoses (astrocytic and neural). We observed that miR-29a is among the microRNAs that are most positively-correlated with PTEN copy number in glioblastoma, and that miR-29a promotes glioblastoma growth and invasion in part by targeting PTEN. In PTEN-deficient glioblastoma cells, however, miR-29a nevertheless activates AKT by downregulating the metastasis suppressor, EphB3. In addition, miR-29a robustly promotes invasion in PTEN-deficient glioblastoma cells by repressing translation of the Sox4 transcription factor, and this upregulates the invasion-promoting protein, HIC5. Indeed, we identified Sox4 as the most anti-correlated predicted target of miR-29a in glioblastoma. Importantly, inhibition of endogenous miR-29a decreases glioblastoma growth and invasion in vitro and in vivo, and increased miR-29a expression in glioblastoma specimens correlates with decreased patient survival.

Conclusions

Taken together, these data identify miR-29a as a master regulator of glioblastoma growth and invasion.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1026-1) contains supplementary material, which is available to authorized users.

GnRH-A Key Regulator of FSH

The hypothalamic decapeptide, GnRH, is the gatekeeper of mammalian reproductive development and function. Activation of specific, high-affinity cell surface receptors (GnRH receptors) on gonadotropes by GnRH triggers signal transduction cascades to stimulate the coordinated synthesis and secretion of the pituitary gonadotropins FSH and LH. These hormones direct gonadal steroidogenesis and gametogenesis, making their tightly regulated production and secretion essential for normal sexual maturation and reproductive health. FSH and LH are glycoprotein heterodimers comprised of a common α-subunit and a unique β-subunit (FSHβ and LHβ, respectively), which determines the biological specificity of the gonadotropins. The unique β-subunit is the rate-limiting step for the production of the mature gonadotropins. Therefore, FSH synthesis is regulated at the transcriptional level by Fshb gene expression. The overarching goal of this review is to expand our understanding of the mechanisms and pathways underlying the carefully orchestrated control of FSH synthesis and secretion by GnRH, focusing on the transcriptional regulation of the Fshb gene. Identification of these regulatory mechanisms is not only fundamental to our understanding of normal reproductive function but will also provide a context for the elucidation of the pathophysiology of reproductive disorders and infertility to lead to potential new therapeutic approaches.

S-Nitrosoglutathione Reductase (GSNOR) Deficiency Results in Secondary Hypogonadism

BACKGROUND

Excess reactive oxygen species and reactive nitrogen species are implicated in male infertility and impaired spermatogenesis.

AIM

To investigate the effect of excess reactive nitrogen species and nitrosative stress on testicular function and the hypothalamic-pituitary-gonadal axis using the S-nitrosoglutathione reductase-null (Gsnor^-/-) mouse model.

METHODS

Testis size, pup number, and epididymal sperm concentration and motility of Gsnor^-/- mice were compared with those of age-matched wild-type (WT) mice. Reproductive hormones testosterone (T), luteinizing hormone (LH), and follicle-stimulating hormone were compared in Gsnor^-/- and WT mice. Immunofluorescence for Gsnor^-/- and WT testis was performed for 3β-hydroxysteroid dehydrogenase and luteinizing hormone receptor (LHR) and compared. Human chorionic gonadotropin and gonadotropin-releasing hormone stimulation tests were performed to assess and compare testicular and pituitary functions of Gsnor^-/- and WT mice.

OUTCOMES

Evaluation of fertility and reproductive hormones in Gsnor^-/- vs WT mice. Response of Gsnor^-/- and WT mice to human chorionic gonadotropin and gonadotropin-releasing hormone to evaluate LH and T production.

RESULTS

Gsnor^-/- mice had smaller litters (4.2 vs 8.0 pups per litter; P < .01), smaller testes (0.08 vs 0.09 g; P < .01), and decreased epididymal sperm concentration (69 vs 98 × 10⁶; P < .05) and motility (39% vs 65%; P < .05) compared with WT mice. Serum T (44.8 vs 292.2 ng/dL; P < .05) and LH (0.03 vs 0.74 ng/mL; P = .04) were lower in Gsnor^-/- than in WT mice despite similar follicle-stimulating hormone levels (63.98 vs 77.93 ng/mL; P = .20). Immunofluorescence of Gsnor^-/- and WT testes showed similar staining of 3β-hydroxysteroid dehydrogenase and LHR. Human chorionic gonadotropin stimulation of Gsnor^-/- mice increased serum T (>1,680 vs >1,680 ng/dL) and gonadotropin-releasing hormone stimulation increased serum LH (6.3 vs 8.9 ng/mL; P = .20) similar to WT mice.

CLINICAL TRANSLATION

These findings provide novel insight to a possible mechanism of secondary hypogonadism from increased reactive nitrogen species and excess nitrosative stress.

STRENGTHS AND LIMITATIONS

Limitations of this study are its small samples and variability in hormone levels.

CONCLUSION

Deficiency of S-nitrosoglutathione reductase results in secondary hypogonadism, suggesting that excess nitrosative stress can affect LH production from the pituitary gland. Masterson TA, Arora H, Kulandavelu S, et al. S-Nitrosoglutathione Reductase (GSNOR) Deficiency Results in Secondary Hypogonadism. J Sex Med 2018;15:654-661.

Characterization of Thyroid Disorders in Patients Receiving Immune Checkpoint Inhibition Therapy

Thyroid disorders have emerged as one of the most common immune-related adverse events associated with anti-PD-1 monotherapy or combination anti-PD-1 and anti-CTLA-4 therapy. This study characterizes and compares the evolution of monotherapy and combination therapy-related thyroid disorders. We analyzed the dynamic evolution of thyroid disorders in 45 patients who developed thyroid disorders following treatment with either anti-PD-1 monotherapy or anti-PD-1 and anti-CTLA-4 combination therapy. The patients presented with thyrotoxicosis or hypothyroidism as the initial presentation of their thyroid disorder. Thyrotoxicosis as the initial presentation occurred in the majority of patients (93% and 56% of the patients receiving combination therapy and monotherapy, respectively). The onset pattern of the thyroid disorder was significantly different between the two groups (P = 0.01). Subsequently, 76% and 90% of the patients with thyrotoxicosis evolved to develop hypothyroidism in the combination and monotherapy groups, respectively. In the combination therapy and monotherapy groups, the median times to onset of thyrotoxicosis and hypothyroidism after first treatment were 21 and 63 days, and 31 and 68 days, respectively. The median time for transition from thyrotoxicosis to hypothyroidism was 42 days in both groups. Our study demonstrates that most thyroid disorders induced by either anti-PD-1 or combination anti-PD-1 and anti-CTLA-4 therapy are thyroiditis. The time to onset of thyrotoxicosis after treatment initiation and evolution of thyrotoxicosis to hypothyroidism was short, emphasizing the importance of close monitoring of thyroid function in these patients. Cancer Immunol Res; 5(12); 1133-40. ©2017 AACR.

