GRK2 (G protein-coupled receptor kinase 2 / ADRBK1)

GRK2 is a ubiquitous cytosolic serine/threonine kinase that phosphorylates agonist-occupied G protein-coupled receptors (GPCRs) — the master switch of receptor desensitization and internalization. In the aging context, GRK2 is most critical as the molecular executor of β-adrenergic receptor (β-AR) desensitization in the aging heart: it is upregulated in human heart failure and in aged myocardium, directly contributing to blunted cAMP signaling, reduced inotropic reserve, and diastolic dysfunction. GRK2 also has kinase-independent scaffolding roles including insulin receptor regulation (metabolic aging) and mitochondrial pro-death signaling. Pharmacological GRK2 inhibition — via paroxetine repurposing, gallein (Gβγ inhibitor), or the peptide gene therapy βARKct — is an active therapeutic strategy in heart failure preclinical research, but has not been tested in an aging-specific human trial as of 2026.

Identity

Field	Value
UniProt	P25098 (GRK2_HUMAN) — Swiss-Prot reviewed
NCBI Gene	156
HGNC	HGNC:289
Ensembl	ENSG00000173020
Gene symbol	GRK2 (primary); synonyms ADRBK1, BARK, BARK1
Protein name	G protein-coupled receptor kinase 2; alt: Beta-adrenergic receptor kinase 1 (Beta-ARK-1)
Length	689 amino acids (canonical human isoform)
Mouse ortholog	Grk2 (MGI symbol; synonym Adrbk1); UniProt Q99MK8
GenAge entry	null — GRK2 / ADRBK1 is not in the GenAge curated human aging gene set as of 2026-06-14

Domain architecture

GRK2 has a three-domain architecture that underlies its dual kinase/scaffolding roles ¹:

Domain	Residues (human)	Function
RGS homology (RH) domain	54–175	Binds activated Gαq — sequesters and inhibits Gαq independently of kinase activity; also binds clathrin heavy chain
Protein kinase (AGC family)	191–453	Catalytic Ser/Thr kinase domain; phosphorylates agonist-occupied GPCR intracellular tails
AGC-kinase C-terminal	454–521	Regulatory lobe; required for full kinase activation
Pleckstrin homology (PH) domain	558–652	Binds Gβγ subunits (membrane recruitment upon GPCR activation) and phosphoinositides (PI(4,5)P₂); Gβγ-PH interaction is required for translocation to the plasma membrane and efficient substrate phosphorylation

The PH-Gβγ interaction is mechanistically central: Gβγ released from activated GPCRs recruits GRK2 from the cytosol to the plasma membrane, where it then phosphorylates the same activated receptor. This constitutes a feedforward desensitization loop — the receptor’s own activation signal triggers its own kinase inhibitor.

Desensitization mechanism: β-AR → GRK2 → β-arrestin loop

The canonical GRK2-dependent desensitization cycle for β-adrenergic receptors (β1-AR and β2-AR):

Agonist (NE, Epi) binds β-AR → Gαs + Gβγ released; Gαs activates adenylyl cyclase (AC); Gβγ recruits GRK2 to the membrane.
GRK2 phosphorylates the agonist-occupied β-AR on Ser/Thr residues of the third intracellular loop (β2-AR) and C-tail (both subtypes).
β-Arrestin-1/2 binds phosphorylated receptor → sterically uncouples from Gαs → terminates cAMP synthesis.
Receptor internalization — β-arrestin scaffolds clathrin + AP-2 → endocytosis.
Receptor fate — β2-AR: recycled to membrane (short-term resensitization); β1-AR: sorted to lysosomes (chronic downregulation) ².

GRK2 is the rate-limiting step for this cycle; elevated GRK2 expression (as in the failing or aging heart) shifts the equilibrium toward faster desensitization and faster β1-AR lysosomal routing, impairing recovery of surface receptor density.

For the downstream cAMP/PKA cascade that GRK2 dampens, see camp-signaling. For the catecholamine ligands (NE, Epi) that trigger this cycle, see catecholamines.

