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Robert J Morell

Publications and source records attributed to Robert J Morell.

12 recordsLinked to original sources
PubMed2026

CASZ1 regulates the maturation of outer hair cells and is required for hearing in mice.

The transcription factor ATOH1 is a master regulator of mechanosensory hair-cell (HC) development in the ear. Here, we report that its target gene Casz1 regulates the maturation of outer HCs (OHCs). Genetic deletion of Casz1 during (but not after) cochlear development in the mouse caused: hearing loss; disorganization of mechanosensory stereocilia bundles in OHCs; reduced F-actin density in OHC cuticular plates; progressive OHC loss; and mild morphological alterations in inner HCs. This deletion also altered gene expression, delaying downregulation of genes expressed in immature OHCs, including the actin regulator-encoding gene Coro2a, and accelerating upregulation of genes expressed in mature OHCs. Deleting Coro2a in Casz1 mutant mice restored F-actin density in cuticular plates but increased stereocilia bundle disorganization and hearing thresholds, revealing that CORO2A provides an overall beneficial effect. Our data indicate that CASZ1 regulates transcriptional and morphological maturation of OHCs, and that CASZ1 in maturing HCs is necessary for hearing.

CASZ1↗
PubMed2025

GZMK+CD8+ T cells target a specific acinar cell type in Sjögren's disease.

OBJECTIVES: Sjögren's disease (SjD) is a systemic autoimmune disorder characterized by dysfunction of exocrine glands, particularly the salivary and lacrimal glands, with no clear etiology or effective therapy. This study explores the complex interplay of varied cell types in the salivary glands and their role in the pathology of Sjögren's disease. METHODS: Utilizing single-cell and spatial transcriptomics alongside spatial immunophenotyping to analyze human minor salivary glands, we developed a comprehensive understanding of the cellular landscape of non-SjD salivary glands and how that landscape changes in SjD patients. In vitro cellular assays and novel patient-derived primary epithelial cells were co-cultured with autologous T cells to confirm effector states and the delivery and effect of disease-associated granzymes. RESULTS: We identified previously unrecognized heterogeneity among acinar cells, including a PRR4⁺CST3⁺WFDC2⁻ seromucous acinar population that is selectively lost in Sjögren's disease. Expression and organizational changes were linked to clinical features: (i) T cells in the glands of SSA⁺, high-focus score patients showed increased transcriptional signatures of activation, antigen presentation, and apoptosis resistance compared with patients with mild or moderate disease, and (ii) patients with low immune infiltration exhibited distinct epithelial organization. Notably, GZMK⁺CD8⁺ T cells, which accumulate with disease severity, displayed a cytotoxic transcriptional program, degranulated upon stimulation ex vivo, and localized spatially with immune-engaged epithelial cells. Functional assays demonstrated that GZMK activates interferon signaling in vitro, and autologous co-cultures of patient-derived T cells and epithelial cells validated these findings. CONCLUSIONS: Using single-cell and spatial transcriptomics and proteomics, this study identifies a selective loss of PRR4⁺CST3⁺WFDC2⁻ seromucous acinar cells and a rise in GZMK⁺CD8⁺ T cells in Sjögren's disease, revealing distinct immune-mediated epithelial remodeling and interferon-driven dysfunction across diverse clinical presentations. These findings uncover a novel sub-cytolytic effector mechanism by which GZMK⁺CD8⁺ T cells impair mitochondrial integrity and activate innate immune signaling, linking epithelial injury to type I interferon responses and offering new therapeutic targets.

Humans↗
PubMed2025

Molecular differences between young and mature stria vascularis from organotypic explants and transcriptomics.

The stria vascularis (SV) is an essential component of the inner ear that regulates the ionic environment required for hearing. SV degeneration disrupts cochlear homeostasis, leading to irreversible hearing loss, yet a comprehensive understanding of the SV, and consequently therapeutic availability for SV degeneration, is lacking. We developed a whole-tissue explant model from neonatal and mature mice to create a platform for advancing SV research. We validated our model by demonstrating that the proliferative behavior of the SV in vitro mimics SV in vivo. We also provided evidence for pharmacological experimentation by investigating the role of Wnt/β-catenin signaling in SV proliferation. Finally, we performed single-cell RNA sequencing from in vivo neonatal and mature mouse SV and surrounding tissue and revealed key genes and pathways that may play a role in SV proliferation and maintenance. Together, our results contribute new insights into investigating biological solutions for SV-associated hearing loss.

