Human β3-Adrenoreceptor is Resistant to Agonist-Induced Desensitization in Renal Epithelial Cells

Background/Aims: We recently showed that the β3-adrenoreceptor (β3AR) is expressed in mouse kidney collecting ducts (CD) cells along with the type-2 vasopressin receptor (AVPR2). Interestingly, a single injection of a β3AR selective agonist promotes a potent antidiuretic effect in mice. Before considering the feasibility of chronic β3AR agonism to induce antidiuresis in vivo, we aimed to evaluate in vitro the signaling and desensitization profiles of human β3AR. Methods: Human β3AR desensitization was compared with that of human AVPR2 in cultured renal cells. Video imaging and FRET experiments were performed to dissect β3AR signaling under acute and chronic stimulation. Plasma membrane localization of β3AR, AVPR2 and AQP2 after agonist stimulation was studied by confocal microscopy. Receptors degradation was evaluated by Western blotting. Results: In renal cells acute stimulation with the selective β3AR agonist mirabegron, induced a dose-dependent increase in cAMP. Interestingly, chronic exposure to mirabegron promoted a significant increase of intracellular cAMP up to 12 hours. In addition, a slow and slight agonist-induced internalization and a delayed downregulation of β3AR was observed under chronic stimulation. Furthermore, chronic exposure to mirabegron promoted apical expression of AQP2 also up to 12 hours. Conversely, long-term stimulation of AVPR2 with dDAVP showed short-lasting receptor signaling, rapid internalization and downregulation and apical AQP2 expression for no longer than 3 h. Conclusions: Overall, we conclude that β3AR is less prone than AVPR2 to agonist-induced desensitization in renal collecting duct epithelial cells, showing sustained cAMP production, preserved membrane localization and delayed degradation after 12 hours agonist exposure. These results may be important for the potential use of chronic pharmacological stimulation of β3AR to promote antidiuresis overcoming in vivo renal concentrating defects caused by inactivating mutations of the AVPR2

The expression of Lamin A mutant R321X leads to endoplasmic reticulum stress with aberrant Ca(2+) handling

Mutations in the Lamin A/C gene (LMNA), which encodes A-type nuclear Lamins, represent the most frequent genetic cause of dilated cardiomyopathy (DCM). This study is focused on a LMNA nonsense mutation (R321X) identified in several members of an Italian family that produces a truncated protein isoform, which co-segregates with a severe form of cardiomyopathy with poor prognosis. However, no molecular mechanisms other than nonsense mediated decay of the messenger and possible haploinsufficiency were proposed to explain DCM. Aim of this study was to gain more insights into the disease-causing mechanisms induced by the expression of R321X at cellular level. We detected the expression of R321X by Western blotting from whole lysate of a mutation carrier heart biopsy. When expressed in HEK293 cells, GFP- (or mCherry)-tagged R321X mislocalized in the endoplasmic reticulum (ER) inducing the PERK-CHOP axis of the ER stress response. Of note, confocal microscopy showed phosphorylation of PERK in sections of the mutation carrier heart biopsy. ER mislocalization of mCherry-R321X also induced impaired ER Ca(2+) handling, reduced capacitative Ca(2+) entry at the plasma membrane and abnormal nuclear Ca(2+) dynamics. In addition, expression of R321X by itself increased the apoptosis rate. In conclusion, R321X is the first LMNA mutant identified to date, which mislocalizes into the ER affecting cellular homeostasis mechanisms not strictly related to nuclear functions

Fostering quality of life in young adults living with multiple sclerosis: a pilot study of a co-created integrated intervention

