Biology subjects

Kannangara, H.

Publications and source records attributed to Kannangara, H..

4 recordsLinked to original sources

bioRxiv2024

Single Transcript Level Atlas of Oxytocin and the Oxytocin Receptor in the Mouse Brain

Oxytocin (OXT), a primitive nonapeptide known to regulate reproduction and social behaviors, is synthesized primarily in the hypothalamus and is secreted via hypophyseal-portal system of the posterior pituitary gland. Given that pituitary hormones, traditionally thought of as regulators of single targets, display an array of central and peripheral actions, OXT also directly affects bone and body composition. Its effects on bone remodeling are physiologically relevant, as elevated OXT levels during pregnancy and lactation could cause calcium mobilization from the maternal skeleton for intergenerational calcium transfer towards fetal bone growth. There is an equally large body of evidence that has established the presence of OXT receptors (OXTRs) in the brain through which central functions, such as social bonding, and peripheral functions, such as the regulation of body composition, can be exerted. To purposefully address the effects of OXT on the brain, we used RNAscope to map OXT and OXTR expression, at the single transcript level, in the whole mouse brain. Identification of brain nuclei with the highest OXT and OXTR transcript density will shed further light on functional OXT nodes that could be further interrogated experimentally to define new physiologic circuitry.

physiology↗

bioRxiv2024

An Atlas of Brain-Bone Sympathetic Neural Circuits

There is clear evidence that the sympathetic nervous system (SNS) mediates bone metabolism. Histological studies show abundant SNS innervation of the periosteum and bone marrow--these nerves consist of noradrenergic fibers that immunostain for tyrosine hydroxylase, dopamine beta hydroxylase, or neuropeptide Y. Nonetheless, the brain sites that send efferent SNS outflow to bone have not yet been characterized. Using pseudorabies (PRV) viral transneuronal tracing, we report, for the first time, the identification of central SNS outflow sites that innervate bone. We find that the central SNS outflow to bone originates from 87 brain nuclei, sub-nuclei and regions of six brain divisions, namely the midbrain and pons, hypothalamus, hindbrain medulla, forebrain, cerebral cortex, and thalamus. We also find that certain sites, such as the raphe magnus (RMg) of the medulla and periaqueductal gray (PAG) of the midbrain, display greater degrees of PRV152 infection, suggesting that there is considerable site-specific variation in the levels of central SNS outflow to bone. This comprehensive compendium illustrating the central coding and control of SNS efferent signals to bone should allow for a greater understanding of the neural regulation of bone metabolism, and importantly and of clinical relevance, mechanisms for central bone pain.

neuroscience↗

bioRxiv2022

Brain Atlas for Glycoprotein Hormone Receptors at Single-Transcript Level

There is increasing evidence that anterior pituitary hormones, traditionally thought to have unitary functions in regulating single endocrine targets, act on multiple somatic tissues, such as bone, fat, and liver. There is also emerging evidence for anterior pituitary hormone action on brain receptors in mediating central neural and peripheral somatic functions. Here, we have created the most comprehensive neuroanatomical atlas on the expression of TSHRs, LHCGRs and FSHRs. We have used RNAscope, a technology that allows the detection of mRNA at single-transcript level, together with protein level validation, to document Tshr expression in 173 and Fshr expression in 353 brain regions, nuclei and sub-nuclei identified using the Atlas for the Mouse Brain in Stereotaxic Coordinates. We also identified Lhcgr transcripts in 401 brain regions, nuclei and sub-nuclei. Complementarily, we used ViewRNA, another single-transcript detection technology, to establish the expression of FSHRs in human brain samples, where transcripts were co-localized in MALAT1-positive neurons. In addition, we show high expression for all three receptors in the ventricular region--with yet unknown functions. Intriguingly, Tshr and Fshr expression in the ependymal layer of the third ventricle was similar to that of the thyroid follicular cells and testicular Sertoli cells, respectively. TSHRs were expressed specifically in tanycytes. In contrast, Fshrs were localized to NeuN-positive neurons in the granular layer of the dentate gyrus in murine and human brain--both are Alzheimers disease vulnerable regions. Our atlas thus provides a vital resource for scientists to explore the link between the stimulation or inactivation of brain glycoprotein hormone receptors on somatic function. New actionable pathways for human disease may be unmasked through further studies.

neuroscience↗

bioRxiv2022

A Single Multipurpose FSH-Blocking Therapeutic for Osteoporosis and Obesity

Pharmacological and genetic studies over the past decade have established FSH as an actionable target for diseases affecting millions, notably osteoporosis, obesity and Alzheimers disease (AD). Blocking FSH action prevents bone loss, fat gain and AD-like features in mice. We recently developed a first-in-class, humanized, epitope-specific FSH blocking antibody, MS-Hu6, with a KD of 7.52 nM. Using a GLP-compliant platform, we now report the efficacy of MS-Hu6 in preventing obesity and osteoporosis in mice, and parameters of acute safety in monkeys. Biodistribution studies using 89Zr-labelled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone, bone marrow and fat depots. MS-Hu6 displayed a {beta} phase t[1/2] of 13 days (316 hours) in humanized Tg32 mice, and bound endogenous FSH. We tested 215 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze-thaw and at different temperatures, with minimal aggregation, and without self-, cross-, or hydrophobic interactions or appreciable binding to relevant human antigens. MS-Hu6 showed the same level of "humanness" as human IgG1 in silico, and was non-immunogenic in ELISPOT assays for IL-2 and IFN{gamma} in human peripheral blood mononuclear cell cultures. We conclude that MS-Hu6 is efficacious, durable and manufacturable, and is therefore poised for future human testing as a multipurpose therapeutic.

pharmacology and toxicology↗