The pathogenic roles of the p.R130S prestin variant in DFNB61 hearing loss.

DFNB61 is a recessively inherited nonsyndromic hearing loss caused by mutations in SLC26A5, the gene that encodes the voltage-driven motor protein, prestin. Prestin is abundantly expressed in the auditory outer hair cells that mediate cochlear amplification. Two DFNB61-associated SLC26A5 variants, p.W70X and p.R130S, were identified in patients who are compound heterozygous for these nonsense and missense changes (SLC26A5W70X/R130S ). Our recent study showed that mice homozygous for p.R130S (Slc26a5R130S/R130S ) suffer from hearing loss that is ascribed to significantly reduced motor kinetics of prestin. Given that W70X-prestin is nonfunctional, compound heterozygous Slc26a5R130S/- mice were used as a model for human SLC26A5W70X/R130S . By examining the pathophysiological consequences of p.R130S prestin when it is the sole allele for prestin protein production, we determined that this missense change results in progressive outer hair cell loss in addition to its effects on prestin's motor action. Thus, this study defines the pathogenic roles of p.R130S prestin and identifies a limited time window for potential clinical intervention. KEY POINTS: The voltage-driven motor protein, prestin, is encoded by SLC26A5 and expressed abundantly in cochlear outer hair cells (OHCs). The importance of prestin for normal hearing was demonstrated in mice lacking prestin; however, none of the specific SLC26A5 variants identified to date in human patients has been experimentally demonstrated to be pathogenic. In this study we used both cell lines and a mouse model to define the pathogenic role of compound heterozygous p.W70X (c.209G>A) and p.R130S (c.390A>C) SLC26A5 variants identified in patients with moderate to profound hearing loss. As in patients, mice carrying one copy of p.R130S Slc26a5 showed OHC dysfunction and progressive degeneration, which results in congenital progressive hearing loss. This is the first functional study reporting pathogenic SLC26A5 variants and pointing to the presence of a therapeutic time window for potential clinical interventions targeting the affected OHCs before they are lost.

Roles of linker region flanked by transmembrane and peptidoglycan binding region of PomB in energy conversion of the Vibrio flagellar motor.

The flagellar components of Vibrio spp., PomA and PomB, form a complex that transduces sodium ion and contributes to rotate flagella. The transmembrane protein PomB is attached to the basal body T-ring by its periplasmic region and has a plug segment following the transmembrane helix to prevent ion flux. Previously we showed that PomB deleted from E41 to R120 (Δ41-120) was functionally comparable to the full-length PomB. In this study, three deletions after the plug region, PomB (Δ61-120), PomB (Δ61-140), and PomB (Δ71-150), were generated. PomB (Δ61-120) conferred motility, whereas the other two mutants showed almost no motility in soft agar plate; however, we observed some swimming cells with speed comparable for the wild-type cells. When the two PomB mutants were introduced into a wild-type strain, the swimming ability was not affected by the mutant PomBs. Then, we purified the mutant PomAB complexes to confirm the stator formation. When plug mutations were introduced into the PomB mutants, the reduced motility by the deletion was rescued, suggesting that the stator was activated. Our results indicate that the deletions prevent the stator activation and the linker and plug regions, from E41 to S150, are not essential for the motor function of PomB but are important for its regulation.

Unveiling the hidden clues: Döhle body-like inclusions as morphological markers for MYH9-related disorders: A case report.

