Biology subjects

Adams, M. K.

Publications and source records attributed to Adams, M. K..

4 recordsLinked to original sources

bioRxiv2021

Perturbation of BRMS1 interactome reveals pathways that impact cell migration

Breast Cancer Metastasis Suppressor 1 (BRMS1) expression is associated with longer patient survival in multiple cancer types. Understanding BRMS1 functionality will provide insights into both mechanism of action and will enhance potential therapeutic development. In this study, we confirmed that the C-terminus of BRMS1 is critical for metastasis suppression and hypothesized that critical protein interactions in this region would explain its function. Phosphorylation status at S237 regulates BRMS1 protein interactions related to a variety of biological processes, phenotypes [cell cycle (e.g., CDKN2A), DNA repair (e.g., BRCA1)], and metastasis [(e.g., TCF2 and POLE2)]. Presence of S237 also directly decreased MDA-MB-231 breast carcinoma migration in vitro and metastases in vivo. The results add significantly to our understanding of how BRMS1 interactions with Sin3/HDAC complexes regulate metastasis and expand insights into BRMS1s molecular role, as they demonstrate that BRMS1 C-terminus involvement in distinct direct protein-protein interactions.

cancer biology↗

bioRxiv2020

Orai1- and Orai2-, but not Orai3-mediated ICRAC is regulated by intracellular pH

Three Orai (Orai1, Orai2 and Orai3) and two STIM (STIM1 and STIM2; stromal interaction molecule) mammalian protein homologues constitute major components of the store-operated Ca2+ entry mechanism. When co-expressed with STIM1, Orai1, Orai2 and Orai3 form highly selective Ca2+ channels with properties of Ca2+ release activated Ca2+ (CRAC) channels. Despite the high level of homology between Orai proteins, CRAC channels formed by different Orai isoforms have distinctive properties, particularly with regards to Ca2+ dependent inactivation, inhibition/potentiation by 2-APB and sensitivity to reactive oxygen species. This study characterises and compares the regulation of Orai1, Orai2- and Orai3-mediated CRAC current (ICRAC) by intracellular pH. Using whole-cell patch clamping of HEK293T cells heterologously expressing Orai and STIM1 we show that ICRAC formed by each Orai homologue has a unique sensitivity to changes in intracellular pH (pHi). Orai1-mediated ICRAC exhibits a strong dependence on pHi of both current amplitude and the kinetics of Ca2+ dependent inactivation. In contrast, Orai2 amplitude, but not kinetics, depends on pHi, whereas Orai3 shows no dependence on pHi at all. Investigation of different Orai1-Orai3 chimeras suggests that pHi dependence of Orai1 resides in both, the N-terminus and intracellular loop 2, and may also involve pH-dependent interactions with STIM1.

physiology↗

bioRxiv2019

Differential complex formation via paralogs in the human Sin3 protein interaction network.

Despite the continued analysis of HDAC inhibitor efficacy in clinical trials, the heterogeneous nature of the protein complexes they target limits our understanding of the beneficial and off-target effects associated with their application. Among the many HDAC protein complexes found within the cell, Sin3 complexes are conserved from yeast to humans and likely play important roles as regulators of transcriptional activity. The functional attributes of these protein complexes remain poorly characterized in humans. Contributing to the poor definition of Sin3 complex attributes in higher eukaryotes is the presence of two Sin3 scaffolding proteins, SIN3A and SIN3B. Here we show that paralog switching influences the interaction networks of the Sin3 complexes. While SIN3A and SIN3B do have unique interaction network components, we find that SIN3A and SIN3B interact with a common set of proteins. Additionally, our results suggest that SIN3A and SIN3B may possess the capacity to form hetero-oligomeric complexes. While one principal form of SIN3B exists in humans, the analysis of rare SIN3B proteoforms provides insight into the domain organization of SIN3B. Together, these findings shed light on the shared and divergent properties of human Sin3 proteins and highlight the heterogeneous nature of the complexes they organize.

systems biology↗

bioRxiv2019

Integrative Modeling of a Sin3/HDAC Complex Sub-structure

Sin3/HDAC complexes function by deacetylating histones, which makes chromatin more compact and modulates gene expression. Although components used to build these complexes have been well defined, we still have only a limited understanding of the structure of the Sin3/HDAC subunits as they are assembled around the scaffolding protein SIN3A. To characterize the spatial arrangement of Sin3 subunits, we combined Halo affinity capture, chemical cross-linking and high-resolution mass spectrometry (XL-MS) to determine intersubunit distance constraints, identifying 66 high-confidence interprotein and 63 high-confidence self cross-links for 13 Sin3 subunits. To validate our XL-MS data, we first mapped self cross-links onto existing structures to verify that cross-link distances were consistent with cross-linker length and subsequently deleted crosslink hotspot regions within the SIN3A scaffolding protein which then failed to capture crosslinked partners. Having assessed cross-link authenticity, we next used distance restraints from interprotein cross-links to guide assembly of a Sin3 complex substructure. We identified the relative positions of subunits SAP30L, HDAC1, SUDS3, HDAC2, and ING1 around the SIN3A scaffold. The architecture of this subassembly suggests that multiple factors have space to assemble to collectively influence the behavior of the catalytic subunit HDAC1.

biochemistry↗