Tac1 Signaling Is Required for Sexual Maturation and Responsiveness of GnRH Neurons to Kisspeptin in the Male Mouse

The tachykinins substance P (SP) and neurokinin A (Tac1) have emerged as novel regulators of kisspeptin/GnRH release. Recently, we documented that SP modulates reproductive function in the female mouse. Here, we extended this characterization to the male mouse. Tac1-/- male mice showed delayed puberty onset. They also presented significantly decreased expression levels of Pdyn (dynorphin) and Nos1 (nitric oxide synthase) in the mediobasal hypothalamus and elevated Gnrh1 levels. Unexpectedly, the response of Tac1-/- mice to central kisspeptin or senktide (neurokinin B receptor-agonist) administration was significantly decreased compared with controls, despite the preserved ability of GnRH neurons to stimulate luteinizing hormone release as demonstrated by central N-methyl-D-aspartate receptor administration, suggesting a deficit at the GnRH neuron level. Importantly, we demonstrated that kisspeptin receptor and SP receptor (NK1R) heterodimerize, indicating that changes in the SP tone could alter the responsiveness of GnRH neurons to kisspeptin. Finally, electrophysiological recordings from arcuate Kiss1 neurons showed that, although virtually all Kiss1 neurons responded to NKB and senktide, only half responded to an NK1R agonist and none to the neurokinin A receptor agonist at a 1-μM dose. In summary, we provide compelling evidence for a role of Tac1 in the control of reproductive function in the male mouse, suggesting a predominant central action that may involve a change in the balance of neural factors that control GnRH expression.

Paternally Inherited DLK1 Deletion Associated With Familial Central Precocious Puberty

CONTEXT

Central precocious puberty (CPP) results from premature activation of the hypothalamic-pituitary-gonadal axis. Few genetic causes of CPP have been identified, with the most common being mutations in the paternally expressed imprinted gene MKRN3.

OBJECTIVE

To identify the genetic etiology of CPP in a large multigenerational family.

DESIGN

Linkage analysis followed by whole-genome sequencing was performed in a family with five female members with nonsyndromic CPP. Detailed phenotyping was performed at the time of initial diagnosis and long-term follow-up, and circulating levels of Delta-like 1 homolog (DLK1) were measured in affected individuals. Expression of DLK1 was measured in mouse hypothalamus and in kisspeptin-secreting neuronal cell lines in vitro.

SETTING

Endocrine clinic of an academic medical center.

PATIENTS

Patients with familial CPP were studied.

RESULTS

A complex defect of DLK1 (∼14-kb deletion and 269-bp duplication) was identified in this family. This deletion included the 5' untranslated region and the first exon of DLK1, including the translational start site. Only family members who inherited the defect from their father have precocious puberty, consistent with the known imprinting of DLK1. The patients did not demonstrate additional features of the imprinted disorder Temple syndrome except for increased fat mass. Serum DLK1 levels were undetectable in all affected individuals. Dlk1 was expressed in mouse hypothalamus and in kisspeptin neuron-derived cell lines.

CONCLUSION

We identified a genomic defect in DLK1 associated with isolated familial CPP. MKRN3 and DLK1 are both paternally expressed imprinted genes. These findings suggest a role of genomic imprinting in regulating the timing of human puberty.

Association between shunt-responsive idiopathic normal pressure hydrocephalus and alcohol

OBJECTIVE Idiopathic normal pressure hydrocephalus (iNPH) is characterized by ventriculomegaly, gait difficulty, incontinence, and dementia. The symptoms can be ameliorated by CSF drainage. The object of this study was to identify factors associated with shunt-responsive iNPH. METHODS The authors reviewed the medical records of 529 patients who underwent shunt placement for iNPH at their institution between July 2001 and March 2015. Variables associated with shunt-responsive iNPH were identified using bivariate and multivariate analyses. Detailed alcohol consumption information was obtained for 328 patients and was used to examine the relationship between alcohol and shunt-responsive iNPH. A computerized patient registry from 2 academic medical centers was queried to determine the prevalence of alcohol abuse among 1665 iNPH patients. RESULTS Bivariate analysis identified associations between shunt-responsive iNPH and gait difficulty (OR 4.59, 95% CI 2.32-9.09; p < 0.0001), dementia (OR 1.79, 95% CI 1.14-2.80; p = 0.01), incontinence (OR 1.77, 95% CI 1.13-2.76; p = 0.01), and alcohol use (OR 1.98, 95% CI 1.23-3.16; p = 0.03). Borderline significance was observed for hyperlipidemia (OR 1.56, 95% CI 0.99-2.45; p = 0.054), a family history of hyperlipidemia (OR 3.09, 95% CI 0.93-10.26, p = 0.054), and diabetes (OR 1.83, 95% CI 0.96-3.51; p = 0.064). Multivariate analysis identified associations with gait difficulty (OR 3.98, 95% CI 1.81-8.77; p = 0.0006) and alcohol (OR 1.94, 95% CI 1.10-3.39; p = 0.04). Increased alcohol intake correlated with greater improvement after CSF drainage. Alcohol abuse was 2.5 times more prevalent among iNPH patients than matched controls. CONCLUSIONS Alcohol consumption is associated with the development of shunt-responsive iNPH.

