Biomedical subjects

Helder I Nakaya

Publications and source records attributed to Helder I Nakaya.

4 recordsLinked to original sources

PubMed2026

Immune profiling in a living human recipient of a gene-edited pig kidney.

Xenotransplantation of gene-edited pig kidneys offers a promising solution to the shortage of kidneys for organ transplantation. We recently performed a gene-edited pig kidney transplantation into a living human recipient with end-stage kidney disease. Here, using transcriptomics, proteomics, metabolomics and multiplexed imaging, we conducted high-dimensional immune profiling in this individual. Despite profound depletion of circulating T cells, early T cell-mediated rejection occurred within 1 week after transplantation, likely driven by subtherapeutic immunosuppression and the presence of residual CD8+ T cells in lymph nodes. This T cell-mediated rejection event was reversed by intensified immunosuppression. After treatment, adaptive immunity remained suppressed, whereas innate immune activation, characterized by sustained monocyte and macrophage activity along with elevated levels of interleukin-1 beta and granulocyte-macrophage colony-stimulating factor, persisted. Comparative transcriptomic analysis showed that xenograft rejection profiles resembled those typically observed in human allograft rejection, while also revealing unique innate immune signatures. We did not detect antibody-mediated rejection. The levels of circulating pig donor-derived cell-free DNA rose during the initial rejection episode and declined with treatment, supporting the potential of cell-free DNA measurements as a noninvasive biomarker of xenograft rejection. These findings define the distinct immune landscape of kidney xenotransplantation and highlight the need for regimens targeting both innate and adaptive immunity to improve outcomes.

Animals↗

PubMed2005

As antisense RNA gets intronic.

Recent work describing the transcriptional output of the human genome points to the existence of a significant number of non-coding RNA transcripts coming from intronic regions, with a fraction of these being oriented antisense relative to the protein-coding mRNA of the known gene. In this article, we survey the main findings of the large-scale expression analysis projects that led to the identification of antisense intronic messages and which demonstrate their ubiquitous expression in the human genome. We review the current knowledge on long, unspliced, intronic antisense transcripts, a new class of non-coding RNAs, recently described by our group to be correlated with the degree of tumor differentiation in prostate cancer, which we postulate is involved in the fine tuning of gene expression in eukaryotes. Possible mechanisms of antisense intronic transcript biogenesis and function in gene expression regulation are discussed, as is their involvement in human diseases. While there is still no conclusive evidence demonstrating a functional role for these long, intronic antisense messages, the far-reaching implications of their existence for the mechanisms regulating gene expression certainly warrant further experimentation.

Alternative Splicing↗

PubMed2004

Antisense intronic non-coding RNA levels correlate to the degree of tumor differentiation in prostate cancer.

A large fraction of transcripts are expressed antisense to introns of known genes in the human genome. Here we show the construction and use of a cDNA microarray platform enriched in intronic transcripts to assess their biological relevance in pathological conditions. To validate the approach, prostate cancer was used as a model, and 27 patient tumor samples with Gleason scores ranging from 5 to 10 were analyzed. We find that a considerably higher fraction (6.6%, [23/346]) of intronic transcripts are significantly correlated (P< or =0.001) to the degree of prostate tumor differentiation (Gleason score) when compared to transcripts from unannotated genomic regions (1%, [6/539]) or from exons of known genes (2%, [27/1369]). Among the top twelve transcripts most correlated to tumor differentiation, six are antisense intronic messages as shown by orientation-specific RT-PCR or Northern blot analysis with strand-specific riboprobe. Orientation-specific real-time RT-PCR with six tumor samples, confirmed the correlation (P=0.024) between the low/high degrees of tumor differentiation and antisense intronic RASSF1 transcript levels. The need to use intron arrays to reveal the transcriptome profile of antisense intronic RNA in cancer has clearly emerged.

Cell Differentiation↗

PubMed2004

RASL11A, member of a novel small monomeric GTPase gene family, is down-regulated in prostate tumors.

We performed a genome-wide search for novel loci encoding for Ras-related proteins based on the genome mapping coordinates of the cancer-derived EST dataset at GenBank. Partial sequences from two novel human genes were identified and subsequently used for full length transcript cloning. RASL11A and ARL9 belong to two novel subfamilies coding for small GTPases that we found to be highly conserved among eukaryotes. The Arl9/Arl10 subfamily displays a conserved interswitch toggle that places it evolutionarily closer to the Arf family. Rasl11 proteins are more closely related to the Ras branch of GTPases. All orthologues newly identified here exhibit an Asn residue in place of the highly conserved Thr35 of the G domain, suggesting that the universal switch mechanism of small GTPases may be structurally different in this subfamily. We determined by Northern blot that RASL11A is transcribed in several human tissues and that it is down-regulated in prostate tumors as measured by quantitative real-time PCR. These results highlight a previously uncharacterized subfamily of Ras-related genes that may have a tumor suppressor role in prostate cancer.

ADP-Ribosylation Factors↗