GRK2 upregulation in heart failure and aging

Human heart failure

The foundational finding is a landmark 1993 Circulation paper: in explanted failing human hearts (dilated cardiomyopathy and ischemic cardiomyopathy), both betaARK1 (GRK2) mRNA and protein levels were elevated ~3-fold relative to non-failing donor hearts, while β1-AR density was reduced ~50% ³. This established GRK2 upregulation as a hallmark of the failing human myocardium and provided the molecular mechanism for the long-known clinical observation that β-adrenergic responsiveness is severely blunted in heart failure.

A comprehensive 2018 review documents the paired changes in heart failure and aging: SNS hyperactivity → chronic catecholamine stimulation → compensatory GRK2 upregulation → further receptor downregulation → reduced AC activation → reduced cAMP amplitude per unit agonist ². This creates a vicious cycle: the compensatory tachycardia and inotropism that the failing heart needs is progressively eroded by desensitization of its own receptors.

Change in HF/aging myocardium	Direction	Effect
β1-AR surface density	↓ ~50% (HF)	Less receptor available for catecholamines
GRK2 protein expression	↑ ~2–3× (HF); elevated in aged vascular tissue ⁴	Faster receptor desensitization per agonist exposure
Gαi protein	↑	Inhibits AC directly, compounding cAMP deficit
AC5/AC6 expression	↓ (cardiac)	Lower maximal cAMP production capacity
PDE4D	↑ activity	Faster cAMP hydrolysis before full PKA activation

Aging-specific evidence

In aged rat aorta, GRK-2 (cytoplasmic and membrane-associated) and GRK-3 expression increase significantly with advancing age relative to young adults ⁴. Age-related β-adrenergic vasorelaxation impairment can be rescued by reducing GRK2 expression in vascular smooth muscle, confirming causal directionality in that tissue ⁵. In the context of the aging heart, loss of S-nitrosylation-mediated dynamic GRK2 regulation (nitric oxide normally dampens GRK2 activity; this regulatory capacity is lost with age) is sufficient to cause cardiac remodeling and dysfunction in mice ⁶.

A 2022 study in the coronary microcirculation demonstrated that age-associated decline in β1-AR expression and concurrent GRK2 upregulation in coronary arterioles was rescued by stromal vascular fraction cell therapy, linking GRK2 dysregulation directly to age-related microvascular dysfunction ⁷.

The clinical consequence is the well-documented decline in maximum inotropic and chronotropic reserve with aging — a loss of “cardiac stress response” that contributes to reduced exercise capacity and HFpEF susceptibility. See heart-failure for the full cardiac aging phenotype page; see cardiovascular-aging for the broader cardiovascular aging context.

Extrapolation table:

Dimension	Status
GRK2 upregulation in human heart failure?	yes — Ungerer 1993 (Circulation); confirmed in multiple subsequent studies
GRK2 upregulation in normal human cardiac aging (non-failing)?	partial — demonstrated in aged rodent aorta and rat hepatocyte (Schutzer 2001, 2005); human aging-specific cardiac data limited
GRK2 inhibition rescues cardiac function in HF models?	yes — rodent and porcine models (βARKct, paroxetine); not tested in human aging RCT

Kinase-independent and extra-cardiac roles in aging

GRK2 and insulin signaling / metabolic aging

GRK2 acts as a negative regulator of insulin signaling through kinase-independent scaffolding: GRK2 physically binds the insulin receptor substrate (IRS-1) and sequesters it from downstream PI3K-Akt signaling, impairing insulin sensitivity ⁸. GRK2 is elevated in adipose tissue in insulin resistance and obesity, and myeloid-specific GRK2 reduction protects against diet-induced adipose-liver crosstalk dysfunction and hepatic insulin resistance in mice ⁹. This positions GRK2 as a potential molecular link between the chronic adrenergic overdrive of aging and age-related metabolic dysfunction (insulin resistance, impaired adipose lipolysis).

Note: a key early paper in this area (Garcia-Guerra et al. 2010, Diabetes) was retracted in 2020; claims derived solely from that study should not be cited. The myeloid GRK2 metabolic role (Vila-Bedmar 2020) stands independently.