RATIONALE: This study aimed to address the diagnostic challenges associated with MYH9-related disorders (MYH9-RDs) and highlight the importance of recognizing Döhle body-like inclusions as crucial diagnostic markers for this condition. PATIENT CONCERNS: Patients with MYH9-RDs often present with mild and diverse clinical characteristics, leading to misdiagnosis, delayed diagnosis, and inappropriate treatments, such as hormonal therapy and splenectomy. This section highlights the significance of understanding atypical clinical presentations and their impact on patients' well-being. DIAGNOSES: This section emphasizes the misdiagnosis of MYH9-RDs as immune thrombocytopenia due to overlapping clinical features. This highlights the need for a comprehensive approach, including detailed personal and family history, careful review of peripheral blood smears, and identification of Döhle body-like inclusions to differentiate MYH9-RDs from other conditions. INTERVENTION: This study advocates for a shift in the diagnostic approach, urging physicians to pay closer attention to the morphological features observed in peripheral blood smears, particularly the presence of Döhle body-like inclusions and large platelets. This emphasizes the importance of avoiding unnecessary diagnostic studies through effective utilization of this simple and reliable method. OUTCOMES: By adopting a comprehensive approach that combines gene sequencing with morphological analysis, an accurate diagnosis of MYH9-RDs can be achieved. Early identification of MYH9-RDs allows for appropriate management strategies, genetic counseling, and prevention of complications associated with the condition. LESSONS: This section highlights the lessons learned from this study, emphasizing the need for increased awareness among healthcare professionals about MYH9-RDs and the importance of incorporating peripheral blood smear evaluations into the diagnostic process. This emphasizes the significance of accurate diagnosis to prevent unnecessary treatments and ensure appropriate patient care.

Prestin's fast motor kinetics is essential for mammalian cochlear amplification.

Prestin (SLC26A5)-mediated voltage-driven elongations and contractions of sensory outer hair cells within the organ of Corti are essential for mammalian cochlear amplification. However, whether this electromotile activity directly contributes on a cycle-by-cycle basis is currently controversial. By restoring motor kinetics in a mouse model expressing a slowed prestin missense variant, this study provides experimental evidence acknowledging the importance of fast motor action to mammalian cochlear amplification. Our results also demonstrate that the point mutation in prestin disrupting anion transport in other proteins of the SLC26 family does not alter cochlear function, suggesting that the potential weak anion transport of prestin is not essential in the mammalian cochlea.

High-Resolution Rotation Assay of the Bacterial Flagellar Motor Near Zero Loads Using a Mutant Having a Rod-Like Straight Hook.

The bacterial flagellar motor is embedded within the cell envelop and rotates the long helical filament, which acts as a molecular screw to propel the bacterium. The flagellar motor comprises a rotor and a dozen stator units, converting ion flux through the stator unit into torque. However, the energy coupling mechanism has not been fully understood. Various methods for rotation measurement have been developed to understand the rotation mechanism of the flagellar motor, but the most preferred method in recent studies is a bead assay, which tracks the rotation of a micron to submicron bead attached to the partially sheared flagellar filament at high temporal and spatial resolutions. The bead assay allows us to assess the motor rotation over a wide range of external load, but the elasticity of the axial parts of the flagellum, such as the hook and filament, limits the spatiotemporal resolution. In this chapter, we describe a bead assay optimized for the analysis of the flagellar motor dynamics at near zero load.

Renal injury associated with MYH9 disorder with 5773delG mutation: A case report.

A 35-year-old man with persistent urine abnormalities and renal dysfunction was referred to our hospital. May-Hegglin anomaly was suspected, and a renal biopsy showed focal segmental glomerulosclerosis (FSGS) with IgA deposition. Electron microscopy revealed foot process effacements and intense bleb-like morphological changes in podocytes. Nonmuscle myosin heavy chain IIA (NMMHCIIA) staining of granulocytes revealed a localized, type II pattern, and genomic DNA sequencing of MYH9 exon 40 revealed MYH9 5773delG mutation (c.5773delG [p.(Asp1925Thrfs*23)]). Podocytes were significantly stained by an antibody specific for NMMHC-IIA abnormalities associated with this mutation. Colocalization observation of vimentin and NMMHC-IIA demonstrated a diminished form of NMMHC-IIA in podocytes. Taking these observations into account, it was determined that the present case was likely associated with MYH9 disorder. Treatment was started with olmesartan, followed by methylprednisolone pulse therapy 3 times bi-monthly. Finally, the patient began hemodialysis 18 months later. This is the first known report of renal phenotype expression associated with this MYH9 mutation. FSGS can occur in association with MYH9 mutations at the 3' regions, such as exon 40. Abnormal expression or metabolism of NMMHC-IIA in podocytes might be related to the formation of FSGS lesions due to this MYH9 mutation.