Introduction: Multiple sclerosis (MS) is generally diagnosed at an early age, making the acceptance of this chronic disease challenging. Research dedicated to young adults with MS (YawMS) is still limited. A biopsychosocial co-created intervention for YawMS integrating social, physical and psychological activities was developed (ESPRIMO intervention) in order to improve the quality of life (QoL) and well-being. This pre-post intervention assessment study examines the feasibility of the ESPRIMO intervention and its signal of efficacy. Methods: Inclusion criteria were: age 18-45 years, MS diagnosis, Expanded Disability Status Scale score < 3.5. After giving informed consent, YawMS completed a battery of questionnaires, which was repeated after the intervention. The battery included a bespoke feasibility scale, the COOP/WONCA charts, and the Short Form-12 Health Survey (SF-12). Results: Fifty-three YAwMS were enrolled and 43 (81.1%) completed the intervention. The majority of the sample positively rated the pleasantness, usefulness and feasibility of the intervention. A significant change in the COOP/WONCA "general QoL" chart (t = 3.65; p < 0.01) and SF-12 mental wellbeing component (t = -3.17; p < 0.01) was found. Discussion: ESPRIMO is an innovative intervention that is feasible; preliminary results show an improvement in QoL and mental wellbeing. Further studies are needed to test its efficacy and evaluate future implementation in health services.Clinical trial registration: ClinicalTrials.gov, NCT04431323

Everything You Always Wanted to Know about β₃-AR * (* But Were Afraid to Ask)

The beta-3 adrenergic receptor (β3-AR) is by far the least studied isotype of the beta-adrenergic sub-family. Despite its study being long hampered by the lack of suitable animal and cellular models and inter-species differences, a substantial body of literature on the subject has built up in the last three decades and the physiology of β3-AR is unraveling quickly. As will become evident in this work, β3-AR is emerging as an appealing target for novel pharmacological approaches in several clinical areas involving metabolic, cardiovascular, urinary, and ocular disease. In this review, we will discuss the most recent advances regarding β3-AR signaling and function and summarize how these findings translate, or may do so, into current clinical practice highlighting β3-AR’s great potential as a novel therapeutic target in a wide range of human conditions

The expression of Lamin A mutant R321X leads to endoplasmic reticulum stress with aberrant Ca(2+) handling

Mutations in the Lamin A/C gene (LMNA), which encodes A-type nuclear Lamins, represent the most frequent genetic cause of dilated cardiomyopathy (DCM). This study is focused on a LMNA nonsense mutation (R321X) identified in several members of an Italian family that produces a truncated protein isoform, which co-segregates with a severe form of cardiomyopathy with poor prognosis. However, no molecular mechanisms other than nonsense mediated decay of the messenger and possible haploinsufficiency were proposed to explain DCM. Aim of this study was to gain more insights into the disease-causing mechanisms induced by the expression of R321X at cellular level. We detected the expression of R321X by Western blotting from whole lysate of a mutation carrier heart biopsy. When expressed in HEK293 cells, GFP- (or mCherry)-tagged R321X mislocalized in the endoplasmic reticulum (ER) inducing the PERK-CHOP axis of the ER stress response. Of note, confocal microscopy showed phosphorylation of PERK in sections of the mutation carrier heart biopsy. ER mislocalization of mCherry-R321X also induced impaired ER Ca(2+) handling, reduced capacitative Ca(2+) entry at the plasma membrane and abnormal nuclear Ca(2+) dynamics. In addition, expression of R321X by itself increased the apoptosis rate. In conclusion, R321X is the first LMNA mutant identified to date, which mislocalizes into the ER affecting cellular homeostasis mechanisms not strictly related to nuclear functions

β3 adrenergic receptor in the kidney may be a new player in sympathetic regulation of renal function

To date, the study of the sympathetic regulation of renal function has been restricted to the important contribution of β1- and β2-adrenergic receptors (ARs). Here we investigate the expression and the possible physiologic role of β3-adrenergic receptor (β3-AR) in mouse kidney. The β3-AR is expressed in most of the nephron segments that also express the type 2 vasopressin receptor (AVPR2), including the thick ascending limb and the cortical and outer medullary collecting duct. Ex vivo experiments in mouse kidney tubules showed that β3-AR stimulation with the selective agonist BRL37344 increased intracellular cAMP levels and promoted 2 key processes in the urine concentrating mechanism. These are accumulation of the water channel aquaporin 2 at the apical plasma membrane in the collecting duct and activation of the Na-K-2Cl symporter in the thick ascending limb. Both effects were prevented by the β3-AR antagonist L748,337 or by the protein kinase A inhibitor H89. Interestingly, genetic inactivation of β3-AR in mice was associated with significantly increased urine excretion of water, sodium, potassium, and chloride. Stimulation of β3-AR significantly reduced urine excretion of water and the same electrolytes. Moreover, BRL37344 promoted a potent antidiuretic effect in AVPR2-null mice. Thus, our findings are of potential physiologic importance as they uncover the antidiuretic effect of β3-AR stimulation in the kidney. Hence, β3-AR agonism might be useful to bypass AVPR2-inactivating mutations

