Chronic angiotensin-converting enzyme inhibition up-regulates mouse kidney growth arrest specific-6 protein and the AXL subfamily of receptor tyrosine kinases

Vitamin K Dependent Proteins in Kidney Disease

Patients with chronic kidney disease (CKD) have an increased risk of developing vascular calcifications, as well as bone dynamics impairment, leading to a poor quality of life and increased mortality. Certain vitamin K dependent proteins (VKDPs) act mainly as calcification inhibitors, but their involvement in the onset and progression of CKD are not completely elucidated. This review is an update of the current state of knowledge about the relationship between CKD and four extrahepatic VKDPs: matrix Gla protein, osteocalcin, growth-arrest specific protein 6 and Gla-rich protein. Based on published literature in the last ten years, the purpose of this review is to address fundamental aspects about the link between CKD and circulating VKDPs levels as well as to raise new topics about how the interplay between molecular weight and charge could influence the modifications of circulating VKDPs at the glomerular level, or whether distinct renal etiologies have effect on VKDPs. This review is the output of a systematic literature search and may open future research avenues in this niche domain.

Axl as a mediator of cellular growth and survival

The control of cellular growth and proliferation is key to the maintenance of homeostasis. Survival, proliferation, and arrest are regulated, in part, by Growth Arrest Specific 6 (Gas6) through binding to members of the TAM receptor tyrosine kinase family. Activation of the TAM receptors leads to downstream signaling through common kinases, but the exact mechanism within each cellular context varies and remains to be completely elucidated. Deregulation of the TAM family, due to its central role in mediating cellular proliferation, has been implicated in multiple diseases. Axl was cloned as the first TAM receptor in a search for genes involved in the progression of chronic to acute-phase leukemia, and has since been established as playing a critical role in the progression of cancer. The oncogenic nature of Axl is demonstrated through its activation of signaling pathways involved in proliferation, migration, inhibition of apoptosis, and therapeutic resistance. Despite its recent discovery, significant progress has been made in the development of effective clinical therapeutics targeting Axl. In order to accurately define the role of Axl in normal and diseased processes, it must be analyzed in a cell type-specific context.