Probes for INS

The cytokine interleukin-1β (IL-1β) is known to stimulate proinflammatory immune responses and impair β-cell function and viability, all critical events in the pathogenesis of type 1 diabetes (T1D). Here we evaluate the effect of SER140, a small peptide IL-1β receptor antagonist, on diabetes progression and cellular pancreatic changes in female nonobese diabetic (NOD) mice. Eight weeks of treatment with SER140 reduced the incidence of diabetes by more than 50% compared with vehicle, decreased blood glucose, and increased plasma insulin. Additionally, SER140 changed the endocrine and immune cells dynamics in the NOD mouse pancreas. Together, the data suggest that SER140 treatment postpones the onset of diabetes in female NOD mice by interfering with IL-1β activated pathways.

Pituitary adenylate cyclase activating polypeptide (PACAP, Adcyap1) is a neuromodulator implicated in anxiety, metabolism and reproductive behavior. PACAP global knockout mice have decreased fertility and PACAP modulates LH release. However, its source and role at the hypothalamic level remain unknown. We demonstrate that PACAP-expressing neurons of the ventral premamillary nucleus of the hypothalamus (PMVPACAP) project to, and make direct contact with, kisspeptin neurons in the arcuate and AVPV/PeN nuclei and a subset of these neurons respond to PACAP exposure. Targeted deletion of PACAP from the PMV through stereotaxic virally mediated cre- injection or genetic cross to LepR-i-cre mice with Adcyap1fl/fl mice led to delayed puberty onset and impaired reproductive function in female, but not male, mice. We propose a new role for PACAP-expressing neurons in the PMV in the relay of nutritional state information to regulate GnRH release by modulating the activity of kisspeptin neurons, thereby regulating reproduction in female mice.

Recent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells (ISCs) and tumour-initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-κB pathway can drive dedifferentiation of intestinal cells lacking Apc. To investigate this process further, we profiled both cells undergoing dedifferentiation in vitro and tumours generated from these cells in vivo by gene expression analysis. Remarkably, no clear differences were observed in the tumours; however, during dedifferentiation in vitro we found a marked upregulation of TGFβ signalling, a pathway commonly mutated in colorectal cancer (CRC). Genetic inactivation of TGFβ type 1 receptor (Tgfbr1/Alk5) enhanced the ability of KrasG12D/+ mutation to drive dedifferentiation and markedly accelerated tumourigenesis. Mechanistically this is associated with a marked activation of MAPK signalling. Tumourigenesis from differentiated compartments is potently inhibited by MEK inhibition. Taken together, we show that tumours arising in differentiated compartments will be exposed to different suppressive signals, for example, TGFβ and blockade of these makes tumourigenesis more efficient from this compartment.

Circulating systemic factors can regulate adult neural stem cell (NSC) biology, but the identity of these circulating cues is still being defined. Here, we have focused on the cytokine interleukin-6 (IL-6), since increased circulating levels of IL-6 are associated with neural pathologies such as autism and bipolar disorder. We show that IL-6 promotes proliferation of post-natal murine forebrain NSCs and that, when the IL-6 receptor is inducibly knocked out in post-natal or adult neural precursors, this causes a long-term decrease in forebrain NSCs. Moreover, a transient circulating surge of IL-6 in perinatal or adult mice causes an acute increase in neural precursor proliferation followed by long-term depletion of adult NSC pools. Thus, IL-6 signaling is both necessary and sufficient for adult NSC self-renewal, and acute perturbations in circulating IL-6, as observed in many pathological situations, have long-lasting effects on the size of adult NSC pools.

Neurons containing melanin-concentrating hormone (MCH) in the posterior lateral hypothalamus play an integral role in rapid eye movement sleep (REMs) regulation. As MCH neurons also contain a variety of other neuropeptides [e.g., cocaine- and amphetamine-regulated transcript (CART) and nesfatin-1] and neurotransmitters (e.g., glutamate), the specific neurotransmitter responsible for REMs regulation is not known. We hypothesized that glutamate, the primary fast-acting neurotransmitter in MCH neurons, is necessary for REMs regulation. To test this hypothesis, we deleted vesicular glutamate transporter (Vglut2; necessary for synaptic release of glutamate) specifically from MCH neurons by crossing MCH-Cre mice (expressing Cre recombinase in MCH neurons) with Vglut2flox/flox mice (expressing LoxP-modified alleles of Vglut2), and studied the amounts, architecture and diurnal variation of sleep-wake states during baseline conditions. We then activated the MCH neurons lacking glutamate neurotransmission using chemogenetic methods and tested whether these MCH neurons still promoted REMs. Our results indicate that glutamate in MCH neurons contributes to normal diurnal variability of REMs by regulating the levels of REMs during the dark period, but MCH neurons can promote REMs even in the absence of glutamate.

Current understanding of the contribution of C1 neurons to blood pressure (BP) regulation derives predominantly from experiments carried out in anesthetized animals or reduced ex vivo preparations. Here we use ArchaerhodopsinT3.0 (ArchT) loss-of-function optogenetics to explore BP regulation by C1 neurons in intact unanesthetized rats. Using a lentivirus that expresses ArchT under the Phox2b-activated promoter PRSx8 (PRSx8-ArchT), ∼65% of transduced neurons were C1 (balance retrotrapezoid nucleus, RTN). Other rats received CaMKII-ArchT3.0 AAV2 (CaMKII-ArchT) which transduced C1 neurons and larger numbers of unidentified glutamatergic and GABAergic cells.Under anesthesia, ArchT-photoactivation reduced sympathetic nerve activity and BP and silenced/strongly inhibited most (7/12) putative C1 neurons. In unanesthetized PRSx8-ArchT-treated rats breathing room air, bilateral ArchT-photoactivation caused a very small BP reduction that was only slightly larger under hypercapnia (6% FiCO2) but was greatly enhanced during hypoxia (10 and 12% FiO2), after sino-aortic denervation, or during isoflurane anesthesia. Degree of hypotension correlated with percentage of ArchT-transduced C1 cells. ArchT-photoactivation produced similar BP changes in CaMKII-ArchT-treated rats. Photoactivation in PRSX8-ArchT rats reduced breathing frequency (FR); in CamKII-ArchT rats FR increased.We conclude that the BP drop elicited by ArchT activation resulted from C1 inhibition and was unrelated to breathing changes. C1 neurons have low activity under normoxia but their activation is important to BP stability during hypoxia or anesthesia and contributes greatly to the hypertension caused by baroreceptor deafferentation. Finally, C1 neurons are marginally activated by hypercapnia and the large breathing stimulation caused by this stimulus has very little impact on resting BP.SIGNIFICANCE STATEMENTC1 neurons (C1) are glutamatergic/peptidergic/catecholaminergic neurons located in the medulla oblongata, which may operate as a switchboard for differential, behavior-appropriate, activation of selected sympathetic efferents. Based largely on experimentation in anesthetized or reduced preparations, a rostrally-located subset of C1 may contribute to both BP stabilization and dysregulation (hypertension). Here we used Archaerhodopsin-based loss-of-function optogenetics to explore the contribution of these neurons to BP in conscious rats. The results suggest that C1 contributes little to resting BP under normoxia or hypercapnia, C1 discharge is continuously restrained by arterial baroreceptors and C1 activation is critical to stabilize BP under hypoxia or anesthesia. This optogenetic approach could also be useful to explore the role of C1 during specific behaviors or in hypertensive models.