Journal: Military Medical Research

Article Title: USP18 exacerbates myocardial I/R injury by inhibiting Parkin mitophagy through the deubiquitinase PTEN-L

doi: 10.1016/j.mmr.2026.100004

Figure Lengend Snippet: Overexpression of USP18 in the heart exacerbates mitochondrial dysfunction, acute cardiac injury, and cardiac remodeling following I/R in mice. a TTC staining of heart tissue 24 h post-I/R in each group ( n= 5). Scale bar=0.5 cm. ⁎⁎⁎ P <0.001. b Mitochondrial DNA levels ( n= 6) and mitochondrial complexes I and II–III activity ( n= 5) 24 h post-I/R in each group. ⁎⁎ P <0.01, ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001. c Representative electron microscopy images of heart sections 24 h post-I/R. Quantitative analysis of mitochondrial volume density and the percent of mitochondria with cristae loss in each group ( n= 5). Scale bar=10 μm (top) and 6 μm (bottom). Red arrows indicate mitochondria with cristae loss. ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001. d Oxygen consumption rate (OCR) and quantitative statistical analysis of basal respiration, ATP-related respiration, maximal respiration, and spare respiratory capacity in mitochondria in the indicated groups ( n= 4). ⁎ P <0.05, ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001. e H&E staining, PSR staining, and quantitative statistical analysis of cell size and left ventricl e (LV) fibrotic area in AAV9-USP18-transfected mice at 4 weeks after I/R injury ( n= 5). Scale bar=1 mm (left), 50 μm (middle), and 100 μm (right). ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001. f Representative B-mode and M-mode echocardiographic images of LV from AAV9-USP18-transfected mice 4 weeks after I/R injury. g Cardiac function of AAV9-USP18-transfected mice after I/R injury at the indicated time points ( n= 6). ⁎⁎ P <0.01, ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001 vs . AAV9-NC, ns non-significant. USP18. Ubiquitin-specific protease 18; I/R. Ischemia/reperfusion; NC. Negative control; AAV9. Adeno-associated virus serotype 9; AAV9-USP18. Adeno-associated virus serotype 9 encoding USP18; TTC. 2,3,5-triphenyltetrazolium chloride; ATP. Adenosine triphosphate; H&E. Hematoxylin and eosin; PSR. picrosirius red; FCCP. Carbonyl cyanide p-trifluoromethoxyphenylhydrazone; LVIDd. Left ventricle internal diameter at diastole; LVISd. Left ventricle internal diameter at systole; LVEF. Left ventricle ejection fraction; LVFS. Left ventricle fractional shortening.

Article Snippet: To induce cardiac-specific USP18 overexpression, male C57BL/6 J mice received a single tail vein injection of adeno-associated virus serotype 9 (AAV9)-cardiac troponin T (cTnT)-USP18 or control AAV9-negative control [60–80 μl, (5.0–6.5)×1013 viral genome/ml, Vigene Bioscience, China] under 1.5%–2% isoflurane anesthesia.

Techniques: Over Expression, Staining, Activity Assay, Electron Microscopy, Transfection, Ubiquitin Proteomics, Negative Control, Virus

Journal: Military Medical Research

Article Title: USP18 exacerbates myocardial I/R injury by inhibiting Parkin mitophagy through the deubiquitinase PTEN-L

doi: 10.1016/j.mmr.2026.100004

Figure Lengend Snippet: Parkin knockdown counteracts the protection of USP18 deficiency in vivo. USP18-cKO mice were infected with AAV9-shParkin and subjected to I/R surgery. a Parkin protein levels in mouse hearts infected with AAV9-shParkin ( n= 4). b TTC staining of heart tissue 24 h post-I/R in each group ( n= 5). Scale bar=0.5 cm. c Serum levels of cTnI, CK-MB, and LDH in AAV9-shParkin-infected mice 4 h after I/R surgery ( n= 5). d DNA fragmentation and cleaved caspase-3 activity in heart tissue from AAV9-shParkin-infected mice 24 h after I/R injury ( n= 6). e Oxygen consumption rate (OCR) and quantitative statistical analysis of basal respiration, ATP-related respiration, maximal respiration, and spare respiratory capacity in mitochondria in the indicated groups ( n= 4). f Mitochondrial DNA ( n= 6) and complexes I and II–III activity ( n= 5) 24 h post-I/R in each group. g Representative electron microscopy images of heart sections 24 h post-I/R. The mitochondrial volume density and percent of mitochondria with cristae loss were measured in each group ( n= 5). Scale bar=10 μm (top) and 6 μm (bottom). h Protein levels of P62, ubiquitinated proteins (Ub), and LC3II in mitochondria from heart tissue 24 h after I/R injury ( n= 4). i H&E staining and quantitative statistical analysis of cell size ( n= 5) in USP18-cKO mice and AAV9-shParkin-infected mice 4 weeks after I/R injury. Scale bar=1 μm (top) and 50 μm (bottom). j Heart weight-to-tibia length ratio (HW/TL) ( n= 6) in each group. k Representative B-mode and M-mode echocardiographic images of the left ventricle from USP18-cKO mice and AAV9-shParkin-infected mice 4 weeks after I/R injury. l Cardiac function of USP18-cKO mice and AAV9-shParkin-infected mice 4 weeks after I/R injury ( n= 6). ⁎ P <0.05, ⁎⁎ P <0.01, ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001. USP18. Ubiquitin-specific protease 18; I/R. Ischemia/reperfusion; cTnI. Cardiac Troponin I; CK-MB. Creatine kinase-MB isoenzyme; LDH. Lactate dehydrogenase; NC. Negative control; AAV9. Adeno-associated virus serotype 9; AAV9-USP18. Adeno-associated virus serotype 9 encoding USP18; TTC. 2,3,5-triphenyltetrazolium chloride; ATP. Adenosine triphosphate; H&E. Hematoxylin and eosin; PSR. Picrosirius red; FCCP. Carbonyl cyanide p-trifluoromethoxyphenylhydrazone; LVIDd. Left ventricle internal diameter at diastole; LVISd. Left ventricle internal diameter at systole; LVEF. Left ventricle ejection fraction; LVFS. Left ventricle fractional shortening; HR. Heart rate.

