Publications by authors named "James R Iben"

Adrenal myelolipomas (AML) are composed of mature adipose and hematopoietic components. They represent approximately 3 percent of adrenal tumors and are commonly found in patients with congenital adrenal hyperplasia (CAH). CAH provides a unique environment to explore AML pathogenesis.

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  • RNA polymerase III (Pol III) is important for making tRNAs and small RNAs, and when it doesn't work right, it can cause health problems in people.
  • Scientists studied a specific problem in a gene that caused mistakes in how RNA is processed and led to changes in some proteins that Pol III needs.
  • They found that people with this mutation had different types of tRNA fragments in their cells, which could help scientists understand the Pol III system better and create new tests for related health issues.
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  • The research focuses on the significance of polyadenylation in the stabilization and translation of messenger RNAs, leading to the development of a new method called SM-PATseq for analyzing poly(A) tail lengths in the entire transcriptome.
  • SM-PATseq uses a specific cDNA synthesis technique involving oligo-dT and random hexamer priming, allowing for precise measurement of tail lengths and detection of non-A bases.
  • The method is designed for use with long-read sequencing technologies, such as the Pacific Biosciences Sequel platform, and aims to improve the quantification of transcript abundance similar to traditional RNA sequencing approaches.
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Introduction: Pituitary adenomas (PAs) are common, usually benign tumors of the anterior pituitary gland which, for the most part, have no known genetic cause. PAs are associated with major clinical effects due to hormonal dysregulation and tumoral impingement on vital brain structures. PAM encodes a multifunctional protein responsible for the essential C-terminal amidation of secreted peptides.

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  • A study linked a specific genetic variant to pituitary gigantism and investigated both sporadic and familial PAs among 299 individuals and 17 families, but no major genetic variations were found.
  • Seven potentially harmful genetic variants were identified that affect protein function, which could lead to new treatments that target these genetic changes and improve outcomes for patients with pituitary disorders.
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  • The study investigates MotB, a protein encoded by an early gene of bacteriophage T4, which may play a role in manipulating the host's genetic expression to aid the virus's takeover.
  • Using advanced methods like RNA-seq and mass spectrometry, the researchers analyzed how overexpressing MotB affects RNA and protein levels during T4 infection in a specific bacterial strain.
  • Findings reveal that MotB has a predicted two-domain structure and influences host gene expression, particularly downregulating several host tRNAs, which may optimize conditions for T4 replication during infection.
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La-related proteins (LARPs) comprise a family of RNA-binding proteins involved in a wide range of posttranscriptional regulatory activities. LARPs share a unique tandem of two RNA-binding domains, La motif (LaM) and RNA recognition motif (RRM), together referred to as a La-module, but vary in member-specific regions. Prior structural studies of La-modules reveal they are pliable platforms for RNA recognition in diverse contexts.

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The small monomeric GTPase RHOA acts as a master regulator of signal transduction cascades by activating effectors of cellular signaling, including the Rho-associated protein kinases ROCK1/2. Previous in vitro cell culture studies suggest that RHOA can regulate many critical aspects of vascular endothelial cell (EC) biology, including focal adhesion, stress fiber formation, and angiogenesis. However, the specific in vivo roles of RHOA during vascular development and homeostasis are still not well understood.

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Introduction: Adrenocortical hyperplasia and adrenal rest tumor (ART) formation are common in congenital adrenal hyperplasia (CAH). Although driven by excessive corticotropin, much is unknown regarding the morphology and transformation of these tissues. Our study objective was to characterize CAH-affected adrenals and ART and compare with control adrenal and gonadal tissues.

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Nucleoid Associated Proteins (NAPs) organize the bacterial chromosome within the nucleoid. The interaction of the NAP H-NS with DNA also represses specific host and xenogeneic genes. Previously, we showed that the bacteriophage T4 early protein MotB binds to DNA, co-purifies with H-NS/DNA, and improves phage fitness.

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Polyadenylation of the 3' end of mRNAs is an important mechanism for regulating their stability and translation. We developed a nucleotide-resolution, transcriptome-wide, single-molecule SM-PAT-Seq method to accurately measure the polyA tail lengths of individual transcripts using long-read sequencing. The method generates cDNA using a double stranded splint adaptor targeting the far 3' end of the polyA tail for first strand synthesis along with random hexamers for second strand synthesis.

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  • - The sla1+ gene in Schizosaccharomyces pombe encodes the La protein, crucial for tRNA processing; its deletion (sla1Δ) disrupts this processing and makes cells sensitive to TOR inhibition, affecting growth and nutrient uptake, particularly leucine.
  • - Transcriptome analysis shows that genes activated in sla1Δ cells have a strong overlap with general amino acid control (GAAC) genes from other studies, indicating a link between tRNA homeostasis and cellular signaling.
  • - Research on cells that reverted back to normal growth (SSR) identified a mutation in the Any1 protein, which regulates leucine uptake; this mutation enhances nutrient absorption in NH4+ media and highlights the connection between amino acid metabolism
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  • The T4 bacteriophage protein MotB binds to DNA and interacts with the host protein H-NS, enhancing the phage's fitness without significantly altering the T4 transcriptome when knocked down.
  • MotB is evolutionarily conserved, featuring a predicted structure that consists of a KOW motif and an OB-fold DNA-binding domain, suggesting its capability to bind DNA.
  • RNA-seq analyses reveal that overexpression of MotB up-regulates 75 host genes, mainly linked to the H-NS regulon, potentially altering host DNA interactions to create conditions favorable for T4 infection.
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La-related protein 4 (LARP4) directly binds both poly(A) and poly(A)-binding protein (PABP). LARP4 was shown to promote poly(A) tail (PAT) lengthening and stabilization of individual mRNAs presumably by protection from deadenylation (Mattijssen et al., 2017).