Mitochondrial GRK2 and pro-death signaling

Following ischemic stress or oxidative injury, GRK2 undergoes ERK-dependent phosphorylation at Ser670, which triggers HSP90-mediated translocation of GRK2 to the inner mitochondrial membrane ¹⁰. Mitochondrial GRK2 promotes permeability transition pore opening, cytochrome c release, and cell death — functioning as a “pro-death kinase” rather than a receptor desensitizer at this location. This is relevant to aging because oxidative stress levels are chronically elevated in aged cardiomyocytes, potentially sustaining mitochondrial GRK2 signaling and contributing to cardiomyocyte apoptosis in the aging heart. See mitochondrial-dysfunction for the broader mitochondrial aging context.

GRK2 in non-cardiac aging contexts

Renal dopaminergic signaling: GRK2-mediated D1 receptor hyperphosphorylation in renal proximal tubule cells, driven by aging-related oxidative stress, impairs natriuresis and contributes to age-associated hypertension ¹¹.
Lymphocyte adrenergic signaling: GRK2 levels in peripheral blood lymphocytes correlate with cardiac sympathetic activity and have been proposed as a non-invasive biomarker of myocardial β-AR function in heart failure ¹².
GRK2 as biomarker of sympathetic overdrive: Lymphocyte GRK2 mirrors myocardial GRK2 dynamics under sympathetic stimulation, offering a liquid-biopsy approach to assessing adrenergic desensitization ¹².

Druggability and therapeutic strategies

Aging-context druggability tier: 2 (high-quality probe; no approved drug for aging or HF indication via GRK2 mechanism).

Rationale: multiple potent and selective GRK2 inhibitors exist in preclinical stages; paroxetine is an FDA-approved drug with validated GRK2 inhibitory activity used in HF model studies; βARKct has been tested in large-animal HF models (porcine). However, no GRK2-targeted therapy is approved for heart failure or any aging indication, and no aging-specific human RCT of GRK2 inhibition has been conducted. Clinical translation is advanced relative to undruggable targets (tier 4) or prediction-only targets (tier 3), but not at the approved-drug tier 1 level. Compare camp-signaling (druggability tier 1 via AC5 inhibition / PDE inhibitors).

βARKct — Gβγ-sequestering peptide gene therapy

The βARKct construct (C-terminal fragment of GRK2 containing the PH domain, amino acids ~495–689) sequesters Gβγ rather than inhibiting GRK2’s kinase activity directly — the PH domain outcompetes endogenous GRK2 for Gβγ binding, preventing GRK2 membrane recruitment and receptor phosphorylation ¹³. Delivered via AAV6:

AAV6-βARKct in a rat pressure-overload HF model: significantly improved cardiac contractility and reversed LV remodeling; normalized catecholamine spillover ¹⁴.
AAV6-βARKct in a porcine post-MI HF model: “virtually normalized” the catecholaminergic axis and improved LV hemodynamics; effects were sustained over long-term follow-up ¹⁵.
gap/needs-human-replication — βARKct gene therapy has not been tested in human clinical trials as of 2026.

Paroxetine — repurposed SSRI with GRK2 inhibitory activity

Paroxetine (SSRI antidepressant; FDA-approved for depression/anxiety) was discovered to inhibit GRK2 at its kinase active site with IC₅₀ in the low-micromolar range — a serendipitous finding given paroxetine’s known clinical profile. In a mouse post-MI heart failure model, paroxetine treatment (at cardiac-GRK2-relevant doses, distinct from antidepressant concentrations) significantly improved LV function and structure — results reported as “markedly greater than those of β-blocker therapy” in the same model ¹⁶.

However, a large retrospective cohort study of paroxetine in human heart failure patients (n=77 paroxetine-treated vs 231 matched controls; MIMIC-IV database, 2008–2019) found no significant reduction in 28-day mortality (adjusted HR 1.00, 95% CI 0.42–2.62) ¹⁷. This negative observational finding does not constitute a null trial — confounding by indication, dose heterogeneity, and short follow-up all limit interpretation — but it does temper enthusiasm for paroxetine repurposing in HF pending prospective data.

gap/needs-human-replication — no prospective RCT of paroxetine for GRK2 inhibition in heart failure or cardiac aging has been conducted.