GnRH Pulse Frequency Control of Fshb Gene Expression Is Mediated via ERK1/2 Regulation of ICER

The pulsatile release of GnRH regulates the synthesis and secretion of pituitary FSH and LH. Two transcription factors, cAMP-response element-binding protein (CREB) and inducible cAMP early repressor (ICER), have been implicated in the regulation of rat Fshb gene expression. We previously showed that the protein kinase A pathway mediates GnRH-stimulated CREB activation. We hypothesized that CREB and ICER are activated by distinct signaling pathways in response to pulsatile GnRH to modulate Fshb gene expression, which is preferentially stimulated at low vs high pulse frequencies. In the LβT2 gonadotrope-derived cell line, GnRH stimulation increased ICER mRNA and protein. Blockade of ERK activation with mitogen-activated protein kinase kinase I/II (MEKI/II) inhibitors significantly attenuated GnRH induction of ICER mRNA and protein, whereas protein kinase C, calcium/calmodulin-dependent protein kinase II, and protein kinase A inhibitors had minimal effects. GnRH also stimulated ICER in primary mouse pituitary cultures, attenuated similarly by a MEKI/II inhibitor. In a perifusion paradigm, MEKI/II inhibition in LβT2 cells stimulated with pulsatile GnRH abrogated ICER induction at high GnRH pulse frequencies, with minimal effect at low frequencies. MEKI/II inhibition reduced GnRH stimulation of Fshb at high and low pulse frequencies, suggesting that the ERK pathway has additional effects on GnRH regulation of Fshb, beyond those mediated by ICER. Indeed, induction of the activating protein 1 proteins, cFos and cJun, positive modulators of Fshb transcription, by pulsatile GnRH was also abrogated by inhibition of the MEK/ERK signaling pathway. Collectively, these studies indicate that the signaling pathways mediating GnRH activation of CREB and ICER are distinct, contributing to the decoding of the pulsatile GnRH to regulate FSHβ expression.

Computational Analysis of Missense Variants of G Protein-Coupled Receptors Involved in the Neuroendocrine Regulation of Reproduction

INTRODUCTION

Many missense variants in G protein-coupled receptors (GPCRs) involved in the neuroendocrine regulation of reproduction have been identified by phenotype-driven or large-scale exome sequencing. Computational functional prediction analysis is commonly performed to evaluate their impact on receptor function.

METHODS

To assess the performance and outcome of functional prediction analyses for these GPCRs, we performed a statistical analysis of the prediction performance of SIFT and PolyPhen-2 for variants with documented biological function as well as variants retrieved from Ensembl. We obtained missense variants with documented biological function testing from patients with reproductive disorders from a comprehensive literature search. Missense variants from individuals with known reproductive disorders were retrieved from the Human Gene Mutation Database. Missense variants from the general population were retrieved from the Ensembl genome database.

RESULTS

The accuracies of SIFT and PolyPhen-2 were 83 and 85%, respectively. The performance of both prediction tools was greater in predicting loss-of-function variants (SIFT: 92%; PolyPhen-2: 95%) than in predicting variants that did not affect function (SIFT: 54%; PolyPhen-2: 57%). Concordance between SIFT and PolyPhen-2 did not improve accuracy. Surprisingly, approximately half of the variants retrieved from Ensembl were predicted as loss-of-function variants by SIFT (47%) and PolyPhen-2 (54%).

CONCLUSION

Our findings provide new guidance for interpreting the results and limitations of computational functional prediction analyses for GPCRs and will help to determine which variants require biological function testing. In addition, our findings raise important questions regarding the link between genotype and phenotype in the general population.

RF9 Acts as a KISS1R Agonist In Vivo and In Vitro

RF9, a reported antagonist of the mammalian gonadotropin-inhibitory hormone receptor, stimulates gonadotropin secretion in mammals. Recent studies have suggested that the stimulatory effect of RF9 on gonadotropin secretion relies on intact kisspeptin receptor (KISS1R) signaling, but the underlying mechanisms remain to be elucidated. Using Chinese Hamster Ovary cells stably transfected with KISS1R, we show that RF9 binds specifically to KISS1R, with a Kd of 1.6 × 10(-5)M, and stimulates an increase in intracellular calcium and inositol phosphate accumulation in a KISS1R-dependent manner, with EC50 values of 3.0 × 10(-6)M and 1.6 × 10(-7)M, respectively. RF9 also stimulated ERK phosphorylation, with a time course similar to that of kisspeptin-10. RFRP-3, the putative endogenous ligand for NPFFR1, did not stimulate inositol phosphate accumulation or pERK, nor did it alter responses to of kisspeptin-10 or RF9. In agreement with these in vitro data, we found that RF9 stimulated a robust LH increase in Npffr1(-/-) mice, similar to that in wild-type littermates, whereas the stimulatory effect of RF9 was markedly reduced in Kiss1r(-/-) and double Kiss1r(-/-)/Npfrr1(-/-) mice. The stimulatory effect of RF9 on LH secretion was restored by the selective rescue of Kiss1r expression in GnRH neurons, in Kiss1r(-/-T) mice. Taken together, our study demonstrates that RF9 acts primarily as a KISS1R agonist, but not as an allosteric modulator, to stimulate LH secretion. Our findings raise questions regarding the utility of RF9 for assessing NPFF1R function and de-emphasize a predominant role of this signaling system in central regulation of reproduction.

Substance p regulates puberty onset and fertility in the female mouse

Puberty is a tightly regulated process that leads to reproductive capacity. Kiss1 neurons are crucial in this process by stimulating GnRH, yet how Kiss1 neurons are regulated remains unknown. Substance P (SP), an important neuropeptide in pain perception, induces gonadotropin release in adult mice in a kisspeptin-dependent manner. Here, we assessed whether SP, through binding to its receptor NK1R (neurokinin 1 receptor), participates in the timing of puberty onset and fertility in the mouse. We observed that 1) selective NK1R agonists induce gonadotropin release in prepubertal females; 2) the expression of Tac1 (encoding SP) and Tacr1 (NK1R) in the arcuate nucleus is maximal before puberty, suggesting increased SP tone; 3) repeated exposure to NK1R agonists prepubertally advances puberty onset; and 4) female Tac1(-/-) mice display delayed puberty; moreover, 5) SP deficiency leads to subfertility in females, showing fewer corpora lutea and antral follicles and leading to decreased litter size. Thus, our findings support a role for SP in the stimulation of gonadotropins before puberty, acting via Kiss1 neurons to stimulate GnRH release, and its involvement in the attainment of full reproductive capabilities in female mice.

