Project description:To identify mRNA substrates for the human RNase MRP complex, we examined the effects of siRNA-mediated depletion of RNase MRP (and RNase P) on the transcriptome of HEp-2 cells. The expression of two RNase MRP protein components, hPop1 and Rpp40, was knocked-down and after 48 hours mRNA was isolated from these cells as well as from cells transfected with an siRNA targeting the GFP mRNA (siEGFP), which was used as a control. The expression levels of mRNAs were analyzed on a genome-wide scale using 21K microarrays.
Project description:The pathogenicity of the malaria parasites results from their ability to invade and remodel red blood cells (RBCs), expressing antigenic variant proteins for immune evasion and survival, and then to egress from the host cell. These sequential processes require concerted actions of a large number of proteins during the intraerythrocytic developmental cycle (IDC)(Boddey and Cowman, 2013; Cowman et al., 2017; Tan and Blackman, 2021), but the molecular basis of the required regulation is only partially understood. Here, we have characterized an essential Apicomplexan AP2 (ApiAP2) transcription factor (we refer to it as PfAP2-MRP; Master Regulator of Pathogenesis) that shows two peaks of expression during the IDC at 16- and 40-hour post-invasion (h.p.i.). When expression of PfAP2-MRP at 40 h.p.i. was disrupted using an inducible gene knockout approach, ∆PfAP2-MRP parasites unable to form mature merozoites and egress from the host RBCs owing to strong down-regulation of several known egress- and invasion-associated genes, in addition to several novel hypothetical genes thought to be involved in these key life cycle processes. Disruption of PfAP2-MRP expression at 16 h.p.i. results in transcriptional activation of the majority of silenced var genes observed at both bulk and single-cell level. This is also reflected by a significantly higher level of immuno-recognition of the exported proteins on the ∆PfAP2-MRP parasite-infected RBCs by pooled sera from malaria-exposed individuals from an endemic region. In addition, overexpression of many early gametocyte marker genes was also observed in ∆PfAP2-MRP parasites at both 40 h.p.i., and at 16 h.p.i. PfAP2-MRP directly regulates these genes by binding to their promoter region or indirectly through 14 other downstream AP2 transcription factors. Taken together, we conclude that PfAP2-MRP is an upstream transcriptional regulator that participates in mutually exclusive expression patterns shown by the var family of genes and is a critical determinant of parasite's growth during the IDC.
Project description:Mutations in the human RMRP gene cause Cartilage Hair Hypoplasia (CHH), an autosomal recessive disorder characterized by skeletal abnormalities and impaired T-cell activation. RMRP encodes a non-coding RNA, which forms the core of the RNase MRP ribonucleoprotein complex. In budding yeast, RMRP cleaves a specific site in the pre-ribosomal RNA (pre-rRNA) during ribosome synthesis. CRISPR-mediated disruption of RMRP in human cells lines caused growth arrest, with pre-rRNA accumulation. Here, we analyzed disease-relevant primary cells, showing that mutations in RMRP impair mouse T cell activation and delay pre-rRNA processing. Analysis of pre-rRNA processing in patient-derived human fibroblasts with CHH-linked mutations showed a similar pattern of processing delay. Human cells engineered with the most common CHH mutation (70AG in RMRP) show specifically impaired pre-rRNA processing, resulting in reduced mature rRNA and a reduced ratio of cytosolic to mitochondrial ribosomes. Moreover, the 70AG mutation caused a reduction in intact RNase MRP complexes. Together, these results indicate that CHH is a ribosomopathy, and the first human disorder of rRNA processing to be described.
Project description:Mutations in the human RMRP gene cause Cartilage Hair Hypoplasia (CHH), an autosomal recessive disorder characterized by skeletal abnormalities and impaired T-cell activation. RMRP encodes a non-coding RNA, which forms the core of the RNase MRP ribonucleoprotein complex. In budding yeast, RMRP cleaves a specific site in the pre-ribosomal RNA (pre-rRNA) during ribosome synthesis. CRISPR-mediated disruption of RMRP in human cells lines caused growth arrest, with pre-rRNA accumulation. Here, we analyzed disease-relevant primary cells, showing that mutations in RMRP impair mouse T cell activation and delay pre-rRNA processing. Analysis of pre-rRNA processing in patient-derived human fibroblasts with CHH-linked mutations showed a similar pattern of processing delay. Human cells engineered with the most common CHH mutation (70AG in RMRP) show specifically impaired pre-rRNA processing, resulting in reduced mature rRNA and a reduced ratio of cytosolic to mitochondrial ribosomes. Moreover, the 70AG mutation caused a reduction in intact RNase MRP complexes. Together, these results indicate that CHH is a ribosomopathy, and the first human disorder of rRNA processing to be described.
Project description:Mutations in the human RMRP gene cause Cartilage Hair Hypoplasia (CHH), an autosomal recessive disorder characterized by skeletal abnormalities and impaired T-cell activation. RMRP encodes a non-coding RNA, which forms the core of the RNase MRP ribonucleoprotein complex. In budding yeast, RMRP cleaves a specific site in the pre-ribosomal RNA (pre-rRNA) during ribosome synthesis. CRISPR-mediated disruption of RMRP in human cells lines caused growth arrest, with pre-rRNA accumulation. Here, we analyzed disease-relevant primary cells, showing that mutations in RMRP impair mouse T cell activation and delay pre-rRNA processing. Analysis of pre-rRNA processing in patient-derived human fibroblasts with CHH-linked mutations showed a similar pattern of processing delay. Human cells engineered with the most common CHH mutation (70AG in RMRP) show specifically impaired pre-rRNA processing, resulting in reduced mature rRNA and a reduced ratio of cytosolic to mitochondrial ribosomes. Moreover, the 70AG mutation caused a reduction in intact RNase MRP complexes. Together, these results indicate that CHH is a ribosomopathy, and the first human disorder of rRNA processing to be described.
Project description:Mutations in the human RMRP gene cause Cartilage Hair Hypoplasia (CHH), an autosomal recessive disorder characterized by skeletal abnormalities and impaired T-cell activation. RMRP encodes a non-coding RNA, which forms the core of the RNase MRP ribonucleoprotein complex. In budding yeast, RMRP cleaves a specific site in the pre-ribosomal RNA (pre-rRNA) during ribosome synthesis. CRISPR-mediated disruption of RMRP in human cells lines caused growth arrest, with pre-rRNA accumulation. Here, we analyzed disease-relevant primary cells, showing that mutations in RMRP impair mouse T cell activation and delay pre-rRNA processing. Analysis of pre-rRNA processing in patient-derived human fibroblasts with CHH-linked mutations showed a similar pattern of processing delay. Human cells engineered with the most common CHH mutation (70AG in RMRP) show specifically impaired pre-rRNA processing, resulting in reduced mature rRNA and a reduced ratio of cytosolic to mitochondrial ribosomes. Moreover, the 70AG mutation caused a reduction in intact RNase MRP complexes. Together, these results indicate that CHH is a ribosomopathy, and the first human disorder of rRNA processing to be described.