Gallein — small-molecule Gβγ inhibitor

Gallein and M119 are small-molecule Gβγ inhibitors that share the mechanism of βARKct (preventing GRK2 membrane recruitment by blocking Gβγ) but are orally bioavailable small molecules. Gallein has been shown to reduce cardiac hypertrophy and improve hemodynamics in HF models. Like βARKct, these agents have not advanced to human cardiac aging trials. The 2026 Roy and Koch review identifies both GRK2 kinase inhibitors and Gβγ blockers as active development priorities ¹⁸.

miR-181a — endogenous GRK2 repressor

miR-181a directly targets the GRK2 3’UTR and suppresses GRK2 at both mRNA and protein levels; overexpression of miR-181a in cardiomyocytes reduced hypertrophy, oxidative stress, and improved cell survival under hypoxic conditions ¹⁹. This identifies a potential RNA therapeutic strategy for GRK2 inhibition in heart failure.

Exercise training as physiological GRK2 modulator

Chronic endurance exercise training reduces cardiac GRK2 levels, restores β-AR surface density, and improves adenylyl cyclase activation in aged and failing hearts — providing a mechanistic basis for exercise’s cardiac benefits in aging ²⁰. Exercise is the only intervention with established human functional evidence for improving adrenergic responsiveness in the aging/HF context, though direct GRK2 protein quantification in human myocardium after exercise training has not been reported. gap/needs-human-replication

Hallmark connections

Hallmark	Mechanistic link
altered-intercellular-communication	GRK2 upregulation → β-AR desensitization → blunted catecholamine response → impaired neuroendocrine-cardiac crosstalk; lymphocyte GRK2 as biomarker of cardiac sympathetic tone
deregulated-nutrient-sensing	GRK2 scaffolding inhibits IRS-1/PI3K-Akt insulin signaling; myeloid GRK2 modulates adipose-liver metabolic crosstalk ⁹
mitochondrial-dysfunction	Mitochondrial GRK2 translocation (ERK/HSP90-dependent) promotes permeability transition pore opening and cardiomyocyte apoptosis after ischemic and oxidative stress ¹⁰

Key interactors

Gβγ — recruits GRK2 from cytosol to plasma membrane (PH domain interaction); therapeutic target of βARKct and gallein
Gαq — bound and inhibited by the RH domain of GRK2 (kinase-independent)
β-Arrestin-1/2 — the downstream effectors that bind GRK2-phosphorylated GPCRs and execute desensitization/internalization
HSP90 — chaperones GRK2 to mitochondria after Ser670 phosphorylation by ERK under ischemic stress ¹⁰
Akt (PKB) — GRK2 phosphorylates Akt at Ser473 in some contexts, modulating insulin signaling; bidirectional regulation

Limitations and gaps

gap/needs-human-replication — GRK2 inhibition specifically for cardiac aging (not post-MI HF) has no human clinical trial data. All inhibitor evidence is from rodent or porcine HF models.
gap/needs-human-replication — The elevation of GRK2 in normally aged (non-failing) human myocardium has not been directly demonstrated from human tissue biopsies; most human data comes from explanted HF hearts.
gap/needs-replication — The paroxetine retrospective cohort study (Xu 2022, n=77) is underpowered and observational; the positive preclinical signal (Schumacher 2015, mouse MI model) has not been confirmed in a prospective human trial.
gap/no-mechanism — The mechanism by which GRK2 is upregulated in aging — whether from chronic catecholamine exposure, transcriptional induction by NF-κB or other inflammatory signals, loss of S-nitrosylation-mediated suppression, or post-translational stabilization — is not definitively established in human aging (as opposed to experimentally induced HF models).
gap/needs-canonical-id — GenAge ID is null; GRK2/ADRBK1 does not appear in the GenAge human aging gene database (confirmed search 2026-06-14). If aging-specific GenAge inclusion occurs in future updates, revisit.
gap/dose-response-unclear — For paroxetine repurposing, the GRK2-inhibitory dose range and the antidepressant/SERT-inhibitory dose range in humans overlap; defining a cardiac-selective dosing window is unsolved.

