Generation of conditional knockout alleles for PRL-3

The PACT Network: PRL, ARL, CNNM, and TRPM Proteins in Magnesium Transport and Disease

Magnesium, the most abundant divalent metal within the cell, is essential for physiological function and critical in cellular signaling. To maintain cellular homeostasis, intracellular magnesium levels are tightly regulated, as dysregulation is linked to numerous diseases, including cancer, diabetes, cardiovascular disorders, and neurological conditions. Over the past two decades, extensive research on magnesium-regulating proteins has provided valuable insight into their pathogenic and therapeutic potential. This review explores an emerging mechanism of magnesium homeostasis involving proteins in the PRL (phosphatase of regenerating liver), ARL (ADP ribosylation factor-like GTPase family), CNNM (cyclin and cystathionine β-synthase domain magnesium transport mediator), and TRPM (transient receptor potential melastatin) families, collectively termed herein as the PACT network. While each PACT protein has been studied within its individual signaling and disease contexts, their interactions suggest a broader regulatory network with therapeutic potential. This review consolidates the current knowledge on the PACT proteins' structure, function, and interactions and identifies research gaps to encourage future investigation. As the field of magnesium homeostasis continues to advance, understanding PACT protein interactions offers new opportunities for basic research and therapeutic development targeting magnesium-related disorders.

Drosophila Phosphatase of Regenerating Liver Is Critical for Photoreceptor Cell Polarity and Survival during Retinal Development

Establishing apicobasal polarity, involving intricate interactions among polarity regulators, is key for epithelial cell function. Though phosphatase of regenerating liver (PRL) proteins are implicated in diverse biological processes, including cancer, their developmental role remains unclear. In this study, we explore the role of Drosophila PRL (dPRL) in photoreceptor cell development. We reveal that dPRL, requiring a C-terminal prenylation motif, is highly enriched in the apical membrane of developing photoreceptor cells. Moreover, dPRL knockdown during retinal development results in adult Drosophila retinal degeneration, caused by hid-induced apoptosis. dPRL depletion also mislocalizes cell adhesion and polarity proteins like Armadillo, Crumbs, and DaPKC and relocates the basolateral protein, alpha subunit of Na⁺/K⁺-ATPase, to the presumed apical membrane. Importantly, this polarity disruption is not secondary to apoptosis, as suppressing hid expression does not rescue the polarity defect in dPRL-depleted photoreceptor cells. These findings underscore dPRL's crucial role in photoreceptor cell polarity and emphasize PRL's importance in establishing epithelial polarity and maintaining cell survival during retinal development, offering new insights into PRL's role in normal epithelium.

The role of protein tyrosine phosphatases in colorectal cancer

Colorectal cancer is one of the most common oncogenic diseases in the Western world. Several cancer associated cellular pathways have been identified, in which protein phosphorylation and dephosphorylation, especially on tyrosine residues, are one of most abundant regulatory mechanisms. The balance between these processes is under tight control by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Aberrant activity of oncogenic PTKs is present in a large portion of human cancers. Because of the counteracting role of PTPs on phosphorylation-based activation of signal pathways, it has long been thought that PTPs must act as tumor suppressors. This dogma is now being challenged, with recent evidence showing that dephosphorylation events induced by some PTPs may actually stimulate tumor formation. As such, PTPs might form a novel attractive target for anticancer therapy. In this review, we summarize the action of different PTPs, the consequences of their altered expression in colorectal cancer, and their potential as target for the treatment of this deadly disease.