TRPC3 positively regulates reactive oxygen species driving maladaptive cardiac remodeling

Abstract

Reactive oxygen species (ROS) produced by NADPH oxidase 2 (Nox2) function as key mediators of mechanotransduction during both physiological adaptation to mechanical load and maladaptive remodeling of the heart. This is despite low levels of cardiac Nox2 expression. The mechanism underlying the transition from adaptation to maladaptation remains obscure, however. We demonstrate that transient receptor potential canonical 3 (TRPC3), a Ca2+-permeable channel, acts as a positive regulator of ROS (PRROS) in cardiomyocytes, and specifically regulates pressure overload-induced maladaptive cardiac remodeling in mice. TRPC3 physically interacts with Nox2 at specific C-terminal sites, thereby protecting Nox2 from proteasome-dependent degradation and amplifying Ca2+-dependent Nox2 activation through TRPC3-mediated background Ca2+ entry. Nox2 also stabilizes TRPC3 proteins to enhance TRPC3 channel activity. Expression of TRPC3 C-terminal polypeptide abolished TRPC3-regulated ROS production by disrupting TRPC3-Nox2 interaction, without affecting TRPC3-mediated Ca2+ influx. The novel TRPC3 function as a PRROS provides a mechanistic explanation for how diastolic Ca2+ influx specifically encodes signals to induce ROS-mediated maladaptive remodeling and offers new therapeutic possibilities.

TRPC3-Nox2 complex mediates doxorubicin-induced myocardial atrophy

“…We also found that voluntary exercise causes hypertrophy with preserved cardiac contractility by enhancing LV compliance and flexibility through destabilization of Nox2 (Figure 7, G-J, and Table 7). Taken together with our earlier observations made in a pressure-overloaded mouse heart model (20,27), our present findings, to our knowledge, provide a new concept that a TRPC3-Nox2 complex functions as a common major risk factor for chronic heart failure, driving pathological cardiac remodeling. Furthermore, they suggest that, by suppressing Nox2-mediated ROS production in cardiomyocytes, TRPC3 inhibition may be an effective strategy for reducing the risk of DOX-induced heart failure ( Figure 7K).…”

“…Therefore, we used a genetically encoded fluorescent sensor for hydrogen peroxide, Hyper, and confirmed that a DOX-induced increase in Hyper fluorescence intensity was suppressed by the treatment with siRNA for TRPC3 or Nox2 in H9c2 cardiac myoblasts (Supplemental Figure 2A). We previously reported that TRPC3 interacts with Nox2 via a TRPC3-specific C-terminal region -which protects Nox2 from proteasome-dependent degradation, leading to its stabilization -and that overexpression of a GFP-fused TRPC3-C terminal fragment peptide (C3-C-GFP) interfered with the interaction between Nox2 and TRPC3 without reducing TRPC3 channel activity (20) (Figure 3C). This prompted us to test the effect of C3-C-GFP on DOX-induced cardiomyocyte atrophy.…”

“…In particular, two TRP canonical (TRPC) subfamily members, TRPC3 and TRPC6, reportedly participate in the development of pathological hypertrophy caused by neurohumoral factors (22,23) and mechanical stress (24)(25)(26). Our recent studies using TRPC-KO mice revealed that TRPC3, but not TRPC6, functions as a positive regulator of ROS, leading to induction of mechanical stress-induced maladaptive fibrosis (15,20,27). TRPC3 interacts with Nox2 via TRPC3-specific C-terminal sites, thereby protecting Nox2 from proteasome-dependent degradation and amplifying Ca 2+ -dependent Nox2 activation through TRPC3-mediated background Ca 2+ entry (20).…”

“…Nox2 is activated by angiotensin II, endothelin-1, tumor necrosis factor-β, growth factors, and mechanical force, and Nox2-dependent ROS production reportedly mediates congestive heart failure in humans (18). Nox2 also participates in mechanochemical transduction in hearts through ROS production during LV diastolic filling (i.e., mechanical stretch of cardiomyocytes) (19,20). Notably, Nox2-deficient mice reportedly exhibit resistance to DOX-induced cardiac atrophy (13), but how Nox2 contributes to DOX-induced myocardial atrophy remains obscure.…”

“…Our recent studies using TRPC-KO mice revealed that TRPC3, but not TRPC6, functions as a positive regulator of ROS, leading to induction of mechanical stress-induced maladaptive fibrosis (15,20,27). TRPC3 interacts with Nox2 via TRPC3-specific C-terminal sites, thereby protecting Nox2 from proteasome-dependent degradation and amplifying Ca 2+ -dependent Nox2 activation through TRPC3-mediated background Ca 2+ entry (20). Nox2 also stabilizes TRPC3 proteins to enhance mechanical stress-induced background Ca 2+ entry into cardiomyocytes.…”