Cell-Intrinsic Adaptation Arising from Chronic Ablation of a Key Rho GTPase Regulator.
Genome-editing technologies allow systematic inactivation of human genes. Whether knockout phenotypes always reflect gene functions as determined by acute RNAi is an important question. Here we show how the acute knockdown of the Adams-Oliver syndrome (AOS) gene DOCK6, coding for a RAC1/CDC42 guanine nucleotide exchange factor, results in strikingly different phenotypes to those generated by genomic DOCK6 disruption. Cell-intrinsic adaptation compensates for loss of DOCK6 function. Prolonged DOCK6 loss impacts upon the MRTF-A/SRF transcription factor, reducing levels of the ubiquitin-like modifier ISG15. Reduced ISGylation of the IQGAP1 protein increases levels of active CDC42 and RAC1 to compensate for DOCK6 disruption. Similar downregulation of ISG15 in cells from DOCK6 AOS patients indicates that such adaptation can compensate for genetic defects during development. Thus, phenotypes of gene inactivation are critically dependent on the timescale, as acute knockdown reflects a transient state of adjustment to a new equilibrium that is attained following compensation.
Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69117 Heidelberg, Germany; The Hartmut Hoffmann-Berling International Graduate School of Molecular and Cellular Biology (HBIGS), University of Heidelberg, 69120 Heidelberg, Germany.
Berati
B
Cerikan
Department of Genetics, King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia.
Ranad
R
Shaheen
Department of Molecular Medicine, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
Georgina P
GP
Colo
Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69117 Heidelberg, Germany.
Christine
C
Gläßer
Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69117 Heidelberg, Germany.
Shoji
S
Hata
Institute of Neuropathology, Faculty of Medicine, University of Freiburg, Breisacher Straße 64, 79106 Freiburg, Germany.
Klaus-Peter
KP
Knobeloch
Department of Genetics, King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia.
Fowzan S
FS
Alkuraya
Department of Molecular Medicine, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
Reinhard
R
Fässler
Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69117 Heidelberg, Germany. Electronic address: e.schiebel@zmbh.uni-heidelberg.de.
Elmar
E
Schiebel
D008841:Actin Cytoskeleton / Q000378:metabolism; D000222:Adaptation, Physiological; D002465:Cell Movement; D016207:Cytokines / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D004476:Ectodermal Dysplasia / Q000235:genetics / Q000473:pathology; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D055786:Gene Knockout Techniques; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D017880:Limb Deformities, Congenital / Q000235:genetics / Q000473:pathology; D008938:Mitosis; D010641:Phenotype; D012536:Scalp Dermatoses / Q000151:congenital / Q000235:genetics / Q000473:pathology; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020703:ras GTPase-Activating Proteins / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D016207:Cytokines; C000607938:DOCK6 protein, human; D020662:Guanine Nucleotide Exchange Factors; C101203:IQ motif containing GTPase activating protein 1; D014157:Transcription Factors; D025801:Ubiquitin; D014452:Ubiquitins; D020703:ras GTPase-Activating Proteins; C074034:ISG15 protein, human; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D018631:ras Proteins; D020741:rho GTP-Binding Proteins