The integrated hypothalamic tachykinin-kisspeptin system as a central coordinator for reproduction

Tachykinins are comprised of the family of related peptides, substance P (SP), neurokinin A (NKA), and neurokinin B (NKB). NKB has emerged as regulator of kisspeptin release in the arcuate nucleus (ARC), whereas the roles of SP and NKA in reproduction remain unknown. This work explores the roles of SP and NKA in the central regulation of GnRH release. First, central infusion of specific agonists for the receptors of SP (neurokinin receptor 1, NK1R), NKA (NK2R) and NKB (NK3R) each induced gonadotropin release in adult male and ovariectomized, estradiol-replaced female mice, which was absent in Kiss1r(-/-) mice, indicating a kisspeptin-dependent action. The NK2R agonist, however, decreased LH release in ovariectomized-sham replaced females, as documented for NK3R agonists but in contrast to the NK1R agonist, which further increased LH release. Second, Tac1 (encoding SP and NKA) expression in the ARC and ventromedial nucleus was inhibited by circulating estradiol but did not colocalize with Kiss1 mRNA. Third, about half of isolated ARC Kiss1 neurons expressed Tacr1 (NK1R) and 100% Tacr3 (NK3R); for anteroventral-periventricular Kiss1 neurons and GnRH neurons, approximately one-fourth expressed Tacr1 and one-tenth Tacr3; Tacr2 (NK2R) expression was absent in all cases. Overall, these results identify a potent regulation of gonadotropin release by the SP/NK1R and NKA/NK2R systems in the presence of kisspeptin-Kiss1r signaling, indicating that they may, along with NKB/NK3R, control GnRH release, at least in part through actions on Kiss1 neurons.

Systemic high-dose corticosteroid treatment does not improve the outcome of ipilimumab-related hypophysitis: a retrospective cohort study

PURPOSE

To examine the onset and outcome of ipilimumab-related hypophysitis and the response to treatment with systemic high-dose corticosteroids (HDS).

EXPERIMENTAL DESIGN

Twenty-five patients who developed ipilimumab-related hypophysitis were analyzed for the incidence, time to onset, time to resolution, frequency of resolution, and the effect of systemic HDS on clinical outcome. To calculate the incidence, the total number (187) of patients with metastatic melanoma treated with ipilimumab at Dana-Farber Cancer Institute (DFCI; Boston, MA) was retrieved from the DFCI oncology database. Comparisons between corticosteroid treatment groups were performed using the Fisher exact test. The distributions of overall survival were based on the method of Kaplan-Meier.

RESULTS

The overall incidence of ipilimumab-related hypophysitis was 13%, with a higher rate in males (16.1%) than females (8.7%). The median time to onset of hypophysitis after initiation of ipilimumab treatment was 9 weeks (range, 5-36 weeks). Resolution of pituitary enlargement, secondary adrenal insufficiency, secondary hypothyroidism, male secondary hypogonadism, and hyponatremia occurred in 73%, 0%, 64%, 45%, and 92% of patients, respectively. Systemic HDS treatment did not improve the outcome of hypophysitis as measured by resolution frequency and time to resolution. One-year overall survival in the cohort of patients was 83%, and while it was slightly higher in patients who did not receive HDS, there was no statistically significant difference between treatment arms.

CONCLUSION

Systemic HDS therapy in patients with ipilimumab-related hypophysitis may not be indicated. Instead, supportive treatment of hypophysitis-related hormone deficiencies with the corresponding hormone replacement should be given.

KISS1R signals independently of Gαq/11 and triggers LH secretion via the β-arrestin pathway in the male mouse

Hypothalamic GnRH is the master regulator of the neuroendocrine reproductive axis, and its secretion is regulated by many factors. Among these is kisspeptin (Kp), a potent trigger of GnRH secretion. Kp signals via the Kp receptor (KISS1R), a Gαq/11-coupled 7-transmembrane-spanning receptor. Until this study, it was understood that KISS1R mediates GnRH secretion via the Gαq/11-coupled pathway in an ERK1/2-dependent manner. We recently demonstrated that KISS1R also signals independently of Gαq/11 via β-arrestin and that this pathway also mediates ERK1/2 activation. Because GnRH secretion is ERK1/2-dependent, we hypothesized that KISS1R regulates GnRH secretion via both the Gαq/11- and β-arrestin-coupled pathways. To test this hypothesis, we measured LH secretion, a surrogate marker of GnRH secretion, in mice lacking either β-arrestin-1 or β-arrestin-2. Results revealed that Kp-dependent LH secretion was significantly diminished relative to wild-type mice (P < .001), thus supporting that β-arrestin mediates Kp-induced GnRH secretion. Based on this, we hypothesized that Gαq/11-uncoupled KISS1R mutants, like L148S, will display Gαq/11-independent signaling. To test this hypothesis, L148S was expressed in HEK 293 cells. and results confirmed that, although strongly uncoupled from Gαq/11, L148S retained the ability to trigger significant Kp-dependent ERK1/2 phosphorylation (P < .05). Furthermore, using mouse embryonic fibroblasts lacking β-arrestin-1 and -2, we demonstrated that L148S-mediated ERK1/2 phosphorylation is β-arrestin-dependent. Overall, we conclude that KISS1R signals via Gαq/11 and β-arrestin to regulate GnRH secretion. This novel and important finding could explain why patients bearing some types of Gαq/11-uncoupled KISS1R mutants display partial gonadotropic deficiency and even a reversal of the condition, idiopathic hypogonadotropic hypogonadism.

Role of gonadotropin-releasing hormone receptor mutations in patients with a wide spectrum of pubertal delay

OBJECTIVE

To analyze the GNRHR in patients with normosmic isolated hypogonadotropic hypogonadism (IHH) and constitutional delay of growth and puberty (CDGP).

DESIGN

Molecular analysis and in vitro experiments correlated with phenotype.

SETTING

Academic medical center.

PATIENT(S)

A total of 110 individuals with normosmic IHH (74 male patients) and 50 with CDGP.

INTERVENTION(S)

GNRHR coding region was amplified and sequenced.

MAIN OUTCOME MEASURE(S)

Novel variants were submitted to in vitro analysis. Frequency of mutations and genotype-phenotype correlation were analyzed. Microsatellite markers flanking GNRHR were examined in patients carrying the same mutation to investigate a possible founder effect.

