Drosophila Morgana is an Hsp90-interacting protein with a direct role in microtubule polymerisation

The evolution and diversification of the Hsp90 co-chaperone system

The molecular chaperone Hsp90 is the central element of a chaperone machinery in the cytosol of eukaryotic cells that is characterized by a large number of structurally and functionally different co-chaperones that influence the core chaperone component in different ways and increase its influence on the proteome. From yeast to humans, the number of Hsp90 co-chaperones has increased from 14 to over 40, and new co-chaperones are still being discovered. While Hsp90 itself has only undergone limited changes in structure and mechanism from yeast to humans, its increased importance and contribution to different processes in humans is based on the evolution and expansion of the cohort of co-chaperones. In this review, we provide an overview of Hsp90 co-chaperones, focusing on their roles in regulating Hsp90 function and their evolution from yeast to humans.

miR-15a targets the HSP90 co-chaperone Morgana in chronic myeloid leukemia

Morgana is a ubiquitous HSP90 co-chaperone protein coded by the CHORDC1 gene. Morgana heterozygous mice develop with age a myeloid malignancy resembling human atypical myeloid leukemia (aCML), now renamed MDS/MPN with neutrophilia. Patients affected by this pathology exhibit low Morgana levels in the bone marrow (BM), suggesting that Morgana downregulation plays a causative role in the human malignancy. A decrease in Morgana expression levels is also evident in the BM of a subgroup of Philadelphia-positive (Ph+) chronic myeloid leukemia (CML) patients showing resistance or an incomplete response to imatinib. Despite the relevance of these data, the mechanism through which Morgana expression is downregulated in patients' bone marrow remains unclear. In this study, we investigated the possibility that Morgana expression is regulated by miRNAs and we demonstrated that Morgana is under the control of four miRNAs (miR-15a/b and miR-26a/b) and that miR-15a may account for Morgana downregulation in CML patients.

Extracellular HSP90 Machineries Build Tumor Microenvironment and Boost Cancer Progression

HSP90 is released by cancer cells in the tumor microenvironment where it associates with different co-chaperones generating complexes with specific functions, ranging from folding and activation of extracellular clients to the stimulation of cell surface receptors. Emerging data indicate that these functions are essential for tumor growth and progression. The understanding of the exact composition of extracellular HSP90 complexes and the molecular mechanisms at the basis of their functions in the tumor microenvironment may represent the first step to design innovative diagnostic tools and new effective therapies. Here we review the impact of extracellular HSP90 complexes on cancer cell signaling and behavior.

Oncolytic Virus Affects the RAS Pathway in Cancer: RNA Sequence Analysis

BACKGROUND

Approximately 45% of individuals diagnosed with Colorectal Cancer (CRC) also possess KRAS mutations. One developing therapeutic method for this disease is reovirus treatment. It is theorized that reovirus treatment on patients with KRAS mutated CRC cells would be successful due to the virus' innate oncolytic properties [1]. Reovirus, a stable form of nonenveloped double-stranded RNA, causes minor infections in humans under normal circumstances. However, when the virus encounters KRAS mutated cells, it has the potential to lyse them [2]. While this method of treatment to CRC has shown signs of success, we are still some ways from universal administration of reovirus as a treatment. This review seeks to utilize various studies, as well as our original research data, to investigate reovirus as an efficient method of treatment, with a focus on select growth, apoptotic and RAS-related genes, and their effectiveness of mitigating KRAS mutated CRC post reovirus treatment. Furthermore, the review highlights transcriptome analysis as an effective tool to examine these genes and their activity. It has been shown that reovirus treatment induces apoptosis and mitigates growth related gene activity.

CONCLUSIONS

This review confirms the novelty of our findings on the efficacy of reovirus in CRC treatment. The study that this review article discusses concluded that 10 apoptotic and lymphocyte-related genes were found to be upregulated and 6 angiogenesis and Ras-related genes were found to be downregulated post reovirus treatment. These findings enforce the notion that reovirus could be used as a novel treatment for KRAS mutated CRC.

The CHORD protein CHP-1 regulates EGF receptor trafficking and signaling in C. elegans and in human cells

The intracellular trafficking of growth factor receptors determines the activity of their downstream signaling pathways. Here, we show that the putative HSP-90 co-chaperone CHP-1 acts as a regulator of EGFR trafficking in C. elegans. Loss of chp-1 causes the retention of the EGFR in the ER and decreases MAPK signaling. CHP-1 is specifically required for EGFR trafficking, as the localization of other transmembrane receptors is unaltered in chp-1(lf) mutants, and the inhibition of hsp-90 or other co-chaperones does not affect EGFR localization. The role of the CHP-1 homolog CHORDC1 during EGFR trafficking is conserved in human cells. Analogous to C. elegans, the response of CHORDC1-deficient A431 cells to EGF stimulation is attenuated, the EGFR accumulates in the ER and ERK2 activity decreases. Although CHP-1 has been proposed to act as a co-chaperone for HSP90, our data indicate that CHP-1 plays an HSP90-independent function in controlling EGFR trafficking through the ER.