TY  - JOUR
A1  - Mrestani, Achmed
A1  - Pauli, Martin
A1  - Kollmannsberger, Philip
A1  - Repp, Felix
A1  - Kittel, Robert J.
A1  - Eilers, Jens
A1  - Doose, Sören
A1  - Sauer, Markus
A1  - Sirén, Anna-Leena
A1  - Heckmann, Manfred
A1  - Paul, Mila M.
T1  - Active zone compaction correlates with presynaptic homeostatic potentiation
JF  - Cell Reports
N2  - Neurotransmitter release is stabilized by homeostatic plasticity. Presynaptic homeostatic potentiation (PHP) operates on timescales ranging from minute- to life-long adaptations and likely involves reorganization of presynaptic active zones (AZs). At Drosophila melanogaster neuromuscular junctions, earlier work ascribed AZ enlargement by incorporating more Bruchpilot (Brp) scaffold protein a role in PHP. We use localization microscopy (direct stochastic optical reconstruction microscopy [dSTORM]) and hierarchical density-based spatial clustering of applications with noise (HDBSCAN) to study AZ plasticity during PHP at the synaptic mesoscale. We find compaction of individual AZs in acute philanthotoxin-induced and chronic genetically induced PHP but unchanged copy numbers of AZ proteins. Compaction even occurs at the level of Brp subclusters, which move toward AZ centers, and in Rab3 interacting molecule (RIM)-binding protein (RBP) subclusters. Furthermore, correlative confocal and dSTORM imaging reveals how AZ compaction in PHP translates into apparent increases in AZ area and Brp protein content, as implied earlier.
KW  - active zone
KW  - Bruchpilot
KW  - RIM-binding protein
KW  - compaction
KW  - homeostasis
KW  - presynaptic plasticity
KW  - super-resolution microscopy
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265497
VL  - 37
IS  - 1
ER  - 
TY  - JOUR
A1  - Tauscher, Sabine
A1  - Nakagawa, Hitoshi
A1  - Völker, Katharina
A1  - Werner, Franziska
A1  - Krebes, Lisa
A1  - Potapenko, Tamara
A1  - Doose, Sören
A1  - Birkenfeld, Andreas L.
A1  - Baba, Hideo A.
A1  - Kuhn, Michaela
T1  - β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice
JF  - Cardiovascular Diabetology
N2  - Background:
The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells.

Methods:
Mice with a floxed GC-A gene were bred to Rip-CreTG mice, thereby deleting GC-A selectively in β-cells (β GC-A KO). Weight gain, glucose tolerance, insulin sensitivity, and glucose-stimulated insulin secretion were monitored in normal diet (ND)- and high-fat diet (HFD)-fed mice. β-cell size and number were measured by immunofluorescence-based islet morphometry.

Results:
In vitro, the insulinotropic and proliferative actions of ANP were abolished in islets isolated from β GC-A KO mice. Concordantly, in vivo, infusion of BNP mildly enhanced baseline plasma insulin levels and glucose-induced insulin secretion in control mice. This effect of exogenous BNP was abolished in β GC-A KO mice, corroborating the efficient inactivation of the GC-A receptor in β-cells. Despite this under physiological, ND conditions, fasted and fed insulin levels, glucose-induced insulin secretion, glucose tolerance and β-cell morphology were similar in β GC-A KO mice and control littermates. However, HFD-fed β GC-A KO animals had accelerated glucose intolerance and diminished adaptative β-cell proliferation.

Conclusions:
Our studies of β GC-A KO mice demonstrate that the cardiac hormones ANP and BNP do not modulate β-cell's growth and secretory functions under physiological, normal dietary conditions. However, endogenous NP/GC-A signaling improves the initial adaptative response of β-cells to HFD-induced obesity. Impaired β-cell NP/GC-A signaling in obese individuals might contribute to the development of type 2 diabetes.
KW  - cylic GMP
KW  - guanylyl cyclase-A
KW  - insulin
KW  - natriuretic peptides
KW  - obesity
KW  - β-cells
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176322
VL  - 17
IS  - 103
ER  -