A familial case of MYH9 gene mutation associated with multiple functional and structural platelet abnormalities.

Mutations in the MYH9 gene result in macrothrombocytopenia often associated with hemorrhages. Here, we studied the function and structure of platelets in three family members with a heterozygous mutation R1933X in the MYH9 gene, characteristic of closely related disorders known as the May-Hegglin anomaly and Sebastian syndrome. The examination included complete blood count, blood smear microscopy, platelet flow cytometry (expression of P-selectin and active integrin αIIbß3 before and after activation), the kinetics of platelet-driven contraction (retraction) of blood clots, as well as scanning/transmission electron microscopy of platelets. Despite severe thrombocytopenia ranging (36-86) × 109/l, none of the patients had hemorrhages at the time of examination, although they had a history of heavy menstruation, spontaneous ecchymosis, and postpartum hemorrhage. Flow cytometry showed background platelet activation, revealed by overexpression of P-selectin and active αIIbß3 integrin above normal levels. After TRAP-induced stimulation, the fractions of platelets expressing P-selectin in the proband and her sister were below normal response, indicating partial platelet refractoriness. The initiation of clot contraction was delayed. Electron microscopy revealed giant platelets with multiple filopodia and fusion of α-granules with dilated open canalicular system, containing filamentous and vesicular inclusions. The novel concept implies that the R1933X mutation in the MYH9 gene is associated not only with thrombocytopenia, but also with qualitative structural and functional defects in platelets. Platelet dysfunction includes impaired contractility, which can disrupt the compaction of hemostatic clots, making the clots weak and permeable, therefore predisposing patients with MYH9 gene mutations to the hemorrhagic phenotype.

Avatrombopag improves thrombocytopenia in MYH9-related disorder following eltrombopag treatment failure.

MYH9-related disorder (MYH9-RD) is autosomal dominant thrombocytopenia caused by mutations in the MYH9 gene, which codes for the non-muscle myosin-IIA heavy chain. We present a case of a 24-year-old Chinese man with MYH9-RD who was initially misdiagnosed with immune thrombocytopenia. Whole-exome sequencing and Sanger sequencing revealed a novel missense mutation in the MYH9 gene at the position of c.4550 G > T (p.G1517V) in exon 32. The same phenotype was observed in the proband, his mother, and his brother, in addition to macrothrombocytopenia and Dohle-like bodies in neutrophil granulocytes without non-hematologic manifestations. Following failed treatment with eltrombopag, avatrombopag, which was not mentioned before in the MYH9-RD treatment, was administered to the patient, and thrombocytopenia improved. In this case report, we present a novel pathogenic mutation and show the potential of avatrombopag for temporarily increasing the platelet count in patients with MYH9-RD.

Retraction ATPase Motors from Three Orthologous Type IVa Pilus Systems Support Promiscuous Retraction of the Vibrio cholerae Competence Pilus.

Bacterial surface appendages called type IVa pili (T4aP) promote diverse activities, including DNA uptake, twitching motility, and virulence. These activities rely on the ability of T4aP to dynamically extend and retract from the cell surface. Dynamic extension relies on a motor ATPase commonly called PilB. Most T4aP also rely on specific motor ATPases, commonly called PilT and PilU, to dynamically and forcefully retract. Here, we systematically assess whether motor ATPases from three orthologous T4aP can functionally complement Vibrio cholerae mutants that lack their endogenous motors. We found that the PilT and PilU retraction ATPases from the three T4aP systems tested are promiscuous and promote the retraction of the V. cholerae competence T4aP despite a high degree of sequence divergence. In contrast, the orthologous extension ATPases from the same T4aP systems were not able to mediate the extension of the V. cholerae competence T4aP despite exhibiting a similar degree of sequence divergence. Also, we show that one of the PilT orthologs characterized does not support PilU-dependent retraction and provide some data to indicate that the C terminus of PilT is important for PilU-dependent retraction. Together, our data suggest that retraction ATPases may have maintained a high degree of promiscuity for promoting the retraction of T4aP, while extension ATPases may have evolved to become specific for their cognate systems. IMPORTANCE One way in which bacteria interact with their environments is via hair-like appendages called type IVa pili (T4aP). These appendages dynamically extend and retract from the cell surface via the action of distinct ATPase motors. T4aP are present in diverse bacterial species. Here, we demonstrate that retraction motors from three T4aP are promiscuous and capable of promoting the retraction of a heterologous T4aP system. In contrast, the extension ATPase motors from these same T4aP systems are specific and cannot promote the extension of a heterologous T4aP. Thus, these results suggest that T4aP extension may be more tightly regulated than T4aP retraction.

