Biology subjects

Stippec, S.

Publications and source records attributed to Stippec, S..

3 recordsLinked to original sources

bioRxiv2024

Predictive and Experimental Motif Interaction Analysis Identifies Functions of the WNK-OSR1/SPAK Pathway

The WNK-OSR1/SPAK protein kinase signaling pathway regulates ion homeostasis and cell volume, but its other functions are poorly understood. To uncover undefined signaling functions of the pathway we analyzed the binding specificity of the conserved C-terminal (CCT) domains of OSR1 and SPAK to find all possible interaction motifs in human proteins. These kinases bind the core consensus sequences R-F-x-V/I and R-x-F-x-V/I. Motifs were ranked based on sequence, conservation, cellular localization, and solvent accessibility. Out of nearly 3,700 motifs identified, 90% of previously published motifs were within the top 2% of those predicted. Selected candidates (TSC22D1, CAVIN1, ATG9A, NOS3, ARHGEF5) were tested. Upstream kinases WNKs 1-4 and their close relatives, the pseudokinases NRBP1/2, contain CCT-like domains as well. We identified additional distinct motif variants lacking the conserved arginine previously thought to be required, and found that the NRBP1 CCT-like domain binds TSC22D1 via the same motif as OSR1 and SPAK. Our results further highlight the rich and diverse functionality of CCT and CCT-like domains in connecting WNK signaling to cellular processes.

biochemistry↗

bioRxiv2024

The Cancer Testis Antigen Testis Specific Serine Kinase 6 (TSSK6) is abnormally expressed in colorectal cancer and is essential for oncogenic behaviors

Cancer testis antigens (CTAs) are a collection of proteins whose expression is normally restricted to the gamete, but abnormally activated in a wide variety of tumors. The CTA, Testis specific serine kinase 6 (TSSK6), is essential for male fertility in mice. Functional relevance of TSSK6 to cancer, if any, has not previously been investigated. Here we find that TSSK6 is frequently anomalously expressed in colorectal cancer and patients with elevated TSSK6 expression have reduced relapse free survival. Depletion of TSSK6 from colorectal cancer cells attenuates anchorage independent growth, invasion and growth in vivo. Conversely, overexpression of TSSK6 enhances anchorage independence and invasion in vitro as well as in vivo tumor growth. Notably, ectopic expression of TSSK6 in semi-transformed human colonic epithelial cells is sufficient to confer anchorage independence and enhance invasion. In somatic cells, TSSK6 co-localizes with and enhances the formation of paxillin and tensin positive foci at the cell periphery, suggesting a function in focal adhesion formation. Importantly, TSSK6 kinase activity is essential to induce these tumorigenic behaviors. Our findings establish that TSSK6 exhibits oncogenic activity when abnormally expressed in colorectal cancer cells. Thus, TSSK6 is a previously unrecognized intervention target for therapy, which could exhibit an exceptionally broad therapeutic window.

cancer biology↗

bioRxiv2019

ERK2 phosphorylates the epigenetic regulator CXXC-finger protein 1 (Cfp1)

BackgroundThe Ras-Raf-MEK-ERK signaling pathway is essential for proper development and homeostatic regulation in eukaryotic cells and underlies progression of several types of cancer. Many pathway functions are performed by extracellular signal-regulated kinase (ERK)1 and 2 (ERK1/2), serine/threonine protein kinases of the mitogen-activated protein kinase (MAPK) family that interact with a large number of substrates and are highly active in the nucleus.\n\nResultsWe identified the epigenetic regulator CXXC-finger protein 1 (CFP1) as a protein that interacts with ERK2 on chromatin. CFP1 is involved in multiple aspects of chromatin regulation, including histone methylation and DNA methylation. Here, we demonstrate the overlapping roles for ERK1/2 and CFP1 in regulation of immediate early gene (IEG) induction. Our work suggests multiple modes of co-regulation and demonstrates that CFP1 is required for an optimal signal-dependent response. We also show that CFP1 is an ERK2 substrate in vitro and identify several phosphorylation sites. Furthermore, we provide evidence that Su(var)3-9, Enhancer-of-zeste and Trithorax (Set)1b, a CFP1-interacting histone methylase, is phosphorylated by ERK2 and is regulated by CFP1.\n\nConclusionOur work highlights ERK1/2 interactions with chromatin regulators that contribute to MAPK signaling diversity in the nucleus.

cell biology↗