RESULT(S)

Eleven IHH patients (10%) carried biallelic GNRHR mutations. In vitro analysis of novel variants (p.Y283H and p.V134G) demonstrated complete inactivation. The founder effect study revealed that Brazilian patients carrying the p.R139H mutation shared the same haplotype. Phenotypic spectrum in patients with GNRHR mutations varied from complete GnRH deficiency to partial and reversible IHH, with a relatively good genotype-phenotype correlation. One boy with CDGP was heterozygous for the p.Q106R variant, which was not considered to be pathogenic.

CONCLUSION(S)

GNRHR mutations are a frequent cause of congenital normosmic IHH and should be the first candidate gene for genetic screening in this condition, especially in autosomal recessive familial cases. The founder effect study suggested that the p.R139H mutation arises from a common ancestor in the Brazilian population. Finally, mutations in GNRHR do not appear to be involved in the pathogenesis of CDGP.

Central precocious puberty that appears to be sporadic caused by paternally inherited mutations in the imprinted gene makorin ring finger 3

CONTEXT

Loss-of-function mutations in makorin ring finger 3 (MKRN3), an imprinted gene located on the long arm of chromosome 15, have been recognized recently as a cause of familial central precocious puberty (CPP) in humans. MKRN3 has a potential inhibitory effect on GnRH secretion.

OBJECTIVES

The objective of the study was to investigate potential MKRN3 sequence variations as well as copy number and methylation abnormalities of the 15q11 locus in patients with apparently sporadic CPP.

SETTING AND PARTICIPANTS

We studied 215 unrelated children (207 girls and eight boys) from three university medical centers with a diagnosis of CPP. All but two of these patients (213 cases) reported no family history of premature sexual development. First-degree relatives of patients with identified MKRN3 variants were included for genetic analysis.

MAIN OUTCOME MEASURES

All 215 CPP patients were screened for MKRN3 mutations by automatic sequencing. Multiplex ligation-dependent probe amplification was performed in a partially overlapping cohort of 52 patients.

RESULTS

We identified five novel heterozygous mutations in MKRN3 in eight unrelated girls with CPP. Four were frame shift mutations predicted to encode truncated proteins and one was a missense mutation, which was suggested to be deleterious by in silico analysis. All patients with MKRN3 mutations had classical features of CPP with a median age of onset at 6 years. Copy number and methylation abnormalities at the 15q11 locus were not detected in the patients tested for these abnormalities. Segregation analysis was possible in five of the eight girls with MKRN3 mutations; in all cases, the mutation was inherited on the paternal allele.

CONCLUSIONS

We have identified novel inherited MKRN3 defects in children with apparently sporadic CPP, supporting a fundamental role of this peptide in the suppression of the reproductive axis.

KAP regulates ROCK2 and Cdk2 in an RNA-activated glioblastoma invasion pathway

Aberrant splicing of the cyclin-dependent kinase-associated phosphatase, KAP, promotes glioblastoma invasion in a Cdc2-dependent manner. However, the mechanism by which this occurs is unknown. Here we show that miR-26a, which is often amplified in glioblastoma, promotes invasion in phosphatase and tensin homolog (PTEN)-competent and PTEN-deficient glioblastoma cells by directly downregulating KAP expression. Mechanistically, we find that KAP binds and activates ROCK2. Thus, RNA-mediated downregulation of KAP leads to decreased ROCK2 activity and this, in turn, increases Rac1-mediated invasion. In addition, the decrease in KAP expression activates the cyclin-dependent kinase, Cdk2, and this directly promotes invasion by increasing retinoblastoma phosphorylation, E2F-dependent Cdc2 expression and Cdc2-mediated inactivation of the actomyosin inhibitor, caldesmon. Importantly, glioblastoma cell invasion mediated by this pathway can be antagonized by Cdk2/Cdc2 inhibitors in vitro and in vivo. Thus, two distinct RNA-based mechanisms activate this novel KAP/ROCK2/Cdk2-dependent invasion pathway in glioblastoma.

TACR3 mutations disrupt NK3R function through distinct mechanisms in GnRH-deficient patients

Neurokinin B (NKB) and its G-protein-coupled receptor, NK3R, have been implicated in the neuroendocrine control of GnRH release; however, little is known about the structure-function relationship of this ligand-receptor pair. Moreover, loss-of-function NK3R mutations cause GnRH deficiency in humans. Using missense mutations in NK3R we previously identified in patients with GnRH deficiency, we demonstrate that Y256H and Y315C NK3R mutations in the fifth and sixth transmembrane domains (TM5 and TM6), resulted in reduced whole-cell (79.3±7.2%) or plasma membrane (67.3±7.3%) levels, respectively, compared with wild-type (WT) NK3R, with near complete loss of inositol phosphate (IP) signaling, implicating these domains in receptor trafficking, processing, and/or stability. We further demonstrate in a FRET-based assay that R295S NK3R, in the third intracellular loop (IL3), bound NKB but impaired dissociation of Gq-protein subunits from the receptor compared with WT NK3R, which showed a 10.0 ± 1.3% reduction in FRET ratios following ligand binding, indicating activation of Gq-protein signaling. Interestingly, R295S NK3R, identified in the heterozygous state in a GnRH-deficient patient, also interfered with dissociation of G proteins and IP signaling from wild-type NK3R, indicative of dominant-negative effects. Collectively, our data illustrate roles for TM5 and TM6 in NK3R trafficking and ligand binding and for IL3 in NK3R signaling.

Dynamic kisspeptin receptor trafficking modulates kisspeptin-mediated calcium signaling

Kisspeptin receptor (KISS1R) signaling plays a critical role in the regulation of reproduction. We investigated the role of kisspeptin-stimulated KISS1R internalization, recycling, and degradation in the modulation of KISS1R signaling. Kisspeptin stimulation of Chinese hamster ovary or GT1-7 cells expressing KISS1R resulted in a biphasic increase in intracellular Ca(2+) ([Ca(2+)]i), with a rapid acute increase followed by a more sustained second phase. In contrast, stimulation of the TRH receptor, another Gq/11-coupled receptor, resulted in a much smaller second-phase [Ca(2+)]i response. The KISS1R-mediated second-phase [Ca(2+)]i response was abolished by removal of kisspeptin from cell culture medium. Notably, the second-phase [Ca(2+)]i response was also inhibited by dynasore, brefeldin A, and phenylarsine oxide, which inhibit receptor internalization and recycling, suggesting that KISS1R trafficking contributes to the sustained [Ca(2+)]i response. We further demonstrated that KISS1R undergoes dynamic ligand-dependent and -independent recycling. We next investigated the fate of the internalized kisspeptin-KISS1R complex. Most internalized kisspeptin was released extracellularly in degraded form within 1 hour, suggesting rapid processing of the internalized kisspeptin-KISS1R complex. Using a biotinylation assay, we demonstrated that degradation of cell surface KISS1R was much slower than that of the internalized ligand, suggesting dissociated processing of the internalized kisspeptin-KISS1R complex. Taken together, our results suggest that the sustained calcium response to kisspeptin is dependent on the continued presence of extracellular ligand and is the result of dynamic KISS1R trafficking.

