Journal: bioRxiv

Article Title: Ubiquitin Ligase ITCH Regulates Life Cycle of SARS-CoV-2 Virus

doi: 10.1101/2024.12.04.624804

Figure Lengend Snippet: (A) Culture medium from vT2-WT and vT2-ITCH-KO cells expressing HA-tagged ubiquitin (Ub) and Flag-2×Strep tagged E was harvested for Strep AP. A decrease of the extracellular E protein induced by ITCH ablation was visualized by immunoblot (left) and dot blot analysis (right). (B) Lysates from HEK293 cells expressing Flag-tagged E with ITCH or ITCH-CS were subjected to Flag IP, followed by immunoblotting for autophagosome cargo receptors. E specifically precipitated p62 and ITCH promoted their interaction. (C-E) HEK293 cells were transfected with Flag-tagged E with ITCH or ITCH-CS. 24 h later, cells were analyzed by immunofluorescence with Flag, ITCH and p62 or LC3B or LAMP1 antibodies. ITCH enhanced the colocalization between E and p62 (C) or LC3B (D), while no change in the colocalization between E and LAMP1 (E) was noted. Scale bar, 10 μm. (F) Culture media and denatured lysates from control (CTRL) and p62 knock down (#1, #2) HEK293 cells expressing HA-tagged ubiquitin (Ub), Flag-tagged E were subjected to Flag IP (with incorporation of a washing step with urea before elution for culture media samples), followed by immunoblotting or dot blot analysis. p62 depletion resulted in the accumulation of intracellular E (both unmodified and ubiquitinated), while decreasing the level of extracellular E (n=3). (G, H) vT2-WT and vT2-ITCH-KO cells infected with SARS-CoV-2 at 1 MOI for 10 h were subjected to immunofluorescence analysis with E and p62 or LC3B antibodies. ITCH-ablation decreased the colocalization between E and p62 (G) or LC3B (H). Scale bar, 10 μm. (I) A model of the function of ITCH in promoting autophagosome-mediated SARS-CoV-2 virion egress. ITCH-dependent ubiquitin modification enhances E binding with S and M binding with non-ubiquitinated E, resulting in the increase in virion formation and p62-dependent autophagosome targeting for release.

Article Snippet: The following primary antibodies were used: Flag (Sigma, F1804); Flag (Sigma, F3165); Flag (Cell Signaling Technology, 14793S); GAPDH (Invitrogen, MA5-27912); β-tubulin (Cell Signaling Technology, 2128S);s (BioLegend, 688102); Strep (Invitrogen, MA5-17283); CBD (New England BioLabs, E8034S); ubiquitin (Cell Signaling Technology, 58395S); K63-linkage-specific antibody (Enzo Life Sciences, BML-PW0600-0100); K48-linkage-specific antibody (Cell Signaling Technology, 8081S); Spike (Proteintech, 28867-1-AP); M (Proteintech, 28882-1-AP); E (Proteintech, 28904-1-AP); ITCH (Santa Cruz, sc-28367); ITCH (Novus Biologicals, NB100-68142); p62 (Cell Signaling Technology, 88588S and 7695S); GM130 (Proteintech, 11308-1-AP); LAMP1 (Cell Signaling Technology, 9091S); OPTN (Cayman Chemical, 100002); LC3 (Proteintech,14600-1-AP); LC3B (Cell Signaling Technology, 3868S); SARS-CoV-2 Membrane protein (Cell Signaling Technology, 15333S); SARS-CoV-2 Envelope protein (Cell Signaling Technology, 74698S); furin (Proteintech, 18413-1-AP); Cathepsin L (Proteintech, 10938-1-AP); NDP52 (Proteintech, 12229-1-AP); NBR1 (Proteintech, 16004-1-AP); FAM134B (Proteintech, 21537-1-AP); RTN3 (Proteintech, 12055-2-AP) and NIX (Proteintech, 12986-1-AP).