The surgical management of a patient with chronic renal failure and macrothrombocytopenia related to the MYH9 gene mutation: A case report.

MYH9 disease is a rare genetic disorder in which there is a mutation in the gene for the non-muscle myosin heavy chain IIA. It initially causes macrothrombocytopenia followed by other clinical manifestations. When the patient reaches adulthood, he can develop chronic kidney failure. Thus, the risk of suffering a hemorrhage, difficulty in repairing and, infections increases in individuals with this disease. In addition, the use of drugs in these patients should be carefully evaluated. An adult patient sought dental care with a complaint associated with a tooth with advanced dental caries. He had severe thrombocytopenia (7000 platelets/mm3 ), hearing loss, and chronic kidney failure. The diagnosis of MYH9 disease was confirmed through genotyping. After clinical examination, extraction was planned. Local and systemic procedures were used to prevent hemorrhage, especially postoperatively. Although the patient had an infection at the surgical wound site and no episode of postoperative bleeding, the repair process occurred normally. The purpose of this article is to report the surgical management of a patient with MYH9 disease.

MYH9 binds to dNTPs via deoxyribose moiety and plays an important role in DNA synthesis.

The accepted notion of dNTP transport following cytoplasmic biosynthesis is 'facilitated diffusion'; however, whether this alone is sufficient for moving dNTPs for DNA synthesis remains an open question. The data presented here show that the MYH9 gene encoded heavy chain of non-muscle myosin IIA binds dNTPs potentially serving as a 'reservoir'. Pull-down assays showed that MYH9 present in the cytoplasmic, mitochondrial and nuclear compartments bind to DNA and this interaction is inhibited by dNTPs and 2-deoxyribose-5-phosphate (dRP) suggesting that MYH9-DNA binding is mediated via pentose sugar recognition. Direct dNTP-MYH9 binding was demonstrated by ELISA and a novel PCR-based method, which showed that all dNTPs bind to MYH9 with varying efficiencies. Cellular thermal shift assays showed that MYH9 thermal stability is enhanced by dNTPs. MYH9 siRNA transfection or treatment with myosin II selective inhibitors ML7 or blebbistatin decreased cell proliferation compared to controls. EdU labeling and cell cycle analysis by flow cytometry confirmed MYH9 siRNA and myosin II inhibitors decreased progression to S-phase with accumulation of cells in G0/G1 phase. Taken together, our data suggest a novel role for MYH9 in dNTP binding and DNA synthesis.

FliL ring enhances the function of periplasmic flagella.

SignificanceHow flagella sense complex environments and control bacterial motility remain fascinating questions. Here, we deploy cryo-electron tomography to determine in situ structures of the flagellar motor in wild-type and mutant cells of Borrelia burgdorferi, revealing that three flagellar proteins (FliL, MotA, and MotB) form a unique supramolecular complex in situ. Importantly, FliL not only enhances motor function by forming a ring around the stator complex MotA/MotB in its extended, active conformation but also facilitates assembly of the stator complex around the motor. Our in situ data provide insights into how cooperative remodeling of the FliL-stator supramolecular complex helps regulate the collective ion flux and establishes the optimal function of the flagellar motor to guide bacterial motility in various environments.

In vivo CRISPR-Cas9-mediated DNA chop identifies a cochlear outer hair cell-specific enhancer.