Footnotes

UniProt P25098 (GRK2_HUMAN), Swiss-Prot reviewed entry, accessed 2026-06-14 · source for domain annotations (RH 54–175, kinase 191–453, AGC-CT 454–521, PH 558–652), protein length 689 aa, gene names (GRK2/ADRBK1/BARK/BARK1), subcellular locations (cytoplasm, cell membrane, cilium, postsynapse, presynapse) ↩
doi:10.3389/fphar.2018.00904 · PMID:30147654 · de Lucia C, Eguchi A, Koch WJ · “New Insights in Cardiac β-Adrenergic Signaling During Heart Failure and Aging” · Front Pharmacol 9:904 · 2018 · review · human + rodent models · comprehensive synthesis of β-AR/GRK2 changes in HF and aging; discusses β-blocker and exercise mitigation of GRK2-driven desensitization; Koch laboratory perspective ↩ ↩²
doi:10.1161/01.cir.87.2.454 · PMID:8381058 · Ungerer M, Böhm M, Elce JS, Erdmann E, Lohse MJ · “Altered expression of beta-adrenergic receptor kinase and beta 1-adrenergic receptors in the failing human heart” · Circulation 87(2):454–463 · 1993 · observational · n=18 HF patients (8 DCM + 10 ICM) vs 6 non-failing donor hearts · βARK mRNA elevated almost threefold in both DCM and ICM vs non-failing; βARK enzymatic activity also elevated; β1-AR density reduced from 73±6.1 to 35±6.7 fmol/mg protein (~52%, reported as ~50%) in failing myocardium; β2-AR density and β2-AR mRNA unchanged; foundational human heart failure GRK2 paper ↩
doi:10.1152/ajpregu.2001.280.3.R897 · PMID:11171671 · Schutzer WE, Reed JF, Bliziotes M, Mader SL · “Upregulation of G protein-linked receptor kinases with advancing age in rat aorta” · Am J Physiol Regul Integr Comp Physiol 280(3):R897–R903 · 2001 · observational · model: Fischer 344 rat aorta, young vs aged; quantifies GRK-2 and GRK-3 protein increase in aged vascular tissue; supports GRK2 upregulation as an aging-related change in the vasculature ↩ ↩²
doi:10.1016/j.vph.2011.09.001 · PMID:21951806 · Schutzer WE, Xue H, Reed J et al. · “Age-related β-adrenergic receptor-mediated vasorelaxation is changed by altering G protein receptor kinase 2 expression” · Vascular Pharmacology 55(1–3):178–183 · 2011 · in-vitro + ex-vivo · model: rat carotid artery smooth muscle; GRK2 overexpression impairs β-AR vasorelaxation; causally confirms GRK2 as the mediator of age-related vascular adrenergic blunting ↩
doi:10.1152/ajpheart.00094.2020 · PMID:32216616 · Lieu M, Traynham CJ, de Lucia C et al. · “Loss of dynamic regulation of G protein-coupled receptor kinase 2 by nitric oxide leads to cardiovascular dysfunction with aging” · Am J Physiol Heart Circ Physiol 318(5):H1162–H1175 · 2020 · in-vivo (mouse) · model: knock-in mice lacking GRK2 S-nitrosylation site; chronic unregulated GRK2 activity sufficient to cause cardiac remodeling and dysfunction by 12 months; establishes loss of NO-GRK2 regulation as aging mechanism ↩
doi:10.1007/s11357-021-00455-6 · PMID:34608562 · Rowe G, Tracy E, Beare JE, LeBlanc AJ · “Cell therapy rescues aging-induced beta-1 adrenergic receptor and GRK2 dysfunction in the coronary microcirculation” · GeroScience 44(1):329–348 · 2022 · in-vivo (rodent) · model: aged Fischer 344 × Brown Norway rats; SVF cell therapy restores β1-AR expression and GRK2 phosphorylation balance in aged coronary arterioles; demonstrates GRK2 dysregulation as mechanism of age-related coronary microvascular dysfunction ↩
doi:10.3109/13813455.2015.1107589 · PMID:26643283 · Lucas E, Cruces-Sande M, Briones AM et al. (Mayor F Jr, Murga C, Vila-Bedmar R) · “Molecular physiopathology of obesity-related diseases: multi-organ integration by GRK2” · Arch Physiol Biochem 121(5):166–178 · 2015 · review · examines GRK2 as a multi-organ integrator in obesity/metabolic disease; covers GRK2-IRS-1 scaffolding mechanism impairing insulin signaling; proposes GRK2 as link between adrenergic overdrive and insulin resistance across tissues ↩