Biochemistry↗
PubMed2006

Signatures from tissue-specific MPSS libraries identify transcripts preferentially expressed in the mouse inner ear.

Specialization in cell function and morphology is influenced by the differential expression of mRNAs, many of which are expressed at low abundance and restricted to certain cell types. Detecting such transcripts in cDNA libraries may require sequencing millions of clones. Massively parallel signature sequencing (MPSS) is well suited to identifying transcripts that are expressed in discrete cell types and in low abundance. We have made MPSS libraries from microdissections of three inner ear tissues. By comparing these MPSS libraries to those of 87 other tissues included in the Mouse Reference Transcriptome online resource, we have identified genes that are highly enriched in, or specific to, the inner ear. We show by RT-PCR and in situ hybridization that signatures unique to the inner ear libraries identify transcripts with highly specific cell-type localizations. These transcripts serve to illustrate the utility of a resource that is available to the research community. Utilization of these resources will increase the number of known transcription units and expand our knowledge of the tissue-specific regulation of the transcriptome.

Animals↗
PubMed2005

Mutations in TRIOBP, which encodes a putative cytoskeletal-organizing protein, are associated with nonsyndromic recessive deafness.

In seven families, six different mutant alleles of TRIOBP on chromosome 22q13 cosegregate with autosomal recessive nonsyndromic deafness. These alleles include four nonsense (Q297X, R788X, R1068X, and R1117X) and two frameshift (D1069fsX1082 and R1078fsX1083) mutations, all located in exon 6 of TRIOBP. There are several alternative splice isoforms of this gene, the longest of which, TRIOBP-6, comprises 23 exons. The linkage interval for the deafness segregating in these families includes DFNB28. Genetic heterogeneity at this locus is suggested by three additional families that show significant evidence of linkage of deafness to markers on chromosome 22q13 but that apparently have no mutations in the TRIOBP gene.

Alternative Splicing↗
PubMed2005

Spatiotemporal pattern and isoforms of cadherin 23 in wild type and waltzer mice during inner ear hair cell development.

Mutant alleles of the gene encoding cadherin 23 are associated with Usher syndrome type 1 (USH1D), isolated deafness (DFNB12) in humans, and deafness and circling behavior in waltzer (v) mice. Stereocilia of waltzer mice are disorganized and the kinocilia misplaced, indicating the importance of cadherin 23 for hair bundle development. Cadherin 23 was localized to developing stereocilia and proposed as a component of the tip link. We show that, during development of the inner ear, cadherin 23 is initially detected in centrosomes at E14.5, then along the length of emerging stereocilia, and later becomes concentrated at and subsequently disappears from the tops of stereocilia. In mature vestibular hair bundles, cadherin 23 is present along the kinocilium and in the region of stereocilia-kinocilium bonds, a pattern conserved in mammals, chicks, and frogs. Cadherin 23 is also present in Reissner's membrane (RM) throughout development. In homozygous v(6J) mice, a reported null allele, cadherin 23 was absent from stereocilia, but present in kinocilia, RM, and centrosomes. We reconciled these results by identifying two novel isoforms of Cdh23 unaffected in sequence and expression by the v(6J) allele. Our results suggest that Cdh23 participation in stereocilia links may be restricted to developing hair bundles.

Alleles↗
PubMed2005

Modification of human hearing loss by plasma-membrane calcium pump PMCA2.

Five adult siblings presented with autosomal recessive sensorineural hearing loss: two had high-frequency loss, whereas the other three had severe-to-profound loss affecting all frequencies. Genetic evaluation revealed that a homozygous mutation in CDH23 (which encodes cadherin 23) caused the hearing loss in all five siblings and that a heterozygous, hypofunctional variant (V586M) in plasma-membrane calcium pump PMCA2, which is encoded by ATP2B2, was associated with increased loss in the three severely affected siblings. V586M was detected in two unrelated persons with increased sensorineural hearing loss, in the other caused by a mutation in MYO6 (which encodes myosin VI) in one and by noise exposure, suggesting that this variant may modify the severity of sensorineural hearing loss caused by a variety of factors.

