Loss of Prkar1a leads to Bcl-2 family protein induction and cachexia in mice

Abstract

Loss of function mutations in the Prkar1a gene are the cause of most cases of Carney complex disorder. Defects in Prkar1a are thought to cause hyper-activation of PKA signalling, which drives neoplastic transformation, and Prkar1a is therefore considered to be a tumour suppressor. Here we show that loss of Prkar1a in genetically modified mice caused transcriptional activation of several proapoptotic Bcl-2 family members and thereby caused cell death. Interestingly, combined loss of Bim and Prkar1a increased colony formation of fibroblasts in culture and promoted their growth as tumours in immune-deficient mice. Apart from inducing apoptosis, systemic deletion of Prkar1a caused cachexia with muscle loss, macrophage activation and increased lipolysis as well as serum triglyceride levels. Loss of single allele of Prkar1a did not enhance tumour development in a skin cancer model, but surprisingly, when combined with the loss of Bim, caused a significant delay in tumorigenesis and this was associated with upregulation of other BH3-only proteins, PUMA and NOXA. These results show that loss of Prkar1a can only promote tumorigenesis when Prkar1a-mediated apoptosis is somehow countered.

Chemical chaperone TUDCA prevents apoptosis and improves survival during polymicrobial sepsis in mice

“…For cell death assay, cells were stained with annexin V-FITC or annexin V-AF688 (in house reagents) at the indicated time points at appropriate dilutions followed by PI staining (1 μg/ml, final concentration). For measuring apoptosis in tissue sections at the indicated time points, TUNEL staining was carried out as described previously 33 .…”

“…Protein analysis was carried out by Western blot analysis as described before. 9 RNA analysis was carried out by digital PCR as described before 33 . The oligos used for digital PCR were XBP1-S (F): 5′-AAGAACACGCTTGGGAATGG-3′, XBP1-S (R): 5′-CTGCACCTGCTGCGGAC-3′; BIM (F): 5′-CGACAGTCTCAGGAGGAACC-3′, BIM (R): 5′-CCTTCTCCATACCAGACGGA-3′; PUMA (F): 5′-GCTGAAGGACTCATGGTGAC-3′ and PUMA (R): 5′-CAAAGTGAAGGCGCACTG-3′.…”

A siRNA screen reveals the prosurvival effect of protein kinase A activation in conditions of unresolved endoplasmic reticulum stress

“…25,26 In addition, PKA activation has been reported to not only prevent but also promote apoptosis, and the molecular explanation for this paradox has not been solved yet. 15,[27][28][29] Because the UPR has a dual role in the response to ER stress, we decided to first analyze whether PKA activation had any impact on the initiation and/or intensity of the UPR. Using conditions of transient PKA activation (siRNA-mediated repression of Prkar1a) or sustained PKA activation (genetic deletion of Prkar1a), we followed induction of various classical UPR markers over a period of 20 h of Tu stimulation.…”

“…29,34 In line with this, genetic deletion of Prkar1a leads to early embryonic lethality in mice, 35,36 and its inducible loss in diverse adult tissues is reported to trigger PKA activation and apoptosis because of the upregulation of proapoptotic BCL-2 family members. 15 Paradoxically, PKA is also reported to promote cell survival and its hyperactivation causes hereditary endocrine neoplasias. Indeed, heterogenic mutations in the human PRKAR1A gene, which leads to overactivation of the PKA signaling pathway, are strongly associated with a disorder called Carney complex, a rare autosomal dominant disorder characterized by hyperpigmentation of the skin, cardiac and other myxomas, endocrine tumors and schwannomas.…”

Sporadic Carney Complex without PRKAR1A Mutation in a Young Patient with Ischemic Stroke

“…1 In two thirds of the patients, it is caused by inactivating mutations of the protein kinase A regulatory subunit-1-alpha gene (PRKAR1A), 2 which encodes a regulatory subunit of cAMP-dependent protein kinase A, being considered a tumor suppressor. 1,3 However, there are no significant differences observed between patients with clinical features of CNC who carry a PRKAR1A mutation and those who do not. 4 CNC features cardiac, endocrine, cutaneous, and neural tumors, as well as a variety of pigmented lesions of the skin and mucosae (OMIM 160980).…”