doi:10.1007/s00018-019-03442-5 · PMID:31927610 · Vila-Bedmar R, Cruces-Sande M, Arcones AC et al. · “GRK2 levels in myeloid cells modulate adipose-liver crosstalk in high fat diet-induced obesity” · Cell Mol Life Sci 77(23):4957–4976 · 2020 · in-vivo (mouse) · model: myeloid-specific GRK2 hemizygous knockout mice; HFD challenge; myeloid GRK2 reduction prevents glucose intolerance, attenuates macrophage pro-inflammatory responses, protects hepatic and adipose insulin signaling; links GRK2 to metabolic aging via immune-metabolic tissue crosstalk ↩ ↩²
doi:10.1161/CIRCRESAHA.112.300754 · PMID:23467820 · Chen M, Sato PY, Chuprun JK et al. (Koch WJ corresponding) · “Prodeath signaling of G protein-coupled receptor kinase 2 in cardiac myocytes after ischemic stress occurs via extracellular signal-regulated kinase-dependent heat shock protein 90-mediated mitochondrial targeting” · Circ Res 112(8):1121–1134 · 2013 · in-vitro + in-vivo (mouse) · model: neonatal rat ventricular myocytes (NRVMs) + H9c2 cells + HEK293 cells; 8–10-week-old C57BL/6 mouse I/R model (30 min ischemia + 30 min reperfusion); GRK2-cardiac-transgenic and βARKct-transgenic mice · ERK → GRK2 Ser670 phosphorylation → HSP90-GRK2 complex → mitochondrial translocation → increased mPTP Ca²⁺ sensitivity → cell death; βARKct expression prevents stress-induced mitochondrial GRK2 translocation and is cardioprotective; establishes mitochondrial GRK2 as a pro-death kinase in cardiac ischemia ↩ ↩² ↩³
doi:10.1152/ajprenal.00111.2006 · PMID:16757732 · Fardoun RZ, Asghar M, Lokhandwala M · “Role of oxidative stress in defective renal dopamine D1 receptor-G protein coupling and function in old Fischer 344 rats” · Am J Physiol Renal Physiol 291(5):F945–F951 · 2006 · in-vivo (rat) · model: aged Fischer 344 rats vs young; oxidative stress increases renal GRK-2 abundance → D1 receptor hyperphosphorylation → impaired natriuresis; antioxidant tempol normalizes; mechanism for age-associated hypertension via renal GRK2 ↩
doi:10.3390/cells10020457 · PMID:33669936 · Bencivenga L, Palaia ME, Sepe I et al. (Cannavo A co-author) · “Why Do We Not Assess Sympathetic Nervous System Activity in Heart Failure Management: Might GRK2 Serve as a New Biomarker?” · Cells 10(2):457 · 2021 · review · proposes lymphocyte GRK2 as a non-invasive biomarker of cardiac sympathetic activity and myocardial β-AR function in HF; reviews evidence for GRK2 as prognostic biomarker ↩ ↩²
doi:10.1038/sj.gt.3301995 · PMID:12883532 · Li Z, Laugwitz K-L, Pinkernell K et al. (Ungerer M corresponding) · “Effects of two Gbetagamma-binding proteins — N-terminally truncated phosducin and beta-adrenergic receptor kinase C terminus (betaARKct) — in heart failure” · Gene Ther 10(19):1672–1679 · 2003 · in-vitro + in-vivo · establishes that βARKct effects may be primarily via Gβγ sequestration rather than β-AR resensitization; mechanistic clarification of the βARKct mode of action ↩
doi:10.1161/CIRCULATIONAHA.108.803999 · PMID:19103992 · Rengo G, Lymperopoulos A, Zincarelli C et al. (Koch WJ corresponding) · “Myocardial adeno-associated virus serotype 6-betaARKct gene therapy improves cardiac function and normalizes the neurohormonal axis in chronic heart failure” · Circulation 119(1):89–98 · 2009 · in-vivo (rat) · model: rat pressure-overload HF; AAV6-βARKct long-term delivery; improved contractility, reversed LV remodeling, normalized catecholamines and aldosterone; βARKct monotherapy effective; establishes rodent proof-of-concept for βARKct gene therapy ↩
