SLU-PP-322

SLU-PP-322 is a first-in-class synthetic small molecule pan-agonist of the estrogen-related receptor (ERR) family — specifically ERRalpha (ESRRA), ERRbeta (ESRRB), and ERRgamma (ESRRG). Unlike the classical oestrogen receptors (ERalpha, ERbeta), ERR receptors are constitutively active orphan nuclear receptors — they do not require ligand binding for basal transcriptional activity and have no confirmed endogenous ligand. SLU-PP-322 was identified through high-throughput screening and optimisation as a synthetic compound that activates all three ERR subtypes, driving the mitochondrial biogenesis, fatty acid oxidation, and oxidative metabolism gene expression programmes that ERRs normally regulate.

ERRalpha is the primary metabolic ERR isoform, expressed at highest levels in heart, skeletal muscle, kidney, and brown adipose tissue. ERRalpha co-activates with PGC-1alpha (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) — the master regulator of mitochondrial biogenesis — to drive transcription of genes encoding OXPHOS subunits (NDUFB5, SDHA, UQCRC2, ATP5A), fatty acid oxidation enzymes (HADHA, ACADM, HADHB, ACADVL), TCA cycle enzymes (IDH3A, OGDH, CS), and mitochondrial import machinery (TIMM proteins). SLU-PP-322 binding to ERRalpha's ligand-binding domain stabilises its active conformation, promoting PGC-1alpha and SRC coactivator recruitment and amplifying ERRalpha-driven transcription.

ERRgamma is the dominant ERR isoform in adult cardiac tissue and is essential for maintaining the oxidative metabolism programme that allows the adult heart to derive 60-70% of its energy from fatty acid oxidation. Heart failure is associated with metabolic regression toward foetal glucose-dominant metabolism — a shift partly attributable to decreased ERRgamma activity. SLU-PP-322's ERRgamma agonism makes it relevant for cardiac metabolism research examining whether ERR reactivation can restore oxidative metabolic capacity in cardiomyocyte failure models.

The published characterisation of SLU-PP-322 by Zuercher and colleagues positioned it as an "exercise mimetic" — a compound that activates molecular pathways engaged by physical training without the mechanical stimulus of exercise itself. This framing connects SLU-PP-322 research to AICAR (AMPK activator, another published exercise mimetic) and MOTS-c (exercise-induced mitokine): all three converge on overlapping mitochondrial biogenesis and fatty acid oxidation programmes through different upstream mechanisms.

SLU-PP-322 research uses ERR-responsive luciferase reporter assays (ERRE-driven firefly luciferase in stably transfected cells) as the primary pharmacological readout; quantitative PCR of ERR target genes (PGC-1alpha, TFAM, NRF1, PDK4, MCAD, LCAD) as the downstream transcriptional endpoint; mitochondrial biogenesis markers (mtDNA copy number by qPCR, MitoTracker staining, electron microscopy morphometry) as functional outputs; and Seahorse XF analysis (oxygen consumption rate, ATP production rate, maximal respiratory capacity) as the integrated metabolic endpoint.

MW: approximately 360 g/mol. CAS: 2381272-41-7. Solubility: DMSO at 100mM stock, dilute to less than 0.1% DMSO for cell work. Store lyophilised at -20°C, protected from light. For laboratory and analytical research purposes only.

For ERR target gene research: seed C2C12 myotubes (differentiated 5 days in DMEM + 2% horse serum) in 12-well plates. Treat with SLU-PP-322 (1-10uM in 0.1% DMSO) or vehicle for 24-48 hours. Measure: PGC-1alpha, TFAM, NRF1 (mitochondrial biogenesis markers); PDK4, MCAD, LCAD, HADHA (fatty acid oxidation markers); NDUFB5, SDHA (OXPHOS markers) — all by qRT-PCR with HPRT or 36B4 as housekeeping genes. Protein-level confirmation: PGC-1alpha and TFAM by Western blot. Functional metabolic endpoint: Seahorse XF assay measuring basal OCR, ATP-linked OCR, maximal OCR (after FCCP uncoupler), and spare respiratory capacity — SLU-PP-322 should increase all parameters reflecting enhanced mitochondrial biogenesis. ERR-reporter validation: co-transfect ERRE-luciferase (3xERRE-pGL3) with Renilla control into C2C12 cells; SLU-PP-322 should produce 3-10 fold luciferase induction. MW: approximately 360 g/mol. Store at -20°C. For laboratory and analytical research purposes only.