TSC22D, WNK and NRBP gene families exhibit functional buffering and evolved with Metazoa for cell volume regulation
Ontology highlight
ABSTRACT: The ability to sense and respond to osmotic fluctuations is critical for the maintenance of cellular integrity. We used gene co-essentiality analysis to identify an unappreciated relationship between TSC22D2, WNK1 and NRBP1 in regulating cell volume homeostasis. Each of these genes have paralogs and are functionally buffered for osmo-sensing and cell volume control. Within seconds of hyperosmotic stress, TSC22D, WNK and NRBP family members physically associate into biomolecular condensates, a process that is dependent on intrinsically disordered regions (IDRs). A close examination of these protein families across metazoans revealed that TSC22D genes evolved alongside a domain in NRBPs that specifically binds to TSC22D proteins, which we have termed NbrT (NRBP binding region with TSC22D), and this co-evolution is accompanied by rapid IDR length expansion in WNK family kinases. Our study reveals that TSC22D, WNK and NRBP genes evolved in metazoans to co-regulate rapid cell volume changes in response to osmolarity.
Project description:The BTB-Kelch protein KLHL3 is a Cullin3-dependent E3 ligase that mediates the ubiquitin-dependent degradation of kinases WNK1-4 to control blood pressure and cell volume. A crystal structure of KLHL3 has defined its binding to an acidic degron motif containing a PXXP sequence that is strictly conserved in WNK1, WNK2 and WNK4. Mutations in the second proline abrograte the interaction causing the hypertension syndrome pseudohypoaldosteronism type II. WNK3 shows a diverged degron motif containing 4 amino acid substitutions that remove the PXXP motif raising questions as to the mechanism of its binding. To understand this atypical interaction, we determined the crystal structure of the KLHL3 Kelch domain in complex with a WNK3 peptide. The electron density enabled the complete 11-mer WNK-family degron motif to be traced for the first time revealing several conserved features not captured in previous work, including additional salt bridge and hydrogen bond interactions. Overall, the WNK3 peptide adopted a conserved binding pose except for a subtle shift to accommodate bulkier amino acid substitutions at the binding interface. At the centre, the second proline was substituted by WNK3 Thr541, providing a unique phosphorylatable residue among the WNK-family degrons. Fluorescence polarisation and structural modelling experiments revealed that its phosphorylation would abrogate the KLHL3 interaction similarly to hypertension-causing mutations. Together, these data reveal how the KLHL3 Kelch domain can accommodate the binding of multiple WNK isoforms and highlight a potential regulatory mechanism for the recruitment of WNK3.
Project description:Multiple myeloma (MM) remains a challenging hematological malignancy demanding innovative therapeutic strategies. Targeting MYC, the notorious yet traditionally undruggable oncogene, presents an appealing avenue. Here, using a genome-scale CRISPR/Cas9 screen, we identify the WNK lysine deficient protein kinase 1 (WNK1) as a regulator of MYC expression in MM cells. Genetic and pharmacological inhibition of WNK1 reduces MYC expression, and further, disrupts the MYC-dependent transcriptional program. Mechanistically, WNK1 inhibition attenuates the activity of the immunoglobulin heavy chain (IgH) enhancer, thus reducing MYC transcription when this locus is translocated near the MYC locus. WNK1 inhibition profoundly impacts MM cell behaviors, leading to growth inhibition, cell cycle arrest, senescence, and apoptosis. Importantly, the WNK inhibitor WNK463 synergizes with various anti-MM compounds, and inhibits MM growth in primary patient samples as well as xenograft mouse models. Collectively, our study uncovers WNK1 as a potential therapeutic target in MM.
Project description:The protrotophic laboratory strain CEN.PK113-7D (MAT a) was grown in laboratory fermentors with a working volume of 1 litre at dilution rate (D) of 0.20 per hour (in duplicate for each nitrogen (glutamine and ammonium) limited condition). After cultivation for few hundred generations in ammonium, samples from 2 continuous cultures were taken for array analysis. After cultivation for few hundred generations in glutamine, one evolved strain was picked and cultivated in 2 biological replicate chemostats until steady state was reached, and samples for array analysis were collected. All collected cell samples were cooled below 2 degree C within ten seconds by mixing 40% sample and 60% crushed ice.
Project description:Regulation of cell volume is essential for tissue homeostasis and cell viability. In response to hypertonic stress, cells need rapid electrolyte influx to compensate water loss and to prevent cell death in a process known as regulatory volume increase (RVI). However, the molecular component able to trigger such process was unknown to date. Using a genome wide CRISPR/Cas9 screen, we identified LRRC8A, which encodes a chloride channel subunit, as the gene most associated with cell survival under hypertonic conditions. Hypertonicity activates the p38 stress-activated protein kinase pathway and its downstream MSK1 kinase, which phosphorylates and activates LRRC8A. LRRC8A-mediated Cl efflux facilitates activation of the with-no-lysine (WNK) kinase pathway, which in turn, promotes electrolyte influx via Na+ /K+ /2Cl cotransporter (NKCC) and RVI under hypertonic stress. LRRC8A-S217A mutation impairs channel activation by MSK1, resulting in reduced RVI and cell survival. In summary, LRRC8A is key to bidirectional osmotic stress responses and cell survival under hypertonic conditions.
Project description:In the present study, we investigated the molecular mechanisms by which Wnk contributes to human corneal epithelial wound healing. To better understand the process, we cultivated human corneal epithelial cells without or with Wnk inhibitor. Using gene profiling, we compared the mRNA profiles of passage 3 human corneal epithelial cells cultivated without Wnk inhibitor with passage 3 human corneal epithelial cells cultivated with Wnk inhibitor. Human corneal epithelial cells are isolated from eye bank donor corneas.
Project description:RNAseq was used to analyse transcriptional changes occuring in WNK1-expressing or WNK1-deficient DN3 thymocytes following injection of anti-CD3e
Project description:The kinase protein WNK1 is highly expressed and phosphorylated in the testis, suggesting possible functions in regulating male fertility. Indeed, conditional pachytene-spermatocyte Wnk1 knock-out mice generated using the novel Wnt7a-Cre failed to produce functional sperm which resulted from the primary spermatogenic arrest during mid-pachynema. Global transcriptomic approaches identified ‘translation’ as one of the impacted events in Wnk1-depleted spermatocytes.
Project description:The plant signaling molecule auxin controls growth and development through a simple nuclear pathway that regulates the expression of numerous genes. There are however several cellular and physiological responses to auxin that occur within seconds, far too rapid to be mediated by gene expression changes, for which no molecular mechanism has yet been identified. Using a phosphoproteomic strategy in Arabidopsis thaliana roots, an ultra-rapid auxin response system that targets >2000 proteins of which many within 30 seconds was identified.