Central precocious puberty caused by mutations in the imprinted gene MKRN3

BACKGROUND

The onset of puberty is first detected as an increase in pulsatile secretion of gonadotropin-releasing hormone (GnRH). Early activation of the hypothalamic-pituitary-gonadal axis results in central precocious puberty. The timing of pubertal development is driven in part by genetic factors, but only a few, rare molecular defects associated with central precocious puberty have been identified.

METHODS

We performed whole-exome sequencing in 40 members of 15 families with central precocious puberty. Candidate variants were confirmed with Sanger sequencing. We also performed quantitative real-time polymerase-chain-reaction assays to determine levels of messenger RNA (mRNA) in the hypothalami of mice at different ages.

RESULTS

We identified four novel heterozygous mutations in MKRN3, the gene encoding makorin RING-finger protein 3, in 5 of the 15 families; both sexes were affected. The mutations included three frameshift mutations, predicted to encode truncated proteins, and one missense mutation, predicted to disrupt protein function. MKRN3 is a paternally expressed, imprinted gene located in the Prader-Willi syndrome critical region (chromosome 15q11-q13). All affected persons inherited the mutations from their fathers, a finding that indicates perfect segregation with the mode of inheritance expected for an imprinted gene. Levels of Mkrn3 mRNA were high in the arcuate nucleus of prepubertal mice, decreased immediately before puberty, and remained low after puberty.

CONCLUSIONS

Deficiency of MKRN3 causes central precocious puberty in humans. (Funded by the National Institutes of Health and others.).

GnRH pulse frequency-dependent stimulation of FSHβ transcription is mediated via activation of PKA and CREB

Expression of pituitary FSH and LH, under the control of pulsatile GnRH, is essential for fertility. cAMP response element-binding protein (CREB) has been implicated in the regulation of FSHβ gene expression, but the molecular mechanisms by which pulsatile GnRH regulates CREB activation remain poorly understood. We hypothesized that CREB is activated by a distinct signaling pathway in response to pulsatile GnRH in a frequency-dependent manner to dictate the FSHβ transcriptional response. GnRH stimulation of CREB phosphorylation (pCREB) in the gonadotrope-derived LβT2 cell line was attenuated by a protein kinase A (PKA) inhibitor, H89. A dominant negative PKA (DNPKA) reduced GnRH-stimulated pCREB and markedly decreased GnRH stimulation of FSHβ mRNA and FSHβLUC activity, but had little effect on LHβLUC activity, indicating relative specificity of this pathway. In perifusion studies, FSHβ mRNA levels and FSHβLUC activities were increased by pulsatile GnRH, with significantly greater increases at low compared with high pulse frequencies. DNPKA markedly reduced these GnRH-stimulated FSHβ responses at both low and high pulse frequencies. Correlating with FSHβ activation, both PKA activity and levels of pCREB were increased to a greater extent by low compared with high GnRH pulse frequencies, and the induction of pCREB was also attenuated by overexpression of DNPKA at both low and high pulse frequencies. Taken together, these data indicate that a PKA-mediated signaling pathway mediates GnRH activation of CREB at low-pulse frequencies, playing a significant role in the decoding of the hypothalamic GnRH signal to result in frequency-dependent FSHβ activation.

Increased neurokinin B (Tac2) expression in the mouse arcuate nucleus is an early marker of pubertal onset with differential sensitivity to sex steroid-negative feedback than Kiss1

At puberty, neurokinin B (NKB) and kisspeptin (Kiss1) may help to amplify GnRH secretion, but their precise roles remain ambiguous. We tested the hypothesis that NKB and Kiss1 are induced as a function of pubertal development, independently of the prevailing sex steroid milieu. We found that levels of Kiss1 mRNA in the arcuate nucleus (ARC) are increased prior to the age of puberty in GnRH/sex steroid-deficient hpg mice, yet levels of Kiss1 mRNA in wild-type mice remained constant, suggesting that sex steroids exert a negative feedback effect on Kiss1 expression early in development and across puberty. In contrast, levels of Tac2 mRNA, encoding NKB, and its receptor (NK3R; encoded by Tacr3) increased as a function of puberty in both wild-type and hpg mice, suggesting that during development Tac2 is less sensitive to sex steroid-dependent negative feedback than Kiss1. To compare the relative responsiveness of Tac2 and Kiss1 to the negative feedback effects of gonadal steroids, we examined the effect of estradiol (E(2)) on Tac2 and Kiss1 mRNA and found that Kiss1 gene expression was more sensitive than Tac2 to E(2)-induced inhibition at both juvenile and adult ages. This differential estrogen sensitivity was tested in vivo by the administration of E(2). Low levels of E(2) significantly suppressed Kiss1 expression in the ARC, whereas Tac2 suppression required higher E(2) levels, supporting differential sensitivity to E(2). Finally, to determine whether inhibition of NKB/NK3R signaling would block the onset of puberty, we administered an NK3R antagonist to prepubertal (before postnatal d 30) females and found no effect on markers of pubertal onset in either WT or hpg mice. These results indicate that the expression of Tac2 and Tacr3 in the ARC are markers of pubertal activation but that increased NKB/NK3R signaling alone is insufficient to trigger the onset of puberty in the mouse.