Cochlear outer hair cells (OHCs) are essential for hearing. A short, OHC-specific enhancer is necessary but not yet available for gene therapeutic applications in OHC damage. Such damage is a major cause of deafness. Prestin is a motor protein exclusively expressed in OHCs. We hypothesized that the cis-regulatory DNA fragment deletion of Slc26a5 would affect its expression. We tested this hypothesis by conducting CRISPR/Cas9-mediated large DNA fragment deletion of mouse Slc26a5 intron regions. First, starting from a ~13 kbp fragment, step-by-step, we narrowed down the sequence to a 1.4 kbp segment. By deleting either a 13 kbp or 1.4 kbp fragment, we observed delayed Prestin expression. Second, we showed that 1.4 kbp was an OHC-specific enhancer because enhanced green fluorescent protein (EGFP) was highly and specifically expressed in OHCs in a transgenic mouse where EGFP was driven by the 1.4 kbp segment. More importantly, specific EGFP was also driven by its homologous 398 bp fragment in human Slc26a5. This suggests that the enhancer is likely to be evolutionarily conserved across different species.

Prestin and electromotility may serve multiple roles in cochlear outer hair cells.

Outer hair cells (OHCs) are innervated by both medial olivocochlear (MOC) efferents and type II afferents, which also innervate supporting cells to form a local neural network. It has also been demonstrated that prestin provides the molecular basis for OHC somatic electromotility, amplifying movements within the organ of Corti. Although not anticipated, early-onset OHC loss was found in two prestin transgenic mouse models that either lack prestin protein or lack electromotility. To uncover the molecular pathways that evoke OHC death, we profiled the coding transcriptome of OHCs from wildtype (WT), prestin-knockout (KO), and 499-knockin (KI) mice using single-cell RNA sequencing (scRNA-seq). scRNA-Seq transcriptomics and pathway analyses did not reveal common pathways associated with OHC loss observed in prestin-KO and 499-KI mice. Clustering enrichment analysis showed that increased gene expression in OHCs from prestin-KO mice was associated with lipid metabolic processes and cell death pathways. These mRNA profiles likely contribute to the OHC loss observed in prestin-KO mice and support the notion that prestin is also a structural protein, important for the normal plasma membrane compartmentalization that is essential to establish MOC efferent synapses. In contrast, the mRNA profile of OHCs from 499-KI mice did not provide a rational explanation of the early-onset OHC loss in this mutant. OHCs from 499-KI mice have normal plasma membrane compartmentalization and normal OHC-MOC contacts. However, 499 prestin lacks electromotility and appears to change the local neural network around OHCs, as more synaptic markers were found near neighboring supporting cells when compared to WT and prestin-KO mice. Thus, OHCs in prestin-KOs (no prestin protein, no electromotility) and 499-KIs (prestin protein present, no electromotility) may influence local neuronal networks in different ways. Collectively, our data suggest that prestin and its motile properties are important for OHC survival and the maintenance of local afferent/efferent circuits, as well as for its role in cochlear amplification. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.

The flagellar motor protein FliL forms a scaffold of circumferentially positioned rings required for stator activation.

The flagellar motor stator is an ion channel nanomachine that assembles as a ring of the MotA5MotB2 units at the flagellar base. The role of accessory proteins required for stator assembly and activation remains largely enigmatic. Here, we show that one such assembly factor, the conserved protein FliL, forms an integral part of the Helicobacter pylori flagellar motor in a position that colocalizes with the stator. Cryogenic electron tomography reconstructions of the intact motor in whole wild-type cells and cells lacking FliL revealed that the periplasmic domain of FliL (FliL-C) forms 18 circumferentially positioned rings integrated with the 18 MotAB units. FliL-C formed partial rings in the crystal, and the crystal structure-based full ring model was consistent with the shape of the rings observed in situ. Our data suggest that each FliL ring is coaxially sandwiched between the MotA ring and the dimeric periplasmic MotB moiety of the stator unit and that the central hole of the FliL ring has density that is consistent with the plug/linker region of MotB in its extended, active conformation. Significant structural similarities were found between FliL-C and stomatin/prohibitin/flotillin/HflK/C domains of scaffolding proteins, suggesting that FliL acts as a scaffold. The binding energy released upon association of FliL with the stator units could be used to power the release of the plug helices. The finding that isolated FliL-C forms stable partial rings provides an insight into the putative mechanism by which the FliL rings assemble around the stator units.