Techniques: Expressing, Western Blot, Dot Blot, Transfection, Immunofluorescence, Control, Knockdown, Infection, Modification, Binding Assay

Journal: The Journal of biological chemistry

Article Title: Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

doi: 10.1074/jbc.272.16.10882

Figure Lengend Snippet: FIG. 4. Effects of estradiol on cyclin protein expression. The experimental design was described in Fig. 2. Representative Western blots are shown for G1 phase cyclins (D1, D3, E) (A) and S/G2M phase cyclins (A, B1) (B). Controls for cyclin E are as described in Fig. 2.

Article Snippet: Antibodies used were rabbit polyclonal antisera to human cyclin D1 (29), human cyclin E (C-19; Santa Cruz Biotechnology), and human Cdk2 (M2; Santa Cruz Biotechnology).

Techniques: Expressing, Western Blot

Journal: The Journal of biological chemistry

Article Title: Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

doi: 10.1074/jbc.272.16.10882

Figure Lengend Snippet: FIG. 5. Estrogen induction of cyclin D1 and cyclin D3 mRNA expression. MCF-7 cells were pretreated with 10 nM ICI 182780 for 48 h and then treated with 100 nM E2 or vehicle (control) at time 0. At intervals thereafter, total cellular RNA was harvested. A, representative North- ern blots are shown for cyclin D1 and D3 mRNA from estradiol-treated and control cells. Arrows indicate the 4.5- and 1.5-kb cyclin D1 transcripts. B, graphical pres- entation of temporal changes in mRNA (open symbols) and protein (solid symbols, mean of two experiments) for cyclin D1 (left) and cyclin D3 (right).

Article Snippet: Antibodies used were rabbit polyclonal antisera to human cyclin D1 (29), human cyclin E (C-19; Santa Cruz Biotechnology), and human Cdk2 (M2; Santa Cruz Biotechnology).

Techniques: Expressing, Control

Journal: The Journal of biological chemistry

Article Title: Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

doi: 10.1074/jbc.272.16.10882

Figure Lengend Snippet: FIG. 8. Activation of Cdk4 and Cdk2 following estrogen treatment. MCF-7 cells were pretreated with 10 nM ICI 182780 for 48 h and then treated with 100 nM E2 or vehicle (control) at time 0. At intervals thereafter, whole cell lysates were prepared and immunoprecipitated with antibodies to either Cdk4, cyclin E, or Cdk2, and then the kinase activity of the immunoprecipitates was determined by phosphorylation of GST-pRB773–923

Article Snippet: Antibodies used were rabbit polyclonal antisera to human cyclin D1 (29), human cyclin E (C-19; Santa Cruz Biotechnology), and human Cdk2 (M2; Santa Cruz Biotechnology).

Techniques: Activation Assay, Control, Immunoprecipitation, Activity Assay, Phospho-proteomics

Journal: The Journal of biological chemistry

Article Title: Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

doi: 10.1074/jbc.272.16.10882

Figure Lengend Snippet: FIG. 9. Composition of cyclin D1-as- sociated and cyclin E-associated complexes. MCF-7 cells were pretreated with 10 nM ICI 182780 for 48 h and then treated with 100 nM E2 or vehicle (control) at time 0. At intervals thereafter, whole cell lysates were prepared and immuno- precipitated with anti-cyclin D1 anti- serum or anti-cyclin E antibodies, and then these immunoprecipitates were sep- arated by SDS-PAGE and transferred to nitrocellulose membranes. A, cyclin D1 antiserum immunoprecipitates. The same filter was sequentially Western blotted for cyclin D1, Cdk4, p21, and p27. A rep- resentative blot is shown for each. B, rel- ative levels of cyclin D1 (E), Cdk4 (G), p21 (M), and p27 (f) were determined by den- sitometry and are expressed relative to the vehicle treated controls. Points repre- sent the mean of two separate experi- ments. C, cyclin E immunoprecipitates. The same filter was sequentially Western blotted for cyclin E, Cdk2, p21, and p27. A representative blot is shown for each. The asterisk marks the more mobile form of Cdk2 that is phosphorylated on Thr-160.