Article Snippet: To induce cardiac-specific USP18 overexpression, male C57BL/6 J mice received a single tail vein injection of adeno-associated virus serotype 9 (AAV9)-cardiac troponin T (cTnT)-USP18 or control AAV9-negative control [60–80 μl, (5.0–6.5)×1013 viral genome/ml, Vigene Bioscience, China] under 1.5%–2% isoflurane anesthesia.

Techniques: Knockdown, In Vivo, Infection, Staining, Activity Assay, Electron Microscopy, Ubiquitin Proteomics, Negative Control, Virus

Journal: Military Medical Research

Article Title: USP18 exacerbates myocardial I/R injury by inhibiting Parkin mitophagy through the deubiquitinase PTEN-L

doi: 10.1016/j.mmr.2026.100004

Figure Lengend Snippet: USP18 inhibits mitophagy degradation and facilitates cardiac I/R injury through deubiquitinating and upregulating PTEN-L. a The protein levels of PTEN-L and PTEN in USP18-cKO mouse hearts 24 h after I/R injury ( n= 4). ⁎⁎⁎⁎ P <0.0001, ns non-significant. b The protein levels of PTEN-L and PTEN in AAV9-USP18-infected mouse hearts 24 h after I/R injury ( n= 4). ⁎⁎⁎ P <0.001, ⁎⁎⁎⁎ P <0.0001, ns non-significant. c Co-IP of USP18 and PTEN-L in NRVMs (left); NRVMs were transfected with HA-PTEN-L and Flag-USP18 (middle); Co-IP of Flag-USP18 and HA-PTEN-L in NRVMs (right). d Endogenous Co-IP of USP18 and PTEN-L in NRVMs subjected to H/R injury. e Endogenous Co-IP of USP18 and PTEN-L in hearts subjected to I/R injury. f PTEN-L ubiquitination (Ub) levels assessed by CO-IP in NRVMs subjected to H/R injury (top) and hearts subjected to I/R injury (bottom). g NRVMs were transfected with Ad-USP18 or USP18 siRNA or HA-PTEN-L and Myc-Ub and treated with MG132. Co-IP of Myc-Ub and HA-PTEN-L. h Schematic representations of t h e domains of PTEN-L involved in binding to USP18. Full-length PTEN-L or truncated PTEN-L was coexpressed with USP18 in HEK293T cells. Cells were subjected to immunoprecipitation with an anti-Myc antibody or an anti-HA antibody, followed by immunoblotting with the indicated antibodies. i Schematic representations of USP18 residues involved in binding to PTEN-L. Full-length USP18 or USP18 truncations were coexpressed with PTEN-L in HEK293T cells. Cells were subjected to immunoprecipitation with an anti-Myc antibody or an anti-HA antibody, followed by immunoblotting with the indicated antibodies. j Ub assay of PTEN-L in HEK293T cells cotransfected with Myc-USP18, Myc-USP18-mut, and Flag-PTEN-L and treated with 10 μmol/L MG132. k, l NRVMs were transfected with scRNA or USP18 siRNA ( k ), infected with Ad-NC or Ad-USP18 ( l ), and then treated with cycloheximide (CHX, 10 μmol/L) for the indicated time periods. Representative immunoblot analysis of PTEN-L protein levels in each group. ⁎⁎⁎⁎ P <0.0001 vs . scRNA or Ad-NC. USP18. Ubiquitin-specific protease 18; I/R. Ischemia/reperfusion; H/R. Hypoxia-reoxygenation; PTEN. Phosphatase and tensin homolog; PTEN-L. Phosphatase and tensin homolog-long; AAV9. Adeno-associated virus serotype 9; NC. Negative control.

Article Snippet: To induce cardiac-specific USP18 overexpression, male C57BL/6 J mice received a single tail vein injection of adeno-associated virus serotype 9 (AAV9)-cardiac troponin T (cTnT)-USP18 or control AAV9-negative control [60–80 μl, (5.0–6.5)×1013 viral genome/ml, Vigene Bioscience, China] under 1.5%–2% isoflurane anesthesia.

Techniques: Infection, Co-Immunoprecipitation Assay, Transfection, Ubiquitin Proteomics, Binding Assay, Immunoprecipitation, Western Blot, Virus, Negative Control