Cell biology of primary cell wall synthesis in plants.

Building a complex structure such as the cell wall, with many individual parts that need to be assembled correctly from distinct sources within the cell, is a well-orchestrated process. Additional complexity is required to mediate dynamic responses to environmental and developmental cues. Enzymes, sugars, and other cell wall components are constantly and actively transported to and from the plasma membrane during diffuse growth. Cell wall components are transported in vesicles on cytoskeletal tracks composed of microtubules and actin filaments. Many of these components, and additional proteins, vesicles, and lipids are trafficked to and from the cell plate during cytokinesis. In this review, we first discuss how the cytoskeleton is initially organized to add new cell wall material or to build a new cell wall, focusing on similarities during these processes. Next, we discuss how polysaccharides and enzymes that build the cell wall are trafficked to the correct location by motor proteins and through other interactions with the cytoskeleton. Finally, we discuss some of the special features of newly formed cell walls generated during cytokinesis.

[Gene analysis and clinical features of MYH9-related disease].

Objective: To identify gene variants and investigate clinical features of nonmuscle myosin heavy chain 9-related disease (MYH9-RD). Methods: In this retrospective study, the data of patients with MYH9-RD admitted to Shenzhen Children's Hospital from July 2017 to September 2020 were extracted. The gene variants, clinical features and laboratory tests results were summarized. Results: Among the 6 children, 4 were males and 2 were females, aged 4.0 (0.5-7.6) years. Main clinical manifestations included thrombocytopenia (6 cases), epistaxis (3 cases), petechias (2 cases), traumatic hematoma (1 case), and abnormal liver enzymes (1 case). One patient had no family history, and the other 5 cases were pedigrees. Two pedigrees (2 cases) had long-term microscopic hematuria, one pedigree (2 cases) had history of early cataract, and three pedigrees (5 cases) had chronic mild elevation of liver enzymes. Four MYH9 gene variants were found in 12 patients, including c.2104C>T(p.R702C) in exon 17, c.4270G>A(p.D1424N) in exon 31, c.5521G>A (p.E1841K) in exon 39, and c.5797C>T (p.R1933X) in exon 41. According to the family pedigrees analysis, except for the case of variant in exon 17 which was spontaneous mutation with no family history, the other variants were from their father or mother. The complete blood count results showed a decreased platelet number in these patients, and the counting results of the automated hematology analyzer were significantly lower than that of manual counting method ((33.4±17.2) × 109 vs. (60.4±21.0) × 109/L,t=-5.83, P<0.05). The examination of the peripheral blood smear revealed the presence of thrombocytopenia with giant platelets and granulocyte inclusion bodies. The MYH9 gene variant (R702C) located at the N-terminus head domain of non-muscle myosin heavy chain ⅡA (NMMHC-ⅡA), which has ATPase activity, led to severe reduction of platelet number (<20×109/L) and obscure granulocyte inclusion bodies. However, higher platelet numbers (40×109-80×109/L) and obvious granulocyte inclusion bodies were observed in patients with tail-position mutations at C-terminus. Conclusions: The clinical phenotypes of MYH9-RD were variable. The mutations in certain regions of MYH9 gene were related to platelet count and granulocyte inclusion bodies. MYH9-RD should be considered in individuals with unknown etiology and persistent thrombocytopenia which is non-responsive to conventional treatment, regardless of family history. Complete blood count and blood smear morphology examinations are the first steps to screen and diagnose the disease. The laboratory should pay attention to the morphological review rules and standardized reports.

[Clinical and genetic features of seven children with MYH9-related disease].

