Neurokinin 3 receptor forms a complex with acetylated histone H3 and H4 in hypothalamic neurons following hyperosmotic challenge

Abstract

The neurokinin 3 receptor (NK3R) is a G protein-coupled receptor that is expressed in brain and is highly expressed by magnocellular vasopressinergic neurons in both the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus. Hyperosmolarity causes a ligand-mediated internalization of NK3Rs to the cytoplasm and to the nuclei of vasopressinergic PVN neurons. This receptor activation-dependent pathway is presumed to be a means to directly transmit synaptic signals from the cell membrane to the nucleus. The present study evaluated in vivo the subnuclear domains that associate with NK3R. Rats were administered 2 M NaCl (intragastric) or no intragastric load, and 40 min later, the PVN was dissected and nuclei were isolated. Using double-immuno-transmission electron microscopy (TEM), we show that, compared with controls, hyperosmolarity causes a significant increase in NK3R Immunogold beads in the nucleus of PVN neurons. Furthermore, NK3R spatially colocalized with histone H4 and with highly acetylated H4 in nuclei isolated from the PVN of rats administered 2 M NaCl, but not in nuclei from control rats. Next, coimmunoprecipitation experiments showed that acetylated H4, as well as acetylated H3, were pulled down with NK3R in the PVN nuclear enriched fraction from rats treated with 2 M NaCl, but not from control rats. In response to hyperosmolarity, NK3R is transported to the nucleus of PVN neurons and associates with transcriptionally active chromatin, where it may influence the transcription of genes.

Activation of tachykinin, neurokinin 3 receptors affects chromatin structure and gene expression by means of histone acetylation

“…Previous results show that injections of senktide cause the activation and internalization of NK3R to the cytoplasm and cell nucleus [23, 28]. Furthermore, activation of NK3R by hyperosmolarity causes the translocation of NK3R expressed by hypothalamic neurons to the nucleus where it associates with acetylated H3 and H4 [17, 23]. The present results show that NK3R activation plays a role in the regulation of transcription by modifying chromatin structure through the acetylation of core histones.…”

“…First, we showed using immuno-electron microscopy and immunoprecipitation that NK3R is translocated to the nuclei of hypothalamic neurons in an activity-dependent fashion, and there it associates with acetylated H3 and H4 [17]. Second, NK3R activates the IP3 and adenylate cyclase signaling pathway [39] that affect acetylation and chromatin structure [43].…”

“…In animal studies, hyperosmolarity causes NK3R to be translocated to the nucleus of hypothalamic neurons where it associates with acetylated H3 and H4 [17]. The induction of c-fos involves the acetylation of H3 and H4 at the c-fos promoter [66].…”

“…Transport of NK3R through the nuclear pore complex and into the nucleus is mediated by importin beta [31]. Once within the nucleus, co-immunoprecipitation and double immune-electron microscopy show that nuclear NK3R associates with acetylated histone H4 and H3 [17]. Thus, in addition to traditional second messenger signaling cascades, ligand-induced trafficking of NK3R to the nucleus may directly regulate gene expression.…”

Stress-induced dendritic internalization and nuclear translocation of the neurokinin-3 (NK3) receptor in vasopressinergic profiles of the rat paraventricular nucleus of the hypothalamus

“…The antiserum was tested for specificity using techniques of siRNA, co-immunoprecipitation and Western blot (Jensen et al, 2010). The antiserum showed a band around 60-75 kDa; a molecular weight corresponding to the NK 3 R (Jensen et al, 2008;Flynn et al, 2011;Sladek et al, 2011). As compared to the NK 3 R immunolabeling produced by a commercial NK 3 R antiserum (Misono and Lessard, 2012), the present anti-sheep NK 3 R antiserum produced a similar distribution in PVN somatodendritic profiles either by light (single immunoperoxidase) or electron microscopy (immunogold or immunoperoxidase).…”