Article Snippet: Antibodies used were rabbit polyclonal antisera to human cyclin D1 (29), human cyclin E (C-19; Santa Cruz Biotechnology), and human Cdk2 (M2; Santa Cruz Biotechnology).

Techniques: Control, SDS Page, Western Blot

Journal: The Journal of biological chemistry

Article Title: Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

doi: 10.1074/jbc.272.16.10882

Figure Lengend Snippet: FIG. 10. Estrogen decreases inhibi- tory activity toward cyclin E-Cdk2. A, lysates were prepared from cells that were pretreated with antiestrogen and then treated with E2 (1) or vehicle (2). Active cyclin E-Cdk2 complexes that had been prepared from baculovirus-infected Sf9 cells were incubated with either lysis buffer only (labeled input) or with cell lysates. Lysates were also immunode- pleted with either anti-p27 antibodies, anti-p21 antibodies, or both and then in- cubated with recombinant cyclin E-Cdk2 complexes. Recombinant cyclin E-Cdk2 complexes were then recovered and as- sayed for histone (H1) kinase activity. The percentage of the input activity, de- fined as 100%, is also shown numerically below the autoradiograph. The same sam- ples were electrophoresed on a duplicate SDS-PAGE gel and then Western blotted for p21 and p27 to assess the binding of these proteins to recombinant cyclin E- Cdk2. B, the experiment described for panel A was repeated using either boiled lysis buffer (labeled input) or boiled ly- sates from cells treated with estradiol (1) or vehicle (2). C, MCF-7 cells were pre- treated with 10 nM ICI 182780 for 48 h and then treated with 100 nM estradiol or vehicle (control) at time 0. At intervals thereafter, whole cell lysates were pre- pared and assayed for cyclin E-Cdk2 in- hibitory activity as described for panel A.

Article Snippet: Antibodies used were rabbit polyclonal antisera to human cyclin D1 (29), human cyclin E (C-19; Santa Cruz Biotechnology), and human Cdk2 (M2; Santa Cruz Biotechnology).

Techniques: Activity Assay, Infection, Incubation, Lysis, Labeling, Recombinant, Autoradiography, SDS Page, Western Blot, Binding Assay, Control

Journal: The Journal of biological chemistry

Article Title: Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

doi: 10.1074/jbc.272.16.10882

Figure Lengend Snippet: FIG. 11. Cyclin E-Cdk2 activation is accompanied by loss of CDK inhibitor association and Cdk2 Thr-160 phosphorylation. MCF-7 cells were pretreated with 10 nM ICI 182780 for 48 h and then treated with 100 nM E2 or vehicle (control) at time 0. Whole cell lysates were prepared either 8 h after estrogen (8 h E2) or from control cells (ICI 182780). Lysates were then fractionated on a Superose 12 gel filtration column. A, fractions were precipitated with acetone and Western blot- ted for cyclin E (top panels) or assayed for cyclin E-Cdk2 histone (H1) kinase activity (bottom panel). The relative levels of cyclin E protein (E, G) and cyclin E-Cdk2 activity (M, f) in lysates from antiestrogen- pretreated cells and cells treated with estradiol for 8 h were determined by densitometry and are represented graphically. The elution of mark- ers of known molecular weight (ferritin, 440 kDa; catalase, 232 kDa; aldolase, 158 kDa) are indicated at the top of the graph. B, fractions 19 and 24 from the 8 h E2 lysate were immunoprecipitated with an anti- cyclin E antibody, and the immunoprecipitates were electrophoresed on a SDS-PAGE gel and transferred to a nitrocellulose filter. The same filter was then sequentially Western blotted for cyclin E, Cdk2, p21, and p27. A representative blot is shown for each. The asterisk marks the more mobile form of Cdk2 that is phosphorylated on Thr-160.

Article Snippet: Antibodies used were rabbit polyclonal antisera to human cyclin D1 (29), human cyclin E (C-19; Santa Cruz Biotechnology), and human Cdk2 (M2; Santa Cruz Biotechnology).

Techniques: Activation Assay, Phospho-proteomics, Control, Filtration, Western Blot, Activity Assay, Molecular Weight, Immunoprecipitation, SDS Page