Numb regulates glioma stem cell fate and growth by altering epidermal growth factor receptor and Skp1-Cullin-F-box ubiquitin ligase activity

Glioblastoma contains a hierarchy of stem-like cancer cells, but how this hierarchy is established is unclear. Here, we show that asymmetric Numb localization specifies glioblastoma stem-like cell (GSC) fate in a manner that does not require Notch inhibition. Numb is asymmetrically localized to CD133-hi GSCs. The predominant Numb isoform, Numb4, decreases Notch and promotes a CD133-hi, radial glial-like phenotype. However, upregulation of a novel Numb isoform, Numb4 delta 7 (Numb4d7), increases Notch and AKT activation while nevertheless maintaining CD133-hi fate specification. Numb knockdown increases Notch and promotes growth while favoring a CD133-lo, glial progenitor-like phenotype. We report the novel finding that Numb4 (but not Numb4d7) promotes SCF(Fbw7) ubiquitin ligase assembly and activation to increase Notch degradation. However, both Numb isoforms decrease epidermal growth factor receptor (EGFR) expression, thereby regulating GSC fate. Small molecule inhibition of EGFR activity phenocopies the effect of Numb on CD133 and Pax6. Clinically, homozygous NUMB deletions and low Numb mRNA expression occur primarily in a subgroup of proneural glioblastomas. Higher Numb expression is found in classical and mesenchymal glioblastomas and correlates with decreased survival. Thus, decreased Numb promotes glioblastoma growth, but the remaining Numb establishes a phenotypically diverse stem-like cell hierarchy that increases tumor aggressiveness and therapeutic resistance.

Evidence of the importance of the first intracellular loop of prokineticin receptor 2 in receptor function

Prokineticin receptors (PROKR) are G protein-coupled receptors (GPCR) that regulate diverse biological processes, including olfactory bulb neurogenesis and GnRH neuronal migration. Mutations in PROKR2 have been described in patients with varying degrees of GnRH deficiency and are located in diverse functional domains of the receptor. Our goal was to determine whether variants in the first intracellular loop (ICL1) of PROKR2 (R80C, R85C, and R85H) identified in patients with hypogonadotropic hypogonadism interfere with receptor function and to elucidate the mechanisms of these effects. Because of structural homology among GPCR, clarification of the role of ICL1 in PROKR2 activity may contribute to a better understanding of this domain across other GPCR. The effects of the ICL1 PROKR2 mutations on activation of signal transduction pathways, ligand binding, and receptor expression were evaluated. Our results indicated that the R85C and R85H PROKR2 mutations interfere only modestly with receptor function, whereas the R80C PROKR2 mutation leads to a marked reduction in receptor activity. Cotransfection of wild-type (WT) and R80C PROKR2 showed that the R80C mutant could exert a dominant negative effect on WT PROKR2 in vitro by interfering with WT receptor expression. In summary, we have shown the importance of Arg80 in ICL1 for PROKR2 expression and demonstrate that R80C PROKR2 exerts a dominant negative effect on WT PROKR2.

Cerebrospinal fluid biomarkers in idiopathic normal pressure hydrocephalus

The diagnosis of idiopathic normal pressure hydrocephalus (iNPH) is still challenging. Alzheimer's disease (AD), along with vascular dementia, the most important differential diagnosis for iNPH, has several potential cerebrospinal fluid (CSF) biomarkers which might help in the selection of patients for shunt treatment. The aim of this study was to compare a battery of CSF biomarkers including well-known AD-related proteins with CSF from patients with suspected iNPH collected from the external lumbar drainage test (ELD). A total of 35 patients with suspected iNPH patients were evaluated with ELD. CSF was collected in the beginning of the test, and the concentrations of total tau, ptau(181), Aβ(42), NFL, TNF-α, TGFβ1, and VEGF were analysed by ELISA. Twenty-six patients had a positive ELD result-that is, their gait symptoms improved; 9 patients had negative ELD. The levels of all analyzed CSF biomarkers were similar between the groups and none of them predicted the ELD result in these patients. Contrary to expectations lumbar CSF TNF-α concentration was low in iNPH patients.

Reproductive hormone-dependent and -independent contributions to developmental changes in kisspeptin in GnRH-deficient hypogonadal mice

Kisspeptin is a potent activator of GnRH-induced gonadotropin secretion and is a proposed central regulator of pubertal onset. In mice, there is a neuroanatomical separation of two discrete kisspeptin neuronal populations, which are sexually dimorphic and are believed to make distinct contributions to reproductive physiology. Within these kisspeptin neuron populations, Kiss1 expression is directly regulated by sex hormones, thereby confounding the roles of sex differences and early activational events that drive the establishment of kisspeptin neurons. In order to better understand sex steroid hormone-dependent and -independent effects on the maturation of kisspeptin neurons, hypogonadal (hpg) mice deficient in GnRH and its downstream effectors were used to determine changes in the developmental kisspeptin expression. In hpg mice, sex differences in Kiss1 mRNA levels and kisspeptin immunoreactivity, typically present at 30 days of age, were absent in the anteroventral periventricular nucleus (AVPV). Although immunoreactive kisspeptin increased from 10 to 30 days of age to levels intermediate between wild type (WT) females and males, corresponding increases in Kiss1 mRNA were not detected. In contrast, the hpg arcuate nucleus (ARC) demonstrated a 10-fold increase in Kiss1 mRNA between 10 and 30 days in both females and males, suggesting that the ARC is a significant center for sex steroid-independent pubertal kisspeptin expression. Interestingly, the normal positive feedback response of AVPV kisspeptin neurons to estrogen observed in WT mice was lost in hpg females, suggesting that exposure to reproductive hormones during development may contribute to the establishment of the ovulatory gonadotropin surge mechanism. Overall, these studies suggest that the onset of pubertal kisspeptin expression is not dependent on reproductive hormones, but that gonadal sex steroids critically shape the hypothalamic kisspeptin neuronal subpopulations to make distinct contributions to the activation and control of the reproductive hormone cascade at the time of puberty.

SNAI2/Slug promotes growth and invasion in human gliomas

Background

Numerous factors that contribute to malignant glioma invasion have been identified, but the upstream genes coordinating this process are poorly known.

Methods

To identify genes controlling glioma invasion, we used genome-wide mRNA expression profiles of primary human glioblastomas to develop an expression-based rank ordering of 30 transcription factors that have previously been implicated in the regulation of invasion and metastasis in cancer.