Objective: To summarize and analyze of the clinical and genetic characteristics of children with nonmuscle myosin heavy chain 9 (MYH9)-related disease (MYH9-RD). Methods: To screen the patients who were first diagnosed as "chronic/refractory immune thrombocytopenia (ITP) " from April 2016 to May 2019 in Beijing Children's Hospital by genetic and clinical examinations, then the clinical manifestation, laboratory examination and genetics results of 7 children diagnosed with MYH9-RD were collected and summarized retrospectively. Results: Among 7 children diagnosed with MYH9-RD, 3 were males and 4 females. The age of onset was 1.25 (0.41-6.16) years. The course of disease was 2.16 (0.41-8.59) years. The automatic platelet count was (9 (5-30))×109/L. All the cases were found with giant platelets under microscope,and the manual platelet count was (70 (30-100))×109/L. Four cases had skin hemorrhage or epistaxis and 3 cases had no bleeding. All 7 patients had received first-or second-line therapy of ITP, of whom 1 case received splenic embolization, and all the treatments mentioned above were ineffective. Finally, it was confirmed that all 7 patients had heterozygous missense mutations of MYH9 gene by next generation sequencing (NGS), including 2 pedigrees and 5 sporadic cases. Four sporadic mutations occurred in N-terminal globular head domain (HD), and 1 sporadic case with p.D1424N mutations occurred in the C-terminal tail domain (TD). One of the pedigrees also had p.D1424N mutation. The other familial case had a novel variant with one missense variant p.A44D caused by the c.131C>A transition. One of the two p.R702 mutations had kidney damage, and several relatives of the new p.A44D mutations had deafness. Conclusions: In this study, the spontaneous mutations of seven MYH9-RD were common, and all patients were misdiagnosed as ITP, whereas the bleeding was mild and immunotherapy was ineffective. The suspected disease can be identified earlier by manual visual platelet volume and count, which can be confirmed by genetic testing. It is more important to monitor the development of other organs damage instead of thrombocytopenia. For cases with p.R702 mutations the doctor should be aware of kidney damage, and for the cases with novel mutations p.A44D the doctor should be aware of hearing loss.

Cochlear outer hair cell electromotility enhances organ of Corti motion on a cycle-by-cycle basis at high frequencies in vivo.

Mammalian hearing depends on an amplification process involving prestin, a voltage-sensitive motor protein that enables cochlear outer hair cells (OHCs) to change length and generate force. However, it has been questioned whether this prestin-based somatic electromotility can operate fast enough in vivo to amplify cochlear vibrations at the high frequencies that mammals hear. In this study, we measured sound-evoked vibrations from within the living mouse cochlea and found that the top and bottom of the OHCs move in opposite directions at frequencies exceeding 20 kHz, consistent with fast somatic length changes. These motions are physiologically vulnerable, depend on prestin, and dominate the cochlea's vibratory response to high-frequency sound. This dominance was observed despite mechanisms that clearly low-pass filter the in vivo electromotile response. Low-pass filtering therefore does not critically limit the OHC's ability to move the organ of Corti on a cycle-by-cycle basis. Our data argue that electromotility serves as the primary high-frequency amplifying mechanism within the mammalian cochlea.

Dual expression of Atoh1 and Ikzf2 promotes transformation of adult cochlear supporting cells into outer hair cells.

Mammalian cochlear outer hair cells (OHCs) are essential for hearing. Severe hearing impairment follows OHC degeneration. Previous attempts at regenerating new OHCs from cochlear supporting cells (SCs) have been unsuccessful, notably lacking expression of the key OHC motor protein, Prestin. Thus, regeneration of Prestin+ OHCs represents a barrier to restore auditory function in vivo. Here, we reported the successful in vivo conversion of adult mouse cochlear SCs into Prestin+ OHC-like cells through the concurrent induction of two key transcriptional factors known to be necessary for OHC development: Atoh1 and Ikzf2. Single-cell RNA sequencing revealed the upregulation of 729 OHC genes and downregulation of 331 SC genes in OHC-like cells. The resulting differentiation status of these OHC-like cells was much more advanced than previously achieved. This study thus established an efficient approach to induce the regeneration of Prestin+ OHCs, paving the way for in vivo cochlear repair via SC transdifferentiation.