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Niemann-Pick disease, type C1 (NPC1) is a lysosomal disease characterized by progressive cerebellar ataxia. In NPC1, a defect in cholesterol transport leads to endolysosomal storage of cholesterol and decreased cholesterol bioavailability. Purkinje neurons are sensitive to the loss of NPC1 function.

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Understanding the physiology and pathology of an organ composed of a variety of cell populations depends critically on genome-wide information on each cell type. Here, we report single-cell transcriptome profiling of over 6,800 freshly dispersed anterior pituitary cells from postpubertal male and female rats. Six pituitary-specific cell types were identified based on known marker genes and characterized: folliculostellate cells and hormone-producing corticotrophs, gonadotrophs, thyrotrophs, somatotrophs, and lactotrophs.

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Bones at different anatomical locations vary dramatically in size. For example, human femurs are 20-fold longer than the phalanges in the fingers and toes. The mechanisms responsible for these size differences are poorly understood.

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  • - Bacteriophage T4 utilizes the host's RNA polymerase to transcribe different classes of promoters during infection, with varying dependencies on viral proteins and host factors.
  • - Deleting DksA or ppGpp, two transcription regulators, leads to an increase in T4 plaque size; however, ppGpp deletion does not notably change burst size or transcript levels, while DksA deletion increases burst size and early gene expression.
  • - The study suggests that DksA negatively regulates early gene transcription, which impacts T4's overall productivity during infection, indicating that its regulation of transcription may involve indirect mechanisms or other factors.
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Niemann-Pick disease, type C1 (NPC1) is a neurodegenerative disorder with limited treatment options. NPC1 is associated with neuroinflammation; however, attempts to therapeutically target neuroinflammation in NPC1 have had mixed success. We show here that NPC1 neuroinflammation is characterized by an atypical microglia activation phenotype.

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Background: Niemann-Pick disease, type C (NPC) is a rare lysosomal storage disorder characterized by progressive neurodegeneration, splenomegaly, hepatomegaly, and early death. NPC is caused by mutations in either the NPC1 or NPC2 gene. Impaired NPC function leads to defective intracellular transport of unesterified cholesterol and its accumulation in late endosomes and lysosomes.

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Glucocorticoids have strong effects on diverse human activities through the glucocorticoid receptor (GR). Sirtuin 1 (SIRT1) is a NAD-dependent histone deacetylase and promotes longevity by influencing intermediary metabolism and other regulatory activities including mitochondrial function. In this study, we examined the effects of SIRT1 on GR-mediated transcriptional activity.

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Messenger RNA function is controlled by the 3' poly(A) tail (PAT) and poly(A)-binding protein (PABP). La-related protein-4 (LARP4) binds poly(A) and PABP. mRNA contains a translation-dependent, coding region determinant (CRD) of instability that limits its expression.

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Human La antigen (Sjögren's syndrome antigen B [SSB]) is an abundant multifunctional RNA-binding protein. In the nucleoplasm, La binds to and protects from 3' exonucleases, the ends of precursor tRNAs, and other transcripts synthesized by RNA polymerase III and facilitates their maturation, while a nucleolar isoform has been implicated in rRNA biogenesis by multiple independent lines of evidence. We showed previously that conditional La knockout (La cKO) from mouse cortex neurons results in defective tRNA processing, although the pathway(s) involved in neuronal loss thereafter was unknown.

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tRNA-isopentenyl transferases (IPTases) are highly conserved enzymes that form isopentenyl-N(6)-A37 (i6A37) on subsets of tRNAs, enhancing their translation activity. Nuclear-encoded IPTases modify select cytosolic (cy-) and mitochondrial (mt-) tRNAs. Mutation in human IPTase, TRIT1, causes disease phenotypes characteristic of mitochondrial translation deficiency due to mt-tRNA dysfunction.

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  • During embryonic development, transcription factors and epigenetic modifications help establish and maintain cell identities, but how they interact is not fully understood.
  • The study discovered that the DNA methyltransferase enzyme dnmt3bb.1 is crucial for keeping hematopoietic stem and progenitor cell (HSPC) identity in zebrafish, functioning in a specific signaling pathway.
  • Loss of dnmt3bb.1 activity leads to decreased cmyb expression and HSPCs, while increasing dnmt3bb.1 in non-hematopoietic cells can stimulate hematopoietic development by enhancing cmyb locus methylation.
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