Results

Using this approach, we identified the oncogenic transcriptional repressor, SNAI2/Slug, among the upper tenth percentile of invasion-related transcription factors overexpressed in glioblastomas. SNAI2 mRNA expression correlated with histologic grade and invasive phenotype in primary human glioma specimens, and was induced by EGF receptor activation in human glioblastoma cells. Overexpression of SNAI2/Slug increased glioblastoma cell proliferation and invasion in vitro and promoted angiogenesis and glioblastoma growth in vivo. Importantly, knockdown of endogenous SNAI2/Slug in glioblastoma cells decreased invasion and increased survival in a mouse intracranial human glioblastoma transplantation model.

Conclusion

This genome-scale approach has thus identified SNAI2/Slug as a regulator of growth and invasion in human gliomas.

Novel local drug delivery system using thermoreversible gel in combination with polymeric microspheres or liposomes

BACKGROUND

The purpose of our study was to evaluate the application of thermoreversible gelation polymer (TGP) as a local drug delivery system for malignant glioma.

MATERIALS AND METHODS

Polymeric microspheres or liposomes loaded with doxorubicin (sphere-dox or lipo-dox) were combined with TGP to provide continuous drug delivery of doxorubicin (dox) for kinetic release studies and cell viability assays on glioma cell lines in vitro. For in vivo studies, TGP loaded with dox alone (TGP-dox) was combined with sphere-dox or lipo-dox. Their antitumor effects on subcutaneous human glioma xenografts were evaluated in nude mice.

RESULTS

In vitro, TGP combined with sphere-dox or lipo-dox released dox for up to 30 days. In vivo, TGP-dox combined with sphere-dox or lipo-dox inhibited subcutaneous glioma tumor growth until day 32 and day 38, respectively.

CONCLUSION

TGP in combination with microspheres or liposomes successfully prolonged the release of dox and its antitumor effects.

Bio-printing of collagen and VEGF-releasing fibrin gel scaffolds for neural stem cell culture

Time-released delivery of soluble growth factors (GFs) in engineered hydrogel tissue constructs promotes the migration and proliferation of embedded cells, which is an important factor for designing scaffolds that ultimately aim for neural tissue regeneration. We report a tissue engineering technique to print murine neural stem cells (C17.2), collagen hydrogel, and GF (vascular endothelial growth factor: VEGF)-releasing fibrin gel to construct an artificial neural tissue. We examined the morphological changes of the printed C17.2 cells embedded in the collagen and its migration toward the fibrin gel. The cells showed high viability (92.89+/-2.32%) after printing, which was equivalent to that of manually-plated cells. C17.2 cells printed within 1mm from the border of VEGF-releasing fibrin gel showed GF-induced changes in their morphology. The cells printed in this range also migrated toward the fibrin gel, with the total migration distance of 102.4+/-76.1microm over 3days. The cells in the control samples (fibrin without the VEGF or VEGF printed directly in collagen) neither proliferated nor migrated. The results demonstrated that bio-printing of VEGF-containing fibrin gel supported sustained release of the GF in the collagen scaffold. The presented method can be gainfully used in the development of three-dimensional (3D) artificial tissue assays and neural tissue regeneration applications.

Targeting rat brainstem glioma using human neural stem cells and human mesenchymal stem cells

PURPOSE

Brainstem gliomas are usually inoperable and have a dismal prognosis. Based on the robust tropisms of neural stem cells (NSC) and mesenchymal stem cells (MSC) to brain tumors, we compared the tumor-tropic migratory capacities of these stem cells and evaluated the therapeutic potential of genetically engineered human NSCs encoding cytosine deaminase (CD) and IFNbeta against brainstem gliomas.

EXPERIMENTAL DESIGN

The directed migratory capacities of NSCs and MSCs to brainstem glioma (F98) were evaluated both in vitro and in vivo. The human NSCs (HB1.F3) and various human MSCs, such as bone marrow-derived MSCs (HM3.B10), adipose tissue-derived MSCs, and umbilical cord blood-derived MSCs, were tested. Human fibroblast cells (HFF-1) were used as the negative control. As a proof of concept, the bioactivity of HB1.F3-CD-IFNbeta was analyzed with a cell viability assay, and animals with brainstem gliomas were injected with HB1.F3-CD-IFNbeta cells followed by systemic 5-fluorocytosine treatment.

RESULTS

In an in vitro modified Transwell migration assay and in vivo stem cell injection into established brainstem gliomas in rats, all the stem cells showed a significant migratory capacity compared with that of the control (P < 0.01). Histologic analysis showed a 59% reduction in tumor volume in the HB1.F3-CD-IFNbeta-treated group (P < 0.05). Apoptotic cells were increased 2.33-fold in animals treated with HB1.F3-CD-IFNbeta compared with the respective control groups (P < 0.01).

CONCLUSION

The brainstem glioma-tropic migratory capacities of MSCs from various sources were similar to those of NSCs. Genetically engineered NSCs show therapeutic efficacy against brainstem gliomas.

Expression of a gonadotropin-releasing hormone receptor-simian virus 40 T-antigen transgene has sex-specific effects on the reproductive axis

The GnRH receptor (GnRHR) responds to pulsatile GnRH signals to coordinate pituitary gonadotropin synthesis and secretion. Previously, a 1.2-kb fragment of the 5'-flanking region isolated from the mouse GnRHR gene was shown to target expression to pituitary gonadotropes in vivo. The 1.2-kb gene promoter fused to the simian virus 40 large T antigen (TAg) was used to generate transgenic mice that form gonadotrope-derived pituitary tumors at 4-5 months of age. Transgenic female mice have hypogonadotropic hypogonadism, infantile gonads, and are infertile throughout their life span, whereas males remain reproductively intact until their tumors become large. We hypothesized that the targeted TAg expression causes a sex-specific disruption of the reproductive axis at the level of the pituitary gland. To test this hypothesis, we characterized the pituitary gonadotropin beta-subunit and TAg expression patterns, and measured plasma gonadotropin and gonadal steroid levels in female and male mice before and after pituitary tumor development. TAg expression was observed in transgenic females and males 15 d of age, before tumor development. Interestingly, and in contrast to the transgenic males, pituitary LH beta and FSH beta subunit protein levels, and plasma LH and FSH levels, were reduced in transgenic females. Reproductive organs in transgenic female mice remained underdeveloped but were normal in transgenic males. We conclude that the expression of the TAg transgene driven by the GnRHR gene promoter results in female-specific infertility due to disruption of gonadotropin production and secretion even before tumor development.