Phenylbutyrate rescues the transport defect of the Sec61α mutations V67G and T185A for renin

Abstract

The human Sec61 complex is a widely distributed and abundant molecular machine. It resides in the membrane of the endoplasmic reticulum to channel two types of cargo: protein substrates and calcium ions. The SEC61A1 gene encodes for the pore-forming Sec61α subunit of the Sec61 complex. Despite their ubiquitous expression, the idiopathic SEC61A1 missense mutations p.V67G and p.T185A trigger a localized disease pattern diagnosed as autosomal dominant tubulointerstitial kidney disease (ADTKD–SEC61A1). Using cellular disease models for ADTKD–SEC61A1, we identified an impaired protein transport of the renal secretory protein renin and a reduced abundance of regulatory calcium transporters, including SERCA2. Treatment with the molecular chaperone phenylbutyrate reversed the defective protein transport of renin and the imbalanced calcium homeostasis. Signal peptide substitution experiments pointed at targeting sequences as the cause for the substrate-specific impairment of protein transport in the presence of the V67G or T185A mutations. Similarly, dominant mutations in the signal peptide of renin also cause ADTKD and point to impaired transport of this renal hormone as important pathogenic feature for ADTKD–SEC61A1 patients as well.

Signal Peptide Features Determining the Substrate Specificities of Targeting and Translocation Components in Human ER Protein Import

“…In our opinion, gating of the Sec61 channel can best be described in analogy to an enzyme-catalyzed reaction where the precursor polypeptides with their SPs are the catalysts and the channel is their substrate ( Figures 1D , 7 ) ( Haßdenteufel et al, 2018 ): Channel opening and closing represent two energetically un-favorable reversible reactions and the clients with or without support from auxiliary components or allosteric effectors (TRAP, Sec62/Sec63, see below) are the co-catalysts, which lower the activation energy for the required conformational transitions by binding to the Sec61 complex ( Lang et al, 2017 ; Lang et al, 2019 ). Interestingly, there are SP mutations of certain precursor polypeptides, such as preproinsulin, preprorenin, as well as SEC61A1 mutations that can cause the same hereditary diseases, such as Diabetes mellitus and ADTKD ( Lloyd et al, 2010 ; Guo et al, 2014 ; Bolar et al, 2016 ; Devuyst et al, 2019 ; Sicking et al, 2022 ). Again, this can best be described by an energy diagram for Sec61 channel gating ( Figure 7 ).…”

“…Furthermore, ERj1 was found to be subject to phosphorylation ( Götz et al, 2009 ) and TRAPα was found to be subject to phosphorylation as well as Ca 2+ -binding ( Wada et al, 1991 ) and, therefore, may reciprocally respond to the same cellular conditions as compared to Sec62/Sec63. We are convinced that the detected variations in SP and TMH characteristics are responsible for the known precursor specific defects in various human diseases, termed Sec61-channelopathies (reviewed by Haßdenteufel et al, 2014 ; Sicking et al, 2021a ), which include SEC61A1 -linked Common variable immunodeficiency ( Schubert et al, 2018 ), Neutropenia ( Van Nieuwenhove et al, 2020 ) and Tubulointerstitial kidney disease ( Bolar et al, 2016 ; Sicking et al, 2022 ), SEC61B - and SEC63 -linked Polycystic liver disease ( Fedeles et al, 2011 ; Lang et al, 2012 ; Besse et al, 2017 ), and SSR - as well as CAML -linked Congenital disorders of glycosylation ( Pfeffer et al, 2017 ; Nguyen et al, 2018 ; Wilson et al, 2022 ) ( Table 1 ).…”

“…the reverse reaction. The SEC61A1 mutations that can cause the same hereditary diseases, such as Diabetes mellitus and ADTKD (Lloyd et al, 2010;Guo et al, 2014;Bolar et al, 2016;Devuyst et al, 2019;Sicking et al, 2022). Again, this can best be described by an energy diagram for Sec61 channel gating (Figure 7).…”

Effect of CB2 Stimulation on Gene Expression in Pediatric B-Acute Lymphoblastic Leukemia: New Possible Targets

“…To understand the actual involvement of CB2 in B-ALL, we firstly checked the effects of its selective stimulation on transcription activity. Over the last 10 years, RNA sequencing (RNA-seq) protocols rapidly evolved, and the integration of next generation sequencing into clinics could certainly be a successful clinical tool [ 43 , 44 ]. In our study, we observe a decrease in CD9 , SEC61G , TBX21 , and TMSB4X gene transcription.…”

“…Another important aspect we investigated is the proliferative potential of cancer cells. Cancer cells show a high rate of proliferation, and SEC61G is one of the main genes involved, acting as proto-oncogene and enhancing cancer cell survival [ 44 , 47 ]. It is observed that by knocking it out, EGFR/AKT survival signaling, and tumor growth are inhibited [ 31 ].…”