Probes for INS

Major depressive disorder (MDD) patients display a common but often variable set of symptoms making successful, sustained treatment difficult to achieve. Separate depressive symptoms may be encoded by differential changes in distinct circuits in the brain, yet how discrete circuits underlie behavioral subsets of depression and how they adapt in response to stress has not been addressed. We identify two discrete circuits of parvalbumin-positive (PV) neurons in the ventral pallidum (VP) projecting to either the lateral habenula or ventral tegmental area contributing to depression. We find that these populations undergo different electrophysiological adaptations in response to social defeat stress, which are normalized by antidepressant treatment. Furthermore, manipulation of each population mediates either social withdrawal or behavioral despair, but not both. We propose that distinct components of the VP PV circuit can subserve related, yet separate depressive-like phenotypes in mice, which could ultimately provide a platform for symptom-specific treatments of depression.

Deep penetrating nevus (DPN) is characterized by enlarged, pigmented melanocytes that extend through the dermis. DPN can be difficult to distinguish from melanoma but rarely displays aggressive biological behavior. Here, we identify a combination of mutations of the β-catenin and mitogen-activated protein kinase pathways as characteristic of DPN. Mutations of the β-catenin pathway change the phenotype of a common nevus with BRAF mutation into that of DPN, with increased pigmentation, cell volume and nuclear cyclin D1 levels. Our results suggest that constitutive β-catenin pathway activation promotes tumorigenesis by overriding dependencies on the microenvironment that constrain proliferation of common nevi. In melanoma that arose from DPN we find additional oncogenic alterations. We identify DPN as an intermediate stage in the step-wise progression from nevus to melanoma. In summary, we delineate specific genetic alterations and their sequential order, information that can assist in the diagnostic classification and grading of these distinctive neoplasms.Deep penetrating nevi (DPN) are unusual melanocytic neoplasms with unknown genetic drivers. Here the authors show that majority of DPN harbor activating mutations in the β-catenin and the MAP-kinase pathways; this characteristic can help in the classification and grading of these distinctive neoplasms.

Lgr5+ stem cells are crucial to gut epithelium homeostasis; however, how these cells are maintained is not fully understood. Zinc finger HIT-type containing 1 (Znhit1) is an evolutionarily conserved subunit of the SRCAP chromosome remodeling complex. Currently, the function of Znhit1 in vivo and its working mechanism in the SRCAP complex are unknown. Here we show that deletion of Znhit1 in intestinal epithelium depletes Lgr5+ stem cells thus disrupts intestinal homeostasis postnatal establishment and maintenance. Mechanistically, Znhit1 incorporates histone variant H2A.Z into TSS region of genes involved in Lgr5+ stem cell fate determination, including Lgr5, Tgfb1 and Tgfbr2, for subsequent transcriptional regulation. Importantly, Znhit1 promotes the interaction between H2A.Z and YL1 (H2A.Z chaperone) by controlling YL1 phosphorylation. These results demonstrate that Znhit1/H2A.Z is essential for Lgr5+ stem cell maintenance and intestinal homeostasis. Our findings identified a dominant role of Znhit1/H2A.Z in controlling mammalian organ development and tissue homeostasis in vivo.

The lateral habenula (LHb) has a key role in integrating a variety of neural circuits associated with reward and aversive behaviors. There is limited information about how the different cell types and neuronal circuits within the LHb coordinate physiological and motivational states. Here, we report a cell type in the medial division of the LHb (LHbM) in male rats that is distinguished by: (1) a molecular signature for GABAergic neurotransmission (Slc32a1/VGAT) and estrogen receptor (Esr1/ERα) expression, at both mRNA and protein levels, as well as the mRNA for vesicular glutamate transporter Slc17a6/VGLUT2, which we term the GABAergic estrogen-receptive neuron (GERN); (2) its axonal projection patterns, identified by in vivo juxtacellular labeling, to both local LHb and to midbrain modulatory systems; and (3) its somatic expression of receptors for vasopressin, serotonin and dopamine, and mRNA for orexin receptor 2. This cell type is anatomically located to receive afferents from midbrain reward (dopamine and serotonin) and hypothalamic water and energy homeostasis (vasopressin and orexin) circuits. These afferents shared the expression of estrogen synthase (aromatase) and VGLUT2, both in their somata and axon terminals. We demonstrate dynamic changes in LHbM VGAT+ cell density, dependent upon gonadal functional status, that closely correlate with motivational behavior in response to predator and forced swim stressors. The findings suggest that the homeostasis and reward-related glutamatergic convergent projecting pathways to LHbMC employ a localized neurosteroid signaling mechanism via axonal expression of aromatase, to act as a switch for GERN excitation/inhibition output prevalence, influencing depressive or motivated behavior.

The rat nucleus incertus (NI) contains GABA/peptide-projection neurons responsive to orexin (hypocretin)/orexin receptor-2 (OX2) signalling. Melanin-concentrating hormone (MCH) and orexin neurons often innervate and influence common target areas. Therefore, we assessed the relationship between these hypothalamic peptidergic systems and rat NI, by investigating the presence of an MCH innervation and MCH receptor-1 (MCH1) expression, and neurophysiological and behavioural effects of MCH c.f. orexin-A (OXA), within the NI. We identified lateral hypothalamus (LH), perifornical and sub-zona incerta MCH neurons that innervate NI, and characterised the rostrocaudal distribution of MCH-containing fibres in NI. Single-cell RT-PCR detected MCH1 and OX2 mRNA in NI, and multiplex, fluorescent in situ hybridisation revealed distinct co-expression patterns of MCH1 and OX2 mRNA in NI neurons expressing vesicular GABA transporter (vGAT) mRNA. Patch-clamp recordings revealed 34% of NI neurons tested were hyperpolarised by MCH (1 μM), representing a distinct population from OXA-sensitive NI neurons (35%). Intra-NI OXA infusion (600 pmol) in satiated rats during the light/inactive phase produced increased locomotor activity and food (standard chow) intake, whereas intra-NI MCH infusion (600 pmol) produced only a trend for decreased locomotor activity and no effect on food intake. Furthermore, in satiated or pre-fasted rats tested during the dark/active phase, intra-NI infusion of MCH did not alter the elevated locomotor activity or higher food intake observed. However, quantification of neuropeptide-immunostaining revealed differential diurnal fluctuations in orexin and MCH trafficking to NI. Our findings identify MCH and orexin inputs onto divergent NI populations which may differentially influence arousal and motivated behaviours.