Adult↗
PubMed2004

Characterization of a new full length TMPRSS3 isoform and identification of mutant alleles responsible for nonsyndromic recessive deafness in Newfoundland and Pakistan.

BACKGROUND: Mutant alleles of TMPRSS3 are associated with nonsyndromic recessive deafness (DFNB8/B10). TMPRSS3 encodes a predicted secreted serine protease, although the deduced amino acid sequence has no signal peptide. In this study, we searched for mutant alleles of TMPRSS3 in families from Pakistan and Newfoundland with recessive deafness co-segregating with DFNB8/B10 linked haplotypes and also more thoroughly characterized the genomic structure of TMPRSS3. METHODS: We enrolled families segregating recessive hearing loss from Pakistan and Newfoundland. Microsatellite markers flanking the TMPRSS3 locus were used for linkage analysis. DNA samples from participating individuals were sequenced for TMPRSS3. The structure of TMPRSS3 was characterized bioinformatically and experimentally by sequencing novel cDNA clones of TMPRSS3. RESULTS: We identified mutations in TMPRSS3 in four Pakistani families with recessive, nonsyndromic congenital deafness. We also identified two recessive mutations, one of which is novel, of TMPRSS3 segregating in a six-generation extended family from Newfoundland. The spectrum of TMPRSS3 mutations is reviewed in the context of a genotype-phenotype correlation. Our study also revealed a longer isoform of TMPRSS3 with a hitherto unidentified exon encoding a signal peptide, which is expressed in several tissues. CONCLUSION: Mutations of TMPRSS3 contribute to hearing loss in many communities worldwide and account for 1.8% (8 of 449) of Pakistani families segregating congenital deafness as an autosomal recessive trait. The newly identified TMPRSS3 isoform e will be helpful in the functional characterization of the full length protein.

Alleles↗
PubMed2003

Mutations of MYO6 are associated with recessive deafness, DFNB37.

Cosegregation of profound, congenital deafness with markers on chromosome 6q13 in three Pakistani families defines a new recessive deafness locus, DFNB37. Haplotype analyses reveal a 6-cM linkage region, flanked by markers D6S1282 and D6S1031, that includes the gene encoding unconventional myosin VI. In families with recessively inherited deafness, DFNB37, our sequence analyses of MYO6 reveal a frameshift mutation (36-37insT), a nonsense mutation (R1166X), and a missense mutation (E216V). These mutations, along with a previously published missense allele linked to autosomal dominant progressive hearing loss (DFNA22), provide an allelic spectrum that probes the relationship between myosin VI dysfunction and the resulting phenotype.

Amino Acid Sequence↗
PubMed2002

Mutation of a transcription factor, TFCP2L3, causes progressive autosomal dominant hearing loss, DFNA28.

We ascertained a large American family with an autosomal dominant form of progressive non-syndromic sensorineural hearing loss. After excluding linkage to known deafness loci, we performed a genome-wide scan and found linkage to marker GAAT1A4 on chromosome 8q22 (LOD=5.12 at theta=0), and this locus was designated DFNA28. Sequencing of six candidate genes in the 1.4 cM linked region identified a frameshift mutation (1609-1610insC) resulting in a premature translation stop codon in exon 14 of the gene TFCP2L3 (transcription factor cellular promoter 2-like 3). TFCP2L3 is a member of a family of transcription factor genes whose archetype is TFCP2, a mammalian homolog of the Drosophila gene grainyhead. Northern blot analyses and in situ hybridization studies show that mouse Tfcp2l3 is expressed in many epithelial tissues, including cells lining the cochlear duct, at embryonic day 18.5 and postnatal day 5.

Adolescent↗
PubMed2002

Mutations in a novel gene, TMIE, are associated with hearing loss linked to the DFNB6 locus.

We have identified five different homozygous recessive mutations in a novel gene, TMIE (transmembrane inner ear expressed gene), in affected members of consanguineous families segregating severe-to-profound prelingual deafness, consistent with linkage to DFNB6. The mutations include an insertion, a deletion, and three missense mutations, and they indicate that loss of function of TMIE causes hearing loss in humans. TMIE encodes a protein with 156 amino acids and exhibits no significant nucleotide or deduced amino acid sequence similarity to any other gene.

Amino Acid Sequence↗