Spilanthol from Acmella oleracea lowers the intracellular levels of cAMP impairing NKCC2 phosphorylation and water channel AQP2 membrane expression in mouse kidney

Acmella oleracea is well recognized in Brazilian traditional medicine as diuretic, although few scientific data have been published to support this effect. Aim of this study was to determine the molecular effect of Acmella oleracea extract and its main alkylamide spilanthol on two major processes involved in the urine concentrating mechanism: Na-K-2Cl symporter (NKCC2) activity in the thick ascending limb and water channel aquaporin 2 accumulation at the apical plasma membrane of collecting duct cells. Phosphorylation of NKCC2 was evaluated as index of its activation by Western blotting. Rate of aquaporin 2 apical expression was analyzed by confocal laser microscopy. Spilanthol-induced intracellular signalling events were dissected by video-imaging experiments. Exposure to spilanthol reduced the basal phosphorylation level of NKCC2 both in freshly isolated mouse kidney slices and in NKCC2-expresing HEK293 cells. In addition, exposure to spilanthol strongly reduced both desmopressin and low Cl--dependent increase in NKCC2 phosphorylation in mouse kidney slices and NKCC2-expressing HEK293 cells, respectively. Similarly, spilanthol reduced both desmopressin- and forskolin-stimulated aquaporin 2 accumulation at the apical plasma membrane of collecting duct in mouse kidney slice and MCD4 cells, respectively. Of note, when orally administered, spilanthol induced a significant increase in both urine output and salt urinary excretion associated with a markedly reduced urine osmolality compared with control mice. Finally, at cellular level, spilanthol rapidly reduced or reversed basal and agonist-increased cAMP levels through a mechanism involving increases in intracellular [Ca2+]. In conclusion, spilanthol-induced inhibition of cAMP production negatively modulates urine-concentrating mechanisms thus holding great promise for its use as diuretic

e-ESPRIMO: An e-health biopsychosocial intervention for young adults with Multiple sclerosis and medium/high disability. Co-creation phase

Multiple Sclerosis (MS) is a neurodegenerative disease commonly diagnosed when young, which strongly impacts personal development and health-related quality of life (HRQoL). Starting from the promising results obtained from the ESPRIMO project, a co-created biopsychosocial intervention for young adults with MS, we aimed to design, together with experts in MS and medium-high disability, an e-Health biopsychosocial intervention to assess the needs of the targeted population and the benefits of the telematics tool. The feasibility of the intervention will later be tested on a pilot sample

Spilanthol decreases apical plasma membrane expression of AQP2 in freshly isolated kidney slices and MCD4 cells.

<p><b>(A)</b> Immunofluorescence analysis of AQP2 subcellular localization in freshly isolated kidney slices in resting condition (Ctr), after 100 μg/ml spilanthol stimulation (Spil), and after incubation with dDAVP in the absence (dDAVP) or in the presence of the spilanthol (Spil + dDAVP). Compared to Ctr and Spil conditions, dDAVP redistributed AQP2 staining to the apical plasma membrane. Of note, spilanthol prevented the dDAVP-induced effect on AQP2 membrane accumulation. Bar = 30 μm. <b>(B)</b> Immunofluorescence analysis of AQP2 subcellular localization in MCD4 renal cells in resting condition and after incubation with forskolin (FK) in the absence or in the presence of 100 μg/ml spilanthol (Spil + FK). AQP2 immunostaining was visualized in the xy apical confocal plan (upper panels) and in the xz confocal plan (lower panels). Compared to Ctr conditions, FK redistributed AQP2 staining to the apical plasma membrane. Spilanthol prevented the FK-induced effect on AQP2 membrane accumulation. Bar = 20 μm. Pictures are representative of at least three independent experiments giving the same results.</p