doi:10.1093/eurheartj/ehr447 · PMID:22261894 · Raake PW, Schlegel P, Ksienzyk J et al. (Most P, Müller OJ corresponding) · “AAV6.βARKct cardiac gene therapy ameliorates cardiac function and normalizes the catecholaminergic axis in a clinically relevant large animal heart failure model” · Eur Heart J 34(19):1437–1447 · 2013 · in-vivo (porcine) · model: porcine post-MI HF; AAV6-βARKct; LV haemodynamics significantly improved; neurohormonal axis virtually normalized; large-animal translational validation for βARKct ↩
doi:10.1126/scitranslmed.aaa0154 · PMID:25739765 · PMC:PMC4768806 · Schumacher SM, Gao E, Zhu W et al. (Koch WJ, Tesmer JJG corresponding) · “Paroxetine-mediated GRK2 inhibition reverses cardiac dysfunction and remodeling after myocardial infarction” · Sci Transl Med 7(277):277ra31 · 2015 · in-vivo (mouse) · model: C57BL/6 male mice, permanent LAD ligation MI model; n=9–14/group; paroxetine 5 mg/kg/day via subcutaneous miniosmotic pump started 2 weeks post-MI; serum levels 27–192 ng/mL (clinically comparable) · paroxetine reversed LV dysfunction (LVEF ~30% absolute increase above vehicle) and reduced GRK2 protein; “The beneficial effects of paroxetine were markedly greater than those of β-blocker therapy” (metoprolol); metoprolol stabilized but did not reverse LV dysfunction and did not reduce fetal gene program, whereas paroxetine alone did; establishes paroxetine as a repurposed GRK2 inhibitor with cardiac functional benefit superior to metoprolol in this model ↩
doi:10.3389/fcvm.2021.794584 · PMID:35155607 · Xu H, Meng L, Long H et al. · “Paroxetine and Mortality in Heart Failure: A Retrospective Cohort Study” · Front Cardiovasc Med 8:794584 · 2022 · observational (retrospective cohort) · n=77 paroxetine-treated HF patients + 231 matched controls; MIMIC-IV database 2008–2019; 28-day mortality: adjusted HR 1.00 (95% CI 0.42–2.62); null result; caution: small n, short follow-up, confounding by indication; does not refute the preclinical signal but should temper translation optimism ↩
doi:10.1016/j.molpha.2025.100095 · PMID:41494456 · Roy R, Koch WJ · “GRK2 and GRK5 — The 2 critical kinases in cardiac pathophysiology” · Mol Pharmacol · 2026 · review · comprehensive 2026 review of GRK2 and GRK5 in heart failure; covers inhibitor landscape (paroxetine, M119, gallein), cell-type specificity, and therapeutic directions; Koch laboratory perspective ↩
doi:10.3389/fcvm.2026.1821660 · PMID:42099781 · Cho H, Lieu M, Gao E et al. (Koch WJ corresponding) · “miR-181a post-transcriptionally targets GRK2 to limit maladaptive signaling in cardiomyocytes” · Front Cardiovasc Med · 2026 · in-vitro + in-vivo · miR-181a directly targets GRK2 3’UTR → reduced GRK2 protein → reduced hypertrophy, oxidative stress, improved cAMP signaling under hypoxia; identifies miR-181a as endogenous GRK2 repressor and potential therapeutic modality ↩
doi:10.3389/fphys.2013.00348 · PMID:24348425 · Leosco D, Parisi V, Femminella GD et al. · “Effects of exercise training on cardiovascular adrenergic system” · Front Physiol 4:348 · 2013 · review · human + animal models · exercise training reduces cardiac GRK2 → restores β-AR density and AC activation → improves cardiac adrenergic response; mechanism for exercise-induced adrenergic improvement in HF and aging ↩

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