| Autor: |
Huang L; Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007.; BioSNTR, Brookings, SD 57007., Thiex NW; Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007.; BioSNTR, Brookings, SD 57007., Lou J; Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007., Ahmad G; Eppley Institute for Research in Cancer and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198., An W; Eppley Institute for Research in Cancer and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198., Low-Nam ST; Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007., Kerkvliet JG; Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007.; BioSNTR, Brookings, SD 57007., Band H; Eppley Institute for Research in Cancer and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198., Hoppe AD; Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007.; BioSNTR, Brookings, SD 57007. |
| Abstrakt: |
The ubiquitination of transmembrane receptors regulates endocytosis, intracellular traffic, and signal transduction. Bone marrow-derived macrophages from myeloid Cbl -/- and Cbl-b -/- double knockout (DKO) mice display sustained proliferation mirroring the myeloproliferative disease that these mice succumb to. Here, we found that the ubiquitin ligases Cbl and Cbl-b have overlapping functions for controlling the endocytosis and intracellular traffic of the CSF-1R. DKO macrophages displayed complete loss of ubiquitination of the CSF-1R whereas partial ubiquitination was observed for either single Cbl -/- or Cbl-b -/- macrophages. Unlike wild type, DKO macrophages were immortal and displayed slower CSF-1R internalization, elevated AKT signaling, and a failure to transport the CSF-1R into the lumen of nascent macropinosomes, leaving its cytoplasmic region available for signaling. CSF-1R degradation depended upon lysosomal vATPase activity in both WT and DKO macrophages, with this degradation confined to macropinosomes in WT but occurring in distributed/tubular lysosomes in DKO cells. RNA-sequencing comparison of Cbl -/- , Cbl-b -/- and DKO macrophages indicated that while the overall macrophage transcriptional program remained intact, DKO macrophages had alterations in gene expression associated with growth factor signaling, cell cycle, inflammation and senescence. Cbl-b -/- had minimal effect on the transcriptional program whereas Cbl -/- led to more alternations but only DKO macrophages demonstrated substantial changes in the transcriptome, suggesting overlapping but unique functions for the two Cbl-family members. Thus, Cbl/Cbl-b-mediated ubiquitination of CSF-1R regulates its endocytic fate, constrains inflammatory gene expression, and regulates signaling for macrophage proliferation. |
